CN101359944A - Method, system, base station and user equipment determining cyclic delay and diversity delay - Google Patents
Method, system, base station and user equipment determining cyclic delay and diversity delay Download PDFInfo
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Abstract
The invention discloses a plurality of methods to determine a delay value of cyclic delay diversity as well as a system, a base station and a user equipment. One of the methods includes: A1. The user equipment gets the CDD delay values in a pre-coding code book which can achieve the best channel quality on each sub-band according to the channel estimation result and feeds back the values to the base station; A2. The base station selects the global CDD delay values in the pre-coding code book according to the received CDD delay values in the best local pre-coding code book from each user equipment; A3. The base station updates the CDD delay values in the pre-coding code book according to the selected global CDD delay values in the pre-coding code book. The invention provides methods, the system, the base station and the user equipment to determine the CDD delay values (groups) in a pre-coding system combining with CDD, and realizes the adaptive update of the CDD delay values (groups) so as to provide guarantee for the system performance to the maximum.
Description
Technical Field
The present invention relates to a multiple-input multiple-output-orthogonal frequency division multiple access (MIMO-OFDMA) system, and in particular, to a method, a system, a base station, and a user equipment for determining a Cyclic Delay Diversity (CDD) delay value (group) in a precoding codebook when a CDD precoding technique is applied in a MIMO-OFDMA system to perform multi-user scheduling.
Background
With the wide application and continuous development of MIMO-OFDMA systems, people introduce a precoding technique based on cyclic delay diversity to further improve the performance of the systems.
The precoding technique is an effective method capable of improving system performance, and the method can reduce the complexity of a receiving end and improve the system performance by preprocessing signals at the transmitting end. Especially, when the system operates in a downlink spatial division multiplexing multiple access (SDMA) mode, joint detection between different terminals is not possible, thereby limiting the transmission capability of the system (joint detection is not required in a transmit diversity mode (TD) and a single-user Spatial Division Multiplexing (SDM) mode).
In the precoding technology, different terminals feed back channel information to a base station in real time, and the base station obtains optimal precoding processing through calculation. The precoding process may be linear or non-linear, where the non-linear precoding complexity is high. In a linear precoding system, different data streams are linearly weighted at the transmitting end and expressed as Y by a mathematical expressionNr×1＝HNr×NtPNt×NsXNs×1+NNr×1Where Nr is the number of receiving antennas, Nt is the number of transmitting antennas, Ns is the number of data streams transmitted simultaneously, Y is the signal of the receiving end, H is the channel matrix, P is the precoding matrix, and X is the data stream with different Ns, which may be the data streamThe data stream of the same user may also be the data stream of different users, and N is noise. In order to realize the optimal linear precoding, the user needs to feed back the channel matrix H in real time. In Orthogonal Frequency Division Multiplexing (OFDM) and orthogonal frequency division multiplexing multiple access (OFDMA) systems, the channel matrix H is fed back on each subcarrier (subcarrier)/resource block (resource block), which requires a large uplink feedback channel bandwidth, which is impractical in many practical systems, even if there are many algorithms to reduce the uplink feedback overhead. A codebook (codebook) -based precoding system is proposed in this case.
As shown in fig. 1, in a MIMO-ofdm (a) system based on codebook-based precoding, there is a pre-designed codebook at the base station, where the codebook includes a plurality of precoding matrices, each matrix includes a plurality of precoding vectors, and the matrices and vectors are pre-designed according to different channels (e.g. statistics of channels, etc.), different optimization criteria (e.g. maximizing capacity, minimizing error rate, etc.). The data streams (streams) in fig. 1 may be different data streams of the same user, or data streams of different users, the pre-coding module performs pre-coding operation on the scheduled data streams, the inverse fourier transform module performs inverse fourier transform (IFFT) on the data, and the cyclic prefix insertion module inserts Cyclic Prefixes (CP). In practical application, the terminal does not need to feed back a real-time Channel coefficient to the base station, but feeds back an index of a matrix or a vector which is most matched with a real-time Channel in a codebook to the base station, and feeds back a Channel Quality Indicator (CQI) corresponding to the matrix or the vector to the base station; after receiving the feedback information of the terminal, the base station performs multi-user scheduling according to the channel quality identifiers of different users and corresponding scheduling algorithms, and then directly uses the matrix or vector fed back by the scheduled user as a precoding coefficient of the transmitting end without recalculation.
Since quantization of channel coefficients requires several bits to achieve high quantization accuracy (e.g., 10 bits), and in a MIMO system, channels between different transmit antennas and different receive antennas all need quantization (feedback overhead per carrier is 10 × Nr × Nt), whereas in a codebook-based precoding system, only a matrix index and a vector index need to be fed back (e.g., indexes of 4 matrices only need 2 bits, and indexes of two vectors per matrix only need 1 bit), the codebook-based precoding technique can greatly reduce feedback overhead. From the performance point of view, in the codebook-based precoding, the precoding coefficients are selected from several pre-calculated coefficients, so that it cannot be guaranteed that the precoding is optimal at every moment, and in general, the performance of the codebook-based precoding technique is slightly worse than that of the optimal non-codebook precoding technique. However, this performance gap can be reduced by increasing the number of precoding coefficients in the codebook, because the more precoding coefficients in the codebook, the higher the probability of the occurrence of the coefficients matching the channel that can be selected by the user, and the better the performance of the codebook-based precoding. Meanwhile, the increase of the number of precoding systems in the codebook will also result in a corresponding increase of feedback overhead, so a suitable codebook size should be selected according to the system requirements such as performance and feedback overhead.
The basic operating principle of the precoding system is described above. There are many existing methods for the design of precoding system codebooks and are not described in detail herein.
The precoding technology combined with CDD introduces CDD on the basis of the original precoding codebook, namely the form of the codebook is changed into
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Wherein P isCDD-based precodingIs a codebook of a precoding system using the CDD technique, diag () is a diagonal matrix, k is a subcarrier index, diIs the corresponding CDD delay value on the ith transmitting antenna, Nc is the number of sub-carriers, PconventionalThe code book is designed by the traditional precoding method. PconventionalThe code book is designed according to different optimization criteria, and after CDD is combined, the fluctuation characteristic of a channel in a frequency domain can be changed, so that greater multi-user diversity gain and/or frequency domain diversity gain can be obtained. In addition, PconventionalOr a unit array, thus being equivalent to a pure CDD system.
However, the conventional codebook design method does not have a method how to design the delay value (set) of CDD, so how to determine the delay value (set) of CDD in the precoding system combined with CDD to improve the system performance becomes a technical problem to be solved urgently.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a method, a system, a base station and user equipment for determining CDD delay value (group) in a precoding system combined with CDD, so as to implement adaptive update of CDD delay value (group), thereby ensuring system performance to the maximum extent.
In order to solve the technical problems, the invention provides the following scheme:
a method for determining delay value of cyclic delay diversity is used for precoding system of combining CDD including base station and several user equipments, including the steps:
a1, the user equipment respectively obtains the CDD delay value in the precoding code book which can obtain the optimal channel quality on each sub-band according to the channel estimation result, and feeds back the CDD delay value to the base station;
a2, the base station selects the CDD delay value in the global precoding codebook according to the CDD delay value in the received local optimal precoding codebook from each user equipment;
a3, the base station updates the CDD delay value in the precoding code book according to the selected CDD delay value in the global precoding code book.
The method of the present invention, wherein the step a1 further comprises the following steps:
the base station sends a starting signal to the user equipment, and starts the updating process of the CDD delay value in the precoding codebook, or the user equipment periodically and automatically starts the updating process of the CDD delay value in the precoding codebook.
The method of the present invention, wherein the step a1 further comprises the steps of:
the user equipment carries out channel estimation by using the pilot frequency information sent by the base station;
the user equipment respectively acquires the CDD delay value in the precoding codebook, which can obtain the maximum capacity, the maximum data rate or the minimum bit error rate, on each sub-band according to the channel estimation result;
and the user equipment sends the CDD delay value in the acquired local optimal precoding codebook to the base station.
In the method of the present invention, the ue obtains the CDD delay value in the precoding codebook that can obtain the optimal channel quality on each subband, and traverses and tests all possible CDD delay values in the preset CDD delay value range on each subband one by one to obtain the optimal CDD delay value that can enable the ue to obtain the optimal channel quality.
In the method of the present invention, the CDD delay value in the precoding codebook that can obtain the optimal channel quality is obtained by the user equipment on each sub-band, and the optimal CDD delay value corresponding to the optimal channel quality that can be obtained by the user equipment on each sub-band is obtained by calculation.
The method of the present invention, wherein the step a2 further comprises the steps of:
the base station receives CDD delay values in the local optimal precoding code books from each user equipment and performs probability distribution analysis on the CDD delay values;
and the base station selects Nt CDD delay values with the maximum probability as CDD delay values in the global precoding code book, wherein Nt is the number of the transmitting antennas.
The method of the present invention, wherein the step a1 further comprises the steps of:
the user equipment respectively acquires a CDD delay value in a precoding code book capable of obtaining the optimal channel quality on each sub-band according to the channel estimation result, and feeds the optimal CDD delay value and the corresponding channel quality back to the base station;
the step A2 further comprises the steps of:
a base station receives CDD delay values and corresponding channel qualities in local optimal precoding code books from all user equipment, and performs probability distribution analysis on the channel qualities corresponding to the CDD delay values in the received precoding code books;
and the base station selects Nt CDD delay values with the maximum channel quality probability as the CDD delay values in the global precoding code book.
A system for determining a delay value of cyclic delay diversity comprises a base station and a plurality of user equipment; the base station includes: a precoding codebook module for storing a precoding codebook in combination with the CDD; the user equipment includes: a baseband demodulation module having a channel estimation sub-module; wherein:
the user equipment further comprises:
a CDD delay value obtaining module in the local optimal precoding codebook, configured to obtain, on each subband, a CDD delay value in the local optimal precoding codebook that can obtain the optimal channel quality according to a channel estimation result output by the channel estimation submodule, and send the CDD delay value in the local optimal precoding codebook to the base station;
the base station further comprises:
the feedback information receiving module is used for receiving CDD delay values in the local optimal precoding code books sent by each user equipment;
and the probability analysis module is used for carrying out probability distribution analysis on CDD delay values in the local optimal precoding codebook of each user equipment, selecting Nt CDD delay values with the maximum probability as global CDD delay values in the precoding codebook, and sending the global CDD delay values to the CDD-combined precoding codebook module so as to update the CDD delay values in the precoding codebook.
The system of the present invention, wherein,
the CDD delay value obtaining module in the local optimal precoding codebook in the user equipment is further configured to obtain, on each sub-band, a CDD delay value in the local optimal precoding codebook that can obtain the optimal channel quality according to a channel estimation result output by the channel estimation submodule, and send the CDD delay value in the local optimal precoding codebook and the channel quality corresponding to the CDD delay value to the base station;
a feedback information receiving module in the base station, further configured to receive CDD delay values in the local optimal precoding codebook sent by each user equipment and channel qualities corresponding to the CDD delay values;
the probability analysis module in the base station is further configured to perform probability distribution analysis on channel quality corresponding to the CDD delay value in the local optimal precoding codebook of each user equipment, select Nt CDD delay values with the largest channel quality probability as CDD delay values in the global precoding codebook, and send the CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
The system of the present invention, wherein,
the base station further comprises: a starting update signal sending module, configured to send a starting signal for updating the CDD delay value to each user equipment;
the user equipment further comprises: and the starting updating signal receiving module is used for receiving the CDD delay value updating starting signal from the base station and starting the CDD delay value acquiring module in the local optimal precoding codebook.
The system of the present invention, wherein,
the user equipment further comprises: and the timing module is used for periodically generating and sending a CDD delay value starting updating signal to the CDD delay value acquisition module in the local optimal precoding codebook.
A base station comprising a combined CDD precoding codebook module for storing a precoding codebook; further comprising:
the feedback information receiving module is used for receiving CDD delay values in the local optimal precoding code books sent by each user equipment;
and the probability analysis module is used for carrying out probability distribution analysis on CDD delay values in the local optimal precoding codebook of each user equipment, selecting Nt CDD delay values with the maximum probability as global CDD delay values in the precoding codebook, and sending the global CDD delay values to the CDD-combined precoding codebook module so as to update the CDD delay values in the precoding codebook.
The base station of the present invention, wherein,
the feedback information receiving module is further configured to receive CDD delay values in the local optimal precoding codebook sent by each user equipment and channel quality corresponding to the CDD delay values;
the probability analysis module is further configured to perform probability distribution analysis on channel quality corresponding to the CDD delay value in the local optimal precoding codebook of each user equipment, select Nt CDD delay values with the largest channel quality probability as CDD delay values in the global precoding codebook, and send the CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
The base station of the present invention further comprises:
and the starting updating signal sending module is used for sending a starting signal for updating the CDD delay value to each user equipment.
A user equipment comprising a baseband demodulation module having a channel estimation sub-module, further comprising:
and the CDD delay value acquisition module in the local optimal precoding codebook is used for respectively acquiring the CDD delay value in the local optimal precoding codebook capable of acquiring the optimal channel quality on each sub-band according to the channel estimation result output by the channel estimation submodule and transmitting the CDD delay value in the local optimal precoding codebook to the base station.
The user equipment of the present invention, wherein the module for obtaining CDD delay values in the local optimal precoding codebook is further configured to obtain CDD delay values in the local optimal precoding codebook, which can obtain the optimal channel quality, on each sub-band according to the channel estimation result output by the channel estimation sub-module, and send the CDD delay values in the local optimal precoding codebook and the channel quality corresponding to the CDD delay values to the base station.
The user equipment of the present invention further comprises:
and the starting updating signal receiving module is used for receiving the CDD delay value updating starting signal from the base station and starting the CDD delay value acquiring module in the local optimal precoding codebook.
The user equipment of the present invention further comprises:
and the timing module is used for periodically generating and sending a CDD delay value starting updating signal to the CDD delay value acquisition module in the local optimal precoding codebook.
A method for determining delay value of cyclic delay diversity is used for precoding system of combining CDD including base station and several user equipments, including the steps:
b1, the user equipment judges the channel characteristics according to the channel estimation result and feeds back the obtained channel characteristic information to the base station;
b2, the base station selects the CDD delay value in the global precoding code book according to the received channel characteristic information from each user equipment;
and B3, the base station updates the CDD delay value in the precoding code book according to the selected CDD delay value in the global precoding code book.
The method of the present invention, wherein the step B1 further comprises the following steps:
the base station sends a starting signal to the user equipment, and starts the updating process of the CDD delay value in the precoding codebook, or the user equipment periodically and automatically starts the updating process of the CDD delay value in the precoding codebook.
The method of the present invention, wherein the step B2 further comprises the steps of:
the base station receives the channel characteristic information from each user equipment and carries out probability distribution analysis on the channel characteristic information;
and the base station selects Nt CDD delay values matched with the channel characteristics with the maximum probability as the CDD delay values in the global precoding code book.
The method of the present invention, wherein the step B2 further comprises the steps of:
the base station receives channel characteristic information from each user equipment and performs probability distribution analysis on CDD delay values matched with the channel characteristics;
and the base station selects Nt CDD delay values with the maximum probability as the CDD delay values in the global precoding code book.
The method of the present invention, wherein the channel characteristics include: at least one of direct path/non-direct path, fast fading/slow fading, flat fading/frequency selective fading;
the matching principle is as follows:
the channel of the direct path corresponds to a CDD delay value in a larger pre-coding code book, and the channel of the indirect path corresponds to a CDD delay value in a smaller pre-coding code book;
the fast fading channel corresponds to a large CDD delay value in the pre-coding code book, and the slow fading channel corresponds to a small CDD delay value in the pre-coding code book;
the flat fading channel corresponds to the CDD delay value in the larger precoding codebook, and the frequency selective fading channel corresponds to the CDD delay value in the smaller precoding codebook.
A system for determining a delay value of cyclic delay diversity comprises a base station and a plurality of user equipment; the base station includes: a precoding codebook module for storing a precoding codebook in combination with the CDD; the user equipment includes: a baseband demodulation module having a channel estimation sub-module; wherein:
the user equipment further comprises:
the channel characteristic judging module is used for judging channel characteristics according to a channel estimation result output by the channel estimation submodule and sending the obtained channel characteristic information to the base station;
the base station further comprises:
the feedback information receiving module is used for receiving the channel characteristic information sent by each user equipment;
and the probability analysis module is used for carrying out probability distribution analysis on the channel characteristics of each user equipment, selecting Nt CDD delay values matched with the channel characteristics with the maximum probability as global CDD delay values in the precoding codebook, and sending the CDD delay values to the precoding codebook module combined with CDD so as to update the CDD delay values in the precoding codebook.
In the system of the present invention, the probability analysis module in the base station is further configured to perform probability distribution analysis on CDD delay values matched with channel characteristics of each user equipment, select Nt CDD delay values with the highest probability as CDD delay values in the global precoding codebook, and send the CDD delay values to the CDD-combined precoding codebook module to update CDD delay values in the precoding codebook.
The system of the present invention, wherein the base station further includes: a starting update signal sending module, configured to send a starting signal for updating the CDD delay value to each user equipment;
the user equipment further comprises: and the starting updating signal receiving module is used for receiving the CDD delay value updating starting signal from the base station and starting the channel characteristic judging module.
The system of the present invention, wherein the user equipment further comprises: and the timing module is used for periodically generating and sending a CDD delay value start updating signal to the channel characteristic judging module.
A base station comprising a combined CDD precoding codebook module for storing a precoding codebook; further comprising:
the feedback information receiving module is used for receiving the channel characteristic information sent by each user equipment;
and the probability analysis module is used for carrying out probability distribution analysis on the channel characteristics of each user equipment, selecting Nt CDD delay values matched with the channel characteristics with the maximum probability as global CDD delay values in the precoding codebook, and sending the CDD delay values to the precoding codebook module combined with CDD so as to update the CDD delay values in the precoding codebook.
The base station of the present invention, wherein the probability analysis module is further configured to perform probability distribution analysis on CDD delay values matched with channel characteristics of each user equipment, select Nt CDD delay values with the highest probability as CDD delay values in the global precoding codebook, and send the CDD delay values to the CDD-combined precoding codebook module to update CDD delay values in the precoding codebook.
The base station of the present invention further comprises:
and the starting updating signal sending module is used for sending a starting signal for updating the CDD delay value to each user equipment.
A user equipment comprising a baseband demodulation module having a channel estimation sub-module, further comprising:
and the channel characteristic judging module is used for judging the channel characteristics according to the channel estimation result output by the channel estimation submodule and sending the obtained channel characteristic information to the base station.
The user equipment of the present invention further comprises:
and the starting updating signal receiving module is used for receiving the CDD delay value updating starting signal from the base station and starting the channel characteristic judging module.
The user equipment of the present invention further comprises:
and the timing module is used for periodically generating and sending a CDD delay value start updating signal to the channel characteristic judging module.
A method for determining delay value of cyclic delay diversity is used for precoding system of combining CDD including base station and several user equipments, including the steps:
c1, the user equipment respectively obtains the CDD delay value in the precoding code book which can obtain the optimal channel quality on each sub-band according to the channel estimation result, and feeds the CDD delay value back to the base station;
c2, the base station selects the CDD delay value in the optimal precoding code book for each user respectively according to the CDD delay value in the received local optimal precoding code book from each user equipment;
and C3, the base station updates the CDD delay value in the precoding code book according to the CDD delay value in the selected precoding code book.
The method of the present invention, wherein the step C1 further comprises the following steps:
the base station sends a starting signal to the user equipment, and starts the updating process of the CDD delay value in the precoding codebook, or the user equipment periodically and automatically starts the updating process of the CDD delay value in the precoding codebook.
The method of the present invention, wherein the step C1 further comprises the steps of:
the user equipment carries out channel estimation by using the pilot frequency information sent by the base station;
the user equipment respectively acquires the CDD delay value in the precoding codebook, which can obtain the maximum capacity, the maximum data rate or the minimum bit error rate, on each sub-band according to the channel estimation result;
and the user equipment sends the CDD delay value in the acquired local optimal precoding codebook to the base station.
In the method of the present invention, the ue obtains the CDD delay value in the precoding codebook that can obtain the optimal channel quality on each subband, and traverses and tests all possible CDD delay values in the preset CDD delay value range on each subband one by one to obtain the optimal CDD delay value that can enable the ue to obtain the optimal channel quality.
In the method of the present invention, the CDD delay value in the precoding codebook that can obtain the optimal channel quality is obtained by the user equipment on each sub-band, and the optimal CDD delay value corresponding to the optimal channel quality that can be obtained by the user equipment on each sub-band is obtained by calculation.
The method of the present invention, wherein the step C2 further comprises the steps of:
the base station receives CDD delay values in the local optimal precoding code books from the user equipment, and carries out probability distribution analysis on the CDD delay values in the local optimal precoding code books of the user equipment;
and the base station selects Nt CDD delay values with the maximum probability as the CDD delay values in the optimal precoding code book of the corresponding user.
The method of the present invention, wherein the step C1 further comprises the steps of:
the user equipment respectively acquires a CDD delay value in a precoding code book capable of obtaining the optimal channel quality on each sub-band according to the channel estimation result, and feeds the optimal CDD delay value and the corresponding channel quality back to the base station;
the step C2 further includes the steps of:
the base station receives CDD delay values and corresponding channel qualities in the local optimal precoding code books from the user equipment, and carries out probability distribution analysis on the channel qualities corresponding to the optimal CDD delay values of the user equipment;
and the base station selects Nt CDD delay values with the maximum channel quality probability as the CDD delay values in the optimal precoding code book of the corresponding user.
A system for determining a delay value of cyclic delay diversity comprises a base station and a plurality of user equipment; the base station includes: a precoding codebook module for storing a precoding codebook in combination with the CDD; the user equipment includes: a baseband demodulation module having a channel estimation sub-module; wherein,
the user equipment further comprises:
a CDD delay value obtaining module in the local optimal precoding codebook, configured to obtain, on each subband, a CDD delay value in the local optimal precoding codebook that can obtain the optimal channel quality according to a channel estimation result output by the channel estimation submodule, and send the CDD delay value in the local optimal precoding codebook to the base station;
the base station further comprises:
the feedback information receiving module is used for receiving CDD delay values in the local optimal precoding code books sent by each user equipment;
and the probability analysis module is used for respectively carrying out probability distribution analysis on the CDD delay values in the local optimal precoding codebook of each user equipment, selecting Nt CDD delay values with the maximum probability as the CDD delay values in the optimal precoding codebook of the corresponding user, and sending the CDD delay values to the CDD-combined precoding codebook module so as to update the CDD delay values in the precoding codebook.
The system of the present invention, wherein, the module for obtaining CDD delay value in local optimal precoding codebook in user equipment is further configured to obtain CDD delay value in local optimal precoding codebook capable of obtaining optimal channel quality on each sub-band according to the channel estimation result output by the channel estimation sub-module, and send the CDD delay value in local optimal precoding codebook and its corresponding channel quality to the base station;
a feedback information receiving module in the base station, further configured to receive CDD delay values in the local optimal precoding codebook sent by each user equipment and channel qualities corresponding to the CDD delay values;
the probability analysis module in the base station is further configured to perform probability distribution analysis on the channel quality corresponding to the optimal CDD delay value of each user equipment, select Nt CDD delay values with the largest channel quality probability as the optimal CDD delay values in the precoding codebook of the corresponding user, and send the CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
The system of the present invention, wherein the base station further includes: a starting update signal sending module, configured to send a starting signal for updating the CDD delay value to each user equipment;
the user equipment further comprises: and the starting updating signal receiving module is used for receiving the CDD delay value updating starting signal from the base station and starting the CDD delay value acquiring module in the local optimal precoding codebook.
The system of the present invention, wherein the user equipment further comprises: and the timing module is used for periodically generating and sending a CDD delay value starting updating signal to the CDD delay value acquisition module in the local optimal precoding codebook.
A base station comprising a combined CDD precoding codebook module for storing a precoding codebook; further comprising:
the feedback information receiving module is used for receiving CDD delay values in the local optimal precoding code books sent by each user equipment;
and the probability analysis module is used for respectively carrying out probability distribution analysis on the CDD delay values in the local optimal precoding codebook of each user equipment, selecting Nt CDD delay values with the maximum probability as the CDD delay values in the optimal precoding codebook of the corresponding user, and sending the CDD delay values to the CDD-combined precoding codebook module so as to update the CDD delay values in the precoding codebook.
The base station of the present invention, wherein the feedback information receiving module is further configured to receive CDD delay values in the local optimal precoding codebook sent by each user equipment and channel qualities corresponding to the CDD delay values;
the probability analysis module is further configured to perform probability distribution analysis on channel quality corresponding to the optimal CDD delay value of each user equipment, select Nt CDD delay values with the largest channel quality probability as the optimal CDD delay values in the precoding codebook of the corresponding user, and send the CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
The base station of the present invention further comprises:
and the starting updating signal sending module is used for sending a starting signal for updating the CDD delay value to each user equipment.
A method for determining delay value of cyclic delay diversity is used for precoding system of combining CDD including base station and several user equipments, including the steps:
d1, the user equipment judges the channel characteristics according to the channel estimation result and feeds back the obtained channel characteristic information to the base station;
d2, the base station selects the optimal CDD delay value in the precoding code book for each user respectively according to the received channel characteristic information from each user equipment;
d3, the base station updates the CDD delay value in the precoding code book according to the CDD delay value in the selected precoding code book.
The method of the present invention, wherein the step D1 further comprises the steps of:
the base station sends a starting signal to the user equipment, and starts the updating process of the CDD delay value in the precoding codebook, or the user equipment periodically and automatically starts the updating process of the CDD delay value in the precoding codebook.
The method of the present invention, wherein the step D2 further comprises the steps of:
the base station receives channel characteristic information from each user equipment and carries out probability distribution analysis on the channel characteristics of each user respectively;
and the base station selects Nt CDD delay values matched with the channel characteristics with the maximum probability as the CDD delay values in the optimal precoding code book of the corresponding user.
The method of the present invention, wherein the step D2 further comprises the steps of:
the base station receives channel characteristic information from each user device, and respectively performs probability distribution analysis on CDD delay values matched with the channel characteristics of each user;
and the base station selects Nt CDD delay values with the maximum probability as the CDD delay values in the optimal precoding code book of the corresponding user.
The method of the present invention, wherein the channel characteristics include: at least one of direct path/non-direct path, fast fading/slow fading, flat fading/frequency selective fading;
the matching principle is as follows:
the channel of the direct path corresponds to a CDD delay value in a larger pre-coding code book, and the channel of the indirect path corresponds to a CDD delay value in a smaller pre-coding code book;
the fast fading channel corresponds to a large CDD delay value in the pre-coding code book, and the slow fading channel corresponds to a small CDD delay value in the pre-coding code book;
the flat fading channel corresponds to the CDD delay value in the larger precoding codebook, and the frequency selective fading channel corresponds to the CDD delay value in the smaller precoding codebook.
A system for determining a delay value of cyclic delay diversity comprises a base station and a plurality of user equipment; the base station includes: a precoding codebook module for storing a precoding codebook in combination with the CDD; the user equipment includes: a baseband demodulation module having a channel estimation sub-module; wherein:
the user equipment further comprises:
the channel characteristic judging module is used for judging channel characteristics according to a channel estimation result output by the channel estimation submodule and sending the obtained channel characteristic information to the base station;
the base station further comprises:
the feedback information receiving module is used for receiving the channel characteristic information sent by each user equipment;
and the probability analysis module is used for respectively carrying out probability distribution analysis on the channel characteristics of each user equipment, selecting Nt CDD delay values matched with the channel characteristics with the maximum probability as the CDD delay values in the optimal precoding codebook of the corresponding user, and sending the CDD delay values to the precoding codebook module combined with CDD so as to update the CDD delay values in the precoding codebook.
In the system of the present invention, the probability analysis module in the base station is further configured to perform probability distribution analysis on the CDD delay values matched with the channel characteristics of each user equipment, select Nt CDD delay values with the highest probability as the CDD delay values in the optimal precoding codebook of the corresponding user, and send the CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
The system of the present invention, wherein the base station further includes: a starting update signal sending module, configured to send a starting signal for updating the CDD delay value to each user equipment;
the user equipment further comprises: and the starting updating signal receiving module is used for receiving the CDD delay value updating starting signal from the base station and starting the channel characteristic judging module.
The system of the present invention, wherein the user equipment further comprises: and the timing module is used for periodically generating and sending a CDD delay value start updating signal to the channel characteristic judging module.
A base station comprising a combined CDD precoding codebook module for storing a precoding codebook; further comprising:
the feedback information receiving module is used for receiving the channel characteristic information sent by each user equipment;
and the probability analysis module is used for respectively carrying out probability distribution analysis on the channel characteristics of each user equipment, selecting Nt CDD delay values matched with the channel characteristics with the maximum probability as the CDD delay values in the optimal precoding codebook of the corresponding user, and sending the CDD delay values to the precoding codebook module combined with CDD so as to update the CDD delay values in the precoding codebook.
In the base station of the present invention, the probability analysis module is further configured to perform probability distribution analysis on CDD delay values matched with channel characteristics of each user equipment, select Nt CDD delay values with the highest probability as CDD delay values in an optimal precoding codebook of a corresponding user, and send the CDD delay values to a precoding codebook module combined with CDD to update CDD delay values in the precoding codebook.
The base station of the present invention further comprises:
and the starting updating signal sending module is used for sending a starting signal for updating the CDD delay value to each user equipment.
A method for determining delay value of cyclic delay diversity is used for precoding system of combining CDD including base station and several user equipments, including the steps:
e1, periodically counting the cell performance of the base station;
e2, in each statistical period, the base station records the cell performance and the corresponding CDD delay value;
e3, the base station judges whether the cell performance is reduced according to the recorded cell performance of a plurality of periods, and when the cell performance is determined to be reduced, the CDD delay value in the precoding code book is updated.
The method of the invention, wherein the cell performance is at least one of average throughput, average error code performance, average time delay performance and boundary user throughput.
The method of the present invention, wherein,
in step E3, the CDD delay value in the updated precoding codebook is: according to the record information of the base station, the unused CDD delay value is selected to be updated.
The method of the present invention, wherein,
in step E3, the CDD delay value in the updated precoding codebook is: according to the record information of the base station, the CDD delay value with better performance in a past period is selected for updating.
A base station comprising a combined CDD precoding codebook module for storing a precoding codebook; wherein:
the system also comprises a CDD delay value updating module, a statistical result storage module and a cell performance statistical module;
the cell performance statistic module is used for periodically counting the cell performance and storing the cell performance and the corresponding CDD delay value into the statistic result storage module;
and the CDD delay value updating module is used for updating the CDD delay value in the precoding code book by using the result stored by the statistical result storage module.
The CDD delay value updating module is further configured to select an unused CDD delay value to update the CDD delay value in the precoding codebook according to the record information of the base station.
The CDD delay value updating module is further configured to select a CDD delay value with better performance in a past period of time according to the record information of the base station to update the CDD delay value in the precoding codebook.
A method for determining delay value of cyclic delay diversity is used for precoding system of combining CDD including base station and several user equipments, including the steps:
f1, the base station periodically counts the user performance;
f2, in each statistical period, the base station records the user performance and the corresponding CDD delay value;
f3, the base station judges whether the user performance is reduced according to the recorded cell performance of a plurality of periods, and when the user performance is determined to be reduced, the CDD delay value in the precoding code book of the corresponding user is updated.
The method of the present invention, wherein the user performance is at least one of average throughput, average error performance and average delay performance.
In step F3, the updating CDD delay values in the precoding code books of the corresponding users is as follows: according to the record information of the base station, the unused CDD delay value is selected to be updated.
In step F3, the updating CDD delay values in the precoding code books of the corresponding users is as follows: according to the record information of the base station, the CDD delay value with better performance in a past period is selected for updating.
A base station comprising a combined CDD precoding codebook module for storing a precoding codebook; wherein:
the system also comprises a CDD delay value updating module, a statistical result storage module and a user performance statistical module;
the user performance statistic module is used for periodically counting the user performance and storing the user performance and the corresponding CDD delay value into the statistic result storage module;
and the CDD delay value updating module is used for updating the CDD delay value in the precoding code book of the corresponding user by using the result stored by the statistical result storage module.
The CDD delay value updating module is further configured to select an unused CDD delay value according to the record information of the base station to update the CDD delay value in the precoding codebook of the corresponding user.
The CDD delay value updating module is further configured to select a CDD delay value with better performance in a past period of time according to the record information of the base station to update the CDD delay value in the precoding codebook of the corresponding user.
According to the method and the system, each user equipment obtains the optimal CDD delay value capable of obtaining the optimal channel quality on each sub-band according to the channel estimation result, so that the self-adaptive production of the optimal CDD delay value from the user equipment is realized; the base station performs probability analysis on the optimal CDD delay value or the optimal CDD delay value and the channel quality corresponding to the optimal CDD delay value from each user equipment to obtain the global optimal CDD delay value with the maximum probability distribution, so that the self-adaptive updating of the CDD delay value in the precoding code book in the precoding system combined with the CDD is realized, and the system performance is guaranteed to the maximum extent; the system and the method of the invention also lead the precoding system combining the CDD to more flexibly realize the self-adaptive updating of the CDD delay value in the precoding code book according to the system requirement by adopting the starting operation of the base station for starting the updating of the CDD delay value or the starting operation of the user equipment for automatically and periodically starting the updating of the CDD delay value.
Technical problems to be solved, technical scheme key points and beneficial effects of the present invention will be further explained with reference to the accompanying drawings in combination with embodiments.
Drawings
Fig. 1 is a schematic diagram of a transmitting end structure of a conventional precoding system;
FIG. 2 is a flow chart of the system according to embodiment 1;
FIG. 3 is a schematic diagram of a system configuration according to embodiment 1;
FIG. 4 is a schematic view of another system configuration of embodiment 1;
FIG. 5 is a flowchart of the system operation according to embodiment 2;
FIG. 6 is a schematic diagram of a system configuration according to embodiment 2;
FIG. 7 is a schematic view of another system configuration in embodiment 2;
FIG. 8 is a flowchart of the system according to embodiment 3;
FIG. 9 is a flowchart of the system according to embodiment 4;
FIG. 10 is a flowchart of the system according to embodiment 5;
fig. 11 is a schematic structural diagram of a transmitting end in embodiment 5;
FIG. 12 is a flowchart of the system operation according to embodiment 6;
fig. 13 is a schematic structural diagram of a transmitting end in embodiment 6.
Detailed Description
The first embodiment is as follows:
in this embodiment, a receiving end, that is, a User Equipment (UE), acquires CDD delay values (sets) in its own optimal precoding codebook and feeds back the CDD delay values (sets) to a Base Station (BS), and a transmitting end, that is, the base station, selects CDD delay values (sets) in a global precoding codebook according to the CDD delay values (sets) in the optimal precoding codebook from each UE, thereby implementing adaptive update of CDD delay values (sets) in the precoding codebook, and ensuring system performance to the maximum. Global here means that the CDD delay values (groups) in the same set of precoding codebooks apply to all users. For convenience of description, the CDD delay value and the set of CDD delay values are referred to as CDD delay values. Referring to fig. 2, in a multi-user scheduling MIMO-OFDMA system including a base station and a plurality of user equipments to which a precoding technique combined with CDD is applied, the method according to the embodiment of the present invention includes the following steps:
When the base station does not initiate the start of updating the CDD delay value again or the timing period of the periodic automatic start of the user equipment for updating the CDD delay value does not come, the user equipment does not need to update the CDD delay value and does not need to select the global CDD delay value by the base station.
In the above process, in step 202, the user equipment performs channel estimation by using pilot information sent by the base station, and according to the result of channel estimation, obtains the CDD delay value in the optimal precoding codebook on each subband respectively, and may adopt the following two methods:
the method comprises the following steps: through traversal search, the CDD delay values in all possible precoding codebooks are tested one by one within the possible value range of the delay value on each subband, so that the CDD delay value in the precoding codebook with the optimal channel quality (such as capacity, data rate, bit error rate and the like) obtained by the user is the optimal CDD delay value on the subband. The range of the delay value is [0, Nc-1], where Nc is the total number of subcarriers, and is periodic due to the operation of cyclic shift, so the range of the delay value can also be expressed as [ -Nc/2, Nc/2-1 ]. In a multi-user system, the value selected as the optimal CDD delay value is usually closer to 0, that is, the absolute value is smaller, so the value range of the delay value is expressed as [ -Nc/2, Nc/2-1], and thus the search range can be reduced, thereby reducing the complexity.
The method 2 comprises the following steps: and calculating to obtain the CDD delay value in the precoding code book which enables the channel quality obtained by the user to be optimal. The capacity is taken as an example to explain how to obtain the optimal CDD delay value by calculation.
And calculating the capacity obtained by the user equipment on each sub-band through a capacity calculation expression as follows:
CM(d1，…，dNt)＝f(H，U，d1，…，dNt)
wherein, CMDenotes capacity on the Mth subband, H denotes channel response from a transmitting antenna to a receiving antenna by channel estimation, diIndicating the CDD delay value in the precoding code book corresponding to the ith transmitting antenna, and Nt indicating the number of the transmitting antennas; in a CDD-combined precoding codebook, the codebook
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Where Nc denotes the number of all subcarriers, the diagonal matrix is the codebook part of CDD in the precoding codebook, and U is precodingThe codebook part designed by the traditional method in the coding has different U forms under different working modes (such as a single-user diversity mode, a single-user spatial multiplexing mode and a multi-user spatial multiplexing mode). By optimizing CMThe optimal CDD delay value in the precoding codebook can be obtained, for example, by performing optimization calculation through the lagrangian algorithm.
The user equipment can obtain the CDD delay value in the precoding codebook ensuring the channel quality to be optimal on each sub-band by any one of the above two methods. Then, the user equipment feeds back the CDD delay values in the local optimal precoding codebooks or the CDD delay values in the local optimal precoding codebooks and the corresponding channel quality to the base station.
In this embodiment, the base station selects the CDD delay value in the global precoding codebook according to the collected CDD delay value in the local optimal precoding codebook from each user equipment or the CDD delay value in the local optimal precoding codebook and the corresponding channel quality thereof, and may measure and select the CDD delay value in the global precoding codebook in a variety of ways. Only two methods are listed below as examples:
the method comprises the following steps: and selecting according to the probability density distribution condition of the CDD delay values in the local optimal precoding code book fed back by the user equipment in different feedback periods in the same updating process.
Suppose { d (i)UE，iSB，iInterval)，iUE＝1，…，NUE，iSB＝1，…，NSB，iInterval＝1，…，NIntervalThe set of CDD delay values in the precoding codebook fed back by the user in different feedback periods in the same updating process, wherein iUEFor user equipment index, iSBFor subband index, iIntervalFor time domain feedback period index, NUENumber of users participating in feedback, NSBIs the number of sub-bands, NIntervalIs the number of feedback cycles in an update process. Based on this set, the base station draws { d (i) } (i)UE，iSB，iInterval)，iUE＝1，…，NUE，iSB＝1，…，NSB，iInterval＝1，…，NIntervalThe probability density distribution function takes the Nt (number of transmitting antennas) CDD delay values corresponding to the highest probability as the CDD delay values in the global precoding codebook. The CDD delay value obtained in this way has the maximum probability of being selected as the optimal CDD delay value by different users, so that the performance gain can be provided, and the system performance is guaranteed.
The method 2 comprises the following steps: and selecting according to the probability density distribution condition of the channel quality by using the CDD delay value in the local optimal precoding codebook fed back by the user equipment in different feedback periods in the same updating process and the corresponding channel quality.
When the method is adopted, the user equipment feeds back the optimal CDD delay value to the base station and simultaneously feeds back the channel quality corresponding to the optimal CDD delay value. Here, let { d (i) }UE，iSB，iInterval)，iUE＝1，…，NUE，iSB＝1，…，NSB，iInterval＝1，…，NIntervalSet of locally optimal CDD delay values for user feedback, { C (i } { C (i })UE，iSB，iInterval)，iUE＝1，…，NUE，iSB＝1，…，NSB，iInterval＝1，…，NIntervalCorresponding to { d (i) } for user feedbackUE，iSB，iInterval)，iUE＝1，…，NUE，iSB＝1，…，NSB，iInterval＝1，…，NIntervalThe CQI of. Based on these two sets, the base station first calculates C (d)i)，
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Indicating and precoding the CDD delay value in the codebook as diCorresponding CQI sum, and then plotting { C (d)i) Will correspond to C (d)i) The highest Nt (number of transmission antennas) CDD delay values are used as CDD delay values in the global precoding codebook. The CDD delay value in the global precoding codebook obtained in the way can provide a larger CQI for the system with the maximum probability, thereby providing performance gain and ensuring the system performance.
Referring to fig. 3, the system for initiating the CDD delay value updating operation in the precoding codebook by the base station according to the embodiment of the present invention includes: a base station, and a plurality of user equipments (only the structure of one user equipment is specifically shown in fig. 3, and other user equipments are similar and are not described again one by one).
Wherein the receiving end, i.e. each user equipment, comprises: the device comprises a receiving antenna, a baseband demodulation module with a channel estimation sub-module, a CDD delay value acquisition module in a local optimal precoding codebook and a starting updating signal receiving module.
The receiving antenna is used for receiving signals from a base station;
the channel estimation submodule is used for carrying out channel estimation according to the pilot frequency information sent by the base station;
the starting updating signal receiving module is used for receiving a CDD delay value updating starting signal from the base station and starting the CDD delay value obtaining module in the local optimal precoding codebook;
the CDD delay value obtaining module in the local optimal precoding codebook is configured to, after receiving the start signal, respectively obtain, on each sub-band, a CDD delay value in the local optimal precoding codebook that can obtain the optimal channel quality according to a channel estimation result output by the channel estimation submodule, and send the CDD delay value in the local optimal precoding codebook or the CDD delay value in the local optimal precoding codebook and the channel quality corresponding to the CDD delay value in the local optimal precoding codebook to the base station.
The transmitting end, i.e., the base station, includes: the device comprises a scheduling module, a demultiplexing module, a pre-coding module, a serial-parallel conversion module, an inverse Fourier transform module, a cyclic prefix inserting module, a sending antenna, a pre-coding codebook module combined with CDD, a starting updating signal sending module, a feedback information receiving module and a probability analysis module.
The scheduling module is configured to perform scheduling of radio resources for multiple users according to feedback information (e.g., CQI) of the users, and allocate resources such as time, frequency, space, and code to different users;
the demultiplexing module is used for respectively sending the data streams to different antenna branches;
the precoding module is configured to perform precoding operation on the data stream, that is, perform weighting operation on data symbols of different antenna branches;
the serial-parallel conversion module is used for converting serial data streams into parallel data streams;
the inverse Fourier transform module is used for performing inverse Fourier transform on the parallel data streams and transforming the signals from a frequency domain to a time domain;
the cyclic prefix inserting module is used for inserting a cyclic prefix into the data which passes through the inverse Fourier transform module;
the transmitting antenna is used for transmitting the analog signal;
the CDD-combined precoding codebook module is used for storing a precoding codebook comprising a plurality of codebooks and carrying out precoding operation on data by selecting an optimal codebook from the precoding codebook;
the starting updating signal sending module is used for sending a starting signal for updating the CDD delay value to each user equipment;
the feedback information receiving module is used for receiving CDD delay values in the local optimal precoding codebook sent by each user equipment or CDD delay values in the local optimal precoding codebook and the corresponding channel quality;
and the probability analysis module is used for performing probability analysis by using the feedback information received by the feedback information receiving module so as to select the CDD delay value in the global precoding codebook and sending the CDD delay value to the precoding codebook module combined with the CDD so as to update the CDD delay value in the precoding codebook.
In the system described in this embodiment, after the start update signal sending module in the base station sends the start signal for updating the CDD delay value to each user equipment, the start update signal receiving module in each user equipment receives the start signal and starts the CDD delay value obtaining module in the local optimal precoding codebook. At this time, the CDD delay value obtaining module in the local optimal precoding codebook respectively obtains, according to the channel estimation result output by the channel estimation submodule, a CDD delay value in the precoding codebook that enables the channel quality obtained by the user to be optimal on each sub-band, and sends the CDD delay value in the local optimal precoding codebook to the feedback information receiving module in the base station, then, the feedback information receiving module sends the received local optimal precoding codebook CDD delay value or the local optimal precoding codebook CDD delay value from each user equipment and the corresponding channel quality thereof to the probability analysis module, and the probability analysis module performs probability distribution analysis on the CDD delay values in the local optimal precoding codebooks of each user equipment, and selects Nt (number of sending antennas) CDD delay values with the maximum probability. Then, the probability analysis module sends the selected Nt CDD delay values to a pre-coding codebook module combined with CDD, and the CDD delay values in the pre-coding codebook are updated. Or the probability analysis module performs probability distribution analysis on the channel quality corresponding to the CDD delay value in the local optimal precoding codebook of each user equipment, selects Nt CDD delay values with the maximum channel quality probability, and sends the Nt CDD delay values to the precoding codebook module combined with CDD to update the CDD delay value in the precoding codebook.
For the method described in the embodiment of fig. 2, the method can also be implemented by using a system as shown in fig. 4, where the system is implemented by the user equipment periodically and automatically starting the CDD delay value updating process in the precoding codebook. The system described in the embodiment of fig. 4 differs from the system described in the embodiment of fig. 3 in that: in fig. 4, a timing module in the user equipment periodically generates and sends the start signal to the CDD delay value acquisition module in the local optimal precoding codebook, where the timing modules of different users may be synchronous or asynchronous. At this time, the base station does not need to be provided with a starting updating signal sending module. How to obtain the CDD delay value in the local optimal precoding codebook for the user equipment, and how to select the CDD delay value in the global precoding codebook for the base station are similar to the system described in fig. 3, and other working flows of the system are also similar to the system described in fig. 3, and therefore, details are not repeated here.
Example two:
in this embodiment, the receiving end, i.e., the user equipment, acquires its own channel characteristic information, and then the transmitting end, i.e., the base station, reasonably selects the CDD delay value in the global precoding codebook according to the collected channel characteristic information from each user equipment, so as to implement adaptive update of the CDD delay value in the precoding codebook, thereby ensuring the system performance to the maximum extent. Referring to fig. 5, in a multi-user scheduling MIMO-OFDMA system including a base station and a plurality of user equipments to which a precoding technique combined with CDD is applied, the method according to the embodiment of the present invention includes the following steps:
and 505, the system normally works under the CDD delay value in the updated precoding codebook.
When the base station does not initiate the start of updating the CDD delay value again or the timing period of the periodic automatic start of the user equipment for updating the CDD delay value does not come, the user equipment does not need to update the CDD delay value and does not need to select the global CDD delay value by the base station.
In the above process, in step 502, the ue performs channel estimation by using pilot information sent by the base station, and determines channel characteristics according to a channel estimation result, where the channel characteristic information may include:
a direct path (LOS) and a non-direct path (NLOS), wherein the direct path is a path which can perform linear transmission due to the fact that no obstacle exists between a transmitting end and a receiving end, and therefore a relatively constant component is contained in channel response; the non-direct path means that there is an obstacle between the transmitting end and the receiving end, and thus there is no component of the straight line transmission.
Fast fading (fast fading), which means that the channel response changes rapidly in the time domain and is caused by the rapid movement of the user, and slow fading (slow fading); slow fading is that the channel response changes slowly in the time domain, and the correlation between the channel responses at adjacent times is strong, which is caused by the slow movement of the user.
Flat fading (flat fading) and frequency-selective fading (frequency-selective fading), where flat fading refers to relatively flat frequency domain response of a channel, that is, a small number of multipaths respond in a time domain of the channel; frequency selective fading refers to that the frequency domain response of a channel varies strongly with frequency, i.e., the channel response has more multipath in the time domain.
Regardless of the channel characteristic information, it can be transmitted to the base station by simple coding. And the base station reasonably selects the CDD delay value in the global precoding codebook according to the collected channel characteristic information from each user equipment.
The CDD delay values in the appropriate precoding codebook corresponding to different channel characteristics are different, as follows:
for the direct path and the non-direct path, the channel of the direct path is suitable for using a larger CDD delay value in the precoding code book; the non-direct path is suitable for using smaller CDD delay values in the precoding codebook.
For fast fading and slow fading, a fast fading channel is suitable for using a larger CDD delay value in a precoding codebook; slow fading is suitable for using the CDD delay values in smaller precoding codebooks.
For flat fading and frequency selective fading, a flat fading channel is suitable for using a large CDD delay value in a precoding codebook; frequency selective fading is suitable for using the CDD delay values in the smaller precoding codebook.
In step 503, the base station reasonably selects the CDD delay value in the global precoding codebook by using the channel characteristic information from each user equipment collected in different feedback periods in the updating process, and may adopt the following two methods:
the method comprises the following steps: the base station analyzes the probability distribution of different channel characteristics according to the channel characteristic information fed back by the user, and selects the CDD delay values in the precoding codebook according to the three relations for the channel characteristic information with the maximum probability, that is, selects Nt CDD delay values matched with the channel characteristic with the maximum probability as the CDD delay values in the global precoding codebook.
The method 2 comprises the following steps: the base station firstly judges which CDD delay value (a larger CDD delay value or a smaller CDD delay value) in the precoding code book the channel of each user is suitable for according to the channel characteristic information fed back by the user, then analyzes the probability distribution of the larger CDD delay value and the smaller CDD delay value, and selects Nt CDD delay values with the largest probability as the CDD delay values in the global precoding code book.
Referring to fig. 6, the system for initiating the CDD delay value updating operation in the precoding codebook by the base station according to the embodiment of the present invention includes: a base station, and a plurality of user equipments (only the structure of one user equipment is specifically shown in fig. 6, and other user equipments are similar and are not described again one by one).
Wherein the receiving end, i.e. each user equipment, comprises: the system comprises a receiving antenna, a baseband demodulation module with a channel estimation submodule, a channel characteristic judgment module and a start updating signal receiving module.
The receiving antenna is used for receiving signals from a base station;
the channel estimation submodule is used for carrying out channel estimation according to the pilot frequency information sent by the base station;
the starting updating signal receiving module is used for receiving a CDD delay value updating starting signal from a base station and starting the channel characteristic judging module;
and the channel characteristic judging module is used for judging the channel characteristics according to the channel estimation result output by the channel estimation submodule after receiving the starting signal and sending the obtained channel characteristic information to the base station.
The transmitting end, i.e., the base station, includes: the device comprises a scheduling module, a demultiplexing module, a pre-coding module, a serial-parallel conversion module, an inverse Fourier transform module, a cyclic prefix inserting module, a sending antenna, a pre-coding codebook module combined with CDD, a starting updating signal sending module, a feedback information receiving module and a probability analysis module.
The scheduling module is configured to perform scheduling of radio resources for multiple users according to feedback information (e.g., CQI) of the users, and allocate resources such as time, frequency, space, and code to different users;
the demultiplexing module is used for respectively sending the data streams to different antenna branches;
the precoding module is configured to perform precoding operation on the data stream, that is, perform weighting operation on data symbols of different antenna branches;
the serial-parallel conversion module is used for converting serial data streams into parallel data streams;
the inverse Fourier transform module is used for performing inverse Fourier transform on the parallel data streams and transforming the signals from a frequency domain to a time domain;
the cyclic prefix inserting module is used for inserting a cyclic prefix into the data which passes through the inverse Fourier transform module;
the transmitting antenna is used for transmitting the analog signal;
the CDD-combined precoding codebook module is used for storing a precoding codebook comprising a plurality of codebooks and carrying out precoding operation on data by selecting an optimal codebook from the precoding codebook;
the starting updating signal sending module is used for sending a starting signal for updating the CDD delay value to each user equipment;
the feedback information receiving module is used for receiving the channel characteristic information sent by each user equipment;
and the probability analysis module is used for performing probability analysis by using the channel characteristic information received by the feedback information receiving module so as to select the CDD delay value in the global precoding codebook and sending the CDD delay value to the precoding codebook module combined with CDD so as to update the CDD delay value in the precoding codebook.
In the system described in this embodiment, after the start update signal sending module in the base station sends the start signal for updating the CDD delay value to each user equipment, the start update signal receiving module in each user equipment receives the start signal and starts the channel characteristic determining module. At this time, the channel characteristic determining module determines the channel characteristic information of the user according to the channel estimation result output by the channel estimation submodule, and sends the obtained channel characteristic information to the feedback information receiving module in the base station, then the feedback information receiving module sends the received channel characteristic information from each user equipment to the probability analysis module, the probability analysis module performs probability distribution analysis on the channel characteristic of each user equipment, and selects Nt (number of sending antennas) CDD delay values matched with the channel characteristic with the maximum probability. Then, the probability analysis module sends the selected Nt CDD delay values to a pre-coding codebook module combined with CDD, and the CDD delay values in the pre-coding codebook are updated. Or the probability analysis module carries out probability distribution analysis on the CDD delay values matched with the channel characteristics of each user equipment, selects Nt CDD delay values with the maximum probability, and sends the Nt CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
For the method described in the embodiment of fig. 5, the method can also be implemented by using a system as shown in fig. 7, where the system is implemented by the user equipment periodically and automatically starting the CDD delay value updating process in the precoding codebook. The system described in the embodiment of fig. 7 differs from the system described in the embodiment of fig. 6 in that: in fig. 7, a timing module periodically generates and sends a start signal to the channel characteristic determination module in the user equipment, where the timing modules of different users may be synchronous or asynchronous. At this time, the base station does not need to be provided with a starting updating signal sending module. Here, how to select the CDD delay value in the global precoding codebook by the base station is similar to the system described in fig. 6, and other work flows of the system are also similar to the system described in fig. 6, and therefore, details are not repeated here.
Example three:
in this embodiment, a receiving end, that is, a user equipment, obtains a CDD delay value in an optimal precoding codebook of the user equipment, and feeds the CDD delay value back to a base station, and a sending end, that is, the base station, selects the CDD delay value in the optimal precoding codebook for each user according to the CDD delay value in the optimal precoding codebook collected from each user equipment, so as to implement adaptive update of the CDD delay value in the precoding codebook, and update of the CDD delay value in the precoding codebook is performed independently for each user, thereby ensuring system performance to the maximum extent. Referring to fig. 8, in a multi-user scheduling MIMO-OFDMA system including a base station and a plurality of user equipments to which a precoding technique combined with CDD is applied, the method according to the embodiment of the present invention includes the following steps:
When the base station does not initiate the start of updating the CDD delay value again or the timing period of the periodic automatic start of the user equipment for updating the CDD delay value does not come, the user equipment does not need to update the CDD delay value and does not need to select the CDD delay value by the base station. In the normal working process, for the data of the scheduled user, the base station uses the CDD delay value in the precoding code book corresponding to the user to process the data.
In the above process, in step 802, the user equipment performs channel estimation by using pilot information sent by the base station, and according to the result of channel estimation, obtains the CDD delay value in the optimal precoding codebook on each subband respectively, and may adopt the following two methods:
the method comprises the following steps: through traversal search, the CDD delay values in all possible precoding codebooks are tested one by one within the possible value range of the delay value on each subband, so that the CDD delay value in the precoding codebook with the optimal channel quality (such as capacity, data rate, bit error rate and the like) obtained by the user is the optimal CDD delay value on the subband. The range of the delay value is [0, Nc-1], where Nc is the total number of subcarriers, and is periodic due to the operation of cyclic shift, so the range of the delay value can also be expressed as [ -Nc/2, Nc/2-1 ]. In a multi-user system, the value selected as the optimal CDD delay value is usually closer to 0, that is, the absolute value is smaller, so the value range of the delay value is expressed as [ -Nc/2, Nc/2-1], and thus the search range can be reduced, thereby reducing the complexity.
The method 2 comprises the following steps: and calculating to obtain the CDD delay value in the precoding code book which enables the channel quality obtained by the user to be optimal. The capacity is taken as an example to explain how to obtain the optimal CDD delay value by calculation.
And calculating the capacity obtained by the user equipment on each sub-band through a capacity calculation expression as follows:
CM(d1，…，dNt)＝f(H，U，d1，…，dNt)
wherein, CMDenotes the M thCapacity on each subband, H denotes the channel response from the transmitting antenna to the receiving antenna obtained by channel estimation, diIndicating the CDD delay value in the precoding code book corresponding to the ith transmitting antenna, and Nt indicating the number of the transmitting antennas; in a CDD-combined precoding codebook, the codebook
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Where Nc denotes the number of all subcarriers, the diagonal matrix is the codebook part of CDD in the precoding codebook, U is the codebook part designed by the conventional method in precoding, and the form of U is different in different operating modes (e.g., single-user diversity mode, single-user spatial multiplexing mode, multi-user spatial multiplexing mode). By optimizing CMThe optimal CDD delay value in the precoding codebook can be obtained, for example, by performing optimization calculation through the lagrangian algorithm.
The user equipment can obtain the CDD delay value in the precoding codebook ensuring the channel quality to be optimal on each sub-band by any one of the above two methods. Then, the user equipment feeds back the CDD delay values in the local optimal precoding codebooks or the CDD delay values in the local optimal precoding codebooks and the corresponding channel quality to the base station.
In this embodiment, the base station selects an optimal CDD delay value in the precoding codebook for each user according to the collected CDD delay value in the local optimal precoding codebook from each user equipment or the CDD delay value in the local optimal precoding codebook and the corresponding channel quality, and may measure and select in various ways. Only two methods are listed below as examples:
the method comprises the following steps: and selecting according to the probability density distribution condition of the CDD delay values in the local optimal precoding code book fed back by each user equipment in different feedback periods in the same updating process.
Suppose { diUE(iSB，iInterval)，iSB＝1，…，NSB，iInterval＝1，…，NIntervalI is the user i in different feedback periods in the same updating processUESet of CDD delay values in the fed-back precoding codebook, wherein iUEFor user equipment index, iSBFor subband index, iIntervalFor time domain feedback period index, NSBIs the number of sub-bands, NIntervalIs the number of feedback cycles in an update process. Based on the set, the base station draws { diUE(iSB，iInterval)，iSB＝1，…，NSB，iInterval＝1，…，NIntervalThe probability density distribution function of the user i takes the Nt CDD delay values corresponding to the highest probability as the user iUEThe optimal CDD delay value in the precoding codebook. The CDD delay value thus obtained has the value of the delay of the user iUEThe maximum probability of the optimal CDD delay value is selected, so that the performance gain can be provided, and the system performance is guaranteed.
The method 2 comprises the following steps: and selecting according to the probability density distribution condition of the channel quality by using the CDD delay value in the local optimal precoding codebook fed back by the user equipment in different feedback periods in the same updating process and the corresponding channel quality.
When the method is adopted, the user equipment feeds back the optimal CDD delay value to the base station and simultaneously feeds back the channel quality corresponding to the optimal CDD delay value. Here, let { diUE(iSB，iInterval)，iSB＝1，…，NSB，iInterval＝1，…，NIntervalIs user iUESet of locally optimal CDD delay values for feedback, { CiUE(iSB，iInterval)，iSB＝1，…，NSB，iInterval＝1，…，NIntervalIs user iUEOf feedback corresponding to { diUE(iSB，iInterval)，iSB＝1，…，NSB，iInterval＝1，…，NIntervalThe CQI of. Based on these two sets, the base station first calculates C (d)i)，
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Indicating and precoding the CDD delay value in the codebook as diCorresponding CQI sum, and then plotting { C (d)i) Will correspond to C (d)i) The highest Nt CDD delay values as user iUEThe optimal CDD delay value in the precoding codebook. Thus obtained user iUECan make the user i have the maximum probabilityUEProviding a larger CQI for the system, thereby providing performance gain and ensuringThe system performance.
For each user, using one of the above two methods, an optimal CDD delay value in the precoding codebook for each user can be obtained.
The system for initiating the CDD delay value updating operation in the precoding codebook by the base station according to the embodiment of the present invention may adopt the same structure as in fig. 3, including: a base station and a plurality of user equipment.
The structure of the receiving end is completely the same as that of the corresponding part in the first embodiment, that is:
each user equipment includes: the device comprises a receiving antenna, a baseband demodulation module with a channel estimation sub-module, a CDD delay value acquisition module in a local optimal precoding codebook and a starting updating signal receiving module.
The receiving antenna is used for receiving signals from a base station;
the channel estimation submodule is used for carrying out channel estimation according to the pilot frequency information sent by the base station;
the starting updating signal receiving module is used for receiving a CDD delay value updating starting signal from the base station and starting the CDD delay value obtaining module in the local optimal precoding codebook;
the CDD delay value obtaining module in the local optimal precoding codebook is configured to, after receiving the start signal, respectively obtain, on each sub-band, a CDD delay value in the local optimal precoding codebook that can obtain the optimal channel quality according to a channel estimation result output by the channel estimation submodule, and send the CDD delay value in the local optimal precoding codebook or the CDD delay value in the local optimal precoding codebook and the channel quality corresponding to the CDD delay value in the local optimal precoding codebook to the base station.
The transmitting end, i.e. the base station, has the same basic structure as the corresponding module in the first embodiment, and includes: the device comprises a scheduling module, a demultiplexing module, a pre-coding module, a serial-parallel conversion module, an inverse Fourier transform module, a cyclic prefix inserting module, a sending antenna, a pre-coding codebook module combined with CDD, a starting updating signal sending module, a feedback information receiving module and a probability analysis module.
The scheduling module is configured to perform scheduling of radio resources for multiple users according to feedback information (e.g., CQI) of the users, and allocate resources such as time, frequency, space, and code to different users;
the demultiplexing module is used for respectively sending the data streams to different antenna branches;
the precoding module is configured to perform precoding operation on the data stream, that is, perform weighting operation on data symbols of different antenna branches;
the serial-parallel conversion module is used for converting serial data streams into parallel data streams;
the inverse Fourier transform module is used for performing inverse Fourier transform on the parallel data streams and transforming the signals from a frequency domain to a time domain;
the cyclic prefix inserting module is used for inserting a cyclic prefix into the data which passes through the inverse Fourier transform module;
the transmitting antenna is used for transmitting the analog signal;
the CDD-combined precoding codebook module is used for storing a precoding codebook comprising a plurality of codebooks and carrying out precoding operation on data by selecting an optimal codebook from the precoding codebook;
the starting updating signal sending module is used for sending a starting signal for updating the CDD delay value to each user equipment;
the feedback information receiving module is configured to receive a CDD delay value in the local optimal precoding codebook or a CDD delay value in the local optimal precoding codebook sent by each user equipment and a channel quality corresponding to the CDD delay value.
Here, the probability analysis module is different from the corresponding module in the first embodiment, and the difference is that: in this embodiment, the probability analysis module performs probability analysis on the feedback information of each user by using the feedback information received by the feedback information receiving module, so as to select an optimal CDD delay value in the precoding codebook for each user.
In the system described in this embodiment, after the start update signal sending module in the base station sends the start signal for updating the CDD delay value to each user equipment, the start update signal receiving module in each user equipment receives the start signal and starts the CDD delay value obtaining module in the local optimal precoding codebook.
At this time, the CDD delay value obtaining module in the local optimal precoding codebook respectively obtains the CDD delay value in the precoding codebook that enables the channel quality obtained by the user to be optimal on each sub-band according to the channel estimation result output by the channel estimation submodule, and sends the CDD delay value in the local optimal precoding codebook to the feedback information receiving module in the base station, then, the feedback information receiving module sends the received local optimal precoding codebook CDD delay value or the local optimal precoding codebook CDD delay value from each user equipment and the corresponding channel quality thereof to the probability analysis module, and the probability analysis module independently performs probability distribution analysis on the CDD delay value in the local optimal precoding codebook of each user equipment, and selects Nt CDD delay values with the largest probability for each user. Then, the probability analysis module sends the Nt CDD delay values selected for each user to the precoding codebook module combined with CDD to update the CDD delay values in the precoding codebook. Or the probability analysis module performs probability distribution analysis on the channel quality corresponding to the CDD delay value in the optimal precoding codebook of each user equipment independently, selects Nt CDD delay values corresponding to the channel quality with the highest probability for each user, and sends the values to the precoding codebook module combined with CDD to update the CDD delay values in the precoding codebook. In the normal working process, for the data of the scheduled user, the base station uses the CDD delay value in the precoding code book corresponding to the user to process the data.
For the method described in the embodiment in fig. 8, it can also be implemented by using the system shown in fig. 4, please refer to the above description, in this embodiment, the function of the probability analysis module is different from that of the probability analysis module in the first embodiment, and the system is that the user equipment periodically and automatically starts the CDD delay value updating process in the precoding codebook (via the timing module).
Example four:
in this embodiment, the receiving end, i.e., the user equipment, acquires its own channel characteristic information, and then the transmitting end, i.e., the base station, reasonably selects the optimal CDD delay value in the precoding codebook for each user according to the collected channel characteristic information from each user equipment, so as to implement adaptive update of the CDD delay value in the precoding codebook, thereby ensuring the system performance to the maximum extent. Referring to fig. 9, in a multi-user scheduling MIMO-OFDMA system including a base station and a plurality of user equipments to which a precoding technique combined with CDD is applied, the method according to the embodiment of the present invention includes the following steps:
step 901, the base station sends a start signal to the user equipment to start an updating process of the CDD delay value in the precoding codebook, or the user equipment periodically and automatically starts the updating process of the CDD delay value in the precoding codebook;
step 902, in each feedback period, the user equipment performs channel estimation by using pilot frequency information sent by the base station, judges channel characteristics according to a channel estimation result, and feeds back the obtained channel characteristic information to the base station;
step 903, the base station reasonably selects the optimal CDD delay value in the precoding codebook for each user respectively by using the channel characteristic information from each user equipment collected in different feedback periods in the updating process;
step 904, the base station updates the CDD delay value in the precoding codebook according to the CDD delay value in the selected precoding codebook, and notifies each user equipment;
step 905, the system works normally under the updated CDD delay value in the precoding codebook.
When the base station does not initiate the start of updating the CDD delay value again or the timing period of the periodic automatic start of the user equipment for updating the CDD delay value does not come, the user equipment does not need to update the CDD delay value and does not need to select the global CDD delay value by the base station.
In the above process, in step 902, the ue performs channel estimation by using pilot information sent by the base station, and determines channel characteristics according to a channel estimation result, where the channel characteristic information may include:
the direct path and the non-direct path are adopted, and the direct path is a straight line transmission path because no obstacle exists between the transmitting end and the receiving end, so that a relatively constant component is contained in channel response; the non-direct path means that there is an obstacle between the transmitting end and the receiving end, and thus there is no component of the straight line transmission.
Fast fading and slow fading, wherein fast fading refers to rapid change of channel response in a time domain and is caused by rapid movement of a user; slow fading is that the channel response changes slowly in the time domain, and the correlation between the channel responses at adjacent times is strong, which is caused by the slow movement of the user.
Flat fading and frequency selective fading, wherein the flat fading means that the frequency domain response of a channel is relatively flat, that is, the number of multipaths responding in the time domain of the channel is relatively small; frequency selective fading refers to that the frequency domain response of a channel varies strongly with frequency, i.e., the channel response has more multipath in the time domain.
Regardless of the channel characteristic information, it can be transmitted to the base station by simple coding. And the base station reasonably selects the optimal CDD delay value in the precoding code book for each user respectively according to the collected channel characteristic information from each user device.
The CDD delay values in the appropriate precoding codebook corresponding to different channel characteristics are different, as follows:
for the direct path and the non-direct path, the channel of the direct path is suitable for using a larger CDD delay value in the precoding code book; the non-direct path is suitable for using smaller CDD delay values in the precoding codebook.
For fast fading and slow fading, a fast fading channel is suitable for using a larger CDD delay value in a precoding codebook; slow fading is suitable for using the CDD delay values in smaller precoding codebooks.
For flat fading and frequency selective fading, a flat fading channel is suitable for using a large CDD delay value in a precoding codebook; frequency selective fading is suitable for using the CDD delay values in the smaller precoding codebook.
In step 903, the base station reasonably selects an optimal CDD delay value in the precoding codebook for each user by using the channel characteristic information from each user equipment collected in different feedback periods in the updating process, and may adopt the following two methods:
the method comprises the following steps: the base station analyzes the probability distribution of different channel characteristics for each user according to the channel characteristic information fed back by the user, and selects the optimal CDD delay value in the precoding codebook for each user according to the three relations for the channel characteristic information with the maximum probability, namely selects Nt CDD delay values matched with the channel characteristics with the maximum probability as the optimal CDD delay values in the precoding codebook for the corresponding user.
The method 2 comprises the following steps: the base station firstly judges the CDD delay value (larger CDD delay value or smaller CDD delay value) in which precoding code book the channel of each user is suitable for according to the channel characteristic information fed back by the user, then independently analyzes the probability distribution of the larger CDD delay value and the smaller CDD delay value of each user, and selects Nt CDD delay values with the maximum probability as the CDD delay value in the optimal precoding code book of the corresponding user.
The system for initiating the CDD delay value updating operation in the precoding codebook by the base station according to the embodiment of the present invention may adopt the same structure as in fig. 6, including: a base station and a plurality of user equipment.
Wherein, the structure of the receiving end is completely the same as that of the corresponding part in the second embodiment, namely:
each user equipment includes: the system comprises a receiving antenna, a baseband demodulation module with a channel estimation submodule, a channel characteristic judgment module and a start updating signal receiving module.
The receiving antenna is used for receiving signals from a base station;
the channel estimation submodule is used for carrying out channel estimation according to the pilot frequency information sent by the base station;
the starting updating signal receiving module is used for receiving a CDD delay value updating starting signal from a base station and starting the channel characteristic judging module;
and the channel characteristic judging module is used for judging the channel characteristics according to the channel estimation result output by the channel estimation submodule after receiving the starting signal and sending the obtained channel characteristic information to the base station.
The transmitting end, i.e. the base station, has the same basic structure as the corresponding module in the second embodiment, and includes: the device comprises a scheduling module, a demultiplexing module, a pre-coding module, a serial-parallel conversion module, an inverse Fourier transform module, a cyclic prefix inserting module, a sending antenna, a pre-coding codebook module combined with CDD, a starting updating signal sending module, a feedback information receiving module and a probability analysis module.
The scheduling module is configured to perform scheduling of radio resources for multiple users according to feedback information (e.g., CQI) of the users, and allocate resources such as time, frequency, space, and code to different users;
the demultiplexing module is used for respectively sending the data streams to different antenna branches;
the precoding module is configured to perform precoding operation on the data stream, that is, perform weighting operation on data symbols of different antenna branches;
the serial-parallel conversion module is used for converting serial data streams into parallel data streams;
the inverse Fourier transform module is used for performing inverse Fourier transform on the parallel data streams and transforming the signals from a frequency domain to a time domain;
the cyclic prefix inserting module is used for inserting a cyclic prefix into the data which passes through the inverse Fourier transform module;
the transmitting antenna is used for transmitting the analog signal;
the CDD-combined precoding codebook module is used for storing a precoding codebook comprising a plurality of codebooks and carrying out precoding operation on data by selecting an optimal codebook from the precoding codebook;
the starting updating signal sending module is used for sending a starting signal for updating the CDD delay value to each user equipment;
the feedback information receiving module is used for receiving the channel characteristic information sent by each user equipment.
Here, the probability analysis module is different from the corresponding module in the second embodiment in that: the probability analysis module in this embodiment is configured to perform probability analysis on the channel characteristics of each user respectively by using the channel characteristic information received by the feedback information receiving module, so as to select an optimal CDD delay value in the precoding codebook for each user, and send the optimal CDD delay value to the precoding codebook module combined with CDD, so as to update the CDD delay value in the precoding codebook.
In the system described in this embodiment, after the start update signal sending module in the base station sends the start signal for updating the CDD delay value to each user equipment, the start update signal receiving module in each user equipment receives the start signal and starts the channel characteristic determining module. At this time, the channel characteristic determining module determines the channel characteristic information of the user according to the channel estimation result output by the channel estimation submodule, and sends the obtained channel characteristic information to the feedback information receiving module in the base station, then, the feedback information receiving module sends the received channel characteristic information from each user equipment to the probability analysis module, the probability analysis module performs probability distribution analysis on the channel characteristic of each user equipment, and selects Nt (number of sending antennas) CDD delay values matched with the channel characteristic with the maximum probability for each user. Then, the probability analysis module sends the selected Nt CDD delay values to a pre-coding codebook module combined with CDD, and the CDD delay values in the pre-coding codebook are updated. Or the probability analysis module respectively carries out probability distribution analysis on the CDD delay values matched with the channel characteristics of each user device, selects Nt CDD delay values with the maximum probability for each user, and sends the Nt CDD delay values to the precoding codebook module combined with CDD to update the CDD delay values in the precoding codebook.
For the method described in the embodiment of fig. 9, it can also be implemented by using the system shown in fig. 7, please refer to the above description, in this embodiment, the function of the probability analysis module is different from that of the probability analysis module in the first embodiment, and the system is that the user equipment periodically and automatically starts the CDD delay value updating process in the precoding codebook (via the timing module).
Example five:
in this embodiment, a sending end, that is, a base station, determines whether to update a CDD delay value in a precoding codebook according to performance of a cell counted in a plurality of periods, and if not, keeps the CDD delay value in the precoding codebook unchanged; if the CDD delay value in the pre-coding code book is needed, the CDD delay value in the pre-coding code book is changed, self-adaptive updating of the CDD delay value in the pre-coding code book is achieved, and therefore system performance is guaranteed to the maximum extent. Referring to fig. 10, in a multi-user scheduling MIMO-OFDMA system formed by a base station and applying a precoding technique combined with CDD, the method according to the embodiment of the present invention includes the following steps:
according to different requirements, the cell performance can be average throughput, average error code performance, average delay performance, boundary user throughput and the like.
the updating method includes preferentially using the unused CDD delay value or preferentially using the CDD delay value having better performance for a past period of time, based on the record information of the base station. The updated CDD delay value may be sent to the terminal according to the system design requirements, or the terminal may not be notified.
Referring to fig. 11, the system for initiating the CDD delay value updating operation in the precoding codebook by the base station according to the embodiment of the present invention includes: and the transmitting end is the base station.
The base station includes: the system comprises a scheduling module, a demultiplexing module, a precoding module, a serial-parallel conversion module, an inverse Fourier transform module, a cyclic prefix insertion module, a transmitting antenna, a CDD-combined precoding codebook module, a CDD delay value updating module, a statistical result storage module and a cell performance statistical module.
The scheduling module is configured to perform scheduling of radio resources for multiple users according to feedback information (e.g., CQI) of the users, and allocate resources such as time, frequency, space, and code to different users;
the demultiplexing module is used for respectively sending the data streams to different antenna branches;
the precoding module is configured to perform precoding operation on the data stream, that is, perform weighting operation on data symbols of different antenna branches;
the serial-parallel conversion module is used for converting serial data streams into parallel data streams;
the inverse Fourier transform module is used for performing inverse Fourier transform on the parallel data streams and transforming the signals from a frequency domain to a time domain;
the cyclic prefix inserting module is used for inserting a cyclic prefix into the data which passes through the inverse Fourier transform module;
the transmitting antenna is used for transmitting the analog signal;
the CDD-combined precoding codebook module is used for storing a precoding codebook comprising a plurality of codebooks and carrying out precoding operation on data by selecting an optimal codebook from the precoding codebook;
the cell performance statistic module is used for periodically counting the cell performance and storing the cell performance and the corresponding CDD delay value into the statistic result storage module;
and the CDD delay value updating module is used for updating the CDD delay value in the precoding code book by using the result stored by the statistical result storage module.
The CDD delay value updating module selects an unused CDD delay value to update the CDD delay value in the precoding code book according to the recording information of the base station; or selecting a CDD delay value with better performance in a past period of time according to the record information of the base station to update the CDD delay value in the precoding code book.
Example six:
in this embodiment, a sending end, that is, a base station, determines whether to update a CDD delay value in a precoding codebook of a corresponding user according to performance of each user counted in a plurality of periods, and if not, keeps the CDD delay value in the precoding codebook of the user unchanged; if so, changing the CDD delay value in the user precoding codebook, and realizing that each user independently performs self-adaptive updating of the CDD delay value in the precoding codebook, thereby ensuring the system performance to the maximum extent. Referring to fig. 12, in a multi-user scheduling MIMO-OFDMA system formed by a base station and applying a precoding technique combined with CDD, the method according to the embodiment of the present invention includes the following steps:
according to different requirements, the user performance can be average throughput, average error code performance, average delay performance and the like.
the updating method includes preferentially using the unused CDD delay value or preferentially using the CDD delay value having better performance for a past period of time, based on the record information of the base station. The updated CDD delay value may be sent to the terminal according to the system design requirements, or the terminal may not be notified.
Referring to fig. 13, the system for initiating the CDD delay value updating operation in the precoding codebook by the base station according to the embodiment of the present invention includes: and the transmitting end is the base station.
The base station includes: the system comprises a scheduling module, a demultiplexing module, a precoding module, a serial-parallel conversion module, an inverse Fourier transform module, a cyclic prefix insertion module, a transmitting antenna, a CDD-combined precoding codebook module, a CDD delay value updating module, a statistical result storage module and a user performance statistical module.
The scheduling module is configured to perform scheduling of radio resources for multiple users according to feedback information (e.g., CQI) of the users, and allocate resources such as time, frequency, space, and code to different users;
the demultiplexing module is used for respectively sending the data streams to different antenna branches;
the precoding module is configured to perform precoding operation on the data stream, that is, perform weighting operation on data symbols of different antenna branches;
the serial-parallel conversion module is used for converting serial data streams into parallel data streams;
the inverse Fourier transform module is used for performing inverse Fourier transform on the parallel data streams and transforming the signals from a frequency domain to a time domain;
the cyclic prefix inserting module is used for inserting a cyclic prefix into the data which passes through the inverse Fourier transform module;
the transmitting antenna is used for transmitting the analog signal;
the CDD-combined precoding codebook module is used for storing a precoding codebook comprising a plurality of codebooks and carrying out precoding operation on data by selecting an optimal codebook from the precoding codebook;
the user performance statistic module is used for periodically counting the user performance and storing the user performance and the corresponding CDD delay value into the statistic result storage module;
and the CDD delay value updating module is used for updating the CDD delay value in the precoding code book of the corresponding user by using the result stored by the statistical result storage module.
The CDD delay value updating module selects an unused CDD delay value to update the CDD delay value in the precoding code book of the corresponding user according to the recording information of the base station; or according to the record information of the base station, selecting the CDD delay value with better performance in the past period of time to update the CDD delay value in the precoding code book of the corresponding user.
The method, system, base station and user equipment for determining a delay value for cyclic delay diversity according to the present invention are not limited to the applications listed in the description and the embodiments, but are fully applicable to various fields of application where the invention is applicable, and additional advantages and modifications will readily occur to those skilled in the art, and therefore the invention is not limited to the specific details, to the representative devices and to the illustrative examples shown and described herein, without departing from the spirit and scope of the general concept as defined by the appended claims and their equivalents.
Claims (73)
1. A method for determining delay values of Cyclic Delay Diversity (CDD) is used for a precoding system which comprises a base station and a plurality of user equipment and is combined with CDD, and the method is characterized by comprising the following steps:
a1, the user equipment respectively obtains the CDD delay value in the precoding code book which can obtain the optimal channel quality on each sub-band according to the channel estimation result, and feeds back the CDD delay value to the base station;
a2, the base station selects the CDD delay value in the global precoding codebook according to the CDD delay value in the received local optimal precoding codebook from each user equipment;
a3, the base station updates the CDD delay value in the precoding code book according to the selected CDD delay value in the global precoding code book.
2. The method of claim 1, wherein said step a1 is preceded by the further steps of:
the base station sends a starting signal to the user equipment, and starts the updating process of the CDD delay value in the precoding codebook, or the user equipment periodically and automatically starts the updating process of the CDD delay value in the precoding codebook.
3. The method as claimed in claim 1, wherein said step a1 further comprises the steps of:
the user equipment carries out channel estimation by using the pilot frequency information sent by the base station;
the user equipment respectively acquires the CDD delay value in the precoding codebook, which can obtain the maximum capacity, the maximum data rate or the minimum bit error rate, on each sub-band according to the channel estimation result;
and the user equipment sends the CDD delay value in the acquired local optimal precoding codebook to the base station.
4. The method of claim 1, wherein:
the user equipment respectively obtains the CDD delay value in the precoding code book which can obtain the optimal channel quality on each sub-band, and all possible CDD delay values are tested in a traversal mode one by one in a preset CDD delay value range on each sub-band to obtain the optimal CDD delay value which can enable the user to obtain the optimal channel quality.
5. The method of claim 1, wherein:
the user equipment respectively obtains the CDD delay value in the precoding code book which can obtain the optimal channel quality on each sub-band, and the optimal CDD delay value corresponding to the optimal channel quality which can be obtained on each sub-band by the user equipment is obtained through calculation.
6. The method as claimed in claim 1, wherein said step a2 further comprises the steps of:
the base station receives CDD delay values in the local optimal precoding code books from each user equipment and performs probability distribution analysis on the CDD delay values;
and the base station selects Nt CDD delay values with the maximum probability as CDD delay values in the global precoding code book, wherein Nt is the number of the transmitting antennas.
7. The method of claim 1, wherein:
the step A1 further comprises the steps of:
the user equipment respectively acquires a CDD delay value in a precoding code book capable of obtaining the optimal channel quality on each sub-band according to the channel estimation result, and feeds the optimal CDD delay value and the corresponding channel quality back to the base station;
the step A2 further comprises the steps of:
a base station receives CDD delay values and corresponding channel qualities in local optimal precoding code books from all user equipment, and performs probability distribution analysis on the channel qualities corresponding to the CDD delay values in the received precoding code books;
and the base station selects Nt CDD delay values with the maximum channel quality probability as the CDD delay values in the global precoding code book.
8. A system for determining a delay value of cyclic delay diversity comprises a base station and a plurality of user equipment; the base station includes: a precoding codebook module for storing a precoding codebook in combination with the CDD; the user equipment includes: a baseband demodulation module having a channel estimation sub-module; the method is characterized in that:
the user equipment further comprises:
a CDD delay value obtaining module in the local optimal precoding codebook, configured to obtain, on each subband, a CDD delay value in the local optimal precoding codebook that can obtain the optimal channel quality according to a channel estimation result output by the channel estimation submodule, and send the CDD delay value in the local optimal precoding codebook to the base station;
the base station further comprises:
the feedback information receiving module is used for receiving CDD delay values in the local optimal precoding code books sent by each user equipment;
and the probability analysis module is used for carrying out probability distribution analysis on CDD delay values in the local optimal precoding codebook of each user equipment, selecting Nt CDD delay values with the maximum probability as global CDD delay values in the precoding codebook, and sending the global CDD delay values to the CDD-combined precoding codebook module so as to update the CDD delay values in the precoding codebook.
9. The system of claim 8, wherein:
the CDD delay value obtaining module in the local optimal precoding codebook in the user equipment is further configured to obtain, on each sub-band, a CDD delay value in the local optimal precoding codebook that can obtain the optimal channel quality according to a channel estimation result output by the channel estimation submodule, and send the CDD delay value in the local optimal precoding codebook and the channel quality corresponding to the CDD delay value to the base station;
a feedback information receiving module in the base station, further configured to receive CDD delay values in the local optimal precoding codebook sent by each user equipment and channel qualities corresponding to the CDD delay values;
the probability analysis module in the base station is further configured to perform probability distribution analysis on channel quality corresponding to the CDD delay value in the local optimal precoding codebook of each user equipment, select Nt CDD delay values with the largest channel quality probability as CDD delay values in the global precoding codebook, and send the CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
10. The system of claim 8, wherein:
the base station further comprises: a starting update signal sending module, configured to send a starting signal for updating the CDD delay value to each user equipment;
the user equipment further comprises: and the starting updating signal receiving module is used for receiving the CDD delay value updating starting signal from the base station and starting the CDD delay value acquiring module in the local optimal precoding codebook.
11. The system of claim 8, wherein:
the user equipment further comprises: and the timing module is used for periodically generating and sending a CDD delay value starting updating signal to the CDD delay value acquisition module in the local optimal precoding codebook.
12. A base station comprising a combined CDD precoding codebook module for storing a precoding codebook; it is characterized by also comprising:
the feedback information receiving module is used for receiving CDD delay values in the local optimal precoding code books sent by each user equipment;
and the probability analysis module is used for carrying out probability distribution analysis on CDD delay values in the local optimal precoding codebook of each user equipment, selecting Nt CDD delay values with the maximum probability as global CDD delay values in the precoding codebook, and sending the global CDD delay values to the CDD-combined precoding codebook module so as to update the CDD delay values in the precoding codebook.
13. The base station of claim 12, wherein:
the feedback information receiving module is further configured to receive CDD delay values in the local optimal precoding codebook sent by each user equipment and channel quality corresponding to the CDD delay values;
the probability analysis module is further configured to perform probability distribution analysis on channel quality corresponding to the CDD delay value in the local optimal precoding codebook of each user equipment, select Nt CDD delay values with the largest channel quality probability as CDD delay values in the global precoding codebook, and send the CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
14. The base station of claim 12, further comprising:
and the starting updating signal sending module is used for sending a starting signal for updating the CDD delay value to each user equipment.
15. A user equipment comprising a baseband demodulation module having a channel estimation sub-module, further comprising:
and the CDD delay value acquisition module in the local optimal precoding codebook is used for respectively acquiring the CDD delay value in the local optimal precoding codebook capable of acquiring the optimal channel quality on each sub-band according to the channel estimation result output by the channel estimation submodule and transmitting the CDD delay value in the local optimal precoding codebook to the base station.
16. The user equipment of claim 15, wherein:
the CDD delay value obtaining module in the local optimal precoding codebook is further configured to obtain, on each sub-band, a CDD delay value in the local optimal precoding codebook that can obtain the optimal channel quality according to a channel estimation result output by the channel estimation sub-module, and send the CDD delay value in the local optimal precoding codebook and the channel quality corresponding to the CDD delay value to the base station.
17. The user equipment of claim 15, further comprising:
and the starting updating signal receiving module is used for receiving the CDD delay value updating starting signal from the base station and starting the CDD delay value acquiring module in the local optimal precoding codebook.
18. The user equipment of claim 15, further comprising:
and the timing module is used for periodically generating and sending a CDD delay value starting updating signal to the CDD delay value acquisition module in the local optimal precoding codebook.
19. A method for determining delay values of Cyclic Delay Diversity (CDD) is used for a precoding system which comprises a base station and a plurality of user equipment and is combined with CDD, and the method is characterized by comprising the following steps:
b1, the user equipment judges the channel characteristics according to the channel estimation result and feeds back the obtained channel characteristic information to the base station;
b2, the base station selects the CDD delay value in the global precoding code book according to the received channel characteristic information from each user equipment;
and B3, the base station updates the CDD delay value in the precoding code book according to the selected CDD delay value in the global precoding code book.
20. The method of claim 19, wherein said step B1 is preceded by the further step of:
the base station sends a starting signal to the user equipment, and starts the updating process of the CDD delay value in the precoding codebook, or the user equipment periodically and automatically starts the updating process of the CDD delay value in the precoding codebook.
21. The method of claim 19, wherein said step B2 further comprises the steps of:
the base station receives the channel characteristic information from each user equipment and carries out probability distribution analysis on the channel characteristic information;
and the base station selects Nt CDD delay values matched with the channel characteristics with the maximum probability as the CDD delay values in the global precoding code book.
22. The method of claim 19, wherein said step B2 further comprises the steps of:
the base station receives channel characteristic information from each user equipment and performs probability distribution analysis on CDD delay values matched with the channel characteristics;
and the base station selects Nt CDD delay values with the maximum probability as the CDD delay values in the global precoding code book.
23. The method according to claim 21 or 22, characterized in that:
the channel characteristics include: at least one of direct path/non-direct path, fast fading/slow fading, flat fading/frequency selective fading;
the matching principle is as follows:
the channel of the direct path corresponds to a CDD delay value in a larger pre-coding code book, and the channel of the indirect path corresponds to a CDD delay value in a smaller pre-coding code book;
the fast fading channel corresponds to a large CDD delay value in the pre-coding code book, and the slow fading channel corresponds to a small CDD delay value in the pre-coding code book;
the flat fading channel corresponds to the CDD delay value in the larger precoding codebook, and the frequency selective fading channel corresponds to the CDD delay value in the smaller precoding codebook.
24. A system for determining a delay value of cyclic delay diversity comprises a base station and a plurality of user equipment; the base station includes: a precoding codebook module for storing a precoding codebook in combination with the CDD; the user equipment includes: a baseband demodulation module having a channel estimation sub-module; the method is characterized in that:
the user equipment further comprises:
the channel characteristic judging module is used for judging channel characteristics according to a channel estimation result output by the channel estimation submodule and sending the obtained channel characteristic information to the base station;
the base station further comprises:
the feedback information receiving module is used for receiving the channel characteristic information sent by each user equipment;
and the probability analysis module is used for carrying out probability distribution analysis on the channel characteristics of each user equipment, selecting Nt CDD delay values matched with the channel characteristics with the maximum probability as global CDD delay values in the precoding codebook, and sending the CDD delay values to the precoding codebook module combined with CDD so as to update the CDD delay values in the precoding codebook.
25. The system of claim 24, wherein:
the probability analysis module in the base station is further configured to perform probability distribution analysis on the CDD delay values matched with the channel characteristics of each user equipment, select Nt CDD delay values with the largest probability as CDD delay values in the global precoding codebook, and send the CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
26. The system of claim 24, wherein:
the base station further comprises: a starting update signal sending module, configured to send a starting signal for updating the CDD delay value to each user equipment;
the user equipment further comprises: and the starting updating signal receiving module is used for receiving the CDD delay value updating starting signal from the base station and starting the channel characteristic judging module.
27. The system of claim 24, wherein:
the user equipment further comprises: and the timing module is used for periodically generating and sending a CDD delay value start updating signal to the channel characteristic judging module.
28. A base station comprising a combined CDD precoding codebook module for storing a precoding codebook; it is characterized by also comprising:
the feedback information receiving module is used for receiving the channel characteristic information sent by each user equipment;
and the probability analysis module is used for carrying out probability distribution analysis on the channel characteristics of each user equipment, selecting Nt CDD delay values matched with the channel characteristics with the maximum probability as global CDD delay values in the precoding codebook, and sending the CDD delay values to the precoding codebook module combined with CDD so as to update the CDD delay values in the precoding codebook.
29. The base station of claim 28, wherein:
the probability analysis module is further configured to perform probability distribution analysis on the CDD delay values matched with the channel characteristics of each user equipment, select Nt CDD delay values with the highest probability as CDD delay values in the global precoding codebook, and send the CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
30. The base station of claim 28, further comprising:
and the starting updating signal sending module is used for sending a starting signal for updating the CDD delay value to each user equipment.
31. A user equipment comprising a baseband demodulation module having a channel estimation sub-module, further comprising:
and the channel characteristic judging module is used for judging the channel characteristics according to the channel estimation result output by the channel estimation submodule and sending the obtained channel characteristic information to the base station.
32. The user equipment of claim 31, further comprising:
and the starting updating signal receiving module is used for receiving the CDD delay value updating starting signal from the base station and starting the channel characteristic judging module.
33. The user equipment of claim 31, further comprising:
and the timing module is used for periodically generating and sending a CDD delay value start updating signal to the channel characteristic judging module.
34. A method for determining delay values of Cyclic Delay Diversity (CDD) is used for a precoding system which comprises a base station and a plurality of user equipment and is combined with CDD, and the method is characterized by comprising the following steps:
c1, the user equipment respectively obtains the CDD delay value in the precoding code book which can obtain the optimal channel quality on each sub-band according to the channel estimation result, and feeds the CDD delay value back to the base station;
c2, the base station selects the CDD delay value in the optimal precoding code book for each user respectively according to the CDD delay value in the received local optimal precoding code book from each user equipment;
and C3, the base station updates the CDD delay value in the precoding code book according to the CDD delay value in the selected precoding code book.
35. The method of claim 34, wherein said step C1 is preceded by the step of:
the base station sends a starting signal to the user equipment, and starts the updating process of the CDD delay value in the precoding codebook, or the user equipment periodically and automatically starts the updating process of the CDD delay value in the precoding codebook.
36. The method as claimed in claim 34, wherein said step C1 further comprises the steps of:
the user equipment carries out channel estimation by using the pilot frequency information sent by the base station;
the user equipment respectively acquires the CDD delay value in the precoding codebook, which can obtain the maximum capacity, the maximum data rate or the minimum bit error rate, on each sub-band according to the channel estimation result;
and the user equipment sends the CDD delay value in the acquired local optimal precoding codebook to the base station.
37. The method of claim 34, wherein:
the user equipment respectively obtains the CDD delay value in the precoding code book which can obtain the optimal channel quality on each sub-band, and all possible CDD delay values are tested in a traversal mode one by one in a preset CDD delay value range on each sub-band to obtain the optimal CDD delay value which can enable the user to obtain the optimal channel quality.
38. The method of claim 34, wherein:
the user equipment respectively obtains the CDD delay value in the precoding code book which can obtain the optimal channel quality on each sub-band, and the optimal CDD delay value corresponding to the optimal channel quality which can be obtained on each sub-band by the user equipment is obtained through calculation.
39. The method as claimed in claim 34, wherein said step C2 further comprises the steps of:
the base station receives CDD delay values in the local optimal precoding code books from the user equipment, and carries out probability distribution analysis on the CDD delay values in the local optimal precoding code books of the user equipment;
and the base station selects Nt CDD delay values with the maximum probability as the CDD delay values in the optimal precoding code book of the corresponding user.
40. The method of claim 34, wherein:
the step C1 further includes the steps of:
the user equipment respectively acquires a CDD delay value in a precoding code book capable of obtaining the optimal channel quality on each sub-band according to the channel estimation result, and feeds the optimal CDD delay value and the corresponding channel quality back to the base station;
the step C2 further includes the steps of:
the base station receives CDD delay values and corresponding channel qualities in the local optimal precoding code books from the user equipment, and carries out probability distribution analysis on the channel qualities corresponding to the optimal CDD delay values of the user equipment;
and the base station selects Nt CDD delay values with the maximum channel quality probability as the CDD delay values in the optimal precoding code book of the corresponding user.
41. A system for determining a delay value of cyclic delay diversity comprises a base station and a plurality of user equipment; the base station includes: a precoding codebook module for storing a precoding codebook in combination with the CDD; the user equipment includes: a baseband demodulation module having a channel estimation sub-module; the method is characterized in that:
the user equipment further comprises:
a CDD delay value obtaining module in the local optimal precoding codebook, configured to obtain, on each subband, a CDD delay value in the local optimal precoding codebook that can obtain the optimal channel quality according to a channel estimation result output by the channel estimation submodule, and send the CDD delay value in the local optimal precoding codebook to the base station;
the base station further comprises:
the feedback information receiving module is used for receiving CDD delay values in the local optimal precoding code books sent by each user equipment;
and the probability analysis module is used for respectively carrying out probability distribution analysis on the CDD delay values in the local optimal precoding codebook of each user equipment, selecting Nt CDD delay values with the maximum probability as the CDD delay values in the optimal precoding codebook of the corresponding user, and sending the CDD delay values to the CDD-combined precoding codebook module so as to update the CDD delay values in the precoding codebook.
42. The system of claim 41, wherein:
the CDD delay value obtaining module in the local optimal precoding codebook in the user equipment is further configured to obtain, on each sub-band, a CDD delay value in the local optimal precoding codebook that can obtain the optimal channel quality according to a channel estimation result output by the channel estimation submodule, and send the CDD delay value in the local optimal precoding codebook and the channel quality corresponding to the CDD delay value to the base station;
a feedback information receiving module in the base station, further configured to receive CDD delay values in the local optimal precoding codebook sent by each user equipment and channel qualities corresponding to the CDD delay values;
the probability analysis module in the base station is further configured to perform probability distribution analysis on the channel quality corresponding to the optimal CDD delay value of each user equipment, select Nt CDD delay values with the largest channel quality probability as the optimal CDD delay values in the precoding codebook of the corresponding user, and send the CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
43. The system of claim 41, wherein:
the base station further comprises: a starting update signal sending module, configured to send a starting signal for updating the CDD delay value to each user equipment;
the user equipment further comprises: and the starting updating signal receiving module is used for receiving the CDD delay value updating starting signal from the base station and starting the CDD delay value acquiring module in the local optimal precoding codebook.
44. The system of claim 41, wherein:
the user equipment further comprises: and the timing module is used for periodically generating and sending a CDD delay value starting updating signal to the CDD delay value acquisition module in the local optimal precoding codebook.
45. A base station comprising a combined CDD precoding codebook module for storing a precoding codebook; it is characterized by also comprising:
the feedback information receiving module is used for receiving CDD delay values in the local optimal precoding code books sent by each user equipment;
and the probability analysis module is used for respectively carrying out probability distribution analysis on the CDD delay values in the local optimal precoding codebook of each user equipment, selecting Nt CDD delay values with the maximum probability as the CDD delay values in the optimal precoding codebook of the corresponding user, and sending the CDD delay values to the CDD-combined precoding codebook module so as to update the CDD delay values in the precoding codebook.
46. The base station of claim 45, wherein:
the feedback information receiving module is further configured to receive CDD delay values in the local optimal precoding codebook sent by each user equipment and channel quality corresponding to the CDD delay values;
the probability analysis module is further configured to perform probability distribution analysis on channel quality corresponding to the optimal CDD delay value of each user equipment, select Nt CDD delay values with the largest channel quality probability as the optimal CDD delay values in the precoding codebook of the corresponding user, and send the CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
47. The base station of claim 45, further comprising:
and the starting updating signal sending module is used for sending a starting signal for updating the CDD delay value to each user equipment.
48. A method for determining delay values of Cyclic Delay Diversity (CDD) is used for a precoding system which comprises a base station and a plurality of user equipment and is combined with CDD, and the method is characterized by comprising the following steps:
d1, the user equipment judges the channel characteristics according to the channel estimation result and feeds back the obtained channel characteristic information to the base station;
d2, the base station selects the optimal CDD delay value in the precoding code book for each user respectively according to the received channel characteristic information from each user equipment;
d3, the base station updates the CDD delay value in the precoding code book according to the CDD delay value in the selected precoding code book.
49. The method according to claim 48, wherein said step D1 is preceded by the further step of:
the base station sends a starting signal to the user equipment, and starts the updating process of the CDD delay value in the precoding codebook, or the user equipment periodically and automatically starts the updating process of the CDD delay value in the precoding codebook.
50. The method according to claim 48, wherein said step D2 further comprises the steps of:
the base station receives channel characteristic information from each user equipment and carries out probability distribution analysis on the channel characteristics of each user respectively;
and the base station selects Nt CDD delay values matched with the channel characteristics with the maximum probability as the CDD delay values in the optimal precoding code book of the corresponding user.
51. The method according to claim 48, wherein said step D2 further comprises the steps of:
the base station receives channel characteristic information from each user device, and respectively performs probability distribution analysis on CDD delay values matched with the channel characteristics of each user;
and the base station selects Nt CDD delay values with the maximum probability as the CDD delay values in the optimal precoding code book of the corresponding user.
52. The method of claim 50 or 51, wherein:
the channel characteristics include: at least one of direct path/non-direct path, fast fading/slow fading, flat fading/frequency selective fading;
the matching principle is as follows:
the channel of the direct path corresponds to a CDD delay value in a larger pre-coding code book, and the channel of the indirect path corresponds to a CDD delay value in a smaller pre-coding code book;
the fast fading channel corresponds to a large CDD delay value in the pre-coding code book, and the slow fading channel corresponds to a small CDD delay value in the pre-coding code book;
the flat fading channel corresponds to the CDD delay value in the larger precoding codebook, and the frequency selective fading channel corresponds to the CDD delay value in the smaller precoding codebook.
53. A system for determining a delay value of cyclic delay diversity comprises a base station and a plurality of user equipment; the base station includes: a precoding codebook module for storing a precoding codebook in combination with the CDD; the user equipment includes: a baseband demodulation module having a channel estimation sub-module; the method is characterized in that:
the user equipment further comprises:
the channel characteristic judging module is used for judging channel characteristics according to a channel estimation result output by the channel estimation submodule and sending the obtained channel characteristic information to the base station;
the base station further comprises:
the feedback information receiving module is used for receiving the channel characteristic information sent by each user equipment;
and the probability analysis module is used for respectively carrying out probability distribution analysis on the channel characteristics of each user equipment, selecting Nt CDD delay values matched with the channel characteristics with the maximum probability as the CDD delay values in the optimal precoding codebook of the corresponding user, and sending the CDD delay values to the precoding codebook module combined with CDD so as to update the CDD delay values in the precoding codebook.
54. The system of claim 53, wherein:
the probability analysis module in the base station is further configured to perform probability distribution analysis on the CDD delay values matched with the channel characteristics of each user equipment, select Nt CDD delay values with the largest probability as the CDD delay values in the optimal precoding codebook of the corresponding user, and send the CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
55. The system of claim 53, wherein:
the base station further comprises: a starting update signal sending module, configured to send a starting signal for updating the CDD delay value to each user equipment;
the user equipment further comprises: and the starting updating signal receiving module is used for receiving the CDD delay value updating starting signal from the base station and starting the channel characteristic judging module.
56. The system of claim 53, wherein:
the user equipment further comprises: and the timing module is used for periodically generating and sending a CDD delay value start updating signal to the channel characteristic judging module.
57. A base station comprising a combined CDD precoding codebook module for storing a precoding codebook; it is characterized by also comprising:
the feedback information receiving module is used for receiving the channel characteristic information sent by each user equipment;
and the probability analysis module is used for respectively carrying out probability distribution analysis on the channel characteristics of each user equipment, selecting Nt CDD delay values matched with the channel characteristics with the maximum probability as the CDD delay values in the optimal precoding codebook of the corresponding user, and sending the CDD delay values to the precoding codebook module combined with CDD so as to update the CDD delay values in the precoding codebook.
58. The base station of claim 57, wherein:
the probability analysis module is further configured to perform probability distribution analysis on the CDD delay values matched with the channel characteristics of each user equipment, select Nt CDD delay values with the highest probability as the optimal CDD delay values in the precoding codebook of the corresponding user, and send the CDD delay values to the CDD-combined precoding codebook module to update the CDD delay values in the precoding codebook.
59. The base station of claim 57, further comprising:
and the starting updating signal sending module is used for sending a starting signal for updating the CDD delay value to each user equipment.
60. A method for determining delay values of Cyclic Delay Diversity (CDD) is used for a precoding system which comprises a base station and a plurality of user equipment and is combined with CDD, and the method is characterized by comprising the following steps:
e1, periodically counting the cell performance of the base station;
e2, in each statistical period, the base station records the cell performance and the corresponding CDD delay value;
e3, the base station judges whether the cell performance is reduced according to the recorded cell performance of a plurality of periods, and when the cell performance is determined to be reduced, the CDD delay value in the precoding code book is updated.
61. The method of claim 60, wherein:
the cell performance is at least one of average throughput, average error code performance, average time delay performance and boundary user throughput.
62. The method of claim 60, wherein:
in step E3, the CDD delay value in the updated precoding codebook is: according to the record information of the base station, the unused CDD delay value is selected to be updated.
63. The method of claim 60, wherein:
in step E3, the CDD delay value in the updated precoding codebook is: according to the record information of the base station, the CDD delay value with better performance in a past period is selected for updating.
64. A base station comprising a combined CDD precoding codebook module for storing a precoding codebook; the method is characterized in that:
the system also comprises a CDD delay value updating module, a statistical result storage module and a cell performance statistical module;
the cell performance statistic module is used for periodically counting the cell performance and storing the cell performance and the corresponding CDD delay value into the statistic result storage module;
and the CDD delay value updating module is used for updating the CDD delay value in the precoding code book by using the result stored by the statistical result storage module.
65. The base station of claim 64, wherein:
the CDD delay value updating module is further configured to select an unused CDD delay value to update the CDD delay value in the precoding codebook according to the recording information of the base station.
66. The base station of claim 64, wherein:
the CDD delay value updating module is further configured to select a CDD delay value with better performance in a past period of time according to the recording information of the base station to update the CDD delay value in the precoding codebook.
67. A method for determining delay values of Cyclic Delay Diversity (CDD) is used for a precoding system which comprises a base station and a plurality of user equipment and is combined with CDD, and the method is characterized by comprising the following steps:
f1, the base station periodically counts the user performance;
f2, in each statistical period, the base station records the user performance and the corresponding CDD delay value;
f3, the base station judges whether the user performance is reduced according to the recorded cell performance of a plurality of periods, and when the user performance is determined to be reduced, the CDD delay value in the precoding code book of the corresponding user is updated.
68. The method of claim 67, wherein:
the user performance is at least one of average throughput, average error code performance and average time delay performance.
69. The method of claim 67, wherein:
in step F3, the updating CDD delay values in the precoding code books of the corresponding users is: according to the record information of the base station, the unused CDD delay value is selected to be updated.
70. The method of claim 67, wherein:
in step F3, the updating CDD delay values in the precoding code books of the corresponding users is: according to the record information of the base station, the CDD delay value with better performance in a past period is selected for updating.
71. A base station comprising a combined CDD precoding codebook module for storing a precoding codebook; the method is characterized in that:
the system also comprises a CDD delay value updating module, a statistical result storage module and a user performance statistical module;
the user performance statistic module is used for periodically counting the user performance and storing the user performance and the corresponding CDD delay value into the statistic result storage module;
and the CDD delay value updating module is used for updating the CDD delay value in the precoding code book of the corresponding user by using the result stored by the statistical result storage module.
72. The base station of claim 71, wherein:
the CDD delay value updating module is further configured to select an unused CDD delay value to update the CDD delay value in the precoding codebook of the corresponding user according to the recording information of the base station.
73. The base station of claim 71, wherein:
the CDD delay value updating module is further configured to select a CDD delay value with better performance in a past period of time according to the recording information of the base station to update the CDD delay value in the precoding codebook of the corresponding user.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2007101089991A CN101359944A (en) | 2006-10-31 | 2007-06-11 | Method, system, base station and user equipment determining cyclic delay and diversity delay |
| US11/932,271 US20080132282A1 (en) | 2006-10-31 | 2007-10-31 | Method, system, base station, and user equipment for determining delay value of cyclic delay diversity |
| EP07021295.6A EP1919115A3 (en) | 2006-10-31 | 2007-10-31 | Method, system, base station and user equipment for determining delay value of cyclic delay diversity |
| JP2007283977A JP2008118650A (en) | 2006-10-31 | 2007-10-31 | Method, system, base station and ue for determining delay value of cyclic delay diversity |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200610143109 | 2006-10-31 | ||
| CN200610143109.6 | 2006-10-31 | ||
| CNA2007101089991A CN101359944A (en) | 2006-10-31 | 2007-06-11 | Method, system, base station and user equipment determining cyclic delay and diversity delay |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102484516A (en) * | 2009-06-24 | 2012-05-30 | 株式会社泛泰 | Method for compensating for frequency fading using adaptive cyclic delay diversity, and transmitting apparatus and method and receiving apparatus and method using the same |
| CN103716263B (en) * | 2013-12-18 | 2016-08-31 | 东南大学 | Based on the parallel efficient pilot frequency system offset in large-scale multi-antenna system |
| US20220190892A1 (en) * | 2019-04-05 | 2022-06-16 | Lg Electronics Inc. | Method for transmitting and receiving signal in wireless communication system, and apparatus therefor |
| CN115314407A (en) * | 2022-08-03 | 2022-11-08 | 东南大学 | Network flow based online game QoE detection method |
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- 2007-06-11 CN CNA2007101089991A patent/CN101359944A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102484516A (en) * | 2009-06-24 | 2012-05-30 | 株式会社泛泰 | Method for compensating for frequency fading using adaptive cyclic delay diversity, and transmitting apparatus and method and receiving apparatus and method using the same |
| CN103716263B (en) * | 2013-12-18 | 2016-08-31 | 东南大学 | Based on the parallel efficient pilot frequency system offset in large-scale multi-antenna system |
| US20220190892A1 (en) * | 2019-04-05 | 2022-06-16 | Lg Electronics Inc. | Method for transmitting and receiving signal in wireless communication system, and apparatus therefor |
| US11881915B2 (en) * | 2019-04-05 | 2024-01-23 | Lg Electronics Inc. | Method for transmitting and receiving signal in wireless communication system, and apparatus therefor |
| CN115314407A (en) * | 2022-08-03 | 2022-11-08 | 东南大学 | Network flow based online game QoE detection method |
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