CN103326742B - Multi-path tracking method and device - Google Patents
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Abstract
The invention discloses a multi-path tracking method and device. The method comprises the steps of searching the positions of multiple paths and expanding a certain number of paths in front of and behind the positions of the multiple paths, acquiring the signal to interference ratio of each expanded path and selecting paths needing to be combined according to the signal to interference ratio of each path, carrying out maximal-ratio combining on the symbol level data of the selected paths needing to be combined, and taking the positions of the selected paths needing to be combined as the multi-path tracking positions. According to the multi-path tracking method and device, the problem that multiple path position searching carried out according to correlation technique is high in error is solved, multiple path position searching accuracy is higher, the block error rate of large transmission blocks is reduced, the peak rate of uplink transmission is increased, and extra gain of multiple path combination is obtained.
Description
Technical Field
The present invention relates to the field of communications, and in particular, to a method and an apparatus for multipath tracking.
Background
In code division multiple access systems, Rake receivers are widely used. The multipath searcher, which is an important component of the Rake receiver, is responsible for the searching and assignment of the multipath. After the Rake receiver searches the multipath, the searched multipath is descrambled and despread, and finally the multipath is combined in a maximum ratio. Whether the positions of the searched multipaths accurately determine the performance of the receiver. With further increase of data transmission rate, higher requirements are put on the precision of the searcher. When the transmission block is large, the multipath position is deviated from the 1/8 chip distance only to cause the block error rate of the received data to reach 100%.
In the related art, a multipath position is generally searched by means of matched filtering, and the searching precision is 1/2 chips. Furthermore, the movement of the mobile station at the true multipath position within the update period of the searcher due to clock problems such as a crystal oscillator inevitably occurs, and the movement of the mobile station also causes the jitter of the multipath position. However, because the error of multipath search and the fast jitter of multipath position can cause the deviation of multipath position, in practical application, the requirement for the accuracy of multipath search is higher, and the movement of multipath position caused by the clock problem of crystal oscillator and the like and the jitter of multipath position caused by the movement of mobile station are both unavoidable.
Aiming at the problem of high multipath position error searched in the related technology, no effective solution is provided at present.
Disclosure of Invention
The invention provides a multipath tracking method and a multipath tracking device aiming at the problem of higher multipath position error searched in the related technology, so as to at least solve the problem.
According to an aspect of the present invention, there is provided a method of multipath tracking, the method comprising: searching the positions of the multipath, and expanding the multipath with the specified number before and after the searched positions of the multipath; acquiring the signal-to-interference ratio of each expanded multipath, and selecting the multipath to be combined according to the signal-to-interference ratio of each multipath; and taking the position of the selected multipath needing to be combined as the position of multipath tracking.
Before obtaining the signal-to-interference ratio value of each multipath, the method comprises the following steps: performing descrambling operation and despreading operation on each multipath after spreading to acquire symbol-level data of a control channel of each multipath; acquiring the signal-to-interference ratio value of each multipath comprises the following steps: and calculating the signal-to-interference ratio of each multipath according to the symbol-level data of the control channel of each multipath.
Selecting the multipath to be combined according to the signal-to-interference ratio of each multipath comprises: taking the multipath with the maximum signal-to-interference ratio value in the set number as the multipath to be combined; or, judging whether the multipath searched before expansion is located on the sampling point of the searcher, if so, taking the multipath located on the sampling point and several pairs of multipath symmetrically located at two sides of the multipath as the multipath to be combined; if not, the multipath with the maximum signal-to-interference ratio value and the set number is taken as the multipath to be combined.
After the selected position of the multipath to be combined is taken as the position of multipath tracking, the method further comprises: carrying out maximum ratio combination on the selected multipath symbol-level data needing to be combined; and carrying out demodulation operation and decoding operation on the combined symbol-level data to obtain information bits.
When obtaining the symbol-level data of the control channel of each multipath, the method further includes: obtaining symbol-level data of each multipath data channel; after obtaining the signal-to-interference ratio value of each multipath, the method further comprises: calculating the combining weight of each multipath according to the symbol level data of the control channel of each multipath; the maximum ratio combining of the selected multipath symbol level data to be combined comprises the following steps: and carrying out maximum ratio combination on the symbol-level data of the multipath data channel to be combined according to the combining weight of the multipath to be combined.
According to another aspect of the present invention, there is provided an apparatus for multipath tracking, the apparatus comprising: the expansion module is used for searching the positions of the multipath and expanding the multipath with the specified number before and after the searched positions of the multipath; a signal-to-interference ratio obtaining module, configured to obtain a signal-to-interference ratio of each multipath after being expanded by the expanding module; a multipath selection module, configured to select a multipath to be combined according to the signal-to-interference ratio of each multipath obtained by the signal-to-interference ratio obtaining module; and the position tracking module is used for taking the selected positions of the multipaths needing to be combined as the positions of multipath tracking.
The above-mentioned device still includes: a symbol level data acquisition module, configured to perform descrambling and despreading operations on each multipath after spreading, and acquire symbol level data of a control channel of each multipath; the signal-to-interference ratio acquisition module comprises: and the signal-to-interference ratio calculating unit is used for calculating the signal-to-interference ratio of each multipath according to the symbol level data of the control channel of each multipath acquired by the symbol level data acquiring module.
The multipath selection module comprises: the first selection unit is used for taking the multipath with the maximum signal-to-interference ratio value and the set number as the multipath needing to be combined; or, the second selection unit, is used for judging whether the multipath searched before expanding is located on the sampling point of the searcher, if yes, regard multipath located on above-mentioned sampling point and several pairs of multipaths located bilaterally symmetrically of the above-mentioned multipath as the multipath needing to be merged; if not, the multipath with the maximum signal-to-interference ratio value and the set number is taken as the multipath to be combined.
The above-mentioned device still includes: a maximum ratio combining module, configured to perform maximum ratio combining on the multipath symbol-level data that needs to be combined and is selected by the multipath selection module; and the information bit acquisition module is used for demodulating and decoding the combined symbol-level data to obtain information bits.
The symbol level data obtaining module is further configured to obtain symbol level data of each multipath data channel; the above-mentioned device still includes: a combining weight calculating module, configured to calculate a combining weight of each multipath according to the symbol-level data of the control channel of each multipath; the maximum ratio combining module includes: and the maximum ratio combining unit is used for carrying out maximum ratio combining on the symbol-level data of the multipath data channel needing to be combined according to the combining weight of the multipath needing to be combined.
According to the invention, after the positions of the multipaths are searched, a specified number of multipaths are expanded in front of and behind the positions, then the signal-to-interference ratio of each expanded multipath is obtained, the multipath to be combined is selected according to the signal-to-interference ratio of each multipath, and finally the position of the selected multipath to be combined is used as the position of multipath tracking, so that the problem of higher error of the multipath positions searched in the related technology is solved, the searching precision of the multipath positions is higher, the block error rate of a large transmission block is reduced, the peak rate of uplink transmission is improved, and the extra gain of the combined multipath is obtained.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
FIG. 1 is a flow diagram of a method of multipath tracking according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of multipath propagation according to an embodiment of the present invention;
FIG. 3 is a flow diagram of a multipath spreading process according to an embodiment of the present invention;
fig. 4 is a flow diagram of a multipath spreading, combining process according to an embodiment of the present invention;
FIG. 5 is a first schematic diagram of a multipath spreading strategy according to an embodiment of the present invention;
FIG. 6 is a second schematic diagram of a multipath selection strategy in accordance with an embodiment of the present invention;
FIG. 7 is a third schematic diagram of a multipath selection strategy in accordance with an embodiment of the present invention;
FIG. 8 is a fourth illustration of a multipath selection strategy according to an embodiment of the present invention;
fig. 9 is a fifth illustration of a multipath selection strategy in accordance with an embodiment of the present invention;
fig. 10 is a sixth schematic diagram of a multipath selection strategy in accordance with an embodiment of the present invention;
fig. 11 is a seventh illustration of a multipath selection strategy in accordance with an embodiment of the present invention;
fig. 12 is an eighth schematic diagram of a multipath selection strategy in accordance with an embodiment of the present invention;
fig. 13 is a ninth illustration of a multipath selection strategy in accordance with an embodiment of the present invention;
fig. 14 is a tenth schematic diagram of a multipath selection strategy in accordance with an embodiment of the present invention;
fig. 15 is a block diagram of a multipath tracking apparatus according to an embodiment of the present invention;
fig. 16 is a detailed structural block diagram of a multipath tracking apparatus according to an embodiment of the present invention;
fig. 17 is another block diagram of the multipath spreading and combining apparatus according to the embodiment of the present invention.
Detailed Description
The invention will be described in detail hereinafter with reference to the accompanying drawings in conjunction with embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
In the related art, a multipath search is generally performed by using a matched filtering method, a descrambling operation and a despreading operation are performed on searched multipaths, and then maximum ratio combining of the multipaths is performed. The following examples are given for the purpose of illustration.
The present embodiment provides a method for multipath combining, which may be implemented on a device (e.g., a receiver), such as the method flowchart for multipath combining shown in fig. 1, and the method includes the following steps (step S102-step S106):
step S102, the device searches the positions of the multipath and expands the multipath with the designated quantity before and after the searched positions of the multipath;
step S104, the device obtains the signal-to-interference ratio of each expanded multipath, and selects the multipath to be combined according to the signal-to-interference ratio of each multipath;
in step S106, the device uses the selected position of the multipath to be combined as the position of multipath tracking.
By the method, after the positions of the multipaths are searched, a specified number of multipaths are expanded in front of and behind the positions, then the signal-to-interference ratio of each expanded multipath is obtained, the multipath to be combined is selected according to the signal-to-interference ratio of each multipath, and finally the selected position of the multipath to be combined is used as the position of multipath tracking, so that the problem that the position error of the multipath searched in the related technology is high is solved, the searching precision of the multipath position is high, the block error rate of a large transmission block is reduced, the peak rate of uplink transmission is improved, and the extra gain of the combined multipath is obtained.
In step S102, the device searches for the positions of the multipaths, and then expands a specified number of multipaths before and after the positions of the searched multipaths, as shown in the multipath expansion diagram of fig. 2, the middle solid line of fig. 2 refers to the positions of the searched multipaths, the several dotted lines beside the solid line are the expanded multipaths, the number of the expanded multipaths may be one or more, and the number of the expanded multipaths may be set according to actual conditions.
After a specified number of multipaths are expanded before and after the positions of the searched multipaths, the device needs to obtain a Signal to Interference power ratio (SIR for short, hereinafter referred to as Signal to Interference ratio) of each multipath, the Signal to Interference ratio needs to be calculated according to symbol-level data of a control channel of each multipath, and since the spreading gain of the control channel is large and the calculation of the Signal to Interference ratio value of each multipath is performed on the basis of a certain time average, the Signal to Interference ratio is less affected by noise, and the accurate positions of the multipaths can be basically reflected. Therefore, this embodiment provides a preferred embodiment, that is, before acquiring the signal-to-interference ratio value of each multipath, performing a descrambling operation and a despreading operation on each multipath after spreading to acquire the symbol-level data of the control channel of each multipath, and then the process of acquiring the signal-to-interference ratio value of each multipath in step S104 may include: and calculating the signal-to-interference ratio of each multipath according to the symbol-level data of the control channel of each multipath. The acquisition mode of the signal-to-interference ratio is simple and easy to realize, and provides a basis for selecting the multipath to be combined according to the signal-to-interference ratio subsequently.
The first mode is as follows: the device takes the multipath with the maximum signal-to-interference ratio value in the set number as the multipath to be combined; the second way is: the equipment judges whether the multipath searched before expansion is positioned on a sampling point of the searcher, if so, the multipath positioned on the sampling point and a plurality of pairs of multipath positioned at two sides of the multipath are taken as the multipath to be combined, for example, the multipath on the sampling point and 1 or two pairs of multipath at two sides of the sampling point can be combined according to symmetry, and then the remaining multipath can be selectively combined according to the size of the signal-to-interference ratio; and if not, taking the multipath with the maximum signal-to-interference ratio value with the set number as the multipath to be combined. For example, two paths around the sampling point may be combined first, and then the remaining paths may be selectively combined according to the signal-to-interference ratio. The two selection modes are fast and reasonable, and provide a basis for carrying out maximum ratio combination on the selected multipath symbol-level data needing to be combined subsequently. Of course, the selection of the multipath to be combined is not limited to the above two ways, as long as the appropriate multipath to be combined can be selected.
After selecting suitable multipath to be combined, the device needs to perform maximum ratio combining operation according to the combining weight of the multipath, and therefore, the device needs to calculate the combining weight of each multipath according to the symbol-level data of the control channel of each multipath. In the operation process of maximum ratio combining, the device performs maximum ratio combining on the symbol-level data of the multipath data channels to be combined, and therefore when the device acquires the symbol-level data of the control channel of each multipath, it also needs to acquire the symbol-level data of the data channel of each multipath. Thus, the above-mentioned acquisition process of the data channel provides a basis for the subsequent maximum ratio combining.
After the device performs maximum ratio combining on the selected multipath symbol-level data to be combined, the device also needs to perform demodulation operation and decoding operation on the combined symbol-level data to obtain information bits. The multipath searcher in the correlation technique mostly adopts the chip-level pilot sequence autocorrelation to obtain the multipath position, so that the multipath selection mode based on the signal-to-interference ratio of the multipath symbol-level data after descrambling and despreading provided by the embodiment is more accurate than the autocorrelation mode, and after maximum ratio combination of each multipath descrambled and despread symbol-level data, the information bit sent by the sending end is obtained through hard decision or decoding, so that the signal-to-interference ratio of the multipath directly reflects the signal quality, and the error rate after maximum ratio combination is reduced by the mode.
Fig. 3 is a flowchart of a multipath spreading process according to an embodiment of the present invention, and as shown in fig. 3, the process includes the following steps (step S302-step S316):
step S302, multipath search is carried out according to the autocorrelation of the pilot frequency sequence. When multipath spreading is combined with advanced receivers, the effect of the spread false path on the advanced receiver must be eliminated, and the advanced receiver combines the searched energy paths and also combines noise paths for interference cancellation among the multiple paths. Therefore, the influence of the extended pseudo path on the noise path must be excluded.
Step S304, judging whether the multipath expansion is enabled, if so, indicating that the interface flag position is 1, executing step S306, if not, indicating that the interface flag position is 0, and executing step S314.
In step S306, information of the positions of the searched multipaths (which may also be referred to as original paths, that is, the original paths are the multipaths searched by the multipath searcher) is retained, where the information includes delay, energy, antenna number, new and old path states, and the like.
Step S308, expanding the multiple paths, where each original path can expand N multiple paths, where N is a configuration item, for example, N can be configured to be 4, and each original path can expand at most four multiple paths.
Step S310, configuring parameters of the extended multipath, where the parameters include energy, antenna number, and the like.
In step S312, the search for the noise path is closed.
In step S314, a noise path is searched for, and then step S316 is executed.
In step S316, the multipath spreading ends.
Fig. 4 is a flowchart of a multipath spreading, combining process according to an embodiment of the present invention, as shown in fig. 4, the process includes the following steps (step S402-step S416):
step S402, performing matched filtering on the antenna data, i.e. autocorrelation of the pilot sequence. Since the pilot sequence exists in each time slot, in order to resist noise, the pilot sequences of a plurality of time slots can be subjected to autocorrelation to find out the autocorrelation peak, i.e. the position of multipath.
In step S404, a specified number of multipaths are spread before and after the searched multipath positions, for example, four paths are spread at positions of ± 1/4, ± 1/8 chips.
Step S406, descrambling and despreading the control channel and the data channel for each multipath, and obtaining symbol-level data of the control channel and the data channel.
Step S408, the symbol-level data of the control channel is processed to obtain the signal-to-interference ratio of each multipath.
Step S410, the symbol-level data of the control channel is processed to obtain the combining weight of each multipath.
Step S412, selecting the multipath to be combined according to the signal-to-interference ratio of each multipath.
The simple path selection strategy can select the multipath with larger signal-to-interference ratio value, for example, select one or several multipaths with the largest signal-to-interference ratio value as the multipath to be combined, or find the maximum value SIRmax in the signal-to-interference ratio values of all multipaths, set a threshold value th between 0 and 1, and combine all multipaths with the signal-to-interference ratio larger than SIRmax th. The complex path selection strategy needs to consider whether the true path is located on the sampling point of the searcher, since the searcher has precision, such as 1 chip (chip), that is, the sampling points of the searcher are distributed with 1 chip as an interval, the searched multipath is also with 1 chip as an interval, and the extended multipath is also with precision, which can be higher than or equal to the precision of the searcher. While true multipath (i.e., true path) positions are infinitely accurate. As shown in fig. 5, the true path on the left side of fig. 5 is located at the sampling point of the searcher, and the signal-to-interference ratio value of the true path has a significant maximum, and the true path can be selected as the multipath to be combined. The true path on the right side of fig. 5 is not located at the sample point, and the signal-to-interference ratio values of two multipaths near the true path are close. The two multipaths mentioned above may be selected as the multipaths that need to be combined.
The above process can also be expressed in the form of fig. 6-10, where the circles in fig. 6-14 indicate the multipaths that must be combined, the boxes indicate the multipaths that can participate in combining if the signal-to-interference ratio value exceeds a certain threshold, and the triangles indicate the multipaths that are not combined. The specific path selection strategy can be set by combining theoretical analysis, simulation and actual measurement results. The abscissa in fig. 6 to 14 represents the positions of the multipaths, and the ordinate represents the signal-to-interference ratio value of each multipath. Fig. 6-10 show the true path at the sample point. Fig. 11-14 show that the true path is not located at the sampling point, and the signal-to-interference ratio values of two multipaths near the true path are close to each other. The two multipaths mentioned above may be selected as the multipaths that need to be combined.
Step S414, according to the combining weight of the multipath to be combined, performing maximum ratio combining on the symbol-level data of the multipath data channel.
Step S416, demodulate and decode the combined symbol-level data to obtain information bits.
In this embodiment, due to the large computation amount of the matched filtering, the updating of the search result is not too fast, the updating period of the multipath search and the multipath extension is large, the updating period of the sir value calculation and the multipath selection is small, and the steps S408-S412 are repeated with the small updating period.
Corresponding to the above-mentioned method of multipath combining, the present embodiment provides an apparatus for multipath tracking, which is used to implement the above-mentioned embodiment. Fig. 15 is a block diagram of a multipath tracking apparatus according to an embodiment of the present invention, as shown in fig. 15, the apparatus including:
an expansion module 10, configured to expand a specified number of multipaths before and after the searched multipath position;
a signal-to-interference ratio obtaining module 12, connected to the spreading module 10, for obtaining the signal-to-interference ratio of each multipath after spreading by the spreading module 10;
a multipath selection module 14, connected to the sir value obtaining module 12, for selecting the multipath to be combined according to the sir value of each multipath obtained by the sir value obtaining module 12;
and a position tracking module 16, connected to the multipath selection module 14, for using the position of the selected multipath to be combined as the position of multipath tracking.
By the device, after the positions of the multipaths are searched, a specified number of multipaths are expanded in front of and behind the positions, then the signal-to-interference ratio of each expanded multipath is obtained, the multipath to be combined is selected according to the signal-to-interference ratio of each multipath, and finally the position of the multipath to be combined is selected as the position of multipath tracking.
After the spreading module 10 spreads a specified number of multipaths before and after the searched multipath position, the SIR value obtaining module 12 needs to obtain SIR (signal to interference power ratio, abbreviated as SIR value) of each multipath, and the SIR value needs to be calculated according to symbol-level data of a control channel of each multipath, so this embodiment provides a preferred embodiment, as shown in a specific structural block diagram of a multipath tracking apparatus shown in fig. 16, and the apparatus includes, in addition to the modules in fig. 15, the apparatus further includes: a symbol level data obtaining module 18, configured to perform descrambling and despreading operations on each multipath after spreading, and obtain symbol level data of a control channel of each multipath, where the signal-to-interference ratio obtaining module 12 further includes: and the sir value calculating unit 122 is configured to calculate the sir value of each multipath according to the symbol-level data of the control channel of each multipath acquired by the symbol-level data acquiring module 18.
After the sir value obtaining module 12 obtains the sir value of each multipath, the multipath selection module 14 needs to select a multipath to be combined, and for the selection mode of the multipath to be combined, this embodiment provides a preferred embodiment, that is, the multipath selection module 14 includes: the first selection unit is used for taking the multipath with the maximum signal-to-interference ratio value and the set number as the multipath needing to be combined; or, the second selection unit is used for judging whether the multipath searched before the expansion is positioned on the sampling point of the searcher, if so, the multipath positioned on the sampling point and a plurality of pairs of multipaths which are positioned on two sides of the multipath are taken as the multipath to be combined; if not, the multipath with the maximum signal-to-interference ratio value and the set number is taken as the multipath to be combined. Of course, the selection of the multipath to be combined is not limited to the above two ways, as long as the appropriate multipath to be combined can be selected.
After the multipath selection module 14 selects a suitable multipath to be combined, a maximum ratio combining operation needs to be performed according to the importance of the combining weight of the multipath, and therefore, this embodiment provides a preferred embodiment, where the apparatus further includes: and a maximal ratio combining module 20, configured to perform maximal ratio combining on the symbol-level data of the multipaths that need to be combined and are selected by the multipath selection module 14. After the maximal ratio combining module 20 performs maximal ratio combining on the selected multipath symbol-level data to be combined, it is also necessary to perform demodulation operation and decoding operation on the combined symbol-level data to obtain information bits. Accordingly, the above apparatus further comprises: and an information bit obtaining module 22, configured to perform demodulation operation and decoding operation on the combined symbol-level data to obtain information bits.
The symbol level data obtaining module 18 is further configured to obtain symbol level data of each multipath data channel, and the apparatus may perform the calculation of the combining weight according to the symbol level data of the data channel obtained by the symbol level data obtaining module 18, and therefore, the apparatus may further include: and the combining weight calculation module is used for calculating the combining weight of each multipath according to the symbol-level data of the control channel of each multipath.
After the combining weight calculation module calculates the combining weight of each multipath, the maximal ratio combining module 16 performs the maximal ratio combining operation, that is, the maximal ratio combining module 20 includes: and the maximum ratio combining unit is used for carrying out maximum ratio combining on the symbol-level data of the multipath data channel needing to be combined according to the combining weight of the multipath needing to be combined.
Fig. 17 is another block diagram of a multipath spreading and combining apparatus according to an embodiment of the present invention, and as shown in fig. 17, the apparatus includes the following modules:
and the multipath searching module is used for searching multipath positions after receiving the antenna data. The function of the multipath searching module is equivalent to that of the spreading module described above, and the multipath searching module obtains the multipath positions from the autocorrelation peaks based on the known chip-level data (typically, pilot sequences).
And a multipath spreading module for spreading one or several multipaths (for example, five multipaths) around the searched multipath position. The function of the multipath spreading module is equivalent to the function of spreading a specified number of multipaths before and after the positions of the searched multipaths by the spreading module in the above-described embodiment.
And the control channel descrambling and despreading module is used for descrambling and despreading each multipath after receiving the antenna data to obtain the symbol-level data of the control channel of each multipath. The function of the control channel descrambling and despreading module is equivalent to that of the symbol-level data acquisition unit in the above embodiment.
And the data channel descrambling and despreading module is used for descrambling and despreading each multipath after receiving the antenna data to obtain the symbol-level data of the data channel of each multipath. The function of the control channel descrambling and despreading module is equivalent to that of the data acquisition module in the above embodiment.
And the signal-to-interference ratio calculation module is used for calculating the signal-to-interference ratio of each multipath according to the symbol-level data of the control channel of the multipath. The function of the signal-to-interference ratio calculation module is equivalent to that of the signal-to-interference ratio calculation unit in the above-described embodiment.
And the combining weight calculation module is used for calculating the combining weight of each multipath according to the symbol-level data of the control channel of the multipath. The function of the combining weight calculating module is equivalent to that of the combining weight calculating module in the above embodiment.
And the multipath selection module is used for selecting the multipath needing to participate in the maximum ratio combination according to a certain algorithm based on the signal-to-interference ratio value of each multipath. This module is the core of the multipath combining process. The function of the multipath selection module is equivalent to that of the multipath selection module in the above-described embodiment.
And the maximum ratio combining module is used for carrying out maximum ratio combining on the multipath symbol-level data needing combining. The function of the maximal ratio combining module is equivalent to that of the maximal ratio combining module in the above embodiment.
And the demodulation decoding module is used for demodulating and decoding the result of the maximum ratio combination to obtain the information bit of the sending end. The function of the demodulation decoding module is equivalent to the function of the information bit obtaining module in the above embodiment. The multipath searcher is the basis for multipath expansion, and the symbol-level data obtained after descrambling and despreading operation is the basis for solving the signal-to-interference ratio and combining weight. The calculated combining weight and the descrambling and despreading operation of the data channel form the input of the maximum ratio combining module, and the information bit of the transmitting end can be obtained after the combined soft symbol is decoded.
It can be seen from the above description that, the present invention, on the premise of obtaining a rough multipath location by using a searcher, spreads the multipath and selects a suitable multipath according to the signal-to-interference ratio of the multipath for maximum ratio combining, thereby obtaining a more accurate multipath location. And the above process is smaller than the computation amount of multipath search through matched filtering in the related art, so that the method has a shorter updating period, can quickly track the change of multipath positions, prevents the performance degradation caused by the jitter of the multipath positions, and improves the peak rate of high-order modulation (such as 16QAM (16-order quadrature amplitude modulation)) under the low coding efficiency. Meanwhile, the invention can make the number of the combined multipath larger than the number of the searched multipath, and the extra multipath with larger signal-to-interference ratio can participate in the combination to provide extra gain, for example, under AWGN (additive white Gaussian noise) channel, the prior art only descrambles and despreads one multipath, and the invention can combine a plurality of multipaths, thereby obtaining better performance.
It will be apparent to those skilled in the art that the modules or steps of the present invention described above may be implemented by a general purpose computing device, they may be centralized on a single computing device or distributed across a network of multiple computing devices, and alternatively, they may be implemented by program code executable by a computing device, such that they may be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described may be performed in an order different than that described herein, or they may be separately fabricated into individual integrated circuit modules, or multiple ones of them may be fabricated into a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method of multipath tracking, comprising:
searching the positions of the multipath, and expanding the multipath with the specified number before and after the searched positions of the multipath;
acquiring the signal-to-interference ratio of each expanded multipath, and selecting the multipath to be combined according to the signal-to-interference ratio of each multipath;
and using the position of the selected multipath needing to be combined as the position of multipath tracking.
2. The method of claim 1,
before obtaining the signal-to-interference ratio value of each multipath, the method comprises the following steps: performing descrambling operation and despreading operation on each multipath after spreading to acquire symbol-level data of a control channel of each multipath;
acquiring the signal-to-interference ratio value of each multipath comprises the following steps: and calculating the signal-to-interference ratio of each multipath according to the symbol level data of the control channel of each multipath.
3. The method of claim 2, wherein selecting the multipath to be combined according to the signal-to-interference ratio value of each multipath comprises:
taking the multipath with the maximum signal-to-interference ratio value in the set number as the multipath to be combined; or,
judging whether the multipath searched before expansion is located on a sampling point of a searcher, if so, taking the multipath located on the sampling point and a plurality of pairs of multipaths symmetrically located at two sides of the multipath as the multipath to be combined; if not, the multipath with the maximum signal-to-interference ratio value and the set number is taken as the multipath to be combined.
4. The method according to claim 2, wherein after taking the selected position of the multipath to be combined as the position of multipath tracking, the method further comprises:
carrying out maximum ratio combination on the selected multipath symbol-level data needing to be combined;
and carrying out demodulation operation and decoding operation on the combined symbol-level data to obtain information bits.
5. The method of claim 4, wherein obtaining symbol-level data for the control channel for each multipath further comprises: obtaining symbol-level data of each multipath data channel;
after obtaining the signal-to-interference ratio value of each multipath, the method further comprises: calculating the combining weight of each multipath according to the symbol-level data of the control channel of each multipath;
the maximum ratio combining of the selected multipath symbol level data to be combined comprises the following steps: and carrying out maximum ratio combination on the symbol-level data of the multipath data channel to be combined according to the combining weight of the multipath to be combined.
6. An apparatus for multipath tracking, comprising:
the expansion module is used for searching the positions of the multipath and expanding the multipath with the specified number before and after the searched positions of the multipath;
a signal-to-interference ratio acquisition module, configured to acquire the signal-to-interference ratio of each multipath after being expanded by the expansion module;
a multipath selection module, configured to select a multipath to be combined according to the signal-to-interference ratio of each multipath obtained by the signal-to-interference ratio obtaining module;
and the position tracking module is used for taking the selected position of the multipath needing to be combined as the position of multipath tracking.
7. The apparatus of claim 6,
the device further comprises: a symbol level data acquisition module, configured to perform descrambling and despreading operations on each multipath after spreading, and acquire symbol level data of a control channel of each multipath;
the signal-to-interference ratio acquisition module comprises: and the signal-to-interference ratio calculating unit is used for calculating the signal-to-interference ratio of each multipath according to the symbol level data of the control channel of each multipath acquired by the symbol level data acquiring module.
8. The apparatus of claim 7, wherein the multipath selection module comprises:
the first selection unit is used for taking the multipath with the maximum signal-to-interference ratio value and the set number as the multipath needing to be combined; or,
the second selection unit is used for judging whether the multipath searched before expansion is positioned on a sampling point of the searcher or not, and if so, taking the multipath positioned on the sampling point and a plurality of pairs of multipaths which are positioned on two sides of the multipath and are symmetrical as the multipath to be combined; if not, the multipath with the maximum signal-to-interference ratio value and the set number is taken as the multipath to be combined.
9. The apparatus of claim 7, further comprising:
a maximum ratio combining module, configured to perform maximum ratio combining on the multipath symbol-level data that needs to be combined and is selected by the multipath selection module;
and the information bit acquisition module is used for demodulating and decoding the combined symbol-level data to obtain information bits.
10. The apparatus of claim 9,
the symbol level data acquisition module is further configured to acquire symbol level data of each multipath data channel;
the device further comprises: a combining weight calculation module, configured to calculate a combining weight of each multipath according to the symbol-level data of the control channel of each multipath;
the maximum ratio combining module comprises: and the maximum ratio combining unit is used for carrying out maximum ratio combining on the symbol-level data of the multipath data channel needing to be combined according to the combining weight of the multipath needing to be combined.
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| CN1464638A (en) * | 2002-06-11 | 2003-12-31 | 上海贝尔有限公司 | Multipath selection deciding method and apparatus for Rake receiver |
| CN1684373A (en) * | 2004-04-13 | 2005-10-19 | 上海明波通信技术有限公司 | Multipath searching method and its device in mobile communication system |
| US20060050773A1 (en) * | 2004-09-09 | 2006-03-09 | Kabushiki Kaisha Toshiba | Receiving apparatus and method for receiving and processing spread spectrum radio signals |
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| US20040072553A1 (en) * | 2002-09-20 | 2004-04-15 | Xiaohui Wang | Methods, systems, and computer program products for selecting delay positions for a RAKE receiver by adjusting the delay positions based on comparisons of signal to interference ratios and/or powers for multi-path signals over time |
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| CN1464638A (en) * | 2002-06-11 | 2003-12-31 | 上海贝尔有限公司 | Multipath selection deciding method and apparatus for Rake receiver |
| CN1684373A (en) * | 2004-04-13 | 2005-10-19 | 上海明波通信技术有限公司 | Multipath searching method and its device in mobile communication system |
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