WO2010060355A1

WO2010060355A1 - Transmitting method and apparatus of multi-antenna broadcast

Info

Publication number: WO2010060355A1
Application number: PCT/CN2009/074920
Authority: WO
Inventors: 王艺; 陈大庚
Original assignee: 华为技术有限公司
Priority date: 2008-11-25
Filing date: 2009-11-12
Publication date: 2010-06-03
Also published as: CN101741797A; CN101741797B

Abstract

A transmitting method of multi-antenna broadcast is provided in the embodiment of the present invention, the method includes: performing channel coding for at least two service data stream respectively; multiplexing the service data stream being channel coded as one service data stream by hierarchical modulation; performing transmitting diversity processing for the multiplexed service data stream to obtain multiple data corresponding to the number of the transmitting antenna; and sending the multiple data to the corresponding transmitting antenna. A transmitting apparatus of the multi-antenna broadcast is provided in the embodiment of the present invention. With the embodiment of the present invention, multi-antenna technology is introduced in a broadcast channel, signal interfere ratio of the receiver is increased by adopting transmitting diversity mode, and channel capacity and spectrum efficiency are enhanced by combining hierarchy modulation with MIMO.

Description

The present invention claims the priority of the Chinese patent application filed on November 25, 2008, the Chinese Patent Application No. 200810219373.2, entitled "Multi-antenna Broadcast Transmission Method and Apparatus", all of which are filed on November 25, 2008. The content is incorporated herein by reference. TECHNICAL FIELD The present invention relates to the field of communications, and in particular, to a method and an apparatus for transmitting a multi-antenna broadcast. Background technique

Multi-Input Multi-Output (MIMO) technology is an important technology for third-generation and future mobile communication systems to achieve high data rates, large system capacity, and improved transmission quality. This technology can double the capacity and spectrum utilization of a communication system without increasing bandwidth.

The core of MIMO systems is the use of multiple antennas to suppress channel fading. Usually, multipath causes fading and is therefore considered a detrimental factor. But for MIMO systems, multipath can be used as a benefit factor. Figure 1 shows the schematic of a MIMO system. The transport stream s(k) is space-time coded to form N information substreams d(k), i=l, ..., Ν. The substreams are transmitted by one antenna and received by the receiving antennas after the spatial channel. The multi-antenna receiver utilizes space-time coding to separate and decode these data substreams for optimal processing. The transmitted substreams are simultaneously transmitted to the channel and occupy the same frequency band, thus not increasing the bandwidth. If the channel responses between the transmit and receive antennas are independent, the MIMO system can create multiple parallel spatial channels. If information is transmitted independently through these parallel spatial channels, the data rate can be improved; if the same information is transmitted through these parallel spatial channels, spatial diversity gain can be obtained, and performance can be improved. Currently, the methods for obtaining spatial diversity include Spatial Time Block Code (STBC) and Spatial Frequency Block Code (SFBC).

The broadcast channel is characterized by a downlink to point-to-multipoint transmission. The typical scene is within the cell, there is one a base station and a plurality of mobile terminals, the base station simultaneously transmitting broadcast signals to the plurality of mobile terminals. When the base station transmits a broadcast signal, it does not know the information of the mobile terminal, such as the number of mobile terminals, the channel condition of the mobile terminal, and the like. At present, the broadcast channel only considers single-antenna transmission. With the development of communication technologies, especially the MIMO technology, considering multi-antenna transmission in the broadcast channel, improving performance and spectrum efficiency, has become a research hotspot.

Hierarchy Modulation (HM) is an enhanced modulation technology that has been moved by Ultra Mobile Broadband (UMB), Digital Video Broadcasting (DVB), MediaFLO (Qualcomm's Mobile TV Standard) And other standards adopted. Hierarchical modulation can achieve maximum broadcast channel capacity in a single antenna scenario, or one of the best ways to obtain broadcast channel capacity.

The typical implementation block diagram of HM is shown in Figure 2:

Two different service flows (traffic flow 1 and service flow 2) are multiplexed by channel modulation and data of two different service flows. The multiplexing method can assign two highly reliable bits of 16QAM (Quadature Amplitude Modulation) to service flow 1 and two low-reliability bits to service flow 2; or two different services. After the Quadrature Phase Shift Keying (QPSK) modulation is performed, the power and phase control are superimposed to achieve multiplexing of different service data streams.

However, the inventors have found that multi-antenna technology is not introduced in the current broadcast channel, resulting in low performance and spectral efficiency; hierarchical modulation and MIMO are also not combined, so that hierarchical modulation can only achieve the maximum broadcast channel capacity in a single antenna scenario. . Summary of the invention

In view of this, embodiments of the present invention provide a method and apparatus for transmitting multi-antenna broadcast, combining hierarchical modulation with MIMO to improve channel capacity and spectrum efficiency.

An embodiment of the present invention provides a method for transmitting a multi-antenna broadcast, including:

Performing channel coding on at least two service data streams respectively; And the channel-encoded service data stream is multiplexed into one-way service data stream by hierarchical modulation; and the multiplexed service data stream is subjected to transmit diversity processing to obtain multiplexed data corresponding to the number of transmit antennas;

Transmitting the multiplexed data to a corresponding transmit antenna.

The embodiment of the invention further provides a device for transmitting a multi-antenna broadcast, comprising:

a channel coding module, configured to separately perform channel coding on at least two service data streams;

a hierarchical modulation module, configured to multiplex the channel-encoded service data stream into a one-way service data stream;

a transmit diversity module, configured to perform transmit diversity processing on the multiplexed service data stream, to obtain multiplex data corresponding to the number of transmit antennas;

At least two transmit antennas are configured to send the multiplexed data to the receiving end.

In the embodiment of the present invention, a multi-antenna technology is introduced under the broadcast channel, and the signal-to-noise ratio of the receiver is improved by using the transmit diversity method, and the hierarchical modulation is combined with the MIMO to improve the channel capacity and the spectrum efficiency. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a basic block diagram of a prior art MIMO system;

2 is a schematic diagram of prior art level modulation;

3 is a schematic flowchart of a method for transmitting a multi-antenna broadcast according to an embodiment of the present invention;

4 is a schematic diagram of a 16QAM rule constellation diagram and a mapping manner thereof in the first embodiment of the present invention; FIG. 5 is a constellation diagram formed by superimposing two layers of QPSK in the first embodiment of the present invention;

6 is a schematic diagram of an Alamouti method for two pairs of transmitting antennas according to Embodiment 1 of the present invention;

7 is a schematic diagram of delayed transmit diversity in Embodiment 1 of the present invention;

8 is a schematic diagram of angular deflection transmit diversity in Embodiment 1 of the present invention;

9 is a schematic flowchart of a method for transmitting a multi-antenna broadcast according to Embodiment 2 of the present invention; 10 is a schematic flowchart of a method for transmitting a three-multiple antenna broadcast according to an embodiment of the present invention; FIG. 11 is a schematic structural diagram of a fourth multi-antenna broadcast transmitting apparatus according to an embodiment of the present invention;

FIG. 12 is a schematic structural diagram of an apparatus for transmitting a multi-antenna broadcast according to Embodiment 4 of the present invention; FIG. 13 is a schematic diagram showing a further improvement of a transmitting apparatus for multi-antenna broadcasting according to Embodiment 4 of the present invention;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Embodiment 1 of the present invention:

Referring to FIG. 3, a method for transmitting a multi-antenna broadcast according to an embodiment of the present invention includes: Step 31: Perform channel coding on at least two service data streams respectively.

In this embodiment, N ( N > 2 ) service data streams are involved, and channel coding includes but is not limited to: Turbo code, LDPC code (low density parity check code), or convolutional code. The channel coding methods selected for different service data streams may be the same or different.

Step 32: The coded service data stream is multiplexed into one channel data stream by hierarchical modulation. In this embodiment, the manner of hierarchical modulation includes but is not limited to: (1) assigning bit bits of different reliability of the rule or irregular QAM to different service flows; or (2) adopting basic modulation of traffic flows of different layers. Ways, such as QPSK, are superimposed by different power or angles.

For mode (1), rule QAM is taken as an example, rule QAM is a high-order modulation mode currently used, and FIG. 4 is a rule 16QAM modulation mode used in UMB (refers to a QAM modulation mode including 16 symbols), a constellation The distribution shape is a square, and the distance between adjacent rows and adjacent columns is equal.

For mode (2), the traffic of different layers is modulated by QPSK, and the constellation diagram (from UMB) is obtained by superimposing different powers or angles. As shown in FIG. 5, "for the amplitude of the first service flow, P is the first The magnitude of the two business flows is the angle between the two business flows.

Step 33: Perform multiplexing diversity processing on the multiplexed service data stream to obtain the number of transmitting antennas. In this embodiment, the transmit diversity includes but is not limited to: a space time block code STBC or a space frequency block code SFBC, a delayed transmit diversity, an angular deflection transmit diversity, a time switched transmit diversity or a frequency switched transmit diversity, or a different transmit diversity. Combine and so on. The following are introduced separately.

1, space time block code STBC or space frequency block code SFBC

The basic principle of space-time block code and space-frequency block code is the same. The space-time block code puts the signal into two dimensions of space and time, while the space-frequency block code puts the signal into two dimensions of space and frequency domain. The methods are the same.

For example, for the diversity mode of two transmit antennas, the Alamouti method (specifically, the space-time block code or the space-frequency block code of two transmit antennas) is processed as shown in FIG. 6, and the input symbols are for the antenna 1, and the output is The symbol is that for antenna 2, the output symbol is [, if the output symbol is a space-time block code in different time dimensions, if it is a space-frequency block code at a different frequency.

In this embodiment, space diversity and time diversity are implemented on the multiplexed service data stream by using spatial and temporal coding, and spatial and frequency coding is used to implement spatial diversity and frequency diversity, thereby reducing channel error rate. In the secondary transmit antenna scenario, a higher diversity gain can be obtained.

2. Delayed transmit diversity

The delayed transmit diversity is shown in Figure 7, which is to divide the multiplexed service data streams into copies of different delays and transmit them on different antennas. For example, for antenna 1, transmit at time t1; for antenna 2, delay Δt, transmit at time t1 + A t; for antenna k, delay (k-l) * A t, at time t1 + (kl) * A t send.

3, angular deflection transmit diversity

The angular deflection transmit diversity is shown in Figure 8, which is to divide the multiplexed traffic data streams into copies of different angles and transmit them on different antennas. For example, for antenna 2, the angle is transmitted at the angle of antenna 1 and the angle is transmitted; for antenna k, the angle of deflection is transmitted.

4, choose the transmit diversity

Selecting transmit diversity usually includes time-switching transmit diversity and frequency-switching transmit diversity. When the sender does not know the channel information, the sender can randomly select the antenna to transmit, and randomly select the time. Selective transmission is time switching transmit diversity, and frequency selection is frequency switching transmit diversity.

5. Combination of different transmit diversity

According to the foregoing description of the four types of transmit diversity, the following is a description of the combination of space-time block code and time-switched transmit diversity, and those skilled in the art understand and can freely select other combinations of transmit diversity.

Antenna transmission (time-switched transmit diversity) is randomly selected at different times, for example, antenna 1 is selected for transmission at time t1, antenna 2 is selected for transmission at time t2, and space-time block code is used for transmission when antenna 1 is transmitted at time t1. The spatial and temporal coding implements spatial diversity and time diversity; when transmitted by antenna 2 at time t2, space-time block code is also used, and spatial and temporal coding is used to implement spatial diversity and time diversity.

Step 34: Send the multiplexed data to a corresponding transmit antenna.

The multiplexed data corresponding to the number of transmitting antennas is obtained by the transmit diversity process, and is transmitted to the corresponding transmitting antenna for transmission to the receiving side. It should be understood that the transmission method of the multi-antenna broadcast of the present embodiment is applicable not only to the case where the receiving side (e.g., mobile terminal) has two or more receiving antennas, but also to the case where the receiving side has only one receiving antenna.

In the embodiment of the present invention, a multi-antenna technology is introduced under the broadcast channel, and the signal-to-noise ratio of the receiver is improved by using the transmit diversity method, and the hierarchical modulation is combined with the MIMO to improve the channel capacity and the spectrum efficiency. Embodiment 2 of the present invention:

Referring to FIG. 9, the method for transmitting a multi-antenna broadcast according to the second embodiment of the present invention combines OFDM (Orthogonal Frequency Division Multiplexing) with MIMO, and is different from Embodiment 1 in this embodiment. After the multiplexed service data stream is processed by the transmit diversity process to obtain data corresponding to the at least two transmit antennas, the data is not directly sent to the transmit antenna, but is first modulated by OFDM and then transmitted to the transmit antenna.

Step 91: Perform channel coding on at least two service data streams respectively.

Step 92: The channel-encoded service data stream is multiplexed into one-way service data stream by hierarchical modulation. Step 93: Perform transmit diversity processing on the multiplexed service data stream to obtain multiplexed data corresponding to the number of transmit antennas.

Steps 91-93 are the same as steps 31-33 in the first embodiment, and are not described here.

Step 94: Perform OFDM modulation on the multiplexed data separately.

OFDM modulation can divide a channel into orthogonal sub-channels, convert high-speed data signals into parallel low-speed sub-data streams, and modulate them for transmission on each sub-channel. The bandwidth of each subchannel is very narrow, so that each subchannel can be regarded as flatness fading, thereby suppressing intersymbol interference and combining well with multiple antennas.

Step 95: Send the OFDM modulated multiplex data to the corresponding transmit antenna. This step is substantially the same as step 34 of the first embodiment. In step 34, the multiplexed data sent to the transmit antenna is data obtained by the transmit diversity process, without OFDM modulation; the multiplexed data sent to the transmit antenna in this step It is data that is subjected to transmit diversity processing and OFDM modulation.

As a further improvement of the embodiment, after the channel coding is performed on the at least two service data streams in step 91, the method further includes the following steps:

Interleaving processing is performed on the channel-encoded service data streams.

The interleaving process is to obtain time-diversity by disturbing the bit-correlation and randomization of the code-word sequence of the service data stream after channel coding, so as to obtain multiplexing in the case of hierarchical modulation, and to process data of each channel. The interleaving of streams may be the same or different.

After the interleaving process, step 92 is performed to multiplex the service data stream into a data stream by hierarchical modulation.

This embodiment combines OFDM and MIMO to improve not only diversity gain and channel capacity, but also OFDM to convert frequency selective fading into flat fading on subcarriers, which can eliminate intersymbol interference. Embodiment 3 of the present invention:

Referring to FIG. 10, the method for transmitting the third multi-antenna broadcast in the embodiment of the present invention is different from the second embodiment in that, in this embodiment, the multiplexed service data stream is obtained by using transmit diversity processing and at least two. After the corresponding data of the secondary transmitting antenna, the pilot and carrier mapping are inserted, and then OFDM modulation is performed, and then transmitted to the transmitting antenna.

Step 101: Perform channel coding on at least two service data streams respectively.

Step 102: The channel-encoded service data stream is multiplexed into a one-way service data stream by hierarchical modulation.

Step 103: Perform transmit diversity processing on the multiplexed service data stream to obtain multiplexed data corresponding to the number of transmit antennas.

Steps 101-103 are the same as steps 91-93 in the second embodiment, and are not described here.

Step 104: Insert a pilot and a carrier map into the multiplexed data.

The carrier mapping is to map each channel data into an OFDM symbol, and the insertion pilot is to insert the known information into the time-frequency resource block composed of the OFDM symbol, and the pilot is estimated according to the fading condition of the pilot position. The fading of the entire channel time-frequency resource block to the receiving end. The pilot carrier does not transmit any useful signal stream, and can resist various interferences. The channel estimation can facilitate the receiver to obtain the predicted result, and can understand the distortion of the frequency and phase of each carrier, and then the receiver can correct the signal according to the information. The amplitude and phase are corrected, that is, channel equalization.

Step 105 is basically the same as step 94 in the second embodiment, that is, OFDM modulation is performed on the inserted pilot and carrier mapped multiplexed data respectively.

The step 106 is basically the same as the step 95 in the second embodiment, that is, the multiplexed data after the OFDM modulation is sent to the corresponding transmitting antenna.

Similarly, as a further improvement of the embodiment, after the channel coding is performed on the at least two service data streams in step 101, the method further includes the following steps:

Interleaving processing is performed on the encoded service data streams.

This embodiment combines OFDM and MIMO to improve not only diversity gain and channel capacity, but also OFDM to convert frequency selective fading into flat fading on subcarriers, which can eliminate intersymbol interference. Disturb. At the same time, before the OFDM modulation, the interpolated pilot and carrier mapping processing is performed on the multiplexed data, which is more advantageous for the channel equalization at the receiving end. Embodiment 4 of the present invention:

Referring to FIG. 11, a transmitting apparatus for a multi-antenna broadcast according to an embodiment of the present invention includes: a channel coding module 11 configured to separately perform channel coding on at least two service data streams.

In this embodiment, k ( k > 2 ) service data streams are involved, and channel coding includes but is not limited to: Turbo code, LDPC code (low density parity check code), or convolutional code. For different service data streams, the channel coding modes selected by the channel coding module 11 may be the same or different.

The hierarchical modulation module 12 is configured to multiplex the channel-encoded service data stream into a one-way service data stream.

In this embodiment, the hierarchical modulation module performs hierarchical modulation, including but not limited to: (1) assigning bits of different reliability of the rule or the irregular QAM to different service flows; or (2) different layers of service flows. Use basic modulation methods, such as QPSK, to superimpose through different power or angles.

The transmit diversity module 13 is configured to perform transmit diversity processing on the multiplexed service data stream to obtain multiplexed data corresponding to the number of transmit antennas.

In this embodiment, the transmit diversity module 13 may specifically include:

a space time block code module for performing spatial diversity and time diversity on the multiplexed service data stream by using spatial and temporal coding; or

a space frequency block code module for performing spatial diversity and frequency diversity on the multiplexed service data stream using space and frequency coding; or

a delayed transmit diversity module, configured to diversity the multiplexed service data streams into copies of different delays for transmission on different transmit antennas; or

An angular deflection transmit diversity module, configured to divide the multiplexed service data streams into copies of different angles for transmission on different transmit antennas; or

The time switching transmit diversity module is configured to perform random selection of the transmit antenna transmission in time; or the frequency switch transmit diversity module, configured to perform random selection of the transmit antenna transmission on the frequency. In a practical application scenario, the transmit diversity module 13 may be specifically a combination of any of the foregoing diversity modules or any of the diversity modules.

At least two transmit antennas 14 are configured to transmit the multiplexed data to the receiving end.

In this embodiment, the number of transmitting antennas is N ( Ν > 2 ), and the transmission through multiple antennas can effectively suppress channel fading.

Referring to FIG. 12 again, as a further improvement of the embodiment, the transmitting apparatus of the multi-antenna broadcast further includes:

The Orthogonal Frequency Division Multiplexing (OFDM) OFDM modulating module 15 is disposed between the transmit diversity module 12 and the transmit antenna 14 for performing OFDM modulation on the multiplexed data obtained by the diversity processing of the transmit diversity module 12.

Referring to FIG. 13, as a further improvement of the embodiment, the transmitting apparatus of the multi-antenna broadcast further includes:

The interpolating pilot and carrier mapping module 17 is disposed between the transmit diversity module 12 and the OFDM modulation module 15 for mapping the multipath data obtained by the diversity processing of the transmit diversity module 12 into an OFDM symbol, respectively, in an OFDM symbol. A pilot is inserted into the composed time-frequency resource block, and the fading of the entire channel time-frequency resource block from the transmitting end to the receiving end is estimated according to the fading condition of the position of the pilot. In order to facilitate the channel to perform channel equalization according to channel estimation.

For the transmitting apparatus of the multi-antenna broadcast shown in FIG. 11-13, an interleaving module 16 for setting the service data stream encoded by the channel encoding module 11 may be further disposed between the channel coding module 11 and the hierarchical modulation module 12. The interleaving process is separately performed, which is to facilitate the multiplexing of the hierarchical modulation module 12 by scrambling the bit-independent correlation of the channel-coded service data stream codewords to obtain time diversity. For the different service data streams, the manner in which the interleaving module 16 performs the interleaving process may be the same, or the multi-antenna technology may be introduced into the broadcast channel in different embodiments of the present invention, and the method of transmitting diversity is used to improve the connection. The signal-to-noise ratio of the receiver combines hierarchical modulation with MIMO to improve channel capacity and spectral efficiency. A person skilled in the art can understand that all or part of the steps of implementing the above method embodiments may be completed by using hardware related to program instructions, and the foregoing program may be stored in a computer readable storage medium, and the program is executed when executed. The foregoing steps include the steps of the foregoing method embodiments; and the foregoing storage medium includes: a medium that can store program codes, such as a ROM, a RAM, a magnetic disk, or an optical disk.

The above is only the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any change or replacement that can be easily conceived by those skilled in the art within the technical scope of the present invention is All should be covered by the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

Rights request

A method for transmitting a multi-antenna broadcast, comprising:

Performing channel coding on at least two service data streams respectively;

And the channel-encoded service data stream is multiplexed into one-way service data stream by hierarchical modulation; and the multiplexed service data stream is subjected to transmit diversity processing to obtain multiplex data corresponding to the number of transmit antennas;

Transmitting the multiplexed data to a corresponding transmit antenna.

2. The method according to claim 1, wherein: the method of hierarchical modulation is specifically one of the following ways:

Allocating bits of different reliability of regular or irregular quadrature amplitude modulation QAM to different traffic flows; or

Traffic of different layers is modulated in a basic modulation mode with different power or angles.

3. The method according to claim 1, wherein: the manner of transmitting the diversity is specifically one or any combination of the following manners:

Spatial and temporal coding is performed on the multiplexed service data stream using spatial and temporal coding; or

Spatial diversity and frequency diversity are achieved by multiplexing the spatial and frequency codes for the multiplexed traffic data stream; or

Diversity of multiplexed business data streams into copies of different time delays; or

Divide the multiplexed business data streams into copies of different angles; or

According to the feedback from the receiving end to the channel quality of the transmitting antenna, the transmitting antenna is randomly selected for transmission.

The method according to claim 1, wherein: after the multiplexed service data stream is subjected to transmit diversity processing to obtain multiplex data corresponding to the number of transmit antennas, the method further includes:

The multiplexed data is separately subjected to OFDM modulation.

The method according to claim 4, wherein: the multiplexed service data stream is subjected to transmit diversity processing to obtain multiplexed data corresponding to the number of transmit antennas, and then the multiplexed data is separately performed. Before OFDM modulation, it also includes: A pilot and carrier map is inserted for the multiplexed data.

The method according to claim 4 or 5, wherein after the channel coding is performed on the at least two service data streams, the method further includes:

A transmitting device for multi-antenna broadcasting, comprising:

8. The apparatus according to claim 7, wherein: the transmit diversity module is specifically:

The time switching transmit diversity module is configured to perform random selection of the transmit antenna transmission in time; or the frequency switch transmit diversity module, configured to perform random selection of the transmit antenna transmission on the frequency.

9. The apparatus according to claim 7, further comprising:

An Orthogonal Frequency Division Multiplexing (OFDM) OFDM modulation module is configured to perform OFDM modulation on the multiple data obtained by the diversity processing of the transmit diversity module.

10. The device according to claim 9, further comprising: Inserting a pilot and carrier mapping module, configured to map the multiplexed data obtained by the diversity processing of the transmit diversity module into an OFDM symbol, insert a pilot into a time-frequency resource block composed of OFDM symbols, and perform fading according to a location of the pilot. The situation estimates the fading of the entire channel time-frequency resource block from the transmitting end to the receiving end.

11. The apparatus according to claim 9 or 10, further comprising:

And an interleaving module, configured to separately perform interleaving processing on the service data stream encoded by the channel coding module.