CN100399720C - Multi-antenna communication method and communication system adaptively adjusted according to channel spatial correlation - Google Patents

Abstract

A multi-antenna communication method and communication system adaptively adjusted according to channel spatial correlation, relating to a communication method for a multi-antenna system. Its communication method includes: sending control signaling, detecting channel state information; selecting an initial transmission scheme for communication; transmitting business information; monitoring channel changes and switching transmission schemes during communication, and coordinating both parties in communication. Its communication system includes control signaling information transmitter, receiver and business information transmitter, receiver. The present invention uses the spatial correlation of the channel as the judgment basis for switching the transmission scheme. When the channel spatial correlation is strong, the smart antenna scheme is adopted, and when the channel spatial correlation is weak, the V-BLAST scheme is adopted, so that when the channel spatial correlation changes Downlink communication can maintain a high transmission rate and good communication quality, and can sensitively reflect channel changes to ensure the accuracy and timeliness of transmission mode switching; control signaling and business information adopt different coding methods and different The transmission of the scheme can realize the effective transmission of control information all the time, which can improve the reliability of the system.

Description

Multi-antenna communication method and communication system adaptively adjusted according to channel spatial correlation

technical field

The invention relates to a multi-antenna communication method adaptively adjusted according to channel space correlation, which belongs to the technical field of communication, and in particular relates to a communication method of multi-antenna technology in the communication technology.

Background technique

Multi-antenna technology is a hot technology in current wireless communication technology, mainly including Multiple Input Multiple Output (MIMO) technology and Smart Antennas (Smart Antennas) technology.

MIMO technology adopts space-time coding. According to the classification of space-time codes used, there are two main categories: space-time trellis codes (Space Time Trellis Codes, STTC) and space-time block codes (Space Time Block Codes, STBC) based on transmit diversity. ; Layered Space Time Codes (LSTC) based on non-transmit diversity.

Space-time trellis code is a design that comprehensively considers channel coding, modulation, transmit diversity and receive diversity, and can provide a coding method with greater coding gain, spectrum utilization and diversity gain. The performance of the space-time trellis code is very good, but its decoding complexity is quite high. Specifically, when the number of transmit antennas is fixed, the decoding complexity of space-time trellis codes (measured by the number of trellis states of the decoder) increases exponentially with the transmission rate. In view of this, Alamouti proposed a simple two-antenna transmit diversity scheme, and gave a relatively simple decoding algorithm. Inspired by it, Tarkh et al. applied the orthogonality theory and extended the scheme to the transmit diversity system with any number of transmit antennas, thus proposed the space-time block code. Compared with space-time trellis codes, space-time block codes have much lower decoding complexity, although their performance is reduced.

The following takes the classic Alamouti 2 send 1 receive scheme as an example to illustrate the encoding and decoding process of the space-time block code. The code streams of the transmitted data sent to the space-time block coding module are c ₁ , c ₂ , ... and the code streams are coded in groups of 2. After passing through the space-time block coder, the output coding matrix is: $\left[\begin{array}{cc}{c}_1& -{c^{*}}_2\\ c_2& {c^{*}}_1\end{array}\right],$ The rows of the matrix represent transmitting antennas, and the columns represent time slots. The specific encoding principle is shown in Figure 1. In the case of 2 transmissions and 1 reception, the signal received by the receiving antenna is:

$\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; =</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="C20051002153900142.png,C20051002153900161.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="c"\; filenames="C20051002153900142.png,C20051002153900161.png"\; state="\{\{state\}\}">c</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; *</span>}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="C20051002153900142.png,C20051002153900161.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\end{array}\right]<span\; class="notranslate">\; +</span>\begin{array}{c}\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="no"\; filenames="C20051002153900142.png,C20051002153900161.png"\; state="\{\{state\}\}">no</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}\right]\end{array}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

r ₁ , r ₂ represent the signals received by the receiving antennas in time slots 1 and 2, respectively, and h ₁ , h ₂ are the channel impulse responses corresponding to transmitting antennas 1 and 2, respectively. set up $\mathrm{the\; y}=\left[\begin{array}{c}{r}_1\\ r_2^{*}\end{array}\right],$ Then y can be expressed as

$\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}& {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\\ {\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; *</span>}& {<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; *</span>}\end{array}\right]\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}\right]<span\; class="notranslate">\; +</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="no"\; filenames="C20051002153900142.png,C20051002153900161.png"\; state="\{\{state\}\}">no</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{<span\; class="notranslate">\; *</span>}\end{array}\right]<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

set up $h=\left[\begin{array}{cc}{h}_1& h_2\\ h_2^{*}& {-\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="C20051002153900142.png,C20051002153900161.png"\; state="\{\{state\}\}">h</figure-callout>}}_1^{*}\end{array}\right],$ Multiply H ^H by the left of (2), because $h^{h}h={\left|\right|h\left|\right|}_f^2{I}_2,$ Estimated value of emission data can be obtained From the above space-time block decoding process, it can be seen that due to the orthogonal design of the transmitting code block, only a linear transformation of the received signal is required during decoding, and there is no special requirement for the channel matrix. Therefore, the multi-antenna communication method using space-time block coding is less affected by the change of channel spatial correlation, but its spectrum utilization is lower than that of layered space-time code.

Hierarchical space-time code is a technology that divides the source data into several parallel sub-data streams and encodes and modulates them independently, so it is not based on transmit diversity. Foschini et al. of Bell Labs first proposed a Diagonally Bell Labs Layered Space-Time Wireless Communication Architecture (D-BLAST). The transmitted information is coded diagonally in space-time. Under the Rayleigh fading environment, this structure has obtained a huge theoretical capacity, and its capacity increases linearly with the number of transmitting antennas, and can reach 90% of the Shannon channel capacity, although D-BLAST has better space-time characteristics and hierarchical structure , but one of its defects is that the complexity is too high to be suitable for application. Subsequently, the horizontal layered space-time code H-BLAST (Horizontal BLAST) and the vertical layered space-time code V-BLAST (VerticalBLAST) were proposed. Although the decoding of H-BLAST is simple, its space-time characteristics are relatively poor; while V- BLAST has better performance and less decoding complexity, so it is widely used.

The following describes the encoding and decoding process of V-BLAST. The equivalent baseband model of the V-BLAST system is shown in Figure 2. The transmitted data 1 first passes through the V-BLAST encoding module 5 to encode the transmitted data 1 into parallel M data symbol streams. After passing through the wireless channel, it is encoded at the receiving end N receiving antennas receive at the same time, perform zero-forcing detection on the received signal, and finally output the data. The M-dimensional vector of the equivalent baseband transmit signal is defined as a=(a ₁ a ₂ ...a _M ) ^T , a _k represents the data of the kth transmit antenna, and the corresponding received signal vector is r=(r ₁ r ₂ ...r _N ) ^T , which can be expressed as

r＝Ha+N (3)

为 in h _{i, j} represents the channel fading factor from the j-th transmit antenna to the i-th receive antenna, assuming that different hij are independent of each other, and N represents the Gaussian noise vector at the receiving end. The direct inverse zero-tracking detection method is expressed as follows, the estimated value of the transmitted signal vector

for

表示矩阵的Moore-Penrose逆。该方法的原理是直接对信道矩阵进行求逆操作，然后用该逆矩阵左乘接收的信号矢量，再同时对各个分量进行译码，可见直接求逆的方法要求信道矩阵列满秩。V-BLAST的另一种检测算法为排序干扰对消(Ordered SuccessiveInterference Cancellation，OSIC)，其具体方法详见G.D.Golden，C.J.Foschini，“Detectionalgorithm and initial laboratory results using V-BLAST space-time communication architecture”，IEEE ECTRONICS LETTERS 7^th Jan 1999，Vol.35 No.1.由上述V-BLAST的编码译码算法可以看出V-BLAST的频谱利用率较高，但其受信道空间相关性的影响较大。in,

Represents the Moore-Penrose inverse of a matrix. The principle of this method is to directly invert the channel matrix, and then use the inverse matrix to multiply the received signal vector to the left, and then decode each component at the same time. It can be seen that the direct inversion method requires the channel matrix to be of full rank. Another detection algorithm of V-BLAST is Ordered Successive Interference Cancellation (OSIC). For the specific method, see GDGolden, CJFoschini, "Detection algorithm and initial laboratory results using V-BLAST space-time communication architecture", IEEE ECTRONICS LETTERS 7 ^th Jan 1999, Vol.35 No.1. From the above V-BLAST encoding and decoding algorithm, it can be seen that V-BLAST has a higher spectrum utilization rate, but it is greatly affected by channel spatial correlation.

The core of smart antenna technology is adaptive beamforming, which uses the positional relationship between the units in the antenna array, that is, the phase relationship of the signal, and forms the antenna beam pattern by weighting, combining and other methods to make the main beam direction point signal direction while suppressing interference in other directions. The principle is detailed in "Adaptive Filtering", edited by Gong Yaohuan, Electronic Industry Press, 2003.7.

A problem existing in the current multi-antenna technology is that different multi-antenna technologies are suitable for different channel conditions, and none of the multi-antenna technologies can achieve high performance in the case of strong channel spatial correlation and weak channel spatial correlation. transmission rate and better communication quality. Due to the use of transmit diversity and receive diversity, MIMO technology can achieve higher channel capacity and better performance when the channel spatial correlation is weak, especially when the channels are independent of each other. With the enhancement of channel spatial correlation, MIMO communication The bit error rate increases and the data transmission rate decreases; the smart antenna uses adaptive beamforming technology to make the main beam direction point to the signal direction and suppress interference in other directions, so the spatial correlation of the channel is strong, especially in the line-of-sight In the case of (Line of Sight), it tends to the best algorithm, and as the channel spatial correlation weakens, the bit error rate of smart antenna communication increases and the data transmission rate decreases.

However, the state of the wireless channel is time-varying. Due to the movement of the mobile station and the obstruction of buildings, the spatial correlation of the channel varies greatly at different times. Currently known literature, patents and related publications do not provide a more effective multi-antenna communication method for changes in the spatial correlation of actual channels. We combine the existing MIMO technology and smart antenna technology, and propose a multi-antenna communication method adaptively adjusted according to the channel spatial correlation, which can overcome the error caused by the single multi-antenna communication method when the channel spatial correlation changes. The drawbacks of increasing the rate and decreasing the data transmission rate make it possible to maintain a high data transmission rate and good communication quality under different channel conditions.

Contents of the invention

In view of the problem that the existing multi-antenna transmission scheme cannot continue to perform high-speed and high-quality communication under the condition that the channel spatial correlation changes, the purpose of the present invention is to provide a multi-antenna communication method adaptively adjusted according to the channel spatial correlation, Its advantage is that it can adopt different multi-antenna transmission schemes according to the change of channel spatial correlation. Compared with the multi-antenna communication method of a single transmission mode, the present invention is more able to adapt to changing wireless channel environments, and can maintain a higher data transmission rate and better communication quality under the condition of channel changes.

As shown in Figure 4, a kind of multi-antenna communication method according to channel spatial correlation adaptive adjustment provided by the present invention is characterized in that it comprises the following steps:

Step 1: Send control signaling and detect channel status information

At the beginning of communication, the control channel is turned on, and the base station and the mobile station send space-time coded control signaling to obtain channel state information at the receiving end, and calculate the channel spatial correlation coefficient ρ at this time.

Step 2: Communication initial transmission scheme selection

Compare the channel spatial correlation coefficient ρ obtained in step 1 with the threshold value ρ ₀ , if ρ≥ρ ₀ , it indicates that the spatial correlation of the channel is strong at this time, and the smart antenna scheme is selected to transmit business information; if ρ<ρ ₀ , It shows that the spatial correlation of the channel is weak at this time, and the V-BLAST scheme is selected to transmit service information, and at the same time, the sender and receiver are notified to switch the transmission and reception schemes through control signaling, and then the control channel is closed.

Step 3: Business Information Transmission

The business information is transmitted according to the selected transmission scheme.

Step 4: Monitor Channel Changes

During the transmission of the service information in step 3, channel changes are monitored simultaneously, and the channel spatial correlation coefficient ρ is obtained by measurement.

Step 5: Switch the transmission scheme during the communication, and coordinate the communication parties

Comparing the channel spatial correlation coefficient ρ obtained in step 4 with the threshold value _ρ0 , if the handover condition is not met, keep the current transmission scheme unchanged, and proceed to step 3 and step 4; if the handover condition is met, the base station starts Control channel, send control information to the mobile station, request the mobile station to change the transmission mode and retransmit the lost data packet through the traffic channel, the control information should include the starting frame number of the lost mobile station data packet. After the mobile station receives the control signaling requiring handover, it switches the transmission mode of the service information, and sends a feedback signal of the handover completion to the base station through the control channel. The feedback signal should include the starting frame number of the lost base station data packet. After receiving the feedback signal, close the control channel, and transmit the service information from the service channel in the selected transmission mode, and go to step 3 and step 4.

It should be noted:

The space-time coding method of the control signaling in step 1 adopts a coding method that is less affected by channel spatial correlation, such as space-time block codes.

The channel state information in step 1 can be obtained through channel estimation or other measurement methods;

The threshold value _ρ0 in step 2 is determined by the specific system parameters in the project, such as the number of transmitting and receiving antennas, multi-antenna detection algorithm and modulation mode, etc. The selection of _ρ0 should also take into account the time required for handover, and ensure that Communication cannot be interrupted during this period;

The channel spatial correlation coefficient ρ in step 4 can be obtained through channel estimation or other measurement methods.

Main principle of the present invention and basis:

1. The spatial correlation of the channel is used as the judgment basis for switching the transmission scheme. When the channel spatial correlation is strong, the smart antenna scheme is used for transmission, and when the channel spatial correlation is weak, the V-BLAST scheme is used for transmission.

Due to the high spectrum utilization of V-BLAST technology and simple decoding, its performance improves with the weakening of channel spatial correlation, while the spectrum utilization of smart antenna technology is high, and its performance increases with the enhancement of channel spatial correlation. And improve. In the present invention, the V-BLAST scheme is used to transmit service information when the spatial correlation of the channel is weak (such as channel independence), and the smart antenna scheme is used to transmit the business information when the spatial correlation of the channel is strong (such as line-of-sight). business information. The selection of V-BLAST and smart antenna transmission schemes at the beginning of communication and the switching between V-BLAST and smart antenna transmission schemes during communication are determined by the spatial correlation of the channel. When the measured spatial correlation coefficient ρ of the channel for a certain period of time is greater than or equal to the threshold value ρ ₀ , the transmission mode of the service information is switched to the smart antenna scheme (ρ ₀ is determined by the specific system parameters in the project, such as the number of transmitting and receiving antennas, how many Antenna detection algorithm and modulation mode, etc. The selection of _ρ0 should also take into account the time required for switching, and ensure that communication cannot be interrupted during the switching period); when ρ is less than _ρ0 , the transmission mode of business information is switched to the smart antenna scheme.

2. Control signaling and service information are transmitted using different transmission schemes

The control signaling is used to measure the current channel spatial correlation by sending the control signaling at the beginning of the communication because the channel situation is unknown; The signaling notifies both parties of the communication of the data frame to be retransmitted and the change of the transmission scheme. Therefore, the control signaling needs to select a space-time code that is less affected by channel spatial correlation for transmission, so as to ensure reliable communication and smooth switching of service information transmission modes; The spectrum utilization rate of its transmission mode is not high. Service information is used to transmit data that needs to be communicated, so it is necessary to adopt a transmission scheme with high spectrum utilization rate and low bit error rate for different channel environments to improve data transmission rate and communication quality.

A multi-antenna communication system adaptively adjusted according to channel space correlation constructed by the present invention includes a control signaling information transmitter, a control signaling information receiver, a service information transmitter and a service information receiver.

The structures of the control signaling information transmitter and the control signaling information receiver are shown in FIG. 5 . The control signaling information transmitter includes a space-time coding module 9, a digital-to-analog conversion module 10 (wherein the digital-to-analog conversion sub-modules corresponding to different transmitting antennas can be different), a radio frequency processing module 11 (wherein the corresponding radio frequency processing of different transmitting antennas 1 submodule can be different), M transmitting antennas. The control signaling information receiver includes N receiving antennas, a radio frequency processing 2 module 12 (wherein the radio frequency processing 2 submodules corresponding to different receiving antennas can be different), an analog-to-digital conversion module 13 (wherein different receiving antennas correspond to analog-to-digital conversion The submodules can be different), the space-time decoding module 14, and the synchronization channel estimation 1 module 15.

The working process of the transmitter and receiver of control signaling information is as follows:

At the transmitting end, the control signaling b _C (t) is input into the space-time coding module 9, and the information after space-time coding is input into the digital-to-analog conversion module 10 to be converted into an analog signal, and the analog signal is input into the radio frequency processing 1 module 11 and passed through M transmitting antennas emission. At the receiving end, N receiving antennas input the received signal into the radio frequency processing 2 module 12, and the output analog signal is converted into a digital signal by the analog-to-digital conversion module 13 and input into the space-time decoding module 14 and the synchronous channel estimation 1 module 15 respectively, The digital information output by the space-time decoding module 14 in conjunction with the analog-to-digital conversion module 13 and the synchronization and channel estimation information output by the synchronization channel estimation 1 module 15 obtain the estimated value of the control signaling

The structure of the transmitter and receiver of the service information is shown in Figure 6. The service information transmitter includes a transmission scheme selection module 16, an adaptive transmission beamforming module 23, a V-BLAST coding module 5, a digital-to-analog conversion module 10 (wherein the digital-to-analog conversion sub-modules corresponding to different transmitting antennas can be different), radio frequency processing 3 module 17 (wherein the radio frequency processing sub-modules corresponding to different transmitting antennas can be different), radio frequency processing module 20 (wherein the radio frequency processing sub-modules corresponding to different transmitting antennas can be different), the transmitting antenna array TX _SA of the smart antenna , V-BLAST transmit antenna array TX _BLAST . The service information receiver includes the receiving antenna array RX _SA of the smart antenna, the receiving antenna array RX _BLAST of V-BLAST, the radio frequency processing module 18 (the radio frequency processing sub-modules corresponding to different receiving antennas can be different), and the radio frequency processing module 6 21 (wherein the radio frequency processing 6 submodules corresponding to different receiving antennas can be different), the analog-to-digital conversion module 13 (wherein the analog-to-digital conversion submodules corresponding to different receiving antennas can be different), synchronous channel estimation 2 module 19, synchronous channel estimation 3 Module 22, adaptive receiving beamforming module 24, V-BLAST decoding module 6.

如果选择V-BLAST传输方案，则业务信息b_D(t)输入V-BLAST编码模块5，经过编码的信息输入数模转换模块10，输出的模拟信号输入射频处理4模块20后经过V-BLAST的发射天线阵TX_BLAST发射。在接收端，V-BLAST的接收天线阵RX_BLAST将接收到的信号输入射频处理6模块21，输出的模拟信号输入模数转换模块13得到数字信号并分别输入同步信道估计3模块22和V-BLAST译码模块6，V-BLAST译码模块6利用模数转换模块1 3输出的数字信号和同步信道估计3模块22输出的同步、信道估计信息，得到业务信息的估计值

The working process of the transmitter and receiver of business information is as follows: at the transmitting end, the transmission scheme selection module 16 selects the transmission scheme of business information according to the input channel spatial correlation coefficient ρ, if the smart antenna transmission scheme is selected, the business information b _D (t ) is input to the adaptive transmit beamforming module 23, the weighted information is input to the digital-to-analog conversion module 10, and the output analog signal is input to the radio frequency processing module 17 and then transmitted through the transmitting antenna array TX _SA of the smart antenna. At the receiving end, the receiving antenna array RX _SA of the smart antenna inputs the received signal into the radio frequency processing module 18, and the output analog signal is input into the analog-to-digital conversion module 13 to obtain a digital signal and input into the synchronous channel estimation module 19 and the adaptive channel estimation module 19 respectively. The receiving beamforming module 24, the adaptive receiving beamforming module 24 uses the digital signal output by the analog-to-digital conversion module 13 and the synchronization and channel estimation information output by the synchronization channel estimation 2 module 19 to obtain the estimated value of the service information

If the V-BLAST transmission scheme is selected, the business information b _D (t) is input to the V-BLAST encoding module 5, the encoded information is input to the digital-to-analog conversion module 10, and the output analog signal is input to the radio frequency processing module 20 and then passed through V-BLAST The transmit antenna array TX _BLAST transmits. At the receiving end, the receiving antenna array RX _BLAST of V-BLAST inputs the received signal into the radio frequency processing module 21, and the output analog signal is input into the analog-to-digital conversion module 13 to obtain a digital signal, which is respectively input into the synchronous channel estimation module 22 and V-BLAST The BLAST decoding module 6 and the V-BLAST decoding module 6 use the digital signal output by the analog-to-digital conversion module 13 and the synchronization and channel estimation information output by the synchronization channel estimation module 22 to obtain the estimated value of the service information

It should be noted:

The space-time code used for the control signaling information in Figure 5 is a space-time code that is less affected by channel spatial correlation, such as space-time block codes, etc.;

The channel spatial correlation coefficient ρ in FIG. 6 is provided by control signaling at the beginning of communication, and is provided by channel information carried in service information during communication.

The adaptive transmit beamforming module 23 in FIG. 6 may use any adaptive beamforming algorithm capable of forming transmit beams, and the adaptive transmit beamforming module 24 may use any adaptive beamforming algorithm capable of forming receive beams.

Working process of the present invention:

At the beginning of the communication, the mobile station and the base station use the control channel to transmit signaling information using the space-time coding scheme with less channel spatial correlation, and measure the current channel correlation coefficient ρ: If the channel correlation coefficient between the mobile station and the base station ρ is greater than or equal to the threshold value ρ ₀ , the traffic channel uses the smart antenna scheme to start the transmission of business information, and at the same time closes the control channel; if the channel correlation coefficient ρ between the mobile station and the base station is less than the threshold value ρ ₀ , the traffic channel Use the V-BLAST scheme to start the transmission of service information, and close the control channel at the same time.

During the communication process, due to the change of the position of the mobile station, the channel correlation may change at any time. If the spatial correlation coefficient ρ of the channel between the mobile station and the base station is greater than or equal to the threshold value ρ ₀ , the base station opens the control channel and sends control information to the mobile station, requiring the mobile station to change the codec mode and retransmit the lost data through the traffic channel. In the data packet, the control information shall contain the starting frame number of the lost mobile station data packet. After the mobile station receives the control signaling requiring handover, it switches the codec mode of the service information, and sends a feedback signal of handover completion to the base station through the control channel. The feedback signal should include the starting frame number of the lost base station data packet. After receiving the feedback signal, the base station closes the control channel, and transmits the service information through the service channel using the smart antenna transmission scheme.

If the correlation coefficient ρ of the channel between the mobile station and the base station is less than the threshold value ρ ₀ , the base station opens the control channel and sends control information to the mobile station, requiring the mobile station to change the encoding and decoding mode and retransmit data packets with serious bit errors. The information shall include the starting frame number of the mobile station data packet to be retransmitted. After the mobile station receives the control signaling requiring switching, it switches the codec mode of the service information, and sends a feedback signal of switching completion to the base station through the control channel. The feedback signal should include the starting frame number of the base station data packet that needs to be retransmitted . After receiving the feedback signal, the base station closes the control channel, encodes the service information with V-BLAST, and transmits it through the service channel.

The innovation of the present invention is that the existing multi-antenna communication methods are all based on a single transmission mode, and when the channel spatial correlation changes, the data rate decreases and the communication quality deteriorates. The present invention provides a multi-antenna communication method adaptively adjusted according to channel spatial correlation, which can adaptively adopt different multi-antenna transmission schemes in response to changes in channel spatial correlation, so that it can maintain a relatively high frequency in the case of channel changes. High communication transmission rate and better communication quality.

Beneficial effects of the present invention:

1. Solved the problem of data transmission rate drop and communication quality degradation caused by the change of channel spatial correlation in a single multi-antenna transmission method. Different signal transmission methods are used for different channel conditions, which makes the channel spatial correlation change Under all circumstances, the communication can maintain a high transmission rate and a good communication quality.

2. The spatial correlation of the channel is used as the basis for the switching of the transmission mode, which can sensitively reflect the change of the channel and ensure the accuracy and timeliness of the switching of the transmission mode.

3. Different encoding methods are used for control information and business information, which can realize the effective transmission of control information all the time and achieve the purpose of controlling the transmission of business information, thereby improving the reliability of the system.

Description of drawings

Figure 1 is a schematic diagram of a space-time block code transmitter

Among them, 1 is the transmitting data module, 2 is the space-time block coding module, 3 is the transmitting antenna, TX1 represents transmitting antenna 1, TX2 represents transmitting antenna 2, ${\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="C20051002153900142.png,C20051002153900161.png"\; state="\{\{state\}\}">c</figure-callout>}}^1=\left[\begin{array}{cc}{c}_1& -c_2^{*}\end{array}\right]$ represents the symbol transmitted on transmit antenna 1, $c^2=\left[\begin{array}{cc}{c}_2& {\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="C20051002153900142.png,C20051002153900161.png"\; state="\{\{state\}\}">c</figure-callout>}}_1^{*}\end{array}\right]$ Represents the symbol transmitted on transmit antenna 2.

Figure 2 is a schematic diagram of the V-BLAST system

Among them, 1 is the transmitting data module, 5 is the V-BLAST encoding module, 3 is the transmitting antenna, 4 is the receiving antenna, 6 is the V-BLAST decoding module, 7 is the recovery data module, TX1 represents the transmitting antenna 1, and TXk represents the transmitting Antenna k, TXM represents transmitting antenna M, RX1 represents receiving antenna 1, RXk represents receiving antenna k, and RXN represents receiving antenna N.

Figure 3 is a schematic diagram of the principle of the smart antenna

Among them, 8 is an adaptive beamforming module.

Fig. 4 is a schematic diagram of the workflow of the present invention

Among them, ρ represents the channel spatial correlation coefficient, and ρ ₀ represents the threshold value.

Fig. 5 is a schematic diagram of a transmitter and a receiver of control signaling information in the present invention

代表恢复的控制信令信息。Among them, 9 is a space-time encoding module, 10 is a digital-to-analog conversion module, 11 is a radio frequency processing 1 module, 12 is a radio frequency processing 2 module, 13 is an analog-to-digital conversion module, 14 is a space-time decoding module, and 15 is synchronization and channel estimation 1 module, 3 is the transmitting antenna, 4 is the receiving antenna, TX1 represents the transmitting antenna 1, TXM represents the transmitting antenna M, RX1 represents the receiving antenna 1, RXN represents the receiving antenna N, b _C (t) represents the control signaling information,

Represents restored control signaling information.

Fig. 6 is a schematic diagram of a transmitter and a receiver of service information in the present invention

代表恢复的业务信息，TX_SA代表智能天线的发射天线阵，RX_SA代表智能天线的接收天线阵，TX_BLAST代表V-BLAST的发射天线阵，RX_BLAST代表V-BLAST的接收天线阵。Among them, 16 is a transmission scheme selection module, 23 is an adaptive transmit beamforming module, 10 is a digital-to-analog conversion module, 17 is a radio frequency processing 3 module, 18 is a radio frequency processing 5 module, 13 is an analog-to-digital conversion module, and 19 is a synchronization channel Estimation 2 module, 24 is adaptive receiving beamforming module, 5 is V-BLAST coding module, 20 is RF processing 4 module, 21 is RF processing 6 module, 22 is synchronous channel estimation 3 module, 6 is V-BLAST decoding module, b _D (t) represents business information,

Represents the restored service information, TX _SA represents the transmitting antenna array of the smart antenna, RX _SA represents the receiving antenna array of the smart antenna, TX _BLAST represents the transmitting antenna array of V-BLAST, and RX _BLAST represents the receiving antenna array of V-BLAST.

Detailed ways:

波长。A specific embodiment of the present invention is given below. The space-time coding and decoding of control signaling information adopts STBC codes which are less affected by channel spatial correlation changes. In the transmission of service information, both the adaptive transmit beamforming and the adaptive receive beamforming of the transmission scheme of the smart antenna adopt an algorithm based on the minimum mean square error criterion. The detection algorithm of V-BLAST adopts the interference cancellation algorithm based on the minimum mean square error criterion (MMSE-SIC). The number of antennas at the base station is 8, which are divided into two groups with 4 antennas in each group. The spacing between each antenna of the first group wavelength, the second set of 10 times the wavelength of the spacing between each antenna. The first group is used as the base station antenna of the smart antenna, the second group is used as the base station antenna of V-BLAST, and the two antennas of the second group are selected as the base station antenna of STBC. The number of mobile station antennas is 4, and the interval is

wavelength.

The transmission of control signaling information adopts the STBC code of 2 transmissions and 2 receptions, and the transmission of business information adopts the V-BLAST algorithm of 4 transmissions and 4 receptions and the smart antenna algorithm of 4 transmissions and 4 receptions, all based on QPSK modulation. The threshold value of transmission scheme switching is selected as ρ ₀ =0.6.

Based on the above system parameters, the working steps of the present invention are as follows:

Step 1: Send control signaling and detect channel status information

At the beginning of the communication, the control channel is turned on, and the base station and the mobile station send STBC-coded control signaling, and the receiving end obtains channel state information through STBC channel estimation, and calculates the channel spatial correlation coefficient ρ at this time.

Step 2: Communication initial transmission scheme selection

Compare the channel spatial correlation coefficient ρ obtained in step 1 with the threshold value ρ ₀ =0.6, if ρ≥ρ ₀ , it indicates that the channel has a strong spatial correlation at this time, and the traffic channel adopts 4 transmissions and 4 receptions, based on the minimum average The smart antenna scheme of the beamforming algorithm based on the square error criterion starts to transmit service information; if ρ<ρ ₀ , it means that the spatial correlation of the channel is weak at this time, and the service channel adopts 4 transmissions and 4 receptions, based on MMSE-SIC detection The V-BLAST scheme starts to transmit service information, and at the same time notifies the sending and receiving parties to switch the transmitting and receiving schemes through control signaling, and then closes the control channel.

Step 3: Business Information Transmission

The business information is transmitted according to the selected transmission scheme.

Step 4: Monitor Channel Changes

During the transmission of service information in step 3, channel changes are monitored simultaneously, and the channel spatial correlation coefficient ρ is obtained through channel estimation and measurement.

Step 5: Switch the transmission scheme during the communication, and coordinate the communication parties

Compare the channel spatial correlation coefficient ρ obtained in step 4 with the threshold value ρ ₀ =0.6, if the switching condition is not satisfied, keep the current transmission scheme unchanged, and proceed to step 3 and step 4; if the switching condition is satisfied, then The base station opens the control channel, sends STBC-coded control information to the mobile station, and requires the mobile station to change the transmission mode and retransmit the lost data packet through the traffic channel. The control information should include the starting frame number of the lost mobile station data packet. After the mobile station receives the control signaling requiring handover, it switches the transmission mode of the service information, and sends a feedback signal of the handover completion to the base station through the control channel. The feedback signal should include the starting frame number of the lost base station data packet. After receiving the feedback signal, close the control channel, and transmit the service information from the service channel in the selected transmission mode, and go to step 3 and step 4.

The specific implementation manner of the present invention can be realized through software programming, and can also be realized through hardware.

To sum up, the present invention provides a multi-antenna communication method adaptively adjusted according to channel spatial correlation. By measuring the spatial correlation coefficient of the channel, different multi-antenna transmission schemes are adaptively used for information transmission. Compared with the general multi-antenna transmission scheme, it can maintain a higher communication transmission rate and better communication quality in the case of channel changes.

Claims (4)

1. according to the multi-antenna communication method of adaptive adjustment of channel space correlation, it is characterized in that, it comprises the following steps: Step 1: Send control signaling and detect channel status information At the beginning of the communication, the control channel is turned on, and the base station and the mobile station send the control signaling through space-time coding to obtain the channel state information at the receiving end, and calculate the channel spatial correlation coefficient ρ at this time; Step 2: Communication initial transmission scheme selection Compare the channel spatial correlation coefficient ρ obtained in step 1 with the threshold value ρ ₀ , if ρ≥ρ ₀ , it indicates that the spatial correlation of the channel is strong at this time, and the smart antenna scheme is selected to transmit business information; if ρ<ρ ₀ , It shows that the spatial correlation of the channel is weak at this time, and the V-BLAST scheme is selected to transmit business information, and at the same time, the sender and receiver are notified to switch the transmission and reception schemes through control signaling, and then the control channel is closed; Step 3: Business Information Transmission Transmit business information according to the selected transmission plan; Step 4: Monitor Channel Changes During the transmission of the service information in step 3, channel changes are simultaneously monitored, and the channel spatial correlation coefficient ρ is obtained by measurement; Step 5: Switch the transmission scheme during the communication, and coordinate the communication parties Comparing the channel spatial correlation coefficient ρ obtained in step 4 with the threshold value _ρ0 , if the handover condition is not met, keep the current transmission scheme unchanged, and proceed to step 3 and step 4; if the handover condition is met, the base station starts Control channel, send control information to the mobile station, request the mobile station to change the transmission scheme and retransmit the lost data packet through the traffic channel, the control information should include the starting frame number of the lost mobile station data packet; the mobile station receives the request to switch After the control signaling, the transmission scheme of the service information is switched, and the feedback signal of the switching completion is sent to the base station through the control channel. The feedback signal should include the starting frame number of the lost base station data packet. After the base station receives the feedback signal, Close the control channel, and transmit the service information from the service channel with the selected transmission scheme, go to step 3 and step 4. 2. The multi-antenna communication method for adaptive adjustment according to channel spatial correlation according to claim 1, wherein the control signaling and business information adopt different transmission schemes, and the business information in step 3 adopts smart antenna technology or In the V-BLAST technology, the space-time coding method of the control signaling in step 1, step 2 and step 5 adopts a space-time block coding method that is less affected by channel spatial correlation. 3. the multi-antenna communication method according to channel spatial correlation self-adaptive adjustment according to claim 1, is characterized in that, the threshold value ρ in the step 2 and the step ₅ is by the transmitting and receiving antenna in the project, multi-antenna detection algorithm The specific system parameters are determined by the three aspects of modulation and modulation mode. The choice of _ρ0 should also take into account the time required for switching, and ensure that the communication cannot be interrupted during the switching period. 4. The multi-antenna communication method for adaptive adjustment according to channel spatial correlation according to claim 1, characterized in that the channel spatial correlation coefficient ρ in step 4 is obtained through channel estimation.

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