CN100358258C - Combined delay space emission diversity scheme in CDMA system - Google Patents

Abstract

The present invention relates to a combined delay space emission diversity scheme in a CDMA system, which is a solving scheme of space emission diversity in a multiple-input and multiple-output CDMA system and is mainly used for solving the problems of low coding efficiency and resistance fast fading multipath channels when a traditional method of emission diversity of space block codes is adopted in an MIMO CDMA system. The combined delay space emission diversity scheme in a CDMA system adopts a space emission diversity method, namely after information symbols in grouping respectively adopt different orthogonal spread spectrum codes for spreading a spectrum, the information symbols are superimposed together; then, different symbol periods are respectively delayed through different antennae for emitting the symbols. The combined delay space emission diversity scheme in a CDMA system is suitable for the number of any signal and any emission antennae.

Description

Joint Delay Space-Time Transmit Diversity Method in Code Division Multiple Access System

technical field

The present invention is a solution for space-time transmit diversity in MIMO CDMA (Multiple Input Multiple Output, Code Division Multiple Access) system. It is mainly used to solve the problem of low coding efficiency and countering fast fading multipath channels when traditional space-time block code transmit diversity method is adopted in MIMO CDMA system, and belongs to the technical field of space-time transmit diversity of MIMO CDMA system.

Background technique

There are many unfavorable factors in the wireless channel environment, such as multipath fading, Doppler frequency shift, and fast time-varying channels. How to overcome this unfavorable factor is always a problem that needs to be studied in mobile communication. At present, in order to ensure the reliable transmission of wireless channels, many technologies have been proposed. From the perspective of information theory, it has been proved that MIMO technology can greatly increase the capacity of wireless communication systems and improve the performance of wireless communication systems. MIMO technology is a major breakthrough in the field of wireless mobile communication. It utilizes the increased transmission channel in the space, and uses multiple antennas at the transmitting end and the receiving end. Since the signals transmitted by each transmitting antenna simultaneously occupy the same frequency band, the bandwidth is not increased. Therefore, the system capacity and spectrum utilization can be greatly improved.

In a broad sense, MIMO technology involves a wide range, mainly including transmit diversity technology and space multiplexing technology. Among them, spatial multiplexing technology is to transmit different information on different antennas. The V-BLAST code of Bell Labs is a typical application of spatial multiplexing technology; while transmit diversity technology is to transmit signals containing the same information on different antennas. So as to achieve the effect of space diversity. Space-time coding technology based on transmit diversity has attracted much attention because it combines transmit diversity in the space domain and coding in the time domain, which can largely overcome channel fading and improve system performance.

Space-Time-Coding (Space-Time-Coding) technology is a technology based on transmit diversity proposed by Tarokh et al. in 1998. Tarokh et al. believe that if a coding technology suitable for multi-antenna transmission is adopted at the transmitting end, and corresponding signal processing technology is performed at the receiving end, a large performance gain can be obtained. Research on information theory shows that assuming that the multi-antenna system has M transmitting antennas and N receiving antennas, and assuming a narrow-band slow fading channel, an M×N order matrix reflecting channel characteristics can be established, and its elements are independent and identically distributed Gaussian In this way, the available channel capacity of the system will be min(M, N) times higher than that of a single antenna, and the total transmission power will remain unchanged. However, since the instantaneous information of the fading channel is difficult to capture, the transmitter must use channel coding technology to ensure better performance in most channel situations. This channel coding is essentially two-dimensional in time and space. Coding, that is, space-time coding.

There are two main types of space-time coding based on transmit diversity: space-time block code (STBC, Space Time BlockCode) and space-time trellis code (STTC, Space Time Trellis Code). The space-time trellis code was proposed by Tarokh et al. in 1998. The space-time trellis code combines coding, modulation, and transmit diversity, which can obtain diversity gain and coding gain at the same time, and greatly improve the performance of the system. However, Because it uses Viterbi decoding based on Euclidean distance, the decoding complexity is relatively high, and the decoding complexity will increase exponentially with the increase of the transmission rate. The space-time block code was proposed by Alamouti in 1998. The space-time block code is to transmit the same information from two antennas after orthogonal coding. Due to the orthogonality of the two signals, it only needs to be simple at the receiving end. Gains can be obtained by combining linearly. Space-time block codes have been widely studied due to their simple structure and good performance, and soon entered 3GPP. However, there are still some problems in the construction of space-time block codes. For complex signals, whether there is a code group with a coding rate of 1 when the number of transmission days is greater than 2 remains to be further studied, and the space-time block code transmit diversity scheme is only applicable in quasi-static fading channels.

Contents of the invention

Technical problem: The purpose of the present invention is to provide a joint delay space-time transmit diversity method in MIMO and CDMA systems, which is used to solve the problem of coding efficiency when the number of transmission days is greater than 2 in traditional space-time block code transmit diversity. Not high disadvantage, and can effectively resist fast fading multipath channel.

Technical solution: The technical feature of the present invention is a method for joint delay space-time transmit diversity.

The joint delay space-time transmit diversity scheme in the code division multiple access system adopts the space-time transmit diversity method. The information symbols in the group are spread by different orthogonal spreading codes and superimposed together, and then separated by different antennas. The transmission is delayed by different symbol periods. The specific method is:

The transmitting end is equipped with M transmitting antennas:

1), first group the input information, each group contains M symbols, b ₁ , b ₂ ...b _m ...b _M ,

2), multiplying each information symbol in the group by a spreading code and superimposing them to form combined information,

3), each transmit antenna delays the corresponding symbol period and transmits the combination information, and the mth transmit antenna delays m-1 symbol period;

The receiving end is equipped with N receiving antennas:

21), first collect the received information of M symbol periods,

22), forming a code array with the information received in these M symbol periods,

23), constructing an equivalent channel matrix using channel information and M spreading codes adopted during transmission,

24), using the equivalent channel matrix to linearly combine the received information,

25), sum the information on all receiving antennas after the same processing,

26). Finally, a decision is made on the summed information, and the transmission information is resumed.

One of the design criteria of space-time block codes is orthogonal design, that is, the space-time block code matrix satisfies the orthogonality. However, for complex signals and the number of transmitting antennas is greater than 2, there is no such code matrix that satisfies the orthogonality condition so that The coding efficiency is 1; in addition, there is a restriction on the decoding of space-time block codes, that is, under the quasi-static channel, that is, the channel does not change within a code group, which is difficult to satisfy in practical applications.

This method is a joint delay space-time transmit diversity in a MIMO CDMA system. It groups the input information symbols, and the symbols in each group are spread by different orthogonal spreading codes and superimposed together, and then passed through different The antennas are respectively delayed by different symbol periods to transmit. This joint-delay space-time transmit diversity scheme is suitable for any signal and any number of transmit antennas, and it can effectively combat fast fading multipath channels.

Beneficial effect: using this method has the following advantages:

1. It overcomes the shortcoming of low coding efficiency for complex signals when the number of transmit antennas is greater than 2 in the space-time block code transmit diversity scheme, and this scheme is applicable to any signal and any number of transmit antennas.

2. This scheme can effectively fight against fast-fading multipath channels, while the space-time block code transmit diversity scheme is only suitable for quasi-static fading channels.

Description of drawings

Figure 1 is a comparison of bit error performance between the space-time block code transmit diversity method and the joint delay space-time transmit diversity scheme in a single-path fading channel environment.

Fig. 2 is a bit error performance comparison between the space-time block code transmit diversity method and the joint delay space-time transmit diversity scheme in a four-path fading channel environment. In the figure, STBC represents a space-time block code transmit diversity scheme; UD-STTD represents a joint delay space-time transmit diversity scheme.

Fig. 3 is a block diagram of steps in which the transmitting end is provided with M transmitting antennas.

Fig. 4 is a block diagram of steps in which the receiving end is provided with N receiving antennas.

Detailed ways

Joint Delay Space-Time Transmit Diversity (UD-STTD) Method

For a MIMO CDMA system with M transmit antennas and N receive antennas, the input information symbols are grouped first, and each group contains M symbols (b ₁ , b _z ...b _m ...b _M ), where b _M represents the information symbol vector , b _m represents the information symbol. The M symbols are respectively spread by using different orthogonal spreading codes and superimposed together, and then transmitted through different antennas with different symbol periods delay. The transmitted code array is as follows (taking two transmitting antennas as an example, the row represents the number of transmitting antennas, and the column represents the number of symbol periods):

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="B"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">B</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}& \\ & {\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}\end{array}\right]<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

in $c_m=1/\sqrt{Q}[c_{m,1},c_{m,2},\&CenterDot;\&CenterDot;\&CenterDot;c_{m,q}\&Center\; Dot;\&Center\; Dot;\&CenterDot;c_{m,Q}]$ Indicates the spreading code of the mth symbol, c _m,q =±1, Q is the spreading gain, B ₂ is the combined information matrix, and T is the transpose.

The received signal in M symbol periods on the nth receiving antenna can be expressed as

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="T\; B"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">T</figure-callout></span><figure-callout\; id="2"\; label="T\; B"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">\; </figure-callout>}}{\mathrm{<span\; class="notranslate">\; </span>}}_{}{\mathrm{<span\; class="notranslate">B</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>{\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="T\; h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">T</figure-callout></span><figure-callout\; id="2"\; label="T\; h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">\; </figure-callout>}}& \\ {\mathrm{<span\; class="notranslate">\; </span>}}_{}{\mathrm{<span\; class="notranslate">h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}\end{array}\right]}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<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>$

$<span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}$

Where h _2,n =[h _1,n ,h _2,,n ] ^T represents a channel vector, and h _m,n represents a channel parameter between the mth transmitting antenna and the nth receiving antenna. ξ _n is a Gaussian white noise vector with variance σ ² I, r _{n, m} represents one of r _n,1 and r _n,2, and represents the received signal of the nth receiving antenna in the mth symbol period. Assuming that the channel parameter vector h _{2, n} = [h _{1, n} , h _{2, n} ] ^T has been estimated, construct an equivalent channel vector $G_{}$${}_{2,\mathrm{no}}=\left[\begin{array}{cc}{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout>}}_{1,\mathrm{no}}{c}_1& {\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout>}}_{2,\mathrm{no}}{c}_1\\ {\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout>}}_{1,\mathrm{no}}{c}_2& {\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout>}}_{2,\mathrm{no}}{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">c</figure-callout>}}_2\end{array}\right],$ Then the original emission information can be solved as

表示b₂＝[b₁，b₂]的估计，H表示共轭转置。对于N根接收天线，则in

Denotes the estimate of b ₂ =[b ₁ , b ₂ ], and H denotes the conjugate transpose. For N receiving antennas, then

Where Dec(.) represents a judgment.

Comparison of Joint Delayed Space-Time Transmit Diversity and Space-Time Block Codes for Transmitting Codewords in MIMO CDMA Systems

Table 1 shows the comparison between the joint delay space-time transmit diversity scheme (UD-STTD) and the space-time block code transmit diversity scheme (STBC) in transmitting signals within two symbol periods (number of transmit antennas M=2).

Table 1

Simulation comparison

The space-time block code transmit diversity scheme and the joint delay space-time transmit diversity scheme are simulated and compared in the same environment under the MIMO CDMA system. Assume that the number of users is K=4, the signal source is 2PSK signal, the spreading code adopts 32-bit Walsh code, the multiple access interference MAI=10dB, and the channels adopt single-path Rayleigh fading channel and four-path Rayleigh fading channel respectively, and four-path Rayleigh When the channel is fading, the delay of each path differs by one chip period and the fading amplitude of each path differs by 4dB.

The simulation results are shown in Figure 1 and Figure 2 (the bit error rate in the figure is obtained after receiving 5000 symbols and taking the average).

Figure 1 is a comparison of bit error performance in a single-path fading channel environment. It can be seen from the figure that the bit error performance of the two schemes is relatively close no matter in the case of two transmissions and one reception or two transmissions and two receptions. Figure 2 is a comparison of bit error performance in a four-path fading channel environment. It can be seen from the figure that no matter in the case of two transmissions and one reception or two transmissions and two receptions, the joint delay space-time transmit diversity scheme is better than the space-time block code The bit error performance of the transmit diversity scheme is good, which shows that the joint delay space-time transmit diversity scheme has a strong ability to resist multipath fading.

Specific steps:

1. Transmitting end (assuming there are M transmitting antennas)

1. First, group the input information, and each group contains M symbols (b ₁ , b ₂ ...b _m ...b _M ).

2. Each grouped information symbol is multiplied by a spreading code and superimposed to form combined information. (Take two transmitting antennas as an example)

b ₁ c ₁ ^T +b ₂ c ₂ ^T

3. Each transmit antenna delays the corresponding symbol period and transmits the combined information (the mth transmit antenna delays m-1 symbol period)

The transmitted code array is as follows (the row represents the number of transmitting antennas, and the column represents the number of symbol periods):

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="B"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">B</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}& \\ & {\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}\end{array}\right]$

in $c_m=1/\sqrt{Q}[c_{m,1},c_{m,2},\&CenterDot;\&Center\; Dot;\&Center\; Dot;c_{m,q}\&Center\; Dot;\&Center\; Dot;\&CenterDot;c_{m,Q}]$ represents the spreading code of the mth symbol, c _m,q =±1, and Q is the spreading gain.

2. The receiving end (N is the number of receiving antennas, still taking 2 transmitting antennas as an example)

1. Firstly, receiving information of M symbol periods is collected.

2. Combining the information received in these M symbol periods into a code array, assuming that h _{2, n} = [h _{1, n} , h _{2, n} ] ^T is the channel parameter from the 2 transmitting antennas to the nth receiving antenna vector, where h _{m, n} represent the channel parameters between the mth transmitting antenna and the nth receiving antenna, then the received signal on the nth receiving antenna within 2 symbol periods can be expressed as (assuming that the synchronization mechanism is perfect and there is no ISI and ICI)

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="T\; B"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">T</figure-callout></span><figure-callout\; id="2"\; label="T\; B"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">\; </figure-callout>}}{\mathrm{<span\; class="notranslate">\; </span>}}_{}{\mathrm{<span\; class="notranslate">B</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>{\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="T\; h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">T</figure-callout></span><figure-callout\; id="2"\; label="T\; h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">\; </figure-callout>}}& \\ {\mathrm{<span\; class="notranslate">\; </span>}}_{}{\mathrm{<span\; class="notranslate">h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}\end{array}\right]}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}$

$<span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}$

where ξ _n is a Gaussian white noise vector with variance σ ² I

3. Construct an equivalent channel matrix by using the channel information and the M spreading codes used during transmission.

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="G"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">G</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}& {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}& {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="h"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">h</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="c"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">c</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}\end{array}\right]$

4. Use the equivalent channel matrix to linearly combine the received information

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="G"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">G</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="b"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">b</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="G"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">G</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}$

5. Perform the same processing on the information on all receiving antennas and then sum them

$\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="G"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">G</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="1"\; label="b"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">b</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="G"\; filenames="C20051009538800101.png"\; state="\{\{state\}\}">G</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}^{\mathrm{<span\; class="notranslate">\; h</span>}}$

6. Finally, make a judgment on the summed information and resume transmitting information

Where Dec(.) represents a judgment.

Claims (1)

1. A joint delay space-time transmit diversity method in a code division multiple access system is characterized in that the space-time transmit diversity method is adopted, and the information symbols in the grouping are respectively superimposed after being spread by different orthogonal spreading codes , and then transmit them with different symbol periods delayed by different antennas; the specific method is: The transmitting end is equipped with M transmitting antennas: 1), first group the input information, each group contains M symbols, b ₁ , b ₂ ...b _m ...b _M , 2), multiplying each information symbol in the group by a spreading code and superimposing them to form combined information, 3), each transmit antenna delays the corresponding symbol period and transmits the combination information, and the mth transmit antenna delays m-1 symbol period; The receiving end is equipped with N receiving antennas: 21), first collect the received information of M symbol periods, 22), forming a code array with the information received in these M symbol periods, 23), constructing an equivalent channel matrix using channel information and M spreading codes adopted during transmission, 24), using the equivalent channel matrix to linearly combine the received information, 25), sum the information on all receiving antennas after the same processing, 26). Finally, a decision is made on the summed information, and the transmission information is resumed.

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