CN101163121B - Communication system and character code selection method thereof - Google Patents

Abstract

The present invention provides a codeword selection method. The codeword selection method is applicable to a multi-input multi-output communication system. The method comprises the following steps. First, a transmitter provides a complex code form. Then, a receiver receives the codeword form and calculates or looks up a table to obtain a corresponding bit error rate (BER) for each codeword form according to a decoding method. Next, the receiver selects a group codeword format with a minimum bit error rate and transmits it back to the transmitter. Finally, the transmitter determines the group codeword used for data transmission based on the codeword form with the minimum bit error rate.

Description

Communication system and character code selection method thereof

technical field

The present invention relates to a kind of multi-input multi-output communication system and its space-time word code (space-time (ST) codeword) selection method, particularly relate to a kind of use group type space-time block code (grouped space-time block code) , G-STBC) encoding method design, and the group-wise ST codeword (group-wise ST codeword) selection method and related systems under limited return information.

Background technique

Wireless communication systems require more and more data flow, so how to do efficient coding, modulation and signal processing to improve the quality and performance of wireless communication is a topic that is eager to be solved in research. In order to effectively improve the data transmission rate and communication link quality, more and more wireless communication systems adopt multiple-input multiple-output (MIMO) multi-antenna system design, that is, multiple antennas are used at the transmitting end and receiving end to realize Strong quality of service requirements for next-generation wireless communication systems. The coding of the multi-antenna system generally adopts space-time code (space-time code, STC). This coding is a transmission design across time and space, using the relationship between the transmission antenna and the transmission time to achieve the maximum diversity (full diversity), and even provide coding gain (coding gain). The main operation modes of space-time code can be divided into spatial diversity (spatial diversity, SD) and spatial multitasking (spatial multiplexing, SM). High link quality can be achieved by transmitting redundant signals on different transmit antennas in a spatially diverse manner, such as space-time block code (space-time block code, STBC) and space-time trellis code (ST trellis code, STTC). High spectral efficiency can be obtained by simultaneously transmitting different data on different transmitting antennas through spatial multitasking, such as multi-level space-time code (layered STC, LSTC) or the well-known Bell Labs layered ST (BLAST) technology.

FIG. 1 is a schematic diagram of a conventional space-time block coding system. Obviously, two transmitted symbols span space and time (space-time code). FIG. 2 shows another existing coding technique combining Q=2Alamouti's space-time code at the transmitting end, which is called double space-time transmit diversity (DSTTD) technique. Its space-time character code is

$\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; :</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>\frac{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 1,1</span>}}& <span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="S"\; filenames="H061D1798920061020E000072.png,H061D1798920061020E000091.png"\; state="\{\{state\}\}">S</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 1,2</span>}}^{<span\; class="notranslate">\; *</span>}\\ {\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 1,2</span>}}& {\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; 1,1</span>}}^{<span\; class="notranslate">\; *</span>}\end{array}}{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="S"\; filenames="H061D1798920061020E000072.png,H061D1798920061020E000091.png"\; state="\{\{state\}\}">S</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2,1</span>}}& {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="S"\; filenames="H061D1798920061020E000072.png,H061D1798920061020E000091.png"\; state="\{\{state\}\}"><figure-callout\; id="2"\; label="S"\; filenames="H061D1798920061020E000072.png,H061D1798920061020E000091.png"\; state="\{\{state\}\}">S</figure-callout></figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2,2</span>}}^{<span\; class="notranslate">\; *</span>}\\ {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="S"\; filenames="H061D1798920061020E000072.png,H061D1798920061020E000091.png"\; state="\{\{state\}\}">S</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2,2</span>}}& {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="S"\; filenames="H061D1798920061020E000072.png,H061D1798920061020E000091.png"\; state="\{\{state\}\}">S</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2,1</span>}}^{<span\; class="notranslate">\; *</span>}\end{array}}<span\; class="notranslate">\; ]</span>$

At this time, the coding rate is R=2, and the diversity gain of 2 can be obtained. However, although the coding method of this coding technology is relatively simple, its decoding method is more complex than STBC, and the character code structure suffers from many restrictions, making the coding design less flexible, and thus the performance is poor.

However, although spatial diversity can improve the quality of communication links, its spectrum utilization efficiency is low; on the contrary, although spatial multitasking can improve data transmission rate, its ability to resist channel fading is poor. Therefore, in order to obtain the maximum benefits, it is necessary to obtain an optimal profit and loss point between spatial diversity and spatial multitasking.

In addition, the calculation of the receiver must be as simple as possible to achieve fast decoding and also simplify the design of the receiver. Compared with the space-time code at the transmitting end, the receiver must also have the ability to decode the space-time code, and at the same time need to perform interference cancellation and signal detection. An optimal decoding method commonly used by receivers adopts a joint maximum likelihood (ML) detection method, which decodes received signals in a probabilistic and statistical manner. However, although the joint maximum likelihood estimation method has better performance, the required computational complexity is indeed higher. Another decoding method uses ordered successive interference cancellation (OSIC) detection, which uses the sorting method and the results of the previous iterative operation to cancel the interference and signal to the received signal one by one. detection. For example, assuming that the receiver receives signals from mobile user 1 and mobile user 2, the OSIC detection method will first perform signal detection on mobile user 1, and then deduct (eliminate) the interference of mobile user 1 to obtain mobile User 2's signal. The OSIC detection method is a less computationally intensive but comparable performance technique than the joint ML method. However, it does not further simplify the signal detector by utilizing the orthogonality property of the space-time code.

In addition, the wireless communication environment is a time-varying response, and the transmitting and receiving ends need appropriate adaptive transmission mechanisms to deal with signal distortion and achieve the best service quality. Therefore, a good adaptive transmission mechanism adjustment scheme is also required for the MIMO system.

Contents of the invention

The present invention provides a MIMO communication system and a code selection method thereof, which can utilize the algebraic characteristics of an orthogonal space-time block code (orthogonal STBC, hereinafter referred to as O-STBC) to carry out G-STBC code design, and in a limited loop Under the transmission of information, based on the minimum bit error rate (bit error rate, hereinafter referred to as BER) condition, select an optimal word code structure for transmission.

The invention provides a codeword selection method. The group code selection method is suitable for a communication system with multiple transmitting antennas and multiple receiving antennas. This method includes the following steps. First, the transmitter provides the complex digital form. Next, the receiver receives the word code form, and according to a decoding method, calculates or looks up a table to obtain a corresponding bit error rate (BER) of each of the word codes. Next, the receiver selects a word form with the lowest bit error rate and sends it back to the transmitter. Finally, the transmitter determines the space-time word for data transmission based on the word form with the lowest bit error rate.

The invention also provides a MIMO communication system. The transmitter first provides the complex digital form. The receiver receives the code words, and according to a decoding method, calculates or looks up a table to obtain a corresponding bit error rate of each code word. Among them, the receiver selects a word code form with the minimum bit error rate, and sends it back to the transmitter, and the transmitter determines the space-time word code for data transmission according to the word code form with the minimum bit error rate .

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, preferred embodiments are enumerated below, which are described in detail with reference to the accompanying drawings.

Description of drawings

FIG. 1 shows a schematic diagram of an existing space-time block coding system.

Fig. 2 shows a schematic diagram of another existing space-time block coding system.

FIG. 3 shows a schematic diagram of a communication system according to an embodiment of the present invention.

Fig. 4 shows a flow chart of character code selection according to an embodiment of the present invention.

FIG. 5 and FIG. 6 respectively show the flowcharts of the code selection method in FIG. 4 at the transmitting end and the receiving end.

FIG. 7 shows a schematic diagram of a matched filter channel matrix (MFCM) according to an embodiment of the present invention.

8a-8e respectively show schematic diagrams of five possible group space-time codes when the total number of transmitting antennas is 10 according to the embodiment of the present invention.

Description of reference symbols

300～communication system;

310～transmitter;

312～solve the multitasking module;

314～modulation module;

316～G-STBC encoder;

318～controller;

320～receiver;

322～space-time code matched filter;

324～group type OSIC detector;

326～Multi-tasker;

328～select signal;

T1-TN～transmitting antenna;

R1-RM～receiving antenna;

S410-S460～steps;

S510-S550～steps;

S610-S650～steps;

(K)～orthogonal matrix;

N～total number of transmit antennas;

K ~ symbol time.

Detailed ways

FIG. 3 shows a schematic diagram of a communication system according to an embodiment of the present invention. The communication system 300 includes at least one transmitter 310 and one receiver 320 . Please note that the communication system of the present invention is a transceiver architecture including a receiver and a transmitter design, which can be used in a MIMO system. The transmitter 310 includes a demultiplexing module 312, a modulation module 314, a group-wise space-time block code (group-wise STBC, G-STBC) encoder 316, a controller 318 and N transmission antennas T1～TN. Wherein, the N transmitting antennas T1-TN are divided into Q antenna groups, and each antenna group is composed of 2-4 antennas. The receiver 320 includes a space-time code channel matched filter (matched filter, MF) 322, a group type OSIC detector 324, a multiplexer 326 and M receiving antennas R1～RN, and M≥ Q.

First, at the transmitting end, the input data string is generated by the demultiplexing module 312 into several sub-data strings, modulated into data symbols by the modulator 314, and then passed through the group space-time block code encoder 316 according to the selected The character code structure is space-time coded, and finally transmitted to the receiver 328 by the antennas T1-TN. Wherein, in this embodiment, the code word structure includes the number of antennas used and the required transmission symbol time.

Therefore, at the receiving end, the receiver 320 receives the transmitted signal, and performs signal demodulation through the space-time channel matched filter 322 . Wherein, the space-time channel matched filter 322 is a matched filter channel matrix MFCM, and the space-time code channel matched filter 322 can reduce the spatial dimension of the received signal according to the MFCM for subsequent group OSIC detector 324 to perform further decoding. The decoding principle and form of the matched filter channel matrix MFCM will be described in detail as follows. Next, the group OSIC detector 324 receives the signal after the space-time code channel matched filter 322, and performs interference elimination and signal detection on it according to the OSIC detection rule. The above detection method corresponds to the modulation method used by the transmitting end. For example, when the transmitting end uses BPSK modulation, the detection method of the receiving end is for BPSK detection; when the transmitting end uses QPSK modulation, the detection method for the receiving end is for QPSK detection. In other words, different modulation modes will correspond to different detection methods. Since the decoding of BPSK and QPSK belongs to the detection of real numbers and complex symbols respectively, the following will also discuss the detection methods of real numbers and complex symbols respectively. For example, for the detection of real code elements, the antenna group type OSIC detection method can be directly used for detection, that is, all the symbol data of a certain antenna group can be detected simultaneously in each iterative operation. For the detection of complex code elements, it must cooperate with the antenna group detection method, the two-stage detection method and the recursive method for detection. This is because for the detection of complex code elements, only half of the code elements (ie, L _q pieces) of 2L _q real code elements as the unit block can be detected simultaneously in a certain iterative process of OSIC, If these symbols are not the real part (Re) of the complex symbols belonging to a certain antenna group, they are also the imaginary part (Im). The antenna group detection method for complex code elements refers to averaging the results of the real part (Re) and imaginary part (Im) of the same antenna group to generate a matrix structure similar to real code elements, and the above-mentioned antenna can be used Group OSIC detection method for detection. The method of the two-stage detection rule is to first detect the antenna group with higher link capability (N _q =4 or N _q =3), and then detect the antenna group with lower link capability (N _q =2) to reduce its operational complexity. The recursive method combines the two-stage detection rule, and uses the previous operation result to obtain the next-stage detection symbol, which can effectively reduce its operation complexity. Combining with the above-mentioned decoding method, the computational complexity of the receiver will be reduced, and the design complexity of the receiver will also be simplified.

In addition, in this embodiment, the group OSIC detector 324 calculates or looks up a table one by one according to given environmental parameters to obtain the bit error rate (BER) corresponding to each antenna group. The group OSIC detector 324 finds the antenna group with the smallest BER among all the BERs after calculation, and sends this information back to the transmitter 310 using the selection signal 328 .

Based on the above-mentioned low-complexity group-based OSIC detection framework, the present invention will develop a set of group-based space-time coding without limitation of the total number of transmitting antennas. Under the limitation of the required transmission power and data transmission rate, according to the judging condition of the minimum BER, a space-time code word selection criterion is provided to properly select the best code word.

It should be noted that the optimal space-time code structure for transmission in the present invention depends on the feedback information from the receiver. Therefore, at the beginning, the transmitter can first send a training symbol (training symbol) in the form of a code to the receiver. After the receiver calculates the code with the minimum BER, the transmitter and the receiver then correspond to the minimum BER. The word code structure for actual data transmission. In addition, since the transmitter has different word structures for transmission selection, the design can also be designed so that when the transmission performance is low or the environment changes, the transmitter sends a reselection signal to request the receiver to select Another group of word structures with smaller BER values is used for transmission. Therefore, the present invention can provide an adaptive transmission adjustment mechanism.

Fig. 4 shows a flow chart of character code selection according to an embodiment of the present invention. First, the transmitter 310 is divided into Q antenna groups according to the number N of transmitting antennas to provide possible space-time code forms (step S410). Wherein, since the signal in the present invention is coded by O-STBC, the number of antennas in each antenna group can only be 2, 3 or 4 in order to conform to the characteristics of orthogonality. The selection of this code form includes different antenna configuration methods. For example, assuming that the total number of transmitting antennas N is 10, the antenna configuration specified by one of the code forms may be 2 antennas as a group. Therefore, a total of 5 antenna groups can be divided into ∑ ₁ = (2, 2, 2, 2, 2) means. Similarly, assuming that another codeword form uses 3 antennas and 4 antennas as a group, it can be represented by Σ ₂ =(3, 3, 4). Assuming that there are T1~T10 antennas in total, according to the code format of ∑ ₁ , T1 and T2 will be used as a group to transmit data at the same time, and T3 and T4 will be used as a group to transmit data at the same time; if according to the code format of ∑ ₂ , then T1, T2 and T3 will be a group used to transmit data at the same time. Then, the Q antenna group form is transmitted to the receiver 320 . The receiver 320 receives the code (in the form of an antenna group) (step S420), and calculates or looks up a table to obtain the BER value corresponding to each space-time code (step S430). The above calculation or table look-up method will be described in detail as follows. Next, the receiver 320 finds the word code with the smallest BER, and returns a selection signal including this information to the transmitter 310 (step S440). Then, the transmitter 310 determines the word structure for transmission according to the word structure specified in the selection signal (step S450). Finally, the transmitter and receiver use the word structure to transmit data (step S460).

Please refer to FIG. 5 and FIG. 6 , which respectively show the flowcharts of the character selection method in FIG. 4 at the transmitting end and the receiving end. As shown in FIG. 5 , the transmitter 310 is divided into Q antenna groups according to the total number of transmitting antennas N to generate possible candidate codes (step S510 ). The properties of the space-time code, including coding rate, diversity gain, and receiver computational complexity, will be affected by the structure of the antenna group (ie, the code structure). For the total number of N transmit antennas, even with the same number of antenna groups, different antenna group structures can provide different coding rates. Furthermore, different antenna group structures can provide different diverse gains, resulting in different communication link performances. In addition, based on the group-type OSIC detection rule, different antenna group structures will also lead to different operational complexity of the receiver. Therefore, the selection of the best space-time code should consider the above three characteristics at the same time. Table 3 lists all possible space-time code selection L ^N from the total number of antennas N=2 to N=16 and the corresponding coding rate R ^N . In Table 3, J ^N represents the number of possible code words when the total number of antennas is N, S ^N represents the antenna configuration mode of each code word, and L ^N represents the number of iterative operations required for OSIC detection. Therefore, different total transmit antenna numbers N will have different possible word structures.

N J ^N Possible antenna group combinations, S ^N code rate Maximum number of iterations 2 1 (2) 1 1 3 1 (3) 0.5 1 4 2 (4), (2, 2) 0.5, 2 1, 2 5 1 (2,3) 1.5 4 6 3 (3,3), (2,4), (2,2,2) 1, 1.5, 3 2, 4, 3 7 2 (3,4), (2,2,3) 1, 2.5 2,6 8 4 (4, 4), (2, 3, 3), (2, 2, 4), (2, 2, 2, 2) 1, 2, 2.5, 4 2, 6, 6, 4 9 3 (3,3,3), (2,3,4), (2,2,2,3) 1.5, 2, 3.5 6, 3, 8 10 5 (3, 3, 4), (2, 4, 4), (2, 2, 3, 3), (2, 2, 2, 4), (2, 2, 2, 2, 2) 1.5, 2, 3, 3.5, 5 3, 6, 8, 8.5 11 4 (3, 4, 4), (2, 3, 3, 3), (2, 2, 3, 4), (2, 2, 2, 2, 4) 1.5, 2.5, 3, 4.5 3, 8, 8, 10 12 7 (4, 4, 4), (3, 3, 3), (2, 3, 3, 4), (2, 2, 4, 4), (2, 2, 2, 3, 3), (2 , 2, 2, 2, 4), (2, 2, 2, 2, 2, 2) 1.5, 2, 2.5, 3, 4, 4.5, 6 3, 4, 8, 8, 1010, 6 13 5 (3, 3, 3, 4), (2, 3, 4, 4), (2, 2, 3, 3, 3), (2, 2, 2, 3, 4), (2, 2, 2 , 2, 2, 3) 2, 2.5, 3.5, 4, 5.5 4, 8, 10, 10, 12 14 8 (3, 3, 3, 4), (2, 4, 4, 4), (2, 3, 3, 3, 3), (2, 2, 3, 3, 4), (2, 2, 2 , 4, 4), (2, 2, 2, 2, 3, 3), (2, 2, 2, 2, 2, 4), (2, 2, 2, 2, 2, 2, 2) 2, 2.5, 3, 3.5, 4, 5, 5.5, 7 4, 8, 10, 10, 1012, 12, 7 15 7 (3, 4, 4, 4), (3, 3, 3, 3, 3), (2, 3, 3, 3, 4), (2, 2, 3, 4, 4), (2, 2 , 2, 3, 3, 3), (2, 2, 2, 2, 3, 4), (2, 2, 2, 2, 2, 2, 3) 2, 2.5, 3, 3.5, 4.5, 5, 6.5 4, 5, 10, 10, 1212, 14

16 10 (4, 4, 4, 4), (3, 3, 3, 3, 4), (2, 3, 3, 4, 4), (2, 2, 4, 4, 4), (2, 2 , 3, 3, 3, 3), (2, 2, 2, 3, 3, 4), (2, 2, 2, 2, 4, 4), (2, 2, 2, 2, 2, 3 , 3), (2, 2, 2, 2, 2, 2, 4) (2, 2, 2, 2, 2, 2, 2, 2) 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 6.5, 8 4, 5, 10, 10, 1212, 12, 14, 14, 8

Table three

Figures 8a-8e are 5 possible character codes (3, 3, 4), (2, 4, 4), (2, 2, 3, 3) when the total number of transmitting antennas is 10 according to the embodiment of the present invention respectively. ), (2,2,2,4) and (2,2,2,2,2). For example, taking Figure 8c as an example, it shows that the total number of transmitting antennas N=10, divided into Q=4 antenna groups, and the code (antenna group structure) structure is (2, 2, 3, 3) Schematic diagram of the G-STBC character code structure, in which, the part with 2 antennas uses 2×2 STBC, the part with 3 antennas uses 3×8 STBC, and the STBC used in each group is positive Interleaved STBC (O-STBC), the code word structure takes the symbol time length N=8 as the unit. It can be seen from Figures 8a-8e that, under the condition that the space-time codes in each group must be orthogonal, the antenna group structure will also determine the code word structure.

Next, transmit these possible space-time code forms to the receiver 320 (step S520). Next, wait for the receiver 320 to return a message. Then, it is determined whether the receiver 320 has returned information (step S530). If the receiver 320 has not returned any information (No in step S530), return to step S530 and continue to judge. If the receiver 320 has sent back the information (Yes in step S530), the transmitter 310 determines the best word as the space-time word for transmission according to the best word in the returned information ( Step S540). Finally, the best space-time word code is used to encode the data and transmit it to the receiving end for data transmission (step S550).

At the receiving end, as shown in FIG. 6 , the receiver 320 receives the space-time code form sent by the transmitter 310 (step S610 ). This code format contains different antenna configuration methods. For example, assuming that the total number of transmitting antennas N is 10, it can be known from Table 3 that it includes 5 possible word structures. Next, according to the decoding method, calculate (look up a table) to obtain a BER value corresponding to each space-time code (step S620). With reference to Table 3, it can be seen that when the total number of transmitting antennas N is 10, five BER values BER1- _BER5 will be obtained after step S620 is executed. There is a corresponding BER value BER1, the character code Σ ₂ (3, 3, 4) has a corresponding BER value BER2, and so on. Next, find the word format with the minimum BER value (step S630). For the spectrum efficiency h(M _j ^N ) required by a system, if the bit transmission rate R _b (ie modulation form) is given, then the corresponding space-time code will be defined. Therefore, under the constraints of the given total transmission power _PT and the required data transmission rate R _b , if the jth word code is selected, it needs to satisfy

$\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arg</span>}\underset{<span\; class="notranslate">\; \&ForAll;</span>\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; min</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; .</span>$

Among them, P _e represents the overall BER value of the jth character code, which can be calculated as follows:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&eta;</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; Q</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}^{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}^{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>$

In the above formula, P _{e, q} (j) is the BER of the qth antenna group under the jth mode (mode), and the mode is defined as a combination of a specific space-time code and its modulation form . Assuming that the error propagation effect (error propagation effect) is ignored during the iterative operation of OSIC, P _{e, q} (j) can be approximated as the signal-to-interference-plus-noise ratio (signal-to-interference-plus-noise ratio, SINR)γ _q and transmission data rate R _{b, function of q}

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; \&ap;</span>{\mathrm{<span\; class="notranslate">\; g</span>}}_{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

in

and

${\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; q</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="v"\; filenames="H061D1798920061020E000072.png,H061D1798920061020E000091.png"\; state="\{\{state\}\}">v</figure-callout></span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}_{{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}_{{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}$

${\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; e</span>}}_{{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; v</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; I</span>}<span\; class="notranslate">\; ]</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; e</span>}}_{{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}$

定义如H_c，i(H_c，i将于后面介绍)，e_l则是在

中第l个单位标准向量(unit standardvector)。本发明假设使用M-ary QAM调制，则第q个天线群组的BER可近似如下Each is the detected noise power and symbol mean square error of the qth antenna group. in

Defined as H _{c, i} (H _{c, i} will be introduced later), e _l is in

The lth unit standard vector in (unit standardvector). The present invention assumes the use of M-ary QAM modulation, then the BER of the qth antenna group can be approximated as follows

${\mathrm{<span\; class="notranslate">\; g</span>}}_{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&ap;</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; q</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\sqrt{{\mathrm{<span\; class="notranslate">\; 2</span>}}^{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; q</span>}}}}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; erfc</span>}<span\; class="notranslate">\; (</span>\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 1.5</span>}{\mathrm{<span\; class="notranslate">\; \&gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}{{\mathrm{<span\; class="notranslate">\; 2</span>}}^{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; q</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; )</span>$

in, $2^{R_{b,q}}=\stackrel{\&OverBar;}{m},$ erfc() is a complementary error function.

It can be known from the above formula that, under the limitation of the required transmission power _PT and data transmission rate R _b , according to the BER performance, the word code corresponding to the minimum BER performance can be selected. Assume that BER2 is the minimum BER value among all calculated BER values. This code format corresponding to the minimum BER value will be regarded as the best space-time code format, so the best code format is its corresponding code format ∑ ₂ , that is, (3, 3, 4) will be the best character code format. Therefore, the receiver 320 generates a selection signal, which includes the information of the optimal code format of _Σ2 , and sends the selection signal back to the transmitter 310 (step S640). Finally, the transmitter 310 performs encoding according to the optimal code format (∑ ₂ ), and then transmits data with the receiver (step S650).

In summary, the transmission system and transmission method according to the present invention can improve the link quality and increase the data rate, and can also achieve a better balance between the two. In addition, since the transmitting end uses the O-STBC encoding method, the computational complexity of the receiver can be effectively reduced.

In order to illustrate the determination method of the above-mentioned antenna group and the relationship and influence among various correlation operations, mathematical formulas will be used for description below. Please note that the following quotes part of the results of the doctoral thesis "Space-time signal processing for MIMO wireless communications: Space-time signaling and interference suppression" (hereinafter referred to as document 1) of the same inventor of the present invention. For the detailed derivation process, please refer to the inventor's Paper, the following is only an excerpt of some of its results, and it has been improved to assist in the explanation.

First define the format of the data, consider the G-STBC system in the Rayleigh flat-fading environment, as shown in Figure 3, where N antennas are placed at the transmitting end, and M antennas are placed at the receiving end. N transmit antennas are divided into Q antenna groups (N ₁ , . . . , N _Q ), and each antenna group uses 2-4 antennas, so that N ₁ + . . . +N _Q =N. For the qth group, the continuous B _q data symbols are coded by O-STBC code, and transmitted by N _q antennas within K _q symbol time.

If K=max{K ₁ , . . . , K _Q } is defined, then K=k _q K _q , where k _q =K/K _q . Each antenna group will be able to transmit L _q = k _q B _q independent symbols in K symbol time, therefore, Q antenna groups transmit a total of

${\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; :</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; K</span>}\underset{\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\frac{{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}{{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}$

data symbols. The codeword of each antenna group, called the group code, can be completely described by the space-time codeword matrix X _q of N _q ×K. Divide the qth group data symbol s _q (k) into data string blocks such as

${\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; l</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; l</span>}}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}$

Then the space-time character code of the qth group can be written as

${\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; :</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; l</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; l</span>}}{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}_{\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; l</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Wherein A _{q, l} is a space-time modulation matrix (modulation matrix). For the convenience of subsequent analysis, the following definition ${\widetilde{\mathrm{the\; s}}}_{q,l}\left(k\right)=\mathrm{Re}\left\{{\mathrm{the\; s}}_{q,l}\left(k\right)\right\},l=1,...,L_q,$ and ${\widetilde{\mathrm{the\; s}}}_{q,l}\left(k\right)=\mathrm{Im}\left\{{\mathrm{the\; s}}_{q,l-L_q}\left(k\right)\right\},1=L_q+1,...,2L_q.$

Assuming that M(≥Q) antennas are used at the receiving end, the signals received on M antennas within K symbol time are

$\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; :</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\sqrt{\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}{\mathrm{<span\; class="notranslate">\; N</span>}}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</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>$

in $h_q=\sqrt{P_q}{C}_q,$ P _q is the transmission power of the qth group, and it satisfies P ₁ +...+P _Q = _PT , and P _T is the total transmission power; in addition, C _q is the MIMO from the qth group to the receiver Channel matrix, and finally V(k)∈C ^M×K is the noise matrix. The following assumptions will be used in the discussion that follows:

(a1) data symbol s _q (k), q=1, ..., Q, is iid, its average value is 0 (zero-mean), and the variation number is 1 (unit-variance), and adopts the same modulation technique.

(a2) Each antenna group transmits the same power, that is, P ₁ =...=P _Q =P _T /Q.

(a3) C _q , q=1,..., Q, each element in the matrix is an iid complex Gaussian random variable with an average value of 0 and a variation of 1, and it is assumed that the constant.

(a4) V(k) is space-time white noise with an average value of 0 and a variance of s _v ² .

(a5) According to O-STBC, when using real code elements and 2≤N _q ≤4, or using complex code elements and N _q =2, use an orthogonal space-time zone with a coding rate of 1 (unit-rate) block code; and when complex symbols are used and 3≤N _q ≤4, an orthogonal space-time block code with a coding rate of 1/2 (half-rate) is used.

Real Vector Model

For the convenience of analysis, (2) is rewritten as the following 2KM×1 linear vector model

${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; :</span><span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>$

(3)

in

$\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; :</span><span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span>\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; m</span>}}$

${\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; :</span><span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span>\mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span><span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}$

${\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; :</span><span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; T</span>}}$

H _c ∈ R ^2KM×2LT

is the equivalent channel matrix, and

${\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; :</span><span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; [</span>{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>{\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}_{\mathrm{<span\; class="notranslate">\; Q</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; ,</span>$

v _c (k) ∈ ^R2KM is a noise vector. Multiplying the left and right sides of the y _c (k) equation by H _c will generate a matched-filtered (MF) data vector

$\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; :</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; f</span>}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

in $f:=h_c^T{h}_c\&Element;R^{2L_T\&times;{2L}_T}$ For the matched filter channel matrix (matched-filtered channelmatrix, MFCM), $v\left(k\right):=h_c^T{v}_c\left(k\right).$ The signal will be detected based on model (4) below.

OSIC detection using real code elements

In the following, the algorithm proposed in Document 1 is used to detect the transmitted signal. By using the special structure of the matched filter channel matrix F, the OSIC detector can simultaneously detect all L _q =K symbol data of a certain antenna group in each iteration operation, which is called "antenna group OSIC detection method.

A. Matched filter channel matrix

In order to make the OSIC law detect the transmission signal effectively, the structure of F must be analyzed. Since the detection rule has been proposed and analyzed completely in Document 1, it can be applied to the case of real code elements, so only the results are presented here.

Define O(K) as a set of all K×K real orthogonal matrices with K independent variables; (K, L) is a set of all K×K real orthogonal matrices with L independent variables gather.

Result II.1: Consider real code elements, and 2≤N _p , N _q ≤4. According to O-STBC, it can be known that K∈{2, 4}. Define F _{p, q} as the (p, q)th K×K block matrix of F, where F is defined in (4). Then it can be known that F _q,q =α _q I _K and F _p,q ∈(K), if p≠q. ,

The results of Result II.1 are summarized in Table 1, where F _p,q ^(s,t) is the (s,t)th block matrix of F _q,q . The structure diagram of F is shown in Fig. 7 .

Table I

B. Group OSIC detection algorithm

Next it will be found that F ^-1 will, roughly speaking, have the same structure as F. Firstly, Φ _KL (L) is defined as a set of all invertible KL×KL real symmetric matrices, so that for X∈Φ _KL (L), where X _{k, l} is the For the (k, l)th K×K sub-matrix, X _{l, l} = β _q I _K and X _{k, l} ∈ O(K) when k≠l.

Fact II.1: If F ∈ Φ _KL (L), then F ^-1 also has the same result (see Document 1). ,

From fact II.1, the following result II.2 can be obtained:

Result II.2: Considering real code elements, and 2≤N _p , N _q ≤4, we know that K∈{2, 4}. F ∈ R ^{LT × LT} is defined in (4). Then each F ^- 1 K×K block diagonal (diagonal) sub-matrix is a constant identity matrix; each F ^-1 off-diagonal (off-diagonal) K×K block sub-matrix belongs to O( K). It can be seen that all KL diagonal elements of F ^-1 have L=Q different levels (level) β _l , l=1,...,L, that is

diag(F ^-1 )={β ₁ ,...,β ₁ ,β ₂ ,...,β ₂ ,...,β _L ,...,β _L }(5),

Among them, there are K number of each level β _l in (5). It can be seen from (5) that based on the zero-forcing (ZF) criterion (or the minimum mean square error (MMSE) criterion), the OSIC detector can simultaneously detect K symbols in the initial iterative operation .

Based on the detection-subtraction program of OSIC, it can be known that in the i-th iterative operation of OSIC, i=1,...,L-1, the noise covariance (covariance) matrix is F _i ^-1 , where

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

is the matched filter channel matrix in the iterative operation of OSIC, which can be deleted by deleting i blocks (that is, H _{c, i} ) with units of K rows (columns) from H _c (corresponding to the previous iteration signal detected during operation). It can be known that F _i ∈ F(Li).

且Result II.3: From Fact II.1, it follows that

and

$\mathrm{<span\; class="notranslate">\; diag</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

Among them, β _{i, l} are the first different levels distributed on the F _i ^-1 diagonal line, and each β _l has K pieces. ,

It can be seen from the above analysis that the above algorithm can perform antenna group OSIC detection.

OSIC detection using complex symbols

Although the antenna group type OSIC detection can be performed under the use of real code elements. However, under the use of complex symbols, the antenna group OSIC detection will not be possible. Only half of the code elements (ie, L _q ) of the unit block consisting of 2L _q real code elements can be detected simultaneously in a certain iterative process of OSIC, and if these symbols do not belong to a certain antenna group The real part of the complex code element in is its imaginary part.

A. Matched filter channel matrix

Under complex symbols, there are the following results that differ from Result II.1.

Result III.1: Consider complex symbols, and 2≤N _p , N _q ≤4. According to O-STBC, it can be known that K∈{2, 8}. Define F _p,q as the (p,q)th 2L _q ×2L _q block matrix of F, where F is defined in (4). Then the results shown in Table 2 can be obtained.

Table II

B. Group OSIC detection algorithm

From result III.1, it can be speculated that F _i ^-1 will no longer have a structure similar to F _i . Before analyzing the structure of F _i ^-1 , the following parameters need to be defined. Firstly, it is defined that in the iterative operation of OSIC, half of the real code elements for a certain antenna group are a decision group (decision group) Γ _{i, g} , g=1,..., G _i , where , G _i is the total number of decision-making groups in the iterative operation. Therefore, each antenna group will have two decision groups, and each decision group has _Lq real symbols. Further define I _{i, 1} and I _{i, 1/2} to be the set of decision group labels (index) of space-time codes with coding rate 1 and coding rate 1/2 in iterative operation respectively, so G _i,1 =|I _i,1 | and G _i,2 =|I _i,2 | are the number of parameters included in each set. Finally, I _i is defined: =I _{i, 1∪I i, 1/2} is the set of the total decision group labels in the iterative operation, so G _i =|I _i |. According to the above definition, it can be seen that

(8)

In addition, if the elements on the diagonal of F _i are divided into G _i decision groups, and each decision group has the same non-zero value, that is

Suppose {a _{i, g} } _g=1 ^Gi has D _i (G _i ) different levels, then we can know

为一组所有可反逆的J×J的实数对称矩阵的集合，使得对于

而言，可得：(1)X的每一个区块对角子矩阵为一个常数单位矩阵

，g＝1，...，G，其中M_g ∈{2，4，8}。(2){a_g}_g＝1 ^G具有D个不同的层级，其中

(3)对于i，j＝1，...，G，i≠j，X的M_i×M_j区块非对角子矩阵中的每一个4×4区块子矩阵属于(4)或是零矩阵。其中，当D＝G，则

将改写为

Next define

is a set of all reversible J×J real symmetric matrices, such that for

In terms of, it can be obtained: (1) Each block diagonal sub-matrix of X is a constant identity matrix

, g=1, . . . , G, where M _g ∈ {2, 4, 8}. (2){a _g } _g=1 ^G has D different levels, where

(3) For i, j=1,..., G, i≠j, each 4×4 block sub-matrix in the M _i ×M _j block off-diagonal sub-matrix of X belongs to (4) or zero matrix. Among them, when D=G, then

will be rewritten as

定义i(g)，g＝1，...，G_i，为i中第g的元素，而F_i∈R^Ji×Ji为OSIC第i次迭代运算中的匹配滤波通道矩阵，其中Result III.2: Consider complex code elements. Assume that space-time codes with a coding rate of 1 and a coding rate of 1/2 exist in the iterative operation of OSIC at the same time, that is and

Define i(g), g=1,..., G _i is the gth element in i, and F _i ∈ R ^Ji×Ji is the matched filter channel matrix in the iterative operation of OSIC, where

And L _g ∈ {2, 4, 8}. ,

Therefore, if but From the result III.2, we know that F _i ^-1 has G _i (≥D _i ) different levels {β _{i, g} } _g=1 ^Gi (wherein F _i only has D _i different levels), that is

It can be seen from (11) that only half of the code elements (ie, L _q ) of the block with 2L _q real code elements as the unit can be detected simultaneously in a certain iterative process of OSIC, and if these code elements do not belong to The real part of the complex code element in a certain antenna group is its imaginary part. Therefore, such a detection feature will cause a computational burden. In order to solve the above-mentioned problems, some techniques for reducing the computational complexity will be developed later.

Implementation Issues of Group-based OSIC Detection Techniques Using Complex Code Elements

Here, some implementation issues of group-based OSIC detection will be discussed, including antenna group-based detection algorithm, two-stage detection algorithm and recursive implementation. Since the implementation of the group OSIC detection using real code elements can be accomplished by the method proposed in Document 1, the following only discusses how to implement the group OSIC detection technology using complex code elements.

A. Antenna group detection method

个元素将具有二个不同的层级

及

。为实现天线群组式检测，一种最简单的方法即是直接搜寻F_i ^-1对角在线决策群组的标号，检查其哪一个标号所对应的层级最小。此一方法虽简单但性能也较差。因此，将对应于某一天线群组的二层级及

进行平均As stated in Result III.2, a group of antennas distributed on the F _i ^-1 diagonal line share

elements will have two different levels

and

. In order to realize antenna group detection, one of the simplest methods is to directly search for labels of the F _i ^-1 diagonal online decision group, and check which label corresponds to the smallest level. Although this method is simple, its performance is also poor. Therefore, the second level corresponding to a certain antenna group and

average

${\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}_{{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 12</span>}<span\; class="notranslate">\; )</span>$

个元素改写为and the diagonal of F _i ^-1x on the total line

elements rewritten as

According to β _{i, 1 ,} β _{i, 2} , . This method of searching for labels is not optimal, so its performance will be degraded, but computer simulations show that the degraded performance is not serious.

B. Two-stage detection method

Theoretically, antenna groups with higher diversity gain (that is, with more antenna numbers or lower coding rates) are more robust against channel fading and have better performance. In view of this, the present invention proposes a two-stage detection rule. The method is to first detect the antenna group with a lower coding rate (N _q =4 or N _q =3) and then detect the antenna group with a higher coding rate (N _q =2), so as to reduce its computational complexity. Likewise, this method of searching for labels is not optimal, so there is some degradation in performance, but computer simulations show that the performance degradation is not severe.

C. Recursive Form Implementation

In order to further reduce the amount of computation in the receiver, a group-type OSIC detector is implemented using a recursive rule similar to that proposed in Document 1. However, the method proposed in Document 1 cannot be directly and completely applied to this invention, and some modifications are required before it can be used.

中能够形成正交矩阵的最小维度为4×4，其中，为F_i ^-1的第(p，q)个子矩阵。因为此一基于递归法则的实现，一次只能处理一个区块正交矩阵，因此当F_i的维度很大时，直接对其群组式OSIC检测器以递归方式实现将需要较多的递归次数，造成较大的计算量。但幸运地，若结合二阶段式检测法则，将可辅助降低其运算量。假设在F_i ^-1对角在线属于某一天线群组的元素具有二个不同的层级。若F_i为第i个迭代运算中的匹配滤波通道矩阵。则F_i1 ^-可分割如下From the result III.2, we can see that in

The minimum dimension that can form an orthogonal matrix in is 4×4, where, is the (p, q)th sub-matrix of F _i ^-1 . Because this implementation based on the recursive rule can only process one block-orthogonal matrix at a time, when the dimension of F _i is large, it will require more recursive times to directly implement the group OSIC detector in a recursive manner , resulting in a large amount of computation. But fortunately, if it is combined with the two-stage detection algorithm, it will help to reduce its calculation load. It is assumed that the elements belonging to a certain antenna group on the F _i ^-1 diagonal line have two different levels. If F _i is the matched filter channel matrix in the iterative operation. Then F _i1 ^- can be divisible as follows

(13)

in $B_{i-1}\&Element;R^{2(L_T-{\mathrm{\&Sigma;}}_{j=1}^{i-1}{L}_{q_j})\&times;{2L}_{q_{i-1}},}$ ${\mathrm{D.}}_{i-1}=d_{i-1}{I}_{2L_{q_{i-1}}},$ And d _i-1 is a constant. Further, if suppose $2(L_T-{\mathrm{\&Sigma;}}_{j=1}^{i-1}{L}_{q_j})\&times;2(L_T-{\mathrm{\&Sigma;}}_{j=1}^{i-1}{L}_{q_j})$ Dimension F _i-1 is the principle submatrix of F _i-1 ^-1 , and $f_0^{-1}=f^{-1}.$ From (13) and using the inversion lemma for block matrix, F _i-1 can be expressed as follows

${\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; )</span>}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 14</span>}<span\; class="notranslate">\; )</span>$

It can be known from (14)

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 15</span>}<span\; class="notranslate">\; )</span>$

Using matrix inversion lemma, and derivation can be obtained

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 16</span>}<span\; class="notranslate">\; )</span>$

in, ${\mathrm{E.}}_{i-1}:={\stackrel{\&OverBar;}{f}}_{i-1}{B}_{i-1}$ and

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; f</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; B</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{{\mathrm{<span\; class="notranslate">\; L</span>}}_{{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}}& {\mathrm{<span\; class="notranslate">\; 0</span>}}_{{\mathrm{<span\; class="notranslate">\; L</span>}}_{{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}}\\ {\mathrm{<span\; class="notranslate">\; 0</span>}}_{{\mathrm{<span\; class="notranslate">\; L</span>}}_{{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}}& {\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="c"\; filenames="H061D1798920061020E000072.png,H061D1798920061020E000091.png"\; state="\{\{state\}\}">c</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}_{{\mathrm{<span\; class="notranslate">\; L</span>}}_{{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}}\end{array}\right]$

in, $c_{j,i-1},j=\mathrm{1,2},$ is a constant.

Using the information of F _i-1 and F _i-1 ^-1 , the above derivation provides a simple recursive formula to calculate F _i ^-1 without any direct inverse matrix operation, thus effectively reducing its operation the complexity.

The above description provides several different embodiments or embodiments applying different features of the invention. The specific devices and methods in the examples are used to help explain the main spirit and purpose of the present invention, but of course the present invention is not limited thereto.

Therefore, although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art can make some changes and modifications without departing from the spirit and scope of the present invention. The protection scope of the invention shall be determined by the claims of the present invention.

Claims (20)

1. A character code selection method is applicable to a multi-input multi-output communication system, the communication system has multiple transmitting antennas and multiple receiving antennas, the method comprising: a transmitter providing complex digital form; A receiver receives the codeword form, and according to a decoding method, calculates or looks up a table to obtain a corresponding bit error rate of each said codeword form; the receiver selects a word form with the lowest bit error rate and sends it back to the transmitter; and The transmitter determines the word code for data transmission according to the word code form with the minimum bit error rate, Wherein each of said word codes adopts orthogonal space-time code encoding, and the decoding method is a sorting progressive interference cancellation detection method, and wherein under complex symbols, the receiver also adopts a matched filter The different levels of the elements belonging to an antenna group on the diagonal of the inverse matrix of the channel matrix are averaged for the sorted progressive interference cancellation detection. 2. The word code selection method as claimed in claim 1, wherein the transmitter performs the following steps: generating the codeword form according to the number of the transmitting antennas; receives the one-word form of the receiver; and According to the received character code form, determine the character code for transmission, and use the determined character code for transmission. 3. The word code selection method as claimed in claim 1, wherein the receiver performs the following steps: receiving said codeword form from the transmitter; Calculate the corresponding bit error rate of each said codeword form according to the decoding method; and sending a selection signal to the transmitter for determining the character code for transmission by the transmitter, Wherein the selection signal includes the information of the word code with the minimum bit error rate. 4. The method for character selection as claimed in claim 1, wherein the character selection is a space-time character selection. 5. The code word selection method according to claim 1, wherein each of said code words includes N _q antennas, and N _q is 2, 3 or 4. 6. The code word selection method according to claim 5, wherein the number N _q of antennas in each said code word is different. 7. The code word selection method according to claim 1, wherein the sorting and progressive interference elimination detection method is also combined with a two-stage detection method for detection. 8. The code word selection method as claimed in claim 7, wherein the two-stage detection method comprises first detecting a code word group with 3 or 4 antennas, and then detecting a code word group with 2 antennas. 9. The character code selection method as claimed in claim 8, wherein the two-stage detection method comprises two-stage detection using a recursive detection method. 10. The code word selection method as claimed in claim 1, wherein under the detection of real code elements, the receiver uses the sorting progressive interference cancellation method to perform antenna group detection. 11. A communication system having multiple transmit antennas and multiple receive antennas, comprising at least: a transmitter for providing complex digital form; and A receiver receives the code word form, and calculates or looks up a table to obtain a corresponding bit error rate of each code word form according to a decoding method, Wherein the receiver selects a word code form with the minimum bit error rate, and sends it back to the transmitter, and the transmitter determines the word code for data transmission according to the word code form with the minimum bit error rate, Wherein each of said word codes adopts an orthogonal space-time code encoding, and the decoding method is a sorting progressive interference cancellation detection method and wherein under complex symbols, the receiver also adopts a matched filter channel The different levels of the elements belonging to an antenna group on the diagonal of the inverse matrix of the matrix are averaged for the sorted progressive interference cancellation detection. 12. The communication system as claimed in claim 11, wherein the transmitter further comprises: A multitasking module for generating multiple sub-data strings from the input data; A modulation module, used to modulate the sub-data strings into complex modulation symbols; a group space-time block code encoder, for performing group space-time block coding on the modulated modulation symbols; and A controller is used to provide the word code form, and determine the word code for data transmission according to the word code form with the minimum bit error rate returned by the receiver. 13. The communication system as claimed in claim 12, wherein the receiver further comprises: A space-time code channel matched filter for reducing the spatial dimension of the coded signal transmitted by the transmitter; a detector for detecting the encoded signal; and A multiplexer is used to restore the detected signal to the original data. 14. The communication system as claimed in claim 13, wherein each of the word codes includes N _q antennas, and N _q is 2, 3 or 4. 15. The communication system as claimed in claim 14, wherein the number _{Nq of} antennas in each of said code words is different. 16. The communication system as claimed in claim 11, wherein the sequential and progressive interference cancellation detection method is combined with a two-stage detection method for detection. 17. The communication system as claimed in claim 16, wherein the two-stage detection method comprises first decoding a code group with 3 or 4 antennas, and then decoding a code group with 2 antennas. 18. The communication system as claimed in claim 17, wherein the two-stage detection method comprises a recursive detection method for detection. 19. The communication system as claimed in claim 13, wherein the detector is a detector performing sequential progressive interference cancellation for antenna group detection under the decoding of real symbols. 20. The communication system as claimed in claim 13 , wherein under complex symbols, the detector performs an average of a signal of a real part and an imaginary part of each said code word for antenna grouping type detection detector.

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