CN103414534B - A kind of generalized spatial modulation system receiver detection method in conjunction with threshold judgement - Google Patents

Abstract

The invention discloses a kind of generalized spatial modulation system receiver detection method in conjunction with threshold judgement, by sorting to emitting antenna combination, detection of transmitted signals under emitting antenna combination after adopting balanced detection algorithm to detect sequence, and it is whether reliable in conjunction with threshold judgement detection of transmitted signals, once there be reliable detection of transmitted signals namely to it can be used as final estimation to send signal, only have when all detection of transmitted signals are all unreliable, just can need to travel through all detection of transmitted signals and select optimum conduct to estimate to send signal.The present invention, by threshold judgement, can reduce the possible detection of transmitted signals number of search, thus effectively reduce the detection complexity of receiver, and obtain preferably detection perform when lower complexity.

Description

A Receiver Detection Method for Generalized Space Modulation System Combined with Threshold Judgment

technical field

The invention belongs to the technical field of mobile communication, and more specifically relates to a receiver detection method of a generalized space modulation system combined with threshold judgment.

Background technique

Spatial Modulation (SM) technology divides a fixed number of information bits into two parts, one part is used to select the transmitting antenna, the other part is used to map the constellation symbols, and the mapped constellation symbols are transmitted through the selected transmitting antenna, and the unselected The transmitting antenna is silent. The use of SM technology can avoid the problems of inter-channel interference and transmitting antenna synchronization in MIMO (Multiple-Input Multiple-Output) systems. The Generalized Spatial Modulation (GSM) technology can select multiple transmitting antennas, and transmit different constellation symbols on different transmitting antennas, so as to improve the spectrum utilization of the system. For details, see: J.T.Wang, S.Y.Jia, J. Song, "Generalised spatial modulation system with multiple active transmitant tennas and low complexity detection scheme," IEEE Transactions on Wireless Communications, vol.11, no.4, pp.1605–1615, Apr.2012. The generalized spatial modulation technology extends the spatial modulation technology and increases the number of active transmit antennas per time slot , and transmit different modulation symbols on different transmit antennas, thereby improving the transmission efficiency and spectrum utilization of the system. However, when detecting the MIMO receiver based on generalized spatial modulation technology, it is necessary to detect not only the position of the activated transmitting antenna, but also the modulation symbol carried by each activated transmitting antenna. Therefore, in order to obtain the optimal performance, the It is necessary to perform an ergodic search on all possible transmitted signals, and use methods such as maximum likelihood criterion or maximum a posteriori probability criterion to perform decision detection, so that the complexity of the receiver is very high.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the prior art, provide a generalized spatial modulation system receiver detection method combined with threshold judgment, reduce the number of searches for possible transmitted signals, thereby reducing the detection complexity of the receiver.

In order to realize the above-mentioned object of the invention, the generalized space modulation system receiver detection method of the present invention in conjunction with threshold judgment is characterized in that comprising:

S1: The received signal of the receiver is a column vector y=Hx+n of _NR × 1, where _NR is the number of receiving antennas, H is the channel matrix of the MIMO system, x is the transmitted signal of the transmitter of the generalized spatial modulation system, n is an additive white Gaussian noise with a mean value of 0 and a variance of ^σ2 ; the received signal y is preprocessed to obtain a preliminary equalized signal z of the received signal;

S2: Select the active transmit antenna according to each combination in the preset transmit antenna combination mapping table, and extract the corresponding elements in the preliminary equalized signal z to form a new vector z _k , k=1,2,...,N, where N is the mapping The total number of transmit antenna combinations in the table; obtain the possibility weight w _{k of the corresponding transmit antenna combination according to z k ;}

S3: Sort the transmit antenna combination from large to small according to the possibility weight w _k , and C _n represents the nth transmit antenna combination after sorting;

S4: Use the balanced detection method to detect and obtain the detection signal t _n corresponding to the nth transmitting antenna combination C _n after sorting, demodulate the detection signal t _n to obtain the detected constellation symbol data, and distribute the detected constellation symbol data to the transmitting antenna combination Each antenna in C _n gets the detection transmission signal Judgment detection send signal Whether it is reliable, the decision threshold is V _theshold = N _R σ ² , once Where ||·|| _F means to find the Frobenius norm, then estimate the sent signal Enter step S5, otherwise continue to detect and judge the transmitting antenna combination after the next sorting; if all transmitting antenna combinations cannot use then send a signal from all detections Select the optimal detected transmitted signal as the estimated transmitted signal Go to step S5;

S5: Send a signal based on the estimate The corresponding transmitting antenna combination and the mapping table of the modulation constellation are respectively demapped to restore the original binary bit information sequence.

The receiver detection method of the generalized space modulation system combined with the threshold judgment in the present invention, by sorting the combinations of transmitting antennas, adopting an equalization detection algorithm to detect the detection transmission signals under the sorted transmission antenna combinations, and combining the threshold judgment to detect whether the transmission signals are reliable, once If there is a reliable detection transmission signal, it will be used as the final estimated transmission signal. Only when all detection transmission signals are unreliable, it is necessary to traverse all detection transmission signals and select the optimal one as the estimated transmission signal. The present invention can reduce the number of possible detection and transmission signals to be searched through the threshold judgment, thereby effectively reducing the detection complexity of the receiver, and obtaining better detection performance under the condition of lower complexity.

Description of drawings

Fig. 1 is a schematic diagram of the transmitting process of a generalized spatial modulation system transmitter;

Fig. 2 is a schematic diagram of a specific embodiment of a detection method for a receiver of a generalized spatial modulation system combined with threshold judgment according to the present invention.

detailed description

Specific embodiments of the present invention will be described below in conjunction with the accompanying drawings, so that those skilled in the art can better understand the present invention. It should be noted that in the following description, when detailed descriptions of known functions and designs may dilute the main content of the present invention, these descriptions will be omitted here.

In order to describe the present invention better, the terms used in the technical solution of the present invention and the generalized spatial modulation system transmitter are introduced first.

Transmitting antenna combination: refers to a group of randomly selected _NP roots among the N _T transmitting antennas of the transmitter. The _NP antennas selected for sending information symbols are called active transmitting antennas, and the unselected ones are called silent the transmitting antenna.

Channel matrix: Assuming that each transmit antenna and each receive antenna is a flat fading channel, the channel matrix of the MIMO system is:

Among them, _NR is the number of receiving antennas of the generalized spatial modulation system receiver, h _ij is the fading coefficient of the jth, _1≤j≤NT transmitting antenna to the i, _1≤i≤NR receiving antenna and obeys the mean value is 0 and a complex Gaussian distribution with variance 1.

Channel sub-matrix: refers to the channel sub-matrix H corresponding to the kth transmit antenna combination. _k refers to the sub-matrix composed of _NP column vectors corresponding to the _NP transmit antennas selected by the transmit antenna combination in the channel matrix H.

Equivalent Euclidean distance: equal to the Frobenius norm between the transmitted signal x and the received signal vector y after passing through the channel H, that is, the equivalent Euclidean distance d _Euc =||y-Hx|| _F .

Maximum likelihood criterion judgment: refers to selecting the signal vector that minimizes the equivalent Euclidean distance or its square value among the possible transmitted signals as the judgment result.

Theorem 1: Assuming that _NR is the number of receiving antennas of the system, σ ² is the variance of additive white Gaussian noise, if the transmitted signal is detected satisfy It is considered that the detection signal The detection is correct and reliable. For specific derivation, see FanWang, YongXiong, XiumeiYang, "Approximate ML Detection Based on MMSE for MIMO Systems," PIERSonline, vol.3, no.4, pp.475-480, 2007.

The transmitting antenna combination mapping table and the constellation mapping table are shared between the generalized space modulation system transmitter and receiver. Assume that the transmitter of the MIMO system has N _T transmitting antennas, from which N _P antennas are selected to send data, and there are a total of Antenna combinations, choose one of A design for the transmit antenna combination mapping table, Indicates rounding down. FIG. 1 is a schematic diagram of a transmitting process of a transmitter of a generalized spatial modulation system. The constellation mapping table can be set according to the actual situation of engineering applications. As shown in Figure 1, the transmitting process of the generalized spatial modulation system transmitter includes the following steps:

S101: Assume that one frame of digitized binary source data to be sent is u=(u ₁ ,u ₂ ,...,u _L ), where L is the frame size. In this example u=100111.

S102: Distribute the data, and part of the data Used to select the corresponding transmit antenna combination, another part of the data $u_2=(u_{l_1+1},u_2,\&Center\; Dot;\&Center\; Dot;\&Center\; Dot;,u_{L=l_1+l_2})$ , $l_2=L-l_1=N_P\·{\log }_2\left(m\right)$ Used to map modulation constellation symbols, where M is the modulation order. In this example, u ₁ =10, u ₂ =0111.

S103 _: Map the transmitting antenna combination according to u1. In this example, according to the transmit antenna combination mapping table, the transmit antenna corresponding to 10 is (1, 4).

S104: Map the modulation constellation symbols according to u ₂ to obtain the modulation constellation symbol data . In this example, according to the constellation mapping table, the modulation constellation symbol corresponding to 01 is -1+i, the modulation constellation symbol corresponding to 11 is 1+i, and the modulation constellation symbol data s=(-1+i, 1+i).

S105: Select the transmit antenna obtained in step S103 to transmit the modulated constellation symbol data obtained in step S104. In the selected transmit antenna combination, use the v, _1≤v≤NP transmit antenna to transmit the symbol s _v , then the transmitted signal can be expressed as , where (·) ^T represents the transpose of the matrix, the transmitted signal x has N _T elements, but only N _P non-zero values, and the position of the non-zero elements is corresponding to the selected active transmit antenna in the mapped combination index. The transmitted signal obtained in this example is x=(-1+i,0,0,1+i) ^T . The transmitter sends the signal x to the receiver.

Fig. 2 is a schematic diagram of a specific embodiment of a detection method for a receiver of a generalized spatial modulation system combined with threshold judgment according to the present invention. As shown in Figure 2, the generalized spatial modulation system receiver detection method combined with the threshold judgment of the present invention includes the following steps:

S201: Preprocessing the received signal:

The received signal of the receiver is denoted as y, and y is a column vector of N _R ×1, which can be expressed as:

y=Hx+n=H _k s _k +n

Among them, _NR is the number of receiving antennas, H is the channel matrix of the MIMO system, x is the transmitted signal of the transmitter of the generalized spatial modulation system, n is the additive white Gaussian noise with the mean value of 0 and the variance of ^σ2 , and s _k refers to the selected Modulated constellation symbol data sent under the k-th transmit antenna combination of .

The received signal y is preprocessed to obtain a preliminary equalized signal z of the received signal.

Preprocessing can directly use the conjugate transposition of the channel matrix for preprocessing, or use pseudo-inverse preprocessing, such as using the channel column vector or channel matrix for pseudo-inverse preprocessing, or use the minimum mean square error equalization matrix of the channel matrix Do preprocessing. In this embodiment, the channel matrix column vector is used for pseudo-inverse preprocessing, and the preliminary equalized signal vector z is:

Among them, h _j , j∈{1,2,…, _NT } represents the channel column vector corresponding to the jth transmitting antenna, represents the pseudo-inverse operation of a matrix, and (·) ^H represents the conjugate transpose of the matrix, and (·) ^T represents the transpose of the matrix.

S202: Calculate transmit antenna combination possibility weights:

Select the active transmitting antenna according to each combination in the transmitting antenna combination mapping table preset by the transmitter, and extract the corresponding elements in the equalized signal z to form a new vector z _k , k∈{1,2,…,N}, where N is The total number of transmit antenna combinations in the mapping table; the possibility weight w _{k of the corresponding transmit antenna combination is obtained according to z k .}

The possibility weight w _k can be obtained in two ways, one is to calculate the Frobenius norm of z _k or its square, that is, w _k = ||z _k || _F or Where ||·|| _F represents the Frobenius norm of the matrix or vector; the other can directly calculate the modulus of each element in z _k and sum them.

S203: Sorting the transmitting antenna combinations: sorting the transmitting antenna combinations according to the possibility weight w _k from large to small, and C _n represents the sorted nth transmitting antenna combination;

S204: Initially set n=1.

S205: Use the balanced detection method to detect and obtain the detection signal t _n corresponding to the nth transmitting antenna combination C _n after sorting, demodulate the detection signal t _n to obtain the detected constellation symbol data, and distribute the detected constellation symbol data to the transmitting antenna combination Each antenna in C _n gets the detection transmission signal

The balanced detection method can adopt all balanced detection algorithms applicable to the V-BLAST (Vertical-BellLabsLayeredSpace-Time, Vertical-Bell Labs Layered Space-Time) system. In this embodiment, a linear equalization detection method is adopted, including two commonly used algorithms: a zero-forcing (ZeroForcing, ZF) algorithm and a minimum mean square error (Minimum Mean Square Error, MMSE) algorithm.

When using the zero-forcing algorithm, the detection signal Where H _n represents the channel sub-matrix corresponding to the sorted transmit antenna combination C _n , and (·) ^-1 represents the inversion of the matrix.

When the minimum mean square error algorithm is used, the detection of the transmitted signal Where H _n represents the channel sub-matrix corresponding to the sorted transmit antenna combination C _n , I is the identity matrix of N _P × _NP , and (·) ^-1 represents the inversion of the matrix.

Detect sending signal Among them, Q( ) is a demodulation function, its function is to demodulate the detection signal t _n obtained by equalization detection, and obtain the corresponding detection constellation symbol data Then detect the constellation symbol data Sequentially assigned to the positions of the activated transmitting antennas under the transmitting antenna combination C _n , while the corresponding positions of the remaining silent transmitting antennas are set to 0, so as to obtain the detection transmission signal

S206: Judging and detecting the sending signal Is it reliable:

The decision threshold is V _theshold = N _R σ ² , if Then it shows that the detected sending signal is reliable, and the estimated sending signal Enter step S209; if unreliable, judge whether n<N, if n<N, enter step S207, if n=N, enter step S208;

S207: n=n+1, return to step S205 to judge the detection transmission signal corresponding to the next transmission antenna combination.

S208: Using the maximum likelihood criterion to select the optimal detection transmission signal from the detection transmission signals corresponding to the N transmission antenna combinations as the estimated transmission signal, that is

$\stackrel{<span\; class="notranslate">\; ~</span>}{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; =</span>{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; x</span>}}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; arg</span>}\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; \&Element;</span><span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; \&Center\; Dot;</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; \}</span>}{\mathrm{<span\; class="notranslate">\; min</span>}}{<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; h</span>}{\stackrel{<span\; class="notranslate">\; ^</span>}{\mathrm{<span\; class="notranslate">\; x</span>}}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; |</span>}_{\mathrm{<span\; class="notranslate">\; f</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$

The selection of optimally detected transmitted signals may also adopt the maximum a posteriori probability criterion.

S209: Send a signal according to the estimation The corresponding transmitting antenna combination and the mapping table of the modulation constellation are respectively demapped to restore the original binary bit information sequence.

Although the illustrative specific embodiments of the present invention have been described above, so that those skilled in the art can understand the present invention, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, As long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are included in the protection list.

Claims (8)

1. a generalized spatial modulation system receiver detection method in conjunction with threshold judgment, is characterized in that, comprises the following steps: S1: The received signal of the receiver is a column vector y=Hx+n of _NR × 1, where _NR is the number of receiving antennas, H is the channel matrix of the MIMO system, x is the transmitted signal of the transmitter of the generalized spatial modulation system, n is an additive white Gaussian noise with a mean value of 0 and a variance of ^σ2 ; the received signal y is preprocessed to obtain a preliminary equalized signal z of the received signal, and the preprocessing method adopts any one of the following three methods: using the channel matrix The conjugate transposition of the channel matrix is used for preprocessing; the channel matrix column vector or channel matrix is used for pseudo inverse preprocessing; the channel matrix is used for preprocessing with the minimum mean square error equalization matrix; S2: Select the active transmit antenna according to each combination in the preset transmit antenna combination mapping table, and extract the corresponding elements in the preliminary equalized signal z to form a new vector z _k , k=1,2,...,N, where N is the mapping The total number of transmit antenna combinations in the table; obtain the possibility weight w _{k of the corresponding transmit antenna combination according to z k ;} S3: Sort the transmit antenna combination from large to small according to the possibility weight w _k , and C _n represents the nth transmit antenna combination after sorting; S4: Use the balanced detection method to detect and obtain the detection signal t _n corresponding to the nth transmitting antenna combination C _n after sorting, demodulate the detection signal t _n to obtain the detected constellation symbol data, and distribute the detected constellation symbol data to the transmitting antenna combination Each antenna in C _n gets the detection transmission signal Judgment detection send signal Whether it is reliable, the decision threshold is V _theshold = N _R σ ² , once Where ||·|| _F means to find the Frobenius norm, then estimate the sent signal Go to step S5, otherwise continue to detect and judge a transmitting antenna combination; if all transmitting antenna combinations cannot be used then send a signal from all detections Select the optimal detected transmitted signal as the estimated transmitted signal Go to step S5; S5: Send a signal based on the estimate The corresponding transmitting antenna combination and the mapping table of the modulation constellation are respectively demapped to restore the original binary bit information sequence. 2 . The detection method for a generalized space modulation system receiver according to claim 1 , wherein the possibility weight w _k in the step S2 is the Frobenius norm of z _k or its square. 3 . 3. The detection method for a generalized spatial modulation system receiver according to claim 1, wherein the possibility weight w _k in the step S2 is the sum of modulus values of each element in z _k . 4. The generalized space modulation system receiver detection method according to claim 1, characterized in that the equalization detection method in the step S4 is a linear equalization detection method. 5. The generalized spatial modulation system receiver detection method according to claim 4, wherein the linear equalization detection method is a zero-forcing algorithm. 6. The generalized spatial modulation system receiver detection method according to claim 4, wherein the linear equalization detection method is a minimum mean square error algorithm. 7. The method for detecting a receiver of a generalized spatial modulation system according to any one of claims 1 to 6, wherein the optimally detected transmission signal is selected using a maximum likelihood criterion. 8. The method for detecting a receiver of a generalized space modulation system according to any one of claims 1 to 6, wherein the optimal detection transmission signal is selected using a maximum a posteriori probability criterion.