CN107968758B - System detection method based on orthogonal space modulation of MPSK signal - Google Patents

System detection method based on orthogonal space modulation of MPSK signal Download PDF

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CN107968758B
CN107968758B CN201711188447.6A CN201711188447A CN107968758B CN 107968758 B CN107968758 B CN 107968758B CN 201711188447 A CN201711188447 A CN 201711188447A CN 107968758 B CN107968758 B CN 107968758B
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mpsk
modulation
symbol
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constellation
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CN107968758A (en
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李兆玉
唐青青
马东亚
杨浩澜
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Chongqing University of Post and Telecommunications
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Abstract

The invention belongs to the technical field of wireless communication, in particular to a detection method of an orthogonal space modulation system based on MPSK signals; the method comprises the following steps: quantizing the MPSK signal constellation diagram by adopting a two-dimensional vector to obtain an MPSK quantization diagram; performing zero forcing once on a received signal to obtain a transmitting vector estimated value, and summing column elements of the transmitting vector estimated value to obtain a transmitting symbol estimated value; determining a quantization region of a transmission symbol estimation value in an MPSK quantization diagram, and judging a modulation symbol transmitted by a transmitting end as a constellation point of the quantization region; detecting a specific activated antenna index by using a spherical decoding SD according to the detected modulation symbol sent by the sending end; when the modulation symbol is detected, the transmission symbol estimation value can directly judge the modulation symbol transmitted by the transmitting end, and the detection of the modulation symbol has no relation with the modulation order, so that the search space is reduced, and the complexity is reduced; the SD detection adopted by the invention effectively reduces the number of search points and reduces the complexity of a receiver by reasonably selecting the search radius.

Description

System detection method based on orthogonal space modulation of MPSK signal
The technical field is as follows:
the invention belongs to the technical field of wireless communication, and relates to a method for detecting an orthogonal space modulation system based on an MPSK signal.
Background art:
since the early century, mobile communication services have been developed at a high speed, the number of communication users and the demand for mobile services have been gradually increased, and mobile communication has become an indispensable part of the daily life of people in modern society. With the rapid development and wide application of wireless communication technology, people have higher requirements on the transmission rate and communication reliability of a communication system, and the contradiction between limited communication resources and the increasing demand of communication services becomes a key problem to be solved urgently in the next generation of mobile communication.
With the increasing demand for wireless communication services, the demand for high-speed data transmission and high-frequency spectrum utilization of modern wireless communication is becoming higher and higher. The conventional single-antenna wireless communication system faces a serious challenge, and cannot meet the above requirements, even though the conventional diversity technology or smart antenna technology cannot solve the problem of high capacity and high reliability of the new generation wireless communication system. To solve this problem, multiple-input multiple-output (MIMO) technology has been developed. The MIMO technology implements multiplexing gain, diversity gain, and antenna gain in different forms by installing multiple transceiving antennas at a transceiving end on the premise of ensuring reliable transmission of a system, thereby greatly improving a data transmission rate of a wireless communication system and a capacity of the communication system, but the performance of the system is limited by inter-channel interference (ICI), inter-antenna synchronization (ISA), and a receiver detection algorithm with high complexity, and a Radio Frequency (RF) link of multiple antennas causes an increase in cost and complexity of the wireless communication system, which becomes a bottleneck for practical application of the MIMO system. Certainly, the conventional MIMO technology also adopts corresponding measures to solve the above problems, but the detection complexity at the receiving end is high, the cost overhead is high, and the multi-antenna synchronization is not easy to be ensured.
For the next generation mobile communication network, the energy efficiency of the communication system is gradually focused as the spectrum efficiency of the system is pursued. In order to improve the mobile data traffic, advanced transmission technologies and communication protocols have been studied to maximize the spectrum efficiency of the system, and the system throughput, the service quality, the practicability and the scalability are generally considered as the factors for designing the mobile network, so that the research on the energy consumption is neglected. With the recent introduction of green communication, the design of power efficiency and complexity of a system becomes a research hotspot, and achieving an effective balance between spectrum efficiency and energy efficiency becomes a key of the next generation wireless communication design. In the conventional technology, all transmission antennas are used for simultaneously transmitting data streams to obtain transmission diversity and multiplexing gain, so that the spectrum optimization of a system is realized, but the energy optimization of the system is not achieved. In addition, the inter-channel interference (ICI), inter-antenna synchronization (IAS) and complex demodulation algorithm of the receiver faced by the transmission system are all key technical problems to be solved urgently. For this reason, scholars such as r.mesleh have proposed a concept of Spatial Modulation (SM) in 2008.
The emergence of spatial modulation technology has solved some problems that the above-mentioned MIMO technology of multiple input multiple output exists to a certain extent, can avoid the question of inter-channel interference (ICI) and synchronism that the multiaerial launches effectively, and, in the spatial modulation system, the single radio frequency link is sufficient. The spatial modulation is a new MIMO modulation technology, which divides the input information bit into two parts to be mapped to the space antenna constellation diagram and the signal constellation diagram respectively, and can effectively improve the frequency band utilization rate of the system on the premise of not increasing the system bandwidth and the transmitting power. In SM systems, a single Radio Frequency (RF) link is allowed to be used, reducing the computational complexity at the receiving end. For the SM system, the number of the transmitting antennas and the modulation order can be flexibly configured on the premise of certain frequency band utilization rate.
In order to further improve the spectrum efficiency of the conventional spatial modulation system and the performance of the system, recently, Quadrature Spatial Modulation (QSM) is proposed. Compared with the traditional Spatial Modulation (SM) system, the Quadrature Spatial Modulation (QSM) system not only can improve the bit error performance (under the condition that the detection algorithm adopted by a receiving end is the same as the spectral efficiency of the system) and the spectral efficiency of the system, but also almost keeps all the advantages of the traditional spatial modulation system. At present, most detection algorithms for the orthogonal spatial Modulation system are based on a Multilevel Quadrature Amplitude Modulation (MQAM) method, and researches on a multilevel digital phase Modulation (MPSK) method are relatively few. The invention provides a detection algorithm based on MPSK signals by utilizing the characteristics of constellation points of an MPSK modulation mode. The traditional ML detection algorithm under the MPSK modulation mode needs to search all modulation symbols and activated antenna combinations exhaustively, so that the correct modulation symbols and activated antenna combinations are detected; the complexity of the receiver detection algorithm is extremely high. The invention aims to solve the problem of extremely high complexity of the traditional ML detection algorithm and aims to find a detection algorithm with compromise performance and complexity.
The invention content is as follows:
in view of this, the present invention provides a Quadrature Spatial Modulation (QSM) system detection method based on an MPSK signal, which specifically includes the following technical solutions:
a Quadrature Spatial Modulation (QSM) system detection method based on an MPSK signal, the method comprising:
s1, quantizing the MPSK signal constellation diagram by adopting a two-dimensional vector to obtain an MPSK quantization diagram;
s2, carrying out zero forcing once on the received signal y to obtain the estimated value of the transmission vector
Figure BDA0001480556410000031
To the above
Figure BDA0001480556410000032
Summing the column elements to obtain the estimated value of the transmitted symbol
Figure BDA0001480556410000039
And expressed in polar form, and then will
Figure BDA0001480556410000033
Quantizing into an MPSK constellation quantization diagram;
s3, quantizing characteristics of graph according to MPSK constellation, quantizing boundary and
Figure BDA0001480556410000034
of a polar angle of (a) to obtain
Figure BDA0001480556410000035
A corresponding specific quantization region in the MPSK constellation quantization diagram; the constellation points in the quantization region are determined as modulation symbols sent by the sending end;
and S4, determining the modulation symbol sent by the sending end according to the constellation point in the quantization region obtained in S3, searching a sending antenna combination corresponding to the modulation symbol sent by the sending end by using the sphere decoding SD, and detecting a specific activated antenna index, namely a specific activated antenna serial number, of the modulation symbol sent by the sending end.
Preferably, said performing zero forcing once on the received signal y yields the transmit vector estimate
Figure BDA0001480556410000036
Can be expressed by the formula:
Figure BDA0001480556410000037
wherein H+Representing the pseudo-inverse of the channel matrix H. Will be provided with
Figure BDA0001480556410000038
The column elements in (1) are added and summed to obtain the estimated value of the transmitted symbol
Figure BDA0001480556410000041
Written in polar coordinate form
Figure BDA0001480556410000042
Where θ represents a polar angle and r represents a polar axis.
Preferably, the characteristics of the quantization map, the quantization boundaries and
Figure BDA0001480556410000043
of a polar angle of (a) to obtain
Figure BDA0001480556410000044
The corresponding specific quantization region in the MPSK constellation quantization diagram includes: according to the formula
Figure BDA0001480556410000045
Calculating an estimated value of a transmitting symbol phase; then according to the formula
Figure BDA0001480556410000046
Calculate out the
Figure BDA0001480556410000047
Corresponding transmission symbol
Figure BDA0001480556410000048
The transmission symbol
Figure BDA0001480556410000049
Namely the modulation symbol sent by the sending end;
wherein the content of the first and second substances,
Figure BDA00014805564100000410
the estimated value representing the quantization region, i.e. the second
Figure BDA00014805564100000411
A quantization area is defined as a region of a region,
Figure BDA00014805564100000412
Figure BDA00014805564100000413
an estimate of the phase of a constellation point is represented,
Figure BDA00014805564100000414
round (a) represents an integer nearest to a, M represents a constellation point modulation order, mod () represents modulo,
Figure BDA00014805564100000415
representing the phase, x, of the ith constellation pointiIndicating the transmission symbol corresponding to the ith constellation point. It can be seen that the modulation symbol transmitted by the transmitting end is independent of the size of the constellation diagram of the signal space.
Further, determining, according to constellation points in the quantization region obtained in S3, that is, determining a modulation symbol sent by the sending end, searching for a sending antenna combination corresponding to the modulation symbol sent by the sending end by using sphere decoding SD, and detecting a specific activated antenna index of the modulation symbol sent by the sending end includes:
activating two antennas to respectively transmit a real part and an imaginary part of a modulation symbol in each time slot in an orthogonal space modulation system, traversing two conditions, traversing corresponding transmission vectors traversed by the two conditions by adopting a spherical decoding SD, and further detecting the serial number of the activated antenna; the two case traversal includes: the real part and the imaginary part of the modulation symbol are transmitted by the antenna corresponding to the same activated antenna index; the real part and the imaginary part of the modulation symbol are respectively transmitted by the antennas corresponding to different activated antenna indexes;
the method specifically comprises the following steps: transmitting symbols
Figure BDA00014805564100000416
Expressed as:
Figure BDA00014805564100000417
finding out all the transmission vectors corresponding to the transmission symbols in a symbol table, and performing SD search of the activated antenna index, wherein the SD search comprises the following steps:
Figure BDA00014805564100000418
wherein the content of the first and second substances,
Figure BDA00014805564100000419
represents the estimated active antenna index and,
Figure BDA00014805564100000420
respectively representing the transmission symbols detected in the previous step
Figure BDA0001480556410000051
Real and imaginary parts of (c).
Figure BDA0001480556410000052
Denoted as antenna index; argmin [. C]When the minimum value is expressed, the value of the independent variable is obtained; y isr、
Figure BDA0001480556410000053
And
Figure BDA0001480556410000054
respectively representing a received vector y, a matrix
Figure BDA0001480556410000055
Sum matrix
Figure BDA0001480556410000056
The r-th element of (1);
Figure BDA0001480556410000057
is to calculate the Euclidean distance
Figure BDA0001480556410000058
Is the number of searches, i.e. the search depth, C0Indicating the initial radius of the search range.
Preferably, the initial radius of the search range
Figure BDA0001480556410000059
α is a formula
Figure BDA00014805564100000510
α is a constant for a particular receive antenna.
Figure BDA00014805564100000511
Figure BDA00014805564100000512
Wherein C is a point set consisting of all transmission symbols X and antenna indexes L within the radius sphere. (s) is a gamma function, and
Figure BDA00014805564100000513
gamma (s, x) is the lower partial(s) gamma function,
Figure BDA00014805564100000514
is a very small constant, representing the probability of detection error, typically 10-6。
It is worth mentioning that, for different active antennas and constellation symbols,
Figure BDA00014805564100000515
different, each search may require computation to be performed
Figure BDA00014805564100000516
Next time
Figure BDA00014805564100000517
It may also be necessary only once, and therefore,
Figure BDA00014805564100000518
in the range of
Figure BDA00014805564100000519
Thus, according to the above scheme, the present invention detects the transmission symbol
Figure BDA00014805564100000520
And activating the antenna combination.
Description of the drawings:
FIG. 1 is an orthogonal space system model;
FIG. 2 is a flowchart of a method for detecting an orthogonal spatial modulation system based on MPSK signals according to the present invention;
fig. 3 is a diagram illustrating quantization of 8PSK constellation;
the specific implementation mode is as follows:
in order to make the objects, technical solutions and advantages of the present invention more clearly and completely apparent, the technical solutions in the embodiments of the present invention are described below with reference to the accompanying drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention will be further described with reference to the following detailed description of embodiments and with reference to the accompanying drawings in which:
preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
FIG. 1 is a diagram of a quadrature spatial modulation system model, as shown in FIG. 1, NtAnd NrRespectively representing the number of transmitting antennas and the number of receiving antennas, the inventionThe spectral efficiency of an orthogonal spatial modulation system can be expressed in terms of the equation m-log2(Nt 2M) represents, wherein M represents a constellation point modulation order; wherein log2(M) bits are used to modulate signal constellation symbols, otherwise log2(Nt 2) Bits are used to control the index of the active antenna for transmitting the real and imaginary parts of the modulated symbol x, respectively, and cosine carrier is used to transmit the real part
Figure BDA0001480556410000061
Sine carrier transmit imaginary part
Figure BDA0001480556410000062
The actual transmitted modulation symbol may be expressed as:
Figure BDA0001480556410000063
however, in spatial modulation techniques, only one antenna is activated per time slot for transmission
Figure BDA0001480556410000064
And
Figure BDA0001480556410000065
thus, the number of bits transmitted per slot in orthogonal spatial modulation is increased by log compared to spatial modulation2(Nt). Because the sine and cosine carriers are orthogonal to each other, inter-channel interference is not a concern in quadrature spatial modulation systems. Since the number of antennas activated per time slot is at most 2, the requirement for synchronization between antennas is also reduced. In the orthogonal spatial modulation technique, a spatial separator may be used to assign the real and imaginary parts of one signal to the corresponding active antennas, respectively.
Preferably, with NtFor example, 2, a specific mapping principle of the orthogonal spatial modulation system is specifically introduced, and the mapping principle is also applicable to the number of other transmitting antennas. Suppose that a sub-data block transmitted in a particular time slot is
Figure BDA0001480556410000066
QPSK modulation is used. The specific implementation of the orthogonal spatial modulation system is as follows: rear log2The (M) bits 10 modulate the QPSK symbol x ═ 1-j. The symbols are further decomposed into real parts
Figure BDA0001480556410000067
And imaginary part
Figure BDA0001480556410000068
Front log2(Nt) One bit 1 controls the active antenna index,
Figure BDA0001480556410000069
for transmitting real part
Figure BDA00014805564100000610
The real transmit vector may be represented as
Figure BDA00014805564100000611
Figure BDA00014805564100000612
0 in (2) indicates that the transmitting antenna corresponding to the position is in a silent state, no information is transmitted, and only the real part of the modulation symbol is transmitted by activating the antenna index 2. Log after log2(Nt) One bit 0 controls the active antenna index
Figure BDA0001480556410000071
For transmitting imaginary part
Figure BDA0001480556410000072
The imaginary transmit vector may be represented as
Figure BDA0001480556410000073
Then will be
Figure BDA0001480556410000074
And
Figure BDA0001480556410000075
adding up to obtain the transmission vector
Figure BDA0001480556410000076
s is passed through one Nr× 1 has a mean value of 0 and a variance of σ2Accompanied by additive white Gaussian noise
Figure BDA0001480556410000077
N of (A)r×NtThe dimension channel H is transmitted.
Element H of the complex channel matrix Hi,jRepresenting the channel gain between the jth transmit antenna and the ith receive antenna,
Figure BDA0001480556410000078
represents H of
Figure BDA0001480556410000079
And (4) columns. The elements of the channel matrix H are assumed to be independent identically distributed complex gaussian random variables with a mean of 0 and a variance of 1.
The received signal may be expressed as:
Figure BDA00014805564100000710
a specific mapping when the number of transmission bits of the orthogonal spatial modulation system is 4 bits is shown in table 1,
TABLE 1 Quadrature spatial modulation 4-bit mapping table
Figure BDA00014805564100000711
As shown in fig. 2, the MPSK signal-based detection algorithm of an orthogonal spatial modulation (QSM) system of the present invention includes the following steps:
s1, quantizing the MPSK signal constellation diagram by adopting a two-dimensional vector to obtain an MPSK quantization diagram;
s2, carrying out zero forcing once on the received signal y to obtain the estimated value of the transmission vector
Figure BDA0001480556410000081
To the above
Figure BDA0001480556410000082
Summing the column elements to obtain the estimated value of the transmitted symbol
Figure BDA0001480556410000083
And expressed in polar form, and then will
Figure BDA0001480556410000084
Quantizing into an MPSK constellation quantization diagram;
s3, quantizing characteristics of graph according to MPSK constellation, quantizing boundary and
Figure BDA00014805564100000810
of a polar angle of (a) to obtain
Figure BDA00014805564100000811
A corresponding specific quantization region in the MPSK constellation quantization diagram; the constellation points in the quantization region are determined as modulation symbols sent by the sending end;
and S4, determining the modulation symbol sent by the sending end according to the constellation point in the quantization region obtained in S3, searching a sending antenna combination corresponding to the modulation symbol sent by the sending end by using the sphere decoding SD, and detecting a specific activated antenna index, namely a specific activated antenna serial number, of the modulation symbol sent by the sending end.
Further, preferably, the two-dimensional vector quantization of the MPSK constellation includes: setting the initial phase to be 0, and the amplitude of the constellation point to be 1, the ith constellation point in the MPSK constellation diagram may be represented as:
Figure BDA0001480556410000085
wherein the content of the first and second substances,
Figure BDA0001480556410000086
the phase of i constellation points is represented, and M represents the modulation order of the constellation points.
Further, it is preferable that the MPSK constellation may have different representations due to different initial phases, but its constellation points are necessarily located on the same circle, and the center of the circle is at the origin of coordinates. Aiming at the MPSK signal, the two-dimensional vector quantization can be carried out on an MPSK constellation diagram from the perspective of the two-dimensional vector quantization; the MPSK constellation quantization is specifically as follows:
preferably, in 8PSK as an example, as shown in fig. 3, the dotted line indicates the limit of signal quantization and demodulation on the two-dimensional plane, the black dot indicates the constellation point, and β indicates the transmission symbol estimation value
Figure BDA00014805564100000812
And transmitting the symbol
Figure BDA0001480556410000087
The included angle therebetween. Assuming that the initial phase is 0 and the amplitude of the constellation point is 1, the ith constellation point in the MPSK constellation diagram can be represented as:
Figure BDA0001480556410000088
wherein the content of the first and second substances,
Figure BDA0001480556410000089
and the estimated value of the phase of the i constellation points is shown, and M represents the modulation order of the constellation points.
The MPSK signal-based orthogonal spatial modulation system detection method as claimed in claim 1, wherein the zero forcing is performed once on the received signal y to obtain a transformed transmitted vector estimation value
Figure BDA0001480556410000091
Can be expressed by the formula:
Figure BDA0001480556410000092
wherein H+Representing the pseudo-inverse of the channel matrix H. Will be provided with
Figure BDA0001480556410000093
The column elements in (1) are added and summed to obtain the estimated value of the transmitted symbol
Figure BDA0001480556410000094
Written in polar coordinate form
Figure BDA0001480556410000095
θ represents a polar angle, and r represents a polar axis.
Preferably, the characteristics of the quantization map, the quantization boundaries and
Figure BDA0001480556410000096
of a polar angle of (a) to obtain
Figure BDA0001480556410000097
The corresponding specific quantization region in the MPSK constellation quantization diagram includes: according to the formula
Figure BDA0001480556410000098
Detecting a specific transmission symbol; according to the formula
Figure BDA0001480556410000099
Calculate out the
Figure BDA00014805564100000910
Corresponding transmission symbol
Figure BDA00014805564100000911
The transmission symbol
Figure BDA00014805564100000912
Namely the modulation symbol sent by the sending end;
preferably, the estimated value of the phase of the constellation point
Figure BDA00014805564100000913
Can be composed of
Figure BDA00014805564100000914
Is calculated to obtain
Figure BDA00014805564100000915
Figure BDA00014805564100000916
The angle () function represents fetch
Figure BDA00014805564100000917
The polar angle of (1). So that the estimate of the phase can be calculated by the above formula as long as the received signal y is obtained. After the phase estimation, according to the formula
Figure BDA00014805564100000918
Calculating the specific transmitting symbol transmitted by the transmitting end
Figure BDA00014805564100000919
Wherein the estimated value of the constellation point phase
Figure BDA00014805564100000920
Is based on
Figure BDA00014805564100000921
Is calculated by
Figure BDA00014805564100000922
Is also based on
Figure BDA00014805564100000923
The obtained theta is obtained after corresponding transformation is carried out according to the received signal y, so that the estimated value of the phase of the constellation point can be obtained as long as the received signal y is obtained, and after the estimated value of the phase is calculated, the specific modulation symbol sent by the sending end knows which one is obtained;
further, the modulation symbol sent by the sending end is determined according to the constellation point in the quantization region obtained in S3, and the sending antenna combination corresponding to the modulation symbol sent by the sending end is searched by using the sphere decoding SD, so as to detect the specific activated antenna index of the modulation symbol sent by the sending end, that is, after the modulation symbol is detected, the specific sending antenna of the sending end is further detected by using the sphere decoding SD, the process is as follows:
activating two antennas to respectively transmit a real part and an imaginary part of a modulation symbol in each time slot in an orthogonal space modulation system, traversing two conditions, traversing corresponding transmission vectors traversed by the two conditions by adopting a spherical decoding SD, and further detecting the serial number of the activated antenna; the two case traversal includes: the real part and the imaginary part of the modulation symbol are transmitted by the antenna corresponding to the same activated antenna index; the real part and the imaginary part of the modulation symbol are respectively transmitted by the antennas corresponding to different activated antenna indexes;
the method specifically comprises the following steps: transmitting symbols
Figure BDA0001480556410000101
Expressed as:
Figure BDA0001480556410000102
finding out all the transmission vectors corresponding to the transmission symbols in a symbol table, and performing SD search of the activated antenna index, wherein the SD search comprises the following steps:
Figure BDA0001480556410000103
wherein the content of the first and second substances,
Figure BDA0001480556410000104
represents the estimated active antenna index and,
Figure BDA0001480556410000105
respectively representing transmitted symbols
Figure BDA0001480556410000106
Real and imaginary parts of (c).
Figure BDA0001480556410000107
Denoted as antenna index, yr、
Figure BDA0001480556410000108
And
Figure BDA0001480556410000109
respectively representing a received vector y, a matrix
Figure BDA00014805564100001010
Sum matrix
Figure BDA00014805564100001011
The r-th element of (1);
Figure BDA00014805564100001012
is to calculate the Euclidean distance
Figure BDA00014805564100001013
Number of times, i.e. search depth, C0Indicating the initial radius of the search range.
Preferably, the first and second liquid crystal materials are,
Figure BDA00014805564100001014
α is a formula
Figure BDA00014805564100001015
α is a constant for a particular receive antenna.
Figure BDA00014805564100001016
Figure BDA00014805564100001017
Wherein C is a point set consisting of all transmission symbols X and antenna indexes L within the radius sphere. (s) is a gamma function, and
Figure BDA00014805564100001018
gamma (s, x) is the lower incomplete(s) a gamma function of the gamma of the object,
Figure BDA00014805564100001019
is a very small constant, representing the probability of detection error, typically 10-6。
It is worth mentioning that, for different active antennas and constellation symbols,
Figure BDA00014805564100001020
different, each search may require computation to be performed
Figure BDA00014805564100001021
Next time
Figure BDA00014805564100001022
It may also be necessary only once, and therefore,
Figure BDA00014805564100001023
in the range of
Figure BDA00014805564100001024
Thus, according to the above-described method, the transmission symbol is detected
Figure BDA0001480556410000111
And activating the antenna combination.
The spherical decoding SD detection has the advantages that the SD detection avoids exhaustive retrieval caused by ML detection by reasonably selecting the search radius, effectively reduces the number of search points, and greatly reduces the complexity of a receiver compared with the ML detection.
Finally, it is noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims.

Claims (7)

1. A detection method of an orthogonal space modulation system based on MPSK signals is characterized in that: the method comprises the following steps:
s1, quantizing the MPSK signal constellation diagram by adopting a two-dimensional vector to obtain an MPSK quantization diagram;
s2, carrying out zero forcing once on the received signal y to obtain the estimated value of the transmission vector
Figure FDA00024651800000000112
To the above
Figure FDA00024651800000000116
Summing the column elements to obtain the estimated value of the transmitted symbol
Figure FDA00024651800000000113
And expressed in polar coordinate form, will
Figure FDA00024651800000000111
Quantizing into an MPSK constellation quantization diagram;
s3, according to the characteristics of MPSK constellation quantization diagram, namely, each constellation point is located on the same circle, and the circle center of the circle is located on the characteristics of the origin of coordinates, the quantization boundary and
Figure FDA00024651800000000115
of a polar angle of (a) to obtain
Figure FDA00024651800000000114
A corresponding specific quantization region in the MPSK constellation quantization diagram; the constellation points in the specific quantization region are determined as modulation symbols sent by the sending end;
according to the formula
Figure FDA0002465180000000011
Calculating an estimated value of a transmitting symbol phase; then according to the formula
Figure FDA0002465180000000012
Calculate out the
Figure FDA0002465180000000013
Corresponding transmission symbol
Figure FDA0002465180000000014
The transmission symbol
Figure FDA0002465180000000015
Namely the modulation symbol sent by the sending end;
wherein the content of the first and second substances,
Figure FDA0002465180000000016
the estimated value representing the quantization region, i.e. the second
Figure FDA0002465180000000017
A quantization area is defined as a region of a region,
Figure FDA0002465180000000018
Figure FDA0002465180000000019
round (a) represents an integer nearest to a, M represents a constellation point modulation order, mod () represents modulo,
Figure FDA00024651800000000110
representing the phase, x, of the ith constellation pointiRepresenting a transmission symbol corresponding to the ith constellation point;
s4, obtaining the modulation symbol sent by the sending end according to S3; and searching a transmitting antenna combination corresponding to the modulation symbol transmitted by the transmitting end by using the spherical decoding SD, and detecting a specific activated antenna index, namely a specific activated antenna serial number, of the modulation symbol transmitted by the transmitting end.
2. The MPSK signal-based orthogonal spatial modulation system detection method as claimed in claim 1, wherein the sampling is performed by using a pulse-width modulation (PSK) signalThe MPSK constellation diagram is quantized by using the two-dimensional vector, and the MPSK quantization diagram is obtained by the following steps: setting the initial phase to be 0, and the amplitude of the MPSK constellation point to be 1, then the ith constellation point x in the MPSK constellation diagramiExpressed as:
Figure FDA0002465180000000021
wherein the content of the first and second substances,
Figure FDA0002465180000000022
the phase of the ith constellation point is shown, and M represents the modulation order of the constellation point.
3. The MPSK signal-based orthogonal spatial modulation system detection method as claimed in claim 1, wherein the zero forcing is performed once on the received signal y to obtain the estimated value of the transmission vector
Figure FDA0002465180000000023
Can be expressed by the formula:
Figure FDA0002465180000000024
wherein H+Representing the pseudo-inverse of the channel matrix H.
4. The MPSK signal-based orthogonal spatial modulation system detection method as claimed in claim 1, wherein the pair
Figure FDA00024651800000000211
Summation of column elements
Figure FDA0002465180000000025
The method comprises the following steps: will be provided with
Figure FDA00024651800000000212
The column elements in (1) are added and summed to obtain the estimated value of the transmitted symbol
Figure FDA0002465180000000026
Written in polar coordinate form
Figure FDA0002465180000000027
Theta represents a polar angle, r represents a polar axis, and theta is more than or equal to 0 and less than or equal to 2 pi.
5. The method according to claim 1, wherein the determining that the constellation point in the quantization region obtained according to S3 is the modulation symbol sent by a sending end, searching for a sending antenna combination corresponding to the modulation symbol sent by the sending end by using sphere decoding SD, and detecting the specific active antenna index of the modulation symbol sent by the sending end comprises:
activating two antennas for each time slot in an orthogonal space modulation system to respectively transmit a real part and an imaginary part of a modulation symbol, wherein traversing is divided into two conditions, and traversing corresponding transmission vectors traversed by the two conditions by adopting an SD (secure digital) criterion so as to detect the serial number of the activated antenna; the two case traversal includes: the real part and the imaginary part of the modulation symbol are transmitted by the antenna corresponding to the same activated antenna index; the real part and the imaginary part of the modulation symbol are respectively transmitted by the antennas corresponding to different activated antenna indexes;
the method specifically comprises the following steps: transmitting symbols
Figure FDA0002465180000000028
Expressed as:
Figure FDA0002465180000000029
finding the transmitted symbol in a symbol table
Figure FDA00024651800000000210
Performing SD search of the active antenna index for all corresponding transmission vectors, that is,:
Figure FDA0002465180000000031
wherein the content of the first and second substances,
Figure FDA0002465180000000032
represents the estimated active antenna index and,
Figure FDA0002465180000000033
respectively represent the transmitted symbols
Figure FDA0002465180000000034
The real and imaginary parts of (c);
Figure FDA0002465180000000035
denoted as antenna index; argmin [. C]When the minimum value is expressed, the value of the independent variable is obtained; n is a radical oftIndicates the number of transmitting antennas, yr、
Figure FDA0002465180000000036
And
Figure FDA0002465180000000037
respectively representing a received vector y, a matrix
Figure FDA0002465180000000038
Sum matrix
Figure FDA0002465180000000039
The (c) th element of (a),
Figure FDA00024651800000000310
is to calculate the Euclidean distance
Figure FDA00024651800000000311
Is the number of times of search, NrIndicating the number of receiving antennas, C0Indicating the initial radius of the search range.
6. The MPSK signal-based orthogonal spatial modulation system detection method as claimed in claim 5, wherein the initial radius C of the search range0Comprises the following steps:
Figure FDA00024651800000000312
wherein α is a formula
Figure FDA00024651800000000313
The solution of (1); (s) is a gamma function, and
Figure FDA00024651800000000314
gamma (s, x) is the lower partial(s) gamma function,
Figure FDA00024651800000000315
constant, α constant for a particular receive antenna,
Figure FDA00024651800000000316
representing the noise power when the transmission power is 1.
7. The MPSK signal-based orthogonal spatial modulation system detection method as claimed in claim 5, wherein the MPSK signal-based orthogonal spatial modulation system detection method is characterized in that
Figure FDA00024651800000000317
The method specifically comprises the following steps:
Figure FDA00024651800000000318
wherein, C is a point set composed of all the transmitting symbols X and the antenna index L in the radius sphere, and when argmax [. cndot ] represents the maximum value, the value of the independent variable is obtained.
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