CN114050853B - Multi-user MIMO transmission method based on joint non-orthogonal codebook and pre-coding design - Google Patents

Multi-user MIMO transmission method based on joint non-orthogonal codebook and pre-coding design Download PDF

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CN114050853B
CN114050853B CN202111333460.2A CN202111333460A CN114050853B CN 114050853 B CN114050853 B CN 114050853B CN 202111333460 A CN202111333460 A CN 202111333460A CN 114050853 B CN114050853 B CN 114050853B
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codebook
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CN114050853A (en
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于启月
杨成瑶
王屹
李江炫
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Harbin Institute of Technology
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0452—Multi-user MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting

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Abstract

The invention discloses a multi-user MIMO transmission method based on a combined non-orthogonal codebook and precoding design, and relates to a multi-user MIMO transmission method. Book (I)The invention aims to solve the problems of large resource consumption, low spectrum efficiency, low reliability caused by multi-user interference and the like of the conventional system in a multi-user scene. The process is as follows: step one, establishing a downlink MU-MIMO system of a joint non-orthogonal space-time codebook; the MIMO is multiple input multiple output; MU is multiuser; step two, setting a non-orthogonal space-time codebook based on CLST based on the step one; the CLST is a cyclic layered space-time structure; step three, performing joint precoding and signal detection based on the step two; step four, eliminating the signal obtained by the detection in the step three by adopting a Viterbi decoder
Figure DDA0003349661260000011
To obtain the final detection signal. The invention is used in the field of multi-user MIMO transmission.

Description

Multi-user MIMO transmission method based on joint non-orthogonal codebook and precoding design
Technical Field
The invention belongs to the technical field of communication signal design and detection, and particularly relates to a design of a multi-user MIMO transmission scheme combining a non-orthogonal codebook and precoding, which is suitable for the conditions of user codebook design, combined precoding and signal detection, multi-user interference elimination and the like in a downlink multi-user MIMO system.
Background
With the continuous advance of informatization, mobile devices are more popular, and 5G and beyond 5G require more user access, higher transmission rate and higher reliability. In such a scenario, a large amount of overhead is introduced if a conventional Orthogonal Multiple Access scheme (OMA) is adopted. Non-orthogonal Multiple Access (NOMA), which is an Access method capable of realizing large-scale Access and high spectrum efficiency, has been regarded as a key technology in 3GPP, and has great potential.
A Multiple Input Multiple Output (MIMO) system can utilize space resources to improve spectral efficiency and transmission rate, and does not occupy additional time-frequency resources, so that combining MIMO with NOMA enables a base station to serve Multiple users, improves the performance of a wireless communication system, and meets the requirements of large connection, high rate, high spectral efficiency, high reliability, and the like.
Disclosure of Invention
The invention aims to solve the problems of high resource consumption, low spectrum efficiency, low reliability caused by multi-user interference and the like of the conventional system in a multi-user scene, and provides a multi-user MIMO transmission method based on joint non-orthogonal codebook and pre-coding design.
The specific process of the multi-user MIMO transmission method based on the combined non-orthogonal codebook and precoding design is as follows:
step one, establishing a downlink MU-MIMO system of a joint non-orthogonal space-time codebook;
the MIMO is multiple input multiple output; MU is multiuser;
step two, setting a non-orthogonal space-time codebook based on CLST based on the step one;
the CLST is a cyclic layered space-time structure;
step three, performing combined precoding and signal detection based on the step two;
step four, eliminating the signal obtained by the detection in the step three by adopting a Viterbi decoder
Figure BDA0003349661240000011
To obtain the final detection signal.
The invention has the beneficial effects that:
the beneficial effects of the invention are: the invention provides a downlink multi-user MIMO transmission design scheme combining a non-orthogonal codebook and precoding, which better exerts the characteristics of a space-time structure, improves the error code performance, improves the spectrum efficiency and has low resource consumption in a multi-user scene by respectively designing the non-orthogonal space-time codebook, a combined precoding and signal detection algorithm and an iterative decoding algorithm, thereby providing a favorable support scheme for the requirements of large connection, high speed, high reliability and the like in 5G and beyond 5G scenes.
The multi-user MIMO transmission scheme based on the combined non-orthogonal codebook and precoding design provided by the invention better exerts the characteristics of a space-time structure, simultaneously provides a precoding and signal detection algorithm based on the combined design, designs an iterative decoding algorithm based on a Viterbi decoder, improves the error code performance of the system, and solves the problems of large resource consumption, low spectrum efficiency, low reliability brought by multi-user interference and the like of the conventional system in a multi-user scene.
Drawings
FIG. 1 is a diagram of a transmitting end model of a downlink MU-MIMO system combining non-orthogonal space-time codebooks in accordance with an embodiment of the present invention, b u Is the original information, c is the encoded vector,
Figure BDA0003349661240000021
is n th j The coded vector corresponding to each space-time block,
Figure BDA0003349661240000022
is at the n-th j N on each space-time block t The transmit symbols on the root transmit antenna are,
Figure BDA0003349661240000023
is at the n-th j N on the Tth time slot of each space-time block t Transmitting symbols on the root transmitting antenna, W 1 In order to pre-code the sequence of data,
Figure BDA0003349661240000024
is a transmission matrix;
FIG. 2 is a diagram of a model of a receiving end of a downlink MU-MIMO system combining non-orthogonal space-time codebooks in accordance with the present invention,
Figure BDA0003349661240000025
for the u-th user at the n-th j Received signal of space-time block, W is precoding sequence, V u For the detection matrix, H u Is a channel matrix between the u-th user receiving end and the transmitting end, F is a mapping,
Figure BDA0003349661240000026
is an estimated value obtained by i-1 iterations of the original information,
Figure BDA0003349661240000027
for the ith iteration the nth user j On a space-time blockThe detected signal of (a) is,
Figure BDA0003349661240000028
for the ith iteration the u user is at the n j An estimate of the transmitted signal over a number of space-time blocks,
Figure BDA0003349661240000029
for the ith iteration the u user is at the n j Transmitting matrix over space-time blocks
Figure BDA00033496612400000210
Is determined by the estimated value of (c),
Figure BDA00033496612400000211
for the ith iteration pair estimate
Figure BDA00033496612400000212
The vector after the de-mapping is performed,
Figure BDA00033496612400000213
for the ith iteration pair
Figure BDA00033496612400000214
The value of the buffer(s) of (c),
Figure BDA00033496612400000215
is composed of
Figure BDA00033496612400000216
Vectors after viterbi decoding;
FIG. 3a is a codebook diagram of a Non-overlapping structure (NOS) CLST space-time codebook structure according to the present invention;
FIG. 3b is a codebook diagram of the CLST space-time codebook structure with an Overlapping Structure (OS) according to the present invention;
FIG. 3c is a codebook diagram of a Trailing Structure (TS) CLST space-time codebook structure according to the present invention;
FIG. 4 is a graph of the performance of a non-orthogonal space-time codebook, BER is the bit error rate, E b Is energy per bit，N 0 Is a single-sided power spectral density of white gaussian noise;
FIG. 5 is a graph comparing the complexity of different precoding algorithms;
FIG. 6 is a comparison of Min-SMSE for different precoding algorithms, where Min-SMSE is the minimum and mean square error;
fig. 7 is a graph of performance of an iterative interference cancellation decoding algorithm based on a viterbi decoder.
Detailed Description
The first embodiment is as follows: the specific process of the multi-user MIMO transmission method based on the combined non-orthogonal codebook and precoding design in the embodiment is as follows:
the invention researches the codebook design, the joint pre-coding and signal detection and the iterative decoding scheme by establishing the receiving and transmitting system model of the downlink MU-MIMO system of the joint non-orthogonal space-time codebook, and provides the overall design scheme of the receiving and transmitting terminal.
Step one, establishing a downlink MU-MIMO system of a joint non-orthogonal space-time codebook;
the MIMO is multiple input multiple output; MU is multiuser;
step two, setting a non-orthogonal space-time codebook based on CLST based on the step one;
the CLST is a cyclic layered space-time structure;
step three, performing joint precoding and signal detection based on the step two;
step four, eliminating the signal detected in step three by using Viterbi decoder
Figure BDA0003349661240000031
To obtain the final detection signal.
The second embodiment is as follows: the difference between the present embodiment and the first embodiment is that, in the first step, a downlink MU-MIMO system combining non-orthogonal space-time codebooks is established; the specific process is as follows:
in the system design, a sending end comprises modules of multi-user channel coding, space-time codebook mapping, precoding and the like, and a receiving end comprises modules of detection, multi-user detection, demapping, viterbi decoding, iterative decoding and the like. The original information of all users is mapped into space-time code word vectors after multi-user coding, a transmitting matrix obtained after pre-coding reaches a receiving end after passing through a Rayleigh flat fading channel, and a received signal is processed by a detection matrix and then is subjected to multi-user detection, de-mapping and iterative decoding to obtain a detection result.
The method comprises the following steps: as shown in FIG. 1, the downlink MU-MIMO system of the joint non-orthogonal space-time codebook has a total of U users, wherein the original information b of the user U u Are binary bit streams of length K; u is more than or equal to 1 and less than or equal to U;
original information b of user u Carrying out multi-user channel coding to obtain a coded vector c with the length of N;
dividing the encoded vector c into N J Each block comprising J bits, and then mapping each block to a length of T.N by a space-time codebook F t Space-time codeword vector of
Figure BDA0003349661240000032
Wherein T represents the number of time slots of the space-time resource block, N t Representing the number of transmit antennas;
passing the space-time codeword vector through a precoding sequence W = [ W (1), …, W (T), …, W (T)]Obtaining a transmit matrix
Figure BDA0003349661240000041
Wherein
Figure BDA0003349661240000042
The first step is: transmitting matrix of each user obtained by the steps one by one
Figure BDA0003349661240000043
The signal reaches a receiver through a Rayleigh flat fading channel, and the channel state is kept unchanged in T time slots;
nth of u user receiving end r Root antenna and transmitting end n t Channel gain of root antenna is
Figure BDA0003349661240000044
Nth of u user receiving end r The channel gain vector of the root antenna and the transmitting end is
Figure BDA0003349661240000045
The channel matrix between the receiving end and the transmitting end of the u-th user is expressed as
Figure BDA0003349661240000046
[·] T Representing a transpose;
the system receiver is shown in FIG. 2, the u-th user is at the n-th user j Received signal of space-time block
Figure BDA0003349661240000047
First to the detection matrix V u Preprocessing to obtain a detected signal;
performing multi-user detection on the detected signals to obtain a transmission matrix
Figure BDA0003349661240000048
Is estimated by
Figure BDA0003349661240000049
For the estimated value
Figure BDA00033496612400000410
Performing demapping to obtain
Figure BDA00033496612400000411
For is to
Figure BDA00033496612400000412
Caching to obtain an estimated value of the coded vector c
Figure BDA00033496612400000413
Will estimate the value
Figure BDA00033496612400000414
Obtaining an estimated value of the original information b through iterative decoding
Figure BDA00033496612400000415
Other steps and parameters are the same as those in the first embodiment.
The third concrete implementation mode: the embodiment is different from the first or second embodiment in that the non-orthogonal space-time codebook based on the CLST is set in the second step based on the first step; the specific process is as follows:
the system adopts a non-orthogonal Space-Time codebook design scheme based on a Cyclic Layered Space Time Architecture (CLST), and better exerts the characteristics of the Space-Time Architecture. Generally, in the research of a downlink non-orthogonal multiple access system, a codebook is not optimized aiming at a space-time structure, so that the adaptability of the codebook to different space-time structures is poor. The method is realized by the following steps:
and (5) carrying out codebook structure design. The space-time codebook shows a mapping relation between a coding vector and a complex space-time codeword matrix on a multidimensional space-time block, and the positions of non-zero elements in the space-time codebook need to be designed. Three structures are provided in the scheme, namely a Non-Overlapping structure (NOS), an Overlapping Structure (OS) and a Trailing Structure (TS).
And designing a symbol set. In the scheme, a codebook design scheme based on Unique Decodable Mapping (UDM) is adopted, and a set element selection scheme from bottom to top is adopted, namely, firstly, symbols are selected according to power of 2 to select a real part and an imaginary part, then, a new set is generated by combination, and finally, a complete symbol set is obtained.
Step two, firstly: designing a codebook structure;
in the CLST codebook, the nonzero element in the l-th row is from cyclic shift of the nonzero element in the l-1-th row, and the row weights of the codebook are the same but the row weights are not necessarily the same;
in the CLST codebook, three codebook structures are provided in the present invention, as shown in fig. 3a, 3b, 3 c:
if non-overlapping NOS structures are used, i.e.
Figure BDA0003349661240000051
Occupies only one resource, ρ =1, and has J = η + (T · N) t )；
Wherein
Figure BDA0003349661240000052
Is n th j Coded vectors corresponding to the space-time blocks; rho is column weight; eta is row weight; t represents the time slot number of the space-time resource block, N t Representing the number of transmit antennas;
if an overlapping OS structure is employed, i.e.
Figure BDA0003349661240000053
Occupies a different number of resources, ρ =1,2 t Is an irregular codebook and has J = η + (T.N) t -1)；
If a trailing TS structure is used, i.e.
Figure BDA0003349661240000054
Each symbol in (1) occupies the same number of resources, and rho is the same; in the simulation, an OS structure is adopted;
step two: designing a symbol set:
a code element design scheme based on Unique Decodable Mapping (UDM) is adopted, and a bottom-up collection element selection scheme is adopted; the process is as follows:
the selection of the symbols is performed in powers of 2,
Figure BDA0003349661240000055
then the real part and the imaginary part are combined to form a new set
Figure BDA0003349661240000056
Finally constituting a symbol set Ω = { Ω = re ,Ω im ,Ω co }；
In the formula, omega re Is the real part, Ω im Is an imaginary part;
Figure BDA0003349661240000057
is a positive integer set; omega re Is omega re Any of (1); omega im Is omega im Any of (1); i is an imaginary unit.
Other steps and parameters are the same as those in the first or second embodiment.
The fourth concrete implementation mode: the difference between this embodiment and one of the first to third embodiments is that, in the third step, joint precoding and signal detection are performed based on the second step; the specific process is as follows:
the system adopts a combined precoding and signal detection scheme, and improves the performance relative to a classical scheme under the condition that a channel matrix is not of a full rank. Under the condition of comprehensively considering complexity and detection effect, the scheme adopts an Amplitude Partial Traversal Search (APTS) precoding algorithm, the core idea of the algorithm is to design an objective function by taking Minimum Sum Mean Square Error (Min-SMSE) as a criterion, and because the objective function has no closed solution, traversal search is needed to solve, and the algorithm ignores phase information to reduce complexity. The method is realized by the following steps:
initializing a sub-constellation in combination with a selection method of a symbol set
Figure BDA0003349661240000061
And calculating to obtain the corresponding minimum amplitude ratio alpha min ；
Traversing the value range of the amplitude ratio alpha and the amplitude beta, generating a pre-coding matrix, simulating the sending process, and processing at a receiving end to obtain a pre-coded signal
Figure BDA0003349661240000062
Is estimated value of
Figure BDA0003349661240000063
Then further processing to obtain the sending symbol
Figure BDA0003349661240000064
Is estimated value of
Figure BDA0003349661240000065
And eliminating the corresponding interference to obtain the detection result
Figure BDA0003349661240000066
And calculating a corresponding SMSE value;
corresponding to a certain value of alpha and beta, the minimum SMSE value can be obtained, and the precoding matrix corresponding to the value is selected for sending signals.
Step three, according to the rule of codebook design, the code element sets of each line are the same, so that the first eta code elements of the first line of the codebook are only needed to be set;
of the utilization type
Figure BDA0003349661240000067
Complete sub-constellation
Figure BDA0003349661240000068
Initializing the numerical value of each constellation point;
wherein, the first and the second end of the pipe are connected with each other,
Figure BDA0003349661240000069
to transmit the matrix, n t ∈N t ，N t Represents the number of transmit antennas, t represents time;
Figure BDA00033496612400000610
is the intermediate variable(s) of the variable,
Figure BDA00033496612400000611
Figure BDA00033496612400000612
is composed of
Figure BDA00033496612400000613
The jth element of (a); omega j,1 (1) Is any element in the code element set omega;
step three and two, using type
Figure BDA00033496612400000614
Calculating to obtain corresponding minimum amplitude ratio alpha min ；
Figure BDA00033496612400000615
Wherein psi i 、ψ j 、ψ k Psi (t) is a sub-constellation diagram,
Figure BDA00033496612400000616
ψ j ,ψ k ∈Ψ(t)，
Figure BDA00033496612400000617
a sub-constellation diagram is included; alpha is the average amplitude ratio distributed to different empty blocks through a precoding matrix;
step three, traversing the average amplitude ratio alpha and the amplitude beta distributed on different space-time blocks, avoiding too large difference of the transmitting power of different antennas,
Figure BDA00033496612400000618
α＝(1+l/L)α min generating a precoding matrix (amplitude ratio α and amplitude β for each traversal) W (t);
step three, traversing the value range of the amplitude ratio alpha and the amplitude ratio beta, generating a pre-coding matrix, simulating the sending process, and processing at a receiving end to obtain a pre-coded signal
Figure BDA0003349661240000071
Is estimated by
Figure BDA0003349661240000072
Then further processing to obtain the sending symbol
Figure BDA0003349661240000073
Is estimated value of
Figure BDA0003349661240000074
And eliminating the corresponding interference to obtain the detection result
Figure BDA0003349661240000075
And calculating a corresponding SMSE value;
processing space-time coding by using the obtained precoding matrix W (t) to obtain a receiving signal corresponding to the transmitting signal, and then the nth user is in the nth user j The received signal expression of each space-time block is:
Figure BDA0003349661240000076
in the formula (I), the compound is shown in the specification,
Figure BDA0003349661240000077
for the u-th user at the n-th j Noise on each space-time block; h u A channel matrix between the u-th user receiving end and the transmitting end is set;
Figure BDA0003349661240000078
is at the n-th j Transmit symbols over a number of space-time blocks;
the u user is at the n j N on each space-time block r The received signal on the root receive antenna is represented as
Figure BDA0003349661240000079
In the formula (I), the compound is shown in the specification,
Figure BDA00033496612400000710
is a function of the intermediate variable(s),
Figure BDA00033496612400000711
Figure BDA00033496612400000712
for the u-th user at the n-th j N on each space-time block r Receiving noise on an antenna;
Figure BDA00033496612400000713
for the nth user receiving end r Root antenna and transmitting end Nth t The channel gain of the root antenna is,
Figure BDA00033496612400000714
is at the n-th j N on each space-time block t Transmitting symbols on the root transmit antenna;
Figure BDA00033496612400000715
is n th t -average amplitude ratio for 1 transmit antenna; epsilon is a power normalization factor;
for received signal
Figure BDA00033496612400000716
Processing to obtain a pre-coded signal
Figure BDA00033496612400000717
Is estimated value of
Figure BDA00033496612400000718
As shown in
Figure BDA00033496612400000719
In the formula (I), the compound is shown in the specification,
Figure BDA00033496612400000720
is composed of
Figure BDA00033496612400000721
The conjugate value of (d);
then according to the order of the amplitude from large to small
Figure BDA00033496612400000722
To obtain a detected symbol
Figure BDA00033496612400000723
As shown in the following formula:
Figure BDA00033496612400000724
in the formula (I), the compound is shown in the specification,
Figure BDA00033496612400000725
in order to detect the symbols, a symbol is detected,
Figure BDA00033496612400000726
is as follows
Figure BDA00033496612400000727
A transmitting antenna, n t Is the n-th t A plurality of transmitting antennas;
Figure BDA00033496612400000728
is the n-th r -average amplitude ratio for 1 receive antenna,
Figure BDA00033496612400000729
is as follows
Figure BDA00033496612400000730
The average amplitude ratio corresponding to the root transmitting antenna;
based on
Figure BDA00033496612400000731
Calculating a minimum Sum Mean Square Error (SMSE) value gamma;
the mean square error SMSE value Γ is expressed as:
Figure BDA0003349661240000081
and step three, selecting precoding matrixes W (t) corresponding to alpha and beta values corresponding to the minimum mean square error SMSE value gamma.
In the simulation process, the APTS algorithm is adopted, and compared with a Diagonal element phase traversal (DE-PTS) algorithm, an All-element phase traversal (Al Elements PTS, AE-PTS) algorithm and an amplitude part traversal and phase traversal search (APT-PTS) algorithm in performance and complexity.
Other steps and parameters are the same as those in one of the first to third embodiments.
The fifth concrete implementation mode: the difference between this embodiment and the first to the fourth embodiments is that the precoding matrix in the third step
Figure BDA0003349661240000082
Wherein
Figure BDA0003349661240000083
Δ β =0,2, …, L-1, Δ β is a magnitude interval set to avoid too large difference in transmission power of different antennas, L =1,2, … L, L represents a magnitude, and α represents an average magnitude ratio assigned to different null blocks by a precoding matrix; the larger L is, the smaller the quantization interval is, and the higher the precision is.
Other steps and parameters are the same as in one of the first to fourth embodiments.
The sixth specific implementation mode: this embodiment is different from one of the first to fifth embodiments in that the nth component j Of the t-th time slot on a space-time block
Figure BDA0003349661240000084
The expression is as follows:
Figure BDA0003349661240000085
in the formula, E is an average value; u is the total number of the users,
Figure BDA0003349661240000086
for the u-th user at the n-th j The detected signal over the number of space-time blocks,
Figure BDA0003349661240000087
is n th j The transmitted signal over the number of space-time blocks,
Figure BDA0003349661240000088
is the square of the F norm; v u (t) is the detection matrix of the t-th time slot.
Other steps and parameters are the same as in one of the first to fifth embodiments.
The seventh embodiment: in this embodiment, the difference between the first embodiment and the sixth embodiment is that the fourth step uses the viterbi decoder to eliminate the signal detected in the third step
Figure BDA0003349661240000089
(detection symbol in step three)
Figure BDA00033496612400000810
) Of the other of the interference (c) in (d),
Figure BDA00033496612400000811
obtaining a final detection signal;
in obtaining
Figure BDA0003349661240000091
Then, based on the principle of minimum Euclidean distance, the sub-constellation diagram on the corresponding space-time resource block is obtained
Figure BDA0003349661240000092
Upper acquisition pair
Figure BDA0003349661240000093
Is estimated and then eliminated by this estimation
Figure BDA0003349661240000094
Interference with subsequent detection.
The system employs Viterbi-based decodingInterference elimination iterative decoding algorithm of device for detecting signals containing more interference
Figure BDA0003349661240000095
Processing is performed to improve performance. The core idea of the algorithm is to introduce external information by adding channel coding, so that iterative decoding algorithm can be applied to eliminate signals obtained by detection
Figure BDA0003349661240000096
Of the other interference. The method is realized by the following steps:
calculating the numerical value of each constellation point of the main constellation diagram to complete codebook mapping;
calculating to obtain N J The probability of the coding bit on each space-time block is transmitted to a Viterbi decoder, and then the original transmission bit is decoded, thereby completing the acquisition of initial information;
step four to one, according to
Figure BDA0003349661240000097
Calculating the numerical value of each constellation point of the main constellation diagram to complete codebook mapping;
step four, traversing the time slot number T and the transmitting antenna number N of the space-time resource block t Calculating the detection signal
Figure BDA0003349661240000098
Step four and step three, utilizing MAP criterion pair
Figure BDA0003349661240000099
Estimate to obtain
Figure BDA00033496612400000910
Step four, calculating N J Probability of coded bits over a space-time block;
the calculated bit probability is transmitted to a Viterbi decoder, and the receiver decodes the original transmission bit of the transmitter
Figure BDA00033496612400000911
(of a receiver);
and step three, repeatedly executing the step one to the step four until the iteration times reach a set value or the calculated SMSE value is smaller than the set value.
Performing iterative decoding, i.e. decoding the original transmission bits
Figure BDA00033496612400000912
Is subjected to recoding and mapping to obtain
Figure BDA00033496612400000913
And
Figure BDA00033496612400000914
and reprocessed to update the detected signal
Figure BDA00033496612400000915
And then repeating the fourth step and the second step, and carrying out iterative decoding until the iteration times reach a set value or the SMSE value obtained by calculation is smaller than the set value.
Other steps and parameters are the same as those in one of the first to sixth embodiments.
The specific implementation mode is eight: the difference between this embodiment and the first to seventh embodiments is that, in the second step, the number of time slots T and the number of transmitting antennas N of the space-time resource block are traversed t Calculating the detection signal
Figure BDA00033496612400000916
The expression is as follows:
Figure BDA0003349661240000101
in the formula (I), the compound is shown in the specification,
Figure BDA0003349661240000102
for the u-th user at the n-th j On a space-time block
Figure BDA0003349661240000103
From the transmitted signal estimates on the receive antennas,
Figure BDA0003349661240000104
for the u-th user at the n-th j On a space-time block
Figure BDA0003349661240000105
Transmitting a detection signal on an antenna;
Figure BDA0003349661240000106
for the u-th user at the n-th j N on each space-time block t And transmitting the detection signal obtained by the ith iteration on the antenna.
Other steps and parameters are the same as those in one of the first to seventh embodiments.
The specific implementation method nine: the difference between this embodiment and the first to eighth embodiments is that the MAP criterion pair is used in the third and fourth steps
Figure BDA0003349661240000107
Estimate to obtain
Figure BDA0003349661240000108
The expression is as follows:
Figure BDA0003349661240000109
in the formula, phi k The numerical value of each constellation point of the main constellation diagram;
Figure BDA00033496612400001010
for the nth user j The detected signal on each space-time block is expressed as
Figure BDA00033496612400001011
Wherein
Figure BDA00033496612400001012
For the u-th user at the n-th j The detected signal over each of the space-time blocks,
Figure BDA00033496612400001013
Figure BDA00033496612400001014
for the nth user j A received signal over a space-time block.
Other steps and parameters are the same as those in one to eight of the embodiments.
The detailed implementation mode is ten: the difference between this embodiment and one of the first to ninth embodiments is that N is calculated in the fourth step J Probability of coded bits over a space-time block; the expression is as follows:
Figure BDA00033496612400001015
Figure BDA00033496612400001016
in the formula (I), the compound is shown in the specification,
Figure BDA00033496612400001017
is the nth iteration of 0 j The coded vector corresponding to the jth element of each space-time block,
Figure BDA00033496612400001018
is the nth iteration of 0 j The coded vector corresponding to the jth element of each space-time block,
Figure BDA00033496612400001019
is the nth user of the 0 th iteration j Post-detection signal on individual space-time blocks, N 0 Is the single-sided power spectral density of gaussian white noise.
Other steps and parameters are the same as those in one of the first to ninth embodiments.
The following examples were used to demonstrate the beneficial effects of the present invention:
the first embodiment is as follows:
the conditions were set as follows:
1) The channel is a Rayleigh flat fading channel;
2) The codebook structure is CLST-OS, and the code word construction mode is UDM;
3) The channel coding adopts (3,1,2) convolutional code;
4) The iteration algorithm backtracks the length 96, and the maximum number of iterations is 5;
the downlink multi-user MIMO transmission scheme combining the non-orthogonal codebook and precoding described in this embodiment is performed according to the following steps:
the method comprises the following steps: generating an original bit stream by a user, carrying out space-time codebook mapping after multi-user channel coding, and multiplying a space-time codebook of each user by a pre-coding matrix to obtain a sending matrix;
step two: the signal transmitted by the user reaches the receiver through a Rayleigh flat fading channel;
step three: the receiver end processes the received signal, firstly multiplies the received signal by the detection matrix, and then carries out the processes of multi-user detection, demapping, viterbi decoding, iterative decoding and the like, thereby obtaining the final detection result.
The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore intended that all such changes and modifications be considered as within the spirit and scope of the appended claims.

Claims (5)

1. The multi-user MIMO transmission method based on the joint non-orthogonal codebook and pre-coding design is characterized in that: the method comprises the following specific processes:
step one, establishing a downlink MU-MIMO system of a joint non-orthogonal space-time codebook;
the MIMO is multiple input multiple output; MU is multiuser;
step two, setting a non-orthogonal space-time codebook based on CLST based on the step one;
the CLST is a cyclic layered space-time structure;
step three, performing combined precoding and signal detection based on the step two;
step four, eliminating the signal obtained by the detection in the step three by adopting a Viterbi decoder
Figure FDA0003788653290000011
To obtain a final detection signal;
establishing a downlink MU-MIMO system of a joint non-orthogonal space-time codebook in the first step; the specific process is as follows:
the method comprises the following steps: the joint non-orthogonal space-time codebook has U users in the downlink MU-MIMO system, wherein the original information b of the user U u Are binary bit streams of length K; u is more than or equal to 1 and less than or equal to U;
original information b of user u Carrying out multi-user channel coding to obtain a coded vector c with the length of N;
dividing the encoded vector c into N J Each block comprising J bits, and then mapping each block to a length of T.N by a space-time codebook F t Space-time codeword vector of
Figure FDA0003788653290000012
Wherein T represents the number of time slots of the space-time resource block, N t Representing the number of transmit antennas;
passing the space-time code word vector through a precoding sequence W = [ W (1), …, W (T), …, W (T)]Obtaining a transmit matrix
Figure FDA0003788653290000013
Wherein
Figure FDA0003788653290000014
The first step is: the sending matrixes of the users obtained in the step one by one are used
Figure FDA0003788653290000015
Get throughThe flat fading channel is used for reaching a receiver, and the channel state is kept unchanged in T time slots;
nth of u user receiving end r Root antenna and transmitting end nth t Channel gain of root antenna is
Figure FDA0003788653290000016
Nth of u user receiving end r The channel gain vector of the root antenna and the transmitting end is
Figure FDA0003788653290000017
The channel matrix between the receiving end and the transmitting end of the u-th user is expressed as
Figure FDA0003788653290000018
[·] T Representing a transpose;
setting a non-orthogonal space-time codebook based on CLST in the step two based on the step one; the specific process is as follows:
step two, firstly: designing a codebook structure;
in the CLST codebook, the nonzero elements in the l line are from the cyclic shift of the nonzero elements in the l-1 line, and the line weights of the codebook are the same;
in the CLST codebook, three codebook structures are provided:
if non-overlapping NOS structures are used, i.e.
Figure FDA0003788653290000021
Occupies only one resource, ρ =1, and has J = η + (T · N) t )；
Wherein
Figure FDA0003788653290000022
Is n th j A coded vector corresponding to each space-time block; rho is column weight; eta is row weight; t represents the time slot number of the space-time resource block;
if an overlapping OS structure is employed, i.e.
Figure FDA0003788653290000023
Occupies a different number of resources, ρ =1,2 t Is an irregular codebook and has J = η + (T.N) t -1)；
If a trailing TS structure is used, i.e.
Figure FDA0003788653290000024
Each symbol in (2) occupies the same number of resources, and rho is the same;
step two: designing a symbol set:
the selection of the symbols is done in powers of 2,
Figure FDA0003788653290000025
then the real part and the imaginary part are combined to form a new set
Figure FDA0003788653290000026
Finally constituting a symbol set Ω = { Ω = re ,Ω im ,Ω co }；
In the formula, omega re Is the real part, Ω im Is an imaginary part;
Figure FDA0003788653290000027
is a positive integer set; omega re Is omega re Any of (1); omega im Is omega im Any of (1); i is an imaginary unit;
performing joint precoding and signal detection based on the step two in the step three; the specific process is as follows:
step three one, utilizing type
Figure FDA0003788653290000028
Complete sub-constellation
Figure FDA0003788653290000029
Initializing the numerical value of each constellation point;
wherein, the first and the second end of the pipe are connected with each other,
Figure FDA00037886532900000210
is at the n-th j N on each space-time block t Transmitting symbols, n, on root transmitting antennas t ∈N t T represents time;
Figure FDA00037886532900000211
is the intermediate variable(s) of the variable,
Figure FDA00037886532900000212
Figure FDA00037886532900000213
is composed of
Figure FDA00037886532900000214
The jth element of (a); omega j,1 (1) Is any element in the code element set omega;
step three and two, using type
Figure FDA00037886532900000215
Calculating to obtain corresponding minimum amplitude ratio alpha min ；
Figure FDA00037886532900000216
Wherein psi i 、ψ j 、ψ k Psi (t) is a sub-constellation diagram,
Figure FDA00037886532900000217
a sub-constellation diagram is included; alpha is the average amplitude ratio;
step three, traversing the average amplitude ratio alpha and the amplitude beta distributed on different space-time blocks,
Figure FDA0003788653290000031
α＝(1+l/L)α min generating a precoding matrix W (t):
Figure FDA0003788653290000032
wherein
Figure FDA0003788653290000033
Δ β =0,2, …, L-1, Δ β is the amplitude interval, L =1,2, … L, L denotes the amplitude, α denotes the average amplitude ratio; epsilon is a power normalization factor;
step three, processing space-time coding by using the obtained precoding matrix W (t) to obtain a receiving signal corresponding to the sending signal, so that the nth user is in the nth user j The received signal expression of each space-time block is:
Figure FDA0003788653290000034
in the formula (I), the compound is shown in the specification,
Figure FDA0003788653290000035
for the u-th user at the n-th j Noise on space-time blocks; h u A channel matrix between the u-th user receiving end and the transmitting end;
Figure FDA0003788653290000036
is at the n-th j A transmit symbol over a space-time block;
the u user is at the n j N on each space-time block r The received signal on the root receive antenna is represented as
Figure FDA0003788653290000037
In the formula (I), the compound is shown in the specification,
Figure FDA0003788653290000038
is the intermediate variable(s) of the variable,
Figure FDA0003788653290000039
Figure FDA00037886532900000310
for the u-th user at the n-th j N on each space-time block r Receiving noise on an antenna;
Figure FDA00037886532900000311
for the nth user receiving end r Root antenna and transmitting end Nth t The channel gain of the root antenna is,
Figure FDA00037886532900000312
is n th t -average amplitude ratio for 1 transmit antenna;
for received signal
Figure FDA00037886532900000313
Processing to obtain a pre-coded signal
Figure FDA00037886532900000314
Is estimated value of
Figure FDA00037886532900000315
As shown in
Figure FDA00037886532900000316
In the formula (I), the compound is shown in the specification,
Figure FDA00037886532900000317
is composed of
Figure FDA00037886532900000318
The conjugate value of (a);
then according to the order of the amplitude from large to small
Figure FDA00037886532900000319
To obtain a detected symbol
Figure FDA00037886532900000320
As shown in the following formula:
Figure FDA00037886532900000321
in the formula (I), the compound is shown in the specification,
Figure FDA00037886532900000322
in order to detect the symbols, the receiver is,
Figure FDA00037886532900000323
is as follows
Figure FDA00037886532900000324
A transmitting antenna, n t Is the n-th t A plurality of transmitting antennas;
Figure FDA00037886532900000325
is n th r -average amplitude ratio for 1 receive antenna,
Figure FDA0003788653290000041
is as follows
Figure FDA0003788653290000042
The average amplitude ratio corresponding to the root transmitting antenna;
based on
Figure FDA0003788653290000043
Calculating a minimum Sum Mean Square Error (SMSE) value gamma;
the mean square error SMSE value Γ is expressed as:
Figure FDA0003788653290000044
in the formula (I), the compound is shown in the specification,
Figure FDA0003788653290000045
is n th j Min-SMSE of the t-th time slot on each space-time block; n is a radical of J The total number of the empty time blocks;
step three, selecting precoding matrixes W (t) corresponding to alpha and beta values corresponding to minimum and mean square error SMSE values gamma;
in the fourth step, the signal obtained by the detection of the third step is eliminated by adopting a Viterbi decoder
Figure FDA0003788653290000046
The interference in (2) is detected by the interference sensor,
Figure FDA0003788653290000047
obtaining a final detection signal;
step four to one, according to
Figure FDA0003788653290000048
Calculating the numerical value of each constellation point of the main constellation diagram to complete codebook mapping;
step four, traversing the time slot number T and the transmitting antenna number N of the space-time resource block t Calculating the detection signal
Figure FDA0003788653290000049
Step four and step three, utilizing MAP criterion pair
Figure FDA00037886532900000410
Estimate to obtain
Figure FDA00037886532900000411
Step four, calculating N J Probability of coded bits over a space-time block;
the calculated bit probability is transmitted to a Viterbi decoder, and the original transmission bit of the transmitter is decoded by a receiver
Figure FDA00037886532900000412
And step IV, repeatedly executing the step I to the step IV until the iteration times reach a set value or the calculated SMSE value is smaller than the set value.
2. The multi-user MIMO transmission method based on joint non-orthogonal codebook and precoding design as claimed in claim 1, wherein: n in the third step j Of the t-th time slot on a space-time block
Figure FDA00037886532900000413
The expression is as follows:
Figure FDA00037886532900000414
in the formula, E is an average value; u is the total number of the users,
Figure FDA00037886532900000415
for the u-th user at the n-th j The detected signal over the number of space-time blocks,
Figure FDA00037886532900000416
is the n-th j The transmitted symbols over the number of space-time blocks,
Figure FDA00037886532900000417
is the square of the F norm; v u (t) is the detection matrix of the t-th time slot.
3. The multi-user MIMO transmission method based on joint non-orthogonal codebook and precoding design according to claim 2, characterized in that: in the fourth step, the time slot number T and the transmitting antenna number N of the ergodic space-time resource block t Calculating the detection signal
Figure FDA0003788653290000051
The expression is as follows:
Figure FDA0003788653290000052
in the formula (I), the compound is shown in the specification,
Figure FDA0003788653290000053
for the u-th user at the n-th j On a space-time block
Figure FDA0003788653290000054
From the transmitted signal estimates on the receive antennas,
Figure FDA0003788653290000055
for the u-th user at the n-th j On a space-time block
Figure FDA0003788653290000056
Transmitting a detection signal on an antenna;
Figure FDA0003788653290000057
for the u-th user at the n-th j N on each space-time block t And transmitting the detection signal obtained by the ith iteration on the antenna.
4. The multi-user MIMO transmission method based on joint non-orthogonal codebook and precoding design as claimed in claim 3, wherein: using MAP criterion pair in the third step
Figure FDA0003788653290000058
Estimate to obtain
Figure FDA0003788653290000059
The expression is as follows:
Figure FDA00037886532900000510
in the formula, phi k The numerical value of each constellation point of the main constellation diagram;
Figure FDA00037886532900000511
for the nth user j The detected signal on each space-time block is expressed as
Figure FDA00037886532900000512
Wherein
Figure FDA00037886532900000513
For the u-th user at the n-th j The detected signal over each of the space-time blocks,
Figure FDA00037886532900000514
Figure FDA00037886532900000515
for the nth user j A received signal over a space-time block.
5. The multi-user MIMO transmission method based on the joint non-orthogonal codebook and precoding design as claimed in claim 4, wherein: calculating N in the fourth step J Probability of coded bits over a space-time block; the expression is as follows:
Figure FDA00037886532900000516
Figure FDA00037886532900000517
in the formula (I), the compound is shown in the specification,
Figure FDA00037886532900000518
at iteration 0N th order j The coded vector corresponding to the jth element of each space-time block,
Figure FDA00037886532900000519
is the nth iteration of 0 j The coded vector corresponding to the jth element of each space-time block,
Figure FDA00037886532900000520
is the nth user of the 0 th iteration j Post-detection signal on individual space-time blocks, N 0 Is the single-sided power spectral density of gaussian white noise.
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