CN109743270B - Channel estimation method based on 5G multi-user multiplexing - Google Patents

Channel estimation method based on 5G multi-user multiplexing Download PDF

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CN109743270B
CN109743270B CN201910226060.8A CN201910226060A CN109743270B CN 109743270 B CN109743270 B CN 109743270B CN 201910226060 A CN201910226060 A CN 201910226060A CN 109743270 B CN109743270 B CN 109743270B
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user
channel
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CN109743270A (en
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王丹
丁钰泰
陈发堂
李小文
王华华
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Chongqing University of Post and Telecommunications
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Abstract

The invention belongs to the technical field of mobile communication, and relates to a method for distinguishing demodulation reference signals superposed by all users at a receiving end and estimating channel impulse response of each user under the condition that multiple users simultaneously transmit signals at the same frequency, in particular to a channel estimation method based on 5G multi-user multiplexing. The method comprises the steps of utilizing the characteristic that each user generates the DMRS in a PUCCH transmission format 4 of the 5G system, constructing a special signal matrix, then utilizing the signal matrix to combine with the traditional LMMSE channel estimation and DCT interpolation algorithm, solving the problem of superposition of reference signals in multi-user multiplexing, and displaying through analysis and simulation results.

Description

Channel estimation method based on 5G multi-user multiplexing
Technical Field
The invention belongs to the technical field of mobile communication, and relates to a method for separating DeModulation Reference signals (DMRS) after all users are superposed at a receiving end under the condition that multiple users simultaneously transmit signals at the same frequency and estimating channel impulse response of each user, in particular to a channel estimation method based on 5G multi-user multiplexing.
Background
A Physical Uplink Control CHannel (PUCCH) of the 5G system is mainly used to send Uplink Control Information (UCI), which includes a scheduling request, CHannel state Information, response Information of a hybrid automatic repeat request, and the like, and these pieces of Information have a decisive role in whether an Uplink shared CHannel and a downlink shared CHannel can work normally, so that it is obvious that correctly solving UCI Information of each user is important for the 5G system, a CHannel estimation algorithm is a key step for solving UCI Information, and accuracy of CHannel estimation directly affects whether a base station can correctly solve UCI Information of a user.
The PUCCH in the 5G system supports 5 transmission formats, in order to improve channel capacity and spectrum utilization efficiency, transmission format 0, format 1, and format 4 in the PUCCH can support multiple users to simultaneously transmit signals at the same frequency, and in the case that multiple users simultaneously transmit signals at the same frequency, demodulation reference signals of these users are superimposed together and interfere with each other in the channel transmission process, which causes great difficulty in channel estimation at the receiving end, and at this time, the difficulty in channel estimation is that DMRSs for the users are superimposed together are distinguished and DMRS position channel impulse response of each user is estimated, however, the traditional classical single-user channel estimation algorithm has great limitations, such as Least Square (LS) algorithm and Linear Minimum Mean Square Error (LMMSE) algorithm can only be applied to channel estimation of a single-user single antenna, the DMRS superposition problem in multi-user multiplexing cannot be solved.
Disclosure of Invention
The present invention is directed to solving the problems of the prior art described above. The channel estimation method is suitable for a PUCCH transmission format 4 of a 5G system, and solves the problems of DMRS superposition and mutual interference of each user under the condition of multi-user multiplexing. The method constructs a special signal matrix by utilizing the characteristic that each user generates the DMRS in the PUCCH transmission format 4 of the 5G system, then utilizes the signal matrix to combine the traditional LMMSE channel estimation and DCT interpolation algorithm, solves the problem of superposition of reference signals in multi-user multiplexing, is suitable for a receiving end under the multi-user multiplexing condition of the PUCCH of the 5G system through analysis and simulation result display, has moderate complexity, is favorable for development of an embedded platform, and can be applied to practical projects. The technical scheme of the invention is as follows:
a channel estimation method based on multi-user multiplexing of 5G is suitable for an uplink control channel transmission format 4 of a 5G system; the method comprises the following steps:
step 1, sending uplink control information by adopting a sending format 4, and decomposing frequency domain cyclic shift in a demodulation reference signal into symbol frequency domain cyclic shift and user frequency domain cyclic shift after the uplink control information reaches a base station end through channel transmission; thereby making the signal matrix of the receiving end
Figure BDA0002005231200000021
Is constructed in such a way that
Figure BDA0002005231200000022
Dimension special matrix
Figure BDA0002005231200000023
Step 2, adopting a method based on linear minimum mean square error to carry out alignment on the special matrix
Figure BDA0002005231200000024
Is processed to obtain
Figure BDA0002005231200000025
Dimension matrix
Figure BDA0002005231200000026
Step 3, to the obtained
Figure BDA0002005231200000027
Each row in the matrix
Figure BDA0002005231200000028
Discrete cosine transform of points to obtain
Figure BDA0002005231200000029
Dimension matrix
Figure BDA00020052312000000210
Step 4, matrix after discrete cosine transform
Figure BDA00020052312000000211
Each row in the sequence is subjected to the inverse extensible discrete cosine transform to obtain
Figure BDA00020052312000000212
Dimension matrix
Figure BDA00020052312000000213
Step 5, obtaining an inverse transformation matrix
Figure BDA00020052312000000214
Of each row, obtaining the effective value of
Figure BDA00020052312000000215
Of (2) matrix
Figure BDA00020052312000000216
According to a matrix
Figure BDA00020052312000000217
Estimating a channel impulse response matrix of symbols occupied by a plurality of user demodulation reference signals; carrying out time domain linear interpolation on the data signals to obtain signal impulse response of each data signal position;
wherein N isTIndicating the number of multiplexed users of transmission format 4;
Figure BDA00020052312000000218
indicating the number of sub-carriers on one physical resource block.
Specifically, there is N in the 5G systemTThe method comprises the steps that signals are sent by the users at the same time, wherein demodulation reference signals of all the users occupy the ith symbol in a time domain, a physical resource block is occupied in a frequency domain, the demodulation reference signals on the ith symbol of a receiving end are processed after the signals pass through a channel, and the demodulation reference signals of all the users are distinguished according to the orthogonality of the demodulation reference signals among the usersAnd finally, estimating the channel impulse response of the data signal by using a linear interpolation algorithm through the channel impulse response of the demodulation reference signal, thereby solving the data information sent by each user.
Further, the signal matrix of the receiving end
Figure BDA0002005231200000031
Comprises the signal r received by removing the respective subcarriers on the respective symbolsl(i) Symbol frequency domain cyclic shift a inlTo thereby determine
Figure BDA0002005231200000032
Specifically, the calculation is performed by the following formula:
Figure BDA0002005231200000033
Figure BDA0002005231200000034
wherein the content of the first and second substances,
Figure BDA0002005231200000035
expressed as the received computation signal on the ith subcarrier on the ith symbol;
Figure BDA0002005231200000036
αlrepresenting the cyclic shift of the l-th symbol, alphatRepresenting the frequency domain cyclic shift of the t-th user;
Figure BDA0002005231200000037
represents a ZC sequence; h isl,t(i) Denotes the channel impulse response, z, of the t-th user at the i-th sub-carrier on the l-th symboll,t(i) Representing additive white gaussian noise; denotes conjugation; r isl(i) Is represented on the l-th symbolReceived signals on the i subcarriers.
Further, the frequency domain cyclic shift of the ith symbol is expressed as:
Figure BDA0002005231200000038
the frequency domain cyclic shift of the tth user is expressed as:
Figure BDA0002005231200000039
wherein the content of the first and second substances,
Figure BDA00020052312000000310
nsindicates the time slot number of the current uplink control channel in the data frame,
Figure BDA00020052312000000311
indicating the number of symbols contained in each slot, lrIndicates the position of the current symbol relative to the first symbol for transmitting the uplink control channel, l indicates the position of the current symbol in the whole time slot, and c indicates the length of
Figure BDA00020052312000000312
A pseudo-random sequence of (a); m is0＝0，mcsRepresenting values assigned by the base station to different users.
Further, special matrices
Figure BDA00020052312000000313
Is constructed in a manner that includes
Figure BDA00020052312000000314
Wherein the content of the first and second substances,
Figure BDA00020052312000000315
representation matrix
Figure BDA00020052312000000316
Is represented by the sequence of the nth row of
Figure BDA00020052312000000317
Further, the step 2 comprises
Figure BDA0002005231200000041
Wherein the content of the first and second substances,
Figure BDA0002005231200000042
Figure BDA0002005231200000043
to represent
Figure BDA0002005231200000044
Of the autocorrelation matrix RSNRepresents the signal-to-noise ratio of the channel, I represents an identity matrix, β { | x {, E { | x {, q {,/h {k|2}·E{|1/xk|2}，xkRepresenting the actual complex-valued signal; e {. cndot.) represents expectation.
Further, the step 3 comprises
Figure BDA0002005231200000045
Wherein D is
Figure BDA0002005231200000046
A discrete cosine transform matrix of points, in which matrix D each element (m, n) comprises
Figure BDA0002005231200000047
Wherein the content of the first and second substances,
Figure BDA0002005231200000048
Anrepresenting the magnitude in a discrete cosine transform, when n is 0,
Figure BDA0002005231200000049
when n ≠ 0, it is determined,
Figure BDA00020052312000000410
further, the step 4 comprises
Figure BDA00020052312000000411
Formula (I) wherein
Figure BDA00020052312000000412
Is composed of
Figure BDA00020052312000000413
The dimension matrix is a matrix of dimensions,
Figure BDA00020052312000000414
is composed of
Figure BDA00020052312000000415
The dimension matrix is a matrix of dimensions,
Figure BDA00020052312000000416
the matrix elements (m, n) in (1) include
Figure BDA00020052312000000417
Wherein the content of the first and second substances,
Figure BDA00020052312000000418
M′＝M/NT，m＝0,1,…,M/NT，l＝-(NT-1), …,0, …, M-1, when M is 0,
Figure BDA00020052312000000419
when m is not equal to 0, the ratio of m,
Figure BDA00020052312000000420
further, the estimating of the channel impulse response matrix of the symbols occupied by the multiple user demodulation reference signals in step 5 includes pairing
Figure BDA00020052312000000421
The matrix takes the effective value of each row and represents it as
Figure BDA00020052312000000422
Wherein the content of the first and second substances,
Figure BDA00020052312000000423
i denotes an identity matrix and 0 denotes a zero matrix, then the estimation value of the channel impulse response matrix at the demodulation reference signal for each user is found as:
Figure BDA00020052312000000424
Figure BDA00020052312000000425
representation matrix
Figure BDA00020052312000000426
The conjugate transpose of (a) is performed,
Figure BDA00020052312000000427
is composed of
Figure BDA00020052312000000428
A dimension matrix.
Further, the step 5 of obtaining the signal impulse response of each data signal position includes using a time-domain linear interpolation algorithm to obtain the channel impulse response at the kth subcarrier of the ith symbol in the data signal, namely (k, l), which is expressed as:
Figure BDA00020052312000000429
wherein Hp(k,l1) And Hp(k,l2) Respectively representing the estimated two adjacent symbols occupied by the demodulation reference signal1And l2The channel impulse response of the k-th subcarrier above.
The invention has the following advantages and beneficial effects:
aiming at the problems of DMRS superposition and mutual interference in multi-user multiplexing, the invention designs a special signal matrix according to the DMRS characteristics of users, and then the superposed DMRS can be effectively separated by utilizing the signal matrix and combining the traditional channel estimation method, and the channel impulse response of each user is estimated. The invention has outstanding performance, takes four users as scenes, and reduces the error rate to 0 when the signal-to-noise ratio is more than minus 18dB under a Gaussian channel. In the EPA channel, the error rate drops to 0 when the signal-to-noise ratio is above 8 dB. The invention can be widely applied to the project development of the PUCCH of the 5G system.
Drawings
FIG. 1 is a block diagram of a system in which the present invention is employed;
FIG. 2 is a flow chart of an implementation of the invention providing a diagram of a preferred embodiment;
FIG. 3 is a graph of performance simulation of 2 users and 4 users in a Gaussian channel in accordance with the present invention;
fig. 4 is a graph of performance simulations of 2 users and 4 users in an EPA channel in accordance with the present invention.
Detailed Description
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.
Suppose that in the uplink control channel of the 5G system, as shown in FIG. 1, the number of users in the system is NTThe resource mapping comprises that a signal sent by each user occupies 14 symbols in a time domain, occupies one physical resource block in a frequency domain, and all users occupy the same time-frequency resource when the signal is sent, wherein a demodulation reference signal occupies the ith symbol in the time domain; after the baseband signal is generated, the channel transmission is carried out to generate the corresponding channel impulse response, after the baseband signal reaches the base station end, the base station end starts to solve the baseband signal, the resource mapping is solved, the demodulation reference signal is extracted, the demodulation reference signal of each user is solved according to the method provided by the invention, and the channel is estimated, thereby estimating the channel impulse response of each user.
The present invention sets the fading channel coefficient of each subcarrier to be flat in the frequency domain. As shown in fig. 2, the steps of the present embodiment are as follows:
step 1: according to the characteristics of DMRS generation formula, andthe cyclic shift alpha in the frequency domain in the slot in which the PUCCH is transmitted is decomposed into two parts alpha that vary according to the symbol and according to the user, respectivelylAnd alphatAnd α ═ αl+αtIn which α islRepresenting the cyclic shift of the l-th symbol, alphatRepresenting the frequency domain cyclic shift of the t-th user.
Specifically, the generation formula of the DMRS on the ith symbol is represented as:
Figure BDA0002005231200000061
wherein the content of the first and second substances,
Figure BDA0002005231200000062
it indicates a ZC sequence,
Figure BDA0002005231200000063
indicating the number of sub-carriers on one physical resource block.
The cyclic shift α in the frequency domain in the slot where the PUCCH is transmitted is represented as:
Figure BDA0002005231200000064
further, αlAnd alphanRespectively expressed as:
Figure BDA0002005231200000065
Figure BDA0002005231200000066
wherein the content of the first and second substances,
Figure BDA0002005231200000067
the values of (d) are expressed as:
Figure BDA0002005231200000068
nsindicates the slot number of the current PUCCH in the data frame,
Figure BDA0002005231200000069
indicating the number of symbols contained in each slot, lrDenotes a position of a current symbol with respect to a first symbol of a transmission PUCCH, l denotes a position of the current symbol in the entire slot, and c denotes a length of
Figure BDA00020052312000000610
The pseudo-random sequence of (a). Wherein m is0＝0，mcsWhich represents the values assigned by the base station to different users, and the possible values are 0, 3, 6, and 9.
Step 2: if the DMRS is mapped to the ith symbol in the time domain, the signal r on the ith subcarrier on the ith symbol received by the receiving end is enabled to bel(i) Multiplication by
Figure BDA00020052312000000611
Is calculated to obtain
Figure BDA00020052312000000612
Dimension matrix
Figure BDA00020052312000000613
The calculation signal of the receiving end of the whole physical resource block is expressed as
Figure BDA0002005231200000071
Wherein, the receiving end signal of the whole physical resource block is represented as:
Figure BDA0002005231200000072
specifically, the method comprises the following steps:
Figure BDA0002005231200000073
wherein r isl(i) Represents a received signal on an ith subcarrier on an ith symbol;
Figure BDA0002005231200000074
indicating the ith value in a ZC sequence, wherein the ZC sequence is defined with reference to 3GPP protocol, hl,t(i) Denotes the channel impulse response of the t-th user on the i-th sub-carrier on the l-th symbol, zl,t(i) Representing additive white Gaussian noise, subject to complex Gaussian independence and step-by-step, NTIndicating the number of users in the system.
Multiplying the left and right ends of the equal sign in the formula (5) by
Figure BDA0002005231200000075
Is represented as:
Figure BDA0002005231200000076
and step 3: assume that the number of multiplexed users of PUCCH transmission format 4 is NTConstructing an N according to the characteristics of DMRS of different usersT×NTDimensional signal matrix
Figure BDA0002005231200000077
And combining the matrix obtained in step 1
Figure BDA0002005231200000078
By constructed signal matrix
Figure BDA0002005231200000079
And (4) showing.
Matrix array
Figure BDA00020052312000000710
The concrete expression is as follows:
Figure BDA00020052312000000711
and using formula (5) in step 2
Figure BDA00020052312000000712
Expressed as:
Figure BDA0002005231200000081
wherein the content of the first and second substances,
Figure BDA0002005231200000082
to represent
Figure BDA0002005231200000083
Ith row of the matrix, Hl(:,i)Represents HlIth column of the matrix, HlA channel impulse response matrix representing the ith symbol, the expression is:
Figure BDA0002005231200000084
and 4, step 4: utilizing the signal matrix of the receiving end obtained in the step 2
Figure BDA0002005231200000085
Reconfiguring special matrices
Figure BDA0002005231200000086
Figure BDA0002005231200000087
Is composed of
Figure BDA0002005231200000088
The dimension matrix is a matrix of dimensions,
Figure BDA0002005231200000089
representing the number of sub-carriers on a physical resource block and then pairing according to the LMMSE algorithm
Figure BDA00020052312000000810
Is processed to obtain
Figure BDA00020052312000000811
Dimension matrix
Figure BDA00020052312000000812
Wherein the content of the first and second substances,
Figure BDA00020052312000000813
can be expressed as:
Figure BDA00020052312000000814
wherein the content of the first and second substances,
Figure BDA00020052312000000815
representation matrix
Figure BDA00020052312000000816
Is represented by the sequence of line n of (1):
Figure BDA00020052312000000817
then will be
Figure BDA00020052312000000818
The matrix is processed with an LMMSE channel estimation algorithm:
Figure BDA00020052312000000819
wherein the content of the first and second substances,
Figure BDA00020052312000000820
Figure BDA00020052312000000821
to represent
Figure BDA00020052312000000822
Of the autocorrelation matrix RSNRepresents the signal-to-noise ratio of the channel, I represents an identity matrix, β { | x {, E { | x {, q {,/h {k|2}·E{|1/xk|2}，xkThe actual complex-valued signal is shown, and the β value is related to the modulation scheme, and β is 1 in QPSK modulation, for example.
And 5: to the obtained
Figure BDA0002005231200000091
Each row in the matrix
Figure BDA0002005231200000092
DCT transformation of points to obtain
Figure BDA0002005231200000093
Dimension matrix
Figure BDA0002005231200000094
Available formulas
Figure BDA0002005231200000095
Wherein D is
Figure BDA0002005231200000096
DCT transform matrix of points, the elements (m, n) of the matrix should satisfy the condition:
Figure BDA0002005231200000097
wherein the content of the first and second substances,
Figure BDA0002005231200000098
Anindicating the magnitude used in the DCT transform, when n is 0,
Figure BDA0002005231200000099
when n ≠ 0, it is determined,
Figure BDA00020052312000000910
step 6: for DCT transformed matrix
Figure BDA00020052312000000911
Each row in the sequence is subjected to inverse extensible discrete cosine transform (EIDCT) to obtain
Figure BDA00020052312000000912
Dimension matrix
Figure BDA00020052312000000913
Can be used
Figure BDA00020052312000000914
The formula is expressed in that, among them,
Figure BDA00020052312000000915
is composed of
Figure BDA00020052312000000916
The dimension matrix is a matrix of dimensions,
Figure BDA00020052312000000917
is composed of
Figure BDA00020052312000000918
Dimension matrix, where the matrix elements (m, n) should satisfy the condition:
Figure BDA00020052312000000919
wherein the content of the first and second substances,
Figure BDA00020052312000000920
M′＝M/NT，m＝0,1,…,M/NT，l＝-(NT-1), …,0, …, M-1, when M is 0,
Figure BDA00020052312000000921
when m is not equal to 0, the ratio of m,
Figure BDA00020052312000000922
and 7: to pair
Figure BDA00020052312000000923
The matrix takes the valid value of each row, i.e. for
Figure BDA00020052312000000924
I rows of the matrix, taking its 1+ NT-i columns to
Figure BDA00020052312000000925
Column data, get complete
Figure BDA00020052312000000926
The effective values of the matrix are then formed into an effective data dimension of
Figure BDA00020052312000000927
Of (2) matrix
Figure BDA00020052312000000928
According to
Figure BDA00020052312000000929
The matrix can estimate the channel impulse response of symbols l occupied by a plurality of user DMRSs
Figure BDA00020052312000000930
Dimension matrix
Figure BDA00020052312000000931
To pair
Figure BDA00020052312000000932
The matrix takes the valid value of each row, expressed as:
Figure BDA00020052312000000933
wherein the content of the first and second substances,
Figure BDA00020052312000000934
i denotes an identity matrix and 0 denotes a zero matrix, the DMRS of each user is obtainedThe estimated value of the channel impulse response matrix is:
Figure BDA0002005231200000101
wherein
Figure BDA0002005231200000102
Representation matrix
Figure BDA0002005231200000103
The conjugate transpose of (a) is performed,
Figure BDA0002005231200000104
is composed of
Figure BDA0002005231200000105
A dimension matrix.
And 8: and 7, performing time domain linear interpolation on the data signal according to the channel impulse response of the DMRS obtained in the step 7, and obtaining the channel impulse response of the data signal position.
The channel impulse response at the kth subcarrier of the ith symbol of the data signal, i.e., (k, l), is found by using a time-domain linear interpolation algorithm, and is expressed as:
Figure BDA0002005231200000106
wherein Hp(k,l1) And Hp(k,l2) Respectively representing the l th two adjacent symbols occupied by the DMRS estimated in step 71And l2The channel impulse response of the k-th subcarrier above.
As shown in fig. 3, in the gaussian channel, when 2 users and 4 users multiplex the same time-frequency resource, the variation curve of the system performance with the signal-to-noise ratio, and under the condition of 2 users multiplexing, when the signal-to-noise ratio is above-21 dB, the system error rate is reduced to 10-4In the following, under the condition of multiplexing 4 users, when the signal-to-noise ratio is more than-19.5 dB, the system error rate is reduced to 10-4The following. At 10-4By way of limitation, the system performance for the 4 user scenario is at a loss compared to the system performance for the 2 user scenarioApproximately 1.5 dB.
As shown in fig. 4, in the EPA channel, when 2 users and 4 users multiplex the same time-frequency resource, the system performance varies with the snr, and in the case of 2 users multiplexing, when the snr is above 5dB, the system error rate is reduced to 10-4The following. Under the condition of multiplexing 4 users, when the signal-to-noise ratio is more than 7.5dB, the system bit error rate is reduced to 10-4The following. At 10-4By way of limitation, the system performance for the 4 user scenario is approximately 2.5dB less than the system performance for the 2 user scenario.
It can be seen that the performance of the present invention is very outstanding, and the error rate is low under both gaussian channel and EPA channel. Therefore, the invention can be widely applied to the project development of the PUCCH of the 5G system.
Those skilled in the art will appreciate that all or part of the steps in the methods of the above embodiments may be implemented by associated hardware instructed by a program, which may be stored in a computer-readable storage medium, and the storage medium may include: ROM, RAM, magnetic or optical disks, and the like.
The above-mentioned embodiments, which further illustrate the objects, technical solutions and advantages of the present invention, should be understood that the above-mentioned embodiments are only preferred embodiments of the present invention, and should not be construed as limiting the present invention, and any modifications, equivalents, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (9)

1. A channel estimation method based on multi-user multiplexing of 5G is suitable for an uplink control channel transmission format 4 of a 5G system; characterized in that the method comprises the following steps:
step 1, sending uplink control information by adopting a sending format 4, and decomposing frequency domain cyclic shift in a demodulation reference signal into symbol frequency domain cyclic shift and user frequency domain cyclic shift after the uplink control information reaches a base station end through channel transmission; and the demodulation reference signal matrix of the receiving end
Figure FDA0002899543160000011
Is constructed in such a way that
Figure FDA0002899543160000012
Dimension special matrix
Figure FDA0002899543160000013
Step 2, adopting a method based on linear minimum mean square error to carry out alignment on the special matrix
Figure FDA0002899543160000014
Is processed to obtain
Figure FDA0002899543160000015
Dimension matrix
Figure FDA0002899543160000016
Step 3, to the obtained
Figure FDA0002899543160000017
Each row in the matrix
Figure FDA0002899543160000018
Discrete cosine transform of points to obtain
Figure FDA0002899543160000019
Dimension matrix
Figure FDA00028995431600000110
Step 4, matrix after discrete cosine transform
Figure FDA00028995431600000111
Each row in the sequence is subjected to the inverse extensible discrete cosine transform to obtain
Figure FDA00028995431600000112
Dimension matrix
Figure FDA00028995431600000113
Step 5, obtaining an inverse transformation matrix
Figure FDA00028995431600000114
Of each row, obtaining the effective value of
Figure FDA00028995431600000115
Of (2) matrix
Figure FDA00028995431600000116
According to a matrix
Figure FDA00028995431600000117
Estimating a channel impulse response matrix of symbols occupied by a plurality of user demodulation reference signals; carrying out time domain linear interpolation on the data signals to obtain signal impulse response of each data signal position;
wherein N isTIndicating the number of multiplexed users of transmission format 4;
Figure FDA00028995431600000118
indicating the number of sub-carriers on one physical resource block.
2. The channel estimation method based on 5G multiuser multiplexing of claim 1, wherein the signal matrix of the receiving end is
Figure FDA00028995431600000119
Comprises the signal r received by removing the respective subcarriers on the respective symbolsl(i) Symbol frequency domain cyclic shift a inlThereby determining the signal matrix of the receiving end
Figure FDA00028995431600000120
Specifically, the calculation is performed by the following formula:
Figure FDA0002899543160000021
Figure FDA0002899543160000022
wherein the content of the first and second substances,
Figure FDA0002899543160000023
expressed as the received computation signal on the ith subcarrier on the ith symbol;
Figure FDA0002899543160000024
αlrepresenting the cyclic shift of the l-th symbol, alphatRepresenting the frequency domain cyclic shift of the t-th user;
Figure FDA0002899543160000025
represents a ZC sequence; h isl,t(i) Denotes the channel impulse response, z, of the t-th user at the i-th sub-carrier on the l-th symboll,t(i) Additive white gaussian noise representing the t-th user;
Figure FDA0002899543160000026
a frequency representation that is a cyclic shift of the frequency domain at the ith subcarrier on the ith symbol; h isl,s(i) Denotes the channel impulse response, z, of the ZC sequence at the ith subcarrier on the ith symboll,s(i) Additive white Gaussian noise representing a ZC sequence; denotes conjugation; r isl(i) Representing the received signal on the ith subcarrier on the ith symbol.
3. The channel estimation method based on 5G multiuser multiplexing of claim 2, characterized in that the ith symbolIs said to be represented as:
Figure FDA0002899543160000027
the frequency domain cyclic shift of the nth user is expressed as:
Figure FDA0002899543160000028
wherein the content of the first and second substances,
Figure FDA0002899543160000029
nsindicates the time slot number of the current uplink control channel in the data frame,
Figure FDA00028995431600000210
indicating the number of symbols contained in each slot, lrIndicates the position of the current symbol relative to the first symbol for transmitting the uplink control channel, l indicates the position of the current symbol in the whole time slot, and c indicates the length of
Figure FDA00028995431600000211
A pseudo-random sequence of (a); m is0＝0，mcsRepresenting values assigned by the base station to different users.
4. The channel estimation method based on 5G multiuser multiplexing as claimed in claim 2, characterized in that the special matrix
Figure FDA00028995431600000212
Is constructed in a manner that includes
Figure FDA00028995431600000213
Wherein the content of the first and second substances,
Figure FDA00028995431600000214
representation matrix
Figure FDA00028995431600000215
Order of the n-th line of (1)Column, is represented as
Figure FDA00028995431600000216
5. The method for channel estimation based on 5G multiuser multiplexing according to claim 2, wherein the step 2 comprises
Figure FDA00028995431600000217
Wherein the content of the first and second substances,
Figure FDA0002899543160000031
Figure FDA0002899543160000032
to represent
Figure FDA0002899543160000033
In the ith row of the autocorrelation matrix, RSNRepresents the signal-to-noise ratio of the channel, I represents an identity matrix, β { | x {, E { | x {, q {,/h {k|2}·E{|1/xk|2}，xkRepresenting the actual complex-valued signal; e {. denotes expectation;
Figure FDA0002899543160000034
representing special matrices
Figure FDA0002899543160000035
The k-th row of (1).
6. The method of claim 2, wherein the step 3 comprises
Figure FDA0002899543160000036
Wherein D is
Figure FDA0002899543160000037
A discrete cosine transform matrix of points, in which matrix D each element (m, n) comprises
Figure FDA0002899543160000038
Wherein the content of the first and second substances,
Figure FDA0002899543160000039
Anrepresenting the magnitude in a discrete cosine transform, when n is 0,
Figure FDA00028995431600000310
when n ≠ 0, it is determined,
Figure FDA00028995431600000311
7. the method of claim 2, wherein the step 4 comprises
Figure FDA00028995431600000312
Formula (I) wherein
Figure FDA00028995431600000313
Is composed of
Figure FDA00028995431600000314
The dimension matrix is a matrix of dimensions,
Figure FDA00028995431600000315
is composed of
Figure FDA00028995431600000316
The dimension matrix is a matrix of dimensions,
Figure FDA00028995431600000317
the matrix elements (m, n) in (1) include
Figure FDA00028995431600000318
Wherein the content of the first and second substances,
Figure FDA00028995431600000319
M′＝M/NT，m＝0,1,…,M/NT，l＝-(NT-1), …,0, …, M-1, when M is 0,
Figure FDA00028995431600000320
when m is not equal to 0, the ratio of m,
Figure FDA00028995431600000321
8. the method as claimed in claim 2, wherein the step 5 of estimating the channel impulse response matrix of the symbols occupied by the multiple user demodulation reference signals comprises the step of estimating the channel impulse response matrix of the symbols occupied by the multiple user demodulation reference signals
Figure FDA00028995431600000322
The matrix takes the effective value of each row and represents it as
Figure FDA00028995431600000323
Wherein the content of the first and second substances,
Figure FDA00028995431600000324
to represent
Figure FDA00028995431600000325
The valid value of row i;
Figure FDA00028995431600000326
to represent
Figure FDA00028995431600000327
The value of row i;
Figure FDA00028995431600000328
i denotes an identity matrix and 0 denotes a zero matrix, then the estimation value of the channel impulse response matrix at the demodulation reference signal for each user is found as:
Figure FDA00028995431600000329
Figure FDA00028995431600000330
representation matrix
Figure FDA00028995431600000331
The conjugate transpose of (a) is performed,
Figure FDA00028995431600000332
is composed of
Figure FDA00028995431600000333
A dimension matrix.
9. The method according to claim 2, wherein the step 5 of obtaining the signal impulse response of each data signal position comprises obtaining the channel impulse response at the kth subcarrier (k, l) of the ith symbol in the data signal by using a time-domain linear interpolation algorithm, which is expressed as:
Figure FDA0002899543160000041
wherein Hp(k,l1) And Hp(k,l2) Respectively representing the estimated two adjacent symbols occupied by the demodulation reference signal1And l2The channel impulse response of the k-th subcarrier above.
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