CN112511270A - Cooperative receiving method and system based on air interface information fusion - Google Patents

Cooperative receiving method and system based on air interface information fusion Download PDF

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CN112511270A
CN112511270A CN202011157897.0A CN202011157897A CN112511270A CN 112511270 A CN112511270 A CN 112511270A CN 202011157897 A CN202011157897 A CN 202011157897A CN 112511270 A CN112511270 A CN 112511270A
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刘安
刘冠颖
赵民建
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Zhejiang University ZJU
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Zhejiang University ZJU
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0009—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the channel coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/16—Circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0045—Arrangements at the receiver end
    • H04L1/0054—Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms

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Abstract

The invention discloses a cooperative receiving method and a system based on air interface information fusion, wherein a second channel coding signal is obtained by eliminating phase rotation of a channel to a first channel coding signal; selecting a cooperative receiver in a range of setting the signal-to-noise ratio of the second channel coding signal, controlling the cooperative receiver to calculate the log-likelihood ratio, and transmitting the log-likelihood ratio information of the (Q-1) cooperative receivers to the rest cooperative receivers in a mode of air interface information fusion; and controlling the remaining cooperative receivers to integrate the log-likelihood ratio information of the Q cooperative receivers, and decoding the first channel coding signal according to the integrated log-likelihood ratio information to obtain a decoding result. The invention can greatly reduce the cooperative decoding time delay, reduce the error rate, support more receivers to cooperate and improve the expandability of the system.

Description

Cooperative receiving method and system based on air interface information fusion
Technical Field
The invention relates to the technical field of wireless communication, in particular to a cooperative receiving method and a cooperative receiving system based on air interface information fusion.
Background
In recent years, cooperative communication technology has become one of the hot research fields of wireless communication. The cooperative reception technique combines the received signals of multiple receivers in a wireless network to form a virtual antenna array to increase diversity and power gain, thereby increasing the probability of successfully decoding noisy transmissions, with the potential of improving wireless network capacity and error rate performance. Cooperative reception may also result in increased communication range, increased data rate, and/or reduced transmit power.
Existing cooperative reception techniques can be broadly classified into the following categories:
a. each receiver broadcasts its received signal over the local area network and then performs maximum ratio combining at the fusion center to achieve diversity gain. However, this method has very high requirements on the throughput of the network, and it is difficult for the actual network to meet the requirements.
b. Hard decision information is simply exchanged between some or all nodes between the receivers, and each receiver performs decoding demodulation according to itself and the received hard decision information. Although the method has low requirements on the throughput of the network, exchanging hard decision information may cause a certain loss of the performance of the final decoding.
c. Each receiver in the receive cluster locally demodulates the transmission and generates log-likelihood ratios. All receiving nodes (or a subset of nodes with better channel quality) quantize their log-likelihood ratios and broadcast all their quantized values over the network to the other receiving nodes in the cluster. Each receiving node then combines the information received over the network with its local unquantized log-likelihood ratios and passes these results to its local block decoder for decoding. If any receiving node successfully decodes the message, it forwards the decoded message to other receiving nodes in the cluster over the network. Each receiving node will transmit log-likelihood ratio values through the network, and in order to avoid inter-node interference, each node needs to allocate orthogonal radio resources. When the number of the receivers is large, the calculation waiting time delay is greatly increased, so that the problem of poor network expansibility occurs.
Therefore, the conventional cooperative reception technology has the defects of high error rate, prolonged interaction time, poor network expansibility and the like.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.
Therefore, an object of the present invention is to provide a cooperative receiving method based on air interface information fusion, in which four major parts, that is, a first encoded signal is sent by a transmitter, a cooperative receiver calculates a log-likelihood ratio, the cooperative receiver performs air interface fusion on the log-likelihood ratio, and the cooperative receiver performs decoding by using the air interface fused log-likelihood ratio information, so that cooperative decoding delay can be greatly reduced, an error rate can be reduced, more receivers can be supported to cooperate, and system expandability can be improved.
Another objective of the present invention is to provide a cooperative receiving system based on air interface information fusion.
In order to achieve the above object, an embodiment of the present invention provides a cooperative receiving method based on air interface information fusion, including the following steps: simultaneously sending first channel coding signals to N cooperative receivers, wherein N is a set constant; eliminating the phase rotation of the first channel coding signal by the channel to obtain a second channel coding signal; calculating the signal-to-noise ratio of second channel coding signals of the N cooperative receivers, selecting Q cooperative receivers in a set signal-to-noise ratio range from the N cooperative receivers, and calculating a log-likelihood ratio according to the second channel coding signals of the Q cooperative receivers, wherein Q is a positive integer and is less than or equal to N; randomly selecting one cooperative receiver from the Q cooperative receivers as a fusion receiver, and transmitting the log-likelihood ratios of the rest (Q-1) cooperative receivers to the fusion receiver in a way of air interface information fusion; controlling the fusion receiver to integrate log-likelihood ratio information of the Q cooperative receivers, and decoding the first channel coding signal according to the integrated log-likelihood ratio information to obtain a decoding result; broadcasting the decoding result to (N-1) cooperative receivers other than the fusion receiver.
According to the cooperative receiving method based on air interface information fusion, a second channel coding signal is obtained by eliminating phase rotation of a channel to a first channel coding signal; selecting a cooperative receiver in a range of setting the signal-to-noise ratio of the second channel coding signal, controlling the cooperative receiver to calculate the log-likelihood ratio, and transmitting the log-likelihood ratio information of the (Q-1) cooperative receivers to the rest cooperative receivers in a mode of air interface information fusion; controlling the remaining cooperative receivers to integrate the log-likelihood ratio information of the Q cooperative receivers, and decoding the first channel coding signal according to the integrated log-likelihood ratio information to obtain a decoding result; therefore, the cooperative decoding time delay can be greatly reduced, the error rate is reduced, more receivers are supported to cooperate, and the expandability of the system is improved.
In addition, the cooperative receiving method based on air interface information fusion according to the above embodiment of the present invention may further have the following additional technical features:
further, in an embodiment of the present invention, the removing the phase rotation of the first channel-coded signal by the channel to obtain a second channel-coded signal includes: transmitting pilot signals to the N cooperative receivers; estimating a channel by utilizing a least square method or a minimum mean square error method according to the pilot signal, and calculating the signal-to-noise ratio of the pilot signal according to a channel estimation result; transmitting the first channel-coded signal to the N cooperative receivers; and eliminating the phase rotation of the first channel coding signal by utilizing the signal-to-noise ratio of the pilot signal to obtain the second channel coding signal.
Further, in an embodiment of the present invention, the second channel-coded signal is:
Yi[m,l]＝|hi[m]X[m,l]+Wi[m,l]，
wherein, Yi[m,l]The ith transmitted symbol, h, in the mth block of the second channel-coded signal represented as the ith cooperative receiveri[m]Representing the forward link complex channel, Xm, l, through which the mth block of the first channel-encoded signal passes to the ith cooperative receiver]A first transmission symbol in the mth block signal represented as the first channel-coded signal, wherein the mth block signal of the first channel-coded signal has k transmission symbols, and the k transmission symbols are represented by X ═ { X ═ in a set1,...,xk}，X[m,l]Equal probability selection from the set X, Wi[m,l]Denoted as ith protocolAs noise, W, generated by the receiver after baseband matching filtering the ith transmission symbol in the mth block signal of the second channel coding signali[m,l]Obedience mean 0, variance N0Complex gaussian distribution.
Further, in an embodiment of the present invention, a calculation formula of the signal-to-noise ratio of the second channel coded signal is:
ρi＝|hi[m]χ2Es/σi 2，
Figure BDA0002743322550000031
where ρ isiRepresenting the signal-to-noise ratio, h, of the mth block signal in said second channel-coded signal of the ith cooperative receiveri[m]Expressed as the forward link complex channel, σ, traveled by the mth block signal of the first channel-encoded signal to the ith cooperative receiveri 2Expressed as the noise variance, X [ m, l, generated by the i-th cooperative receiver]The ith transmission symbol in the mth block signal represented as the first channel-coded signal, EsRepresents the average energy of each transmitted symbol in the mth block of the first channel-coded signal, E (-) represents the mean value, and k represents the number of transmitted symbols in the mth block of the first channel-coded signal.
Further, in an embodiment of the present invention, the calculation formula of the log-likelihood ratio is:
Figure BDA0002743322550000032
wherein the content of the first and second substances,
Figure BDA0002743322550000033
denoted as the ith cooperative receiver, on the basis of said second channel-coded signal Yi[m,l]Calculated with respect to transmitted symbol xkLog likelihood ratio of (1), xlFor transmitting a set of symbols X ═ X1,...,xkThe l-th transmission symbol in (1) }, pY/X(Yi[m,l])＝xl|X[m,l]＝xkExpressed as the probability, p, of obtaining the ith symbol of the symbol set after demodulation by the ith cooperative receiver under the condition that the transmitter transmits the kth symbol of the mth block of the first channel-coded signaliIndicating the probability of error.
Further, in an embodiment of the present invention, the transmitting log-likelihood ratios of the remaining (Q-1) cooperative receivers to the fused receiver by way of air interface information fusion includes: multiplying the log-likelihood ratio of the (Q-1) cooperative receivers by a normalization factor b to obtain a normalized signal, and repeatedly sending the normalized signal to the fusion receiver for Z times, wherein Z is a set constant; receiving the normalized signal by the fusion receiver through a normalization factor a to obtain a received signal, wherein the received signal is represented as:
Figure BDA0002743322550000041
wherein the content of the first and second substances,
Figure BDA0002743322550000042
means that the z-th received signal of the fusion receiver is the sum of log-likelihood ratios of the (Q-1) cooperative receivers with respect to the k-th transmitted symbol,
Figure BDA0002743322550000043
for the channel coefficient between the ith user and the converged receiver, nzWhite gaussian noise generated for the fused receiver,
Figure BDA0002743322550000044
indicating that the ith cooperative receiver is transmitting symbol xkLog-likelihood ratio of (1), normalization factor
Figure BDA0002743322550000045
And azReceiving signals according to Z times
Figure BDA0002743322550000046
Sum of the smallest received signal and the log-likelihood ratio values of the (Q-1) receivers for the k-th transmitted symbol
Figure BDA0002743322550000047
The mean square error of (a) is jointly designed.
Further, in an embodiment of the present invention, the controlling the fusion receiver to integrate log-likelihood ratio information of the Q cooperative receivers includes: controlling the fusion receiver to combine the received signals of Z times to obtain final log-likelihood ratio information, wherein the final log-likelihood ratio information is as follows:
Figure BDA0002743322550000048
the final log likelihood ratio information r is processedkLog-likelihood ratio with said fused receiver
Figure BDA0002743322550000049
Adding to obtain an integrated set X { X } of transmission symbols1,...,xkLog-likelihood ratio information of the kth symbol in
Figure BDA00027433225500000410
Further, in an embodiment of the present invention, the decoding the first channel coded signal according to the integrated log-likelihood ratio information to obtain a decoding result includes: determining a set of transmit symbols X ═ X1,…,xkThe maximum value of log likelihood ratio information after air interface fusion is carried out on each sending symbol in the symbol array; determining a position number of the ith transmission symbol in the mth block signal corresponding to the first channel coding signal in the set X according to the maximum value of the log-likelihood ratio information; namely:
Figure BDA00027433225500000411
wherein k is*Is the firstThe position serial number of the ith transmission symbol in the mth block signal of the channel coding signal in the transmission set X; determining, according to the position sequence number, that a decoding result obtained by the fusion receiver is:
Figure BDA00027433225500000412
wherein the content of the first and second substances,
Figure BDA00027433225500000413
denoted as kth in the set of transmitted symbols X*The transmission symbol of the position sequence number.
In order to achieve the above object, an embodiment of another aspect of the present invention provides a cooperative receiving system based on air interface information fusion, including: a transmitter for simultaneously transmitting first channel coded signals to N cooperative receivers, where N is a set constant; the cooperative receiver is used for eliminating the phase rotation of the first channel coding signal by a channel to obtain a second channel coding signal; the log-likelihood ratio calculation module is used for calculating the signal-to-noise ratio of the second channel coding signals of the N cooperative receivers, selecting Q cooperative receivers in a set signal-to-noise ratio range from the N cooperative receivers, and calculating the log-likelihood ratio according to the second channel coding signals of the Q cooperative receivers, wherein Q is a positive integer and Q is less than or equal to N; an empty information fusion transmission module, configured to select one cooperative receiver from the Q cooperative receivers as a fusion receiver arbitrarily, and transmit the log-likelihood ratios of the remaining (Q-1) cooperative receivers to the fusion receiver in an empty information fusion manner; the information integration module is used for controlling the fusion receiver to integrate the log-likelihood ratio information of the Q cooperative receivers; the decoding module is used for decoding the first channel coding signal according to the integrated log-likelihood ratio information to obtain a decoding result; a propagation module for broadcasting the decoding result to (N-1) cooperative receivers other than the fusion receiver.
In the cooperative receiving system based on the air interface information fusion, a second channel coding signal is obtained by eliminating the phase rotation of a channel to a first channel coding signal; selecting a cooperative receiver in a range of setting the signal-to-noise ratio of the second channel coding signal, controlling the cooperative receiver to calculate the log-likelihood ratio, and transmitting the log-likelihood ratio information of the (Q-1) cooperative receivers to the rest cooperative receivers in a mode of air interface information fusion; controlling the remaining cooperative receivers to integrate the log-likelihood ratio information of the Q cooperative receivers, and decoding the first channel coding signal according to the integrated log-likelihood ratio information to obtain a decoding result; therefore, the cooperative decoding time delay can be greatly reduced, the error rate is reduced, more receivers are supported to cooperate, and the expandability of the system is improved.
In addition, the cooperative receiving system based on air interface information fusion according to the above embodiment of the present invention may further have the following additional technical features:
further, in an embodiment of the present invention, the air interface information fusion transmission module includes: a normalized information sending module, configured to repeatedly send a normalized signal obtained by multiplying the log-likelihood ratio of the (Q-1) cooperative receivers by a normalization factor b to the fusion receiver Z times, where Z is a set constant; and the normalized information receiving module is used for receiving the normalized signal by the fusion receiver through a normalization factor a to obtain a received signal.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
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The foregoing and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a flowchart of a cooperative receiving method based on air interface information fusion according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a cooperative receiving system based on air interface information fusion according to an embodiment of the present invention;
fig. 3 is a diagram illustrating a relationship between a transmitter and a cooperative receiver in a cooperative receiving system based on air interface information fusion according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
The invention aims to provide a cooperative receiving method and a cooperative receiving system based on air interface information fusion, so as to support the mutual cooperation of more cooperative receivers, reduce the error rate and the decoding delay and improve the expandability of the system.
The following describes a cooperative receiving method and system based on air interface information fusion according to an embodiment of the present invention with reference to the accompanying drawings, and first, a cooperative receiving method based on air interface information fusion according to an embodiment of the present invention will be described with reference to the accompanying drawings.
Fig. 1 is a flowchart of a cooperative receiving method based on air interface information fusion according to an embodiment of the present invention.
As shown in fig. 1, the cooperative receiving method and system based on air interface information fusion includes the following steps:
in step S101, the first channel-coded signals are simultaneously transmitted to N cooperative receivers, where N is a set constant.
Wherein the N cooperative receivers are reception clusters.
In step S102, the phase rotation of the first channel encoded signal by the channel is removed, and a second channel encoded signal is obtained.
Specifically, step S102 includes:
step S21, sending pilot signals to N cooperative receivers;
step S22, estimating the channel by using least square method or minimum mean square error method according to the pilot signal, and calculating the signal-to-noise ratio of the pilot signal according to the channel estimation result;
step S23, transmitting the first channel coding signal to N cooperative receivers;
step S24, the signal-to-noise ratio of the pilot signal is used to eliminate the phase rotation of the first channel encoded signal, so as to obtain the second channel encoded signal.
By eliminating the phase rotation of the first channel coding signal by the channel, the signal received by the cooperative receiver can be ensured to be completely consistent with the signal sent by the transmitter, and further, when the signal sent by the transmitter is decoded by utilizing the log-likelihood ratio of the received signal of the cooperative receiver, the accuracy of the decoding result can be improved, and the error rate can be reduced.
In one embodiment of the invention, the second channel encoded signal is represented as:
Yi[m,l]＝|hi[m]|X[m,l]+Wi[m,l]
wherein, Yi[m,l]Denoted as the ith transmitted symbol in the mth block of the second channel-coded signal of the ith cooperative receiver, hi[m]Expressed as the forward link complex channel, Xm, l, traversed by the mth block of the first channel-encoded signal to the ith cooperative receiver]The first transmission symbol in the mth block signal of the first channel-coded signal is represented by k transmission symbols, where the k transmission symbols are represented by X ═ X in the set1,…,xk}，X[m,l]Equal probability selection from the set X, Wi[m,l]Denoted as the noise, W, generated by the i-th cooperative receiver after baseband matching filtering the l-th transmission symbol in the m-th block signal of the second channel coded signali[m,l]Obedience mean 0, variance N0Complex Gaussian distribution of (i.e. W)i[m,l]～CN(0,N0)。
In step S103, signal-to-noise ratios of the second channel coded signals of the N cooperative receivers are calculated, Q cooperative receivers within a set signal-to-noise ratio range are selected from the N cooperative receivers, and log-likelihood ratios are calculated according to the second channel coded signals of the Q cooperative receivers, where Q is a positive integer and Q is less than or equal to N.
In one embodiment of the present invention, the snr of the second channel-coded signal is calculated by the following formula:
ρi＝|hi[m]|2Es/σi 2
Figure BDA0002743322550000071
where ρ isiRepresenting the signal-to-noise ratio, h, of the mth block signal in the second channel-coded signal of the ith cooperative receiveri[m]Representing the forward link complex channel through which the mth block signal in the first channel encoded signal travels to the ith cooperative receiver,
Figure BDA0002743322550000072
expressed as the noise variance, X m, l, produced by the ith cooperative receiver]The l transmission symbol in the m-th block signal, denoted as the first channel-coded signal, EsRepresents the average energy of each transmitted symbol in the mth block of the first channel-coded signal, E (-) represents the mean value, and k represents the number of transmitted symbols in the mth block of the first channel-coded signal.
The formula for calculating the log-likelihood ratio is as follows:
Figure BDA0002743322550000073
wherein the content of the first and second substances,
Figure BDA0002743322550000074
denoted as the ith cooperative receiver, encoding the signal Y from the second channeli[m,l]Calculated with respect to transmitted symbol xkLog likelihood ratio of (1), xlFor transmitting a set of symbols X ═ X1,…,xkThe l-th transmission symbol in (1) }, pY/X(Yi[m,l])＝xl|X[m,l]＝xkExpressed as the probability, p, of obtaining the ith symbol of the symbol set after demodulation by the ith cooperative receiver under the condition that the transmitter transmits the kth symbol of the mth block of the first channel-coded signaliThe probability of an error is indicated and,
Figure BDA0002743322550000075
v is a set constant.
Probability of error piRelated to the channel transition probability. For example, for a vector having χ ═ x1,x2The BPSK modulation mode of the digital signal is adopted,
Figure BDA0002743322550000076
for a compound having x ═ x1,x2,x3,x4The QPSK modulation mode of the digital signal is adopted,
Figure BDA0002743322550000077
wherein the content of the first and second substances,
Figure BDA0002743322550000078
erfc (β) ═ 1-erf (β), erf is a cumulative function of the standard normal distribution, i.e.:
Figure BDA0002743322550000079
the log-likelihood ratio is calculated by the cooperative receivers within the set signal-to-noise ratio range, so that the time for calculating the log-likelihood ratio by all the cooperative receivers can be shortened, and the time delay is reduced; and the signal-to-noise ratio range of the second channel coding signal is set, so that the influence of a cooperative receiver with low signal-to-noise ratio can be reduced, the log-likelihood ratio of the cooperative receiver with high signal-to-noise ratio is used for decoding, the decoding accuracy can be improved, and the error rate can be reduced.
In step S104, one cooperative receiver is arbitrarily selected from the Q cooperative receivers as a fusion receiver, and the log-likelihood ratios of the remaining (Q-1) cooperative receivers are transmitted to the fusion receiver by way of null information fusion.
Specifically, step S104 includes:
step S41, a normalized signal obtained by multiplying the log-likelihood ratio of the (Q-1) cooperative receivers by a normalization factor b is repeatedly sent to the fusion receiver for Z times, wherein Z is a set constant;
step S42, the fusion receiver receives the normalized signal through the normalization factor a to obtain a received signal; the received signal is represented as:
Figure BDA0002743322550000081
wherein r isk zThe represented fusion receiver receives the signal for the z-th time as the sum of the log-likelihood ratios of (Q-1) cooperative receivers with respect to the k-th transmitted symbol,
Figure BDA0002743322550000082
for the channel coefficient between the ith user and the convergence receiver, nzIn order to fuse the white gaussian noise generated by the receiver,
Figure BDA0002743322550000083
indicating that the ith cooperative receiver is transmitting symbol xkLog-likelihood ratio of (1), normalization factor
Figure BDA0002743322550000084
And azReceiving signals according to Z times
Figure BDA0002743322550000085
Sum of the smallest received signal and the log-likelihood ratio values of (Q-1) receivers for the k-th transmitted symbol
Figure BDA0002743322550000086
The mean square error of (a) is jointly designed,
Figure BDA0002743322550000087
p' is the peak power limit of each (Q-1) cooperative receiver. Without loss of generality, the channel passed by (Q-1) cooperative receivers at the z-th transmission
Figure BDA0002743322550000088
That is, it can always ensure that users are sorted according to their channel strengths, and ensure that the channel strengths passed by (Q-1) cooperative receivers are increased in sequence when the z-th retransmission is performed. To achieve a smaller MSE, the normalization factor
Figure BDA0002743322550000089
And azCan be designed as
Figure BDA00027433225500000810
Since the sum of log-likelihood ratios of the (Q-1) cooperative receivers received by the fusion receiver for the z-th transmitted symbol
Figure BDA00027433225500000811
In the presence of noise, the received signals are further reduced by combining after multiple repeated transmissions
Figure BDA00027433225500000812
Sum of log-likelihood ratio values for the kth transmitted symbol with (Q-1) cooperative receivers
Figure BDA00027433225500000813
The mean square error between the two signals improves the signal-to-noise ratio of the signals received by the fusion receiver, so that the influence of noise can be reduced when the received signals are subsequently used for decoding, the decoding accuracy is improved, and the error rate is reduced.
The air interface information fusion is directly carried out on the log-likelihood ratio by the superposition characteristic of the wireless channel through the cooperative receivers, the fused receivers only need to decode according to the sum of the log-likelihood ratios of the Q receivers without paying attention to LLR of each receiver, the situation that each cooperative receiver needs to broadcast the log-likelihood ratio of the cooperative receiver to other receivers in a time-sharing mode can be avoided, when the number of the cooperative receivers is increased and the channel condition is poor, LLR transmission delay is greatly increased, the defects of low LLR transmission efficiency, large cooperative decoding delay and poor system expandability can be caused, the transmission efficiency of the log-likelihood ratio is improved, the cooperative decoding delay is reduced, and the expandability of the system is improved.
In step S105, the fusion receiver is controlled to integrate log-likelihood ratio information of the Q cooperative receivers, and decode the first channel coded signal according to the integrated log-likelihood ratio information to obtain a decoding result.
Specifically, step S105 includes:
step S51, controlling the fusion receiver to merge the Z times of received signals to obtain the final log-likelihood ratio information
Figure BDA0002743322550000091
Step S52, final log likelihood ratio information rkLog-likelihood ratio with fused receiver
Figure BDA0002743322550000092
Adding to obtain an integrated set X { X } of transmission symbols1,…,xkLog-likelihood ratio information of the kth symbol in
Figure BDA0002743322550000093
Step S53, determining transmission symbol set X ═ { X ═ X1,…,xkThe maximum value of the log-likelihood ratio information after air interface fusion of each sending symbol is
Figure BDA0002743322550000094
Step S54, determining the position number of the ith sending symbol in the mth block signal corresponding to the first channel coding signal in the set X according to the maximum value of the log-likelihood ratio information; namely:
Figure BDA0002743322550000095
wherein k is*The position sequence number of the ith transmission symbol in the mth block signal of the first channel coding signal in the transmission set X is coded;
step S55, determining, according to the position sequence number, that the decoding result obtained by the fusion receiver is:
Figure BDA0002743322550000096
wherein
Figure BDA0002743322550000097
Expressed as set X of transmission symbolsKth*The transmission symbol of the position sequence number.
It should be noted that the transmission symbol corresponding to the maximum value of the log-likelihood ratio information is the most likely symbol to be transmitted by the transmitter, and decoding is performed.
In step S106, the decoding result is broadcast to (N-1) cooperative receivers other than the fusion receiver.
According to the cooperation receiving method based on empty information fusion provided by the embodiment of the invention, the signals sent by the transmitter are processed, the phase rotation of the channels to the sent signals is eliminated, the signals received by the cooperation receiver can be ensured to be completely consistent with the signals sent by the transmitter, and further, when the signals sent by the transmitter are decoded by utilizing the log-likelihood ratio of the received signals of the cooperation receiver, the accuracy of a decoding result can be improved, and the error rate is reduced; by selecting the cooperative receivers in the set signal-to-noise ratio range to calculate the log-likelihood ratio, the time for calculating the log-likelihood ratio of all the cooperative receivers can be shortened, and the time delay is reduced; the air interface fusion is carried out on the log-likelihood ratio through the cooperative receivers, the fusion receivers decode by utilizing the air interface fused log-likelihood ratio information, namely the air interface information fusion is directly carried out on the log-likelihood ratio by utilizing the superposition characteristic of a wireless channel, the fusion receivers only need to decode according to the sum of the log-likelihood ratios of Q receivers without paying attention to LLR of each receiver, the situation that each cooperative receiver needs to broadcast the log-likelihood ratio of the fusion receivers to other receivers in a time-sharing mode can be avoided, when the number of the cooperative receivers is increased and the channel condition is poor, the LLR transmission delay is greatly increased, the defects of low LLR transmission efficiency, large LLR transmission delay and poor system expandability among the cooperative receivers can be overcome, the transmission efficiency of the log-likelihood ratio is improved, the cooperative decoding delay is reduced.
Next, a cooperative receiving system based on air interface information fusion according to an embodiment of the present invention is described with reference to the drawings.
Fig. 2 is a schematic structural diagram of a cooperative receiving system based on air interface information fusion according to an embodiment of the present invention.
As shown in fig. 2, the cooperative receiving system based on air interface information fusion includes: the device comprises a transmitter 100, a cooperative receiver 200, a log-likelihood ratio calculation module 300, an air interface information fusion transmission module 400, an information integration module 500, a decoding module 600 and a propagation module 700.
The transmitter 100 is configured to simultaneously transmit a first channel coded signal to N cooperative receivers, where N is a set constant; the cooperative receiver 200 is configured to eliminate phase rotation of the first channel encoded signal by the channel to obtain a second channel encoded signal; the log-likelihood ratio calculation module 300 is configured to calculate signal-to-noise ratios of second channel coded signals of the N cooperative receivers, select Q cooperative receivers in a set signal-to-noise ratio range from the N cooperative receivers, and calculate a log-likelihood ratio according to the second channel coded signals of the Q cooperative receivers, where Q is a positive integer and Q is not greater than N; the air interface information fusion transmission module 400 is configured to select one cooperative receiver from the Q cooperative receivers as a fusion receiver, and transmit the log-likelihood ratios of the remaining (Q-1) cooperative receivers to the fusion receiver in an air interface information fusion manner; the information integration module 500 is used for controlling the fusion receiver to integrate log-likelihood ratio information of the Q cooperative receivers; a decoding module 600, configured to decode the first channel coded signal according to the integrated log-likelihood ratio information to obtain a decoding result; the propagation module 700 is used to broadcast the decoding results to (N-1) cooperative receivers other than the fusion receiver.
It can be understood that, in the system 10 according to the embodiment of the present invention, the transmitter transmits the first encoded signal, the cooperative receiver calculates the log-likelihood ratio, the cooperative receiver performs air interface fusion on the log-likelihood ratio, and the cooperative receiver performs decoding using the air interface fused log-likelihood ratio information, which can greatly reduce the cooperative decoding delay, reduce the error rate, support more receivers to cooperate, and improve the scalability of the system. A relationship diagram of a transmitter and a cooperative receiver in a cooperative receiving system based on air interface information fusion is shown in fig. 3.
Further, in an embodiment of the present invention, the air interface information fusion transmission module includes: the device comprises a normalization information sending module and a normalization information receiving module.
The normalization information sending module is used for repeatedly sending a normalization signal obtained by multiplying the log-likelihood ratio of the (Q-1) cooperative receivers by the normalization factor b to the fusion receiver for Z times, wherein Z is a set constant; and the normalization information receiving module is used for receiving the normalization signal by the fusion receiver through the normalization factor a to obtain a received signal.
It should be noted that the explanation of the embodiment of the cooperative receiving method based on air interface information fusion also applies to the cooperative receiving system based on air interface information fusion of the embodiment, and is not repeated here.
According to the cooperative receiving system based on the empty information fusion, provided by the embodiment of the invention, the phase rotation of the channel to the transmitted signal is eliminated by processing the signal transmitted by the transmitter, so that the signal received by the cooperative receiver is completely consistent with the signal transmitted by the transmitter, and further, when the signal transmitted by the transmitter is decoded by utilizing the log-likelihood ratio of the received signal of the cooperative receiver, the accuracy of a decoding result can be improved, and the error rate is reduced; by selecting the cooperative receivers in the set signal-to-noise ratio range to calculate the log-likelihood ratio, the time for calculating the log-likelihood ratio of all the cooperative receivers can be shortened, and the time delay is reduced; the air interface fusion is carried out on the log-likelihood ratio through the cooperative receivers, the fusion receivers decode by utilizing the air interface fused log-likelihood ratio information, namely the air interface information fusion is directly carried out on the log-likelihood ratio by utilizing the superposition characteristic of a wireless channel, the fusion receivers only need to decode according to the sum of the log-likelihood ratios of Q receivers without paying attention to LLR of each receiver, the situation that each cooperative receiver needs to broadcast the log-likelihood ratio of the fusion receivers to other receivers in a time-sharing mode can be avoided, when the number of the cooperative receivers is increased and the channel condition is poor, the LLR transmission delay is greatly increased, the defects of low LLR transmission efficiency, large LLR transmission delay and poor system expandability among the cooperative receivers can be overcome, the transmission efficiency of the log-likelihood ratio is improved, the cooperative decoding delay is reduced.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (10)

1. A cooperative receiving method based on air interface information fusion is characterized by comprising the following steps:
simultaneously sending first channel coding signals to N cooperative receivers, wherein N is a set constant;
eliminating the phase rotation of the first channel coding signal by the channel to obtain a second channel coding signal;
calculating the signal-to-noise ratio of second channel coding signals of the N cooperative receivers, selecting Q cooperative receivers in a set signal-to-noise ratio range from the N cooperative receivers, and calculating a log-likelihood ratio according to the second channel coding signals of the Q cooperative receivers, wherein Q is a positive integer and is less than or equal to N;
randomly selecting one cooperative receiver from the Q cooperative receivers as a fusion receiver, and transmitting the log-likelihood ratios of the rest (Q-1) cooperative receivers to the fusion receiver in a way of air interface information fusion;
controlling the fusion receiver to integrate log-likelihood ratio information of the Q cooperative receivers, and decoding the first channel coding signal according to the integrated log-likelihood ratio information to obtain a decoding result;
broadcasting the decoding result to (N-1) cooperative receivers other than the fusion receiver.
2. The method of claim 1, wherein said removing the phase rotation of the first channel-encoded signal by the channel to obtain a second channel-encoded signal comprises:
transmitting pilot signals to the N cooperative receivers;
estimating a channel by utilizing a least square method or a minimum mean square error method according to the pilot signal, and calculating the signal-to-noise ratio of the pilot signal according to a channel estimation result;
transmitting the first channel-coded signal to the N cooperative receivers;
and eliminating the phase rotation of the first channel coding signal by utilizing the signal-to-noise ratio of the pilot signal to obtain the second channel coding signal.
3. The method of claim 2, wherein the second channel-encoded signal is:
Yi[m,l]＝|hi[m]|X[m,l]+Wi[m,l]，
wherein, Yi[m,l]The ith transmitted symbol, h, in the mth block of the second channel-coded signal represented as the ith cooperative receiveri[m]Expressed as the m-th block signal to the i-th block signal in the first channel coded signalForward link complex channel, Xm, l, traversed by a cooperative receiver]A first transmission symbol in the mth block signal represented as the first channel-coded signal, wherein the mth block signal of the first channel-coded signal has k transmission symbols, and the k transmission symbols are represented by X ═ { X ═ in a set1,…,xk}，X[m,l]Equal probability selection from the set X, Wi[m,l]Denoted as the noise, W, generated by the i-th cooperative receiver after baseband matching filtering the l-th transmission symbol in the m-th block signal of the second channel coding signali[m,l]Obedience mean 0, variance N0Complex gaussian distribution.
4. The method of claim 1, wherein the snr of the second channel-encoded signal is calculated by:
Figure FDA0002743322540000021
Figure FDA0002743322540000022
where ρ isiRepresenting the signal-to-noise ratio, h, of the mth block signal in said second channel-coded signal of the ith cooperative receiveri[m]Representing the forward link complex channel through which the mth block of signals in the first channel encoded signal passed to the ith cooperative receiver,
Figure FDA0002743322540000023
expressed as the noise variance, X [ m, l, generated by the i-th cooperative receiver]The ith transmission symbol in the mth block signal represented as the first channel-coded signal, EsRepresents the average energy of each transmitted symbol in the mth block of the first channel-coded signal, E (-) represents the mean value, and k represents the number of transmitted symbols in the mth block of the first channel-coded signal.
5. The method of claim 1, wherein the log-likelihood ratio is calculated by:
Figure FDA0002743322540000024
wherein the content of the first and second substances,
Figure FDA0002743322540000025
denoted as the ith cooperative receiver, on the basis of said second channel-coded signal Yi[m,l]Calculated with respect to transmitted symbol xkLog likelihood ratio of (1), xlFor transmitting a set of symbols X ═ X1,…,xkThe l-th transmission symbol in (1) }, pY/X(Yi[m,l])＝xl|X[m,l]＝xkExpressed as the probability, p, of obtaining the ith symbol of the symbol set after demodulation by the ith cooperative receiver under the condition that the transmitter transmits the kth symbol of the mth block of the first channel-coded signaliIndicating the probability of error.
6. The method of claim 1, wherein the transmitting log-likelihood ratios of the remaining (Q-1) cooperative receivers to the fused receiver by way of air interface information fusion comprises:
multiplying the log-likelihood ratio of the (Q-1) cooperative receivers by a normalization factor b to obtain a normalized signal, and repeatedly sending the normalized signal to the fusion receiver for Z times, wherein Z is a set constant;
receiving the normalized signal by the fusion receiver through a normalization factor a to obtain a received signal, wherein the received signal is represented as:
Figure FDA0002743322540000026
wherein the content of the first and second substances,
Figure FDA0002743322540000027
means that the z-th received signal of the fusion receiver is the sum of log-likelihood ratios of the (Q-1) cooperative receivers with respect to the k-th transmitted symbol,
Figure FDA0002743322540000031
for the channel coefficient between the ith user and the converged receiver, nzWhite gaussian noise generated for the fused receiver,
Figure FDA0002743322540000032
indicating that the ith cooperative receiver is transmitting symbol xkLog-likelihood ratio of (1), normalization factor
Figure FDA0002743322540000033
And azReceiving signals according to Z times
Figure FDA0002743322540000034
Sum of the smallest received signal and the log-likelihood ratio values of the (Q-1) receivers for the k-th transmitted symbol
Figure FDA0002743322540000035
The mean square error of (a) is jointly designed.
7. The method of claim 6, wherein said controlling the fusion receiver to integrate log-likelihood ratio information of the Q cooperative receivers comprises:
controlling the fusion receiver to combine the received signals of Z times to obtain final log-likelihood ratio information, wherein the final log-likelihood ratio information is as follows:
Figure FDA0002743322540000036
the final log likelihood ratio information r is processedkLog-likeness to the fused receiverAir-fuel ratio
Figure FDA0002743322540000037
Adding to obtain an integrated set X { X } of transmission symbols1,…,xkLog-likelihood ratio information of the kth symbol in
Figure FDA0002743322540000038
8. The method of claim 1, wherein decoding the first channel-encoded signal according to the integrated log-likelihood ratio information to obtain a decoding result comprises:
determining a set of transmit symbols X ═ X1,…,xkThe maximum value of log likelihood ratio information after air interface fusion is carried out on each sending symbol in the symbol array;
determining a position number of the ith transmission symbol in the mth block signal corresponding to the first channel coding signal in the set X according to the maximum value of the log-likelihood ratio information; namely:
Figure FDA0002743322540000039
wherein k is*The position sequence number of the ith transmission symbol in the mth block signal of the first channel coding signal in the transmission set X is obtained;
determining, according to the position sequence number, that a decoding result obtained by the fusion receiver is:
Figure FDA00027433225400000310
wherein the content of the first and second substances,
Figure FDA00027433225400000311
denoted as kth in the set of transmitted symbols X*The transmission symbol of the position sequence number.
9. A cooperative receiving system based on air interface information fusion is characterized by comprising:
a transmitter for simultaneously transmitting first channel coded signals to N cooperative receivers, where N is a set constant;
the cooperative receiver is used for eliminating the phase rotation of the first channel coding signal by a channel to obtain a second channel coding signal;
the log-likelihood ratio calculation module is used for calculating the signal-to-noise ratio of the second channel coding signals of the N cooperative receivers, selecting Q cooperative receivers in a set signal-to-noise ratio range from the N cooperative receivers, and calculating the log-likelihood ratio according to the second channel coding signals of the Q cooperative receivers, wherein Q is a positive integer and Q is less than or equal to N;
an empty information fusion transmission module, configured to select one cooperative receiver from the Q cooperative receivers as a fusion receiver arbitrarily, and transmit the log-likelihood ratios of the remaining (Q-1) cooperative receivers to the fusion receiver in an empty information fusion manner;
the information integration module is used for controlling the fusion receiver to integrate the log-likelihood ratio information of the Q cooperative receivers;
the decoding module is used for decoding the first channel coding signal according to the integrated log-likelihood ratio information to obtain a decoding result;
a propagation module for broadcasting the decoding result to (N-1) cooperative receivers other than the fusion receiver.
10. The system according to claim 9, wherein the air interface information fusion transmission module includes:
a normalized information sending module, configured to repeatedly send a normalized signal obtained by multiplying the log-likelihood ratio of the (Q-1) cooperative receivers by a normalization factor b to the fusion receiver Z times, where Z is a set constant;
and the normalized information receiving module is used for receiving the normalized signal by the fusion receiver through a normalization factor a to obtain a received signal.
CN202011157897.0A 2020-07-21 2020-10-26 Cooperative receiving method and system based on air interface information fusion Pending CN112511270A (en)

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