CN103841065A - Non-orthogonal multi-user access and sending and combined receiving, demodulation and coding system and method - Google Patents

Abstract

The invention discloses a non-orthogonal multi-user access and sending and combined receiving, demodulation and coding system and method, and belongs to the technical field of communication. The method is characterized in that at a sending end, multiple users have access to the system in a non-orthogonal mode, and channel coding, coded symbol mapping, interleaving and modulation are carried out on a signal; at a receiving end, the received signal is multiplied by the feature sequence of each user, multi-user detection, demodulation, de-interleaving and decoding are sequentially carried out on the received signal, then multi-user detection is carried out on an output result again, and the iteration process is achieved. Based on the message passing conception, output soft information of a decoder is directly sent to undergo multi-user detection so as to achieve decoding and multi-user detection combined iteration processing. By means of the method, based on linear computation complexity, good interference elimination performance can be achieved, influence, caused by environmental noise and interference, on signal information is effectively reduced, and good BER performance and a more reliable transmission effect are achieved; meanwhile, multi-user interference elimination and decoding can be combined to be carried out, and therefore a parallel structure can be easily realized.

Description

Nonopiate multiple access sends and associating receiving demodulation decoding system and method

Technical field

Nonopiate multiple access transmission and associating receiving demodulation decoding system and method belong to communication technical field, particularly associating receiving demodulation decoding system and the method for a kind of nonopiate multiple access in multi-user comm and elimination inter-user interference.

Background technology

In order to reduce costs and utilize efficiently the resource of communication system, existing communication system generally adopts code division multiple access (Code Division Multiple Access, CDMA), interlacing multi-address (Interleaver Division Multiple Access, etc. IDMA) nonopiate access way is distinguished different users, along with the increase of number of users, inter-user interference can increase, thus the hydraulic performance decline of whole communication system.

A traditional methods of eliminating multiuser interference is to regard inter-user interference as additive noise, detects independently each user's information, and systematic function is seriously limited to interference.Another kind of method is Multiuser Detection, no longer will disturb and work as noise processed, but be regarded as the information with a fixed structure, specifically utilizes the correlation properties between address code, suppresses even to eliminate the impact that multiple access disturbs.

Whether linear according to algorithm, existing multiuser detection algorithm can be divided into Linear Multiuser Detection algorithm and Multi-User Detection algorithm.Linear Multiuser Detection algorithm is the output vector to traditional matched filter _ybe a linear operation L, the impact of disturbing to eliminate multiple access.This method relates to matrix inversion operation, and computation complexity is conventionally higher.The basic thought of Multi-User Detection algorithm is to disturb to eliminate, i.e. reconstruct subscriber signal after testing detects other users after it is eliminated from receive signal again.This method can cause the propagation of error, brings larger time delay.

The present invention proposes nonopiate multiple access transmission and associating receiving demodulation decoding system and method.The main thought of this algorithm is at transmitting terminal, multiple users adopt nonopiate mode connecting system, at receiving terminal, transmit thought based on message, soft the output of decoder information is directly sent in Multiuser Detection, realized the Joint iteration processing of decoding and Multiuser Detection.Under linear computation complexity, the present invention can realize good interference elimination performance.

Summary of the invention

The object of this invention is to provide nonopiate multiple access transmission and associating receiving demodulation decoding system and method.At transmitting terminal, multi-user adopts nonopiate mode to access, and at receiving terminal, adopts message passing mechanism, realizes the Joint iteration processing of decoding and Multiuser Detection.The present invention is applicable to the multi-user comm of nonopiate access, its objective is reduction inter-user interference, improves the performance of transmission.

Nonopiate multiple access sends and associating receiving demodulation decoding system, it is characterized in that, is divided into two large systems, and the one, the nonopiate access of multi-user and transmitting system, the one, the associating receiving demodulation decoding system of multiple user signals, wherein:

(1) the nonopiate access of multi-user and transmitting system, is provided with channel coding module, coded identification mapping block, interleaving block and modulation module, wherein:

Channel coding module: the information sequence bk to k user carries out chnnel coding, k=1,2 ..., K, output sequence c after chnnel coding _k, L is sequence c after coding _klength;

Coded identification mapping block: described sequence c _kin each symbol be mapped as respectively length and be the characteristic sequence p of N _k, N is more than or equal to 1 natural number, p _k={ z ₁, z ₂..., z _n, z _i∈ 1, and-1}, i=1,2 ..., N, i is the sequence number of characteristic parameter z, the number that N is characteristic parameter, the mapping ruler of symbol is according to 1 → p _k, 0 →-p _k, mapping postorder is classified r as _k;

Interleaving block: the described sequence r of input _kinterweave, obtain sequence v _k;

Modulation module: the described sequence v of input _kmodulate, obtain sequence u _k, send to receiving terminal;

(2) the associating receiving demodulation decoding system of multiple user signals, is provided with: multiuser detection module, demodulation interleaving block and decoding module:

First by k user's receiving sequence y _k(n) be multiplied by each user's characteristic sequence p by symbol _k, obtain k user's observer nodes the number that wherein K is user, k=1,2 ..., K, n is the time of reception of each symbol, n=1,2 ..., N', N'=NL, L is the sequence c after coding _klength, N is characteristic sequence p _klength, l=1,2 ..., L, will as the input of multiuser detection module, enter iterative process;

Multiuser detection module, detects according to following steps:

A initialization, sets: T is iterations, and t is this iterations, t=1, and 2 ..., T, i=1,2 ..., K, j=1,2 ..., K, the number that K is user, when initial, the symbol node x by i user at moment n _i(n) to j user's observer nodes

the message of transmitting

at x _i(n)=1 o'clock ${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]=1)$ For

at x _i(n)=-1 o'clock ${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]=-1)$ For

B calculates in the t time iterative process the symbol node x by i user _i(n) to j user's observer nodes

the message of transmitting

${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n\left]\right)=k^{\′}*\underset{p\∈[1,k]\∩p\≠i,p\≠j}{\mathrm{\Π}}{\mathrm{\μ}}_{{\tilde{y}}_p\left[n\right]\→x_i\left[n\right]}^{t-1}\left(x_i\right[n\left]\right),k^{\′}\∈\left(\mathrm{0,1}\right],$

represent to remove i and j user, the continued product of the message that all the other the 1st observer nodes to k user transmit to i user's symbol node,

C calculates respectively according to above formula

average

and variance

${\mathrm{mean}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t=\underset{{\mathrm{\α}}_i\∈\{-\mathrm{1,1}\}}{\mathrm{\Σ}}{\mathrm{\α}}_i{\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]={\mathrm{\α}}_i),$

${\mathrm{var}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t=\underset{{\mathrm{\α}}_i\∈\{-\mathrm{1,1}\}}{\mathrm{\Σ}}{{|{\mathrm{\α}}_i-{\mathrm{mean}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t|}^2\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]={\mathrm{\α}}_i).$

D calculates the observer nodes of j user in the t time iterative process to i user's symbol node

pass the average of message

and variance

${\mathrm{mean}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t={\tilde{y}}_j\left[n\right]-\underset{p\≠i}{\mathrm{\Σ}}{\tilde{h}}_{j,p}\left[n\right]{\mathrm{mean}}_{x_p\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t,$

${\mathrm{var}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t=\underset{p\≠i}{\mathrm{\Σ}}{\tilde{h}}_{j,p}\left[n\right]{\mathrm{var}}_{x_p\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t{\tilde{h}*}_{j,p}\left[n\right]+{\mathrm{\σ}}^2,$

Wherein

represent j user's observer nodes symbol node x with i user _i(n) equivalent channel gain between, σ ²represent the variance of white Gaussian noise,

E is based on above-mentioned average

and variance

adopt Gaussian approximation, calculate in the t time iterative process j user's observer nodes

to i user's symbol node x _i(n) message of transmitting

${\mathrm{\μ}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t\left(x_i\right[n\left]\right)=\exp (-\frac{{\left|{\tilde{h}}_{j,i}{x}_i\right[n]-\mathrm{mea}{n}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t|}^2}{{\mathrm{var}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t});$

Demodulation interleaving block: according to

calculate the symbol node x of i user in the t time iterative process _i(n) to the input node of decoder

the message of transmitting

${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{x}}_i\left[l\right]}\left(x_i\right[n\left]\right)=\underset{j}{\mathrm{\Π}}{\mathrm{\μ}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t\left(x_i\right[n\left]\right)$

Wherein, n=1,2 ..., N', N'=NL, l=1,2 ..., L,

According to above formula, further obtain the input message of decoder

${\mathrm{\μ}}_{{\tilde{x}}_i\left[l\right]\→\mathrm{dec}}^t\left({\tilde{x}}_i\right[l\left]\right)=\underset{n=1+(l-1)N}{\stackrel{N+(l-1)N}{\mathrm{\Π}}}{\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{x}}_i\left[l\right]}^t\left(x_i\right[n\left]\right);$

Decoding module: by the input node of described decoder

the form that is log-likelihood ratio to the message maps of decoder transmission, judgement obtains corresponding each user's information bit sequence

Repeat above-mentioned Multiuser Detection module to the step between decoding module until t=T.

Wherein:

Described nonopiate multiple access sends and associating receiving demodulation decoding system, and in channel coding module, coded system adopts such as convolution code, LDPC code, Turbo code, Turbo product code etc.

Described nonopiate multiple access sends and associating receiving demodulation decoding system, in modulation module, adopts Different Modulations such as quadrature amplitude modulation (QAM), quarternary phase-shift keying (QPSK) signal (QPSK), multi-system digital phase modulation (MPSK).

Described nonopiate multiple access sends and associating receiving demodulation decoding system, in interleaving block, adopts such as Block Interleaver, convolutional deinterleaver or random interleaver.

Nonopiate multiple access sends and associating receiving demodulation interpretation method, is divided into two large steps, and the one, the nonopiate access of multi-user and transmission, the one, the associating receiving demodulation decoding of multiple user signals:

(1) the nonopiate access of multi-user and forwarding step, specifically comprises chnnel coding, coded identification mapping, interweaves and modulate, and transmitting terminal operates by following concrete steps each user:

Chnnel coding: to k user's information sequence b _kcarry out chnnel coding, k=1,2 ..., K, output sequence c after chnnel coding _k, L is sequence c after coding _klength;

Coded identification mapping: described sequence c _kin each symbol be mapped as respectively length and be the characteristic sequence p of N _k, N is more than or equal to 1 natural number, p _k={ z ₁, z ₂..., z _n, z _i∈ 1, and-1}, i=1,2 ..., N, i is the sequence number of characteristic parameter z, the number that N is characteristic parameter, the mapping ruler of symbol is according to 1 → p _k, 0 →-p _k, mapping postorder is classified r as _k;

Interweave: the described sequence r of input _kinterweave, obtain sequence v _k;

Modulation: the described sequence v of input _kmodulate, obtain sequence u _k, send to receiving terminal;

(2) the associating receiving demodulation decoding procedure of multiple user signals, comprises that multiuser detection, demodulation interweave, decoding:

First by k user's receiving sequence y _k(n) be multiplied by each user's characteristic sequence p by symbol _k, obtain k user's observer nodes

the number that wherein K is user, k=1,2,3 ..., K, n is the time of reception of each symbol, n=1,2 ..., N', N'=NL, L is the sequence c after coding _klength, N is characteristic sequence p _klength, l=1,2 ..., L, will

as the input of multiuser detection module, enter iterative process;

Multiuser detection, according to following steps:

A initialization, sets: T is iterations, and t is this iterations, t=1, and 2 ..., T, i=1,2 ..., K, j=1,2 ..., K, the number that K is user, when initial, the symbol node x by i user at moment n _i(n) to j user's observer nodes

the message of transmitting

at x _i(n)=1 o'clock ${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]=1)$ For

at x _i(n)=-1 o'clock ${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]=1)$ For

B calculates in the t time iterative process the symbol node x by i user _i(n) to j user's observer nodes the message of transmitting

${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n\left]\right)=k^{\′}*\underset{p\∈[1,k]\∩p\≠i,p\≠j}{\mathrm{\Π}}{\mathrm{\μ}}_{{\tilde{y}}_p\left[n\right]\→x_i\left[n\right]}^{t-1}\left(x_i\right[n\left]\right),k^{\′}\∈\left(\mathrm{0,1}\right],$

represent to remove i and j user, the continued product of the message that all the other the 1st observer nodes to k user transmit to i user's symbol node,

C calculates respectively according to above formula

average

and variance

${\mathrm{mean}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t=\underset{{\mathrm{\α}}_i\∈\{-\mathrm{1,1}\}}{\mathrm{\Σ}}{\mathrm{\α}}_i{\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]={\mathrm{\α}}_i),$

${\mathrm{var}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t=\underset{{\mathrm{\α}}_i\∈\{-\mathrm{1,1}\}}{\mathrm{\Σ}}{{|{\mathrm{\α}}_i-{\mathrm{mean}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t|}^2\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]={\mathrm{\α}}_i).$

D calculates the observer nodes of j user in the t time iterative process

to i user's symbol node x _i(n) average of pass-along message

and variance

${\mathrm{mean}}_{{\tilde{y}}_j\left[n\right]\→x_j\left[n\right]}^t={\tilde{y}}_j\left[n\right]-\underset{p\≠i}{\mathrm{\Σ}}{\tilde{h}}_{j,p}\left[n\right]{\mathrm{mean}}_{x_p\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t,$

${\mathrm{var}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t=\underset{p\≠i}{\mathrm{\Σ}}{\tilde{h}}_{j,p}\left[n\right]{\mathrm{var}}_{x_p\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t{\tilde{h}*}_{j,p}\left[n\right]+{\mathrm{\σ}}^2,$

Wherein

represent j user's observer nodes

symbol node x with i user _i(n) equivalent channel gain between, σ ²represent the variance of white Gaussian noise,

E is based on above-mentioned average

and variance

adopt Gaussian approximation, calculate in the t time iterative process j user's observer nodes

to i user's symbol node x _i(n) message of transmitting

${\mathrm{\μ}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t\left(x_i\right[n\left]\right)=\exp (-\frac{{\left|{\tilde{h}}_{j,i}{x}_i\right[n]-\mathrm{mea}{n}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t|}^2}{{\mathrm{var}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t});$

Demodulation interweaves: according to

calculate the symbol node x of i user in the t time iterative process _i(n) to the input node of decoder the message of transmitting

${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{x}}_i\left[l\right]}^t\left(x_i\right[n\left]\right)=\underset{j}{\mathrm{\Π}}{\mathrm{\μ}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t\left(x_i\right[n\left]\right),$

Wherein, n=1,2 ..., N', N'=NL, l=1,2 ..., L,

According to above formula, further obtain the input message of decoder

${\mathrm{\μ}}_{{\tilde{x}}_i\left[l\right]\→\mathrm{dec}}^t\left({\tilde{x}}_i\right[l\left]\right)=\underset{n=1+(l-1)N}{\stackrel{N+(l-1)N}{\mathrm{\Π}}}{\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{x}}_i\left[l\right]}^t\left(x_i\right[n\left]\right);$

Decoding: by the input node of described decoder

the form that is log-likelihood ratio to the message maps of decoder transmission, judgement obtains corresponding each user's information bit sequence

Repeat above-mentioned Multiuser Detection step to decoding procedure, until t=T.

Described nonopiate multiple access sends and associating receiving demodulation interpretation method, and in chnnel coding step, coded system adopts such as convolution code, LDPC code, Turbo code, Turbo product code etc.

Described nonopiate multiple access sends and associating receiving demodulation interpretation method, in modulation step, adopts Different Modulations such as quadrature amplitude modulation (QAM), quarternary phase-shift keying (QPSK) signal (QPSK), multi-system digital phase modulation (MPSK).

Described nonopiate multiple access sends and associating receiving demodulation interpretation method, interweaves in step, adopts such as Block Interleaver, convolutional deinterleaver or random interleaver.

In the present invention, method is compared with traditional multi-user interference eliminating method and is had following two notable features:

(1) eliminating interference performance strengthens;

(2) computational complexity reduces;

Accompanying drawing explanation

Fig. 1 is the nonopiate access of multi-user of the present invention and transmission flow figure.

Fig. 2 is multi-user association receiving demodulation decoding flow chart of the present invention.

Fig. 3 is the simulation curve figure described in the specific embodiment of the invention.

embodiment

Below in conjunction with drawings and Examples, the present invention is described in further details.

The nonopiate multiple access that the present invention proposes sends and associating receiving demodulation decoding system and method, below provides workflow, is convenient to understand object of the present invention, feature and advantage.Mainly be divided into two large systems, the one, the nonopiate access of multi-user and transmission, the one, multi-user's associating receiving demodulation decoding.

(1) as shown in Figure 1, the nonopiate access of multi-user and transmitting system, be provided with channel coding module, coded identification mapping block, interleaving block and modulation module (each use is operation according to the following steps per family):

Channel coding module: to k user's information sequence b _kcarry out chnnel coding, k=1,2 ..., K, output sequence c after chnnel coding _k, L is sequence c after coding _klength;

Coded identification mapping block: described sequence c _kin each symbol be mapped as respectively length and be the characteristic sequence p of N _k, N is more than or equal to 1 natural number, p _k={ z ₁, z ₂..., z _n, z _i∈ 1, and-1}, i=1,2 ..., N, i is the sequence number of characteristic parameter z, the number that N is characteristic parameter, the mapping ruler of symbol is according to 1 → p _k, 0 →-p _k, mapping postorder is classified r as _k;

Interleaving block: the described sequence r of input _kinterweave, obtain sequence v _k;

Modulation module: the described sequence v of input _kmodulate, obtain sequence u _k, send to receiving terminal;

(2) the associating receiving demodulation decoding system of multiple user signals, is provided with: multiuser detection module, demodulation interleaving block and decoding module:

First by k user's receiving sequence y _k(n) be multiplied by each user's characteristic sequence p by symbol _k, obtain k user's observer nodes

the number that wherein K is user, k=1,2 ..., K, n is the time of reception of each symbol, n=1,2 ..., N', N'=NL, L is the sequence c after coding _klength, N is characteristic sequence p _klength, l=1,2 ..., L, will as the input of multiuser detection module, enter iterative process;

Multiuser detection module, detects according to following steps:

A initialization, sets: T is iterations, and t is this iterations, t=1, and 2 ..., T, i=1,2 ..., K, j=1,2 ..., K, the number that K is user, when initial, the symbol node x by i user at moment n _i(n) to j user's observer nodes

the message of transmitting

at xi (n)=1 o'clock ${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]=1)$ For

at x _i(n)=-1 o'clock ${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]=-1)$ For

B calculates in the t time iterative process the symbol node x by i user _i(n) to j user's observer nodes the message of transmitting

C calculates respectively according to above formula

average

and variance

D calculates the observer nodes of j user in the t time iterative process

to i user's symbol node x _i(n) average of pass-along message

and variance

E is based on above-mentioned average

and variance adopt Gaussian approximation, calculate in the t time iterative process j user's observer nodes to i user's symbol node x _i(n) message of transmitting

Demodulation interleaving block: according to calculate the symbol node x of i user in the t time iterative process _i(n) to the input node of decoder

the message of transmitting and the input message of decoder;

Decoding module: by the input node of described decoder

the form that is log-likelihood ratio to the message maps of decoder transmission, judgement obtains corresponding each user's information bit sequence

Repeat above-mentioned Multiuser Detection module to the step between decoding module until t=T.

A specific embodiment of the present invention

The nonopiate multiple access that the present invention proposes sends and associating receiving demodulation decoding system and method, take multi-user's cdma spread spectrum communication system as example, spreading ratio is N=16, system user number is K=6, supposes to adopt the LDPC coding of 1/2 code check, and code length is 1024, adopt perfect power control, BPSK modulation, random interleaving, channel is awgn channel.Below provide workflow, be convenient to understand object of the present invention, feature and advantage.

(1) the information bit sequence b to each user _kcarry out LDPC coding, the sequence c after being encoded _k;

(2) by the sequence c after coding _kdivide and be mapped as the sequence that length is N (N is more than or equal to 1 natural number)

P _k={ z ₁, z ₂..., z _n, (z _i∈ 1, and-1}, i=1,2 ..., N), obtain the sequence r after spread spectrum _k, mapping ruler is as follows: 1 → p _k, 0 →-p _k, complete spread spectrum;

(3) to the sequence r after spread spectrum _kcarry out random interleaving processing, obtain sequence v _k;

(4) to sequence v _kcarry out launching after BPSK modulation;

(5) radio frequency unit of terminal receives signal, realizes down-conversion and analog to digital conversion, produces digital baseband signal;

(6) receiving sequence y (n) is multiplied by each user's sequence p by symbol _k, obtain a corresponding K user's K road sequence

wherein k=1,2 ..., K, n=1,2 ..., NL, L is the sequence c after coding _klength.

(7) by K user's observer nodes

substitution Multiuser Detection node, according to

value, in conjunction with putting letter algorithm and central-limit theorem, calculate message described in the t time iterative process

and

${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n\left]\right);$

(8) basis

value, calculate x _i(n) to

the message of transmitting

(9) basis

calculate

the message of transmitting to decoder

(10) in decoder, by above-mentioned

the form that is log-likelihood ratio to the message maps of decoder transmission:

based on log-likelihood ratio, obtain corresponding each user's information bit sequence

(11) repeat said process (7)-(11), until meet iterations.

Said system is carried out to Computer Simulation test, has drawn result below:

Set following two groups of simulation parameters, as shown in table 1.

Table 1

Fig. 3 has represented the simulation curve in Case1 and two kinds of situations of Case2, compared with iteration MMSE algorithm in two kinds of situations, Joint iteration algorithm under identical iterations can effectively improve the performance of system, and along with the increase of iterations, the performance of Joint iteration algorithm approaches the performance of alone family when noiseless more.

Effect of the present invention is, by utilizing propagation and the renewal of external information on the factor graph of Multiuser Detection node formation to make external information feature more reliably, effectively lower ambient noise and disturb the impact on signal message, lower error code result and more reliable laser propagation effect are obtained, this algorithm can be realized multi-user interference elimination and carry out combining of decoding simultaneously, is conducive to the realization of parallel organization.Therefore, eliminate for multi-user interference, this method is obviously better than additive method.

Claims (12)

1. nonopiate multiple access sends and associating receiving demodulation decoding system, it is characterized in that, is divided into two large systems, and the one, the nonopiate access of multi-user and transmitting system, the one, the associating receiving demodulation decoding system of multiple user signals, wherein:

(1) the nonopiate access of multi-user and transmitting system, is provided with channel coding module, coded identification mapping block, interleaving block and modulation module, wherein:

Channel coding module: to k user's information sequence b _kcarry out chnnel coding, k=1,2 ..., K, output sequence c after chnnel coding _k, L is sequence c after coding _klength;

Coded identification mapping block: described sequence c _kin each symbol be mapped as respectively length and be the characteristic sequence p of N _k, N is more than or equal to 1 natural number, p _k={ z ₁, z ₂..., z _n, z _i∈ 1, and-1}, i=1,2 ..., N, i is the sequence number of characteristic parameter z, the number that N is characteristic parameter, the mapping ruler of symbol is according to 1 → p _k, 0 →-p _k, mapping postorder is classified r as _k;

Interleaving block: the described sequence r of input _kinterweave, obtain sequence v _k;

Modulation module: the described sequence v of input _kmodulate, obtain sequence u _k, send to receiving terminal;

(2) the associating receiving demodulation decoding system of multiple user signals, is provided with: multiuser detection module, demodulation interleaving block and decoding module:

First by k user's receiving sequence y _k(n) be multiplied by each user's characteristic sequence p by symbol _k, obtain k user's observer nodes

the number that wherein K is user, k=1,2 ..., K, n is the time of reception of each symbol, n=1,2 ..., N', N'=NL, L is the sequence c after coding _klength, N is characteristic sequence p _klength, l=1,2 ..., L, will

as the input of multiuser detection module, enter iterative process;

Multiuser detection module, detects according to following steps:

A initialization, sets: T is iterations, and t is this iterations, t=1, and 2 ..., T, i=1,2 ..., K, j=1,2 ..., K, the number that K is user, when initial, the symbol node x by i user at moment n _i(n) to j user's observer nodes

the message of transmitting

at x _i(n)=1 o'clock ${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]=1)$ For

, at x _i(n)=-1 o'clock ${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]=-1)$ For

B calculates in the t time iterative process the symbol node x by i user _i(n) to j user's observer nodes

the message of transmitting

${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n\left]\right)=k^{\′}*\underset{p\∈[1,k]\∩p\≠i,p\≠j}{\mathrm{\Π}}{\mathrm{\μ}}_{{\tilde{y}}_p\left[n\right]\→x_i\left[n\right]}^{t-1}\left(x_i\right[n\left]\right),k^{\′}\∈\left(\mathrm{0,1}\right],$

$\underset{p\∈[1,k]\∩p\≠i,p\≠j}{\mathrm{\Π}}{\mathrm{\μ}}_{{\tilde{y}}_p\left[n\right]\→x_i\left[n\right]}^{t-1}\left(x_i\right[n\left]\right)$ Represent to remove i and j user, the continued product of the message that all the other the 1st observer nodes to k user transmit to i user's symbol node,

C calculates respectively according to above formula

average

and variance

D calculates the observer nodes of j user in the t time iterative process to i user's symbol node x _i(n) average of pass-along message

and variance

E is based on above-mentioned average and variance

adopt Gaussian approximation, calculate in the t time iterative process j user's observer nodes

to i user's symbol node x _i(n) message of transmitting

${\mathrm{\μ}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t\left(x_i\right[n\left]\right)=\exp (-\frac{{\left|{\tilde{h}}_{j,i}{x}_i\right[n]-\mathrm{mea}{n}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t|}^2}{{\mathrm{var}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t});$

Demodulation interleaving block: according to

calculate the symbol node x of i user in the t time iterative process _i(n) to the input node of decoder the message of transmitting

${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_i\left[l\right]}^t\left(x_i\right[n\left]\right)=\underset{j}{\mathrm{\Π}}{\mathrm{\μ}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t\left(x_i\right[n\left]\right),$

Wherein, n=1,2 ..., N', N'=NL, l=1,2 ..., L,

According to above formula, further obtain the input message of decoder

${\mathrm{\μ}}_{{\tilde{x}}_i\left[l\right]\→\mathrm{dec}}^t\left({\tilde{x}}_i\right[l\left]\right)=\underset{n=1+(l-1)N}{\stackrel{N+(l-1)N}{\mathrm{\Π}}}{\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{x}}_i\left[l\right]}^t\left(x_i\right[n\left]\right);$

Decoding module: by the input node of described decoder the form that is log-likelihood ratio to the message maps of decoder transmission, judgement obtains corresponding each user's information bit sequence

Repeat above-mentioned Multiuser Detection module to the step between decoding module until t=T.

2. nonopiate multiple access according to claim 1 sends and associating receiving demodulation decoding system, it is characterized in that, in channel coding module, coded system adopts such as convolution code, LDPC code, Turbo code, Turbo product code etc.

3. nonopiate multiple access according to claim 1 sends and associating receiving demodulation decoding system, it is characterized in that, in modulation module, adopt Different Modulations such as quadrature amplitude modulation (QAM), quarternary phase-shift keying (QPSK) signal (QPSK), multi-system digital phase modulation (MPSK).

4. nonopiate multiple access according to claim 1 sends and associating receiving demodulation decoding system, it is characterized in that, in interleaving block, adopts such as Block Interleaver, convolutional deinterleaver or random interleaver.

5. nonopiate multiple access according to claim 1 sends and associating receiving demodulation decoding system, it is characterized in that, and in Multiuser Detection module,

average

and variance

be calculated as follows:

${\mathrm{mean}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t=\underset{{\mathrm{\α}}_i\∈\{-\mathrm{1,1}\}}{\mathrm{\Σ}}{\mathrm{\α}}_i{\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]={\mathrm{\α}}_i),$

${\mathrm{var}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t=\underset{{\mathrm{\α}}_i\∈\{-\mathrm{1,1}\}}{\mathrm{\Σ}}{{|{\mathrm{\α}}_i-{\mathrm{mean}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t|}^2\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]={\mathrm{\α}}_i).$

6. nonopiate multiple access according to claim 1 sends and associating receiving demodulation decoding system, it is characterized in that, and in Multiuser Detection module, j user's observer nodes

to i user's symbol node x _i(n) average of pass-along message

and variance

${\mathrm{mean}}_{{\tilde{y}}_j\left[n\right]\→x_j\left[n\right]}^t={\tilde{y}}_j\left[n\right]-\underset{p\≠i}{\mathrm{\Σ}}{\tilde{h}}_{j,p}\left[n\right]{\mathrm{mean}}_{x_p\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t,$

${\mathrm{var}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t=\underset{p\≠i}{\mathrm{\Σ}}{\tilde{h}}_{j,p}\left[n\right]{\mathrm{var}}_{x_p\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t{\tilde{h}*}_{j,p}\left[n\right]+{\mathrm{\σ}}^2,$

Wherein

represent j user's observer nodes

symbol node x with i user _i(n) equivalent channel gain between, σ ²represent the variance of white Gaussian noise.

7. nonopiate multiple access according to claim 1 sends and associating receiving demodulation decoding system, it is characterized in that, the nonopiate multiple access proposing sends and associating receiving demodulation interpretation method, be divided into two large steps, the one, the nonopiate access of multi-user and transmission, the one, the associating receiving demodulation decoding of multiple user signals:

(1) the nonopiate access of multi-user and forwarding step, specifically comprises chnnel coding, coded identification mapping, interweaves and modulate, and transmitting terminal operates by following concrete steps each user:

Chnnel coding: to k user's information sequence b _kcarry out chnnel coding, k=1,2 ..., K, output sequence c after chnnel coding _k, L is sequence c after coding _klength;

Coded identification mapping: described sequence c _kin each symbol be mapped as respectively length and be the characteristic sequence p of N _k, N is more than or equal to 1 natural number, p _k={ z ₁, z ₂..., z _n, z _i∈ 1, and-1}, i=1,2 ..., N, i is the sequence number of characteristic parameter z, the number that N is characteristic parameter, the mapping ruler of symbol is according to 1 → p _k, 0 →-p _k, mapping postorder is classified r as _k;

Interweave: the described sequence r of input _kinterweave, obtain sequence v _k;

Modulation: the described sequence v of input _kmodulate, obtain sequence u _k, send to receiving terminal;

(2) the associating receiving demodulation decoding procedure of multiple user signals, comprises that multiuser detection, demodulation interweave, decoding:

First by k user's receiving sequence y _k(n) be multiplied by each user's characteristic sequence p by symbol _k, obtain k user's observer nodes

the number that wherein K is user, k=1,2,3 ..., K, n is the time of reception of each symbol, n=1,2 ..., N', N'=NL, L is the sequence c after coding _klength, N is characteristic sequence p _klength, l=1,2 ..., L, will

as the input of multiuser detection module, enter iterative process;

Multiuser detection, according to following steps:

A initialization, sets: T is iterations, and t is this iterations, t=1, and 2 ..., T, i=1,2 ..., K, j=1,2 ..., K, the number that K is user, when initial, the symbol node x by i user at moment n _i(n) to j user's observer nodes

the message of transmitting

at x _i(n)=1 o'clock ${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]=1)$ For at x _i(n)=-1 o'clock ${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]=-1)$ For

B calculates in the t time iterative process the symbol node x by i user _i(n) to j user's observer nodes

the message of transmitting

${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n\left]\right)=k^{\′}*\underset{p\∈[1,k]\∩p\≠i,p\≠j}{\mathrm{\Π}}{\mathrm{\μ}}_{{\tilde{y}}_p\left[n\right]\→x_i\left[n\right]}^{t-1}\left(x_i\right[n\left]\right),k^{\′}\∈\left(\mathrm{0,1}\right],$

represent to remove i and j user, the continued product of the message that all the other the 1st observer nodes to k user transmit to i user's symbol node,

C calculates respectively according to above formula average

and variance

D calculates the observer nodes of j user in the t time iterative process

to i user's symbol node x _i(n) average of pass-along message and variance

E is based on above-mentioned average

and variance

adopt Gaussian approximation, calculate in the t time iterative process j user's observer nodes

to i user's symbol node x _i(n) message of transmitting

${\mathrm{\μ}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t\left(x_i\right[n\left]\right)=\exp (-\frac{{\left|{\tilde{h}}_{j,i}{x}_i\right[n]-\mathrm{mea}{n}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t|}^2}{{\mathrm{var}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t});$

Demodulation interweaves: according to

calculate the symbol node x of i user in the t time iterative process _i(n) to the input node of decoder

the message of transmitting

${\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{x}}_i\left[l\right]}^t\left(x_i\right[n\left]\right)=\underset{j}{\mathrm{\Π}}{\mathrm{\μ}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t\left(x_i\right[n\left]\right),$

Wherein, n=1,2 ..., N', N'=NL, l=1,2 ..., L,

According to above formula, further obtain the input message of decoder

${\mathrm{\μ}}_{{\tilde{x}}_i\left[l\right]\→\mathrm{dec}}^t\left({\tilde{x}}_i\right[l\left]\right)=\underset{n=1+(l-1)N}{\stackrel{N+(l-1)N}{\mathrm{\Π}}}{\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{x}}_i\left[l\right]}^t\left(x_i\right[n\left]\right);$

Decoding: by the input node of described decoder

the form that is log-likelihood ratio to the message maps of decoder transmission, judgement obtains corresponding each user's information bit sequence

Repeat above-mentioned Multiuser Detection step to decoding procedure, until t=T.

8. nonopiate multiple access according to claim 1 sends and associating receiving demodulation interpretation method, it is characterized in that, in chnnel coding step, coded system adopts such as convolution code, LDPC code, Turbo code, Turbo product code etc.

9. nonopiate multiple access according to claim 1 sends and associating receiving demodulation interpretation method, it is characterized in that, in modulation step, adopt Different Modulations such as quadrature amplitude modulation (QAM), quarternary phase-shift keying (QPSK) signal (QPSK), multi-system digital phase modulation (MPSK).

10. nonopiate multiple access according to claim 1 sends and associating receiving demodulation interpretation method, it is characterized in that, interweaves in step, adopts such as Block Interleaver, convolutional deinterleaver or random interleaver.

11. nonopiate multiple access according to claim 1 send and associating receiving demodulation interpretation method, it is characterized in that, and in Multiuser Detection step,

average

and variance

be calculated as follows:

${\mathrm{mean}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t=\underset{{\mathrm{\α}}_i\∈\{-\mathrm{1,1}\}}{\mathrm{\Σ}}{\mathrm{\α}}_i{\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]={\mathrm{\α}}_i),$

${\mathrm{var}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t=\underset{{\mathrm{\α}}_i\∈\{-\mathrm{1,1}\}}{\mathrm{\Σ}}{{|{\mathrm{\α}}_i-{\mathrm{mean}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t|}^2\mathrm{\μ}}_{x_i\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t\left(x_i\right[n]={\mathrm{\α}}_i).$

12. nonopiate multiple access according to claim 1 send and associating receiving demodulation interpretation method, it is characterized in that, and in Multiuser Detection step, j user's observer nodes to i user's symbol node x _i(n) average of pass-along message

and variance

${\mathrm{mean}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t={\tilde{y}}_j\left[n\right]-\underset{p\≠i}{\mathrm{\Σ}}{\tilde{h}}_{j,p}\left[n\right]{\mathrm{mean}}_{x_p\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t,$

${\mathrm{var}}_{{\tilde{y}}_j\left[n\right]\→x_i\left[n\right]}^t=\underset{p\≠i}{\mathrm{\Σ}}{\tilde{h}}_{j,p}\left[n\right]{\mathrm{var}}_{x_p\left[n\right]\→{\tilde{y}}_j\left[n\right]}^t{\tilde{h}*}_{j,p}\left[n\right]+{\mathrm{\σ}}^2,$

Wherein

represent j user's observer nodes

symbol node x with i user _i(n) equivalent channel gain between, σ ²represent the variance of white Gaussian noise.

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