CN103618585B - A joint multi-user detecting and decoding method based on a belief propagation algorithm - Google Patents
A joint multi-user detecting and decoding method based on a belief propagation algorithm Download PDFInfo
- Publication number
- CN103618585B CN103618585B CN201310516887.5A CN201310516887A CN103618585B CN 103618585 B CN103618585 B CN 103618585B CN 201310516887 A CN201310516887 A CN 201310516887A CN 103618585 B CN103618585 B CN 103618585B
- Authority
- CN
- China
- Prior art keywords
- tau
- external information
- user
- variance
- sigma
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Landscapes
- Error Detection And Correction (AREA)
Abstract
The invention relates to a joint multi-user detecting and decoding method based on a belief propagation algorithm and belongs to communication technical field, and in particular, relates to a joint multi-user detecting and decoding method for eliminating interference among multiple users based on a belief propagation algorithm in a multi-user communication system. The extrinsic information of bits and the extrinsic information of symbols of a user and are repeatedly iterated at encoding/decoding nodes and mapping/inverse mapping nodes. After the number of the iteration is satisfied, the joint multi-user detecting and decoding method may achieve joint interference elimination and decoding among multiple users. Compared with a conventional multi-user interference eliminating method, the joint multi-user detecting and decoding method is capable of effectively decreasing the computation complexity of an interference eliminating algorithm and increasing the performance of the interference elimination.
Description
Technical field
A communication technical field is belonged to, the associating Multiuser Detection disturbed between a kind of elimination multi-user based on belief propagation algorithm particularly in multi-user comm and interpretation method based on the associating Multiuser Detection of belief propagation algorithm and interpretation method.
Background technology
In order to reduce costs and utilize efficiently the resource of communication system, existing communication system allows multiple common-user system resource mostly.Generally can adopt time division multiple access (Time Division Multiple Access, TDMA), frequency division multiple access (Frequency Division Multiple Access, FDMA), the different modes such as code division multiple access (Code Division Multiple Access, CDMA) distinguish different users.These multi-access modes theoretic can fully distinguish each user, interference can not be produced between different user, but in practical communication system, ambient noise or synchronous error will cause there is interference between user, and inter-user interference can reduce the performance of system.
Inter-user interference is regarded as the additive noise in environment by conventional method, detects the information of each user independently.Along with the increase of number of users, inter-user interference can increase, and the performance of whole communication system can decline.Compared with conventional method, multiuser detection is no longer used as the interference of other users noise to process, but combine all users considering busy channel, weaken or eliminate the interference of other user to arbitrary user, detecting the information of certain user or all these users simultaneously.Traditional multi-user test method is divided into Linear Multiuser Detection method and Multi-User Detection method.Multiuser Detection linear algorithm adopts linear operator L to dock collection of letters breath and processes.The basic thought of Multi-User Detection algorithm reconstructs the subscriber signal detected, detects other users again after it being eliminated from Received signal strength.These two kinds of methods all can relate to matrix inversion operation in processing procedure, and computation complexity is higher; In addition, detection and decoding are separated independent process by traditional receiving handling method, namely first detect decoding again, cannot realize combined optimization.
The present invention proposes a kind of associating Multiuser Detection based on belief propagation algorithm and interpretation method.The present invention adopts belief propagation algorithm, utilize the structure of factor graph that symbol and intersymbol external information, the external information between symbol and bit and the external information between bit and bit are carried out iteration and renewal repeatedly, eliminate and decoding to obtain maximum a posteriori probability to carry out combining interference.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 a kind of associating Multiuser Detection based on belief propagation algorithm and interpretation method.The present invention uses belief propagation algorithm, by the external information of the bit of user and the external information of symbol at " coding/decoding node " with " mapping/anti-mapping node " iterates, after meeting iterations, the interference of combining that the present invention can realize between multi-user is eliminated and decoding.Compare with traditional multi-user interference eliminating method, the present invention effectively can reduce the computation complexity of interference cancellation algorithm and improve the performance of interference elimination.
A kind of associating Multiuser Detection based on belief propagation algorithm and interpretation method are characterised in that, described method detailed process realizes according to following steps successively:
Step (1), initialization:
I-th symbol sent first set in iteration detection method is x
i, x
iin average and the variance use of the t time iteration
with
represent, iterative algorithm initial phase t=1, arrange,
Meanwhile, adopt QPSK modulation owing to sending, one sends symbol and correspond to 2 coded-bits, in the t time iteration, and a kth coded-bit c of i-th transmission symbol
i,kexternal information be expressed as p
t(c
i,k) and this method to c
i,kc when being approximately Gaussian Profile
i,kexternal information be expressed as
be initialized as,
Step (2), propagate and upgrade external information:
In the iterations required, in the t time iterative process, N is total number of users, performs following steps:
Step (2.1), for numbering i, has 0 < i < N+1,
represent and send symbol node x
ibe delivered to observation symbol node f
jexternal information,
be
an approximate Gaussian Profile,
average and variance be expressed as
with
χ represents the symbol field of QPSK, performs following steps and upgrades
with
Step (2.2), based on upgrade after
with
for numbering j, there is 0 < j < N+1, h
i,jrepresent the coefficient of channel transfer matrix Η,
for the variance of noise, y
jfor a jth receiving symbol, upgrade
with
Meanwhile, for same j, for numbering i, there is 0 < i < N+1, will
be approximately a Gaussian Profile
after,
average
and variance
be respectively,
Step (2.3), for numbering i, has 0 < i < N+1, calculates x
iaverage in iteration MMSE detection algorithm
and variance
Meanwhile, for numbering q, there is 0 < q < Q+1, calculate coded-bit c
i,qexternal information
Step (3), utilizes
decoder completes an iterative process:
To l=1,2 ... L, q=1,2 ... Q, generates the coded-bit c of next iteration
i,qexternal information,
Step (4), repeats above step until meet iterations, exports decode results.
To compare with conventional multi-user interference elimination method based on the associating Multiuser Detection of belief propagation algorithm and interpretation method in the present invention and there are following two notable features:
● jointly eliminate interference;
● interference is eliminated and decoding Combined Treatment;
Respectively these two features are described below:
● jointly eliminate interference;
Based on different with traditional multiuser detection in the algorithm principle of Multiuser Detection part in associating Multiuser Detection and the interpretation method of belief propagation algorithm.Traditional Multi-User Detection method is the every iteration of serial interference elimination or parallel interference canceller is all once to eliminate and to rebuild, and can realize all users based on the associating Multiuser Detection of belief propagation algorithm and interpretation method and side by side jointly disturb elimination.
● interference is eliminated and decoding Combined Treatment;
As shown in Figure 2, the present invention contains " coding/decoding node ", " mapping/anti-mapping node " and " Multiuser Detection node ", feature due to this algorithm be external information in each node and each internodal propagation, three nodes closely link together the entire infrastructure of composition algorithm.The interference that the present invention realizes between different user at Multiuser Detection node is eliminated, and realizes decoding at coding and decoding node, namely achieves interference and eliminates and decoding Combined Treatment.
Accompanying drawing explanation
The associating Multiuser Detection of Fig. 1 based on belief propagation algorithm and the factor graph of interpretation method composition;
Fig. 2 is based on the associating Multiuser Detection of belief propagation algorithm and interpretation method algorithm flow chart;
Fig. 3 is based on the associating Multiuser Detection of belief propagation algorithm and interpretation method receiver schematic diagram;
Fig. 4 is based on the associating Multiuser Detection of belief propagation algorithm and interpretation method and the Performance comparision of MMSE decoding algorithm under RICE channel;
Embodiment
As shown in Figure 2, the associating Multiuser Detection that the present invention proposes and interpretation method comprise the following steps for the associating Multiuser Detection based on belief propagation algorithm that the present invention proposes and interpretation method:
When this method starts, the external information of first initialization top " coding/decoding node " as shown in Figure 2, the corresponding relation of information bit and coded-bit depends on coded system.The symbol sebolic addressing received is input to " the Multiuser Detection node " shown in accompanying drawing 1, and initialization associating Multiuser Detection and code translator, now arrange iterations and be initialized as 0.Then, do not meet iterations condition is set time, Multiuser Detection node carries out the special delivery of external information, calculating and renewal based on belief propagation algorithm; After meeting iterations, as shown in Figure 2, " Multiuser Detection node " exports the external information of the coded-bit obtained, and through " mapping/anti-mapping node ", " coding/decoding node " obtains decode results.
Principle and the arthmetic statement of the method for the invention are as follows:
1) initialization:
Iterative algorithm initial phase t=1, is arranged,
2) propagate and upgrade external information:
In the t time iterative process, perform following steps:
A) for numbering i, perform following steps and upgrade
with
B) based on upgrade after
with
for numbering j, there is 0 < j < N+1, upgrade
with
Meanwhile, for same j, for numbering i, there is 0 < i < N+1, upgrade
and variance
C) for numbering i, there is 0 < i < N+1, calculate
and variance
Meanwhile, for numbering q, there is 0 < q < Q+1, calculate coded-bit c
i,qexternal information
3) utilize
complete decode procedure:
To l=1,2 ... L, q=1,2 ... Q, generates the coded-bit c of next iteration
i,qexternal information,
4) repeat above step until meet iterations, export decode results.
A specific embodiment of the present invention
A kind of associating Multiuser Detection based on belief propagation algorithm that the present invention proposes and interpretation method, for multi-user's cdma spread spectrum communication system.The reverse link of this multi-user cdma spread spectrum communication system uses L frequency range, and the length of the spreading code that cdma spread spectrum communication system uses is 16, and Installed System Memory is 8 users, and modulation system is QPSK, and coding uses LDPC code, under RICE channel, and K=10.Below provide workflow, be convenient to understand object of the present invention, feature and advantage.
(1) LDPC code is adopted to encode to the information bit of each user;
(2), after each subscriber-coded bit stream carries out QPSK constellation point, complex data flow is formed.
(3) output time-domain data flow after complex data flow parallel-serial conversion;
(4) data that Base-Band Processing is later, through digital-to-analogue (D/A) conversion, form continuous analog signal, then through up-conversion, are modulated to radio frequency;
(5) finally modulation signal is launched.
(6) the radio frequency unit Received signal strength of terminal, realizes down-conversion and analog to digital conversion, produces digital baseband signal;
(7) external information calculated by the digital baseband information of multiple user substitutes into Multiuser Detection node, is transmitted and upgrades, draw the external information of multiple user symbol by belief propagation algorithm;
(8) external information of updated different user symbol is passed through " mapping/anti-mapping node ", calculate the external information of each subscriber-coded bit stream;
(9) external information of updated different user coded-bit is passed through " coding/decoding node ", calculate the external information of each user profile bit stream;
(10) by the external information of message bit stream that obtained according to the direction going down of schematic structure, successively pass through " coding/decoding node ", " coding/decoding node " and " Multiuser Detection node ", recalculates and upgrades external information;
(11) said process is repeated, until meet iterations.
Computer Simulation test is carried out to said system, the result below having drawn:
Accompanying drawing 4 and table 1, compare based on the associating Multiuser Detection of belief propagation algorithm and interpretation method and traditional MMSE ber curve.Can see that the associating Multiuser Detection based on belief propagation algorithm has the lower error rate with interpretation method under equal signal to noise ratio condition compared with additive method.
The performance of table 1. two kinds of decoding algorithms under RICE channel
? | E b/N 0=2dB | E b/N 0=3dB | E b/N 0=4dB |
IteraMMSE-QPSK | 0.0350 | 0.00038 | 0.0005 |
ABP-QPSK | 0.0175 | 0.0011 | 0.0001 |
Visible, adopt this method can obtain the lower error rate under identical signal to noise ratio condition, improve laser propagation effect.
Effect of the present invention is, propagation on the factor graph formed at Multiuser Detection node by utilizing external information and renewal make external information feature more reliably, effectively lower ambient noise and the impact of interference on signal message, obtain lower error code result and more reliable laser propagation effect, this algorithm can realize 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 (1)
1. the associating Multiuser Detection based on belief propagation algorithm and interpretation method are characterised in that, described method detailed process realizes according to following steps successively:
Step (1), initialization:
I-th symbol sent first set in iteration detection method is x
i, x
iin average and the variance use of the t time iteration
with
represent, iterative algorithm initial phase t=1, arrange,
Meanwhile, adopt QPSK modulation owing to sending, one sends symbol and correspond to 2 coded-bits, in the t time iteration, and a kth coded-bit c of i-th transmission symbol
i,kexternal information be expressed as p
t(c
i,k) and this method to c
i,kc when being approximately Gaussian Profile
i,kexternal information be expressed as
be initialized as,
Step (2), propagate and upgrade external information:
In the iterations required, in the t time iterative process, N is total number of users, performs following steps:
Step (2.1), for numbering i, has 0<i<N+1,
represent and send symbol node x
ibe delivered to the external information of observation symbol node fj,
be
an approximate Gaussian Profile,
average and variance be expressed as
with
χ represents the symbol field of QPSK, performs following steps and upgrades
with
Step (2.2), based on upgrade after
with
for numbering j, there is 0<j<N+1, h
i,jrepresent the coefficient of channel transfer matrix Η,
for the variance of noise, y
jfor a jth receiving symbol, upgrade variance
and average
Meanwhile, for same j, for numbering i, there is 0<i<N+1, will
be approximately a Gaussian Profile
after,
average
and variance
be respectively,
Step (2.3), for numbering i, has 0<i<N+1, calculates x
iaverage in iteration MMSE detection algorithm
and variance
Meanwhile, for numbering q, there is 0<q<Q+1, calculate coded-bit c
i,qexternal information
Wherein,
for about variable x
iaverage be
variance is
gauss of distribution function.
Step (3), utilizes
decoder completes an iterative process:
To l=1,2 ... L, q=1,2 ... Q, generates the coded-bit c of next iteration
i,qexternal information,
Step (4), repeats above step until meet iterations, exports decode results.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201310516887.5A CN103618585B (en) | 2013-10-28 | 2013-10-28 | A joint multi-user detecting and decoding method based on a belief propagation algorithm |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201310516887.5A CN103618585B (en) | 2013-10-28 | 2013-10-28 | A joint multi-user detecting and decoding method based on a belief propagation algorithm |
Publications (2)
Publication Number | Publication Date |
---|---|
CN103618585A CN103618585A (en) | 2014-03-05 |
CN103618585B true CN103618585B (en) | 2014-12-31 |
Family
ID=50169289
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CN201310516887.5A Active CN103618585B (en) | 2013-10-28 | 2013-10-28 | A joint multi-user detecting and decoding method based on a belief propagation algorithm |
Country Status (1)
Country | Link |
---|---|
CN (1) | CN103618585B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN105846962B (en) * | 2016-05-19 | 2018-08-28 | 清华大学 | A kind of combined channel state-detection and decoding algorithm based on classification learning |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN105846955B (en) * | 2016-03-17 | 2019-03-19 | 东南大学 | Multi-beam mobile satellite communication system multi-user association iterative detection decoding method |
CN105978662B (en) * | 2016-05-09 | 2018-04-10 | 清华大学 | A kind of Multiuser Detection interpretation method of array antenna satellite communication system |
CN106301517B (en) * | 2016-08-10 | 2018-07-06 | 清华大学 | Based on the satellite multi-beam joint-detection and interpretation method it is expected to propagate and system |
CN106571891A (en) * | 2016-10-24 | 2017-04-19 | 南京航空航天大学 | Fountain multiple access method |
CN106789798B (en) * | 2016-11-22 | 2020-04-17 | 北京邮电大学 | Data sending and receiving method and device based on space coupling data transmission technology |
CN106603083B (en) * | 2016-12-13 | 2020-01-24 | 南京信息工程大学 | Improved method based on LDPC code node residual degree belief propagation decoding |
CN106603201B (en) * | 2016-12-27 | 2018-05-29 | 清华大学 | A kind of multi-user combined detection method based on sampled point processing |
CN107241167B (en) * | 2017-06-29 | 2020-02-18 | 东南大学 | Improved method based on large-scale MIMO system BP detection |
CN107809299B (en) * | 2017-10-23 | 2019-04-16 | 哈尔滨工业大学 | After the first string of multiple users share access technology uplink and multi-user test method |
CN108282200B (en) * | 2018-03-07 | 2020-09-04 | 江南大学 | Factor graph-based confidence propagation signal detection method in large-scale MIMO system |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN1437345A (en) * | 2003-03-21 | 2003-08-20 | 清华大学 | Space-time iterative multiuser detecting algorithm based on soft sensitive bit and space grouping |
WO2006003607A2 (en) * | 2004-06-30 | 2006-01-12 | Koninklijke Philips Electronics, N.V. | System and method for maximum likelihood decoding in mimo wireless communication systems |
CN101237434A (en) * | 2008-03-10 | 2008-08-06 | 电子科技大学 | A soft judgement method for Graham M-PSK modulation |
-
2013
- 2013-10-28 CN CN201310516887.5A patent/CN103618585B/en active Active
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN1437345A (en) * | 2003-03-21 | 2003-08-20 | 清华大学 | Space-time iterative multiuser detecting algorithm based on soft sensitive bit and space grouping |
WO2006003607A2 (en) * | 2004-06-30 | 2006-01-12 | Koninklijke Philips Electronics, N.V. | System and method for maximum likelihood decoding in mimo wireless communication systems |
CN101237434A (en) * | 2008-03-10 | 2008-08-06 | 电子科技大学 | A soft judgement method for Graham M-PSK modulation |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN105846962B (en) * | 2016-05-19 | 2018-08-28 | 清华大学 | A kind of combined channel state-detection and decoding algorithm based on classification learning |
Also Published As
Publication number | Publication date |
---|---|
CN103618585A (en) | 2014-03-05 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CN103618585B (en) | A joint multi-user detecting and decoding method based on a belief propagation algorithm | |
CN103841065B (en) | Nonopiate multiple access is sent and joint receives demodulation coding system and method | |
CN101425871B (en) | Multi-element error correcting code transmitting and receiving apparatus, data communication system and related method | |
CN101026434A (en) | Low-complexity iterative detection decoding method and device | |
CN100373840C (en) | Method and apparatus for detecting normalized iterative soft interference cancelling signal | |
CN105554865A (en) | MIMO-SCMA system downlink design method based on STBC | |
CN107196737B (en) | SCMA decoding method based on message passing algorithm | |
CN106301517A (en) | The satellite multi-beam joint-detection propagated based on expectation and interpretation method and system | |
CN106936532A (en) | A kind of power domain non-orthogonal multiple accesses interpretation method | |
CN104009822B (en) | Based on new demodulation modification method of the imperfect channel estimation containing arrowband interference | |
Han et al. | A high performance joint detection and decoding scheme for LDPC coded SCMA system | |
Meng et al. | Expectation propagation based iterative multi-user detection for MIMO-IDMA systems | |
Wang et al. | Edge selection-based low complexity detection scheme for SCMA system | |
CN103580721B (en) | Multi-antenna iteration multi-user detection and device in a kind of complicated time-variant multipath channel | |
CN115514453A (en) | Trellis code multiple access system and transceiver processing method | |
CN101136896A (en) | Frequency domain iteration equalizing method based on fast Fourier transformation | |
CN100514948C (en) | Method for counteracting minimum mean-square error soft interference, signal detector and receiver | |
CN106992843A (en) | A kind of digital fountain code degree distribution optimization method based on access channel | |
CN104135347B (en) | Dirty paper coding and decoding method based on joint lattice forming technology in cognitive network | |
CN108880758A (en) | The iterative receiver algorithm for design of difference chaotic bit weaving code modulation system | |
CN103346863B (en) | A kind of arithmetic domain Bit Interleaved Coded Modulation method | |
CN103124251A (en) | Method and device of lowering PAPR (peak to average power ratio) of 60 GHz communication system based on LDPC (low density parity check) coding mechanism | |
Telagam et al. | Ber analysis of concatenated levels of encoding in GFDM system using labview | |
CN104767537A (en) | Turbo decoding method for OFDM power line communication system | |
CN103188003B (en) | Based on method for low complexity parallel interference cancellation and the system of iterative detection |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PB01 | Publication | ||
PB01 | Publication | ||
C10 | Entry into substantive examination | ||
SE01 | Entry into force of request for substantive examination | ||
C14 | Grant of patent or utility model | ||
GR01 | Patent grant |