CN101854229A - Iteration demodulation decoding method of encoded modulation signals based on climax frequency deviation compensation - Google Patents

Iteration demodulation decoding method of encoded modulation signals based on climax frequency deviation compensation Download PDF

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CN101854229A
CN101854229A CN 201010173679 CN201010173679A CN101854229A CN 101854229 A CN101854229 A CN 101854229A CN 201010173679 CN201010173679 CN 201010173679 CN 201010173679 A CN201010173679 A CN 201010173679A CN 101854229 A CN101854229 A CN 101854229A
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吴晓富
宋越
赵春明
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PLA University of Science and Technology
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Abstract

The invention relates to an iteration demodulation decoding method of encoded modulation signals based on climax frequency deviation compensation, effectively solving the problem of iteration demodulation decoding of an LDPC (Low Density Parity Check Codes) encoded BPSK (Binary Phase Shift Keying) modulation system under frequency deviation and an unknown-phase channel. The method comprises the following steps of: receiving one frame of a full frame of encoded modulation signals, and dividing the full frame into a plurality of signal subblocks; initializing the external information of encoded bits; carrying out frequency deviation estimation by adopting a revised M&M arithmetic according to the external information of the encoded bits and the sample value of the received one-frame signals; carrying out a Tikhonov demodulation arithmetic to complete signal demodulation according to the structure of the signal subblocks and the frequency deviation estimation, and outputting a demodulation soft value of the encoded bits; receiving the demodulation soft value by a decoder, completing decoding once according to a confidence coefficient transmission decoding arithmetic, and outputting the external information of the encoded bits; and outputting a decoded value when the iteration demodulation times reach the preset times, and otherwise, increasing the length of the signal subblocks and repeating the operation until decoding is successful or iteration times achieve the regulated value.

Description

Modulation signals advances the iterative demodulation coding/decoding method of compensate of frequency deviation based on layer
Technical field
The present invention relates to wireless and technical field of satellite communication, relate in particular to the iterative demodulation coding/decoding method and the device of modulation signals under a kind of utmost point low signal-to-noise ratio.
Background technology
In the wireless and satellite communication system, transmitted bit is subjected to the influence of channel random noise and produces random error.Theory and practice proves that providing the error correction/encoding method of transmission reliability by the introducing redundancy is the effective means of a class.And one of Turbo code of introducing in recent years and LDPC sign indicating number encoding scheme that to be the error correcting capability found so far the strongest.
Turbo code equals proposition [C.Berrou in 1993 by C.Berrou, A.Glavieux, andP.Thitimajshima, " Near Shannon limit error-correcting coding and decoding:Turbo-codes, " in ICC ' 93, Geneva, Swithzerland, May, 1993, pp.1064-1070], it is considered to one of maximum progress that coding theory in recent years obtains.Turbo code is 10 in the error rate under white Gaussian noise (Additive White GaussianNoise-AWGN) channel -5The time approach the channel capacity limit with the signal to noise ratio of 0.7dB.LDPC (Low-Density Parity Check) sign indicating number was at first proposed in 1961 by Gallager, was rediscovered by Mackay etc. but forgotten until 1996 by people for a long time.Well-designed LDPC long code performance even be better than Turbo code.For satellite channel, because power limited, the work signal to noise ratio that reduces satellite communication system is vital beyond doubt, introduces the shortcoming that Turbo (or LDPC) encoding and decoding technique can solve the satellite channel power limited well.
Relevant knowledge about the LDPC encoding and decoding sees [T.J.Richardson and R ü diger L.Urbanke for details, " TheCapacity of Low-Density Parity-Check Codes Under Message-Passing Decoding; " IEEE Trans.Inform.Theory, vol.47, Feb.2001, pp.599-618], the LDPC decoding adopts confidence level to relay decoding algorithm, carry out iterative decoding based on the bipartite graph structure, and output class is similar to the external information of Turbo decoding.
Than Turbo code, the design of LDPC sign indicating number more flexible (different code check/code length), the full parallel organization of LDPC sign indicating number decoding algorithm makes that the LDPC decoder of design high-throughput is easier.Therefore, the LDPC sign indicating number is mostly selected in the standardization of relevant chnnel coding for use in the future communications system.
According to 1 distribution character in the check matrix, the LDPC sign indicating number can be divided into regular LDPC sign indicating number and irregular LDPC codes.(the d of a rule v, d c)-LDPC sign indicating number means that check matrix has following characteristic: it is constant that each row contains 1 number, and its number is d cIt is also constant that each row contains 1 number, and its number is d vOtherwise, then be irregular LDPC codes.
Present most of Turbo/LDPC coding/decoding method has only been considered white Gaussian noise (AWGN) channel, and this is not enough in actual wireless and satellite communication.Under actual channel, after generally need modulating, coded digital signal sends again, and this just requires transmitting-receiving two-end that identical frequency generator is arranged.But because the non-ideal characteristic of practical devices, particularly transmission medium the time become characteristic such as decline, the frequency deviation and the phase place of the modulation signal of feasible transmitting-receiving are unknown in fact to a great extent, and this just requires receiver to carry out channel estimating and follows the tracks of to eliminate unknown frequency deviation and phase place to sending the influence of signal.Like this, thus the Turbo/LDPC sign indicating number is decoded is the research focus that paid close attention to by people to various parameters how to estimate Unknown Channel.The difficulty of this problem is: the signal to noise ratio of Turbo/LDPC sign indicating number work will be well below the signal to noise ratio under the normal condition, and in fact how accurately to estimate and to follow the tracks of channel parameter itself to be exactly a great problem under low signal-to-noise ratio.
In satellite and radio communication, typical channel unknown parameter is frequency shift (FS) (frequency deviation) and carrier phase.Traditional channel estimation technique is to adopt PHASE-LOCKED LOOP PLL TECHNIQUE.Because utmost point low signal-to-noise ratio is the particularity of communication down, traditional algorithm does not re-use.Possible solution is a channel estimating and channel decoding characteristic and replace the decoding of associating iterative demodulation independently separately before abandoning, and makes channel estimating that the redundancy of encoding and providing can be provided.
Summary of the invention
Technical problem: the purpose of this invention is to provide a kind of simple and practical iterative demodulation coding/decoding method of LDPC coding BPSK communication system under the utmost point low signal-to-noise ratio that is used for.
Technical scheme: modulation signals of the present invention advances the iterative demodulation coding/decoding method of compensate of frequency deviation based on layer, and its step comprises:
1) receives a frame modulation signals whole frame, and be cut to a plurality of signal subspace pieces;
2) external information of initialization codes bit;
3) according to the external information of coded-bit and a frame signal sample value that receives, adopt a kind of correction M﹠amp; The M algorithm carries out frequency offset estimating;
4) finish the signal demodulation, the soft value of the demodulation of output encoder bit according to the sub-block structure of current demand signal and a kind of correction Tikhonov demodulating algorithm of above-mentioned frequency offset estimating execution;
Decoder receives the above-mentioned soft value of demodulation, finishes once decoding according to the degree of confidence propagation decoding algorithm, and the external information of output encoder bit;
5) when the iterative demodulation number of times reaches predetermined times, the output decoder value, otherwise the length of increase signal subspace piece changes the next iteration demodulation over to, also is repeating step 3)-5).
Described 3) in based on a kind of correction M﹠amp; M algorithm computation frequency deviation can be passed through M﹠amp; M algorithm [M.Morelliand U.Mengali, " Feedforward frequency estimation for psk:A tutorial review; " Eur.Trans.Commun.Related Technol., vol.9, Mar./Apr.2004, pp.103-116] carry out correction measure of the present invention and carry out.
Described 4) signal encoded and that modulate that receives is carried out the soft value of demodulation that a kind of Tikhonov of correction demodulating algorithm is finished signal demodulation and output encoder bit, can pass through Tikhonov algorithm [G.Colavolpe, A.Barbieri, and G.Caire, " Algorithms for iterative decoding in the presence of strongphase noise; " IEEE J.Select.Areas Commun., vol.23, Sept.2005, pp.1748-1757] carry out correction measure of the present invention and carry out.。
The described LDPC sign indicating number that is encoded to also extends to the TURBO sign indicating number; The described BPSK of being modulated to also extends to the MPSK modulation.
The invention provides the iterative demodulation decoding algorithm of the unknown LDPC coding down of channel parameter (channel phase, inherent spurious frequency deviation) BPSK modulation.Based on the Tikhonov algorithm in conjunction with the distinctive correction of a kind of this patent M﹠amp; M frequency offset estimating algorithm has proposed the piecemeal startup, block size recovers and demodulating algorithm with the carrier wave that iteration constantly increases, and this algorithm can make full use of the iteration external information and finish the recovery of carrier wave frequency deviation and phase place and obtaining of demodulating data.If the carrier wave that utilizes this patent to propose recovers to carry out to received signal demodulation (" demodulation " speech in fact is the meaning of parameter correction) here, then the signal after the demodulation can be regarded desirable awgn channel as, thereby can adopt the standard degree of confidence propagation iterative decoding algorithm under the awgn channel effectively to decode.
The model of communication system that the present invention relates to is as follows: message bit stream is earlier through the LDPC encoder, and modulation sends on the channel coded-bit through BPSK again.Suppose channel phase, channel magnitude, noise variance, inherent spurious frequency deviation the unknown, under the bit synchronous hypothesis of ideal, the equivalent low pass complex signal that receives can be expressed as
r k = c k e j θ k + w k , k = 0 , . . . , N s - 1 ,
Wherein, c kThe bpsk signal that expression sends, its value in set of signals+1 ,-1}, θ kBe the channel unknown phase,
w kThe expression average is that 0 variance is 2 σ 2White complex gaussian noise, N sIt is the total length of a frame.
Symbol definition:
Iterations: l;
Coding code length in one frame: L;
The block count that coding codeword begins in iteration, size (below be called initial sub-piece): B, D and L=BD;
Lead sign indicating number and be distributed in each initial sub-piece, lead yardage: P in each sub-piece;
Block count, the size of the coding codeword data of the l time iteration: B l, D l
The piecemeal symbol size of the l time iteration (comprise coded identification and lead sign indicating number): N l
Frame signal total sample number a: N who receives s=(D+P) B;
Frame signal sample subscript a: k who receives;
Lead the subscript position set at yard place: I in the frame signal that receives p
The subscript position at coded data place set: I in the frame signal that receives d
A frame signal sample that receives:
Figure GSA00000122954000041
Revise M﹠amp; Segmentation accumulation length in the M frequency offset estimating algorithm: F;
One frame data are carried out sample length after segmentation adds up: N f=N s/ F.
The present invention relates to the summary of the invention of following four aspects:
One, layer advances the formula partition strategy
The layer of coded modulation small-signal of the present invention advances compensate of frequency deviation and demodulation method, its step 2) and 7) need advance the formula partition strategy according to iteration enforcement layer, the core that layer advances the formula partition strategy is branch block size N lConstantly enlarge (correspondingly, piecemeal number B with iteration lThen constantly reduce), initially piecemeal is less can guarantee that then the cumulative effect of frequency deviation in this little piecemeal is not obvious, thereby can start normally carrying out of demodulation.Thereby layer advances the formula partition strategy and will guarantee: N L+1〉=N lPerhaps B L+1≤ B lUp to the piecemeal number is 1.This layer advances the formula partition strategy can be referring to Fig. 1.
Two, revise M﹠amp; The M algorithm
Revise M﹠amp; The M algorithm flow (is designated as
Figure GSA00000122954000042
)
Step 1) is to a frame signal
Figure GSA00000122954000043
A yard information (k ∈ I is led in utilization p) and external information go modulation operations:
x k = r k · tanh ( L d ( c k ) ) , k ∈ I d ; r k · c k , k ∈ I p .
Step 2) based on the signal that goes to modulate
Figure GSA00000122954000051
Carrying out segmentation adds up and obtains N f=N s/ F sample z k, k=0 ..., N f-1:
z k = Σ j = 0 F - 1 x kF + j , k = 0 , . . . , N f - 1 .
Step 3) is based on the segmentation sample z that adds up k, k=0 ..., N f-1 calculates its autocorrelation value:
R s ( m ) = Σ k = 0 N f - 1 - m z k + m z k * , m = 0 , . . . , E .
Step 4) calculates final frequency offset estimating value according to following weighting scheme
Figure GSA00000122954000054
Wherein: w m = 3 ( ( 2 E + 1 ) 2 - ( 2 m + 1 ) 2 ) ( ( 2 E + 1 ) 2 - 1 ) ( 2 E + 1 ) ,
Δ(m)＝mod[arg(R(m+1))-arg(R(m))，2π].
Here mod[x, 2 π] expression is to x delivery 2 π.
Three, revise the Tikhonov algorithm
If the signal subspace piece is whole signal frame (r k, k=0 ..., N s-1) and known frequency offsets be estimated as
Figure GSA00000122954000056
In, then revise the Tikhonov algorithm has mainly been considered frequency deviation on the basis of Tikhnov algorithm phase place rotation effect, its concrete calculation process is as follows:
The step 1) front and back are to measuring iteration initialization:
a f , 0 = 0 , a b , N s - 1 = 0 .
Step 2) forward metrics iterative computation:
K-1 constantly declares α based on the symbol of external information is soft K-1=tanh (L (c K-1)) and variance β K-1=1,
K forward metrics constantly calculates
Figure GSA00000122954000058
After the step 3) to tolerance iterative computation:
Figure GSA00000122954000059
Step 4) demodulation bit soft value calculates:
Figure GSA00000122954000061
Perhaps adopt approximate calculation
y k = | a f , k + a b , k + r k · ( + 1 ) σ 2 | - | a f , k + a b , k + r k · ( - 1 ) σ 2 | , if , k ∈ I d
I wherein 0(x) expression zeroth order Bei Sheer function, for the purpose of simplifying calculating, we adopt approximate representation logI 0(x)=and x, can get approximate calculation, simplified calculating greatly.
Four, modulation signals advances the iterative demodulation coding/decoding method of compensate of frequency deviation based on layer
Step 1) parameter initialization: L (c kThe ∞ of)=+, k ∈ I pL (c k)=0, k ∈ I d, l=0.
Step 2) degree of confidence propagation decoding algorithm initialization;
Step 3) is carried out and is revised M﹠amp; M algorithm computation frequency deviation:
Figure GSA00000122954000063
Step 4) is carried out based on the Tikhonov algorithm of signal subspace piece and is finished carrier wave recovery and demodulation:
1) to g (g=0 ..., B l-1) before and after the height piece carrier wave to iteration initialization:
a f , 0 g = 0 , a b , N l - 1 g = 0 .
2) in g sub-piece, carry out carrier wave recover before and after to iterative computation:
The forward direction iterative computation:
k＝g(N l-P)+n，
α k-1＝tanh(L(c k-1))，β k-1＝1，
Figure GSA00000122954000065
Back to iterative computation:
k＝g(N l-P)+n，
Figure GSA00000122954000066
The demodulation bit soft value calculates:
y k = | a f , n g + a b , n g + r k · ( + 1 ) σ 2 | - | a f , n g + a b , n g + r k · ( - 1 ) σ 2 | , if , k ∈ I d .
Step 5) is based on LDPC coding bound confidence propagation decoding algorithm:
Input: y ( l ) = { y k ( l ) } k ∈ I d ,
Output:
Figure GSA00000122954000072
And decoding output code word c.
If step 6) decoding code word can satisfy the verification of LDPC check matrix or arrive maximum decoding number of times, then decoding stops, and continues to carry out otherwise forward step 3) to.
Wherein, step 5) is that this coding bound can utilize bipartite graph effectively to represent, as Fig. 2 according to LDPC coding bound confidence propagation decoding algorithm.
The present invention proposes a kind of correction M﹠amp; M frequency offset estimating algorithm, its characteristic feature are can make full use of the sample that external information that iterative decoding provides and segmentation add up after modulating to improve the work thresholding.The present invention is based on the Tikhonov algorithm in conjunction with revising M﹠amp; M frequency offset estimating algorithm has proposed the piecemeal startup, block size recovers and demodulating algorithm with the carrier wave that iteration constantly increases, this algorithm can make full use of the iteration external information and finish the recovery of carrier wave frequency deviation and phase place and obtaining of demodulating data, can effectively solve the difficult problem that frequency offset estimating under the utmost point low signal-to-noise ratio and decoding start mutual restriction.
Beneficial effect:
1. the characteristics of iterative demodulation decoding scheme provided by the invention are that the demodulation sign indicating number is independent substantially, and both carry out information interaction by external information and improve constantly performance;
2. scheme provided by the invention is simple and practical, is easy to Digital Implementation;
3. correction M﹠amp provided by the invention; The M frequency deviation estimating modules can provide in decoding and can make full use of this external information under the condition of external information and improve performance;
4. correction M﹠amp provided by the invention; The M frequency deviation estimating modules is carried out the sample operation that adds up based on segmentation, has improved work thresholding disease greatly and has effectively reduced implementation complexity;
5. the carrier wave that piecemeal provided by the invention starts, block size constantly increases with iteration recovers and demodulating algorithm can make full use of the iteration external information and finishes the recovery of carrier wave frequency deviation and phase place and obtaining of demodulating data, can effectively solve the difficult problem that frequency offset estimating and decoding under the utmost point low signal-to-noise ratio start mutual restriction.
6. irrelevant in carrier wave recovery provided by the invention and demodulation module and the system nature with concrete channel coding method, thus widely applicable, applicable to the good sign indicating number of typical cases such as LDPC sign indicating number, Turbo code, convolution code;
7. the present invention is applied to typical permanent ginseng satellite channel, can obtain to approach the performance of decoding under the desirable awgn channel.
Description of drawings
Fig. 1 is the demodulating and decoding factor graph that the branch block size constantly increases with iteration;
Fig. 2 is the structure chart of a LDPC sign indicating number bipartite graph, i.e. the connection diagram of check-node and variable node, and variable node and check-node are designated as v and c respectively;
The BPSK receiver system performance of Fig. 3 example;
Abscissa is bit signal to noise ratio Eb/N0 among the figure, ordinate is bit error rate (BER), 3 from top to bottom expressions respectively of curve among the figure: the performance that the Tikhonov algorithm iteration is 60 times, the performance that algorithm iteration of the present invention is 60 times, 60 decoded performances of desirable coherent reception iteration.
All explanation of symbols:
v n: n variable node in the LDPC sign indicating number bipartite graph;
c m: m check-node in the LDPC sign indicating number bipartite graph;
L: iterations;
L: the coding code length in the frame;
B: the block count (initial piecemeal number) of coding codeword when iteration begins;
D: initial sub-block size;
P: lead yardage in each initial sub-piece;
B l: the block count of the coding codeword data of the l time iteration;
D l: the branch block size of the coding codeword data of the l time iteration;
N l: the piecemeal symbol size of the l time iteration (comprise coded identification and lead sign indicating number);
N s: a frame signal total sample number that receives;
F: revise M﹠amp; Segmentation accumulation length in the M frequency offset estimating algorithm;
N f: frame data are carried out sample length after segmentation adds up;
M﹠amp; M algorithm: document [M.Morelli and U.Mengali, " Feedforward frequency estimationfor psk:A tutorial review; " Eur.Trans.Commun.Related Technol., vol.9, Mar./Apr.2004, pp.103-116] in a kind of frequency offset estimating algorithm of providing;
Tikhonov algorithm: document [G.Colavolpe, A.Barbieri, and G.Caire, " Algorithms for iterativedecoding in the presence of strong phase noise; " IEEE J.Select.Areas Commun., vol.23, Sept.2005, pp.1748-1757] in a kind of carrier wave of providing recover and demodulating algorithm;
AWGN: additivity white Gaussian Profile noise.
Embodiment
It is rule (3,6)-LDPC sign indicating number of 1/2 that this example is selected code check for use, and code length is L=4096.The sub-piece number of the primary data of coding codeword is B=128, and the sub-block size D=32 of primary data and lead sign indicating number and be distributed in each initial sub-piece leads yardage P=1 in each sub-piece.The piecemeal number of the coded data of the l time iteration, branch block size are chosen as B respectively l=min (2 7-l, 128), D l=min (2 lD, 4096), min (x, y) minimum number among expression peek x and the y wherein.The piecemeal symbol size of the l time iteration (comprise coded identification and lead sign indicating number) is N l=D l+ min (2 l+ 1,128+1).Revise M﹠amp; Segmentation accumulation length F=32 in the M frequency offset estimating algorithm, parameter E=32.
The iterative demodulation coding/decoding method that the present invention proposes is as follows: receive a frame modulation signals whole frame, and be cut to a plurality of signal subspace pieces; The external information of initialization codes bit; According to the external information of coded-bit and a frame signal sample value that receives, adopt a kind of correction M﹠amp; The M algorithm carries out frequency offset estimating; Carry out the carrier wave recovery according to signal subspace block structure and above-mentioned frequency offset estimating, and calculate the soft value of demodulation of coded-bit in view of the above; Decoder receives the above-mentioned soft value of demodulation, finishes once decoding according to the degree of confidence propagation decoding algorithm, and the external information of output encoder bit; When the iterative decoding number of times reaches predetermined times, the output decoder value, otherwise the length of increase signal subspace piece repeats above operation and reaches stipulated number until decoding success or iterations.
Its concrete steps are as follows:
The step 1) parameter initialization: when sample position k for leading code position k ∈ I p, put L (c kThe ∞ of)=+ is when sample position k is Data Position k ∈ I p, L (c k)=0; Initialization iterations l=0.
Step 2) degree of confidence propagation decoding algorithm initialization: check-node is made as 0 to the transmission information of variable node.
Step 3) is based on receiving sample r and decoding external information L dCarry out and revise M﹠amp; The M algoritic module calculates frequency deviation:
Figure GSA00000122954000091
Step 4) is carried out based on the Tikhonov algorithm of signal subspace piece and is finished carrier wave recovery and demodulation:
1) to g (g=0 ..., B l-1) before and after the height piece carrier wave to iteration initialization:
a f , 0 g = 0 , a b , N l - 1 g = 0 .
2) in g sub-piece, carry out carrier wave recover before and after to iterative computation:
The forward direction iteration is calculated successively:
k＝g(N l-P)+n，
α k-1＝tanh(L(c k-1))，β k-1＝1，
Figure GSA00000122954000093
Calculate successively to iteration the back:
k＝g(N l-P)+n，
Figure GSA00000122954000101
The demodulation bit soft value calculates:
y k = | a f , n g + a b , n g + r k · ( + 1 ) σ 2 | - | a f , n g + a b , n g + r k · ( - 1 ) σ 2 | , if , k ∈ I d .
Step 5) is based on LDPC coding bound confidence propagation decoding algorithm:
Input: y ( l ) = { y k ( l ) } k ∈ I d ,
Output:
Figure GSA00000122954000104
And decoding output code word c.
If step 6) decoding code word can satisfy the verification of LDPC check matrix or arrive maximum decoding number of times, then decoding stops, and continues to carry out otherwise forward step 3) to.
The hypothesis channel is typical satellite constant-parameter channel in this example, and the initial normalization frequency deviation (with respect to symbol transmission speed) of channel is positioned at Δ fT=[-0.01,0.01 at random], and the channel unknown phase is the phase place between picked at random (0,2 π).This example is seen Fig. 3 in the performance under 60 iteration under the typical satellite constant-parameter channel.
Though reference wherein particular specific embodiment illustrates and illustrates the present invention, but, those of ordinary skill in the art will be understood that, under the situation that does not break away from the defined spirit and scope of claim that the present invention adds, can carry out various modifications on form and the details to the present invention.

Claims (7)

1. a modulation signals advances the iterative demodulation coding/decoding method of compensate of frequency deviation based on layer, it is characterized in that this method comprises the steps:
A. receive a frame modulation signals whole frame, and be cut to a plurality of signal subspace pieces;
B. the external information of initialization codes bit;
C. according to the external information of coded-bit and a frame signal sample value that receives, adopt a kind of correction M﹠amp; The M algorithm carries out frequency offset estimating;
D. finish the signal demodulation, the soft value of the demodulation of output encoder bit according to the sub-block structure of current demand signal and a kind of correction Tikhonov demodulating algorithm of above-mentioned frequency offset estimating execution;
E. decoder receives the above-mentioned soft value of demodulation, finishes once decoding according to the degree of confidence propagation decoding algorithm, and the external information of output encoder bit;
F. when the iterative demodulation number of times reaches prior predetermined times, the output decoder value, otherwise, increase the length of signal subspace piece, change the next iteration demodulation over to, also i.e. execution in step c once more)～step e).
2. modulation signals as claimed in claim 1 advances the iterative demodulation coding/decoding method of compensate of frequency deviation based on layer, it is characterized in that described step a) is encoded to the LDPC sign indicating number.
3. modulation signals as claimed in claim 1 advances the iterative demodulation coding/decoding method of compensate of frequency deviation based on layer, it is characterized in that described step a) is modulated to the B-PSK modulation.
4. modulation signals as claimed in claim 1 advances the iterative demodulation coding/decoding method of compensate of frequency deviation based on layer, it is characterized in that described step c) adopts a kind of correction M﹠amp; M frequency offset estimating algorithm, this algorithm at first utilize the external information of coded-bit to go modulation to received signal, add up to going modulated pattern to carry out segmentation then, and the sample value after segmentation adds up is again according to M﹠amp; M frequency offset estimating algorithm computation frequency deviation value.
5. modulation signals as claimed in claim 1 advances the iterative demodulation coding/decoding method of compensate of frequency deviation based on layer, it is characterized in that described step d) adopts a kind of correction Tikhonov demodulating algorithm, and this algorithm is based on the sub-block operations of independent signal; In each independent sub-piece, at first calculate forward metrics, and sample-by-sample is rotated correction according to the frequency offset estimating value to the forward direction sample, calculate the back then to tolerance, and sample-by-sample is rotated correction to the back to sample according to the frequency offset estimating value, last according to front and back to the soft value of the demodulation of metric calculation coded-bit.
6. modulation signals as claimed in claim 1 advances the iterative demodulation coding/decoding method of compensate of frequency deviation based on layer, it is characterized in that the demodulation of described step d) signal is based on the signal subspace block structure, calculate to the soft value of metric calculation and coded-bit the front and back of different sub-piece Tikhonov algorithms is independently, the accumulation of phase effect that this has effectively been avoided the frequency offset estimating error helps the decoder startup work after the demodulation.
7. modulation signals as claimed in claim 1 advances the iterative demodulation coding/decoding method of compensate of frequency deviation based on layer, it is characterized in that described step f) next iteration separates timing, the signal subspace agllutination is really modulated, the length of the signal subspace piece after the modulation will guarantee greater than a preceding iteration, this will effectively strengthen the precision that carrier wave recovers, and along with iteration improves constantly system's demodulation performance.
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CN106101039A (en) * 2016-06-07 2016-11-09 北京大学 A kind of based on the data auxiliary adjustable frequency deviation estimating method of precision
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CN102647377B (en) * 2012-05-18 2016-05-18 天津理工大学 A kind of frequency deviation correcting method and device based on data field piecemeal
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CN104009826A (en) * 2014-06-18 2014-08-27 西安电子科技大学 Frequency hopping anti-interference method based on error correction and erasure correction RS-Turbo concatenated codes
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CN110166171A (en) * 2018-03-19 2019-08-23 西安电子科技大学 Multielement LDPC code compensates high-performance decoding scheme based on the segmented of EMS
CN111600817A (en) * 2019-02-20 2020-08-28 天津光电通信技术有限公司 Serial hierarchical scheduling algorithm for factor graph iterative equalization
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