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Concatenated code iterative decoding method for correcting synchronization and substitution errors

An iterative decoding and error-replacement technology, applied in the iterative decoding field of concatenated codes, can solve the problem of high complexity, and achieve the effect of expanding the ability to correct synchronization errors and obvious performance gains.

Active Publication Date: 2018-06-08
TIANJIN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] On the one hand, the DM construction needs to change the existing coding scheme, and the complexity is very high; on the other hand, there is room for further improvement in the performance of the convolutional code decoding algorithm that can correct synchronization errors and replace errors

Method used

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  • Concatenated code iterative decoding method for correcting synchronization and substitution errors
  • Concatenated code iterative decoding method for correcting synchronization and substitution errors
  • Concatenated code iterative decoding method for correcting synchronization and substitution errors

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Embodiment 1

[0056] In order to identify synchronization errors in transmission and correct synchronization errors and substitution errors in the sequence at the same time, an embodiment of the present invention provides an iterative decoding method for concatenated codes that can correct synchronization and substitution errors, see Figure 1 to Figure 10 , described in further detail.

[0057] In the embodiment of the present invention, the correct symbol of the decoding output of the outer code, that is, the RS code, is passed to the inner decoder, that is, the Viterbi decoder based on the extended trellis graph, and the extension of the convolutional code that takes into account the synchronization error is reinitialized. Grid graph, through effective clipping of possible paths, avoids impossible paths during routing backtracking, thereby obtaining iteration gain. See the overall process figure 1 , the detailed process is described as follows:

[0058] 101: Generate an identifiable co...

Embodiment 2

[0066] The scheme in embodiment 1 is further introduced below in conjunction with specific drawings and calculation formulas, see the following description for details:

[0067] One, the concrete operation of step 101 among the embodiment 1 is as follows:

[0068] (1.1) For convolutional codes (n,k,m), for each state S in the original trellis graph j (0≤j≤2 m -1), add n-1 additional states It is used to describe the change of the decoding start position at each moment caused by synchronization errors, such as image 3 Schematic diagram of adding n-1 additional states;

[0069] (1.2) According to the maximum number of symbol shifts ρ considered in decoding, each additional state in (1.1) Expanded to 2ρ+1 states Generate a complete extended grid map;

[0070] Among them, b represents the drift of the decoded output symbols caused by synchronization errors, such as Figure 4 For the complete expanded trellis plot taking bit-shift and sign-shift into account.

[0071] (...

Embodiment 3

[0125] A specific embodiment is given below to illustrate the feasibility of the iterative decoding method of the RS code concatenated convolutional code correcting the synchronization error provided by the embodiment of the present invention.

[0126] In the embodiment of the present invention, the (255, 223) RS code is used as the outer code, and the (3, 1, 6) convolutional code whose generator polynomials are 117, 127, 155 is used as the inner code as a special case. In step (2), the block interleaving method is adopted, the interleaving depth is 24, and the coded convolutional code block length is 594 bits. The maximum symbol shift considered during decoding is ρ=5, and the maximum number of iterations is 2.

[0127] Figure 11 Give the bit error rate for transmitting one convolutional code block per frame and five convolutional code blocks per frame without substitution errors. Figure 12 gives the substitution probability p e =0.01, the bit error rate of transmitting ...

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Abstract

The invention discloses a concatenated code iterative decoding method for correcting synchronization and substitution errors. The method comprises the steps of generating an expanded grid diagram capable of describing a synchronization error, decoding each frame of received data through utilization of a bidirectional viterbi decoding algorithm based on the expanded grid diagram, and carrying out RS code decoding; and reinitializing convolutional codes through utilization of accurately decoded RS code symbols, taking the expanded grid diagram after the synchronization error occurs into consideration, and further carrying out viterbi decoding and RS code decoding. According to the method, the expanded grid diagram is effectively clipped through adoption of the accurately decoded RS code symbols, so the complexity of the grid diagram is reduced, the integrated iterative decoding complexity is reduced, and the superior error correction capability is achieved.

Description

technical field [0001] The invention relates to the field of digital communication error control coding, in particular to an iterative decoding method of concatenated codes for correcting synchronization and replacing errors. Background technique [0002] In digital communication and storage systems, noise can cause bit flips or symbol errors, which are generally called substitution errors. For channels with only substitution errors, such as errors under Additive White Gaussian Noise (AWGN) channels, existing high-efficiency coding techniques, such as Turbo codes, LowDensity Parity Check (LowDensity Parity Check, LDPC) codes etc., can effectively correct the substitution error caused by additive noise in the received sequence, and its performance is very close to the Shannon limit. However, the above encoding techniques all assume that the sending end and the receiving end can achieve ideal synchronization, but many actual communication systems have timing deviation problem...

Claims

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Application Information

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IPC IPC(8): H03M13/11H03M13/29
CPCH03M13/1128H03M13/2948
Inventor 陈为刚刘元松
Owner TIANJIN UNIV
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