Abstract
We propose a coding scheme based on the use of systematic linear codes with low-density generator matrix (LDGM codes) for channel coding and joint source-channel coding of multiterminal correlated binary sources. In both cases, the structures of the LDGM encoder and decoder are shown, and a concatenated scheme aimed at reducing the error floor is proposed. Several decoding possibilities are investigated, compared, and evaluated. For different types of noisy channels and correlation models, the resulting performance is very close to the theoretical limits.
Highlights
The introduction of turbo codes [1] and low-density parity check (LDPC) codes [2, 3, 4, 5] has been one of the most important milestones in channel coding during the last years
Considering an additive white gaussian noise (AWGN) channel, even for very high signal to noise ratios (4 dB above the Shannon limit), the residual BER for each block is always higher than 10−2, and presents oscillations with the iteration number
For schedules I and II, no error floor appeared after simulating more than 10 000 blocks, and the resulting performance is very close to the theoretical limits
Summary
The introduction of turbo codes [1] and low-density parity check (LDPC) codes [2, 3, 4, 5] has been one of the most important milestones in channel coding during the last years. Standard LDPCs present a higher encoding complexity, but the decoder is simpler. The first schemes for compression of multiterminal correlated sources using channel codes were proposed in [12, 13, 14], and the use of turbo-like codes in this problem was proposed in [15, 16]. The case in which both sources are transmitted through separated noisy channels has appeared only in [25, 26], where turbo codes were proposed to perform joint source-channel coding of correlated sources. The contents of this paper are as follows: Section 2 introduces systematic LDGM codes and presents the decoding algorithm in relation with that of standard LDPC codes.
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