Algorithm For Non-binary LDPC Codes Research Articles

An Adaptive Single/Multiple Symbol Flipping Decoding Algorithm for Non-Binary LDPC Codes

This letter presents an adaptive single/multiple distance-symbol flipping decoding algorithm with prediction (ASMD-SFDP). Different from the D-SFDP, the presented algorithm consider both the global maximization and sec-maximization values of the reliability fluctuation quantity (RFQ). Flipping operation is performed only when the global maximization is greater than or equal to zero. Furthermore, a new flipping strategy is introduced based on the numerical gap between the global maximization and sec-maximization. The flipping operation is performed adaptively: 1) If the gap is greater than or equal to a designed threshold, only single symbol is flipped; 2) Otherwise, multiple symbols are flipped. Simulation results show that the presented algorithm can achieve a significant performance gain of 0.4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim $ </tex-math></inline-formula> 0.5 dB compared with the original D-SFDP algorithm. More interestingly, the presented algorithm also shows a much faster convergence speed.

Multiple-Votes Parallel Symbol-Flipping Decoding Algorithm for Non-Binary LDPC Codes

A novel decoding algorithm for non-binary low density parity check (NB-LDPC) codes is proposed. The algorithm builds on the recently designed parallel symbol-flipping decoding (PSFD) algorithm and combines a technique of error estimation and a method of multiple voting levels from each unsatisfied check-sum to the corresponding variable nodes. Simulations results, performed on a number of NB-LDPC codes of various lengths and column weights constructed using several methods, show that the new algorithm not only avoids using code-dependent voting threshold but also improves the error rate performance of the PSFD algorithm, particularly for low column weight parity-check matrices.

A Variant of the EMS Decoding Algorithm for Nonbinary LDPC Codes

This letter is concerned with low-complexity decoding algorithms for nonbinary low-density parity-check (NB-LDPC) codes. A new truncation rule based on an adaptive threshold μ is proposed for the extended min-sum (EMS) algorithm. The threshold μ is determined by the mean of the message vector. Therefore, it can be matched to channel observation and decoding iteration. The resulting algorithm is referred to as μ-EMS algorithm. Simulation results show that the μ-EMS algorithm performs almost as well as the Q-ary sum-product algorithm (QSPA). Simulation results also show that the μ-EMS algorithm is simpler than the other X-EMS algorithms for NB-LDPC over high order finite fields.

Trellis-Based Extended Min-Sum Algorithm for Non-Binary LDPC Codes and its Hardware Structure

In this paper, we present an improvement and a new implementation of a simplified decoding algorithm for non-binary low density parity-check codes (NB-LDPC) in Galois fields GF(q). The base algorithm that we use is the Extended Min-Sum (EMS) algorithm, which has been widely studied in the recent literature, and has been shown to approach the performance of the belief propagation (BP) algorithm, with limited complexity. In our work, we propose a new way to compute modified configuration sets, using a trellis representation of incoming messages to check nodes. We call our modification of the EMS algorithm trellis-EMS (T-EMS). In the T-EMS, the algorithm operates directly on the deviation space by considering a trellis built from differential messages, which serves as a new reliability measure to sort the configurations. We show that this new trellis representation reduces the computational complexity, without any performance degradation. In addition, we show that our modifications of the algorithm allows to greatly reduce the decoding latency, by using a larger degree of hardware parallelization.

A Simplified Min-Sum Decoding Algorithm for Non-Binary LDPC Codes

Non-binary low-density parity-check codes are robust to various channel impairments. However, based on the existing decoding algorithms, the decoder implementations are expensive because of their excessive computational complexity and memory usage. Based on the combinatorial optimization, we present an approximation method for the check node processing. The simulation results demonstrate that our scheme has small performance loss over the additive white Gaussian noise channel and independent Rayleigh fading channel. Furthermore, the proposed reduced-complexity realization provides significant savings on hardware, so it yields a good performance-complexity tradeoff and can be efficiently implemented.