Chao Yu Chen

Two Low-Complexity Reliability-Based Message-Passing Algorithms for Decoding Non-Binary LDPC Codes

This paper presents two low-complexity reliability-based message-passing algorithms for decoding LDPC codes over non-binary finite fields. These two decoding algorithms require only finite field and integer operations and they provide effective trade-off between error performance and decoding complexity compared to the non-binary sum product algorithm. They are particularly effective for decoding LDPC codes constructed based on finite geometries and finite fields.

Complete complementary codes and generalized reed-muller codes

Due to ideal autocorrelation and cross-correlation properties, complete complementary codes (CCCs) can be employed in CDMA systems to eliminate the multiple-access interference. In this letter, we propose a direct general construction of CCCs from cosets of the first-order Reed-Muller codes, which includes previous results as a special case. The larger number of CCCs constructed by our method can provide advantages in applications to cellular CDMA systems.

A binary message-passing decoding algorithm for LDPC codes

This paper presents a soft reliability-based binary message-passing algorithm for decoding LDPC codes. This algorithm outperforms the existing weighted bit-flipping algorithms with much less computational complexity. It is particularly effective for decoding LDPC codes constructed based on finite-geometries and finite fields. The proposed algorithm can be simplified for applications in communication or storage systems where either soft reliability information is not available to the decoder or a simple decoder is needed.

Complementary sets and reed-muller codes for peak-to-average power ratio reduction in OFDM

One of the disadvantages of orthogonal frequency division multiplexing (OFDM) systems is the high peak-to-average power ratio (PAPR) of OFDM signals. Golay complementary sets have been proposed to tackle this problem. In this paper, we develop several theorems which can be used to construct Golay complementary sets and multiple-shift complementary sets from Reed-Muller codes. We show that the results of Davis and Jedwab on Golay complementary sequences and those of Paterson and Schmidt on Golay complementary sets can be considered as special cases of our results.

Parallel Symbol-Flipping Decoding for Non-Binary LDPC Codes

A new low-complexity parallel symbol-flipping decoding algorithm for non-binary low-density parity-check (NB-LDPC) codes is proposed. The algorithm outperforms quite a number of existing reliability-based message-passing algorithms, and its computation complexity is smaller than that of almost all the previously proposed iterative decoding algorithms for NB-LDPC codes. It is suitable for decoding NB-LDPC codes whose parity-check matrices have large column weights.

Complementary Sets of Non-Power-of-Two Length for Peak-to-Average Power Ratio Reduction in OFDM

Golay complementary sequences and complementary sets have been proposed to deal with the high peak-to-average power ratio (PAPR) problem in orthogonal frequency division multiplexing (OFDM) system. The existing constructions of complementary sets based on generalized Boolean functions are limited to lengths, which are powers of two. In this paper, we propose novel constructions of binary and nonbinary complementary sets of non-power-of-two length. Regardless of whether or not the length of the complementary set is a power of two, its PAPR is still upper bounded by the size of the complementary set. Therefore, the constructed complementary sets can be applied in practical OFDM systems where the number of used subcarriers is not a power of two. In addition, while the binary Golay complementary pairs exist only for limited lengths, the constructed binary complementary sets of size 4 exist for more lengths with PAPR at most 4.

Cell Search for Cell-Based OFDM Systems Using Quasi Complete Complementary Codes

Establishing a radio link in cell-based mobile communication systems involves searching and synchronizing the downlink known pattern of sequences associated with the base stations. The performance of the searching process, often referred to as cell search, depends greatly on the employed preamble sequences. In this paper, we propose a construction of quasi complete complementary codes (QCCCs) from Reed-Muller codes and, due to their good auto-correlation and cross-correlation properties, a preamble structure based on QCCCs. Furthermore, the constructed QCCCs have low peak-to-average power ratios (PAPRs) and hence are suitable for use in orthogonal frequency division multiplexing (OFDM) systems. Simulation results show that the QCCC-based preambles outperform the preambles employed in the WiMAX system, both in terms of PAPR and cell search performance. Moreover, the rich algebraic structures of QCCCs potentially admit low-complexity encoding and decoding.

A Novel Construction of Z-Complementary Pairs Based on Generalized Boolean Functions

Binary Golay complementary pairs exist for quite limited lengths whereas the binary Z-complementary pairs (ZCPs) are available for more lengths. Therefore, the ZCPs can potentially find more engineering applications. In this letter, we propose a novel construction of binary and nonbinary (

Convolutional codes for peak-to-average power ratio reduction in OFDM

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A Novel Construction of Complementary Sets With Flexible Lengths Based on Boolean Functions

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