Irregular 8PSK mapping for variable length codes with small blocks in a BICM-ID system

Abstract

Iterative decoding is an effective technique to approach the channel capacity for very large block sizes with enough iterations. However, due to the limitation of bandwidth and delay, small blocks of data are much more commonly applied in practical communications, and low iteration counts are usually preferred for both decoding complexity and delay consideration. In such cases, the design rules of near capacity decoding-which is generally asymptotic with respect to the block size-may cause inferior performance. To overcome this problem for 8-phase shift keying (8PSK) modulated variable length codes (VLCs), an irregular mapping scheme for the transmission system of bit-interleaved coded modulation with iterative decoding (BICM-ID) is studied in this paper. A submapping searching algorithm and an irregular mapping optimization algorithm are proposed aiming at maximizing the extrinsic mutual information after a target number of iterations. Simulation results show that for small data block size with a low iteration count, our scheme has advantages with respect to the existing near capacity systems optimized by the asymptotic tools.

Variable length error correcting code for image in OFDM and PAPR reduction

“…Data transmission needs to be coded by source code to remove redundancy and coded by channel code for error detection and correction to decrease the channel effect, the channel code increases the data redundancy to recover the channel errors, therefore it's better to combine the source and channel codes in single code to reduce redundancy and correct errors at the same time [12]. Variable length code (VLC) is widely used for audio and video compression, variable length error correcting code (VLEC) is a class of VLC with free distance between the code words like the channel code, and therefore VLEC offers source coding and channel coding by the single code [13]. In this work we use VLEC code in the OFDM system to decrease data transmitted size and at the same time to detect and correct errors, PAPR is a common problem in OFDM system, which will decrease the transmission efficiency, therefore; it's important to know the relationship between the transmission of image coded with VLEC code and PAPR values, several methods are tested for PAPR reduction.…”