A Study on Symbol and Sub-Carrier Mapping Techniques for MC-CDMA based on LDPC Code with Progressively Increased Column-Weight

This paper proposes a symbol mapping scheme on sub-carriers in use of MC-CDMA (multi carrier-code division multiple access) and LDPC (low-density parity-check) codes. Aiming at high spectrum efficiency, 16QAM modulation and LDPC codes with the PICW (progressively increased column-weight) are used here. The PICW-LDPC code is proposed in our previous studies and is proved to have better decoding performance as rate-compatible LDPC codes. By adopting the proposed symbol mapping method, the FER (frame error rate) performance of the PICW-LDPC code is improved, the required E_s/N₀ is reduced by 0.12 dB in an AWGN channel. In order to improve FER performance in the multi-path channel, the proposed sub-carrier mapping is further applied, and the required E_s/N₀ can also be reduced by 2.32 dB