The Research Of OFDM System Based On IDMA

Like CDMA, OFDM is one of the main topics of today's wireless communications and an important part of the mobile communication. How to use them effectively and how to improve the quality of communication are the most concerns of the scientists and technicians. Based on Code Division Multiple Access (CDMA), Li Ping and his coworker have proposed Interleave Division Multiple Access (IDMA), which has a very low system complexity, and it is an important technology in the multiple access technology.This paper firstly overview the research status both domestic and overseas, and then analyze the principle of OFDM system, The basic principle and the implementation of the multiple access technology are introduced. Then, for the IDMA system, IDMA system, the system is presented with explanation for the transmitter and the receiver respectively. The chip-by-chip iterative mufti-user detection is explained with emphasis on element signal estimate algorithm and implementation. Moreover, an OFDM based IDMA system model is constructed the transmitter and receiver structures are introduced together with corresponding multi-user detection method. Simulation is done to investigate the bit-error-rate(BER) performance, and then the bit-error-rate is compared with the system of OFDM-CDMA. At the late part of the paper, OFDM-IDMA system associated with ARQ protocol is proposed. The system of ARQ-OFDM-IDMA is analyzed theoretically. Simulation results show that ARQ is able to improve system performances including BER. At last we compared the bit-error-rate with the blind orthogonal multi-user detection of CDMA system based on subspace proposed in this paper.