Search For Selected Mapping To Reduce PAPR In MC-CDMA System

MC-CDMA is an integrated technology of OFDM and CDMA. This technology is considered as the core technology of the future 4G wireless communications. It keeps the advantages of OFDM and CDMA, and can be used for multimedia data transmission. However, the high peak-to-average power ratio (PAPR) of MC-CDMA signals results in nonlinear distortion and degradation of bit error ratio (BER)performance, which is the obstacle of utilities of MC-CDMA.At numerous methods of reducing peak-to-average power ratio (PAPR), the selected mapping (SLM) is a well effective method. In this thesis, the SLM methods of reducing PAPR of MC-CDMA are researched. Some valuable conclusions are acquired. The main contents are as follows:1. An adaptive choosing the copy-frame number model of SLM is proposed. In the SLM, it needs more IFFT process whose number is equal to copy-frame number, this cause the high complexity of the system. An adaptive choosing the copy-frame number model of SLM is proposed in this thesis. At the basic of the BER meets some qualification, it can choose out the very suit copy-frame number of system though the adaptive choosing the copy-frame number arithmetic. This makes the systemic complexity keeping in the lowest floor, and at the same time reduces the PAPR effectively.2. A new phase sequence for SLM in MC-CDMA system is proposed. Selected mapping (SLM) is an effective method to reduce PAPR. In SLM the direct infection of PAPR is what sequence is used as the phase sequence. This thesis proposes using a new Pseudo Random Interferometry code as the phase sequence for SLM to reduce PAPR of MC-CDMA. The simulation results show that the proposed sequence can effectively reduce PAPR, and is better than Walsh-Hadamard, Golay sequence. And though the simulation of BER curve presents OFDM and MC-CDMA systems have preferably performance.