PAPR Reduction using CPM Mappers and SLM in OFDM Systems

Orthogonal Frequency Division Multiplexing (OFDM) system with Continuous Phase Modulation (CPM) mappers is considered. Such a system is known to provide superior bit error rate performance by virtue of the memory introduced by the CPM mapper compared to OFDM systems with conventional memoryless mappers such as BPSK and QPSK. In this paper, the ability of CPM mappers in an OFDM system to reduce Peak-to-Average Power Ratio (PAPR) is examined as a function of modulation parameters of mappers and the number of subcarriers used in the system. Firstly, three subclasses of CPM mappers, namely, single-h CPFSK, multih CPFSK, and Asymmetric multi-h CPFSK are considered and their PAPR performance is assessed. Next, these mappers in conjunction with SLM technique are considered and their PAPR performance is examined. A comparison of the PAPR reduction capability of CPM mappers relative to memoryless BPSK mappers in an OFDM system is presented. It is noted that, in general, CPM mappers offer superior PAPR performance compared to memoryless mappers in an OFDM system. Also, it is shown that CPM mappers with SLM technique in an OFDM system can offer significant improvement in PAPR performance.