Novel PMEPR Control Approach for 64- and 256-QAM Coded OFDM Systems

Orthogonal frequency division multiplexing (OFDM) is a prevalent telecommunication technology to mitigate multipath distortion with high-order modulations such as quadrature amplitude modulation (QAM). However, uncoded OFDM systems also have a serious drawback of high peak-to-mean envelope power ratio (PMEPR). On the other hand, coded OFDM systems can reduce the PMEPR problem but often lead to low code rates. There is thus a tradeoff between PMEPR and code rate in the design of OFDM systems. In this paper, PMEPR reduction for OFDM 64- and 256-QAM sequences is comprehensively studied. Four new families of 64-QAM sequences and seven new families of 256-QAM sequences are proposed to achieve the lowest PMEPR, the highest code rate, or the tradeoffs between these two metrics. Through the comparison with all other OFDM 16- or 64-QAM sequences, these new families of OFDM sequences can facilitate higher code rates. Furthermore, many of these new sequences have lower PMEPR than other OFDM sequences. Adjustment of the tradeoff between PMEPR and code rate can be made to meet the stringent demand in low PMEPR or the need for high code rate subject to various system requirements. Moreover, the construction method of the proposed new sequences is quite simple.