Analysis For PMEPR Reduction In OFDM Systems Based On Constructing Sequences

The OFDM technology has been applied in many wireless communication standards,such as IEEE802.11, IEEE802.16Mobile and3GPP-LTE, for its capability of mitigatingthe multipath fading effects. However, such applications bring several new problems, suchas high PMEPR of the transmitted signals. For OFDM signals with high PMEPR, highpower amplifiers (HPA) with a large linear range and high complexity digital-to-analogconverters (DAC) are required to minimize signal distortions, which are expensive andenergy inefficient. Therefore, a robust OFDM system should have a low PMEPR.One approach for PMEPR reduction in OFDM systems is to use Golaycomplementary sequences as codewords, which can be constructed by cosets of theclassical Reed-Muller codes. Although, through this approach, the OFDM systems canachieve the PMEPR of at most2, it results in an unacceptable performance on the code rateas the length of the sequences increases. As the research deepens, people turn to studyanother type of sequences, which generalize Golay complementary sequences and areknown as near-complementary sequences, in order to improve the code rate with a slightloss on the PMEPR performance. Constructions of Golay complementary sequences andnear-complementary sequences have been considered in the cases of16-quadratureamplitude modulation (QAM) and64-QAM constellation for years. However, in order toimprove the performance of the code rate, more16-QAM near-complementary sequencesneed to be constructed. In particular, a construction of64-QAM near-complementarysequences is still unknown.In this paper, new families of16-QAM Golay complementary and near-complementar–y sequences are proposed. When applied for OFDM systems, the proposed16-QAMconstructions can achieve a low PMEPR. Futhermore, we propose a construction of64-QAM near-complementary sequences with a low PMEPR upper-bound, which may bethe first proven family.