OFDMA系统降低PAPR的DCT-ACE算法

DCT-ACE algorithm for PAPR reduction in OFDMA system

针对正交频分多址(OFDMA)系统的高PAPR问题,提出一种离散余弦变换(DCT)和动态星座扩展(ACE)的联合算法。首先对调制信号在频域进行DCT变换,从而降低大峰值信号出现的概率。对信号做星座扩展,通过改变星座点位置,减少信号同相的概率,以此降低OFDMA系统的PAPR。在16QAM的OFDMA信号模型下对新算法PAPR、计算复杂度和误码率(BER)进行仿真分析,与DCT算法、ACE算法和一些改进算法相比,所提算法在不增加复杂度的前提下,具有更强的PAPR抑制能力,且基本不会降低BER性能。

A joint algorithm of discrete cosine transform (DCT) and convex set - mapped active constellation expansion (ACE) is proposed to reduce the PAPR (peak -to -average power ratio) of OFDMA (orthogonal frequency -division multiple access)system. The DCT is carried out for the modulated signal in the frequency domain to reduce the occurrence probability of high peak signal,and then constellation expansion is performed for the signal to reduce the in-phase probability of signal by changing the positions of constellation points,by which the PAPR of OFDMA system is reduced. The PAPR,computational complexity and bit error rate (BER) of the new algorithm are simulated and analyzed by using the 16QAM OFDMA signal model. In comparison with the DCT algorithm,ACE algorithm and other improved algorithms,the proposed algorithm has higher PAPR suppression ability and can remain the BER performance without increasing the complexity.