OFDM/OQAM系统限幅补偿IAM信道估计方法

IAM channel estimation with clipping compensation for OFDM/OQAM system

基于偏移正交幅度调制的正交频分复用(offset quadrature amplitude modulation/orthogonal frequency division multiplexing,OFDM/OQAM)系统信道估计方法中,干扰近似法(interference approximation method,IAM)具有估计精度高的特点,是该系统常用的信道估计方法。然而,在OFDM/OQAM信号发送和接收过程中,高功率放大器(high power amplifier,HPA)对信号的限幅作用导致IAM信道估计精度下降。为了研究不同IAM导频结构下的系统性能受限幅影响的程度,针对导频峰均比问题,提出了局部互补累积分布函数,并研究了不同限幅门限作用下,系统比特误码率性能和信道估计归一化均方误差性能。为了补偿HPA的限幅作用对系统的影响,提出了一种导频限幅补偿方法 ,该方法不需要发送额外的补偿信息,仅仅需要根据导频结构计算并在接收端补偿。仿真结果验证了补偿方法的有效性,并且导频信号受限幅影响越严重,补偿效果越好。

Interference approximation method（IAM）,one of the channel estimation methods for orthogonal frequency division multiplexing/offset quadrature amplitude modulation（OFDM/OQAM）system,is a usual method which has a high estimation accuracy.However,in processing of transmission and receiving of the OFDM/OQAM signal,the signal can be influenced by clipping of high power amplifier（HPA）which can lead to a recession of the IAM channel estimation accuracy.To research the influences of different IAM structures,aiming at peak-to-average ratio of pilot,this article proposes a part-complementary cumulative distribution function,researches the bit error ratio performance of the system and normalizes mean square error performance of channel estimation in different clipping thresholds of IAM channel estimation accuracy.To compensate the influence of the HPA clipping effect,this article proposes a method of clipping compensation.This method does not need to transmit extra clipping information and just calculates with the pilot structure and compensates at the receiver.Simulation result shows that the method works and the worse the clipping influence,the better the compensation effect.