地空信道基于OFDM/OQAM系统的波形自适应算法

Waveform adaptive algorithm for OFDM/OQAM system under air-ground channel

传统的正交频分复用/偏移正交幅度调制(OFDM/OQAM)系统波形自适应设计主要针对具有非指数型时延功率谱和非U型多普勒功率谱的信道模型对波形进行优化,而实际中,波形自适应设计会因不同的信道模型产生不同的信道匹配准则系数。结合地空信道模型和扩展高斯函数的特性,在传统基于信干噪比(SINR)优化的OFDM/OQAM系统波形自适应算法的基础上提出一种新的OFDM/OQAM系统波形自适应设计算法。该算法引入信道匹配系数β,通过信道匹配准则建立波形时频域间隔与信道最大多径时延、最大多普勒频移的关系,再结合传统SINR优化函数计算扩展因子参数,将参数反馈给发送端并调整发送端和接收端的滤波器达到波形自适应的目的。仿真结果表明,4QAM和16QAM调制下,信道匹配系数β的引入在系统误码性能上均有1. 0 d B以上的改善。

The conventional adaptive waveform design of orthogonal frequency division multiplexing/offset quadrature amplitude modulation(OFDM/OQAM) system are mainly for the channel model of non-exponential-type delay power spectrum and non-U-type Doppler power spectrum. However,waveform adaptive design results in different channel matching criterion coefficients due to different channel models in practice. Therefore,this paper discussed the characteristics of ground air channel model and extended Gaussian function and proposed a new OFDM/OQAM waveform adaptive algorithm based on the traditional SINR-adaptive waveform design. This algorithm introduced a matching coefficient β into the traditional waveform matching criterion,which established the relation between the time-frequency domain and the maximum multipath delay-Doppler frequency shift of the waveform. Combined with the traditional optimization function of SINR,it optimized the parameters of the pulse shaping filter and then fed back to the transmitter to adjust the filter banks at the transmitter and receiver. Simulation results show that,under the modulation of 4QAM and 16 QAM,the channel matching coefficient β has an improvement of 1. 0 d B or more in the system error performance.