基于信道辨识的自适应Turbo-OFDM系统性能研究

研究了信噪比对系统性能影响的规律,将信噪比分布分为高信噪比区、中信噪比区和低信噪比区3个区域。当部分平均信噪比分别取3个区域典型值时,引入迭代增益,判断典型信道状态对应的最佳迭代次数。将数据子信道对应的接收信噪比进行排序,计算部分平均信噪比,利用其进行聚类分析,对当前信道进行辨识,在不同的信道状态下,自适应选择迭代译码次数。仿真结果说明,在平坦慢衰落信道下,采用OFDM系统中基于信道辨识的自适应Turbo码译码算法,可以兼顾系统性能和译码速度,得到较低的平均误比特率和较高的平均译码速度。

Decreasing Average BER and Increasing Average Decoding Speed of Adaptive Turbo-OFDM System

Aim.Existing adaptive decoding algorithms~() for Turbo-OFDM system can,in our opinion,still be improved.We present a new algorithm that we believe is better;besides,it is simple and robust.In the full paper,we explain in detail our new algorithm.In the abstract,we just add some pertinent remarks to listing the two topics of explanation:(1) the model of our Turbo-OFDM system;the subtopics are the model of channel(subtopic 1.1) and the model of our adaptive Turbo-OFDM system based on channel classification(subtopic 1.2);under subtopic(1.2),Fig.1 in the full paper gives the schematic of our adaptive Turbo-OFDM system;(2) the performance characteristics of our adaptive Turbo-OFDM system based on channel classification;under topic(2) we derive eqs.(2) through(8);the simulation results are given in Figs.2 and 4 and Tables 1 and 2 in the full paper.Simulation results show preliminarily that,over slow flat fading channel,the proposed algorithm obtains superior performance with lower average BER and higher average decoding speed;in other words,the decoding process is speeded up at the cost of sacrifice in BER with high received SNRs,and the BER is decreased at the cost of sacrifice in decoding speed with low received SNRs.The proposed algorithm can decrease BER by 24% compared with 4-fixed-iterations decoding algorithm,and speed up the decoding process by 26% compared with 8-fixed-iterations decoding algorithm.