采用Turbo码的type Ⅲ HARQ性能分析

Performance analysis of type Ⅲ HARQ with Turbo codes

从理论研究和仿真分析两方面对type III HARQ在无线信道环境下的性能进行了深入研究,并与其它两种HARQ方案的性能进行了分析对比。应用更新理论,得出了type I HARQ和type II HARQ 方案分别在AWGN和Rayleigh衰落信道下吞吐量的闭式解,对于type III HARQ虽无闭式的解,但给出了积分形式的解。此外,采用Turbo码为前向纠错码,对三种HARQ分别在AWGN和Rayleigh衰落信道条件下的吞吐量和残余FER等性能做了仿真。结果显示,对于任意的BF信道,包括AWGN信道,type III HARQ的性能总是比type II HARQ好,而type II HARQ总比type I HARQ好。而且,type III HARQ的优越性在Rayleigh衰落信道下更加突出。

The performance of type III HARQ with code combing in wireless channel environments is lucubrated through both theoretical research and simulation analysis, and is compared with those of the other two HARQ schemes, viz. type I HARQ and type II HARQ with chase combining. All the research in this paper is carried out on both the AWGN channel and Rayleigh fading channel, respectively. By applying renewal theory and channel coding theorem, we obtained the closed-form solutions to the typeⅠHARQ and type II HARQ. For the type III HARQ, although the closed-form solution is not obtained, we did get the integral solution. Furthermore, using Turbo codes as forward error correction, the throughput and the residual FER of the three HARQ schemes are simulated. It shows that for arbitrary block fading channel, comprising AWGN channel, the performance of type III HARQ is always better than that of type II HARQ, whereas type II HARQ is always better than that of type I HARQ. Especially, the advantage of type III HARQ will be more prominent on Rayleigh fading channel.