分组协同中继系统性能研究以及分组长度性能影响分析

Performance analysis of packet cooperative relaying system and the effect of packet length on performance

针对AF(amplify-and-forward)和DF(decode-and-forward)2种转发模式,分析了分组协同中继通信系统在高信噪比下的误帧率性能,并研究了帧长对误帧率的影响。研究表明,以误帧率为准则,AF和DF模式都取得了相同的分集增益,但是编码增益不一样,并且编码增益与帧长有关。与现有的研究结论不一样,考虑到实际的分组长度,DF总是能够获得较AF更好的性能,帧越短DF的优势越明显;当帧长足够大时AF能够获得和DF相近的性能。还研究了最优的中继位置,对于AF系统,最优的中继位置总是位于源和目的节点中点处;而对于DF系统,当帧长增大时最优的中继位置将从靠近源处逐渐移至中点处。

The packet error rate（PER） of the packet cooperative relay system for both（amplify-and-forward） and DF（decode-and-forward） schemes in the high signal-to-noise ratio（SNR） region was analyzed,and the effect of packet length on PER performance was studied.It is shown that both AF and DF achieve the same diversity gain in terms of PER,but with different coding gains depending on packet length.Different from the prior research,if considering practi-cal packet lengths,the DF scheme always achieves better performance than the AF scheme,with shorter packet length,the advantage of DF over AF is more obvious.For large enough packet length,AF performance approaches that of DF.It is also found that the optimal relay will always be located in the middle of the two nodes for AF regardless of packet length,while for DF,when packet length becomes large,the optimal relay moves from close to the source towards the midpoint.