无线衰落信道中RLP性能分析

Analysis of RLP Performance over Wireless Fading Channel

在考虑无线衰落信道中突发差错引起的分组丢失的情况下 ,采用一阶两状态 Markov模型 ,推导出了无线链路层 (RL P)当 ARQ最大允许重传次数 Nr有限时的吞吐量效率公式 .结果表明 ,对于 Go- Back- N协议 ,当帧差错率较小时 ,重传次数 Nr对吞吐量效率的影响非常小 ;当帧差错率变大时 ,存在“地板效应”.进一步研究表明 ,无线链路中当最大允许重传次数增大时 ,在 RLP的吞吐量效率减小的同时 ,由 RL P提交给 TCP的剩余帧差错率也减小了 .

Considering the packets loss caused by burst errors over wireless fading channel, RLP performance is analyzed using the first order two state Markov model. The formula to calculate the RLP throughput efficiency is also deduced while the maximal numbers of allowed retransmission is limited. Results show that when FER is small, the RLP throughput efficiency hardly decrease as the retransmission numbers increasing, and when FER is large, there exists a 'floor effect' in RLP throughput efficiency for Go Back N. Further study shows that the RLP throughput efficiency decreases when the numbers of allowed retransmission increase, meanwhile the residual FER, which is reported to TCP by RLP, is reduced.