受物理层参数影响的RLP协议性能研究

Study on RLP Protocol's Performance Effected by Physical Layer's Parameters

给出了无线衰落信道的一阶Markov模型中模型参数计算方法的推导,并采用该模型,研究了物理层参数对Go-Back-N协议性能的影响.结果表明,对于Go-Back-N协议,当信道衰落余量较小时,重传次数Nr对吞吐量效率的影响非常小;当信道衰落余量变大时,吞吐量效率对重传次数的变化不明显.同时,衰落余量增大,向上层提交的剩余帧差错率减小,协议流量增大;而当最大允许重传次数增大时,在减小提供给TCP层的差错率的同时,协议本身性能要降低.

The calculating method of the first Order Markov model's parameters in Wireless fading channel is deducted. By the way of which, we study the effects of the parameters of the physical layer on the performances of Go-Back-N Protocol. It's shown that more larger the correlation between adjacent packets gets, more larger the throughput of RLP is. And for Go-Back-N Protocol, when the fading margin of the channel is small, the effect of the number of repeating transmission on the throughput efficient is trivial; when the fading margin become larger, the changing of the throughput efficiency is not obvious. Meanwhile, when the fading margin gets larger, the left frame error rate provided to upper layer is reduced, and the throughput of the protocol even get larger; while when the greatest admissible retransmission value gets larger, the error rates provided to the TCP layer get small, concurrently the performance of the protocol itself is destroyed.