基于广义误码率的MANET流媒体传输端到端速率控制理论和方法

Generalized BER Based Theory and Methodology of End-to-End Rate Control for MANET Streaming Media Transmission

针对移动自组织网络(Mobile Ad hoc Networks,MANET)的特点和IEEE802．11的链路层重传机制和分包策略的不足,研究基于广义误码率(Generalized Bit Error Ratio,GBER)和参考无线包重传概率(Packet Retrans- mission Ratio,PRR)的时延约束方程理论和传输层包长调整方法,并设计基于时延约束的MANET流媒体传输可变包长TCP友好速率控制机制(Variable Packet size TCP-Friendly Rate Control,VPTFRC)．与其他方案不同,该机制进一步考虑了无线包重传概率对于包长调整和TCP友好速率控制机制的影响,给出了这一机制的理论模型与相关计算的详细说明,仿真试验的结果验证了该方法在有效吞吐量、传输延时及抖动和TCP友好性方面优于TFRC协议．

In consideration of features of MANET（Mobile Ad hoc Networks） and shortages of retransmission and packet fragment strategies in link layer based on IEEE 802.11, this paper researches on the theory of delay-constrained equation and the policy of packet-size adjustment in transport layer according to Generalized Bit Error Ratio（GBER） and wireless Packet Retransmission Ratio（PRR）. A Variable Packet size TCP-Friendly Rate Control （VPTFRC） scheme for streaming media transmission over MANET based on the theory is proposed. Unlike other proposals, this mechanism takes the impact of wireless PRR on the packet-size adjustment and TFRC performance into consideration. The theoretical model and relevant detailed deduction are also presented. Simulation results demonstrate the proposed mechanism can simultaneously achieve higher goodput, better TCP fairness, shorter transmission delay and less jitter than TFRC protocol.