无线环境下保证QoS的传输层拥塞控制机制

A Novel TCP Congestion Control Mechanism for Wireless Network

讨论了在无线信道条件恶化时,如何根据用户的服务质量(QoS)要求降低传输控制协议(TCP)发送速率的最佳参数值,在此基础上给出了2种调节TCP拥塞口的算法.目前在无线环境下的TCP拥塞控制研究一般考虑如何提高吞吐量,出现误码丢包时不减小拥塞窗口的大小,这种设计导致了数据发送可靠性的降低.本方案则同时考虑吞吐量要求和可靠性要求,很好地解决了无线环境下TCP吞吐量和用户的QoS要求.仿真结果证明,该机制有效地保证了用户的QoS要求,又不会过多降低系统吞吐量.

The optimal value of the TCP（transport control protocal） data sending rate was studied when the wireless channel was in bad state. Two algorithms to adjust the size of TCP CWND（congestion window） were presented. The target of most research on TCP in wireless network is to improve the throughput. So the size of CWND doesn＇t decrease when the packet loss is due to corruption. The result is the decrease of the reliability of TCP when the heavy packet loss rate occurs. The requirement of throughput and reliability were studied. The simulation results demonstrate that the QoS（quality of service） requirement is met and the throughput is not declining greatly.