应用层和信道质量信息辅助的延时应答算法

Application and channel quality delayed-ACK algorithm

为降低应答信号开销，IEEE802．15．3高速个域网引入了延时应答机制。为解决个域网延时应答因无法适应视频业务的变速率特性和无线链路的不稳定性，并会严重降低视频业务性能，在针对视频应用分别分析立即应答和固定突发MAC帧数延时应答策略的基础上，利用视频帧尺寸信息和无线信道质量信息对延时应答策略进行优化，提出了一种应用层和信道质量信息辅助的自适应延时应答算法。仿真结果表明：该算法在不同负载及信道情况下较立即应答策略和固定突发MAC帧数延时应答策略明显改善视频业务服务质量，可提高视频业务的可解帧率性能约2％～4％。

The delayed-ACK （Dly-ACK） scheme is used in IEEE 802. 15.3 high-rate WPANs to reduce ACK overhead. For high variable bit rate and delay sensitive video-dominated scenarios in wireless personal area networks （WPANS）, immediate acknowledge （Imm-ACK） and fixed delayed acknowledge （Dly-ACK） will significantly degrade the quality of service （QoS） since they are not appropriates for variable bit rate video streams and wireless channel instabilities. Analyses of Imm-ACK and fixed Dly-ACK schemes for video streaming over IEEE 802. 15.3 WPANs led to an application and channel quality aware adaptive Dly-ACK algorithm for video streaming over 802. 15. 3 WPANs, which includes a frame size and error-rate-based dynamic Dly-ACK burst size adjusting algorithm. Extensive simulations were carried out to evaluate the algorithm. The results show that the algorithm consistently outperforms both Imm-ACK and fixed Dly-ACK schemes for all simulated load levels and channel conditions in terms of the fraction of decodable video frames at 2%-4%.