基于分布式PEP的卫星网络TCP性能增强协议

提出了一个基于分布式性能增强代理的卫星网络专有通信协议：XP协议，用于解决卫星网络环境中因长时延、高误码率和非对称信道带宽等因素所导致的TCP传输性能低下问题．协议的设计考虑到了与地面链路上TCP连接的接口关系和多连接共享同一卫星信道时的带宽分配问题．主要贡献包括两路半握手连接建立机制，速率控制和基于测量的动态带宽分配算法，以及基于发送方主动请求的延迟确认技术等．仿真和真实环境实验表明，分布式性能增强代理和XP协议的使用可显著提高网络中下行卫星链路的吞吐量，多数情况下带宽资源利用率可提高至85％以上，且在多连接共享带宽的情况下能够保持较好的公平性．

A Distributed PEP-Based TCP Performance Enhancing Protocol for Satellite Networks

Based on distributed performance enhancing proxies, a new transport protocol for the satellite environment, the XP protocol is presented. It is designed and optimized to overcome the performance degradation that TCP experiences in satellite networks due to their long latency, high bit error rate, and bandwidth asymmetry characteristics. Main contributions include a reliable two-and-half-way handshake connection establishment mechanism, rate control and a measurement-based adaptive bandwidth allocation algorithm, and a delayed acknowledgements technique based on active sender-request. Interactions with the TCP connections in terrestrial segments are also considered. Emulation and real operating environment experiments show that the throughputs achieved by XP improve substantially in comparison with the regular TCP, and the fairness is also maintained perfectively when the bandwidth is shared among multi-connections.