面向空间通信的DTN一体化传输性能约束研究

Research on DTN integrated transmission performance constraints for spatial communication

相比于地面网络,空间通信链路具有较长的延迟、频繁的中断、较高的误码率及上下行链路非对称等特性,互联网成熟的网络技术并不适用,对网络可靠传输性能的保障提出了挑战。不同于空间IP协议体系方案,针对空间通信链路特性,采用多种传输机制兼容的DTN(delay tolerant networking)协议架构。重点针对链路非对称、和信道误码率等特性,研究对保障可靠传输的TCP和LTP两种传输机制的性能制约,并给出LTP(Licklider transport protocol)机制的跨层包尺寸优化模型。基于半实物仿真平台,构建静止轨道GEO以下的空间通信场景,进行真实数据流仿真,分析链路因素对协议传输性能的影响。仿真结果表明,在近地端误码率和信道非对称比例较小的空间通信场景中,仍可以采用TCP机制保障可靠传输,但对于误码率和信道非对称比例较高的通信场景,应考虑采用LTP传输机制保障通信的有效性和可靠性。

Compared with the terrestrial network,the spatial communication link has the characteristics of long delay,frequent interruption,high bit error rate,and asymmetric uplink and downlink.The mature network technology of the internet is not suitable,which challenges the guarantee of reliable transmission performance of network.Different from the scheme of spatial IP protocol system,DTN(delay tolerant networking)protocol architecture compatible with various transmission mechanisms according to the spatial communication link characteristics was adopted.Focusing on the link asymmetry and channel error rate,the performance constraints of TCP and LTP(Licklider transport protocol)transmission mechanisms to ensure reliable transmission were studied,and the cross layer packet size optimization model of LTP mechanism was given.Based on the hardware in the loop simulation platform,the space communication scenario below GEO was constructed,and the real data flow simulation was carried out to analyze the impact of link factors on the transmission performance of the protocol.The simulation results show that TCP mechanism can still be used to ensure reliable transmission in the space communication scenario with low bit error rate and channel asymmetry,but LTP transmission mechanism should be considered to ensure the effectiveness and reliability of communication in the communication scenario with high bit error rate and channel asymmetry.