Satellite communications networks with IP quality of services

This paper presents a satellite communications (SATCOM) architecture that uses packet switched technologies and addresses the relationships between SATCOM and IP quality of service (QoS). The onboard satellite processing with fast-packet switching rather than traditional circuit switch or bent pipe SATCOM connections, is described first. The performance of such an architecture may improve or degrade with IP QoS services depending on how they interact. The network architecture incorporates a bandwidth-on-demand concept through demand-assigned multiple-access (DAMA) protocols, and achieves multiple levels of QoS services through IP class-of-service (CoS). This concept improves application performance, increases network utilization and throughput, and reduces message/file transfer times. The bit error rates that are inherent to SATCOM networks do not apply directly to the architecture. Underlying performance evaluation methodologies as well as related implementation issues for the proposed architecture are addressed. The onboard switching architecture generally brings about performance improvements, but one case that degrades performance is presented. In this example, excessive delays occur when transmitting moderate-to-high bit error rates due to an IP error recovery procedure that induces more lower-layer packet segmentation and reassembly processes. Thus, the higher bit error rate caused by satellite links can be critical for the performance. This observation along with related protocol and performance issues leads to the conclusion that the essential IP features will only be operative for the fast-packet switching SATCOM architecture.