Application Performance in Ka-band

Although the new generation of Ka-band systems is built to support higher bandwidth at lower cost, there is still some problem associated with latency, the half-second delay created when signals travel to and from the satellite. Various acceleration technologies mitigate the impact of that delay on protocols and some applications, but for anything that depends on real-time communications, particularly voice and Internet gaming, the satellite delay will be noticeable. The only way to know how applications will perform under high latency conditions is to test them.

Ka-band Research

A team at the Center for Satellite & Hybrid Communication Networks, a NASA-funded organization within the University of Maryland's Institute for Systems Research, is performing modeling and simulation studies on power allocation in multiple spot beam satellite communication systems. One of the team's objectives is to identify ways to optimize network performance and traffic aspects of the network. The team found that for some users in deep fade periods, full recovery is not possible within reasonable session times even if a forward error correction code capable of generating many encoding packets is used. It is better for the transport protocol to drop the connection to these users rather than wasting system resources with multiple connection attempts. The focus, in a follow-up work, was on how a reliable channel condition value can be obtained for a spot beam without asking or collecting periodic feedback from every active user, as this would place a heavy burden on the limited or scarce network resources in the return path, either a satellite return channel or a terrestrial dial-up return channel.

Testing and Ka-band Quality of Service

Testing live satellite links in order to troubleshoot problems and optimize performance is time-consuming and expensive, whereas simulators offer a simple and efficient alternative way to test systems in the lab under a variety of conditions. To insure the best QOS It is critical to test the whole end-to-end network. Testing individual sections may not show important interactions between the component links.