A Multiple Subset Sum Formulation for Feedback Implosion Suppression over Satellite Networks
Gun Akkor, John S. Baras and Michael Hadjitheodosiou
Number: CSHCN TR 2004-21, Year: 2004, Advisor: John S. Baras
In this paper, we present a feedback implosion suppression (FIS) algorithm that reduces the volume of feedback information transmitted through the network without relying on any collaboration between users, or on any infrastructure other than the satellite network. Next generation satellite systems that utilize the Ka frequency band are likely to rely on various fade mitigation (compensation) techniques ranging from adaptive coding to dynamic power control, in order to guarantee a service quality that is comparable to other broadband technologies. User feedback would be a valuable input for a number of such components, however, collecting periodic feedback from a large number of users would result in the well-known feedback implosion problem. Feedback implosion is identified as a major problem when a large number of users try to transmit their feedback messages through the network, holding up a significant portion of the uplink resources and clogging the shared uplink medium. In this paper, we look at a system where uplink channel access is organized in time-slots. The goal of the FIS algorithm is to reduce the number of uplink time-slots hold up for the purpose of feedback transmission. Our analysis show that the FIS algorithm effectively suppresses the feedback messages of 95% of all active users, but still achieves acceptable performance results when the ratio of available time-slots to number of users is equal to or higher than 5%.