An adaptive time slot assignment algorithm for variable bandwidth switching systems

Abstract

In this paper, we consider an optimal (i.e., minimum scheduling length) time slot assignment (for short, TSA) problem in variable bandwidth switching systems. In previous studies, the interdependencies between two consecutive switching configurations were neglected. However, it is highly probable that the amount of change between the switching configurations will be small. Therefore, it is unnecessary to schedule all traffic for each configuration if we preserve the previous switching configuration and update the switching configuration appropriately according to changes in traffic demand. The adaptive TSA algorithm proposed in this paper employs such an idea and reduces the computational burden of finding switching configurations. The computational complexity of the proposed algorithm and simulation results are reported. The results show that our algorithm is more efficient than existing optimal TSA algorithms. Scope and purpose In a satellite-switched time division multiple access (SS/TDMA) system, the satellite has a number of spot beam antennas covering geographically distributed zones and a solid-state RF switch to provide connections between the various uplink and downlink beams with different bandwidths depending on traffic rates of corresponding covering zones. A TDMA frame is divided into several time slots, and each slot has a switching configuration permitting a certain amount of traffic to be transmitted. The objective of the system is to ensure that all traffic in a given traffic matrix can be transmitted without conflict within the TDMA frame and to accomplish this with maximum transponder utilization. (C) 2000 Elsevier Science Ltd. All rights reserved.