EFFICIENT TIME-SLOT ASSIGNMENT ALGORITHMS FOR SS TDMA SYSTEMS WITH VARIABLE-BANDWIDTH BEAMS/

In this paper, we present efficient sequential and parallel algorithms for computation of time-slot assignments in SS/TDMA (satellite-switch ed/time-division multiple-access) systems with variable-bandwidth beam s. These algorithms are based on modeling the time-slot assignment(TSA ) problem as a network-flow problem. Our sequential algorithm, in gene ral, has a better time-complexity than a previous algorithm due to Gop al, et al. [4] and generates fewer switching matrices. If M (N) is the number of uplink (downlink) beams, L is the length of any optimal TSA , and alpha is the maximum bandwidth of an uplink or downlink beam, ou r sequential algorithm takes O((M + N)3 min(MNalpha,L)) time to comput e an optimal TSA when the traffic-handling capacity of the satellite i s of the same order as the total bandwidth of the links. Our parallel algorithm uses L/2 processors and has a time-complexity of O((M + N)3 log L) on a PR AM model of parallel computation. We then generalize th is algorithm to P less-than-or-equal-to L/2 processors and describe an efficient implementation of the algorithm on a hypercube multiprocess or with P processors. A massively-parallel version of the algorithm ru ns in O((M+N)2 log(M+N)logL) time on (M+N)L/2 processors.