A heuristic algorithm for channel allocation of multi-rate data in hybrid TDMA/FDMA digital cellular systems

In a hybrid TDMA/FDMA digital communication system such as the GSM system, Global System for Mobile communications, a channel is defined by a tuple consisting of frequency band number and slot number. For a normal voice connection, an idle time slot will be assigned upon a channel request in uplink direction and correspondingly one for downlink direction. For multimedia applications with multi-rate connections, multiple slots are to be assigned. The problem of how to assign the slots efficiently arises if the slots can be chosen from different frequency bands. In the study presented here, a heuristic channel assignment algorithm is proposed under the assumption that a mobile unit can simultaneously transmit data through multiple frequency bands. The goal is to keep the number of frequencies used small in each connection so as to keep the intercell interference low. The proposed algorithm, having an inference property, is based on the binary clustering of idle time slots to speed up the channel assignment process. The proposed algorithm is compared to a locally optimal algorithm by simulation and is shown to be more time efficient with minimal tradeoff