Time-slot management in digital portable radio systems

The problem of assigning a time slot to a user in a frequency-reuse time-division multiplexed digital portable radio system is considered. Time-slot assignment algorithms are studied using a discrete-event stochastic computer simulation that models many concurrent two-way radio links. Three time-slot assignment algorithms were modeled: random selection of an idle time slot, selection of the idle time slot with the least interference power, and selection of the idle time slot with the largest signal-to-interference ratio not exceeding a given threshold. It is shown that under heavy traffic loads, measurement-based assignment of time slots yields improvements in transmission quality of 8 dB (local mean) to 15 dB (instantaneous) over random assignment for 99% of the users. As a result, the amount of radio spectrum needed is halved according to local mean performance.<>