Random access delay performance of TETRA professional mobile radio system

Random access delay performance of TETRA professional mobile radio system is studied in this research. Based on Markov chain and queue theory models, the impact of random access frame length and waiting time on signaling delay in TETRA air interface protocol is analyzed. Numerical results show that, under heavy traffic load condition, the short access frame length or waiting time, which results in the high probability of collision when signaling is retransmitted, is the main reason of generating delay; while under light traffic load condition, the long access frame length or waiting time, which results in the long waiting time before signaling is retransmitted, is the main reason of generating delay. The maximum number of users which can be served by TETRA system under one base station (BS) is achieved through parameter optimization, which provides a basis for system capacity planning.