Random Access Delay Optimization of PDT Digital Trunking System

Random access delay optimization of PDT digital trunking system is mainly studied by the methods of rolling access frame 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 PDT protocol is analyzed. The results show that under light traffic load condition, the long waiting time caused by long access frame length or waiting time before signaling is retransmitted, is the main reason of generating delay; while under heavy traffic load condition, the high probability of collision which short access frame length or waiting time leads to when signaling is retransmitted, is the main reason of generating delay. The maximum number of users which system supports at given maximum accessing time can be achieved through parameter optimization, which provides the basis for system applications.