An Adaptive Random Access Protocol for OFDMA System

A random access protocol, particularly suitable for OFDMA system, is proposed and analyzed in this paper. The protocol adopts a new dynamic RACH assignment algorithm and a new adaptive access probability scheme. Under the condition of light load, Base Station (BS) will adjust the number of RACHs to improve the channel utilization. Under the condition of heavy load, BS will take effective measure to guarantee QoS requirements of high priority traffics. In addition, the article introduces a statistical model to estimate system load, which is one of the features of the protocol. The simulation results fully indicate that the proposed random access protocol is efficient and reliable at conditions of both high and low load, and not only provides excellent transmission quality guarantee for higher priority traffics, but also supports lower priority traffics transmission efficiently in the integration traffic environment.