Automatic and adaptive slot allocation method for initial ranging contention process

In this paper, we present a method to optimally manage the access slots for the initial ranging contention process in IEEE802.16e air interface. In conventional method, the number of the initial access slot is fixed to a large number in common circumstance. The reason using the static large slot is to reduce the initial access collisions by slot contentions of the mobile terminals. Therefore the usage rate of the initial ranging slot may be lower in the normal mobile access demands. Furthermore future mobile access demands can be changed to more or to less. Therefore the maintenance cost will be increased to rearrange the initial ranging slots. In these regards, we develop an automatic and adaptive slot allocation method for the initial ranging contention process. The method uses simply measureable two system parameters, and we develop a simple algorithm that can automatically track the current optimal slot numbers. In simulation results, we show that the method finds the optimal slot numbers in terms of optimal mobile access delay and slot usage rate. From the results, it is also considered that this method can provide an automatic process for the initial mobile access process of any cellular networks.