Optimal access control for integrated services wireless networks

The requirement of ubiquitous information access motivates the development of wireless communication networks. Such networks are expected to support m ultimedia applications with different traffic characteristics and quality o f service (QoS) requirements, similar to wired networks. Hence, in the case of wireless networks it is also important to devise effective resource all ocation policies to guarantee a given QoS to different traffic classes. To increase frequencies reuse, a current trend in wireless cellular networks i s toward microcellular architectures; this increases handoffs rates, with t he possible consequent increase in the probability of connection interrupti ons. Hence, an important measure of the effectiveness of access control pol icies for wireless networks is the blocking probability of arriving connect ion requests in each cell. We consider the problem of optimal access contro l for a wireless network supporting multiple classes of traffic. In particu lar, we consider two optimization problems: minimizing any linear function of the blocking probabilities of different classes, and minimizing the bloc king probability of one class, with a constraint on the blocking probabilit y of the other class. For the first problem, we prove that the search for t he optimal control policy can be limited to policies that base their decisi ons only on the occupancy levels. This result also implies that hysteresis- based policies are not optimal. For the second problem, we prove that withi n the class of fixed threshold policies a fractional threshold policy is op timal and provide a simple algorithm to calculate this threshold given the system parameters. (C) 1998 Elsevier Science B.V. All rights reserved.