Call admission and handoff management in wireless broadband communication systems

Abstract

In this dissertation, we are concerned with the issues on call admission and handoff control for supporting multimedia services in wireless broadband communication systems. First, we derive call admission criteria for constant bit rate multi-class services in direct sequence CDMA (DS-CDMA) systems. The call admission criteria are expressed by inequalities to which the number of accepted calls of each class should conform. Those inequalities are necessary and sufficient conditions satisfying the requirement of the bit energy-to-interference power spectral density ratio. The optimal received power is derived to cause the least interference to other signals while maintaining the acceptable bit energy-to-interference power spectral density ratio. The call admission criteria also represent the capacities. It is shown that if the maximally receivable power of a call of each class is identical in the multi-code system and the single-code system using a variable processing gain, the capacities of both systems are also identical in nonfading channels. However, in multi-path fading channels, the multi-code system is shown to be better than the single-code system in terms of capacity. Capacity is also derived in a dynamic multiple cell environment. Second, we derive call admission criteria for multi-class on/off traffic in DS-CDMA systems. For this purpose, given the requirements of bit energy-to-interference power spectral density ratios and outage probabilities, we obtain a set of all admissible points satisfying those requirements. Whether a point, denoting the number of calls for each class, is admissible or not is determined by numerically solving the nonlinear equations representing the service quality requirements. Finally, we propose a fast handoff management scheme using permanent virtual connections (PVCs) reserved between neighboring base stations (BSs) in asynchronous transfer mode (ATM)-based mobile networks. In the proposed scheme, the handoff can be quic...