QoS Guaranteed Call Admission Control In Multimedia Wireless Networks

Rapid progress of mobile communication and Internet networks in recent years has seen a dramatically growing demand for wireless multimedia services which require reliable and high-speed data transmission over a wireless channel. One of the most challenges for the next generation wireless communication systems is to support a large number of subscribers and to ensure the fulfillment of quality-of-service (QoS) requirements. How to support the different QoS requirements of heterogeneous services and utilize the scarce wireless resource efficiently in the situation of error-prone wireless channel get more attention in recent years. Call admission control (CAC) is one of the most important parts of resource management in wireless cellular networks, and an efficient CAC scheme is essential to provide QoS guarantee of different services to as many users as possible. It keeps the system work stable through accepting or rejecting users' service requests. CAC solves the conflict between the service satisfaction of user and system resource utilization.In chapter 1, we give the research background and the signification of the study. Then, the radio resource management for CDMA system especially the CAC technology in wireless networks is introduced in chapter 2, and a particular presentation of the system evaluation model for wireless multimedia networks which is used in this thesis is also delivered.Based on the traffic model we introduced in chapter 2, a novel call admission control algorithm for the WCDMA network is proposed, which uses the load factor of the up-link as the main admission criteria. It doesn't only take into account the different priorities of different services, but also the different priorities between a new call and a handoff call. The threshold of the algorithm is also dynamic. The simulation results indicate that the algorithm can minimize the dropping rates of all handoff calls and blocking rate of the new voice calls, meanwhile, the blocking rate of the non-real-time data service can also be kept on the relative low level.In mobile cellular systems, forced termination of a call in progress in the target cell is less desirable than blocking a new call attempt. The usual CAC algorithms often give handoff calls higher priority and assign a part of resources particular for these calls .The mechanism of the reservation of resources only for handoff calls sometimes may results in the poor utilization of the resource in system. In chapter 4 of this thesis, the location of an existed call is estimated based on the measured pilot signal strengths by this mobile station (MS) from a number of nearby base stations (BSs), so the target BS of this call can be predicted to intentionally and efficiently reserve resource, the amount of reserved resource will also be dynamic. The simulation results show that this policy can guarantee the QoS of handoff calls efficiently, and also improve the resource utility significantly.Finally, the thesis is summarized and the future work is brought forth.