Investigation On Call Admission Control In Wireless Multimedia Networks

The number of users is increasing quickly in mobile communication system, and the traffic types become diverse and the service of quality (QoS) requirement needs to be enhanced in recent years. So how to efficiently manage and use the wireless resource is one of the most important problems for the service providers. 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 is now challenging both 3rd generation mobile communication systems and future personal communication systems. Recently, as the most important part of radio resource management, call admission control (CAC) gets more attention.In this thesis, call admission control policies in wireless multimedia communication networks are proposed based on QoS requirements.According to 3rd Generation Partnership Project (3GPP) specifications, a more realistic modeled traffic is taken into account firstly. Based on this traffic model, a residual capacity based call admission control policy is proposed. The priorities according to the traffic characteristics and QoS requirements are defined. The basic idea of our scheme is assigning higher priority classes privilege over lower priority classes in the CAC decision process. Traffic with different priorities has different admission principle, and the QoS requirements are guaranteed efficentlly.As there are more and more asymmetric traffic emerging in the wireless network, the resource should be assigned fairly and reasonably. On the other hand, the operators will define the traffic QoS according to their requirements, and provide the traffic with different QoS guarantee. So in this thesis, a novel QoS based CAC policy for the asymmetric traffic in symmetrical CDMA system is proposed. The basic idea of this method is that: the operators define the priority and QoS according to their requirements. In order to improve the resource utilization, some assigned but not used resource is distributed dynamically to the traffic with lower priority. Call admission control is executed according to the residual capacity and the priority and QoS of traffic. The simulation results show that this policy can guarantee the QoS of different traffic efficiently, and improve the resource utility significantly.In some exiting CAC policies, perfect power control is assumed. But inpractical CDMA systems, the received power is usually hard to be maintained at fixed level because of signal fading and path loss. Especially the transmission of multimedia traffic makes the situation be more complicated. Therefore CAC with imperfect power control for multimedia traffic will be more significant. In this thesis, the system capacity with imperfect power control and other-cell interference factor is analyzed. And then a QoS based CAC policy is proposed. The simulation results show that the system capacity is affected by imperfect power control obviously, and this policy can guarantee the QoS for different traffic efficiently.