Call Admission Control In Wireless Heterogeneous Networks

With the rapid development of wireless access technologies, various Radio Access Technologies (RATs) are emerging and many kinds of access networks coexist. However, different access technologies are not well compatible with each other, it is so difficult to inter-communicate between different systems that networks become isolated with each other. The purpose of integration of heterogeneous wireless networks is to achieve the coordination of various wireless access capabilities, so as to provide users with more and high-quality service experience. Joint Radio Resource Management (Joint Radio Resource Management, JRRM) is implemented to achieve rational allocation of radio resources and ensure the transmission quality of wireless services. With characteristics of different RATs complement each other, JRRM can be used properly to obtain enhancement of all network utility. Call Admission Control (CAC, Call Admission Control) is one of the key RRM strategies. It is implemented to reduce network congestion, meanwhile ensure the quality of service (QoS) and enhance the utilization of network resources.Based on previous studies on admission control in heterogeneous wireless networks, some creative contributions are proposed in this dissertation, mainly including the following aspects. Firstly, a DiffServ-based joint admission control scheme is proposed, which takes resource reservation into consideration. For this scheme, it is mainly applied in a specific scenario where UMTS networks are integrated with WLAN. Secondly, a joint admission control is proposed based on a novel QoE (Quality of Experience) description model. Since QoE is a concept of both objective and subjective, the QoE is decomposed into several KQI dimensions in the model. Meanwhile, each KQI dimension is valued by several KPI parameters. The proposed scheme overcomes the drawback of AHP algorithm and considerable system gain can be obtained. Furthermore, in order to give the proof of "multi-access advantage", throughput of link-level in multi-access systems are derived. According to different number of radio accesses, two types of multi-access transmission can be defined which is called Switched Transmit Diversity (Switched MRTD) and Parallel Transmission Diversity (Parallel MRTD), respectively. The two types of MRTDs are researched in a comparative way.