| With the development of mobile communications, mobile users and Internet users are increasing dramatically. People expect that next generation mobile communication systems can provide larger capacity and support mobile multimedia services. Besides providing real-time speech service, next generation mobile communication systems are required to support non real-time services such as low/high rate data, pictures etc. Heterogeneous services have different quality of service (QoS) requirements, for example, the requirements of time delay, error bit rate, and transmission rate for heterogeneous services are differentiated. There are two main objects for wireless network design, one is to guarantee QoS requirements of heterogeneous services, and the other is to make resource utilization maximized. This recurs to radio resource management (RRM). RRM for FDMA/TDMA systems is relatively simple and just needs to assign frequency and time slots properly, while RRM for CDMA systems is much more complex. Code division multiple access is key candidate project of air interface for the third generation mobile communication systems. CDMA system is a self-interfered one, the capacity of which is limited by co-channel interference. It's necessary to assign system resources reasonably. Radio resource management for the third generation mobile communication systems includes call admission control, handoff control, power control, load control and packet scheduling. This dissertation pays attention on call admission control, handoff control, power control and load control for mobile multimedia communication systems. Chapter 2 proposes a resource reservation and handoff queuing-based call admission control policy for multi-services wireless cellular mobile system. In addition to reserve resource for handoff call, different sized buffers are set for handoff calls of real-time and non real-time services respectively, and higher priority is given to handoff call of real-time services. Compared with call admission control with resource reservation, this policy reduces handoff failure probability evidently, while new call's blocking probability is hardly changed.Chapter 3 proposes an adaptive interference threshold-based call admissioncontrol for multimedia CDMA system. Compared with fixed interference threshold-based call admission control, this policy improves the system performance.Chapter 4 proposes a handoff queuing-based call admission control strategy for WCDMA system. Compared with call admission control without handoff queuing, this strategy improves the system performance with lower handoff call blocking probability. Chapter 5 studies soft handoff in multi-service CDMA systems, analyses relationship between system performance and active set add threshold and delete threshold, and gives simulation results accordingly, finally reasonable values for active set add and delete threshold are obtained. Chapter 6 proposes a downlink power control scheme for multi-service CDMA cellular mobile communication system. Optimal power allocation for the system can be considered as getting the maximum real eigenvalue of the normalized link gain matrices with constrained conditions. Compared with power control with fixed transmission power, this scheme reduces call outage probability and interference, thus improves the system capacity. Chapter 7 studies power control for wireless cellular CDMA data communication systems. In allusion to data's non real-time characteristic and retransmission mechanism, a net utility-based power control scheme (which considers price function) is proposed. Compared with utility-based power control (which considers no price function), the former increases mobile's utility, reduces mobile's emission power, and thus extends mobile's session time and improves the system capacity. Chapter 8 studies load control for multi-services CDMA mobile cellular communication systems. Loads are estimated firstly for uplink and downlink separately, and then corresponding call admission control policy is p...
|
PDF Full Text Request