On The Dynamic Channel Resource Allocations In TD-SCDMA System

In 3G mobile communication systems, main services are multimedia data services, of which the traffic is seriously asymmetric between uplink and downlink. With the help of the flexible channel allocation scheme, TD-SCDMA system can support multimedia services very well. Thus the research on channel allocation schemes in TD-SCDMA system has become a hotspot recently. A good channel allocation scheme should fully use the advantages of TDD mode, allocate channels to as many as possible service requests, increase the system capacity, and reduce the system interference as much as possible.In this thesis, Slow Dynamic Channel Allocation (Slow DCA) in TD-SCDMA system is investigated. Timeslot allocation scheme is mainly focused on allocating the proportion of uplink/downlink timeslots according to service requests in a cell, in order to fulfill the service requests better. Considering the effect of the special cross timeslot interference of TDD systems, effort will be made to reduce the cross timeslot interference as much as possible, in order to increase the resource utilization.The Hot-Cell DCA scheme is firstly analyzed and simulated, and the results show its limited performance under some special service scenarios. Based on this result, the conflict between cross timeslot interference and resource unilateral limit is indicated, and an inequation condition to find out the optimal balance point between cross timeslot interference and resource unilateral limit is discussed. According to this inequation, a new improved Hot-Cell scheme is presented, which has better performance over the existing schemes.The Cell-Division scheme using the function of localization of smart antennas, can effectively increase the distance of cross timeslot interference, and reduce the effect of cross timeslots interference. In this thesis, the Cell-Division scheme and the improved Hot-Cell scheme are combined, called Cell-Division Hot-Cell scheme. The new scheme has advantages possessed by both schemes mentioned above, which can further increase the system resource utilization. In practical TD-SCDMA system, a Slow DCA scheme should be adopted according to different factors.