Research On Packet Scheduling Technique In TD-HSDPA

TD-HSDPA which stands for high speed downlink packet access in TD-SCDMA is an enhanced technique of the 3rd generation mobile communication standard. The purpose of introducing this technique is facing the increasing data communication service and strengthening the competition of the standard. For achieving high data rate communication, besides the improved architecture and techniques such as AMC and HARQ, the packet scheduling technique plays a very important role. It controls the allocation of the system resource and determines the system behavior.First, the dissertation analyses the elements related to the packet scheduling in HSDPA system, and summarizes the similarities and differences of these elements in the TD-HSDPA and W-HSDPA. The highest rate that could be achieved in multi-carrier TD-HSDPA is deduced and furthermore the spectrum efficiency advantage of TD-HSDPA compared to W-HSDPA is proved. Then the rationality and validity of scheduling based on the CQI parameter is deduced and proved by mobile fading channel theory. The threshold rate in theory of invalid scheduling is deduced and a scheduling model is proposed. The dissertation mainly studies the scheduling algorithms which support the non-real time service, and the analysis and simulation results prove that PF algorithm gets the balance of fairness and throughput. The PF algorithm is better than the RR and Max C/I algorithms. A modified algorithm is proposed based on the classical PF algorithm according to the unfairness made by the new user and the theoretical analysis and simulation results prove the modified algorithm improves the fairness of the users, and at the same time the performance of the system throughput has improved. At last, the principles of the selection about the time window in PF algorithm are discussed and two schemes are proposed for the implementation of the packet scheduling algorithms.