Study On Dynamic Channel Allocation Algorithm In TD-SCDMA System

Dynamic Channel Allocation (DCA), one of the key technologies of TD-SCDMA, has the advantages of suppressing the interference, minimizing the channel reuse distance, and thus, utilizes the finite radio resource with greater efficiency and improves the capacity of the system. Using DCA is the superiority of TDD system. First the article introduces DCA and the problem DCA needs to overcome briefly, and then DCA algorithms suitable for TD-CDMA system are proposed.Usually DCA is divided into Slow-DCA and Fast-DCA. The Hot-Cell Slow-DCA is firstly analyzed and simulated, and the results show the limited performance of the algorithm. With Two-Cell model, we study the reason of the poor performance theoretically. On the base of the formula of average resource utilization ratio, the maximal average resource utilization ratio Slow-DCA is brought forward. This method which aims to achieve the maximal average resource utilization ratio as well as the biggest capacity of the cell with heavy load can alleviate the problem caused by the asymmetrical service. Then we propose a feasible scheme of this Slow-DCA which needs less computation. The scheme is shown to result in better average resource utilization ratio in simulation. Further more, a simplified version of the scheme is put forward. With the help of the simulation, we study the performance of the simplified scheme.In the Fast-DCA aspect, we analyze the Fast-DCA based on path loss. We derive an expression of restrictive condition of the capacity in terms of Normalized Signal to Noise Ratio. And then two improved algorithm which are proved to be effective by simulation are proposed. Finally we work over how the smart antenna affect the Fast-DCA.