Study On The Slow Dynamic Channel Allocation Technology In TD-SCDMA System

The TD-SCDMA Mobile Communication System as the first Chinese self-owned intellectual property rights International Telecom Standard. It adopts smart antenna, joint detection and synchronous CDMA and other advanced technologies which gives the system higher performance and frequency utilization efficiency. By using these advanced technologies, we solves various problems. It received a universal attention in the international organization. TD-SCDMA as a mobile system which has the characteristic of CDMA, has a reliable and efficient radio resource management to guarantee its performance and capacity. Compared with FDD system, it adopts smart antenna, multi-detection, synchronous and special frame structure in physical layer. It needs not only a maximum enhancement of system resource utilization, but also a harmonization of all kinds of resources. There are various radio resources of TD-SCDMA system including code, frequency, timeslot, power and space. So the complicated radio resource management strategy and the dynamic channel assignment algorithms are important. The TD-SCDMA systems can flexible adapt its up/down link switching point according to different traffic proportion. It brings a big challenge to dynamic channel assignment algorithms.Usually the DCA can be divided into Slow-DCA and Fast-DCA.The Slow-DCA scheme is used to allocate and adjust radio resource for every cell in order to confirm the proportion between uplink (UL) and downlink (DL).The Fast-DCA scheme is used to allocate radio resource for the user applying for connection and adjust the resource based on system state.In this paper, we systematic discuss the dynamic channel assignment algorithms base on the TD-SCDMA system radio resource management strategy. Firstly, by using theoretical calculation, we get SNR and the capacity of the cell both in the two-cell model and the multi-cell model. We put the results into simulation. Since proportion between the time slots and portfolio matches is almost the same, the capability losing costed by the limited of unilateralism resource is less and the service transmission adaptability will be better, the proportion of time slots in UL/DL and the switching point can be confirmed. At the same time, because of different condition of the cell, we need to distinguish the cell which is under heavy traffic from the cell which is under little traffic. The cell which is under heavy traffic need to ensure QoS and should consider firstly. In this paper ,we use the theoretical calculation, which is both in the two-cell model and the multi-cell model, to improve an algorithm which is suit for TD-SCDMA system. The algorithm's aim is to max the capacity of the system by considering the cell which is under heavy traffic firstly.In this paper, we use computer to simulate the Slow DCA algorithm. Compare it with the former algorithm, the result shows that the improved algorithm is more suitable for the system than the former algorithm, because the capacity of time slot is got by theoretical calculation. Compare the improved algorithm with the algorithm which does not use crossd time slot, we find that the improved algorithm is better than the non-crossed-time-slot algorithm in the performance. The improved algorithm the capacity of the cell, ensure the QoS and better the performance. Especially when it applies to the heavy-traffic cell, the improved algorithm can increase the capacity by 27 percent. It shows that the improved algorithm is effective.Certainly the results of this paper are provided for the further research on the DCA of TD-SCDMA.