Research On Downlink Resource Allocation In Wireless Network

In recent years, wireless mobile communication is developing fleetly and wireless mobile users are growing rapidly. Wireless mobile communication system is required to provide more data, image, video and other multimedia information for users. These requirements lead more wireless resources occupied. The conflicts between Quality of Service and scarce resources let what kind of approach should be made to allocate limited wireless resources efficiently and support more users and a variety of businesses become an important research topic. This paper targets at both CDMA2000-1xEV-DO system and multi-user OFDM system to study the allocation of wireless resources.For enhancing system performance, we develop an efficient predictive scheduling algorithm namely predictive scheduling of using channel states information (PSUCS) and define channel model by using multi-state Markov model in CDMA2000-1xEV-DO system. According to use the current channel state information, PSUCS predicts the next time slot channel state information; resource scheduling is described as the largest utility function optimization model and the optimal scheduling strategy. The key feature of PSUCS is that with the purpose of maximizing the system utility function, at the time of scheduling, PSUCS not only uses the current channel state information but also uses the next time slot channel state information to get the effective wireless resources allocation. Results of simulations are given to demonstrate that the proposed algorithm can give considerable throughput gains without compromising fairness.In multi-user OFDM system, according to the OFDM multi-carrier transmission characteristics and the multi-user features of wireless communication system, we use cross-layer and develop an algorithm namely cross-layer scheduling and approximate maximize the objective function algorithm (CAMOF) which can be used in OFDM system downlink scheduling. The resource allocation algorithm considers the channel state information and power constraints in physical layer, it also considers the scheduling strategy in data link layer. We design update module in data link layer and in each schedule period we can get the control parameters according to feedback from the physical layer and user's weight in former schedule period. We adjust each user's weight dynamically according to control parameters and user's average rate in former schedule period. Experimental results show that the algorithm can get better performance in objective function value, user's average rate and fairness. It is an effective algorithm in allocation of sub carriers, bite and power.