The Study Of The Channel Allocation Technology In Dynamic Spectrum Access System

The issue of spectrum resources shortage is becoming increasingly serious as the rapid development of wireless communications technology in the world. The utilization of spectrum resources is highly unbalanced in traditional Static spectrum policy of "fragmentation". Dynamic Spectrum Access technology is a great solution to the shortage of spectrum resources issue, which involves heterogeneous wireless system and the Dynamic Spectrum Management policy to provide sufficient bandwidth for mobile user with the premise of ensuring communication for licensed users.The cognitive users use spectrum sensing,spectrum analysis and decision,spectrum allocation to finish the spectrum sharing in Dynamic Spectrum Access system, which means, these three are the key technology in Dynamic Spectrum Access. This thesis analyzed four classic channel assignment model including Graph coloring model,Interference temperature model,Game theory model and Auction bidding model and introduces associate researches.Aimed on the Graph Coloring model, we analyzed the associated channel assignment algorithm from two perspectives: Throughput and Fairness, including the GA and MSB algorithm based on the throughput; DFA and MSB algorithm based on the fairness. based on the Graph coloring model, we proposed a dynamic"On Demand"channel assignment mechanism, which concerns the communication request from customer and added a channel reconfiguration process to save the computational cost. The simulation results show that these two algorithms have better performance in throughput, delay and computation complexity than the former static allocation algorithm in ordinary CR scenario.Based on the MDCA algorithm proposed with the Interference temperature model by Anh Tuan Hoang,we proposed an improved MDCFA algorithm with fairness considered. This algorithm can maximize the downlink and uplink throughput as well as the number of cognitive users with Effective Power control and channel allocation scheme. The simulation results show that the proposed algorithm can satisfy the system in system throughput, and improve the secondary users'number served in downlink communication process. In uplink side,The two algorithms show nearly the same result with customer maximum as the power control policy will over look the sub-channel difference.