Research Of Schedule Strategy For Traffic In Cognitive Radio Networks

The scarcity of radio spectrum becomes one of the main obstacles of constraining the development of wireless communication , cognitive radio provides reliable communications and high effective utilizations of spectrum by sensing wireless communication environment,study from environment and revises system operating parameters adaptively basing on statistical characteristic of environment. The available spectrum of cognitive radio system changes with the state of shared spectrum change, providing reliable QoS guarantee for different traffic by using dynamical spectrum it is one of key technologies which were solved in cognitive radio system radio resource management. Relay on the NSF project which named 'The topology management, MAC mechanisim and adaptive resource allocation of Cog-MESH network', this paper focus on the research of Cognitive Radio Wireless Regional Area Network( (WRAN) schedule strategy for traffic, the main contents are:1)Introduced cognitive radio basic concept,principle and system configuration, we analysze layered configuration system and basic function in every layer of WRAN basing on IEEE802.22 protocol; we intensive expatiate QoS guarantee mechanism in the CR-MAC layer from two aspects which are traffic management and QoS guarantee, put forward improvement measures across the layer in allusion to the existing problems.2)The schedule algorithm for traffic is one of sticking points which achieves QoS guarantee,Based on contrasting and analyzing basic principle and technologies characteristic of typical schedule algorithms for traffic and application scene of WRAN, an improved QoS guarantee adaptive scheduling algorithm was proposed. The schedule strategy proposed can guarantee traffic QoS requirements for individual user and fairness for multi-users.3)To solve the rapid drop of user QoS under network congestion,improve the accuracy of user QoS and advance the ability of dynamic adjustment,a dynamic self-configuration method for user QoS protection was proposed. Utility function was introduced to initialize the priorities of user QoS,and then the active features of cognitive network and the interruption management were utilized to determine the priorities and also correct them dynamically by cognitive nodes.4)Through establishing emulation testing platform,we analyze and validate the performance of traffic schedule algorithm and dynamic self-configuration method, The simulation results show that the schedule strategy proposed can guarantee traffic QoS requirements for individual user and fairness for multi-users,while utilizing the bandwidth effectively.