Research On Spectrum Handover In Cognitive Radio Networks

Cognitive radio technology is effective conflict resolution between open spectrum resource scarcity and low efficiency of specially authorized spectrum. It will cause no interference while sharing wireless spectrum opportunities with licensed users, consequently improving the wireless spectrum resource utilization. Spectrum handover is one of the key technologies in cognitive radio. In this paper, we mainly study the spectrum handover deeply.According to different reasons caused by handover, this paper designs a kind of new spectrum handover mechanism. Regarding to spectrum handover caused by the emergence of licensed users, the author puts forward Spectrum hole matching algorithm based on handover probability. When handover takes place but not due to licensed users, a target handover channel selection algorithm based on bidding is proposed. The specific works are as follows:Chapter Three describes the network environment and structure is studied in this paper, simply introduces two handover judging methods of single attribute and multiple attribute. In the new spectrum handover mechanism, the reason cause the handover attributed to two situations that the licensed users appear or not, and according to different situations use different algorithms to execute handover.Regarding to spectrum handover caused by the emergence of licensed users, through the elaboration of handover probability and quality of service, the fourth chapter puts forward Spectrum hole matching algorithms based on handover probability, considering service quality requirements of Secondary User and effective allocation of wireless spectrum resource. Because of considered resource allocation, the matching results do not all meet the service quality requirements. Thus as a supplement, this paper further presents spectrum hole reservation algorithm. It will reserve spectrum for Secondary User with low service quality. The simulation results show that the algorithm can reduce times of spectrum handover for secondary users as well as guarantee the quality of service.Pointing to spectrum handover caused by non-licensed users, the fifth Chapter introduces auction theory and transfers selection of target handover channel to simple auction, then designs a kind of target handover channel selection algorithm based on bidding. In bidding process, secondary users are graded, making different business to have different priority. Meanwhile interference price is defined to limit the interference for licensed users. The simulation results show that the proposed algorithm can reduce interference to a licensed user, and guarantee timely transformation of real-time service while available channel is in insufficiency.