Spectrum Handover Scheme Based On Dynamic Channel Reservation In Cognitive Radio

Nowadays there is a great improvement in the speed and the quality of the communication. However, with the requirement of the wireless traffic increases, resource scarcity becomes more serious. Test results concerned show that the spectrum efficiency is low in some frequency bands owing to static spectrum allocation. Cognitive radio technology, which is based on dynamic spectrum allocation, can obtain information of surrounding wireless environment, find idle spectrum and transform parameters adaptively to reuse the spectrum source dynamically. Thus, cognitive radio attracts extensive attention in communication field.As a key technology of cognitive radio, on the one hand, spectrum handover allows secondary users to avoid interference to primary users timely and ensure the high priority of primary users in using spectrum. On the other hand, spectrum handover guarantees secondary users to keep the communication continuity by switching to other suitable target channels to resume the traffic.Spectrum handover scheme based on channel reservation is studied in this paper. As one of the three common spectrum handover mechanism, channel reservation can be used in a wide range and attracts extensive attention from standard organization and other researchers. However, there is a main drawback in existing schemes, that is, the static channel reservation scheme which reserves proper number of channels for spectrum handover causes high blocking probability and low throughput. To solve this problem, this paper proposes a spectrum handover mechanism based on dynamic channel reservation. By analyzing the feature of the primary users, the probability of spectrum handover of secondary users can be obtained according to renewal theory. Considering the prediction result, the system setting and the usage of current spectrum resource synthetically, the number of reserved channel can be determined finally. The numeric calculation results base on Markov analysis show that the proposed scheme can decrease the blocking probability and increase the throughout with the dropping probability keep unchanged. In all, the scheme improves the performance of the cognitive radio system greatly. Additionally, the proposed scheme puts different kinds of service into consideration and integrates the dynamic channel reservation mechanism and queuing up mechanism so as to apply to different kinds of service.