Dynamic Spectrum Aggregation Strategies with Consideration of Spectrum Handoff in Cognitive Radio Networks

• Main Authors: Wei-YuanCheng, 鄭維元
• Other Authors: Ching-Fan Hsu
• Format: Others
• Language: en_US
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/65078309345129457406

碩士 === 國立成功大學 === 資訊工程學系 === 103 === To enhance spectrum utilization in wireless connections, the concept of cognitive radio networks has been proposed to effectively utilize unoccupied spectrum through spectrum cognition. In cognitive radio networks, a group of primary users are privileged to access its licensed channel, while another group of secondary users equipped with cognitive radio can detect the activities of primary users and utilize idle channels. If primary user reclaims a channel used by a secondary transmission, the secondary user has to perform spectrum handoff which generates channel switching delay and interferes the quality of primary transmissions. The spectrum handoff issue becomes more serious when spectrum aggregation is utilized in secondary networks. Spectrum aggregation is known as a technique enabling secondary users to transmit on multiple idle channels simultaneously to achieve higher data rates. However, using additional channel may increase the chance of interrupt by primary users during secondary transmissions. To this end, it is important to reduce the number of spectrum handoff for a secondary user in order to provide stable transmission under the dominance of primary users in cognitive radio systems. In this thesis, we considered the tradeoff between spectrum aggregation and spectrum handoff in multi-channel selection problem. The problem is to find an appropriate set of channels for secondary users who can transmit more data before the channels being reclaimed by primary users. We have to reduce the number of spectrum handoff required and the propagation delay for secondary transmission. For multi-channel selection, we propose multiple dynamic spectrum aggregation strategies with the consideration of spectrum handoff in cognitive radio networks. In the simulation, we evaluate multiple spectrum aggregation algorithms under heterogeneous channel characteristics. Simulation results demonstrate that the proposed algorithm can reduce the effect of spectrum handoff and enhance throughout at about 35% for secondary transmissions.