A Cluster-based Link Recovery Mechanism for Spectrum Aware On-demand Routing in Cognitive Radio Ad Hoc Networks

• Main Authors: Chih-ChiehTang, 湯智傑
• Other Authors: Kuo-Feng Ssu
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/73131919527336284561

碩士 === 國立成功大學 === 電腦與通信工程研究所 === 100 === In cognitive radio ad hoc networks (CRAHNs), link failures among secondary users (SUs) primarily result from sudden appearance of primary users (PUs). Many researches about routing protocols in CRAHNs apply on-demand routing protocols. They usually adopt the route recovery process of traditional on-demand routing protocols without modification in CRAHNs. In traditional route recovery process, nodes with link failure drops data packets and sends route error packets (RERRs) to source nodes to find new routes. Much packet loss occurs until the routes are recovered. And traditional on-demand routing protocols are proposed for mobile ad hoc networks (MANETs). There can be some improvement in route recovery mechanism in CRAHNs. This thesis proposes a cluster-based link recovery mechanism (CLR) for AODV in CRAHNs. Different from the traditional method of route reestablishment, CLR recovers failed links locally and the original routes do not change. Because the original routes do not change, the data packets can be cached in the buffer. After the links are recovered, data packets can be sent. The amount of packet loss decreases. Furthermore, this thesis observes that if there is an intersection area of all PUs' radio coverage in the network, and there are some SUs in the area. No matter what channels these SUs choose, links between these SUs are apt to break. CLR can recover all link failures by using clustering method and effectively increases end-to-end throughput and successful packet delivery fraction.