Research And Implementation Of Stable Routing Algorithm In Cognitive Wireless Hoc Ad Networks

With the rapid development of radio technology, communication network and the increment of the wireless bandwidth demand, spectrum resources become increasingly scarce. The scarcity of spectrum and the underutilization of the licensed frequency bands have motivated the development of Cognitive Radio (CR) technology. Cognitive Radio Ad Hoc Networks (CRAHNs) is a kind of Ad Hoc network which integrate CR technology. The existing routing algorithms in Ad Hoc networks cannot be directly applied in CRAHNs. In recent years, various routing metrics, algorithms and protocols in CRAHNs have been developed, but the routing metric and algorithm considering link stability still need further study. As the Secondary Users (SUs) in CRAHNs opportunistic use the unused spectrum which is authorized to the Primary user (PUs), and SUs node’s mobility can lead to instability of the link and seriously affect the CRAHNs network performance. We study the routing problem with the goal of link stability in this paper.1) At first, existing routing metrics and algorithms in CRAHNs are analyzed systematically. The existing routing metrics in CRAHNs can be categorized into six types, namely:throughput based, delay based, location based, energy based, link stability based and mixing various routing metrics.2) The stability routing metric CMID based on mobility prediction is proposed in this paper, CMID mainly includes four factors:channel their heterogeneity which includes channel bandwidth, channel stability, and channel utilization, the mobility of the node, the interference of the link and the distance between the nodes.3) On the basis of stability routing metric CMID, a stable routing and spectrum allocation algorithm with QoS constrains MRS2Q in CRAHNs is proposed. The basic idea of MRS2Q is:the next hops are chose based on routing metric CMID in a sector area which can change. In order to control the length of the routing path, the sector area central angle is initialized 90 degrees, if the next-hop node can’t be find in the sector area, then the central angle sector areas are increased, until the next-hop node be find in the sector areas.4) Lastly, we present a comprehensive evaluation on the performance of the proposed algorithm using NS2. The simulation considers the following two aspects: analyzing the average throughput and the average delay with node movement speed and the number of the primary nodes number. Simulation results show that the proposed stability metric CMID and the spectrum allocation algorithm can construct a stable routing path and have a better network performance comparing to other routing algorithms.