Research For Cross-Layer Routing Protocol In Cognitive Networks

With the high speed development of wireless and mobile communications, the limited spectrum resources have no way to meet the increasing communication needs. Besides, the existing spectrum resources are allocated statically, which causes most spectrums are not able to be taken full advantage while some hot spectrums are overloaded. To resolve these problems, people propose the concept of cognitive radio. Cognitive radio network is composed of cognitive nodes which adopt cognitive radio technology. Cognitive nodes can perceive radio spectrum information actively, wait an opportunity to access to the most suitable spectrum, and transmit date in ad hoc.Through comprehensively analyzing the current development and research situation of cognitive radio technology and networking method of cognitive radio network, this paper discusses the existing routing protocol of cognitive radio network in detail and points out the problems. Based on this, this paper mainly discusses and analyzes how to apply AODV routing protocol to cognitive networks.This paper proposes a cross-layer routing protocol design for cognitive networks, which first introduces a new protocol layer named Common Information Exchange (CIE). CIE implements the function of information sharing between upper layer and lower layer. Through CIE, routing layer can acquire the wireless spectrum resource detected by MAC layer and denote the working frequency band of next hop when the lower layer transmits data package. Besides, the routing protocol designs a novel routing table and adjacent node table for cognitive networks according to its characteristics. Taking into account that the primary user may appear at any time, which requires cognitive nodes can also be forced to change the working frequency band according to detecting results, this paper designs an adjacent nodes repair mechanism specially, which ensures that the original route keep smooth after the cognitive nodes change the working frequency band, and reduces unnecessary routing overhead.This paper builds a cognitive network simulation platform using NS2. Based on the platform, a large number of simulation is done according to the proposed cross-layer routing protocol. The simulation results show that the proposed cross-layer routing protocol is suitable for cognitive network.