Cross Layer Protocols in Cognitive Networks

Abstract

The ever increasing demand for communication bandwidth and inefficient usage of the existing spectrum has led to spectrum scarcity. The inefficient usage of the existing spectrum can be improved through opportunistic access to the licensed bands without interfering with the primary users. Cognition should also be included in upper layers of the network to effectively utilize the benefits of cognitive radio and dynamic spectrum allocation Routing and spectrum access in cognitive environment is a challenging task as the channel availability is constrained by the presence of primary users The problem of routing in cognitive networks targets the creation and maintenance of wireless multihop paths among cognitive nodes by deciding both the spectrum to be used and the relay nodes of the path This thesis proposes a cognitive cross layer routing protocol which jointly does power control and spectrum selection for multiple hops in the routing path and a medium access protocol for cognitive networks The proposed protocol provides solutions for the multi channel hidden node problem channel synchronization channel scheduling and other challenges that arise in the design of cognitive networks For performance evaluation the proposed protocols are implemented in NS2 and a comparative analysis is also done against existing It also develops a Markov model for the performance analysis of the proposed cognitive MAC protocol The developed model is generalized and can be used for performance analysis of any IEEE 802.11 power saving mode based cognitive MAC protocol for ad hoc networks It proposes Protocols specific to cognitive wireless sensor networks and a network architecture for cognitive wireless sensor networks which consists of hierarchical distributed minimum spanning trees Cognitive users must be aware of primary user s location within the region of interest for calculating disable region It applies a leveling and sectoring based approach for primary user localization which will avoid the interference to hidden primary users