HC-IPSAG and GC-IPSAG algorithm proposals: Cluster based IPSAG algorithm variations for large cognitive radio networks

The cognitive radio (CR) technology was proposed as a solution for the lack of wireless resources in an environment with a rapidly growing number of users. The CR advances the dynamic utilization of the licensed users' unused spectrum channels by secondary users. The paper looks into large CR networks by proposing two improved variants of IPSAG (IP Spectrum Aware Geographic routing algorithm). The destination geographical location is indirectly part of the routing metric that is proposed in IPSAG, and the main assumption on which IPSAG is based is that the source can always find the destination's position. This assumption is no longer valid in a very large network, so two ideas of keeping the IPSAG flexibility without geographic bounds are proposed. Both proposals are based on dividing the network into clusters, and differ in the way of how inter-cluster routing is performed. The first proposal, GCIPSAG, uses gateway nodes between clusters, without attempting to find where destination is located for inter-cluster routing. The second proposal, HC-IPSAG, is using an overlay network formed with cluster head nodes in order to locate the destination, and to inter-cluster route the packet.