Cognitive radio intelligent-MAC (CR-i-MAC): channel-diverse contention free approach for spectrum management

Cognitive radio was introduced to fill up the imbalance between spectrum scarcity and spectrum underutilization. So to make such an ideology work, a network which can utilize all the available channel in the best efficient manner, without causing any harmful interface to primary user (PU) and maintaining the Quality of Service (QoS) for cognitive user (CU) is required. In both Mesh as well as ad-hoc networks, effective utilization of the white-spaces by the CUs maintaining the QoS for both primary and CU is a challenging task due to the frequent and instant change in their channel status. In this paper an intelligent-MAC (i-MAC) for cognitive radio (CR) using two transceivers based on hybrid approach of combination of cooperative decision and contention-free approach is proposed. Cooperative decision, to overcome hidden node or the case when there is no common channel between the CU’s and contention-free approach, to solve the issues in contention mechanism, where same channel is selected simultaneously by multiple CU’s. Proposed CR-i-MAC permits an effective dynamic spectrum access to CUs without effecting the QoS for PU’s. The simulative performance analysis of proposed CR-i-MAC is tested in various critical cases like multi-channel single-radio and multi-channel multi-radio over different on demand routing protocols like dynamic source routing, ad-hoc on demand distance vector and weighted cumulative expected transmission time using network simulator (NS-2). The performance of the network is measured on the basis of parameters like throughput, delay and interference. The analysis of the simulation results shows that the proposed CR-i-MAC outperforms various other CR MAC’s in terms of both increased throughput and reduced delays thereby making the system stable and efficient.