OPPORTUNISTIC MAC FOR DISTRIBUTED COGNITIVE RADIO

Abstract

Spectrum is one of the most important resources in wireless communication. With rapid increase in growth of wireless technology, spectrum requirement has also increased. Fixed spectrum assignment policy does not utilize the spectrum efficiently and it causes spectrum scarcity problem. The cognitive radio solves this issue by accessing spectrum dynamically. In this technique, medium access control (MAC) layer performs sensing scheduling, spectrum sharing, tradeoff between sensing and access. The MAC protocols uses the sensing information to access the spectrum conditional basis. To access spectrum dynamically, there is a need to design MAC protocol having high data transmission rate for secondary network and less number of collisions faced by primary users. In this method, data transmission rate of the cognitive network is increased by reducing the time period of contention phase in the time frame allotted at the MAC layer by starting data transmission just after reservation. Secondary user will not wait for the contention phase to be finished. This method addresses the issue of delay sensitive application by reserving some part of contention phase length for them. The performance of proposed MAC protocol is compared with the existing OSA MAC protocol along with the simulation results.