  Traditional concept of cognitive radio is the coexistence of primary and
secondary user in multiplexed manner. we consider the opportunistic channel
access scheme in IEEE 802.11 based networks subject to the interference
mitigation scenario. According to the protocol rule and due to the constraint
of message passing, secondary user is unaware of the exact state of the primary
user. In this paper, we have proposed an online algorithm for the secondary
which assist determining a backoff counter or the decision of being idle for
utilizing the time/frequency slot unoccupied by the primary user. Proposed
algorithm is based on conventional reinforcement learning technique namely
Q-Learning. Simulation has been conducted in order to prove the strength of
this algorithm and also results have been compared with our contemporary
solution of this problem where secondary user is aware of some states of
primary user.
