  Coexistence by means of shared access is a cognitive radio application. The
secondary user models the slotted primary users channel access as a Markov
process. The model parameters, i.e, the state transition probabilities
(alpha,beta) help secondary user to determine the channel occupancy, thereby
enables secondary user to rank the primary user channels. These parameters are
unknown and need to be estimated by secondary users for each channel. To do so,
the secondary users have to sense all the primary user channels in every time
slot, which is unrealistic for a large and sparsely allocated primary user
spectrum. With no other choice left, the secondary user has to sense a channel
at random time intervals and estimate the parametric information for all the
channels using the observed slots.
