Joint power and rate scheduling for cognitive multi-access networks with imperfect sensing

A cognitive multi-access network in which a primary user and a secondary user transmit to a common receiver is considered. The secondary user senses the channel at the beginning of each time slot to determine whether the primary user is active or idle. The sensing is not perfect; hence, the secondary user can miss the detection of an active primary user or erroneously declare an idle primary user as active. The secondary user can vary its transmission rate and power from a time slot to the other. A joint rate and power scheduling algorithm is proposed that minimizes the probability of packet loss of the secondary user under a maximum probability of collision constraint at the primary user and a constraint on the average power transmitted by the secondary user. The case in which no retransmissions are allowed and the cases in which one or both users retransmit the collided packets are also considered. The problem is posed as a linear optimization problem that can be solved efficiently. © 2013 Liao et al.; licensee Springer.