Sensing for opportunistic spectrum access in cognitive radio: Exploitation of the time to the dead-line

This paper investigates some sensing strategies for a secondary user which has to stop its transmissions within a fixed time when a primary user begins to transmit. Instead of stopping the transmission as soon as a primary user is detected, the fixed time given by the regulation to leave the medium can be exploited until its dead-line by the secondary user. For this purpose, an appropriate sensing strategy has to be used. We show in this paper how to exploit this time to the dead-line. In order to do so, the parameters to tune will be the length and the periodicity and the number of quiet periods used by the secondary user in order to perform sensing. The constraints are to meet a probability of false alarm and of detection for a given sensibility level (in dB). We will show how the channel use of the secondary user may benefit of the exploitation of transmission until the dead-line.