  In a cognitive radio system the failure of secondary user (SU) transceivers
to promptly vacate the channel can introduce significant access-latency for
primary or high-priority users (PU). In conventional cognitive radio systems,
the backoff latency is exacerbated by frame structures that only allow sensing
at periodic intervals. Concurrent transmission and sensing using
self-interference suppression has been suggested to improve the performance of
cognitive radio systems, allowing decisions to be taken at multiple points
within the frame. In this paper, we extend this approach by proposing a
sliding-window full-duplex model allowing decisions to be taken on a
sample-by-sample basis. We also derive the access-latency for both the existing
and the proposed schemes. Our results show that the access-latency of the
sliding scheme is decreased by a factor of 2.6 compared to the existing slotted
full-duplex scheme and by a factor of approximately 16 compared to a
half-duplex cognitive radio system. Moreover, the proposed scheme is
significantly more resilient to the destructive effects of residual
self-interference compared to previous approaches.
