Institute of Electrical & Electronic Engineers
In the context of primary/secondary spectrum sharing, the authors propose a randomized secondary access strategy with access probabilities that are a function of both the primary Automatic Repeat reQuest (ARQ) feedback and the spectrum sensing outcome. The primary terminal operates in a time slotted fashion and is active only when it has a packet to send. The primary receiver can send a positive ACKnowledgment (ACK) when the received packet is decoded correctly. Lack of ARQ feedback is interpreted as erroneous reception or inactivity. They call this the explicit ACK scheme. The primary receiver may also send a Negative ACKnowledgment (NACK) when the packet is received in error.