A lower bound on multi-hop transmission delay in cognitive radio ad hoc networks

This paper analyzes the delay of multi-hop transmissions in cognitive radio ad hoc networks (CRNs) to investigate the performance of routings in CRN. Compared to routing in ad hoc networks, additional medium access delay is introduced in CRN since opportunistic transmissions of secondary users (SUs) should not violate the interference constraints at primary receivers. Moreover, additional retransmission delay occurs in CRN because received signals at SUs are interfered with by both primary transmitters and concurrent secondary transmitters. We propose an analytically tractable model to investigate routings in CRN considering medium access delay, retransmission delay and the hop count of the end-to-end route. Through optimizing the number of hops of the end-to-end route, a lower bound on the end-to-end packet transmission delay is developed, which facilitates delay QoS provisioning and rate-delay trade-off in CRN. Consequently, this research serves as the valid framework for baseline performance analysis and offers novel avenues to routing design in CRN.