NeXt generation/dynamic spectrum access/cognitive radio wireless networks: a survey
Computer Networks: The International Journal of Computer and Telecommunications Networking
Analysis of cognitive radio spectrum access with finite user population
IEEE Communications Letters
VoIP capacity analysis in cognitive radio system
IEEE Communications Letters
Voice service support over cognitive radio networks
ICC'09 Proceedings of the 2009 IEEE international conference on Communications
Performance analysis of an unslotted CSMA in the multi-channel cognitive radio networks
Proceedings of the 5th International Conference on Queueing Theory and Network Applications
IEEE Journal on Selected Areas in Communications
| Hi-index | 0.00 |
We analyze the performance of a carrier sense multiple acess (CSMA) taking account of propagation delay in an un-slotted multi-channel cognitive radio network. In this system, every SUs sense channel before transmission by random sensing mechanism. If a secondary user senses the channel being busy by either primary user (PU) or secondary user (SU), then the SU repeats the same procedure after an exponential distributed vacation time. If a SU senses the channel being idle, then the SU transmits a packet, and after packet transmission, the SU goes to an exponential distributed vacation time. In reality, we need to take account of a propagation delay for node's signal to reach the other nodes. If another SU senses the same channel during a SU's propagation delay, then the SU recognizes the channel being idle and sends packet which will collide with the packet of the previous SU. We model the above described multi-channel cognitive radio network by a 4-dimensional continuous time Markov chain (CTMC) and obtain the steady state probability of the CTMC by matrix analytic method. We obtain performance measures such as the throughput of SUs, the collision probability of SUs and interference probability of SUs with PUs. Numerical results show that the propagation delay causes serious degradation on the throughput of SUs in unslotted multi-channel cognitive radio networks.