TDMA for primary users and CSMA for secondary users in a cognitive radio network

Both TDMA and CSMA are effective media access protocols, which can also be important elements of more advanced protocols. In this paper, we investigate TDMA and slotted CSMA protocols in a cognitive radio network, where primary users have higher priority than secondary users and secondary users need to monitor the channel to avoid interference to the primary users. It is thus proposed that TDMA is used for primary users to access the channel and secondary users use slotted CSMA to sense the time slots of TDMA and transmit their packets during idle time slots. A Rayleigh fading channel is considered and we derive the throughput of TDMA and slotted CSMA for the primary and secondary networks.