Date Added: Aug 2009
The authors propose a model-based channel access mechanism for cognitive radio-enabled secondary network, which opportunistically uses the channel of an unslotted primary network when the channel is sensed idle. They have considered IEEE 802.11 WLAN as a de facto primary network operating in ISM band. The paper focuses on a single WLAN channel that is used by WLAN clients and a WLAN server for a mix of Email, FTP, and HTTP-based web browsing applications. They model the occupancy of the channel by primary WLAN nodes as an alternating renewal process. The secondary node uses the model to estimate residual idle time duration after the channel is sensed idle, and opportunistically transmits frames in that duration.