Date Added: May 2012
Channel Idle Time Distribution (CITD) based secondary transmission strategies have been studied intensively in the literature. The performance of secondary devices are limited by the presumed CITD. But none of them provides a reasonable characterization of the CITD in reality. In this paper, the authors carefully examine the feature of the CITD using large amount of channel idle time data collected in various WLAN networks. It is demonstrated that the CITD can be well approximated by hyper-exponential densities. Based on the estimated density, they propose a novel multiple-shot transmission strategy which takes advantage of the hyper-exponential feature of the CITD.