Spectrum sensing and data transmission tradeoff in cognitive radio networks

In cognitive radio networks, a cognitive source node typically requires two essential phases to complete a cognitive transmission process: the phase of spectrum sensing with a certain time duration to detect a spectrum hole (thus also referred to as spectrum hole detection phase) and the phase of data transmission through the detected spectrum hole. In this paper, we focus on the analysis of cognitive transmissions by jointly considering the two phases. An exact closed-form expression of an overall outage probability that accounts for both the probability of no spectrum hole detected and the probability of a channel outage is derived for cognitive transmissions. Based on the derived overall outage probability, we investigate the spectrum hole utilization efficiency, which is used to quantify the percentage of spectrum holes utilized by the cognitive source for its successful data transmission. Numerical results show that there is a tradeoff in determining the time durations for hole detection and data transmission phases in order to maximize the spectrum hole utilization efficiency.