Performance analysis for searching delay of secondary users in cognitive radios

Spectrum hand-off is an efficient way to utilize spectrum resources in Cognitive Radio. However, a lot of researches have been done without consideration of searching delay. In this paper, secondary users' searching delay, which cannot be ignored in actual situation, is considered with an improved three-dimension Markov approach for dynamic spectrum access. Theoretically, we use quasi-birth-and-death processes (QBDs) to describe Continuous-Time Markov chains (CTMC) for spectrum access process. Then through the analysis of the blocking probability, the dropping probability and the user capacity, we present how the secondary users' searching delay affects the performance of the system.