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.