Abstract:

In the cognitive radio network，when the primary users show up，the secondary users should vacate the channel and find another free channel for data transmissions.This is the so-called spectrum handoff.There are two most important performance metrics for spectrum handoff：handoff delay and handoff times.A novel spectrum handoff scheme with channel sensing sequencing was proposed in order to decrease both handoff delay and handoff times.When designing the channel sensing sequence，the channel free probability was considered，and the probability that no handoff will happen in a channel was considered as well.The simulation results show that the method not only can get the minimum handoff delay as the traditional method does，but also can decrease the handoff times were significantly compared with the traditional method.

Key words: spectrum handoff, handoff delay, handoff times, channel sensing sequencing