Novel Hybrid Spectrum Handoff for Cognitive Radio Networks

Cognitive radio (CR) is pro jected as a technology (or solution) that will raise the spectrum utilizat ion considerably by allowing low-priority or secondary user (SU) to utilize the spectrum of high-priority or primary user (PU) opportunistically. Spectru m handoff is a different type of handoff necessitated by the reappearance of the primary user on the frequency channels occupied by the secondary user at that time and location. In this paper, a hybrid type of spectrum handoff algorith m is proposed where proactive decision and reactive decision approaches are combined. Depending on the arrival rate o f primary user (i.e. PU activ ity), the algorith m switches fro m reactive decision mode to proactive decision mode and vice versa. The switching fro m one mode to another mode depends on threshold value of PU activity and we evaluated the threshold value through analysis for switching of the algorithm to be 0.37. Simu lated results show that the proposed hybrid spectrum handoff algorith m reduces the total service t ime of secondary user considerably compared to conventional proactive decision or reactive decision handoff approaches.