Spectrum Handoff in Cognitive Radio Cellular Network: A Review

For efficient wireless communication, the main resource is spectrum. Proper allocation of spectrum is one of the key requirements to effectively utilize the available resources. As the available spectrum is fixed and utilized by proper licensing and control, it is essential to use the spectrum to the extent possible to meet the ever increasing demand of various services including multimedia services that eat up more spectrums. Cognitive radio (CR) is a potential technology to solve spectrum scarcity problem for 5G cellular systems. CR provides flexibility, adaptability and interoperability. As CR users are opportunistic and try to use the licensed spectrum without causing any adverse effect on QoE of the licensed users. CR is the enabling technology, using which dynamic sharing of spectrum is done for unlicensed users to use frequency bands of the licensed users and hence improve the spectrum utilization. In CR, secondary users may require spectrum handoff when licensed users arrives and the channels currently being used by secondary user should be returned to the primary users. This paper, provide a survey of spectrum handoff in cognitive radio network (CRN). We have first introduced the cognitive radio network and concept of spectrum holes. Then this paper discuss about functions of CRN. Also, the concept of Quality of Experience (QoE) in CRN is explained. Subsequently, some recently proposed spectrum handoff algorithms in CRN are reviewed and different approaches to handle spectrum handoff are described. Finally, the paper is concluded with outlining the directions for future research in this area.