Spectrum handoff in cognitive radio networks: A classification and comprehensive survey

The rapid progression in wireless networking has raised the demand of extra spectrum bands. The current fixed spectrum allocation policy used by the government agencies is unable to accommodate the growing demand of the wireless networks. The research in cognitive radio networks is envisaged to solve the problem of spectrum scarcity and inefficiency in spectrum usage. Hence, cognitive radio networks are providing high attention to wireless community which allows the dynamic use of the underutilized spectrum. The dynamic use of the available unutilized spectrum can be done by spectrum handoff. An extensive work has been carried out in the field of spectrum handoff for cognitive radio networks to fulfill the growing demand of extra spectrum. At present, there is no standardization, detailed classification and comprehensive survey exist for spectrum handoff schemes. This paper presents a detailed classification and comprehensive survey of existing spectrum handoff schemes for cognitive radio networks. The spectrum handoff schemes are classified into various categories which provide an overview of the active research initiatives in the area of spectrum handoff. On the synthesis of available spectrum handoff schemes, various research issues and challenges are also presented which require the attention of the researchers.