Dynamic Spectrum ManagementCommon HoppingCognitive Radio Resource ManagementSpectrum UtilizationEngineeringProactive Spectrum HandoffSpectrum ManagementEdge ComputingCognitive RadioLicensed SpectrumInternet Of ThingsMobile ComputingSignal ProcessingCognitive NetworkUnlicensed Spectrum
Cognitive radio improves spectrum use by allowing unlicensed users to opportunistically access spectrum, but they must vacate when licensed users appear, and the random arrival of licensed users causes disruptions, low throughput, and high switching overhead. This work proposes a proactive spectrum handoff framework for CR ad hoc networks to mitigate these issues. The framework introduces channel‑switching policies, a proactive handoff protocol with network‑level rendezvous, and a distributed channel‑selection scheme to prevent collisions among unlicensed users. Simulations show the proactive protocol achieves higher throughput and fewer collisions than reactive handoff, and the channel‑selection scheme improves packet delivery rates over existing methods.
Cognitive radio (CR) technology is a promising solution to enhance the spectrum utilization by enabling unlicensed users to exploit the spectrum in an opportunistic manner. Since unlicensed users are considered as temporary visitors to the licensed spectrum, they are required to vacate the spectrum when a licensed user appears. Due to the randomness of the appearance of licensed users, disruptions to both licensed and unlicensed communications are difficult to prevent, which lead to low throughput and high spectrum switching overhead. In this paper, a proactive spectrum handoff framework in a CR ad hoc network is proposed to address these concerns. In the proposed framework, channel switching policies and a proactive spectrum handoff protocol are proposed to let unlicensed users perform spectrum switching before a licensed user uses the spectrum to avoid interference. A network coordination scheme for unlicensed users is also incorporated into the spectrum handoff protocol design to realize network rendezvous. Moreover, a distributed channel selection scheme to eliminate collisions among unlicensed users in a multi-user spectrum handoff scenario is proposed. Simulation results reveal that the proposed proactive spectrum handoff protocol outperforms the conventional reactive spectrum handoff approach in terms of higher throughput and fewer collisions to licensed users. It is also shown that the proposed channel selection scheme results in higher packet delivery rate compared with existing channel selection schemes.
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