Abstract
In cognitive radio networks, the secondary users (SUs) switch the data transmission to another empty spectrum band to give priority to primary users (PUs). In this paper, channel switching in cognitive radio mobile ad hoc networks (CR-MANETs) through an established route is modeled. The probability of channel availability in this route is calculated based on the PU's activity, SU's mobility, and channel heterogeneity. Based on the proposed model, the channel and link availability time are predicted. These predictions are used for channel assignment in the proposed channel allocation scheme. A handoff threshold as well as a life time threshold is used in order to reduce the handoff delay and the number of channel handoffs originating from the short channel usage time. When the channel handoff cannot be done due to the SU's mobility, the local flow handoff is performed to find an appropriate node in the vicinity of a potential link breakage and transfer the current data flow to it. The local flow handoff is performed to avoid possible flow disruption and also to reduce the delay caused by the link breakage. The study reveals that the channel heterogeneity and SU's mobility must be considered as important factors, which affect the performance of the handoff management in the CR-MANETs. The results emphasize on the improvement of the route maintenance probability after using the local flow handoff. It is also stated that the amounts of handoff requirement and handoff delay are decreased after using the predicted channel usage life time and handoff threshold time.
Highlights
Over the last few decades, the world has experienced an explosion of the wireless devices
We can see that the probability of channel availability through a route is dependent on the activity of the primary users (PUs) and the total number of available channels, and it decreases as the number of hops increases
8 Conclusions Spectrum handoff is extremely challenging in cognitive radio networks, especially in CR-MANETs because of frequent topological variations, limited power and channel transmission range, bandwidth constraints, and lack of a central controlling entity
Summary
Over the last few decades, the world has experienced an explosion of the wireless devices. Based on the channel availability modeling, the unified spectrum handoff scheme must be proposed to include different mobility events in CR-MANETs, such as spectrum and user mobility, channel quality degradation, and topologic variation. Assume that two mobile nodes with a distance less than Rl are communicating in an active route while they are using a channel of type l for their data transmission When their distance exceeds the Rl, they must change their communication channel and find a channel with a transmission range longer than Rl. When their distance exceeds the Rl, they must change their communication channel and find a channel with a transmission range longer than Rl When the spectrum handoff cannot be implemented in one hop, the local flow handoff will be established to maintain communication
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