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A Collaborative MAC Protocol with Heterogeneous Energy Harvesting and Dynamic Spectrum Sensing
Bin Zhang, Liu Yang and Yi Liu
To handle the insufficiency of energy and spectrum resources in wireless networks, energy harvesting-assisted cognitive radio technology becomes a promising solution. By considering multiple users’ cases, the inter-user sensing cooperation is able to improve both sensing and energy efficiency. However, two issues will arise: 1) how many users should be selected for cooperative sensing, and 2) how to allocate the energy resource in cooperative sensing. To address these two issues, we propose a collaborative medium access control (MAC) protocol in which the users selected for cooperative sensing have heterogeneous energy harvesting capabilities. In the proposed MAC protocol, the users can be convened to participate the cooperative sensing unless their residual energy level is below a pre-determined threshold. Considering the tradeoff between the throughput and the overhead, we formulate an achievable throughput maximization problem to optimize the number of users that participate in cooperative sensing and the sensing energy consumed by each user for each channel. The theoretical analysis is presented to derive the achievable throughput, sensing overhead and energy consumption. Numerical results illustrate that the proposed MAC protocol can outperform the existing MAC protocols with different sensing methods.
Keywords: 5G networks, energy harvesting, cooperative MAC, cognitive radio