This paper proposes and investigates a green virtualization framework forinfrastructure sharing among multiple cellular operators whose networks arepowered by a combination of conventional and renewable sources of energy. Underthe proposed framework, the virtual network formed by unifying radio accessinfrastructures of all operators is optimized for minimum energy consumption bydeactivating base stations (BSs) with low traffic loads. The users initiallyassociated to those BSs are off-loaded to neighboring active ones. A fairnesscriterion for collaboration based on roaming prices is introduced to cover theadditional energy costs incurred by host operators. The framework also ensuresthat any collaborating operator is not negatively affected by its participationin the proposed virtualization. A multi-objective linear programming problem isformulated to achieve energy and cost efficiency of the networks' operation byidentifying the set of inter-operator roaming prices. For the case whencollaboration among all operators is infeasible due to profitability, capacity,or power constraints, an iterative algorithm is proposed to determine thegroups of operators that can viably collaborate. Results show significantenergy savings using the proposed virtualization as compared to the standalonecase. Moreover, collaborative operators exploiting locally generated renewableenergy are rewarded more than traditional ones.
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