Joint User-Channel Assignment for Efficient Use of Renewable Energy in Hybrid Powered Communication Systems

In this paper, we introduce a new green resource allocation problem using hybrid powering of the communication system from renewable and non-renewable sources. The objective is to efficiently allocate the power delivered from different micro-grids to satisfy the users' requirements. Minimizing a defined power cost function instead of the net power consumption aims to encourage the use of the available renewable power through collaboration between base stations within and outside the different micro-grids. The different degrees of freedom in the system, ranging from assignment of users to base stations, possibility of switching the unnecessary base stations to the sleep mode, and dynamic allocation of the available bandwidth, allow us to achieve important power cost savings. Although the formulated optimization problem is a mixed integer-real problem with a non-linear objective function, we propose an efficient two-step algorithm to jointly assign users to base stations and the shared bandwidth among users. The users-to-base stations assignment is inspired from the bin-packing approach while the bandwidth allocation is performed through the bulb-search approach. Simulation results confirm the important savings in non-renewable power consumption when using the proposed approach.