Joint Coverage Enhancement by Power Allocation in Poisson Clustered Out-of-Band D2D Networks

In this paper, we consider a Poisson clustered out-of-band device-to-device (D2D) network operating in Rayleigh fading channels and propose two optimization schemes based on the joint coverage probability to allocate the transmit power to D2D user equipments (DUEs) in both the target cluster and the whole network. The joint coverage probability accounts for the spatial correlation of the interference among the DUEs. With a differing amount of location information being available among the DUEs in centralized and localized communication solutions, the joint coverage probability is formulated based on the coherent, non-coherent, and single-cluster approximated pairwise coverage probabilities. By maximizing the joint coverage probability formulated in this way, the robustness of the network can be enhanced. Meanwhile, to fulfill the green aspect of future 5G communications, the battery life of the DUEs will be prolonged by minimizing the power consumption for a given joint coverage probability requirement. The formulations of the two optimization problems above are not convex but are transformed to convex by using geometric programming. The simulation results show that, compared with the conventional LTE open loop and fixed power schemes, the joint coverage probability and power consumption are respectively optimized by applying the proposed schemes.