Optimal Power Allocation for Maximizing Energy Efficiency in DAS-Based IoT Network

Distributed antenna system based on simultaneous wireless information and power transfer (SWIPT) can be one of the promising solutions in maximizing energy efficiency (EE), where ultra low power devices harvest energy in power splitting (PS) mode. The paradigm shift of the internet-of-things (IoT) has increased the number of IoT devices and associated sensitive data exchange on the internet. Like the EE is a noteworthy aspect in ultra low power devices, energy harvesting (EH) is an active approach from surrounding electromagnetic sources. This article deals with EE maximization for SWIPT using PS mode. In the SWIPT system, this article presents a tradeoff between EE and spectral efficiency and proposes an algorithm, which allocates optimal power to each distributed antenna port. For an IoT device, the PS scheme implements EH and information decoding operations. The proposed algorithm is based on the Lagrangian multiplier method and Karush-Kuhn-Tucker conditions to find the optimal solution without iterative computation compared to the conventional iterative method. Simulation results reveal that the proposed algorithm achieves maximum energy transfer by the using optimal PS ratio.