Can SWIPT-Based MEC System Benefit From mmWave Band: A Joint Beam, Task Offloading and Energy Harvesting Optimization Perspective

In this paper, we investigate the SWIPT (simultaneous wireless information and power transfer) based MEC (mobile edge computing) system in the mmWave band, where wireless devices offload partial tasks to the MEC server in the uplink, receive the computing result and harvest energy in the downlink. We focus on exploiting multiple beams in the mmWave band to enhance the multi-device downlink transmissions and maintain fairness among multiple devices. Specifically, we concentrate on the joint optimization of the uplink offloading, downlink beam management for multi-device transmissions, downlink power splitting within each beam for computing result receiving and energy harvesting, and time allocation between uplink and downlink. We formulate the joint optimization problem to maximize the minimum residual device energy. As the problem is a mixed-integer non-convex optimization program, we design a heuristic algorithm with low computing complexity, by relaxing the integer constraint and exploiting the successive convex approximation method. We carry out extensive simulations to verify our proposed algorithm performance. The simulations demonstrate that the joint optimization of beam management can increase the minimum residual energy and ensure the max-min fairness among multiple devices within the mmWave SWIPT-based MEC system.