LAUSR

This paper studies an energy-efficient beamforming and resource allocation for multi-access edge computing (MEC) systems consisting of multi-antenna access points (APs) and single-antenna users. We consider maximizing energy efficiency (EE) of a MEC system, defined as the total computed bits per total energy consumption of the MEC system. To enhance the EE performance, we employ multiple antennas at APs to exploit multiplexing- or (receive) beamforming-gain in the uplink and perform download beamforming for transmitting computation results in the downlink. We consider both spatial-division multiple access (SDMA) based MEC system and time-division multiple access (TDMA) based MEC system and compare their EE performance. We formulate EE maximization problems for the SDMA-based and TDMA-based MEC systems, which are nonconvex and thus cannot be solved by standard convex optimization techniques. We first transform the problems by applying semidefinite relaxation (SDR). Then, we solve the relaxed problems for the SDMA-based MEC system and TDMA-based MEC system by using Dinkelbach method and difference-of-concave programming algorithm. We observe that the SDMA-based MEC system outperforms the TDMA-based MEC system in EE performance most of the cases. However, for the special case when i) only users’ energy consumption is counted (i.e., energy consumption of AP and MEC server is not considered) for EE, and ii) there is no minimum throughput requirement, we show that the TDMA-based MEC system outperforms the SDMA-based MEC system. Simulation results demonstrate that the proposed schemes significantly enhance the EE of MEC systems.