Energy Efficient Joint User Association and Power Allocation in Relay Aided Mass

Energy efficiency is an important metric for downlink transmission in an amplify-and-forward relayaided massive multiple-input multiple-output system, but has not been well investigated. In this work, considering the characteristics of such a system and quality-of-service requirements of users, the energy-efficient joint user association and power allocation problem is studied. First, the closed-form expression of system energy efficiency under the proportional fairness criterion is derived. The