Energy Efficiency Maximized Resource Allocation for Opportunistic Relay‐Aided OFDMA Downlink with Subcarrier Pairing

Abstract

This paper studies the energy efficiency (EE) maximization for an orthogonal frequency division multiple access (OFDMA) downlink network aided by a relay station (RS) with subcarrier pairing. A highly flexible transmission protocol is considered, where each transmission is executed in two time slots. Every subcarrier in each slot can either be used in direct mode or be paired with a subcarrier in another slot to operate in relay mode. The resource allocation (RA) in such a network is highly complicated, because it has to determine the operation mode of subcarriers, the assignment of subcarriers to users, and the power allocation of the base station and RS. We first propose a mathematical description of the RA strategy. Then, a RA algorithm is derived to find the globally optimum RA to maximize the EE. Finally, we present extensive numerical results to show the impact of minimum required rate of the network, the user number, and the relay position on the maximum EE of the network.

Green IoT for Eco-Friendly and Sustainable Smart Cities: Future Directions and Opportunities

“…Many techniques have been used for energy harvesting and energy-efficient methods discussed in [121]. Regarding energy-saving methods, Wang et al [122] proposed a resource allocation approach for minimizing the network's energy rate. Maximizing the power-efficiency was by relay station with subcarrier for an orthogonal frequency division multiple access.…”