Joint Selection of On/Off Relay Mode and Adaptive Modulation Mode for Green Cooperative Multicast Networks

Increasing concerns about climate change are generating significant interest among researchers in reducing the energy consumption of existing communication infrastructure. However, previous research into the efficiency of cooperative communication networks only considers throughput or energy consumption separately. In response, this paper explores the trade-off between these two important factors and proposes maximizing energy efficiency, defined as the ratio of throughput over energy consumption. Because recent research demonstrates that machine operations require more energy, we propose opti- mally switching off unnecessary relays, while efficiently exploiting adaptive modulation (AM) to ensure that all multicast users can be served simultaneously under a required bit error rate. However, finding the optimal on/off relay mode and AM mode is challenging due to numerous possibilities required to be carefully considered and examined. To address this issue, we design an energy efficiency-aware search algorithm (EESA) to find the optimal solution. Our simulation results demonstrate that EESA is able to effectively improve the energy efficiency in cooperative multicast networks.