Cooperative Multicasting in Renewable Energy Enhanced Relay Networks-Expending More Power to Save Energy

• Published in: IEEE transactions on wireless communications Vol. 15; no. 1; pp. 753 - 768
• Main Authors: Shi-Yong Lee, Chia-Yu Liu, Min-Kuan Chang, De-Nian Yang, Hong, Y.-W Peter
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Approximation methods; Arrivals; cooperative relaying; Energy conservation; Energy consumption; Energy costs; Energy harvesting; green communications; Mathematical analysis; multicast; Multicast communication; Power control; Power demand; Relay; Relays; Renewable energy; Renewable energy sources; Renewable resources; Wireless communication; cooperative relaying; power control; green communications; Energy harvesting; multicast
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2015.2477903

Power and on-off control problems are examined for renewable energy enabled base-stations (BSs) and relay nodes (RNs) in cooperative multicast networks. Renewable energy is utilized at BSs and RNs to reduce the overall grid energy cost. By considering a practical energy consumption model and the statistics of the renewable energy arrival, the optimal transmit powers are first determined by minimizing the expected grid energy consumption subject to an average outage probability constraint at MUs. The optimal solution is found via line search in the general case and is obtained in closed-form at high SNR. In addition, an on-off control policy is also proposed to further reduce the basic operational energy costs. The joint on-off and power control problems are solved approximately using two sequential deflation techniques, namely, the subset-search and the convex-relaxation-based approaches. The power control problem is also extended to the multicarrier scenario with unequal transmit powers and is solved using successive convex approximation. Simulations using the photovoltaic energy arrival model are provided to demonstrate the effectiveness of the proposed schemes. The results show that expending more power at RNs allows for more efficient use of renewable energy and, thus, increases energy-savings.