Abstract-Green energy is emerging as a promising alternative energy source to power network devices in next-generation wireless networks. Different from traditional energy, green energy is replenished from nature, e.g., solar and wind, and is highly dependent on the capacities and locations of the electronic devices. As such, the fundamental design criterion in the network deployment and management is shifted from energy efficiency to energy sustainability due to the sustainable nature of green energy. In this paper, we study the network resource management issues in next-generation wireless networks with sustainable energy supply. Our objective is to deploy the minimal number of green RNs, i.e., RNs powered by green energy, and optimize resource allocation to ensure full network connectivity and users' Quality of Service (QoS) requirements can be fulfilled with the harvested energy based on the cost threshold. To this end, the RN placement and sub-carrier allocation (RNP-SA) issues are jointly formulated into a mixed integer non-linear programming problem. Two low-complexity heuristic algorithms, namely RNP-SA with top-down/bottom-up algorithms (RNP-SAt/b), are presented to solve the non-linear programming problem in different network scenarios. Extensive simulations show that the proposed algorithms provide simple yet efficient solutions and offer important guidelines on network deployment and resource management in a green radio network with sustainable energy sources.Index Terms-Wireless communication networks, sustainable energy, relay node placement, sub-carrier allocation.

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This paper presents a new systematic design and optimization procedure used for the microgrippers driven by a chevron electrothermal actuator. The procedure includes three steps: first, a suitable rigid-body gripper mechanism is selected using the type synthesis of the kinematic chain method; then, the rigid-body mechanism is transferred into a compliant microgripper; finally, by the stiffness matrix model and the genetic algorithm, a geometry parametric optimization with the high output stiffness objective is carried out. Using this procedure, a novel SU-8 electrothermal microgripper is obtained. According to the FEM simulation, the microgripper meets the design requirements and satisfies the constraints. To eliminate the out-of-plane actuation, a novel processing technology is implemented to fabricate the microgripper with a sandwich structure actuator. The experimental results demonstrate that a jaw gap change of 107.5 µm requires only 73.6 mV, 25.61 mW and only 44.92 °C temperature increase at the actuator and the out-of-plane actuation is almost eliminated. A micromanipulation of a micro blood vessel specimen and a micro-assembly for micro-tensile testing studies of fine hair are demonstrated. Hence, the design procedure is valid to generate novel compliant micro mechanisms. The fabrication process can be used in the fabrication of other SU-8 MEMS devices actuated by the electrothermal actuator.