Joint Resource Allocation For Simultaneous Wireless Information And Energy Transfer In Wireless Relay Networks

Simultaneous wireless information and power transfer(SWIPT)has attracted worldwide research interests.It enables energy harvesting(EH)through radio frequency(RF)signals,thus offering inexhaustible energy supplies to terminals,and make it possible for extending the lifetime of energy constrained networks.In wireless relay networks,relay nodes with EH capability can assist the other nodes transfer their data in a passive way,which offsets their unwillingness to deplete energy reserves as they did in cooperative communications.In the paper,based on the characteristics of wireless relay network with SWIPT we elaborate on network resources optimization and allocation.We study network throughput control strategy in single user network with time switching(TS)scheme,source energy efficiency optimization method and put forward to multi-variable dual algorithm to solve maximization network throughput problem in multi-user network with power splitting(PS)scheme,respectively.Firstly,by considering the circuit power consumption at the relay node R,the joint resource allocation problem can be formulated as the network throughput maximization under constraints such as the time switching,transmission power uses at nodes in SWIPT relay networks with TS scheme.Based on the coupling relationship between the optimization variables,the optimal variables can be fixed sequentially.The optimal power allocation for energy transmission can be obtained at first,and then the integrated problem that includes time switching factors and power allocation for energy transmission can then be separated into a convex sub-problem and a non-convex sub-problem,the latter of which can be solved by using the nonlinear genetic algorithm.The simulation results show the feasibility and superiority of the proposed algorithm.Then,from the perspective of energy consumption for energy providers in the wireless relay network with SWIPT,the paper investigates the source energy consumption minimization problem.To facilitate finding the optimal solution,we transform the problem to an equivalent convex problem.Before giving the optimal solution to the convex problem,a feasibility assessment problem is then developed to check its feasibility.We then propose a unified optimization framework,in which boththe result about the feasibility assessment problem and the optimal solution(if it exists)to the considered resource configuration problem can be obtained simultaneously,leading to a much less cost of computational complexity.Simulations results reveal that the proposed unified framework is effective in minimizing energy consumption,meeting QoS requirement,and realizing optimal resource configuration.Finally,the joint resource allocation problem is formulated to maximize the throughput while satisfying data rate requirements for multiuser SWIPT relay networks with PS scheme.The analytical expression of power splitting ratio can be deduced and can be reached its global optimum.The remaining two sub-problems,i.e.,power allocation and subcarrier pairing allocation can then be reformulated as two relatively independent problems and solved in their dual domain.Simulation results further validate the better performances of our proposed algorithm.