Graphics-based And Math-based Resource Allocation Strategies For Wireless Powered Communication Networks

Following the rapid deployment of fifth-generation wireless systems,the number of wireless devices connected to the Internet of Things has explosively increased.However,wireless devices are characterized by their small size and limited battery capacity,hindering their ability to access power sources or enable frequent battery replacement.One potential solution to this problem is wireless powered communication networks(WPCN).WPCNs are based on the characteristics of RF corresponding to the insensitiveness to environmental fluctuations and the possibility of prolonging the system’s lifetime,where the EH receiver uses the power harvested in the downlink to transmit its information in the uplink.This dissertation firstly proposes a novel graphics-based multi-epoch power adjustment(GB-MBA)strategy based on an "energy tunnel" to maximize the sum-throughput.The time-switching factor and transmission power allocation are realized by integrating with alternate optimization algorithm.Compared with the interior point method,the simulations show that the computational complexity of the GB-MBA strategy is significantly reduced and prove the compatibility between the GB-MBA strategy and the alternating optimization algorithm.Then,a cooperative relay node is introduced into the conventional WPCN system,where user nodes and relay node work in a time division multiple access way.Due to the difficulty in implementing a graphics-based method,a math-based energy-efficiency oriented strategy is proposed to jointly optimize time-switching factor and transmission power.The simulations verify the convergence of the proposed strategy.The energy efficiency difference between the proposed math-based strategy and the benchmarks is also compared.Besides,the relay node is introduced to combat the doubly-near-far phenomenon,we propose a sum-throughput oriented resource allocation strategy to analyze the impacts of WPCN with relay or without relay on sum-throughput.The simulations prove that WPCN with relay outperforms the WPCN without relay.