Resource Allocation For Wireless Powered Non-orthogonal Multiple Access Networks

The wireless power transfer(WPT)is a controllable and promising way to solve the energy scarcity and replacing batteries problem of the wireless devices of wireless networks.The technology is controllable and satisfies the future communication development trend.WPT can be used in the wireless communication field.WPT technology has been applied to existing wireless multiple access techniques(e.g.FDMA,TDMA,OFDMA)in many researches.This application not only solves the energy shortage problem of mobile nodes but also promotes the development of wireless communication.Besides the energy scarcity problem,wireless communication also faces spectrum scarcity problem.With the increasing demand on high efficient spectrum usage,wireless multiple access technique is urgently needed.The non-orthogonal multiple access(NOMA)scheme is a new multiple access technique,which has been proposed to provide higher spectral efficiency(SE)and massive connectivities.Combining NOMA with WPT,not only can solve the battery power shortage and frequent battery replacement problems but also can improve the spectrum efficiency of wireless system,which is especially suitable for 5G networks that supports the massive sensor node access.In this thesis,we consider wireless powered non-orthogonal multiple access networks,which is consist of one multiple antenna power station,multiple single-antenna users and one single antenna information receiver.Since multiple users need to transmit their information to an information receiver in the NOMA manner,the users' limited energy and the limited spectrum can affect the transmission rate.In the considered system,downlink and uplink denote the physical channel from the power station to the users and from the users to information receiver respectively.The power station transmits the energy to the users by radio-frequency WPT in the downlink.The users use their harvested energy and transmit their information to the information receiver in the NOMA manner in the uplink.In this thesis,we first consider the caser the power station knows perfect channel state information(CSI).the throughput can be optimized by joint energy beamforming and resource allocation design,i.e.,jointly optimizing the energy beamforming at the power station,the transmit powers of the users,as well as the time allocation between downlink and uplink.However,In the actual application scenario,the power station obtains the only knows CSI.In this scenario,the CSI known by the power station contains error.We further consider the imperfect CSI case,and propose robust resource allocation scheme to maximize the throughput subject to additional outage probability constraints on the users.Furthermore,we consider the circuit power consumption of the power station and users,and investigate the system energy efficiency(EE)maximization resource allocation scheme subject to the Qo S requirement constraint.For the EE maximization problem,we transform the nonlinear fractional form of the objective function by using the Dinkelbach method.This allows us to designs joint energy beamforming,time allocation and transmit power of users design to maximize the EE problem.We propose an efficient iterative optimization algorithm to solve it.Simulation results show that the proposed algorithms achieve higher throughput than the benchmark schemes and the tradeoff between SE and EE,respectively.