Modulation And Coding Design For Simultaneous Wireless Information And Power Transfer

With the development of wireless communications,more and more devices are connecting into the network,including some common devices,such as mobile phones,laptops,tablets,as well as some micro-devices in Internet of Things(Io T),such as wireless sensors,which brings the bottleneck for the energy supplyment in the future networks.Artificially charging or replacing batteries for these devices is not worth the candle.Therefore,meeting the energy requirements for these plenty devices is becoming a key challenge in the future.Inspired by the sustainable development,it could be an approach to enable the devices to glean ambient energy,such as solar energy,wind energy and mechanical energy,which could guarantee the energy supplyment of them.However,the frequent changes of surroundings always constrains the performance of energy harvesting and then reduces the controllability of the network,which prompts the born of the concept of wireless power transfer(WPT).Thanks to the fact that electromagnetic waves always carries energy,it's becoming possible to enable devices to harvest the energy of radio-frequency(RF)signals.Compared with some other existing technologies of WPT such as inductive coupling and magnetic coupling,RF energy transfer provides a larger coverage,which is more suitable for wireless communication networks.Simultaneous wireless information and power transfer(SWIPT)enables a transmitter to transfer data information at the same time it transfers RF energy,which could meet both the requirements of data communication and energy supplyment of connected devices.In recent years,there are plenty of works studying SWIPT,while a majority of them focuses on the resource allocation in the media access control(MAC)layer.Classic Shannon-Hartley channel capacity is considered for measuring the performance of wireless information transfer(WIT),which is far from practice.Therefore,this dissertation focuses on the modulation and coding design for SWIPT,which aims to adjust the waveform of RF signals in the physical layer and then affect the performance of WPT and WIT basically.The dissertation is divided into four chapters: 1)Unary coding aided information and energy coding design for SWIPT;2)Time index modulation design for SWIPT;3)Receive spatial modulation design for SWIPT;4)Joint modulation design for multi-user SWIPT NOMA.In the first part,a novel transceiver architecture for SWIPT is designed,where a unary coding aided information and energy coding module is added before traditional modulation,in order to cope with the problem that traditional source and channel coding always outputs codewords having regular and equivalent distribution.Based on classic Markov modelling approach,the transmission probability of both the codewords and the modulated symbols are obtained to analyse the energy harvesting amount and the bit error ratio(BER)at the receiver theoretically.Then,a genetic algorithm is proposed to optimize the unary coding aided codeword distribution as well as the power splitting ratio,in order to maximizing the WPT performance by guaranteeing the WIT performance.Simulation results demonstrate that by introducing the additional information and energy coding,the system becomes more flexible to adjust the performance of WPT and WIT dynamically.Further,this dissertation focus on the modulation design for SWIPT.Index modulation enables additional information to be transmitted on the index dimension,which increases the spectrum efficiency in the crowded wireless networks.Inspired by the traditional time switching approach for dividing WIT and WPT,this dissertation proposes a time index modulation(TIM)based system for SWIPT,where the transmitter selects a time slot in a period for transmitting conventional modulated symbols according to the time index data information,while other times slots serve for WPT.Then,the average energy harvesting amount and approximate BER at the receiver are analysed theoretically,which is validated by the Monte-Carlo simulation.After the optimization,the transmit power of data signal and energy signal are obtained,in order to make a trade-off between WIT and WPT performance.Simulation results demonstrate that compared with traditional time switching approach,TIM could increase both the data rate and the energy harvesting amount at the receiver.Similar with the last chapter,this dissertation proposes a receive spatial modulation(RSM)architecture for multiple input multiple output(MIMO)SWIPT systems,where the additional information is carried on the index of the activiated data receive antennas.With the aided of zero-forcing technique,the low-power receiver could save more energy by abandoning additional signal processing operation.Then,three different schemes,i.e.General Scheme,Superimposed Scheme and Distinct Scheme,are proposed in order to meets various WIT and WPT performance requirements.With the aid of theoretical analysis,the BER as well as the energy harvesting amount at the receiver are obtained,which are also validated by the Monte-Carlo simulation.Simulation results demonstrate that compared with traditional MIMO system without spatial modulation,RSM could enhance the data rate by guaranteeing the same WPT performance.Moreover,distinct scheme outperforms other schemes in both data information and energy transfer dimensions.At last,a multi-user SWIPT scenario is studied,where non-orthogonal multiple access(NOMA)technology is considered for the sake of increasing the network spectrum efficiency.The superposition of multi-users' symbols having distinct phases may cause signal offset,which is unfavorable for WPT.In order to cope with this problem,this dissertation proposes a joint modulation scheme by considering energy interleaving among multiple sub-carriers and constellation rotation on a single sub-carrier.Moreover,an efficient power allocation scheme is also proposed,in order to constrain the signal distortion caused by multi-users' signal superposition and further guarantee the symbol error ratio(SER)after the demodulation using successive interference cancellation(SIC)technique.Simulation results demonstrate that the energy harvesting performance is efficiently increased by adopting the joint modulation scheme,while the WIT performance of SER is also guaranteed.