Design And Performance Analysis Of Simultaneous Wireless Information And Power Transfer System

Recently,wireless energy transfer(WET)technology has drawn the considerable interest in wireless communication field.Wireless energy harvesting and transmission technology based on radio frequency(RF)has been one of the main energy harvesting methods for wireless energy-constrained devices in the wireless networks.Furthermore,the RF electromagnetic wave can also deliver information.So the signal design and processing technology based on the combination of wireless energy and information transmissions has been a new research hot point in wireless communication field.Meanwhile,due to some advantages of the chaotic signal,like non-periodic,randomness,wideband,etc.,chaotic communication technology has been used widely in the system signal design and processing.Especially,the differential chaotic digital modulation technology,not only has the simple circuit structure,but also has enhanced anti-multipath interference capacity.Thus,it is a very competitive technology in the low-power wireless communication applications.Considering the above reasons,for the low-power wireless communication network application,this article has studied design and performance analysis of simultaneous wireless information and power transfer(SWIPT)protocol in the RF-enabled multi-input single-output(MISO)system and multi-carrier differential chaos shift keying(MC-DCSK)system.The main works are as follows:(1)We introduce and summarize some RF-enabled models,such as wireless energy transfer(WET),SWIPT,wireless powered communication networks(WPCN),including their schematics and basic ideas,the advanced signal processing methods and the future extensions.On the basis of these technologies,we study the throughput optimization of the RF-enabled large-scale MISO SWIPT system.Firstly,a MISO SWIPT system model with power splitting receiver has been built.Considering the constraints of quality-of-service requirement of downlink and transmit power of mobile station,to maximize uplink throughput,a jointly optimizing the power splitting(PS)coefficient and energy transfer time duration based on the SWIPT protocol has been proposed.To resolve the non-convex optimization problem,the non-convex optimization problem is converted equivalently into the convex optimization problem.Then,the Lagrange multiplier is utilized to remove the constraints of the convex optimization problem and the iterative algorithm based on the gradient method is applied to solve the non-constraints optimization problem.Finally,the superiority of the proposed joint optimization scheme has been validated by simulation results.(2)Because of advantages of the differential chaotic digital modulation technology,we study the performance of SWIPT protocols in the multi-carriers DCSK system.A SWIPT MC-DCSK system model with a power splitting receiver has been built.With harvested energy constraints,two protocols are proposed.And the bit error ratio(BER)expressions of the information decoding receiver in the two protocols are derived.Then by minimizing bit error ratios of information decoding receiver,the optimal power allocation ratios on sub-carriers are obtained.Finally,we study the throughput and harvested energy of the two protocols with total transmitted power,bandwidth constraints and the according optimal sub-carrier power allocation ratio.