Research On MIMO And Intelligent Reflective Surface Transceiver Mechanism And Algorithms For Data And Energy Integrated Transfer

Tele-traffic is expected to continue exponential growth in 6G of communication systems,which is partially attributed to ultra-high throughput of multi-media transmissions such as virtual reality and augmented reality,and partially attributed to massively deployed low-power Internet of Everythings(IoE)devices for communications in wearable medical applications and environments monitoring.However,quickly drained batteries largely limit performance of IoE devices.Therefore,radio frequency(RF)signals are relied upon for transferring wireless power to these devices in far-field.Coordinating wireless data transfer(WDT)and wireless energy transfer(WET)in the same RF band has been envisioned as a key enabling technique named data and energy integrated transfer(DEIT)for the sake of simultaneously satisfying both the information requirements of data users and the charging requirements of energy users.For the sake of counteracting the channel attenuation,multiple-input-multiple-output(MIMO)and intelligent reflecting surface(IRS)have been exploited for providing substantial spatial gains in DEIT system.An IRS is composed of a large number of low-cost reflecting elements,each of which is capable of passively reflecting RF signals by adjusting their phases in the analog domain.Therefore,the resultant passive beam aims at receivers,which may substantially improve wireless communication performance by exploiting additional spatial gains.In order to adapt to various scenarios of WDT and WPT requirements in 6G communication,MIMO and IRS-assisted DEIT systems is studied in various frequency bands and demonstrate the advance of our design in both WDT and WET performance.Firstly,at Sub-6G frequency which is from 450 MHz to 6000 MHz,the IRS aided MIMO wireless energy transmission system is studied,and then the IRS aided single-user WET system is extended to the IRS aided multi-user DEIT system.Moreover,the massive MIMO multi-user DEIT system is studied in the millimeter wave frequency band.Finally,massive MIMO-IRS multiuser DEIT in the Tera-Hertz(THz)frequency band system is investigated.The four main research contents of this dissertation are:In the first part,an IRS aided WET system is investigated,while a practical architecture of an energy user is proposed,which includes multiple receive antennas,an analog power combiner,a power splitter and multiple energy harvesters.In order to maximize the output direct-current(DC)power,the transmit beamformer of the transmitter,the reflecting beamformer of the IRS,the power combiner,and the power splitter of the energy user are jointly optimized.The optimization problem is equivalently divided into two sub-problems,which independently maximizes the input RF power and the output DC power of the energy harvesters,respectively.A successive linear approximation based algorithm with a low complexity is proposed to maximize the input RF power to the energy harvesters.An improved greedy randomized adaptive search procedure based algorithm having better performance to maximize the input RF power is alsp proposed.Furthermore,the optimal power splitter for maximizing the output DC power of the energy harvesters is derived in closed-form.The numerical results demonstrate that our improved greedy randomized adaptive search procedure based algorithm achieves better performance than the counterpart,while successive linear approximation based algorithm has the lowest complexity.Then,a robust beamforming design for an IRS-aided DEIT with imperfect channel state information(CSI)is considered.Against the uncertain channel estimation error,the transmit beamformers of the transmitter and the passive reflecting beamformer of the IRS are robustly designed to minimize the transmit power by satisfying both the WDT and WET requirements.A successive target migration optimization algorithm is proposed to obtain a robust design.The transmit covariance matrices are optimized by relaxing rank-one constraints,when a passive reflecting beamformer is given.Then,the target to minimize the transmit power is migrated to maximize the QoS requirements of energy users due to the fixed transmit power.A local optimal reflecting beamformer is obtained for improving the attainable WET performance,when the transmit covariance matrices are given.Finally,It is proved that the rank-one transmit beamformers can always be found,which have the same WET and WDT performance as the transmit covariance matrices.The numerical results demonstrate that transmit power of the IRS aided system reduce 43%compared to the no IRS counterpart,while our robust design is capable of against the channel uncertainty.Further,transceiver design in a multi-user millimeter wave massive MIMO system for DEIT is investigated.By jointly designing the hybrid beamformer at the transmitter and combiners of data and energy users,the multicast spectrum efficiency is maximized while satisfying the energy needs of energy users.According to the statistical characteristics of the millimeter wave channel,the full-digital beamformer,full-digital combiner of data users,and analog receiver combining for energy users are obtained in closed-form,while they achieve asymptotically optimal performance.Hybrid beamformer is obtained by approaching full-digital beamformers.A low complexity one-dimensional search algorithm is proposed to dynamically adjust full-digital beamformer so that the corresponding hybrid beamformer maximizes the multicast spectrum efficiency while satisfying energy supply requirements.The numerical results verify the performance advantages in both WDT and WET.At last,a IRS aided THz massive MIMO multi-user DEIT system is explored.Firstly,the sparsity and angular orthogonality of the THz channel are analyzed.In the singleuser and multi-user THz communication systems,the solution of asymptotically optimal analog beamformer is obtained in closed-form,and the asymptotically optimal digital beamformer is obtained by solving a linear programming.Moreover,the asymptotically optimal reflecting beamformer is derived in closed-form when an IRS aided multi-user communication in THz bands system is investigated.Furthermore,the IRS-based THz massive MIMO multi-user DEIT system is studied.The asymptotically optimal analog beamformer and receiver combining is obtained in closed-form,and the asymptotically optimal structure of digital beamformer and reflective beamformer is obtained.By analyzing the necessary conditions of the optimal solution,a low complexity one-dimensional search algorithm is proposed to obtain digital beamformer and reflective beamformer.Numerical results show that the performance of proposed hybrid beamformer and reflecting beamformer is very close to that of full-digital optimal counterpart.The dissertation investigates the IRS-MIMO DEIT system.In various frequency,the transiver design algorithms are proposed for WDT and WET requirements,which provides the theoretical basis for the application of IRS-MIMO DEIT in the future 6G.