Massive Wireless Energy Transfer with Statistical CSI Beamforming

IEEE Access

Massive multiple-input multiple output (MIMO) systems have been introduced as a resolution for next generation cellular systems. The complexity of computing the precoding in massive MIMO is increased. So, studying a scalable precoding in massive MIMO system is a challenge task. In this paper, we propose a scalable precoder based polynomial for multiuser massive MIMO system, where base station (BS) is equipped with antennas that simultaneously communicate user equipments (UEs). This precoder applies matrix polynomial instead of matrix inversion. An energy efficiency (EE) optimization problem is formulated. This paper also studies optimal design parameters, which are the optimal transmit power, active UEs and number of antennas at BS. Mathematical formula for the EE-maximizing parameter estimations was mathematically analyzed with different orders of polynomial precoder. The impact of increasing polynomial orders is studied on the system performance. Comparison between proposed precoding technique and conventional techniques (i.e., zero forcing (ZF) precoder, minimum mean square error (MMSE) precoder and linear precoder) is provided. Results have shown that maximal EE and area throughput are achieved by deploying polynomial precoder in multiuser massive MIMO system. It can achieve better performance compared with conventional techniques. Utilization of polynomial precoder enhances the performance and provides high EE values.

IET Communications, 2017

Massive multiple-input multiple-output (MIMO) transmission/reception is a very promising enabling technique for future cellular systems. The performance of massive MIMO systems relies on the availability of channel state information (CSI) at the transmitter. However, due to estimation errors and delay this CSI is imperfect. Additionally, the use of many radio frequency (RF) chains to drive a large number of antennas at the transmitter quickly becomes impractical when that number increases. Thus, reducing the number of RF chains in massive MIMO systems is essential in order to reduce the system complexity and cost. Considering a massive MIMO system with a single-RF-chain transmitter, in this study, the authors design a precoding technique that is robust to the channel uncertainty. To reflect realistic restrictions in the authors' design, they consider the peak total transmitted power rather than the average power constraint. Also, they consider imperfect CSI and model the uncertainty region as a bounded one, which is a reasonable assumption. In this transmitter structure, there is only one power amplifier and load modulation rather than voltage modulation is used to generate the desired signals on the antenna elements. They demonstrate that when a very simple fixed equaliser is used at all user terminals, the problem of minimising the meansquare error of the received signals at user terminals under the worst-case channel uncertainty can be transformed into a convex optimisation problem. They provide simulation results and demonstrate that the proposed robust precoding technique outperforms non-robust techniques in terms of power efficiency and signal-to-interference-plus-noise ratios.

2014

Large-scale MIMO systems have been considered as one of the possible candidates for the next-generation wireless communication technique, due to their potential to provide significant higher throughput than conventional wireless systems. For such systems, Zero-Forcing (ZF) and Conjugate Beamforming (CB) precoding have been considered as two possible practical spatial multiplexing techniques, and their average achievable sum rates have been derived on the sum power constraint. However, in practice, the transmitting power at a base station is constrained under each antenna. In this case, the optimal power allocation is a very difficult problem. In this paper, the suboptimal power allocation methods for both ZF-based and CB-based precoding in large-scale MIMO systems under per-antenna constraint are investigated, which could provide useful references for practice.

Journal of Communications

Massive Multiple-input and Multiple-output (MIMO) is considered as a solution to the next generation cellular systems. It is visualized to provide extensive upgrade in capacity, along with the computational complexity as well as hardware. The main drawback of massive MIMO is the computational complexity in pre-coding, particularly when the "relative antenna-efficient Regularized Zero-Forcing (RZF)" is chosen to simplify Maximum Ratio Transmission (MRT). In this work, we propose to use the beam-forming methods, especially a hybrid pre-coding to reduce the system complexity in Massive MIMO. However, not only the system complexity, but also the computational complexity in pre-coding is the significant issue. In this regard, we propose another technique called Truncated Polynomial Expansion (TPE) pre-coding. It can emulate the same advantages of RZF, while offering the lower and extensible computational complexity that is achievable in an efficient pipelined fashion. By using random matrix theory, we can derive a closed-form expression of the SINR under TPE pre-coding. The proposed scheme is executed in an ideal Rayleigh fading channels, so that it produces highly desirable performance. Finally, we compare the results achieved from our proposed TPE pre-coding using three lower orders with RZF under various Channel State Information (CSI). It is obvious that our proposed method can provide the closest match to RZF, while the computational complexity is lower.  Index Terms-Massive MIMO, Zero-Forcing (ZF) pre-coding, RZF I. INTRODUCTION Wireless communication is defined as "the transmission of information over a distance without the help of wires, cables or any other forms of electrical conductors." The sender sends the signals through a device that has a capacity to generate electromagnetic signals to the receiver. There are various communication platforms such as Satellite, Mobile, Wireless network, Infrared and Bluetooth Communications. The main objective of all these platforms is to provide the high data rates. This desire for higher data rates leads the telecommunication engineers to implement new technology, such as the 5 th Generation Mobile communication Technology. The invention of 5G has enhanced the coverage, signaling & spectral efficiency [1], [2]. There are Manuscript

2012 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2012

We consider downlink cellular multi-user communication between a base station (BS) having N antennas and M single-antenna users, i.e., an N × M Gaussian Broadcast Channel (GBC). Under an average only total transmit power constraint (APC), large antenna arrays at the BS (having tens to a few hundred antennas) have been recently shown to achieve remarkable multi-user interference (MUI) suppression with simple precoding techniques. However, building large arrays in practice, would require cheap/power-efficient Radio-Frequency(RF) electronic components. The type of transmitted signal that facilitates the use of most power-efficient RF components is a constant envelope (CE) signal (i.e., the amplitude of the signal transmitted from each antenna is constant for every channel use and every channel realization). Under certain mild channel conditions (including i.i.d. fading), we analytically show that, even under the stringent per-antenna CE transmission constraint (compared to APC), MUI suppression can still be achieved with large antenna arrays. Our analysis also reveals that, with a fixed M and increasing N , the total transmitted power can be reduced while maintaining a constant signal-to-interference-noise-ratio (SINR) level at each user. We also propose a novel low-complexity CE precoding scheme, using which, we confirm our analytical observations for the i.i.d. Rayleigh fading channel, through Monte-Carlo simulations. Simulation of the information sum-rate under the per-antenna CE constraint, shows that, for a fixed M and a fixed desired sum-rate, the required total transmit power decreases linearly with increasing N , i.e., an O(N ) array power gain. Also, in terms of the total transmit power required to achieve a fixed desired information sum-rate, despite the stringent per-antenna CE constraint, the proposed CE precoding scheme performs close to the GBC sum-capacity (under APC) achieving scheme.

2017

We introduce a class of nonlinear least square error precoders with a general penalty function for multiuser massive MIMO systems. The generality of the penalty function allows us to consider several hardware limitations including transmitters with a predefined constellation and restricted number of active antennas. The large-system performance is then investigated via the replica method under the assumption of replica symmetry. It is shown that the least square precoders exhibit the "marginal decoupling property" meaning that the marginal distributions of all precoded symbols converge to a deterministic distribution. As a result, the asymptotic performance of the precoders is described by an equivalent single-user system. To address some applications of the results, we further study the asymptotic performance of the precoders when both the peak-to-average power ratio and number of active transmit antennas are constrained. Our numerical investigations show that for a desir...

Progress In Electromagnetics Research M

Energy-efficient transmission is fast becoming a critical factor in designing future mobile broadband cellular communication systems. This research work examines the constraints with regard to the achievable throughput and energy efficiency that can be attained on the use of precoding-based massive MIMO systems, bearing in mind the effect of some key performance impacting parameters. We first introduced an absolute energy efficiency-based model to evaluate the deep-down relationship among the packet length, the Bit error rate (BER) and throughput. Then, by means of simulation with cyclic coordinated search algorithm, optimal achievable throughput and energy efficiency performance have been shown and demonstrated for variable capacity of users and number of transmission antennas. This work is expected to be of enormous importance to practical system design on the use of massive MIMO antenna technology for data throughput and energy efficiency maximization in future 5G systems.

Wireless Communications and Mobile Computing

Massive multiple-input multiple-output or massive MIMO system has great potential for 5th generation (5G) wireless communication systems as it is capable of providing game-changing enhancements in area throughput and energy efficiency (EE). This work proposes a realistic and practically implementable EE model for massive MIMO systems while a general and canonical system model is used for single-cell scenario. Linear processing schemes are used for detection and precoding, i.e., minimum mean squared error (MMSE), zero-forcing (ZF), and maximum ratio transmission (MRT/MRC). Moreover, a power dissipation model is proposed that considers overall power consumption in uplink and downlink communications. The proposed model includes the total power consumed by power amplifier and circuit components at the base station (BS) and single antenna user equipment (UE). An optimal number of BS antennas to serve total UEs and the overall transmitted power are also computed. The simulation results co...

IEEE Transactions on Signal Processing, 2000

The problem of energy-efficient precoding is investigated when the terminals in the system are equipped with multiple antennas. Considering static and fast-fading multiple-input multiple-output (MIMO) channels, the energy-efficiency is defined as the transmission rate to power ratio and shown to be maximized at low transmit power. The most interesting case is the one of slow fading MIMO channels. For this type of channels, the optimal precoding scheme is generally not trivial. Furthermore, using all the available transmit power is not always optimal in the sense of energy-efficiency (which, in this case, corresponds to the communication-theoretic definition of the goodput-to-power (GPR) ratio). Finding the optimal precoding matrices is shown to be a new open problem and is solved in several special cases: 1. when there is only one receive antenna; 2. in the low or high signal-to-noise ratio regime; 3. when uniform power allocation and the regime of large numbers of antennas are assumed. A complete numerical analysis is provided to illustrate the derived results and stated conjectures. In particular, the impact of the number of antennas on the energy-efficiency is assessed and shown to be significant.

2020

1Assistant Professor,2,3,4UG Scholar, 1,2,3,4Department of Electronics and Communication Engineering, Hindusthan College of Engineering and Technology, Otthakalmandapam, Coimbatore, India. Email id : [email protected] ---------------------------------------------------------------------***--------------------------------------------------------------------Abstract Massive multiple-input multiple-output (MIMO) is one of the central technologies in the emerging 5G (Fifthgeneration wireless) systems, but also a concept applicable to other wireless systems. Utilization of the large number of degrees of freedom in massive MIMO essential for achieving high spectral efficiency, high data rates and extreme spatial multiplexing of densely distributed users. The benefits of applying massive MIMO for communication are well known and there has been a large body of research on designing communication schemes to support high rates. On the other hand, using massive MIMO for Internetof-Thi...