In this paper, we survey state-of-the-art research outcomes in the burgeoning field of Reconfigurable Intelligent Surface (RIS), given its potential for significant performance enhancement next-generation wireless communication networks by means adapting a propagation environment. Emphasis has been placed on several aspects gating commercial viability future network deployment. Comprehensive summaries are provided practical hardware design considerations and broad implications artificial...

Current trends in wireless communications require a Base Transceiver Station (BTS) to support an ever-increasing number of antennas, wider bandwidths, multiple frequency bands, and many simultaneous beams. This is tall order when considering all-electronic implementations, especially operating at high carrier frequencies. We describe here Fourier-optics based opto-electronic architectures that include analog fully connected transmit (TX) receive (RX) implementations multi-band, multi-beam...

We extend the lattice-reduction (LR) method to MIMO detection for coded space division multiplexing OFDM systems with soft-input decoding. The scheme employs a novel combination of LR, K-best candidate generation, and simple pruning. With handful candidates, receiver is able approach packet error rate performance full maximum likelihood detector within 1 dB, over varying data rates channel correlations. It appealing high-rate coded-MIMO operating quasi-static wireless channels, where...

For low-resolution analog-to-digital converter (ADC) systems, only high-complexity receive antenna selection has been developed and transmit limited to a single in prior work. In this paper, we propose low-complexity algorithms analyze by considering at base station with large arrays ADCs. downlink selection, show criterion zero-forcing precoding equivalent perfect quantization system; sum rate increases number of selected antennas; derivation the loss function from using subset; reaches...

A tapered fiber-slab waveguide coupler (TFSC) is proposed in this paper. Both the numerical analysis based on beam propagation method and experiments are used for investigating dependencies of TFSC transmission features their geometric parameters. From simulations experimental results, rules fabricating a with low loss sharp resonant spectra by optimizing configuration parameters presented. The conclusions derived from our work may provide helpful references optimally designing TFSC-based...

In this paper, we consider the feedback and precoding designs for massive multiple-input multiple-output (MIMO) systems. Based on a recently introduced two-stage beamforming framework, termed as joint spatial division multiplexing (JSDM), propose generalized JSDM approach to deal with practical issue that user's channel usually has multiple scattering clusters mobile broadband which may incur significant performance degradation original JSDM. particular, new where users feed back additional...

We consider the problem of jointly optimizing ADC bit resolution and analog beamforming over a frequency-selective massive MIMO uplink. build upon popular model to incorporate impact low ADCs, that hitherto has mostly been employed flat-fading systems. adopt weighted sum rate (WSR) as our objective show WSR maximization under finite buffer limits important practical constraints on choices beams resolutions can equivalently be posed constrained submodular set function maximization. This...

A novel technique for generating RF sources mobile communications based on dual Mach–Zehnder modulators and high-power charge-compensated modified unitraveling carrier (CC-MUTC) photodiodes is presented. system model developed used to establish mitigate nonlinearities attributed its constituent components, i.e., waveform generators, amplifiers, modulators, photodiodes. In particular, digital predistortion improve source linearity. Extensive experiments are conducted characterize the proposed...

We present an RF-photonic phased-array receiver that provides simultaneous multi-band and multi-beam operation in the millimeter-wave region of spectrum. It uses a photonic integrated circuit to perform RF beamforming with near unlimited beam-bandwidth product.

We present the use of a novel optical modulator architecture to achieve simultaneous radiofrequency (RF) multi-user beamforming and data modulation. Optical vector modulators enable control complex state transmitted wave by directly independently controlling both amplitude phase. Operating in domain affords extremely wide bandwidth negligible dispersion such modulators. A demonstration experiment is presented based on 2-element transmit array, where were assembled from pairs commercial phase...

When we have knowledge of the positions nearby walls and buildings, estimating source location becomes a very efficient way characterizing radio channel. We consider localization performance with without this wall knowledge. treat multipath channel as set 'virtual receivers' whose can be pre-stored in database. Using knowledge, develop direct positioning MUSIC algorithm that treats reflection parameter nuisance variable. compare to classic MVDR lacks In simple scenario, find lack increase...

In this paper, we survey state-of-the-art research outcomes in the burgeoning field of reconfigurable intelligent surface (RIS) view its potential for significant performance enhancement next generation wireless communication networks by means adapting propagation environment. Emphasis has been placed on several aspects gating commercially viability a future network deployment. Comprehensive summaries are provided practical hardware design considerations and broad implications artificial...

Traditionally intelligent reflecting surface (IRS) has been viewed as an ideal passive phase shifter with no mutually coupled elements. For this assumption to hold, IRS inter element spacing needs be at least Nyquist spacing, thereby increasing overall aperture size number of In paper, we consider reverse problem wherein the is fixed. Here, packing more elements in a given space enhance system performance results mutual coupling and correlated fading. We aided communication network for...

In this paper, a novel all-fiber electric field sensor based on tapered fiber-slab waveguide coupler was proposed for the first time. Experiments were implemented investigating dependences of TFSC transmission features their geometries parameters. On base that with optimal construction parameters and sharper coupling spectra fabricated. The nearly linear relationship between changes outputs external applied are demonstrated by experiments. minimal detectable has also been experimentally to...

Phased antenna arrays have been used extensively for massive MIMO-based multiuser beamforming to improve both the throughput and power efficiency of wireless communication systems. Beamforming can be realized by Butler matrix, which has demonstrated in electric domain. With systems migration toward simplified remote radio units through radio-over-fiber sharing signal processing functions located central office, it is desirable implement this technique optical In paper, we propose an...

We propose a novel equivalent model for quantizer with noisy input (the desired signal corrupted by measurement noise). It presents the output as sum of after it passes through nonlinear element known transfer function and an additive white noise. The takes form conditional expectation given portion its input. proposed proves to be effective analysis design MIMO systems employing low-resolution quantizers (analog digital analog converters, ADCs DACs, respectively). also demonstrate efficacy...

Due to the low per-antenna SNR and high signaling overhead, channel estimation is a major bottleneck in Massive MIMO systems. Spatial constraints can improve performance by exploiting sparsity. Solutions exist for far field - beam domain based on angle of arrival estimation. However, there no equivalent solution near distributed spatial We present solution- source estimation- that location extend this employ "Channel Database" incorporating information about physical scattering environment...

Maintaining phase coherence in large phased arrays is challenging all-RF implementations, while alternatives based on optical signal conditioning require expensive phase-locked lasers. We present a novel transmit architecture for an optically-fed array where high ensured by using two inexpensive lasers operating at different wavelengths, representing the carrier and its local oscillator reference signal. Heterodyne detection via photomixing of signals ensures generation quality RF canceling...

We propose a location-domain channel representation and apply it to estimation for distributed MIMO (D-MIMO) networks. The approach contrasts with various angle-domain formulations that appear well suited collocated large array where the far-field assumption allows an but are ill-suited geographically arrays (large small), as in densely deployed 5G cellular Our alternative avoids such difficulties by indexing multipath locations, instead of angles, user terminals or access points....

In this paper, we consider the design of multiuser (MU) massive multiple-input and multiple-output (MIMO) employing hybrid beamforming, i.e., an analog radio frequency (RF) beamforming at front end concatenated with a digital baseband precoding. We present several RF beam feedback protocols small overhead, i.e. indices or without channel quality index (CQI). Based on schemes, novel algorithms to jointly select transmit beams schedule users improve system throughput. Specifically, when feed...

In this paper, we first define a high dimensional (HiDi) channel characteristics, i.e., space-frequency covariance, for wideband MIMO-OFDM systems. We then design the conversion of HiDi covariance in frequency domain from one carrier to another, e.g., FDD Specifically, apply projection method Hilbert space estimate power angle delay spectrum and form covariance. also obtain asymptotic solutions when considering infinite spread, which significantly reduces complexity. Moreover, generalize...

When a quantizer input signal is the sum of desired and white noise, quantization error function total signal. Our new equivalent model splits into two components: non-linear distortion (NLD) that only part (without noise), an out-put noise. This separation important because these terms affect MIMO system performance differently. paper introduces our model, applies it to determine minimal Analog-to-Digital Converter (ADC) resolution necessary operate conventional receiver with negligible...