Showing papers on "Phase-shift keying published in 2018"

Generalized Multiple-Mode OFDM With Index Modulation

Abstract: Multiple-mode orthogonal frequency division multiplexing with index modulation (MM-OFDM-IM), which transmits an OFDM signal with information bits embedded onto multiple distinguishable signal constellations of the same cardinality and their permutations, is a recently proposed IM technique in the frequency domain. It is capable of achieving higher spectral efficiency and better error performance than classical OFDM and existing frequency-domain IM schemes. In this paper, we propose the scheme of generalized (G-) MM-OFDM-IM, which allows a different subcarrier to utilize a signal constellation of a different size while conveying the same number of IM bits. Considering phase shift keying constellations, we present design guidelines for GMM-OFDM-IM to achieve an optimal error performance in the asymptotically high signal-to-noise ratio region. A computationally efficient and near-optimal detector based on the idea of sequential decoding is also tailored to GMM-OFDM-IM, which avoids the detection of an illegitimate constellation permutation. Monte Carlo simulations are conducted to validate the inherent properties and advantages of GMM-OFDM-IM.

Wireless Communications with Programmable Metasurface: Transceiver Design and Experimental Results

Abstract: Metasurfaces have drawn significant attentions due to their superior capability in tailoring electromagnetic waves with a wide frequency range, from microwave to visible light. Recently, programmable metasurfaces have demonstrated the ability of manipulating the amplitude or phase of electromagnetic waves in a programmable manner in real time, which renders them especially appealing in the applications of wireless communications. To practically demonstrate the feasibility of programmable metasurfaces in future communication systems, in this paper, we design and realize a novel metasurface-based wireless communication system. By exploiting the dynamically controllable property of programmable metasurface, we firstly introduce the fundamental principle of the metasurface-based wireless communication system design. We then present the design, implementation and experimental evaluation of the proposed metasurface-based wireless communication system with a prototype, which realizes single carrier quadrature phase shift keying (QPSK) transmission over the air. In the developed prototype, the phase of the reflected electromagnetic wave of programmable metasurface is directly manipulated in real time according to the baseband control signal, which achieves 2.048 Mbps data transfer rate with video streaming transmission over the air. Experimental result is provided to compare the performance of the proposed metasurface-based architecture against the conventional one. With the slight increase of the transmit power by 5 dB, the same bit error rate (BER) performance can be achieved as the conventional system in the absence of channel coding. Such a result is encouraging considering that the metasurface-based system has the advantages of low hardware cost and simple structure, thus leading to a promising new architecture for wireless communications.

Parallelized Kalman Filters for Mitigation of the Excess Phase Noise of Fast Tunable Lasers in Coherent Optical Communication Systems

Abstract: Numerical and experimental investigations are carried out on the performance of parallelized Kalman filters applied for mitigation of the excess phase noise of fast tunable lasers. Based on the characterization of the phase noise of a sampled grating distributed Bragg reflector (SG-DBR) laser, the proposed carrier phase recovery (CPR) scheme using Kalman filters is introduced. By performing simulations of data transmission with various advanced modulation formats in the presence of the excess phase noise, the Kalman filter based CPR scheme shows its ability to overcome the excess phase noise and this method is suitable for parallel processing. Then the results are further demonstrated by 12.5 Gbaud QPSK and 16-QAM transmission experiments employing the SG-DBR laser. We find that the Kalman filters have better performance than the 2nd-order phase-locked loop in parallel systems due to a better phase noise tolerance. The bit error rate performance is also examined in the whole tuning range (∼30 nm) of the tunable laser, which further proves the feasibility of the proposed scheme.

100 Gbit/s THz Photonic Wireless Transmission in the 350-GHz Band With Extended Reach

Abstract: In this letter, we experimentally demonstrate terahertz (THz) photonic wireless transmission of high-speed quadrature-phase-shift-keying (QPSK) and 16 quadrature amplitude modulation (16-QAM) signals in the 350-GHz band, with an effort to extend the wireless reach of ultrafast 100 Gbit/s. In the experiment, a narrowband unitraveling-carrier photodiode (UTC-PD) is used for heterodyne generation of THz communication signals, which is transparent to optical modulation formats. Experimental results show that 30 GBd/s QPSK (60 Gbit/s) and 25 GBd/s 16-QAM signals (100 Gbit/s) are successfully transmitted over a 350-GHz wireless link with an extended distance of 2 m. This enhancement is enabled by combining the techniques of employing cutting-edge narrowband UTC-PD as the photomixing THz emitter, spectrally efficient modulation format and advanced digital signal processing algorithms. The achievement makes 100 Gbit/s THz wireless communication systems promising for future smart wireless services.

The Trade Off Between Different Modulation Schemes for Maximum Long Reach High Data Transmission Capacity Optical Orthogonal Frequency Division Multiplexing (OOFDM)

Abstract: This paper shows the trade off between different modulation techniques such as multi level quadrature amplitude modulation, multi level phase shift keying, and multi level differential phase shift keying for upgrading direct detection optical orthogonal frequency division multiplexing systems with possible transmission distance up to 15,000 km and total bit rate of 2.56 Tb/s. The 2.56 Tb/s signal is generated by multiplexing 64 OFDM signals with 40 Gb/s for each OFDM. Variations of optical signal to noise ratio (OSNR), signal to noise ratio (SNR), and bit error rate (BER) are studied with the variations of transmission distance. Maximum radio frequency power spectrum, and output electrical power after decoder are measured for different multi level modulation techniques with carrier frequency. It is observed that multi level QAM has presented better performance than multi level PSK and finally multi level DPSK in optical OFDM systems. Maximum output power after decoder is enhanced with both 32-PSK, and 64-QAM. Quadrature signal amplitude level at encoder is upgraded with 64-QAM. It is noticed that OSNR, SNR, and BER are improved using 4-QAM OFDM system than either QPSK or 4-DPSK.

Blind Nonlinearity Equalization by Machine-Learning-Based Clustering for Single- and Multichannel Coherent Optical OFDM

Abstract: Fiber-induced intra- and interchannel nonlinearities are experimentally tackled using blind nonlinear equalization (NLE) by unsupervised machine-learning-based clustering (MLC) in ∼46-Gb/s single-channel and ∼20-Gb/s (middle-channel) multichannel coherent multicarrier signals (orthogonal frequency-division multiplexing (OFDM) based). To that end, we introduce, for the first time, hierarchical and fuzzy-logic C -means (FLC)-based clustering in optical communications. It is shown that among the two proposed MLC algorithms, FLC reveals the highest performance at optimum launched optical powers (LOPs), while at very high LOPs, hierarchical can compensate more effectively nonlinearities only for low-level modulation formats. When employing binary phase-shift keying and quaternary phase-shift keying, FLC outperforms K-means, fast-Newton support vector machines, supervised artificial neural networks, and NLE with deterministic Volterra analysis. In particular, for the middle channel of a QPSK wavelength-division multiplexing coherent optical OFDM system at optimum −5 dBm of LOP and 3200 km of transmission, FLC outperforms Volterra-NLE by 2.5 dB in Q-factor. However, for a 16-QAM single-channel system at 2000 km, the performance benefit of FLC over inverse Volterra-series transfer function reduces to ∼0.4 dB at a LOP of 2 dBm (optimum). Even when using novel sophisticated clustering designs in 16 clusters, no more than additional ∼0.3-dB Q-factor enhancement is observed. Finally, in contrast to the deterministic Volterra-NLE, MLC algorithms can partially tackle the stochastic parametric noise amplification .

Symbol Error Rate Performance of Box-Relaxation Decoders in Massive MIMO

Abstract: The maximum-likelihood (ML) decoder for symbol detection in large multiple-input multiple-output wireless communication systems is typically computationally prohibitive. In this paper, we study a popular and practical alternative, namely the box-relaxation optimization (BRO) decoder, which is a natural convex relaxation of the ML. For independent identically distributed real Gaussian channels with additive Gaussian noise, we obtain exact asymptotic expressions for the symbol error rate (SER) of the BRO. The formulas are particularly simple, they yield useful insights, and they allow accurate comparisons to the matched-filter bound (MFB) and to linear decoders, such as zero-forcing and linear minimum mean square error. For binary phase-shift keying signals, the SER performance of the BRO is within 3 dB of the MFB for square systems, and it approaches the MFB as the number of receive antennas grows large compared to the number of transmit antennas. Our analysis further characterizes the empirical density function of the solution of the BRO, and shows that error events for any fixed number of symbols are asymptotically independent. The fundamental tool behind the analysis is the convex Gaussian min–max theorem.

Design and Security Analysis of Quantum Key Distribution Protocol Over Free-Space Optics Using Dual-Threshold Direct-Detection Receiver

Abstract: This paper proposes a novel design and analyzes security performance of quantum key distribution (QKD) protocol over free-space optics (FSO). Unlike conventional QKD protocols based on physical characteristics of quantum mechanics, the proposed QKD protocol can be implemented on standard FSO systems using subcarrier intensity modulation binary phase shift keying and direct detection with a dual-threshold receiver. Under security constraints, the design criteria for FSO transmitter and receiver, in particular, the modulation depth and the selection of dual-threshold detection, respectively, is analytically investigated. For the security analysis, quantum bit error rate, ergodic secret-key rate, and final key-creation rate are concisely derived in novel closed-form expressions in terms of finite power series, taking into account the channel loss, atmospheric turbulence-induced fading, and receiver noises. Furthermore, Monte-Carlo simulations are performed to verify analytical results and the feasibility of the proposed QKD protocol.

Ambiguity Function Analysis for Dual-Function Radar Communications Using PSK Signaling

Abstract: There is a presumed adverse effect on radar operation brought about from embedding communication signals in radar waveforms. Contrary to that presumption, we show in this paper that modulation of the radar pulse can indeed benefit both radar and communications in the dual system paradigm. This is shown by analyzing the impact of phase-shift keying (PSK) symbol embedding on the ambiguity function (AF) of a multiple-input multiple-output (MIMO) radar. Our analysis shows that the embedded PSK symbols yield reduction in the AF sidelobe peaks for a single pulse as well as for a series of radar pulses. To prove these results, we analyze the AF with and without the PSK symbol embedding. It is shown that the embedding of PSK symbols enable increasing the number of orthogonal transmit waveforms that can be used without increasing the sidelobe levels (SLL) of the corresponding AF.

A ${D}$ -Band Digital Transmitter with 64-QAM and OFDM Free-Space Constellation Formation

Abstract: A ${D}$ -band I/Q RF-DAC featuring two 6-bit DAC elements driven in quadrature, each with its own on-die antenna, and a total effective isotropic radiated power (EIRP) of 13.2 dBm, is demonstrated in a 45-nm SOI-CMOS technology. The carrier signal is first amplified by the 30-dB gain LO path and is directly modulated by the 12 baseband bit streams, without linear upconversion or power amplification. QPSK, 8-PSK, 16-QAM, 32-QAM, and 64-QAM single-carrier (SC) and OFDM constellations are formed in free space and measured above the die at data rates up to 12 Gb/s and at distances over 15 cm. The large-signal bandwidth—from the carrier input pad to the output of the transmitter above the antennas—is 130–142 GHz and was obtained by sweeping the frequency of the ${D}$ -band external carrier, modulating it on die at 0.4 Gb/s using 16-QAM format, and measuring the error vector magnitude (EVM) with an instrumentation receiver. The highest data rate of 12 Gb/s was measured for QPSK SC modulation with a corresponding EVM of −12.2 dB. Lower maximum data rates of 7 Gb/s with −14.3-dB EVM and 3.6 Gb/s with −19-dB EVM were observed for 16-QAM and 64-QAM formats, respectively. Spectral shaping and OFDM transmission were also demonstrated at up to 2.5 Gb/s. The prototype consumes a total of 1.25 W, with an energy efficiency of 104 pJ/b.

Time-Modulated FD-MIMO Array for Integrated Radar and Communication Systems

Abstract: In this letter, we explore time-modulated frequency diverse multiple-input–multiple-output (TMFD-MIMO) array for integrated radar and communications, where the communication information bits are embedded via spread sequence technique during each radar pulse. Orthogonal waveforms are adopted in the TMFD-MIMO array for radar functionality, and a switching time-modulation scheme is applied according to the information bits, i.e., binary phase-shift keying (BPSK) associated spreading sequences. Thus, the number of embedded information bits during each radar pulse equals the number of spread sequences. In doing so, the communication receiver interprets the bits associated with a particular waveform as binary information with prior knowledge of the spread sequences. When compared with existing radar-communications, the achievable data rate is then proportionally increased with the pulse repetition frequency, spreading sequence, and size of the BPSK constellation. Moreover, satisfactory probability of target resolution and signal-to-interference-plus-noise ratio for radar functionality and symbol error rate for communication functionality are achieved.

180-GBaud All-ETDM Single-Carrier Polarization Multiplexed QPSK Transmission over 4480 km

Abstract: We demonstrate PDM-QPSK transmission over 4480 km at a record all-electronically multiplexed symbol rate of 180 GBaud, providing a line rate of 720 Gb/s on a single optical carrier enabled by high-speed InP-DHBT selectors.

UHD Video Transmission Over Bidirectional Underwater Wireless Optical Communication

Abstract: In this paper, we experimentally demonstrate for the first time a bidirectional underwater wireless optical communication system that is capable of transmitting an ultrahigh definition real-time video using a downlink channel while simultaneously receiving the feedback messages on the uplink channel. The links extend up to 4.5 m using QPSK, 16-QAM, and 64-QAM modulations. The system is built using software defined platforms connected to TO-9 packaged pigtailed 520 nm directly modulated green laser diode (LD) with 1.2 GHz bandwidth as the optical transmitter for video streaming on the downlink, and an avalanche photodiode (APD) module as the downlink receiver. The uplink channel is connected to another pigtailed 450 nm directly modulated blue LD with 1.2 GHz bandwidth as the optical uplink transmitter for the feedback channel, and to a second APD as the uplink receiver. We perform laboratory experiments on different water types. The measured throughput is 15 Mb/s for QPSK, and 30 Mb/s for both 16 QAM and 64 QAM. We evaluate the quality of the received live video streams using peak signal-to-noise ratio and achieve values up to 16 dB for 64 QAM when streaming UHD video in harbor II water and 22 dB in clear ocean.

Low-Complexity Belief Propagation Detection for Correlated Large-Scale MIMO Systems

Abstract: In this paper, belief propagation (BP) detection in real domain for large-scale multiple-in multiple-out (MIMO) systems is proposed. The mathematical analysis of message updating rules for independent identically distributed (i.i.d.) and correlated fading MIMO channels are given in detail. The damped BP with damping on the a priori probability vector is employed to improve the performance for the uplink large-scale MIMO systems with correlation among transmitting antennas or loading factor ρ = 1. Based on the convergence analysis, the method of selecting message damping factor δ is presented also. In addition, the adaptive message updating for BP detection is first proposed to provide a good trade-off between performance and complexity. Simulation results have shown that, for 16 × 16 MIMO with quadrature phase shift keying (QPSK) modulation, this approach can show 1 dB performance improvement at BER of 10−2, compared to complex domain single-edge based BP (SE-BP). For 8 × 32 MIMO with correlation among transmitting and receiving antennas, where 16-Quadrature Amplitude Modulation (16-QAM) is employed, simulation results have shown that the proposed adaptive BP detection achieves a complexity reduction of 50% compared to the general BP detection with negligible performance loss. For i.i.d. and correlated fading channels with various antennas configurations, advantages of the proposed approach over existing BP detections as well as MMSE approach have been demonstrated by thorough simulations. Hence, the proposed BP detection is suitable for large-scale MIMO systems, especially for those with high-order modulations. Furthermore, the adaptive BP detection together with message damping is expected to be a good choice for low complexity detection.

300-GHz CMOS QPSK transmitter for 30-Gbps dielectric waveguide communication

Abstract: A 300-GHz 30-Gbps QPSK transmitter is demonstrated in 65-nm CMOS. The transmitter consists of an on-chip multi-mode modulator, an injection locked quadrature oscillator, a 40-GHz bandwidth power amplifier with constant gain and group delay, a 4X frequency multiplier chain to generate a 165-GHz LO signal for a double balanced up-conversion mixer that generates the output at 300 GHz. The transmitter without equalization consumes 180mW with an energy efficiency of 6 pJ/bit.

Burst-mode digital signal processing that pre-calculates FIR filter coefficients for digital coherent pon upstream

Abstract: This paper proposes a burst-mode digital signal processing architecture for digital coherent time-divisionmultiplexed passive optical network (PON) upstream transmission, wherein two key advances are introduced to shorten the preamble length of burst signals required to complete adaptive equalization, as performed by a constant modulus algorithm: tap coefficients of a finite impulse response (FIR) filter are pre-calculated in the optical network unit (ONU) discovery process, and the feed-forward state of polarization compensation is employed before adaptive equalization. The bit error rate performance attained by the proposal is experimentally evaluated; successful burstmode coherent detection with a high sensitivity of -44.7 dBm is demonstrated for 20 Gbit/s single polarizationquadrature phase shift keying burst signals transmitted over a 40 km single mode fiber, even with the use of a short preamble of 1.3 μs, which meets the optical power specifications required for a 512-way split system. The proposal utilizes register request signals whose preamble is longer than those used in current PON systems to optimize the tap coefficients of the FIR filter, which may disrupt smooth ONU registration in high-splitting-ratio systems. To evaluate this impact, numerical calculations based on the Monte Carlo method are conducted, and the results show that the time required to complete the registration of 512 ONUs is just 40 s or so.

An Experimental Channel Capacity Analysis of Cooperative Networks Using Universal Software Radio Peripheral (USRP)

Abstract: Cooperative communication (CC) is one of the best solutions to overcome channel fading and to improve channel capacity. However, most of the researchers evaluate its performance based on mathematical modeling or by simulations. These approaches are often unable to successfully capture many real-world radio signal propagation problems. Hardware based wireless communication test-bed provides reliable and accurate measurements, which are not attainable through other means. This research work investigates experimental performance analysis of CC over direct communication (DC) in the lab environment. The experimental setup is built using Universal Software Radio Peripheral (USRP) and Laboratory Virtual Instrument Engineering Workbench (LabVIEW). A text message is transmitted by using Phase Shift Keying (PSK) modulation schemes. The setup uses amplify and forward (AF) relaying mode and two time slot transmission protocols. The maximum ratio combining (MRC) technique is used for combining SNR at the receiver. Channel capacity analysis is performed in order to evaluate the performance of CC over DC with and without obstacle. Moreover, optimal position of the relay is also analyzed by varying the position of the relay. Extensive experiments are carried out in the lab environment to evaluate the performance of the system for different hardware setups. The results reveal that cooperative communication attains significant improvement in terms of channel capacity of the system.

Evaluation of IEEE802.15.4g for environmental observations

Abstract: IEEE802.15.4g is a low-power wireless standard initially designed for Smart Utility Networks, i.e., for connecting smart meters. IEEE802.15.4g operates at sub-GHz frequencies to offer 2–3× longer communication range compared to its 2.4 GHz counterpart. Although the standard offers 3 PHYs (Frequncy Shift Keying, Orthogonal Frequency Division Multiplexing and Offset-Quadrature Phase Shift Keying) with numerous configurations, 2-FSK at 50 kbps is the mandatory and most prevalent radio setting used. This article looks at whether IEEE802.15.4g can be used to provide connectivity for outdoor deployments. We conduct range measurements using the totality of the standard (all modulations with all further parametrization) in the 863–870 MHz band, within four scenarios which we believe cover most low-power wireless outdoor applications: line of sight, smart agriculture, urban canyon, and smart metering. We show that there are radio settings that outperform the “2-FSK at 50 kbps” base setting in terms of range, throughput and reliability. Results show that highly reliable communications with data rates up to 800 kbps can be achieved in urban environments at 540 m between nodes, and the longest useful radio link is obtained at 779 m. We discuss how IEEE802.15.4g can be used for outdoor operation, and reduce the number of repeater nodes that need to be placed compared to a 2.4 GHz solution.

BER Performance of SEFDM Signals in LTE Fading Channels

Abstract: The BER performance of QPSK spectrally efficient multicarrier signals with non-orthogonal frequency spacing in LTE fading channels is addressed. The receiver structure, based on the reduced size DFT is proposed. This allows to consider the SEFDM signal as an equivalent OFDM signal and to use OFDM pilot symbols for channel estimation. The main advantage of this approach is the possibility of joint equalization and demodulation using sphere decoder or another demodulator. The BER performance of SEFDM in typical LTE fading channels using the proposed reception scheme is comparable with performance of QPSK OFDM with the same number of subcarriers.

All-Optical Transparent Forwarding Relay System for Interstellar Optical Communication Networks

Abstract: An all-optical forwarding relay (AOFR) system is proposed to provide an arbitrary forward with multiple channels and demonstrated by incorporating multiple acquisition, tracking, and pointing (ATP) systems and an arbitrary optical forwarding system (AOFS) with eight channels carrying passive loads. The insertion loss and arbitrary switching time of the AOFS are tested to be $Q$ factor are evaluated with three modulation formats, 997 Mb/s 16-QAM, 27 Gb/s BPSK, and 54 Gb/s QPSK. The results indicate that the connection time of the optical communication is reduced to a few milliseconds by using the rapid arbitrary channel switching and the pre-point of ATP systems. In addition, the AOFR system is fully transparent to the channel wavelengths, forwarding ports, data rates, and modulation formats. To the best of our knowledge, the proposed AOFR system demonstrates the first arbitrary channel forwarding solution for large-capacity passive load among satellites, which will be an enabling solution for future interstellar optical communication networks.

Spread-Spectrum Method Using Multiple Sequences for Underwater Acoustic Communications

Abstract: Direct-sequence spread-spectrum-based approaches have been adopted in underwater acoustic communications. In this paper, multiple sequences utilizing the periodic correlation characteristics of an original spreading waveform are superimposed, modulating multiple distinct symbols simultaneously within each block at the transmitter. Among those superimposed symbols, one is used as the pilot for channel estimation on chip level and others carry data. Similar to existing superposition schemes, the proposed approach also has low receiver complexity, only requiring matched filtering operations. However, the innovation of the proposed approach is perfect interference suppression, cyclic prefix (CP) is inserted to eliminate the interblock interference totally. Combined CP operation leading to an equivalent cyclic channel matrix with circularly shifted versions of spreading sequences, interferences can be solved considerably. The proposed technique is evaluated with both simulation and experimental data analysis. Data processing gives a brief discussion about low probability of detection and low probability of interception.

An Interferer-Tolerant CMOS Code-Domain Receiver Based on N-Path Filters

Abstract: This paper extends N-path filtering to the code domain by proposing code-modulated local oscillator signals. A correlator-based perspective of N-path mixer receiver (RX) is presented to demonstrate interferer-rejection and desired signal reception in a code-domain N-path RX. Pairs of Walsh-function-based codes are proposed for modulating desired RX and known interferers [such as self-interference (SI) from transmitter (TX)] to achieve high interferer rejection. An N-path architecture for concurrent reception of two code-modulated signals is also presented. A 0.3–1.4-GHz 65-nm CMOS implementation achieves 35-dB gain for desired signals and concurrently receives two RX signals while rejecting mismatched spreading codes at RF input. The proposed TX SI mitigation approach results in 38.5-dB rejection for −11.8 dBm 1.46-Mb/s quadrature phase-shift keying (QPSK) modulated SI at the RX input. The RX achieves 23.7-dBm output referred 1dB gain compression (OP1dB) for in-band SI, while consuming ~35 mW and occupies 0.31 mm2. Such code-domain selection/rejection can be used in conjunction with other N-path filtering schemes for signal selection/rejection based on a combination of spatial, spectral, and code-domain properties.

HDM: Hyper-Dimensional Modulation for Robust Low-Power Communications

Abstract: This paper introduces hyper-dimensional modulation (HDM), a new class of practical modulation scheme for robust communication among low-power and low- complexity devices. Unlike conventional orthogonal modulations, HDM conveys numerous information bits per symbol by combining hyper-dimensional vectors that are not strictly orthogonal to each other. Information bits are spread across many elements in the hyper-dimensional vector, thus HDM is tolerant of element-wise failures in high noise channels. Bit error rate (BER) evaluation results confirm that uncoded HDM with 256-dimension outperforms low density parity check (LDPC) and Polar codes with the same block length of 256. Analysis reveals HDM demodulation complexity is lower than that of LDPC and Polar decoders when the block length is relatively small. Moreover, HDM provides graceful tradeoffs between data rate and signal-to-noise ratio for robust short message communications among power- and complexity- constrained devices.

Delta-Sigma Digitization and Optical Coherent Transmission of DOCSIS 3.1 Signals in Hybrid Fiber Coax Networks

Abstract: We first demonstrate delta-sigma digitization and coherent transmission of data over cable system interface specification (DOCSIS) 3.1 signals in a hybrid fiber coax (HFC) network. Twenty 192-MHz DOCSIS 3.1 channels with modulation up to 16384QAM are digitized by a low-pass cascade resonator feedback (CRFB) delta-sigma analog-to-digital converter (ADC) and transmitted over 80-km fiber using coherent single-λ 128-Gb/s dual-polarization (DP) quadrature phase-shift keying (QPSK) and 256-Gb/s DP-16QAM optical links. Both one-bit and two-bit delta-sigma digitization are implemented and supported by the QPSK and 16QAM coherent transmission systems, respectively. To facilitate its practical application in access networks, the coherent system is built using a low-cost narrow-band optical modulator and RF amplifiers. Modulation error ratio (MER) larger than 50 dB is successfully demonstrated for all 20 DOCSIS 3.1 channels, and high-order modulation up to 16384QAM is delivered over fiber for the first time in HFC networks. The raw DOCSIS data capacity is 54 Gb/s with net user information ∼45 Gb/s. Moreover, the bit error ratio (BER) tolerance is evaluated by measuring the MER performance as BER increases. Negligible MER degradation is observed for BER up to 1.5 × 10−6 and 1.7 × 10−4 for one-bit and two-bit digitization, respectively.

Range-Dependent Spatial Modulation Using Frequency Diverse Array for OFDM Wireless Communications

Abstract: An evolution of antenna selection scheme, namely spatial modulation (SM) using phased-array for wireless communications has received much attention, because the spatial index of each phased-array element can be exploited as an additional source for information transmission However, only angle-dependent SM can be achieved for phased-array This means that SM in range-dimension cannot achieve in the SM literature In this paper, we propose both angle- and range-dependent SM using frequency diverse array antenna for orthogonal frequency division multiplexing (OFDM) wireless communications The proposed scheme can operate in twofold: One is that only one array element is chosen for transmission at each instant, and the other one uses multiple array elements to transmit simultaneously, which enhances the spectral efficiency In the receiver, an optimal detector is adopted to jointly estimate the transmitted information symbols and the index of the transmitting elements Specifically, if the array elements simultaneously transmit at slightly distinct carrier frequencies, their coherent summation will give rise to both angle- and range-dependent receiving signal, which provides a possibility to recover the transmitted information Simulation results show that the proposed approach achieves better averaged bit error probability and system capability than phased-array SM schemes for OFDM wireless communications

Experimental 5G New Radio integration with VLC

Abstract: In this paper, integration of 5G New Radio (5G NR) with a Visible Light Communication (VLC) downlink architecture is proposed. This scheme combines two complementary wireless technologies: upcoming 5G NR and VLC to offer indoor enhanced wireless hybrid access able to provide each User Equipment (UE) with very high data rate and positioning support. The data transmission of the 5G NR frame over VLC has been implemented. This represents a novel approach to transmitting 5G NR over VLC by hardware experimentation based on Universal Software Radio Peripheral (USRP). The experiment results show that the proposed scheme with Quadrature Phase Shift Keying (QPSK) mapping achieves a data rate of 14.4 M bits/s and an Error Vector Magnitude (EVM) of 4.78% for a 55 cm free space transmission span.

Experimental Evaluation of OFDM-Based Underwater Visible Light Communication System

Abstract: High-speed, reliable, flexible, and cost-effective underwater wireless communication systems have a wide variety of use in scientific, civilian, and commercial domains. Visible light communication (VLC) seems to be a promising candidate in satisfying majority of the requirements listed above. From this perspective, VLC could easily be deployed in heterogeneous wireless networking scenarios with high quality of service. Therefore, in this paper, an adapted LTE frame structure is implemented for underwater VLC (UVLC) system. The performance of UVLC system employing asymmetrically clipped optical orthogonal frequency division multiplexing modulation technique is practically tested by taking channel estimation and synchronization into account. Also, the effects of varying orthogonal frequency division multiplexing parameters on the system's signal-to-noise ratio and the bit-error-rate (BER) performances are studied. The implementation is tested for quadrature phase shift keying and 16-quadrature amplitude modulation techniques supporting both 128- and 1024-points fast Fourier transform configurations, which correspond to data rates of 1.92 and 15.36 Mbps, respectively. Experimental results show that BER could be reduced down to a level on the order of 10 -6 .

Bounds on Channel Parameter Estimation with 1-Bit Quantization and Oversampling

Abstract: In the design of energy-efficient communication systems with very high bandwidths, the analog-to-digital converter (ADC) plays a crucial role, since its energy consumption grows exponentially with the number of quantization bits. However, high resolution in time domain is less difficult to achieve than high resolution in amplitude domain. This motivates for the design of receivers with L-bit quantization and oversampling w.r.t. Nyquist rate. On the downside, standard receiver synchronization algorithms cannot be applied, since L-bit quantization is a highly non-linear function. To understand the channel parameter estimation performance of such a receiver, the Fisher information (FI) is a helpful measure. Since the closed form evaluation of the FI is not possible for correlated Gaussian noise, we give a lower bound that is an extension of a lower bound by Stein et al. to complex valued channel outputs. If the noise is white, the lower bound is tight. Furthermore, we apply the lower bound for the evaluation of the performance of carrier phase estimation of a QPSK based communication system. We show that for any SNR level oversampling reduces the performance loss due to 1-bit quantization. In the mid and low SNR regime, oversampling reduces the performance loss beyond the loss of 2π encountered in case of 1-bit quantization at Nyquist sampling in the low SNR regime.

Performance Study for SWIPT Cooperative Communication Systems in Shadowed Nakagami Fading Channels

Abstract: In this paper, we investigate the performance of simultaneous wireless information and power transfer cooperative amplify-and-forward communication systems in shadowed Nakagami- $m$ fading channels. Both coherent and non-coherent modulations, namely, binary phase-shift keying (BPSK) and binary differential phase-shift keying (BDPSK) are considered. We propose closed-form expressions of the moment generating function and the probability density function for the received signal-to-noise ratio of the cooperative link. Based on this, we further derive the average bit-error-rate and the outage probability expressions for the systems with both BPSK and BDPSK modulations. All of these expressions are given in closed-form except one in single integral that can be easily evaluated using numerical integration methods. Numerical results are used to confirm the validity of the proposed analytical results. It is shown that the performance of the systems is more susceptible to the fading parameter $m$ than to the shadowing level ${\sigma _{s}}$ and does not change much with the power splitting ratio.