Mm-wave Signal Research Articles

Towards Domain-Independent and Real-Time Gesture Recognition Using Mmwave Signal

Human gesture recognition using millimeter-wave (mmWave) signals provides attractive applications including smart home and in-car interfaces. While existing works achieve promising performance under controlled settings, practical applications are still limited due to the need of intensive data collection, extra training efforts when adapting to new domains, and poor performance for real-time recognition. In this paper, we propose DI-Gesture, a domain-independent and real-time mmWave gesture recognition system. Specifically, we first derive signal variations corresponding to human gestures with spatial-temporal processing. To enhance the robustness of the system and reduce data collecting efforts, we design a data augmentation framework for mmWave signals based on correlations between signal patterns and gesture variations. Furthermore, a spatial-temporal gesture segmentation algorithm is employed for real-time recognition. Extensive experimental results show DI-Gesture achieves an average accuracy of 97.92\%, 99.18\%, and 98.76\% for new users, environments, and locations, respectively. We also evaluate DI-Gesture in challenging scenarios like real-time recognition and sensing at extreme angles, all of which demonstrate the superior robustness and effectiveness of our system.

Achievable Rate Analysis of Millimeter Wave Channels Using Random Coding Error Exponents

With emerging applications, e.g., factory automation, autonomous driving and augmented/virtual reality, there have been increasing technical challenges regarding reliability, latency and data rates for existing communication systems. Owing to abundant available bandwidth, millimeter Wave (mmWave) communications can potentially provide reliable communication with the order of magnitude capacity improvement relative to microwave, e.g., sub 6 GHz communications. Though there are many research results improving throughputs, the latency and reliability performance of mmWave communications is still not quite clear, especially for finite blocklength regimes. In this paper, we investigate achievable rates of mmWave channels by random coding error exponent. Under the assumption of perfect and imperfect channel state information at the receiver (CSIR), exact and approximate analytical expressions of achievable rates are derived to capture the relationship of rate, latency and reliability. Furthermore, we show that the achievable rate always increases as the bandwidth increases with perfect CSIR. However, there exists a critical bandwidth that maximizes the achievable rate for non-line-of-sight mmWave signals with imperfect CSIR, beyond which the achievable rate will decrease with increasing bandwidth. For imperfect CSIR, the training symbol length and power allocation factor for maximizing the achievable rate at the training phase are investigated and closed-form expressions for special cases are derived.

Photonic Filter-Free Scheme for D-Band mm-Wave Signal Generation with Frequency 12-Tupling Only via One Integrated In-Phase and Quadrature Modulator

In this work, we have proposed a new scheme of generating continuously tunable and filter-less D-band millimeter-wave (mm-wave) signal with frequency 12-tupling only via one integrated in-phase and quadrature (I/Q) modulator. The two sub-MZMs in the I/Q modulator, biased at peak point, are applied to eliminate odd order optical tones. By controlling the phase and amplitude of RF driving signals, I/Q modulator bias point, and the optical phase shifter embed in the lower arm of I/Q modulator, a frequency 12-tupling signal can be obtained through the beat frequency in the photodetector. Employing 10 GHz RF drive signal, 120 GHz millimeter wave signal can be realized by detailed mathematical formula derivation and simulation, and optical sideband suppression ratio (OSSR) can reach 37.65 dB and radio frequency sideband suppression ratio (RFSSR) can reach 32.08 dB.

A Review of Millimeter Wave Device-Based Localization and Device-Free Sensing Technologies and Applications

The commercial availability of low-cost millimeterwave (mmWave) communication and radar devices is starting to improve the adoption of such technologies in consumer markets, paving the way for large-scale and dense deployments in fifthgeneration (5G)-and-beyond as well as 6G networks. At the same time, pervasive mmWave access will enable device localization and device-free sensing with unprecedented accuracy, especially with respect to sub-6 GHz commercial-grade devices. This paper surveys the state of the art in device-based localization and device-free sensing using mmWave communication and radar devices, with a focus on indoor deployments. We overview key concepts about mmWave signal propagation and system design, detailing approaches, algorithms and applications for mmWave localization and sensing. Several dimensions are considered, including the main objectives, techniques, and performance of each work, whether they reached an implementation stage, and which hardware platforms or software tools were used. We analyze theoretical (including signal processing and machine learning), technological, and implementation (hardware and prototyping) aspects, exposing under-performing or missing techniques and items towards enabling a highly effective sensing of human parameters, such as position, movement, activity and vital signs. Among many interesting findings, we observe that device-based localization systems would greatly benefit from commercial-grade hardware that exposes channel state information, as well as from a better integration between standardcompliant mmWave initial access and localization algorithms, especially with multiple access points (APs). Moreover, more advanced algorithms requiring zero-initial knowledge of the environment would greatly help improve the adoption of mmWave simultaneous localization and mapping (SLAM). Machine learning (ML)-based algorithms are gaining momentum, but still require the collection of extensive training datasets, and do not yet generalize to any indoor environment, limiting their applicability. Device-free (i.e., radar-based) sensing systems still have to be improved in terms of: improved accuracy in the detection of vital signs (respiration and heart rate) and enhanced robustness/generalization capabilities across different environments; moreover, improved support is needed for the tracking of multiple users, and for the automatic creation of radar networks to enable largescale sensing applications. Finally, integrated systems performing joint communications and sensing are still in their infancy: theoretical and practical advancements are required to add sensing functionalities to mmWave-based channel access protocols based on orthogonal frequency-division multiplexing (OFDM) and multi-antenna technologies.

MmKey: Universal Virtual Keyboard Using A Single Millimeter-Wave Radio

Keyboard acts as one of the most commonly used mediums for human–computer interaction. Today, massive Internet-of-Things (IoT) devices are designed without a physical keyboard as they go tiny, but are almost all equipped with a wireless module for networks. In this work, we aim to enable a universal virtual keyboard using wireless signals, which would allow a typing interface for tiny IoT devices or serve as a portable alternative to the unwieldy physical keyboards. To this end, we present <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mmKey</i> , the first universal virtual keyboard system using a single millimeter-wave (mmWave) radio. By leveraging the unique advantages of mmWave signals, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mmKey</i> converts any flat surface, with a printed paper keyboard, into an effective typing medium. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mmKey</i> enables concurrent keystrokes and supports multiple keyboard layouts (e.g., computer keyboard, piano keyboard, or phone keypad). We design a novel signal processing pipeline to detect, segment and separate, and finally, recognize keystrokes. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mmKey</i> does not need any training except for a minimal one-time effort of only three key-presses for keyboard calibration upon the initial setup. We prototype <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mmKey</i> using a commodity 802.11ad/ay chipset, customized to support radar-like operations, and evaluate it with different keyboard layouts under various settings. Experimental results with ten participants demonstrate a keystroke recognition accuracy of >95% for single-key case and >90% for multikey scenario, which leads to a word recognition accuracy of >97%.

Millimeter Wave Wireless Assisted Robot Navigation With Link State Classification

The millimeter wave (mmWave) bands have attracted considerable attention for high precision localization applications due to the ability to capture high angular and temporal resolution measurements. This paper explores mmWave-based positioning for a target localization problem where a fixed target broadcasts mmWave signals and a mobile robotic agent attempts to capture the signals to locate and navigate to the target. A three-stage procedure is proposed: First, the mobile agent uses tensor decomposition methods to detect the multipath channel components and estimate their parameters. Second, a machine-learning trained classifier is then used to predict the <i>link state</i>, meaning if the strongest path is line-of-sight (LOS) or non-LOS (NLOS). For the NLOS case, the link state predictor also determines if the strongest path arrived via one or more reflections. Third, based on the link state, the agent either follows the estimated angles or uses computer vision or other sensor to explore and map the environment. The method is demonstrated on a large dataset of indoor environments supplemented with ray tracing to simulate the wireless propagation. The path estimation and link state classification are also integrated into a state-of-the-art neural simultaneous localization and mapping (SLAM) module to augment camera and LIDAR-based navigation. It is shown that the link state classifier can successfully generalize to completely new environments outside the training set. In addition, the neural-SLAM module with the wireless path estimation and link state classifier provides rapid navigation to the target, close to a baseline that knows the target location.

Performance Analysis of Random Access Mechanism in 5G Millimeter Wave Networks: Effect of Blockage, Shadowing and Mobility

5G NR has gained importance in academic and industrial research communities in recent times as its millimetre wave (mmWave) band operations offer a promising alternative for next-generation wireless communications. However, the susceptibility of mmWave signals to severe path loss and shadowing requires the use of highly directional antennas. Since the narrow beams are vulnerable to blockages, the interference behaviour becomes the key factor in building the network. In this paper, we propose a blockage model by considering the distribution of buildings in the cell as a Poisson point process. We analytically derive the blockage probability using the queuing theory. Subsequently, we derive the interference statistics using the blockage model considering the spatial randomness of the locations of blockages and User Equipments (UEs). We define and derive the coverage probability of a UE depending on the interference statistics. We calculate the success probability of a preamble transmission of a UE subjected its coverage. The effect of mobility on blockage, coverage and preamble success probability has been presented through extensive simulations.

Novel Multilayer Extreme Learning Machine as a Massive MIMO Receiver for Millimeter Wave Communications

Wireless communication systems working in millimeter-wave (mmWave) frequency bands offer higher bandwidths than traditional radio frequency schemes. This technology allows multibeam steering and data multiplexing with the help of massive multiple-input multiple-output (MIMO) systems. However, supporting large bandwidths at mmWave frequencies is challenging due to the use of large antenna arrays with beamforming, sampling signals with large bandwidths, and baseband signal processing operations at gigabit data rates. Due to the wider bandwidth and higher signal processing requirements of mmWave systems, low-complexity receiver algorithms become important. Previously reported investigations assumed the use of hybrid beamforming structures that reduce power consumption and signal processing tasks. Therefore, the use of artificial neural networks (ANNs) becomes relevant for the processing of mmWave signals as reported in earlier works. In this article, to carry out MIMO combining processing for mmWave communications, we propose a fully complex multilayer extreme learning machine (M-ELM) neural network. We investigate the tuning of the number of neurons in each hidden layer for the proposed method to maximize the system performance and decrease the complexity of the receiver. We compare the results of the introduced M-ELM algorithm with a fully complex extreme learning machine (ELM), fully real ELM, and M-ELM defined in the real plane in terms of spectral efficiency, bit error rate, computational complexity, and processing time. Furthermore, we compare the novel M-ELM strategy with traditional linear MIMO receivers, such as Maximum Ratio and Minimum Mean Square Error, as well as to a multilayer perceptron (MLP) neural network trained offline. The numerical results show that with a good balance between the overall performance and computational cost of the ANN, the fully complex M-ELM MIMO receiver outperforms the other evaluated schemes.

Joint Power Allocation and User Association Optimization for IRS-Assisted mmWave Systems

Intelligent reflecting surface (IRS) is a potential technology to build programmable wireless environment in future communication systems. In this paper, we consider a multi-IRS-assisted multi-base station (multi-BS) multi-user millimeter wave (mmWave) downlink communication system, exploiting IRS to extend mmWave signal coverage to blind spots. Considering the impact of IRS on user association in multi-BS mmWave systems, we formulate a sum rate maximization problem by jointly optimizing passive beamforming at IRS, power allocation and user association. This leads to an intractable non-convex problem, for which to tackle we propose a computationally affordable iterative algorithm, capitalizing on alternating optimization, sequential fractional programming (SFP) and forward-reverse auction (FRA). In particular, passive beamforming at IRS is optimized by utilizing the SFP method, power allocation is solved through means of standard convex optimization method, and user association is handled by the network optimization based FRA algorithm. Simulation results demonstrate that the proposed algorithm can achieve significant performance gains, e.g., it can provide up to 147% higher sum rate compared with the benchmark and 116% higher energy efficiency compared with amplify-and-forward relay.

D-band signal generation and transmission without optical filter based on optical carrier suppression and single-sideband modulation.

We experimentally demonstrated a novel and simple scheme to generate D-band millimeter-wave (mm-wave) signal without optical filter based on optical carrier suppression (OCS) and single-sideband (SSB). One intensity modulator (IM) driven by radio frequency (RF) signal at 50 GHz is firstly employed to generate two tones with channel spacing of 2 x RF frequency based on OCS. Another subsequent in-phase/quadrature (I/Q) modulator driven by RF signal at 30 GHz is then applied to generate SSB signal by using independent sideband (ISB). No optical filter is needed so that the whole system can be simplified. After using a D-band photomixer for detection, we finally generated the vector mm-wave at 130 GHz. Based on the proposed system, 4-Gbaud/8-Gbaud quadrature phase shift keying (QPSK) information carried by the generated D-band mm-wave signals were transmitted over 22.5-km single model fiber (SMF) and 1-m wireless distance radio-over-fiber (ROF) link. Bit-error-ratio (BER) performances under hard/soft-decision forward-error-correction (FEC) threshold are shown respectively in cases of two different signals transmission rates.

A using remodulation filterless scheme of generating frequency 32-tupling millimeter-wave based on two DPMZMs

In this paper, we introduce a filterless system for generating frequency 32-tupling millimeter waves (mm waves) by using two dual-parallel MZMs (DPMZM). A 5 GHz RF signal is used to modulate DPMZM-1. After the first beat, a 20 GHz signal for remodulating DPMZM-2 is generated. Unnecessary sidebands are suppressed by the following methods in the structure of DPMZM-2. Firstly, the ±(4n-2)th-order optical sidebands are suppressed by controlling the phase difference between two Mach-Zehnder modulators (MZMs). Then, the 0th-order sideband is offset by adjusting the value of optical attenuator (OA) and optical phase shifter (OPS). Finally, the 1st and 7th-order optical sidebands nearly disappear by adjusting the modulation index of DPMZM-2 is 3.94. Remaining sidebands enter the photodetector beat frequency to obtain frequency 32-tupling mm waves. Simulation results show that its optical sideband suppression ratio (OSSR) is 27.7 dB and radio frequency sideband suppression ratio (RFSSR) is 27.96 dB, which is consistent with the theory. Using 5 GHz RF signal to drive the DPMZM-1, 160 GHz mm-wave signal was obtained. Furthermore, analyzes the effects of modulation index, optical power and attenuator value on the system performance, optimize the system performance to the best state.

A New and Simple Frequency Quadrupling Millimeter-Wave Signal Generation Enabled by a Single Mach-Zehnder Modulator Without Optical Filter

In this work, we have designed and proposed a new optical method to realize the generating of frequency quadrupling millimeter-wave (mm-wave) only employing one Mach-Zehnder modulator (MZM), and no any optical filter is needed. Compared with the previously reported quadruple frequency scheme, this work greatly simplifies the structure of the system, and makes the performance better and the cost lower. In the scheme, the MZM is operated at peak bias point, which is applied to retain the even order optical sidebands and wipe off the odd order optical harmonics. By tuning-up the optical shifter and optical attenuator (OATT) to control the zeroth order optical carrier returns zero, only ±2nd order optical tones are generated. We demonstrated and discussed the presented scheme feasibility based on the detailed mathematical formula derivation and numerical simulation, the simulation results of which show that employing a sinusoidal radio frequency (RF) source with frequency at 10 GHz to drive a push-pull MZM, a 40 GHz millimeter-wave (mm-wave) signal can be obtained. In the work, the performance of the generated quadrupling signal is that the optical sideband suppression ratio (OSSR) is 34.8 dB and the radio frequency sideband suppression ratio (RFSSR) can reach 27.2 dB.

Enhanced performance of a bidirectional radio over fiber system employing l1-regularization -based sparse second-order volterra non-linear equalizer

A simple bidirectional radio over fiber (RoF) design based on orthogonal frequency division multiplexing (OFDM)-based millimeter wave (mm-wave) signal generation and transmission with compensation of linear and non-linear impairment with the aid of sparse second-order Volterra non-linear equalizer (S2-VNLE) is proposed. At the central station (CS), an optical 60 GHz OFDM-based mm-wave downlink signal is generated by a 16-QAM downlink radio frequency (RF) signal. The generated OFDM-based downlink mm-wave signal is transmitted to the base station (BS) via bidirectional single-mode fiber (SMF) of length 75 km. At BS, the downlink signal is photo detected and transmitted via an antenna to the user end. The 16-QAM uplink RF signal, obtained via a receiving antenna from the user end, is modulated on the unused carrier of the downlink mm-wave signal. The modulated uplink signal is transmitted to the CS through the same bidirectional fiber. The carrier reuse and fiber reuse reduce the system complexity. However, the simultaneous signal co-propagation may induce linear and non-linear impairment, further degrading the system performance and has to be compensated. The compensation of linear and non-linear impairment is done by full Volterra non-linear equalization (FVNLE). However, pruning the insignificant Volterra filter coefficient enables a reduction in computational complexity. The sparse second-order Volterra non-linear equalization (S2-VNLE) is obtained by l1-regularization to cut off the kernels with a moderate contribution. The weights of the tap coefficient are updated by the RLS algorithm. The transmission performance of compensated bidirectional RoF system is investigated. The performance analysis of the bidirectional RoF system shows improved efficiency, having performance closer to FVNLE with reduced system and computational complexity.

Laser requirements for the designof fast laser-driven semiconductor switches for THz and mm-waves.

A reduced parameter model of fast laser-driven semiconductor switches of THz and mm-waves has been developed. The model predicts peak reflectivity and minimum transmissivity of switches, showing good agreement with experimental data, while requiring fewer inputs than published models. This simplification facilitated a systematic survey of laser parameters required for efficient switching. Laser energy density requirements are presented as a function of laser wavelength, laser pulse width, switched frequency, reflection angle, and semiconductor material (silicon or gallium arsenide). Analytical expressions have been derived to explain the dependence of laser requirements on switch parameters and to derive practical minima of required laser energy density. Diffusion is shown to quickly negate the shallow absorption advantage of laser wavelengths shorter than about 500nm in silicon or 800nm in gallium arsenide. Decreasing laser pulse width, to a derived limit, and switching S-polarized THz or mm-wave signals are shown to be means of lowering required laser energy. This is an especially useful result for devices operating at high power levels or THz frequencies, where extended switches are used in quasioptical systems.

84 GHz millimeter-wave PAM4 signal generation based on one PDM-MZM modulator and one polarizer without DAC and filters

In this paper, a novel scheme to employ one external polarization division multiplexing Mach–Zehnder Modulator (PDM-MZM) and one polarizer to generate millimeter-wave four-level pulse amplitude modulation (PAM4) signal is proposed without the usage of expensive and power hungry digital-to-analog converter (DAC). Firstly, we theoretically derive the generation conditions for the mm-wave PAM4 signal scheme. Based on this cost-effective scheme, 6 Gbaud PAM4 signal carried by 84 GHz millimeter-wave transmission over 15 km single-mode fiber (SMF-28) with only 0.5 dB power penalty without any CD compensation is experimentally demonstrated. Furthermore, VPI simulation software is employed to numerically simulate the mm-wave PAM4 signal generation and explore the influences of polarization rotation of the polarizer and direct current (DC)-Bias on the performance of generated W-band signals. In a word, it would be a promising scheme for future 5G short-reach intensity modulation and direct detection (IM/DD) system.

A novel bidirectional RoF link with compensated SBS and RB for 16-QAM OFDM based mm-wave downlink and uplink vector signal generation and transmission on a single fiber

A novel bidirectional RoF link with compensated SBS and RB for 60 GHz OFDM-based 16-QAM downlink and uplink vector signal generation and co-propagation over a single fiber is proposed. At the central station (CS), 60 GHz optical mm-wave is generated and modulated in the optical single-sideband modulation (OSSB) technique by the 16-QAM OFDM downlink vector signal. At the base station (BS), the 60 GHz downlink signal is detected by a high-speed photodetector (PD). The 60 GHz electrical mm-wave signal is transmitted to the user end by an antenna. The uplink carrier is extracted from the unmodulated sideband of the mm-wave downlink vector signal. This reduces the complexity of BS and makes it free from the laser source. The 16-QAM OFDM-based mm-wave uplink signal is received from the user end through an antenna and down-converted to a 10 GHz uplink vector signal. The uplink signal modulates the extracted blank carrier in the OSSB technique. The uplink and downlink vector signals are co-propagated through the standard single bidirectional fiber. Although the carrier reuse over a single fiber reduces the fiber capacity by half, it generates non-linear backscattering such as Rayleigh Backscattering (RB) and Stimulated Brillouin Scattering (SBS). A theoretical analysis is made on the backscattered power and its effect on the fiber transmission. The compensation of SBS by maintaining the SBS threshold and mitigation of RB is carried out by appropriate modulation technique. In addition, downlink and uplink signal with different data rate is transmitted through the compensated bidirectional RoF link, and the transmission performance is analyzed. Based on the analysis, the theoretical model for simultaneous downlink and uplink signal transmission over a single fiber is proposed and verified by the software simulation. The compensated bidirectional RoF link shows up a better performance up to 75 km with negligible power penalty.

A novel advanced 3D‐IPS based on mmWaves and SOM‐MLP neural network

AbstractThis article proposes a new approach for intelligent indoor 3D positioning that works in the millimeter waves (that constitutes a cornerstone of 5G networks). The solution is based on a combination of a multilayer perceptron network and a self‐organizing map. The solution relies on a precise model of the millimeter frequency channel at 60 GHz and the building of a database of fingerprinting of localization data. The solution approach is based on two parts. In the first part, we specified the target environment for positioning as well as the set of millimeter wave (mmWave) access points (APs) to be deployed in predefined positions. Then, we built a reference database of received signal strengths, azimuths of arrival, and elevations of arrival at each 3D position of the target environment (with a predefined step). The second part of the approach consists of designing a novel neural network architecture that is first trained using the database data and then used to estimate any position in the environment based on the information of the received mmWave signals sent by the different mmWave installed APs. In a normal scenario (without loss of data), the obtained results indicate a millimeter level of the generalization error of the estimated 3D positions. In the case of missing data that may due to potential failures in the system, the obtained accuracy is of the order of 34 cm.

Asymmetric dual-SSB modulation for photonic co-frequency mm-wave signals generation and DSP-free receiver.

An asymmetric dual-single-sideband (SSB) modulation scheme for photonic co-frequency millimeter (mm)-wave signals generation and digital signal processing (DSP)-free receiver is experimentally demonstrated for the first time, to the best of our knowledge. To effectively avoid the sideband crosstalk in the traditional symmetric dual-SSB modulation scheme, not only two vector-modulated signals but also two unmodulated sidebands are modulated on the two asymmetric sides of an optical carrier in this scheme. An optical delay line interferometer could easily separate these two asymmetric dual-SSB signals simultaneously in the receiver, and thus the photonic frequency up-conversion is realized. Besides, this scheme is free of dispersion-induced RF power fading thanks to the SSB modulation. By this means, no digital compensation algorithms such as carrier phase recovery, fiber dispersion compensation, and channel equalization are required, contributing to the DSP-free receiver. In our experiment, two 32 GHz 3.2 Gb/s 16-ary quadrature amplitude modulation mm-wave signals are produced using two RF signals with the carrier frequencies of 12 GHz and 20 GHz. The error vector magnitude (EVM) performances of these two mm-wave signals after 25.5 km standard single-mode fiber transmission are better than 3rd Generation Partnership Project requirements without using any digital compensation algorithms.

DSP-free remote antenna unit in a coherent radio over fiber mobile fronthaul for 5G mm-wave mobile communication.

We propose a novel coherent analog radio over fiber (A-RoF) scheme to realize the generation, separation, and detection of four-independent mm-wave signals with the same carrier frequency on a single-wavelength for 5th generation (5G) mobile communication, and no digital signal processing (DSP) algorithms are required in remote antenna unit (RAU). In baseband unit (BBU), four-independent mm-wave signals are modulated on the two orthogonal polarization states of a single wavelength based on a dual-polarization IQ modulator using the dual single-sideband (SSB) modulation and polarization division multiplexing (PDM) technique. In RAU, a novel carrier polarization rotation module based on the self-polarization stabilization technique is proposed, and thus the four-independent mm-wave signals can be detected by self-coherent detection. Besides, the power fading effect induced by the chromatic dispersion could be overcome thanks to the optical SSB modulation, contributing to the increased coverage. By these means, no DSP algorithms are required in RAU, and the latency of signal processing could be significantly reduced. The experimental results show our proposed scheme could support 38.4 Gbps 16-ary quadrature amplitude modulation (16QAM) signals at 14 GHz over 30 km standard single-mode fiber (SSMF) transmission without DSP, satisfying 3rd Generation Partnership Project (3GPP) requirements. Besides, the measured error vector magnitude (EVM) value of 800 MBaud 16QAM signals at 28 GHz over 50 km SSMF transmission is 12.99%. This research provides a potential solution for the 5G mobile fronthaul.

Blockage tolerance in roadside millimeter-wave backhaul networks

With the proliferation of mobile devices with bandwidth-hungry applications, mmWave communication is considered a key enabling technology for 5G and beyond cellular networks. One very promising use of mmWave communication is in wireless backhaul, which has also been investigated by 3GPP as part of an integrated access and backhaul study. Unfortunately, the network performance is hard to predict due to the sensitivity of mmWave signals to blockages, which can result in frequent communication outages. In this paper, we consider wireless backhaul links deployed along the side of a road, which have been widely proposed both in urban environments and on highways. We first investigate the inherent robustness of an interference-free topology for roadside mmWave backhaul. Based on a novel four-type blockage model, we apply stochastic geometry to derive blockage probabilities as a function of the topology parameters and obstacle density, which yields insights that lead to a more robust topology. We then present mechanisms to tolerate any blockages that do occur through reconfiguration. Through extensive simulations, the performance of our proposed algorithms are evaluated for different road scenarios and network topologies. Results show that our algorithms not only achieve high throughputs close to the no-blockage case for mmWave backhaul, but also provide high blockage tolerance rates even in the presence of multiple obstacles along the road.