Low-latency Wireless Communication Research Articles

Diversity Enabled Low-Latency Wireless Communications With Hard Delay Constraints

The emerging next generation Ultra-Reliable and Low-Latency Communications (xURLLC) is expected to play a central role in supporting mission-critical mobile applications because it holds the promise of improving the Quality-of-Service (QoS) substantially. However, it is quite challenging to satisfy the hard delay constraint in harsh wireless environments due to sporadic deep fades, especially when the average power is strictly limited. In this paper, we aim at assuring hard delay constraints with the aid of frequency or spatial diversity techniques. To this end, we focus on both parallel and multiple-input-multiple-output (MIMO) fading channels, in which time domain power adaptation is exploited to provide just-in-time services (JITS). It is shown that the hard delay constraint can be satisfied with a finite average power when the frequency or spatial diversity gains are no less than two. By adopting the implicit function theorem, we reveal the relationship between the required average power, the delay constrained throughput, and the outage probability without power adaptation. Furthermore, by adopting Ferrari’s solution to fourth order algebraic equations, we show that hard delay constrained transmission is feasible even when the sub-channels in the frequency and spatial domains are highly but not fully correlated.

High Throughput and Low Latency Wireless Communication System using Bandwidth-Efficient Transmission for Medical Internet of Thing

High Throughput and Low Latency Wireless Communication System using Bandwidth-Efficient Transmission for Medical Internet of Thing

Blockchain-Based Internet of Things Security and Reliability via SDN-Enabled 5G-VANETs

New opportunities for vehicular Internet of Things (IoT) services using current and modern rational transportation system, along with newer challenges for vehicular ad-hoc networks (VANETs). Along with improved network performance, a workable and trustworthy security system is required to handle trust management while maintaining user privacy. A key technology for extremely dependable, low-latency wireless communication services is the newly developed 5G mobile communication system. Additionally, the software-defined network (SDN) design allows for network control and worldwide data collection within the 5G-VANET. As a result, real-time IoT services for monitoring and reporting on transportation can be effectively supported. Both open the door for a cutting-edge automobile security system.This paper investigates the security and privacy issue in the transportation system and the vehicular IoT environment in SDN-enabled 5G-VANET. A blockchain-based security framework is created to support the vehicular IoT services, such as real-time cloud-based video reporting and trust management on vehicular messaging, due to the decentralised and immutable nature of blockchain. The 5G-VANET model with SDN support and the framework's scheduling processes are specifically illustrated in this study. The outcomes of the numerical simulation also demonstrate that it is possible to detect malicious vehicular nodes or communications while maintaining acceptable overhead and network performance impacts in large-scale scenarios. We show how our design considerably ensures a secure and reliable vehicle IoT environment with user privacy preserved through case studies and theoretical analysis.

Converging Telco-Grade Solutions 5G and beyond to Support Production in Industry 4.0

The Industry 4.0 initiative has been showing the way for industrial production to optimize operations based on collecting, processing, and sharing data. There are new requirements on the production floor: flexible but ultra-reliable, low latency wireless communications through interoperable systems can share data. Further challenges of data sharing and storage arise when diverse systems come into play at the Manufacturing Operations Management and Business Planning & Logistics levels. The emerging complex cyber-physical systems of systems need to be engineered with care. Regarding industrial requirements, the telecommunication industry has many similarities to production—including ultra-reliability, high complexity, and having humans “in-the-loop”. The current paper aims to provide an overview of converging telco-grade solutions that can be successfully applied in the wide sense of industrial production. These toolsets range from model-driven engineering through system interoperability frameworks, 5G- and 6G-supported manufacturing, and the telco-cloud to speech recognition in noisy environments.

Ultra-Reliable and Low-Latency Wireless Communications in the High SNR Regime: A Cross-Layer Tradeoff

Ultra-Reliable and Low-Latency Communications (URLLC) has attracted considerable attention because of its potential applications in factory automation, automated driving, and telesurgery anticipated for the era of the sixth-Generation (6G) networks. In URLLC with random channel gains and a hard delay constraint, the scheduling of backlogged queues and finite blocklength coding in the physical layer will make it very challenging to specify its performance limits. In this paper, we focus our attention on the asymptotic cross-layer analysis of URLLC when the Signal-to-Noise Ratio (SNR) is sufficiently high. More specifically, we find that a fundamental tradeoff exists among the service capability, latency, and error probability in the high SNR regime, which is characterized by a gain conservation equation. The main result of this work reveals that the sum of our defined service rate gain, real-time gain, and reliability gain is equal to one under the optimal policy. Numerical simulations are also exploited to validate that the derived gain conservation equation holds even with bounded random arrival.

Metric-Combining Multiuser Detection Using Replica Cancellation with RTS and Enhanced CTS for High-Reliable and Low-Latency Wireless Communications

Metric-Combining Multiuser Detection Using Replica Cancellation with RTS and Enhanced CTS for High-Reliable and Low-Latency Wireless Communications

A Deterministic Scheduling Policy for Low-Latency Wireless Communication With Continuous Channel States

Low-latency and energy-efficient wireless communication holds the potential of enabling the industrial internet of things (IIoT), automatic driving, and telesurgery. Cross-layer scheduling, which is aware of both the channel and queue states, has attracted considerable attention recently because it is capable of reducing the average delay substantially while meeting a given average power constraint. As a result, there has been considerable work, in which joint channel and buffer aware scheduling is formulated as a constrained Markov decision process (CMDP). In general, the optimal solution to a CMDP problem is characterized by the stationary probability of actions, yielding probabilistic cross-layer scheduling with possibly high complexity in practice. In this paper, we are interested in the low-latency and energy-efficient stationary cross-layer scheduling policy for wireless channels with continuous channel states, e.g. Rayleigh fading. It is interestingly shown that a deterministic cross-layer scheduling policy can achieve the optimal tradeoff between the average delay and power. In other words, the signaling complexity of cross-layer scheduling can be significantly reduced without causing sub-optimality. Simulation results also demonstrate that our work provides a low-complexity solution for low-latency and energy-efficient wireless communications.

Haplets: Finger-Worn Wireless and Low-Encumbrance Vibrotactile Haptic Feedback for Virtual and Augmented Reality

We introduce Haplets, a wearable, low-encumbrance, finger-worn, wireless haptic device that provides vibrotactile feedback for hand tracking applications in virtual and augmented reality. Haplets are small enough to fit on the back of the fingers and fingernails while leaving the fingertips free for interacting with real-world objects. Through robust physically-simulated hands and low-latency wireless communication, Haplets can render haptic feedback in the form of impacts and textures, and supplements the experience with pseudo-haptic illusions. When used in conjunction with handheld tools, such as a pen, Haplets provide haptic feedback for otherwise passive tools in virtual reality, such as for emulating friction and pressure-sensitivity. We present the design and engineering for the hardware for Haplets, as well as the software framework for haptic rendering. As an example use case, we present a user study in which Haplets are used to improve the line width accuracy of a pressure-sensitive pen in a virtual reality drawing task. We also demonstrate Haplets used during manipulation of objects and during a painting and sculpting scenario in virtual reality. Haplets, at the very least, can be used as a prototyping platform for haptic feedback in virtual reality.

Joint Lossy Compression and Power Allocation in Low Latency Wireless Communications for IIoT: A Cross-Layer Approach

Low-latency communication is expected to play a key role in the Industrial Internet of Things (IIoT). Although there has been considerable effort on reducing latency, few attention has been focused on the low-latency transmission of distortion-tolerant data, e.g. IIoT's analog samples, over fading channels. In this paper, we present a cross-layer approach to jointly adapt the transmission power, rate, and compression ratio based on the instantaneous buffer and channel states. In particular, to minimize the average delay under both average power and distortion constraints, we formulate a Constrained Markov Decision Process (CMDP) with multi-dimensional state and action spaces. A novel solution is then presented by judiciously decomposing the multi-dimensional CMDP into a deterministic hierarchical optimization consisting of a linear programming and a convex optimization problem. Furthermore, we show the optimality of a threshold-based scheduling policy that highly reduces the complexity and present an optimal delay-power-distortion tradeoff that characterizes a fundamental performance tradeoff between the physical, network, and application layers. The joint lossy compression and power allocation scheme realizes a deep cross-layer optimization of source coding, queuing control, and wireless transmission, which outperforms the traditional cross-layer design consisting of only two layers, not to mention layered protocols.

Federated-Learning-Based Client Scheduling for Low-Latency Wireless Communications

Motivated by the ever-increasing demands for massive data processing and intelligent data analysis at the network edge, federated learning (FL), a distributed architecture for machine learning, has been introduced to enhance edge intelligence without compromising data privacy. Nonetheless, due to the large number of edge devices (referred to as clients in FL) with only limited wireless resources, client scheduling, which chooses only a subset of devices to participate in each round of FL, becomes a more feasible option. Unfortunately, the training latency can be intolerable in the iterative process of FL. To tackle the challenge, this article introduces update-importance-based client scheduling schemes to reduce the required number of rounds. Then latency-based client scheduling schemes are proposed to shorten the time interval for each round. We consider the scenario where no prior information regarding the channel state and the resource usage of the devices is available, and propose a scheme based on the multi-armed bandit theory to strike a balance between exploration and exploitation. Finally, we propose a latency-based technique that exploits update importance to reduce the training time. Computer simulation results are presented to evaluate the convergence rate with respect to the rounds and wall-clock time consumption.

On the Cooperative Relaying Strategies for Multi-Core Wireless Network-on-Chip

Recently, hybrid wired-wireless Network-on-Chip (WiNoC) has been proposed as a suitable communication fabric to provide scalability and satisfy high performance demands of the exascale era of modern multi/many-core System-on-Chip (SoC) design. A well accepted low-latency wireless communication fabric for WiNoCs is millimeter wave (mm-Wave). However, the wireless channel of mm-Wave is lossy due to free space signal radiation with both dielectric propagation loss (DPL) and molecular absorption attenuation (MAA). This is exacerbated for edge situated cores and in macro-chips embodying thousands of cores. To this end, this article proposes efficient relaying techniques to improve the signal strength of the wireless channel in the WiNoCs using on-chip networking approaches under the realistic SoC channel conditions. First, we propose a realistic relay communication channel for the WiNoCs to characterise both MAA and DPL which have drastic effect on the performance. We then derive and show that the channel capacity for a single-relay WiNoC employing Amplify-and-Forward (AF) and Decode-and-Forward (DF) relaying protocols increases by up to 20% and 25%, respectively, compared to the conventional direct transmission. The AF protocol outperforms the DF mode for shorter transmissions between the relay and the destination cores, while the reverse is observed in other conditions. A hybrid protocol is then proposed to exploit the performance advantages of both relaying protocols to address the unbalanced distance between the cores, providing the maximal channel capacity close to the cutset bound. Finally, our approach is further validated in multi-relay WiNoCs where the communications of the remote cores is assisted by multiple intermediate cores along with the details of associated realistic channel model in emerging many-core SoCs.

5G beamforming techniques for the coverage of intended directions in modern wireless communication: in-depth review

AbstractThe growing need of the compact and portable antennas with high speed and low latency wireless communication is the present and future demand of the voice over Internet protocol, on-demand bandwidth, and multimedia applications. Fifth-generation (5G) covers certain low-frequency bands under 6 GHz spectrum, and most of the high-frequency bands under 60 GHz. 5G is the part of the millimeter wave spectrum (30–300 GHz) and is introduced to overcome the problem of spectrum shortage due to exponential enhancement of wireless applications in industry, medical, airborne, radar, satellite, and research fields. The International Telecommunication Union's objective of wireless communications promises to provide higher data rates up to 10 Gbps for 5G mobile users and connectivity to the artificial intelligence devices, along with high spectral efficiencies and enhanced coverage. The users for the 5G require around 5 and 50 Gbps of data rates for low and high mobility, respectively. Beamforming in 5G is the modern powerful technique for the coverage of the intended user/direction using the narrow beam width radiation patterns. A brief survey on 5G beamforming techniques, i.e. analog, digital, hybrid, switched, and adaptive etc. and its types, working algorithms, design of compact antennas, gain, and size/type of the substrates is carried out in this paper. The study of the hybrid coupler, branchline coupler, Wilkinson power divider, and Butler matrix in beamforming is required for 5G smart antennas. Different beam widths like ±15, ±35, ±45, and ±55° etc. are produced for the intended directions using a variety of beamforming techniques. From lower to higher frequency band beamforming applications with Roger's Duroid 4003/4350/5880, tectonic, and aluminum oxide dielectric substrates are discussed here. Various beamforming techniques with their merits, demerits, and applications are included in the paper for the knowledge extension of the beamforming antenna designers and research community.

BTMPP: Balancing Trust Management and Privacy Preservation for Emergency Message Dissemination in Vehicular Networks

As a potential application field of the sixth-generation (6G) communication technology and a promising part of massive Internet of Things (IoT), vehicular networks have attracted considerable attention from both academia and industry in recent years, where the cooperative safety applications are a significant branch. It is widely acknowledged that 6G is able to provide high-throughput and low-latency wireless communication capability for vehicular networks, support massive interconnectivity in vehicular networks with diverse service requirements, and significantly improve the performance of vehicular networks. Both trust management and privacy preservation play significant roles in vehicular networks, and there exists a tradeoff between them. For providing a satisfactory solution to balance the trust management and privacy preservation in vehicular networks, we put forward a novel scheme named as BTMPP (which is able to provide both the precise trust management and strong conditional privacy preservation simultaneously) in this article by leveraging the famous bloom filter (BF)-based private set intersection (PSI) technology. Furthermore, the theoretical analysis for the correctness, strong conditional privacy preservation capability, strong robustness, precise trust management, and the other features is detailed, and a series of simulations are conducted. The results reveal that the proposed scheme significantly outperforms the existing schemes in several aspects.

Performance Evaluation of Polar Coded Filtered OFDM for Low Latency Wireless Communications

The fifth generation new radio (5G-NR) system design is aimed to have ultra-large transmission rate, massive capacity, massive device connectivity, enhanced mobile broadband (eMBB) services, and ultra-reliable low communication latency (URLLC) services. To support the various challenges and specifications, new wireless communication technologies including new notorious waveforms, forward error correction codes (FEC), non-orthogonal waveforms as well as massive multiple input multiple output (MIMO) antenna schemes have been introduced to aid the progress of pliable 5G air interface system design. Cyclic prefix based orthogonal frequency division multiplexing (CP-OFDM) has been broadly selected in 4G-OFDM based long term evaluation(LTE), Wi-Fi, and other mobile communications due to the benefit of high spectral efficiency, ease of development and easy to integrate with MIMO systems, etc. However, the conventional CP-OFDM technology has some drawbacks, such as high out of band (OOB) emission leakage, an exact requirement of synchronization, and a limited number of CP lengths. Filtered OFDM (FOFDM) is a flexible foundational waveform by applying subband filtering on existing CP-OFDM which can support the needs of the waveform for 5G air interface. In this paper, a spectrally efficient waveform called polar coded filtered OFDM (PC-FOFDM) is proposed to fulfil these requirements for high data rate ultra-reliable low latency communications. This paper investigates bit error rate (BER) performance of PC-FOFDM scheme over additive white Gaussian noise (AWGN) channel and compares the results with PC-OFDM. The simulation results show that the PC-FOFDM scheme outperforms PC-OFDM in terms of spectrum efficiency, BER performance, and error vector magnitude (EVM).

Vision-Based Personal Safety Messages (PSMs) Generation for Connected Vehicles

Vehicle-to-pedestrian (V2P) communication can significantly improve pedestrian safety in a connected vehicle environment. However, pedestrian safety is hindered as pedestrians often do not carry hand-held devices that provide low latency wireless communication (e.g., dedicated short-range communication (DSRC)-enabled device or emerging 5G-enabled cell phone) to communicate with nearby connected vehicles. The contribution of this paper lies in developing a vision-based approach to generate personal safety messages (PSMs) in real-time utilizing video streams from roadside traffic cameras, following the standard of the Society of Automotive Engineers (SAE) (SAE J2945) that can be used by connected vehicle pedestrian safety applications. Our analysis reveals that the vision-based approach can estimate pedestrians' location and speed more accurately than existing DSRC-enabled pedestrian hand-held devices. A system-level validation was performed by developing a connected vehicle related pedestrian safety application, “pedestrian in signalized crosswalk warning (PSCW),” that uses the generated PSMs from our vision-based approach. The results from the calculated average time-to-collision (TTC) value demonstrate the efficacy of our method in generating real-time collision warnings to avoid possible vehicle-pedestrian collisions. Our analysis also shows that the vision-based pedestrian safety warning system satisfies the latency requirement for the PSCW safety application in a connected vehicle environment.

5G Based Machine Remote Operation Development Utilizing Digital Twin

Abstract Remote operations of mobile machinery require reliable and flexible wireless communication. 5G networks will provide ultra-reliable and low latency wireless communications upon whichremote operations, real-time control and data acquisition can be implemented. In this paper we present a demonstration system and first experiments for remote mobile machinery control system utilizing 5G radio and a digital twin with a hardware-in-the-loop development system. Our experimental results indicate that with a suitable edge computing architecture an order of magnitude improvement in delay and jitter over exiting LTE infrastructure can be expected from future 5G networks.

Performance Analysis of Blockchain Systems With Wireless Mobile Miners

In this letter, a novel framework that uses wireless mobile miners (MMs) for computation purposes in a blockchain system is proposed. To operate blockchains over such a wireless mobile network with minimum forking events, it is imperative to maintain low-latency wireless communications between MMs and communication nodes (CNs) that store the blockchain ledgers. To analyze the sensitivity of the system to latency, the probability of occurrence of a forking event is theoretically derived. Also, in mobile blockchain using MMs, minimizing energy consumption required for networking and computation is essential to extend the operation time of MMs. Hence, the average energy consumption of an MM is derived as a function of the system parameters such as the number of MMs and power consumed by the computing, transmission, and mobility processes of the MMs. Simulation results verify the analytical derivations and show that using a larger number of MMs can reduce the energy consumption by up to 95% compared to a blockchain system with a single MM.

High-Reliability and Low-Latency Wireless Communication for Internet of Things: Challenges, Fundamentals, and Enabling Technologies

As one of the key enabling technologies of emerging smart societies and industries (i.e., industry 4.0), the Internet of Things (IoT) has evolved significantly in both technologies and applications. It is estimated that more than 25 billion devices will be connected by wireless IoT networks by 2020. In addition to ubiquitous connectivity, many envisioned applications of IoT, such as industrial automation, vehicle-to-everything (V2X) networks, smart grids, and remote surgery, will have stringent transmission latency and reliability requirements, which may not be supported by existing systems. Thus, there is an urgent need for rethinking the entire communication protocol stack for wireless IoT networks. In this tutorial paper, we review the various application scenarios, fundamental performance limits, and potential technical solutions for high-reliability and low-latency (HRLL) wireless IoT networks. We discuss physical, MAC (medium access control), and network layers of wireless IoT networks, which all have significant impacts on latency and reliability. For the physical layer, we discuss the fundamental information-theoretic limits for HRLL communications, and then we also introduce a frame structure and preamble design for HRLL communications. Then practical channel codes with finite block length are reviewed. For the MAC layer, we first discuss optimized spectrum and power resource management schemes and then recently proposed grant-free schemes are discussed. For the network layer, we discuss the optimized network structure (traffic dispersion and network densification), the optimal traffic allocation schemes and network coding schemes to minimize latency.

Statistical delay bounds for automatic repeat request protocols with pipelining

The recent trend towards low-latency wireless communication requires a notion of non-ergodic capacity that deals with delays. Significant research has contributed such results for relevant physical layer aspects. Less attention has been paid to actual implementations of link layer automatic repeat request protocols. Instead, error-free transmission using instantaneous channel state information, simple stop-and-wait protocols, or instantaneous feedback are frequently assumed. In this work, we investigate protocols with pipelining that deal with packet errors under non-negligible round-trip-times. We define a stochastic service curve model of a general class of automatic repeat request protocols with pipelining and derive statistical waiting time and sojourn time bounds. We discover two regimes: under low to moderate load retransmissions cause the largest part of the sojourn time, whereas under high load the waiting time dominates the sojourn time. Generally, with increasing round-trip-time the basic cases of stop-and-wait protocols or instantaneous feedback neglect relevant effects and provide less accurate estimates.

Energy-Efficient and Low-Latency Massive SIMO Using Noncoherent ML Detection for Industrial IoT Communications

To enable ultrareliable low-latency wireless communications required in the Industrial Internet of Things, in this paper we develop an energy-based modulation [i.e., non-negative pulse amplitude modulation (PAM)] constellation design framework for noncoherent detection in massive single-input multiple-output (SIMO) systems. We consider that one single-antenna transmitter communicates to a receiver with a large number of antennas over a Rayleigh fading channel, and the receiver decodes the transmitted information at the end of every symbol. For such an SIMO system with non-negative PAM modulation, we first propose a fast noncoherent maximum-likelihood decoding algorithm and derive a closed-form expression of its symbol error probability (SEP). We then enhance the system energy efficiency by finding the optimal PAM constellation that minimizes the exact SEP subject to a total signal power constraint for such a system with an arbitrary number of receiver antennas, signal-to-noise ratio (SNR), and constellation size. Furthermore, the closed-form upper and lower bounds on the optimal SEP are derived. Based on these bounds, the exact expression for coding gain of the dominant term of the SEP is presented for such an optimal massive SIMO system. We also present an asymptotic SEP expression at a high SNR regime and the approximate diversity gain of the system. Simulation results for the proposed optimal PAM constellation validate the theoretical analysis, and show that our presented optimal constellation attains significant performance gains over the currently available minimum-distance-based constellation systems.