Remote Unit Research Articles

Design and Analysis of a Novel Concept-Based Unmanned Aerial Vehicle with Ground Traversing Capability

Abstract Unmanned aerial vehicle (UAV) is a typical aircraft that is operated remotely by a human operator or autonomously by an on-board microcontroller. The UAV typically carries offensive ordnance, target designators, sensors or electronic transmitters designed for one or more applications. Such application can be in the field of defence surveillance, border patrol, search, bomb disposals, logistics and so forth. These UAVs are also being used in some other areas, such as medical purposes including for medicine delivery, rescue operations, agricultural applications and so on. However, these UAVs can only fly in the sky, and they cannot travel on the ground for other applications. Therefore, in this paper, we design and present the novel concept-based UAV, which can also travel on the ground and rough terrain as an unmanned ground vehicle (UGV). This means that according to our requirement, we can use this as a quadcopter and caterpillar wheel–based UGV using a single remote control unit. Further, the current study also briefly discusses the two-dimensional (2D) and three-dimensional (3D) SolidWorks models of the novel concept-based combined vehicle (UAV + UGV), together with a physical model of a combined vehicle (UAV + UGV) and its various components. Moreover, the kinematic analysis of a combined vehicle (UAV + UGV) has been studied, and the motion controlling kinematic equations have been derived. Then, the real-time aerial and ground motions and orientations and control-based experimental results of a combined vehicle (UAV + UGV) are presented to demonstrate the robustness and effectiveness of the proposed vehicle.

Home Automation Using Multinode Cooperative Network

Home monitoring can be implemented in a low-cost manner using this proposed project. The existing system involves high-cost equipment which cannot be utilized by a normal person. In the proposed model the overall design of home monitoring uses the multinode co-operative network. It mainly focuses on the development of the home monitoring system which can be implemented using NodeMCU. The highlight of the project is to use the NodeMCU embedded with Wi-Fi technology which enables the transmission of the sensed data to the cloud. The Proposed model will monitor the working status of various equipment in the home. Based on the data sensed from the equipment the information is shared in a cooperative manner with the remote monitoring unit. The Amplify and Forward cooperative protocol is used to transmit the data to the destination. The main advantage of the cooperative network is to enhance the signal reception quality and to improve the monitoring of the status round the clock. A popular open-source platform to execute the process of transmission, processing, and receiving data without losing the intensity. We are going to use multiple nodes to decrease the fault while working with them. These node MCUs are used for many projects as it is very cheap. It also has integrated support for the Wi-Fi network. Its compact size is an added advantage. It has low energy consumption property and reliable secure cloud storage. They have a user-friendly programming environment and a scripting language that is easy to learn. These are mainly used in IoT home automation, security alarms, incubators, controller, Internet smoke alarms, serial port monitors, and VR trackers.

Power-Over-Fiber Using Double-Clad Fibers

Power-over-fiber (PWoF) is an attractive technology for transmitting power utilizing optical fibers. Because optical fibers are nonconductive power lines, and can transmit data signals simultaneously, PWoF enables us to provide usages that are not feasible with conventional electric power supply systems using copper wires. This study presents an overview of PWoF using various types of optical fibers, and introduces a practical application for powering remote antenna units (RAUs) in mobile communications. To power a RAU, the author’s group has worked on PWoF using double-clad fibers, which comprise a single-mode core and an inner cladding that surrounds the core. The core structure is more suitable for simultaneous high-speed data signals and high-power feed light transmission than other optical fibers. To demonstrate the feasibility, the experimental demonstrations of the authors’ group are introduced in detail. In addition, the latest performance comparison of PWoF reported so far is presented, and future prospects are described.

System design and laboratory tests of an autonomous seismic station for space applications

We introduce a reference concept for a small and lightweight instrument carrier system for operation in isolated areas on Earth (or even on other celestial bodies) that autonomously records data after deployment at a site remote from the main station, thus called Remote Unit (RU). In particular, we present here concepts for realizing an autonomously operating seismometer, including support functions provided by encapsulating the actual instrument into the RU carrier. The conceptualization of the RU is based on the design of MASCOT, and intended for evolving into an instrument carrier for lunar exploration. Still in this paper we focus on the functionality needed for realizing the remote and autonomous aspects of the concept. Evolutionary steps needed for the system design to survive on a planetary body are briefly discussed, but not intensively covered in this paper, but elsewhere.We developed two prototypes of this RU including three seismic sensors each, either fixed, the other one with a built-in self-leveling mechanism. We used standard seismic sensors, which were integrated into a lightweight instrument carrier equipped with all required support structures for remote terrestrial operation, including power, thermal control, and data acquisition (total mass of prototypes not exceeding 3 ​kg and 10 ​kg, respectively). We have carried out laboratory tests and evaluated seismic data from these two types of RU to evaluate noise levels, spectral response, and overall performance of the systems. We demonstrate that the systems provide reproducible data at high signal levels, which warrant comfortable scientific interpretation of seismic data from active and passive experiments. Noise level and detected spectral anomalies (due to mechanical structure and associated Eigenfrequencies) are well within expectations.

Security in Supervisory Control and Data Acquisition (SCADA) based Industrial Control Systems: Challenges and Solutions

Industrial control systems (ICS) play a vital role in monitoring and controlling the plants like power grids, oil and gas industries, manufacturing industries, and nuclear power plants. Present research and development in information and communication technologies have changed the domains of industrial control systems from traditional electromagnetic to network- based digital systems. This domain shift has created better interfaces for communication between physical processes and the control units. Eventually, making the complex process of monitoring and controlling the industries easier, with the help of internet connections and computing technologies. The field instruments such as sensors and actuators and the physical processes in industries are controlled and monitored by programmable logic controllers (PLC), remote telemetric units (RTU), and supervisory control and data acquisition systems (SCADA) with the help of communication protocols. The seamless integration of the information technologies (IT) and operational technologies (OT) make the management of the industrial environment foster. However, the inclusion of new technologies that increase the number of internet connections, the new communication protocols, and interfaces that run on open-source software, brings up new threats and challenges in addition to existing vulnerabilities in these classical legacy-based heterogeneous hardware and software systems. Due to the increase in the number of security incidents on critical infrastructures, the security considerations for SCADA systems/ICS are gaining interest among researchers. In this paper, we provide a description of SCADA/ICS components, architecture, and communication protocols. Additionally, we discuss details of existing vulnerabilities in hardware, software, and communication protocols. Further, we highlight some prominent security incidents and their motives behind them. We analyse the existing state of OT and IT security in SCADA systems by classifying the SCADA components among them. Finally, we provide security recommendations based on current trends and also discuss open research problems in SCADA security.

Guest Editorial: Enhanced Fronthaul for 5G and Beyond

In the radio access network (RAN) infrastructure, fronthaul links territorially disperse remote units (RUs) to distributed units (DUs) in regular or open RAN. With the fifth generation (5G) rollout worldwide and the active research on technologies beyond 5G, fronthaul has become a critical part of RAN to balance throughput, delay, reliability, and security. Based on a group of Tier 1 operators' insights on 5G deployment, a recent technology analysis report expects the 5G fronthaul transmission market to reach more than US$2 billion in revenue by 2024, almost triple the current rollout.

Wireless Fronthaul for 5G and Future Radio Access Networks: Challenges and Enabling Technologies

Wireless networks have been evolving at a frenetic pace to meet the ever increasing demands for higher capacity, lower latency, and massive number of connections. In the fifth generation (5G) radio access networks (RANS), millimeter-wave and higher band radio are instrumental in achieving such stringent requirements. The network deployment must go through significant densification to meet the extremely high demand of data traffic. This imposes a big challenge to the network architecture as well as to the design of fronthaul transport links in the network. Fronthaul is generally referred to as the connection link between baseband units and remote radio units. Fiber-based connections have been conventionally the mainstream technology for fronthaul. However, fiber-based fronthaul may not scale in a cost-effective way to meet dense and flexible deployment requirements. Wireless fronthaul could be a viable solution and an attractive alternative to fiber for such deployments. In this article, we first provide an overview of emerging fronthaul interfaces and requirements. We then highlight the enabling technologies and solutions that can be applied in wireless fronthaul to meet future fronthaul capacity and latency requirements in a robust manner. The discussed technologies include performing fronthaul compression, leveraging new higher band spectrum, optimizing high rank line-of-sight multiple-input multiple-output (LoS-MIMO) and applying forward-looking technologies like reconfigurable intelligent surfaces. Wireless fronthaul has the advantages of flexibility, scalability, and low cost compared to fiber-based fronthaul. However, it also raises challenges in reliably delivering the required key performance indicators. Simulation results of wireless fronthaul for a wide range of distances and point-to-multipoint deployment scenarios show that robust and reliable performance can be achieved using high rank LoS-MIMO at high millimeter-wave bands. The analysis of this article indicates that wireless fronthaul can be designed to meet the requirements and be an attractive option for future disaggregated RAN deployments.

Beam Tracking for Distributed Millimeter-Wave Massive MIMO Systems Based on the Unscented Kalman Filter

In this letter, a beam tracking problem is studied in distributed millimeter-wave (mm-wave) massive multiple-input multiple-output (MIMO) systems. Firstly, a monopulse beam direction estimation method for a distributed mm-wave massive MIMO system is introduced. However, this method is very sensitive to noise and must be performed in every time slot in a single-user moving scene. To improve its accuracy, a monopulse beam tracking method based on the unscented Kalman filter (UKF) for a distributed mm-wave massive MIMO system is proposed. The simulation results show that the proposed beam tracking method has better tracking performance under different SNRs and different numbers of antennas of remote antenna units (RAUs), and its robustness and generalizability are quite well.

Photonic-enabled radio-frequency self-interference cancellation incorporated into an in-band full-duplex radio-over-fiber system

A photonic approach for radio-frequency (RF) self-interference cancellation (SIC) incorporated in an in-band full-duplex radio-over-fiber system is proposed. A dual-polarization binary phase-shift keying modulator is used for dual-polarization multiplexing at the central office (CO). A local oscillator signal and an intermediate-frequency signal carrying the downlink data are single-sideband modulated on the two polarization directions of the modulator, respectively. The optical signal is then transmitted to the remote unit, where the optical signals in the two polarization directions are split into two parts. One part is detected to generate the up-converted downlink RF signal, and the other part is re-modulated by the uplink RF signal and the self-interference, which is then transmitted back to the CO for the signal down-conversion and SIC via the optical domain signal adjustment and balanced detection. The functions of SIC, frequency up-conversion, down-conversion, and fiber transmission with dispersion immunity are all incorporated in the system. An experiment is performed. Cancellation depths of more than 39 dB for the single-tone signal and more than 20 dB for the 20-MBaud 16 quadrature amplitude modulation signal are achieved in the back-to-back case. The performance of the system does not have a significant decline when a section of 4.1-km optical fiber is incorporated.

High-performance dual-band radio-over-fiber link for future 5G radio access applications

For the fronthaul between the baseband unit and the remote radio unit (RRU), radio over fiber (RoF) is promising to replace the Common Public Radio Interface in beyond fifth-generation and the sixth-generation wireless communication systems. The weight, size, and power consumption of the RRU can be greatly reduced, along with easy support for the millimeter-wave band. In this paper, a dual-band RoF link is proposed, where flexible switching between high-frequency (28 GHz) and low-frequency (3.5 GHz) RF channels is realized through polarization control. Single-sideband modulation is performed on 28 GHz signals to avoid periodic power fading during long-distance fiber transmission. By adjusting the DC bias, the third-order intermodulation distortion component in the 3.5 GHz signal is suppressed, and the spur-free dynamic range (SFDR) is improved. Experimental results show a channel isolation of above 43 dB. The link gain of the 28 GHz signal channel is flat, and the SFDR of the 3.5 GHz signal channel can reach 118.6 d B ⋅ H z 4 / 5 . In the case of RF vector signal transmission, the adjacent channel power ratio of the 3.5 GHz signal channel is optimally up to 48 dB, and the error vector magnitude is 2.9%.

Weed Plucking Robot with Wireless Technologies

Abstract: The main function of this robot is to remove the unwanted tiny plants or grass from the main crop, this system is very useful for farmer which avoids lot of manual work. Plucking weeds manually is very painful activity and also consumes lot of time and therefore this mechanism is designed. Since it is a prototype module, basic version of grass or tiny weeds plucking mechanism is designed with spur gears. The moving mechanism is constructed with motorized wheels, for this purpose 30RPM motors are used. The mechanism is designed to move in all directions including reverse direction. The plucking mechanism designed with spur gears is attached with another motor shaft. Two spur gears are used and are meshed with each other, when the vehicle is moving and when the gears are rolling, the grass or tiny weeds will be removed by the gear mechanism. The demo module is constructed with small spur gears, with this the basic concept can be proved and it is not a full fledged mechanism. With the help of a remote control unit constructed with 12E, 12D chips & RF transmitter, entire machine can be controlled. H Bridge IC is used to drive the wheel drive motors through remote and weed picking mechanism must be activated manually through third DC motor. Moving mechanism is controlled through 2 DC motors and is controlled independently by which mechanism will be moved in all directions. 12V, 1Ah Rechargeable battery is used to run the entire system and this battery can be charged through ac adapter. The remote is constructed using four keys to move the robot forward, reverse, right and left directions. By pressing any control key in the remote unit, the encoder chip generates proportionate digital code, which is fed to the RF transmitter for transmitting the data. In the receiver, the received data will be decoded by the 12D IC and based on this code this chip enables the H Bridge IC by which the corresponding motor rotates in one direction. Likewise both DC motors will be controlled independently according to the command code received by the communication system.

Passive beamformer based remote beamforming scheme for radio-over-fiber systems: Experimental demonstration using 28-GHz band reflectarray

This paper proposes and experimentally demonstrates a passive beamformer based remote beamforming scheme for millimeter-wave band radio-over-fiber systems. The proposed scheme can control the beam direction of remote radio units (RRUs) from the central station (CS); it yields extremely simple RRUs for flexible and cost-effective deployment. The proposed scheme sets a passive beamformer such as beamforming network, reflector, or lens in the RRU and different wavelengths are assigned to each input port of the passive beamformer. This configuration offers remote beam switching by just carrier wavelength switching at CS. Multi-beam operation can be also realized simply by using multiple wavelengths simultaneously. Experiments on a 28 GHz band reflectarray are conducted. The feasibility of remote beam switching by wavelength switching is confirmed. 5G signal transmission over 20 km of single-mode fiber and 6.3 m air link is successfully achieved with error vector magnitude values of 2.71–3.55%, which satisfies the 3GPP requirements of 8%.

A Hierarchical Modulation Enabled SNR Allocable Delta-Sigma Digital Mobile Fronthaul System

Internet of everything is being build up rapidly, which causes much higher requirements towards the flexibility of communication resources, especially the adaptivity of the fronthaul to various transmission distances and capacities. In this paper, we proposed a low-cost and spectrum efficient 5G fronthaul broadband connection solution that combines hierarchical modulation technology and delta-sigma modulation. The proposed scheme can double the number of accesses without occupying extra wavelengths. Moreover, such architecture can flexibly allocate the SNR of a group of remote radio units for different user requirement of transmission rate and reaches. Simulation results show that the proposed scheme can increase the access distance of the fronthaul network by 23% and the capacity by 16.7%. The feasibility of the solution is verified through a proof-of-concept experiment. After 20 km transmission, the OFDM-64QAM and -256QAM signal with a center frequency of 3.5 GHz and a bandwidth of 500 MHz can meet the EVM requirements of 8% and 3.5%, respectively. And when the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${R_{LM}}$</tex-math></inline-formula> of the hierarchical PAM4 signal is 0.6, the ROP required by the most-significant bit branch can be reduced by ∼1.5 dB.

Performance of Remote Radio Unit Selection in Millimeter-Wave Distributed Antenna Systems Over Fluctuating Two-Ray Fading

Millimeter wave (mmWave) is a promising future wireless communication technology. To overcome the high path loss in mmWave band, distributed antenna systems (DASs) with each base station (BS) connecting to multiple remote radio units (RRUs) is a candidate solution. To better characterize the small-scale fading of mmWave channels, the fluctuating two-ray (FTR) was recently proposed. In this letter, we study the performance of RRU selection in mmWave DASs over the FTR fading. First, simplified closed-form expressions are, respectively, provided for the probability density function (PDF) and cumulative distribution function (CDF) of signal-to-noise ratio (SNR). Then, we derive the exact closed-form expressions and their high-SNR approximations for the outage probability and ergodic rate, respectively. The effect of RRU number and FTR-fading parameters on the performance are further revealed from these high-SNR approximations. Simulations validate our analytical results.

Adopting MQTT for a multi protocols IoMT system

&lt;span&gt;Coronavirus disease (COVID-19) altered the way of caregiving and the new pandemic forced the health systems to adopt new treatment protocols in which remote follow-up is essential. This paper introduces a proposed system to link a remote healthcare unit as it is inside the hospital. Two different network protocols; a global system for mobile communication (GSM) and Wi-Fi were used to simulate the heath data transfer from the two different geographical locations, using Raspberry Pi development board and Microcontroller units. Message queuing telemetry transport (MQTT) protocol was employed to transfer the measured data from the healthcare unit to the hospital’s Gateway. The gateway is used to route the aggregated health data from healthcare units to the hospital server, doctors’ dashboards, and the further processing. The system was successfully implemented and tested, where the experimental tests show that the remote healthcare units using a GSM network consumed about 900 mWh. A high percentage of success data packets transfer was recorded within the network framework as it reaches 99.89% with an average round trip time (RTT) of 7.5 milliseconds and a data transfer rate up to 12.3 kbps.&lt;/span&gt;

Implementation of a Full Optically-Powered 5G NR Fiber-Wireless System

We report the implementation of a full optically-powered 5G new radio (5G NR) fiber-wireless (FiWi) system based on power-over-fiber (PoF) and radio-over-fiber (RoF) technologies. Our approach enables the simultaneous transmission of a 5G NR signal at 3.5 GHz with bandwidth up to 100 MHz and a 2.2-W optical power signal employing dedicated fiber-optics links. The optical-wireless data link consists of a 12.5-km single-mode fiber (SMF) optical fronthaul followed by a 10-m wireless propagation environment, which is the longest wireless reach reported in literature up to now, regarding optically-powered FiWi systems. The proposed PoF system is able to deliver stable electrical power up to 475 mW, by means of using a 100-m multimode fiber (MMF) link, with the purpose of optically powering a 5G NR remote antenna unit (RAU). An overall power transmission efficiency (PTE) of 23.5% is experimentally demonstrated in a real 5G NR system. Furthermore, the FiWi system performance is investigated in accordance with the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$3^{\mathrm rd}$</tex-math></inline-formula> generation partnership project (3GPP) Release 15 requirements, in terms of root mean square error vector magnitude ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\mathrm EVM}_{\mathrm RMS}$</tex-math></inline-formula> ). The proposed optically-powered 5G NR FiWi system provides 500 Mbit/s throughput with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\mathrm EVM}_{\mathrm RMS}$</tex-math></inline-formula> as low as 3.9%, employing 64-quadrature amplitude modulation (QAM) without using optical amplification.

An MPSK Millimeter-Wave Point-to-Point Link With Radio Over Fiber Synchronous Baseband Receiver

This paper demonstrates a millimeter-wave point-to-point radio link of MPSK (QPSK, 8-PSK, and 16-PSK) modulation without using any analog to digital converter (ADC). The proposed point-to-point radio link, not only use the radio over fiber (RoF) concept to extend the transmit distance of the central unit and the remote radio unit, but also use the clock and data recovery (CDR) applied in the optical-electrical converter (OEC) to recover the MPSK intermediate frequency (IF) signals frequency offset. Compared with the traditional RoF link, the proposed point-to-point synchronous radio link eliminated the high-speed ADC requirement for the digital-intermediate-frequency-over-fiber (DIFoF) link, which can significantly reduce the complexity and the cost of the remote radio unit. Simultaneously, we have designed a simple symbol synchronization algorithm to realize the real-time point-to-point radio link on an Field Programmable Gate Array (FPGA). The proposed millimeter-wave radio link has successfully demonstrated 6 Gbps QPSK transmission and can tolerate a frequency offset up to 100 MHz.

Simultaneous RF Self-Interference Cancellation, Local Oscillator Generation, Frequency up- and down-Conversion in an Integrated In-Band Full-Duplex 5G RF Transceiver Front-End

Wideband radio-frequency (RF) self-interference cancellation (SIC), local oscillator (LO) generation, frequency up-, and down-conversion are all crucial for an in-band full-duplex (IBFD) 5G RF transceiver front-end. In this paper, a microwave photonic approach enabled by only one optical dual-polarization IQ modulator (DP-IQMZM) is proposed to simultaneously realize wideband RF SIC, LO generation, frequency up- and down-conversion. Note that, the LO signal with high spectral purity and low phase noise is produced by a dual-loop optoelectronic oscillator (OEO) using a self-polarization stabilization structure, and the generated LO signal is applied for frequency up- and down-conversion. Besides, the optical single-sideband signal is produced at the output of this 5G RF transceiver for uplink transmission from the remote antenna unit (RAU) to the baseband unit (BBU), so the power fading induced by fiber dispersion could be completely suppressed. A proof-of-concept experiment is performed, and the LO signal with the central frequency of 10&#x00A0;GHz, the phase noise performance of &#x2212;108.97&#x00A0;dBc&#x002F;Hz at a frequency offset of 10&#x00A0;kHz is achieved. A 5 &#x00D7; 20&#x00A0;MHz Long Term Evolution (LTE) 16&#x002F;64-ary quadrature amplitude modulation-orthogonal frequency division multiplexing (16&#x002F;64QAM-OFDM) signal with the central frequency of 12.6&#x00A0;GHz is down-converted to 2.6&#x00A0;GHz. Meanwhile, the cancellation ratio of 30.22&#x00A0;dB and 26.26&#x00A0;dB could be achieved when the bandwidth of the self-interference signal is 150&#x00A0;MHz and 300&#x00A0;MHz, respectively. Moreover, a 3 &#x00D7; 20&#x00A0;MHz LTE 64QAM-OFDM signal with a central frequency of 2.6&#x00A0;GHz is up-converted to 12.6&#x00A0;GHz, and the electrical signal-to-noise ratio of the generated RF signal can achieve 31.34&#x00A0;dB. The measured error vector magnitude performance shows that the generated down- and up-converted signal both meet the 3^rd Generation Partnership Project (3GPP) requirements for 5G systems.

Pre-filtered and post-filtered 1-bit delta sigma modulator for fronthaul downlinks

The fifth generation (5G) mobile fronthaul transmission system is being investigated, and one potential solution is to use 1-bit bandpass delta–sigma modulation, thus a bandpass filter (BPF) can be used to convert a digital 1-bit signal back to original analog RF signal at remote radio units. It is inevitable that this bandpass filter can induce phase and amplitude distortion to the signal, which may severely distort the signal integrity. In this work, two novel delta sigma modulators (DSM), called pre-filtered and post-filtered DSM, are proposed to compensate for the above both phase and amplitude distortion. The two designs are verified by using both simulation and experimentation with radio-over-fiber (RoF) links up to 20 km. The 5G signal used in the simulation and experimentation is a 200 MHz 64-QAM orthogonal frequency-division multiplexing signal centered at 2.5 GHz. An error vector magnitude is improved by up to ∼19 dB using the above two DSMs.

Toward integrating bidirectional multiband data and power transmission using double clad optical fibers for the next generation disaster resilient managing communication systems

AbstractDuring the cyclones and floods, all through the nation, the telecommunication network services were the most hit, leaving numerous individuals stripped from the ability to contact their precious ones. This paper is to demonstrate potential communications during such power blackouts. The double clad fiber is used for optically powering, transmitting and receiving the data to and from the remote antenna units by the Bidirectional method. The RoF multiband signals such as baseband, millimeter wave, and microwave, are transmitted and received bidirectionally by the single mode core, and power in outer clad to the Remote Antenna Unit. By the proposed RoF link transmission of 1 Gbps over a 100‐Km DCF with an optical power of about12.0 W is achieved.