GHz Radio Link Research Articles

300 GHz Wireless Link Based on Whole Comb Modulation of Integrated Kerr Soliton Combs

300 GHz Wireless Link Based on Whole Comb Modulation of Integrated Kerr Soliton Combs

A 245 GHz Real-Time Wideband Wireless Communication Link with 30 Gbps Data Rate

This paper presents a 245 GHz wireless communications system with a data rate of 30 Giga bits per second (Gbps) at a 1.2 m distance, which proves the potential for future high-speed communications beyond 5G technology. The system consists of low-complexity and real-time base-band modules to provide the high-speed wideband signal processing capability. Multi-channel base-band signals are combined and converted to 15.65 ± 6.25 GHz wideband intermediate frequency (IF) signals. A novel 245 GHz waveguide bandpass filter (BPF) with low loss and high selectivity is designed and applied to a terahertz (THz) front-end for image rejection and noise suppression. Configuration of the base-band, IF, and THz front-end modules is also given in detail. The 245 GHz wireless communication link is demonstrated over a distance of 1.2 m.

Effects of Human Presence and Movement on Received Signal Strength Levels in a 2.4 GHz Wireless Link: An Experimental Study

Effects of Human Presence and Movement on Received Signal Strength Levels in a 2.4 GHz Wireless Link: An Experimental Study

Nonlinear Forwarding Strategy for Firefly Ultra Dense Networks With mmWave Fronthaul Links

We consider the uplink of firefly ultra dense networks which combine the promising features of ultra dense deployment and centralized processing. In these networks, a large number of remote radio units which we denote as firefly nodes (FNs) are spatially distributed over an area. The mobile devices (MDs) in the coverage area are simultaneously connected via sub-6 GHz radio frequency links to all FNs. Unlike the cloud radio access network (C-RAN) architecture, in firefly ultra dense networks, the FNs forward the MDs’ data through multi-hop millimeter-wave (mmWave) links to one or multiple root nodes since the coverage radius of each mmWave link is limited. These root nodes then forward the data via optical fiber links further to a central unit (CU), where the MDs’ signals are decoded. The amount of data that is received at each FN is potentially huge, and hence, efficient signal processing is needed at each FN before the received signals can be forwarded to other FNs. Therefore, we propose a nonlinear processing strategy, which quantizes the received signals at each FN. In particular, we formulate an optimization problem for a local design strategy for the nonlinear forwarding at the FNs, and present an optimal solution by exploiting strong duality and using the Lagrangian method to convert the optimization problem into an unconstrained problem via its dual formulation. A closed-form solution for the primal variables and a bisection algorithm for finding the optimal dual variables are presented. Moreover, based on the cut-set bound, we develop an upper bound on the achievable sum rate of the considered firefly network. The proposed nonlinear forwarding strategy is shown to outperform a benchmark linear forwarding strategy and to approach the performance upper bound in relevant transmit power regimes at the expense of a higher computational complexity. Our results reveal that having more root nodes in the topology improves the performance of linear and nonlinear forwarding but requires additional optical fiber links to the CU.

Empirical Results for Human-Induced Shadowing Events for Indoor 60 GHz Wireless Links

Satisfying the exponential data growth is one of the main challenges for the design of future wireless networks. Given the abundant spectrum availability at millimeter-wave bands, exploiting these frequencies is a natural choice. WiGig (also known as 60 GHz WiFi) allows multi-gigabit transmissions in short range wireless links. The maximum data transfer rates occur in line of sight (LOS) connections. Given the small operating wavelength, obstructing the LOS causes significant power losses, severely impacting the attainable throughput of each user. This article presents empirical results to parameterize typical small-scale fades caused by pedestrians when blocking the LOS, in areas where a WiGig access point serves indoor users. Our results show that fades can be as large as 21 dB, in average. Furthermore, burst of fades are common, lasting up to 5200 ms in 90% of the observed cases.

Various layer techniques to improve video transmission on 20 GHz radio link in a rainy environment

The transmission rate via radio increases to transmitting frequency increment. The higher frequency the higher transmission rate. Video traffics require radio with large bandwidth. This requirement may be fulfilled by the use of millimetre radio transmission on 20 GHz. However, radio signal on millimetre band decreases significantly in presence of rain mainly caused by link attenuation. This paper evaluates the performance of video transmission on 20 GHz in presence of rain on tropical environment. As various layers techniques are available, some techniques such as APA, Java Servlet Alias (JSPA), Digital Subtraction Angiography (DSA) and mac-application layer scheduling are implemented to help radio dealing with rain attenuation. The evaluation results through designed simulations proves that the video quality degrades significantly to rain. The combined technique is able to increase video quality, namely; physical technique up to 0.395 dB, MAC scheduler up to 6.5dB and upper layer technique achieves 1.17 dB.

A Wireless Radio Frequency Triggered Acquisition Device (WRAD) for Self-Synchronised Measurements of the Rate of Change of the MRI Gradient Vector Field for Motion Tracking.

In this paper, we present a device that is capable of wireless synchronization to the MRI pulse sequence time frame with sub-microsecond precision. This is achieved by detecting radio frequency pulses in the parent pulse sequence using a small resonant circuit. The device incorporates a 3-axis pickup coil, constructed using conventional printed circuit board (PCB) manufacturing techniques, to measure the rate of change of the gradient waveforms with respect to time. Using Maxwell's equations, assuming negligible rates of change of curl and divergence, a model of the expected gradient derivative (slew) vector field is presented. A 3-axis Hall effect magnetometer allows for the measurement of the direction of the static magnetic field in the device co-ordinate frame. By combining the magnetometer measurement with the pickup coil voltages and slew vector field model, the orientation and position can be determined to within a precision of 0.1 degrees and 0.1 mm, respectively, using a pulse series lasting 880 μs . The gradient pulses are designed to be sinusoidal, enabling the detection of a phase shift between the time frame of the pickup coil digitization circuit and the gradient amplifiers. The signal processing is performed by a low power micro-controller on the device and the results are transmitted out of the scanner bore using a low latency 2.4 GHz radio link. The device identified an unexpected 40 kHz oscillation relating to the pulse width modulation frequency of the gradient amplifiers that is predominantly in the direction of the static magnetic field. The proposed wireless radio frequency triggered acquisition device enables users to probe the scanner gradient slew vector field with minimal hardware set-up and shows promise for the future developments in the prospective motion correction.

Human activity monitoring system based on wearable sEMG and accelerometer wireless sensor nodes

BackgroundThe human activity monitoring technology is one of the most important technologies for ambient assisted living, surveillance-based security, sport and fitness activities, healthcare of elderly people. The activity monitoring is performed in two steps: the acquisition of body signals and the classification of activities being performed. This paper presents a low-cost wearable wireless system specifically designed to acquire surface electromyography (sEMG) and accelerometer signals for monitoring the human activity when performing sport and fitness activities, as well as in healthcare applications.ResultsThe proposed system consists of several ultralight wireless sensing nodes that are able to acquire, process and efficiently transmit the motion-related (biological and accelerometer) body signals to one or more base stations through a 2.4 GHz radio link using an ad-hoc communication protocol designed on top of the IEEE 802.15.4 physical layer. A user interface software for viewing, recording, and analysing the data was implemented on a control personal computer that is connected through a USB link to the base stations. To demonstrate the capability of the system of detecting the user’s activity, data recorded from a few subjects were used to train and test an automatic classifier for recognizing the type of exercise being performed. The system was tested on four different exercises performed by three people, the automatic classifier achieved an overall accuracy of 85.7% combining the features extracted from acceleration and sEMG signals.ConclusionsA low cost wireless system for the acquisition of sEMG and accelerometer signals has been presented for healthcare and fitness applications. The system consists of wearable sensing nodes that wirelessly transmit the biological and accelerometer signals to one or more base stations. The signals so acquired will be combined and processed in order to detect, monitor and recognize human activities.

360‐degree video offloading using millimeter‐wave communication for cyberphysical system

AbstractThis paper describes an adaptive scheme of 360‐degree video streaming over millimeter‐wave (mmWave) communication for cyberphysical system. It consists of two parts, ie, (1) 360‐degree video streaming and offloading over mmWave 802.11ad 60 GHz wireless link and (2) 360‐degree video decoding, postprocessing, and display by using scalable high‐efficiency video coding. The mmWave communication is high‐speed wireless technology to increase the capacity of video transmission. However, current studies on video streaming over mmWave focus on long distance, and mobile devices process many tasks such as video decoding, postprocessing, and display by themselves. Therefore, the performance of mobile device seriously degrades in the case of high‐resolution video streaming, such as 4K. Furthermore, the synchronization of real‐time video streaming at high speed is an important issue to ensure the quality of service (QoS), especially when the mobile device is moving. Thus, this paper focuses on real‐time video streaming over mmWave with optimized QoS for high‐resolution video. Furthermore, this study implemented an offloading mechanism to handle the offloading tasks between a powerful GPU‐based PC and a mobile device. The experimental results show that the proposed method provides high‐performance 360‐degree video streaming in QoS‐sensitive video streaming applications.

28 GHz Wireless Backhaul Transceiver Characterization and Radio Link Budget

Millimeter wave communication is one of the main disruptive technologies in upcoming 5G mobile networks. One of the first candidate applications, which will be commercially ready by 2020, is wireless backhaul links or wireless last mile communication. This paper provides an analysis of this use-case from radio engineering and implementation perspectives. Furthermore, preliminary experimental results are shown for a proof-of-concept wireless backhaul solution developed within the EU-KR 5GCHAMPION project, which will be showcased during the 2018 Winter Olympic Games in Korea. In this paper, we verify system level calculations and a theoretical link budget analysis with conductive and radiated over-the-air measurements. The results indicate that the implemented radio solution is able to achieve the target key performance indicator, namely, a 2.5 Gbps data rate on average, over a range of up to 200 m.

A High Efficiency and Low Distortion 6 W GaN MMIC Doherty Amplifier for 7 GHz Radio Links

This contribution presents a novel design methodology for Gallium Nitride (GaN) Monolithic Microwave Integrated Circuit (MMIC) Doherty Power Amplifiers (DPAs). The proposed solution allows to mitigate the relevant phase distortion (AM/PM) and gain penalty, typically registered in GaN DPAs, without worsening other key features such as back-off efficiency and amplitude distortion (AM/AM). To this purpose, a non-linear driver stage is introduced in both Carrier and Peaking branches, with the aim to provide a chip-level phase distortion compensation mechanism. The idea is to almost zeroing the overall phase distortion by achieving, in the driver stage, an opposite AM/PM behaviour with respect to the one of the final stage. The theoretical formulation is verified presenting the design and experimental characterization of a GaN MMIC DPA for 7 GHz radio links. The chip has been developed in a commercial $0.25\mu \text {m}$ GaN power process, resulting in a $3\times 3$ mm2 chip area. The realized DPA shows 38 dBm of saturated output power, 16 dB of gain, and less than 3° of phase distortion, with a power added efficiency higher than 41% in 6 dB of output power back off.

A Wide-Field Camera and Fully Remote Operations at the Wyoming Infrared Observatory

Upgrades at the 2.3 meter Wyoming Infrared Observatory telescope have provided the capability for fully remote operations by a single operator from the University of Wyoming campus. A line-of-sight 300 Megabit s−1 11 GHz radio link provides high-speed internet for data transfer and remote operations that include several realtime video feeds. Uninterruptable power is ensured by a 10 kVA battery supply for critical systems and a 55 kW autostart diesel generator capable of running the entire observatory for up to a week. The construction of a new four-element prime-focus corrector with fused-silica elements allows imaging over a 40′ field of view with a new 40962 UV-sensitive prime-focus camera and filter wheel. A new telescope control system facilitates the remote operations model and provides 20″ rms pointing over the usable sky. Taken together, these improvements pave the way for a new generation of sky surveys supporting space-based missions and flexible-cadence observations advancing emerging astrophysical priorities such as planet detection, quasar variability, and long-term time-domain campaigns.

Wireless surface electromyograph and electrocardiograph system on 802.15.4

This paper presents a flexible low-cost wireless system specifically designed to acquire fitness metrics both from surface electromyographic (sEMG) and electrocardiographic (ECG) signals. The system, that can be easily extended to capture and process many other biological signals as well as the motion-related body signals, consists of several ultralight wireless sensing nodes that acquire, amplify, digitize, and transmit the biological or mechanical signals to one or more base stations through a 2.4 GHz radio link using a custom-made communication protocol designed on top of the IEEE 802.15.4 physical layer. The number of wireless nodes the base stations can handle depends on the type of signal being acquired. Each base station is connected through an USB link to a control PC running a user interface software for viewing, recording, and analyzing the data. The system for acquiring signals from wearable nodes in combination with a smartphone application provides a complete platform for monitoring fitness metrics extracted from the signals. 1

NEW IMPLEMENTATION OF MM-WAVE HETERODYNE RECEIVER BASED ON SIX-PORT TECHNOLOGY: CIRCUIT CHARACTERIZATION AND HIGH DATA-RATE DEMODULATION RESULTS

This paper presents a new implementation of a millimeter wave heterodyne receiver based on six-port technology. The six-port circuit is designed using three hybrid couplers H-90 ◦ and a new ring power divider. For the characterization of the circuit, several six-port two-port measurement configurations were designed and fabricated on the same wafer along with calibration standards. The new six-port architecture evaluation based on qi points location demonstrates wideband performances and high coupled-port phase and amplitude balance in the 57-65 GHz frequency band. The six-port model based on S-parameter measurements is then implemented in ADS software, for realistic advanced simulation systems of a short-range 60 GHz wireless link. The millimeter wave frequency conversion is performed using a six-port down-converter. The second frequency conversion uses conventional means due to the low IF frequency value. The demodulation results of a V-band QPSK signal for high data rate from 100 to 1000 MBits/s are presented and discussed. The results of the Bit Error Rate (BER) analysis demonstrate that the proposed architecture can be successfully used for high speed wireless link transmission at 60 GHz.

Secure authentication with energy-harvesting: A multi-dimensional balancing act

The Internet of Things is as much a promise for our future as it is a challenge to our energy provisioning infrastructure. Energy harvesting is an important opportunity to address this challenge, and it may lead to a sustainable Internet of Things with low operation cost and maintenance cost. We study the design space of secure authentication using harvested energy. Secure authentication ensures that one can remotely verify the identity of a Thing, which is a critical step in the absence of a human user-in-the-loop. We assume an operating environment of a wireless node that is authenticated by the host; the wireless node contains an RF frontend, a micro-controller, and energy harvesting unit.The design space of energy-harvested secure authentication is rich and spans the protocol level, the algorithm level, and the (hardware) architecture level. Design decisions at each abstraction level affect the energy efficiency of the resulting solution, and the demands toward the energy-harvesting process. The key objective of this paper is to chart this design space from the energy versus performance point-of-view, and for a standard set of authentication protocols.To validate our analysis, we created a hardware prototype including a solar-based energy harvester, an MSP-430 micro-controller and a 2.4GHz radio link. We have accurately measured the energy consumption of the different components for different authentication algorithms, and at different levels of optimization. Our results show a trade-off over many orders of magnitude in energy and performance. However, the optimization knobs are distributed over every abstraction level. Our contribution therefore provides a comprehensive view at the overall energy optimization problem.

Channel Measurements and Modeling for a 60 GHz Wireless Link Within a Metal Cabinet

This paper presents the channel measurements performed within a closed metal cabinet at 60 GHz covering the frequency range 57–62 GHz. Two different volumes of an empty metal cupboard are considered to emulate the environment of interest (an industrial machine). Furthermore, we have considered a number of scenarios such as line of sight, non line of sight, and placing absorbers. A statistical channel model is provided to aid short-range wireless link design within such a reflective and confined environment. Based on the measurements, the large- and small-scale parameters are extracted and fitted using the standard log-normal and Saleh–Valenzuela models, respectively. The obtained results are characterized by a very small path loss exponent, a single cluster phenomenon, and a significantly large root-mean-square (RMS) delay spread. The results show that covering a wall with absorber material dramatically reduces the RMS delay spread. Finally, the proposed channel model is validated by comparing the measured channel with a simulated channel, where the simulated channel is generated from the extracted parameters.

Multiplexed Millimeter Wave Communication with Dual Orbital Angular Momentum (OAM) Mode Antennas.

Communications using the orbital angular momentum (OAM) of radio waves have attracted much attention in recent years. In this paper, a novel millimeter-wave dual OAM mode antenna is cleverly designed, using which a 60 GHz wireless communication link with two separate OAM channels is experimentally demonstrated. The main body of the dual OAM antenna is a traveling-wave ring resonator using two feeding ports fed by a 90° hybrid coupler. A parabolic reflector is used to focus the beams. All the antenna components are fabricated by 3D printing technique and the electro-less copper plating surface treatment process. The performances of the antenna, such as S-parameters, near-fields, directivity, and isolation between the two OAM modes are measured. Experimental results show that this antenna can radiate two coaxially propagating OAM modes beams simultaneously. The multiplexing and de-multiplexing are easily realized in the antennas themselves. The two OAM mode channels have good isolation of more than 20 dB, thus ensuring the reliable transmission links at the same time.

Resource management in indoor hybrid Fi‐Wi network

AbstractIn‐home networking is becoming a reality. New multimedia applications envisaged for indoor networks require data rate of up to several gigabits per second. In order to meet such a demand for high data rate unlicensed spectrum of 5GHz around 60GHz band is being considered for a potential choice. This pico cellular infrastructure also helps in reducing the interference; at the same time, it is a cause for high deployment cost. Radio‐over‐fiber infrastructure is an obvious choice to feed this last mile high data rate links. The combination of radio‐over‐fiber and 60GHz wireless links, which is known as hybrid Fi‐Wi, is a promising solution to offer high data rate indoor networking. Because of smaller cell size, handoffs between these small cells occur frequently in such a hybrid network. Because of smaller overlapping area between neighbouring cells, guaranteeing quality of service in this network is highly difficult compared with the traditional wireless cellular networks. Thus, resource management in such network is a challenging task. In indoor environments, techniques such as hidden Markov models can be employed to predict movements with high degree of accuracy. In this article, we propose a handoff scheme that utilises movement prediction to reserve bandwidth in only potential target cells before each handoff is initiated. The simulation results show that the proposed scheme performs better than the two other schemes from the literature in terms of the call dropping probability and the call blocking probability. Copyright © 2014 John Wiley & Sons, Ltd.

Design and Development of an Integrated Web-based System for Tropical Rainfall Monitoring

This study is about the design and development of an integrated web-based system for tropical rainfall monitoring. The system gathers data using a network of low-cost, Android-based acoustic rainfall sensors, a nationwide infrastructure of 5GHz wireless broadband links, and remote weather stations. The low-cost Android-based acoustic rainfall sensors are deployed at high densities over a local area and the 5GHz wireless broadband sensors gather rainfall information on a nationwide scale. The sensor network provides information about spatial-variations that are characteristics of tropical rain rates, and complement data from the scarcely deployed remote weather stations. Gathered data is then processed and displayed on a web interface.

Joint Scalable Coding and Routing for 60 GHz Real-Time Live HD Video Streaming Applications

Transmission of high-definition (HD) video is a promising application for 60 GHz wireless links, since very high transmission rates (up to several Gbit/s) are possible. In particular we consider a sports stadium broadcasting system where signals from multiple cameras are transmitted to a central location. Due to the high pathloss of 60 GHz radiation over the large distances encountered in this scenario, the use of relays might be required. The current paper analyzes the joint selection of the routes (relays) and the compression rates from the various sources for maximization of the overall video quality. We consider three different scenarios: (i) each source transmits only to one relay and the relay can receive only one data stream, and (ii) each source can transmit only to a single relay, but relays can aggregate streams from different sources and forward to the destination, and (iii) the source can split its data stream into parallel streams, which can be transmitted via different relays to the destination. For each scenario, we derive the mathematical formulations of the optimization problem and re-formulate them as convex mixed-integer programming, which can guarantee optimal solutions. Extensive simulations demonstrate that high-quality transmission is possible for at least ten cameras over distances of 300 m. Furthermore, optimization of the video quality gives results that can significantly outperform algorithms that maximize data rates.