Radio Frequency Transceiver Research Articles

Low complexity energy efficient orthogonal frequency division multiplexing communication system over underwater acoustic channel by partial transmit sequence peak to average power ratio reduction

We discourse the power consumption for underwater acoustic transceivers in this study. We have proposed a less computational complex underwater acoustic OFDM communication system. Underwater acoustic transceivers consume more power than that Radio frequency transceivers. The methods which are being utilized in Radio frequency cannot directly be applied to underwater acoustic system. Therefore, it needs to re-investigated and the new techniques should be introduced to achieve reliable and energy efficient acoustic data transmission. It also relies upon condition of acoustic channel and transmission distances. There is long-term battery-operated deployment of underwater acoustic modems in some applications. To maintain sustainable network operations an energy efficient OFDM system is required. In this paper, we have used partial transmit sequence peak to average power ratio reduction technique to design a novel energy efficient OFDM system for underwater acoustic channel with less complexity. This framework will be remarkably helpful in future for long term battery deployed applications of underwater acoustic transceivers. The results are expected to provide the enhanced performance of PAPR reduction with better sustainability. It has less complexity and better energy efficiency for underwater acoustic sensor/sensing networks.

Implementing Zigbee-based Wireless Sensor Network in the Design of Water Quality Monitoring System

This study presents the design and development of a precision fishing technology utilized in water quality monitoring with phytoremediation system using a Zigbee-based Wireless Sensor Network. The system afforded a real-time water quality monitoring using multiple sensors spatially deployed. The sensor node implemented in the Wireless Sensor Network to perform data sensing utilities with the water quality parameters including the water temperature, pH level, water dissolved oxygen and the water level during high-tide and low-tide. During the development, a P89V51RD2 microcontroller, ZigBee module with IEEE 802.15.4 standard, and radio frequency (RF) transceiver were utilized. The developed precision fishing technology utilized the Internet of Things architecture. The IoT device layer includes the temperature sensor, pH sensor, dissolved oxygen sensor, and the water level sensor. Phytoremediation was also used as an alternative solution for soil and water remediation. Further studies using recent and advanced remote sensing technologies and IoT-based solutions can be developed to address issues in the primary sector of the economy.

Elemental: An Open-Source Wireless Hardware and Software Platform for Building Energy and Indoor Environmental Monitoring and Control.

This work demonstrates an open-source hardware and software platform for monitoring the performance of buildings, called Elemental, that is designed to provide data on indoor environmental quality, energy usage, HVAC operation, and other factors to its users. It combines: (i) custom printed circuit boards (PCBs) with RFM69 frequency shift keying (FSK) radio frequency (RF) transceivers for wireless sensors, control nodes, and USB gateway, (ii) a Raspberry Pi 3B with custom firmware acting as either a centralized or distributed backhaul, and (iii) a custom dockerized application for the backend called Brood that serves as the director software managing message brokering via Message Queuing Telemetry Transport (MQTT) protocol using VerneMQ, database storage using InfluxDB, and data visualization using Grafana. The platform is built around the idea of a private, secure, and open technology for the built environment. Among its many applications, the platform allows occupants to investigate anomalies in energy usage, environmental quality, and thermal performance via a comprehensive dashboard with rich querying capabilities. It also includes multiple frontends to view and analyze building activity data, which can be used directly in building controls or to provide recommendations on how to increase operational efficiency or improve operating conditions. Here, we demonstrate three distinct applications of the Elemental platform, including: (1) deployment in a research lab for long-term data collection and automated analysis, (2) use as a full-home energy and environmental monitoring solution, and (3) fault and anomaly detection and diagnostics of individual building systems at the zone-level. Through these applications we demonstrate that the platform allows easy and virtually unlimited datalogging, monitoring, and analysis of real-time sensor data with low setup costs. Low-power sensor nodes placed in abundance in a building can also provide precise and immediate fault-detection, allowing for tuning equipment for more efficient operation and faster maintenance during the lifetime of the building.

High-Accuracy Narrowband Software-Defined Radar Using Successive Multiple-Frequency Continuous-Wave Modulation for Sensing Applications

This paper describes a software-defined radar sensor based on successive multiple-frequency continuous-wave (S-MFCW) modulation. S-MFCW is a radar modulation technique capable of detecting static and moving targets with high accuracy while modulating the transmitted signal over a narrow frequency bandwidth. The proposed software-defined radar is implemented as a highly reconfigurable system made of a field-programmable gate array (FPGA)-based system-on-chip (SoC), a wideband homodyne radio frequency (RF) transceiver, and two antennas. The utilized programmable general-purpose SoC and transceiver front end allow for some of the radar components to be reconfigured by a software program running on the SoC. This radar system adequately follows the software-defined radar paradigm wherein most of the radar operation is configured and controlled using software programs, thus providing the ability to combine multiple radar functions on the same hardware resource. The presented radar sensor is experimentally evaluated in both outdoor and indoor measurement scenarios. The radar operates in the S-band and occupies a narrow virtual bandwidth of 34 MHz when transmitting S-MFCW tones whose frequencies are shifted by two gaps of 4 and 30 MHz, from 3.550 to 3.584 GHz. Experimental results show that the proposed radar system is capable of measuring short-range targets with a range accuracy of less than 21 cm.

Low-cost web-based Supervisory Control and Data Acquisition system for a microgrid testbed: A case study in design and implementation for academic and research applications

This paper presents the design and implementation of a low-cost Supervisory Control and Data Acquisition system based on a Web interface to be applied to a Hybrid Renewable Energy System (HRES) microgrid. This development will provide a reliable and low-cost control and data acquisition systems for the Renewable Energy Laboratory at Universitat Politècnica de València (LabDER-UPV) in Spain, oriented to the research on microgrid stability and energy generation. The developed low-cost SCADA operates on a microgrid that incorporates a photovoltaic array, a wind turbine, a biomass gasification plant and a battery bank as an energy storage system. Sensors and power meters for electrical parameters, such as voltage, current, frequency, power factor, power generation, and energy consumption, were processed digitally and integrated into Arduino-based devices. A master device on a Raspberry-PI board was set up to send all this information to a local database (DB), and a MySQL Web-DB linked to a Web SCADA interface, programmed in HTML5. The communications protocols include TCP/IP, I2C, SPI, and Serial communication; Arduino-based slave devices communicate with the master Raspberry-PI using NRF24L01 wireless radio frequency transceivers. Finally, a comparison between a standard SCADA against the developed Web-based SCADA system is carried out. The results of the operative tests and the cost comparison of the own-designed developed Web-SCADA system prove its reliability and low-cost, on average an 86% cheaper than a standard brandmark solution, for controlling, monitoring and data logging information, as well as for local and remote operation system when applied to the HRES microgrid testbed.

A design of a 5.6 GHz frequency synthesizer with switched bias LIT VCO and low noise on‐chip LDO regulator for 5G applications

A design of a 5.6 GHz frequency synthesizer with switched bias LIT VCO and low noise on‐chip LDO regulator for 5G applications

Energy-Efficient Wireless Communications: From Energy Modeling to Performance Evaluation

In this paper, we analyze energy-efficient communications based on an advanced energy consumption model for wireless devices. The developed model captures relationships between transmission power, transceiver distance, modulation order, channel fading, power amplifier (PA) effects, as well as other circuit components in the radio frequency transceiver. Based the developed model, we are able to identify the optimal modulation order in terms of energy-efficiency under different situations (e.g., different transceiver distance, different PA classes and efficiencies, different pulse shape, etc). This provides an important framework for analyzing energy-efficient communications for different wireless systems ranging from cellular networks to wireless Internet of Things.

Implementation and Performance Analysis of a Non-codebook Based MU-MIMO System with Dynamic Precoding for TDD LTE-Advanced

This paper presents a non-codebook based Multiple User Multiple Input Multiple Output (MU-MIMO) test-bed system for Time Division Duplex (TDD) Long Term Evolution-Advanced (LTE-A). The system was implemented for verifying the performance of a dynamic precoding procedure that selects the most appropriate precoder among a given set of precoding techniques. Using two parameters, the propagation path gain and the condition number of the channel matrix, the proposed MU-MIMO system can adaptively switch the precoding software to guarantee that the upper bound Bit Error Rate (BER) is maintained with a minimum computational burden. This paper also presents a novel procedure for accurately and simply calibrating the multiple Radio Frequency (RF) paths of the multiple antennas and RF transceivers of the MU-MIMO system. From various experimental measurements obtained from the implemented test-bed system, the upper bound BER, which was arbitrarily set to 10−3 in this paper, can be maintained with the simplest precoder, Zero Forcing (ZF), unless the propagation path gain becomes less than 0.25. It was also found in the experimental tests that, as the distance between 2 handsets becomes shorter than 1 meter, which causes the condition number of the channel matrix to be larger than 17, the precoder should be switched from Lattice Reduction (LR) to Tomlinson-Harashima Precoding (THP) when the minimum distance between base-station and each handset maintained is set to at least 6 meters.

An Ultrasonically Powered Wireless System for In Vivo Gastric Slow-Wave Recording.

This paper summarizes our recent progress towards Gastric Seed which is an ultrasonically interrogated millimeter-sized implant for gastric electrical activity (also known as slow waves, SWs) recording. We present a proof-of-concept wireless system designed to collect, transmit, and store in vivo SW signals by integrating a prototype Gastric Seed chip, fabricated in a 0.35-μm 2P4M CMOS process, with a commercial-off-the-shelf (COTS) amplifier, 10-bit analog-to-digital converter (ADC), and pair of microcontrollers (MCU) as radio-frequency (RF) transceivers. The chip includes ultrasonic self-regulated power management and addressable pulse-based data transfer. Utilizing two pairs of millimeter-sized stacked power/data ultrasonic transducers spaced by 6 cm in a water tank, the chip achieved a regulated voltage of 2.5 V and a data rate of 16 kbps. The amplifier was configured to have a gain of 60 dB with a 3-dB bandwidth of 18 mHz to 500 mHz. The MCU's built-in 10-bit ADC and RF transceiver were used to digitize the SW signal and transmit the data to a computer. In vivo, SW was recorded wirelessly from the stomach of an anesthetized rat. The recorded SWs showed a frequency of 1.5 cycle-per-minute (cpm) and maximum and minimum amplitudes of 1.03 mV and 0.28 mV peak-to-peak, respectively.

A Simple MCU and RF-Based Wetness Detector

Diapers rash are harmful to the babies and the elderly; so, wetness detection technologies have been sophisticated by many research worker to assist in discovering these events. The study and survey offered here looked into a radio frequency-based microcontroller and GSM for wetness detection. One of the crucial concerns is not only the detection of humidity but the Health complications of diapers rash. This study utilizes a wetness detection system with different types of alarms: audio buzz, flashing light emitting diode, and Smartphone. Our proposed system consists of a wetness sensor, microcontroller, radio frequency transceiver microcontroller, and GSM modem, or computer. Two thin wires between diaper sheets or layers of medical dressing set up the wetness sensor. The two or four thin wires connect to a couple of pressing studs sticking out from one end of the diaper or gauze. When the wires are wetted, the resistance between the studs falls down a pre-established threshold, launching the alarm. Radio Frequency transceiver passes the warning alarm through Microcontroller to the GSM modem. Consequently, Smartphone and other devices forward the alarm to whom it may concern wetness or bleeding is occurring.

Coherent dual‐band radar system based on a unique antenna and a photonics‐based transceiver

This study reports the development of a coherent dual-band radar system consisting of a frequency selective surface (FSS)-based dual-band focal-point/Cassegrain parabolic antenna and a single photonics-based transceiver. The proposed antenna enables to simultaneously operate in the S and X bands due to the use of an FSS-based sub-reflector. Numerical and experimental results of the antenna reflection coefficient, radiation pattern and gain have been shown in excellent agreement for both frequency bands. Furthermore, the proposed dual-band antenna has been applied in conjunction with a photonics-based coherent dual-band radio-frequency transceiver operating in the same bands. The authors’ innovative radar system has been properly validated by the detection and ranging of a commercial aircraft and a helicopter on a building roof, using S and X bands concurrently.

Doppler Shift Time Expansion Resolution and Spectral Performance in Wideband Real-Time RF Channel Emulators

The possibility to test a radio frequency transceiver through the use of appropriate channel emulators allows evaluating their performance under various operating conditions. Many systems are able to operate with a relatively limited instantaneous bandwidth by applying known statistical models. Sometimes, it is necessary to evaluate the performance of a RF transceiver installed on high or very high speed platforms over predictable trajectories using optionally DEM (Digital Elevation Model) data of the terrain to estimate the number of stimulated paths and their contributions during the flight. When the instantaneous bandwidth of the signal becomes high (over several hundreds of MHz), one of the most important phenomena to consider is the Doppler spread induced by the channel and traditional narrowband models become useless. This paper presents some results when a time expansion is adopted to emulate the transceiver dynamic and the consequent Doppler spread with the aim of controlling the spectral purity of the emulated propagation channel.

Multisource Energy Harvesting System for a Wireless Sensor Network Node in the Field Environment

This paper presents the design, implementation, and characterization of a hardware platform applicable to a self-powered wireless sensor network (WSN) node. Its primary design objective is to devise a hybrid energy harvesting system to extend the operational lifetime of WSN node after they are deployed in the field environment. Besides the implementation of optimal components (microcontroller, sensor, radio frequency (RF) transceiver, and others) to achieve the lowest power consumption, it is also necessary to consider the sources of energy instead of the frequent recharging or replacement of batteries. Therefore, the platform incorporates a multisource energy harvesting module to collect energy from the surrounding environment, including wind, solar radiation, and thermal energy. The platform also includes an energy storage module through a super-capacitor, RF transceiver module, and the primary microcontroller module. Experimental results showed that the WSN node system with appropriate integration will reserve sufficient energy and meet the long-term power supply requirements of the WSN node without batteries in the field environment. The experimental results and empirical measurements taken over nine days demonstrated that the average daily generating capacity was 7805.09 J, which is far more than the energy consumption of the WSN node (about 2972.88 J).

Toward Automated Manufacturing of RF Coils: Microstrip Resonators for 4.7 T Using 3D-Printed Dielectrics and Conductors

Microstrip transmission line (MTL) resonators are widely used as radio-frequency (RF) transceiver coils in high-field magnetic resonance imaging (MRI). Typically, discrete capacitors are used to tune the MTL resonators to the Larmor frequency and to match to the 50 Ω characteristic impedance of the RF chain. The cost, availability, and labor-intensive work of soldering capacitors on each coil contribute significantly to the expense of RF coil arrays for MRI; therefore, a manufacturing method with lower cost and fewer processing steps is desirable. The additive manufacturing method of rapid prototyping offers a new method to build custom-designed MTL resonators with reduced fabrication steps and, potentially, cost. This feasibility study explores fused deposition modelling to 3D print the MTL resonator structure simultaneously with matching/tuning capacitors and conductors. Typical low-cost 3D printers are capable of printing only polymers, not metal and polymer printing in one machine. In this work, a low-cost 3D printer was modified by adding the capability to print conductive ink and used to print MTL resonators with monolithic parallel-plate capacitors. These integrated capacitors eliminate the repetitive work of soldering, and tuning is achieved by trimming the capacitor plates. In addition, 3D printing allows unconventional designs that minimize the amount of dielectric below the microstrip and, therefore, losses in the substrate. Resulting signal-to-noise ratio values using ink conductors are within 30% of those achieved with copper despite a resistivity that is two orders of magnitude higher. This performance gap can be addressed using newer inks that have much lower resistivity.

Energy Efficiency in Multiple Antenna Machine-Type Communications With Reconfigurable RF Transceivers

In machine-type communication (MTC) networks, each node is equipped with a set of radio-frequency (RF) transceivers, antennas and power source. Besides, wireless nodes are typically battery-powered, whose recharging or replacement is often not viable or even impossible. Therefore, in such systems where energy is at a premium, minimizing power consumption improves energy efficiency and increases battery lifetime. In this paper, a novel energy-saving approach includes in the communication system model the use of reconfigurable RF transceivers. More specifically, the components involved in our power minimization framework are the power amplifier (PA) at the transmitter and the low noise amplifier (LNA) at the receiver, which are the blocks responsible for RF amplification and are on top of power consuming blocks in RF transceivers. Our goal is to show that RF circuits based on multimode operation can significantly improve the energy efficiency. We perform a joint selection of the best operating modes for PA and LNA circuits in different communication scenarios. Results show that by combining PA and LNA operating modes, an improvement of more than 75% in energy efficiency is obtained for multiple antenna communications, when compared to the state-of-the-art literature of non-reconfigurable amplifiers. Besides, we show that adapting spectral efficiency contributes towards improving energy efficiency. In this case, we consider different spectral efficiency values, including the effect that the PA operates at different backed-off power levels. In addition, when comparing single-input single-output (SISO) and multiple-input multiple-output (MIMO) transmission schemes, antenna selection (AS) outperforms the others schemes in terms of energy efficiency for short and moderate distances, but singular value decomposition (SVD) allows for longer communication distances.

Long-Range Wireless Tethering Selfie Camera System Using Wireless Sensor Networks

This paper proposes a wireless sensor network (WSN)-based long-range wireless tethering system (WSN-SELFIE) that implements the novel GIGA-SELFIE system that can take selfies and landscape photos from long distances. In WSN-SELFIE, a low-power WSN using radio frequency (RF) transceiver modules is used to provide long-range communication between a camera and a sensor node. The operating range of WSN-SELFIE can be extended easily by adding more relay nodes to the network. The experimental results demonstrate that WSN-SELFIE performs efficiently in terms of network range, end-to-end network delay, and processing time. Furthermore, it outperforms commercial photography drones and GIGA-SELFIE in terms of cost and runtime.

Exploiting Low Complexity Beam Allocation in Multi-User Switched Beam Millimeter Wave Systems

Switched-beam systems offer a promising solution for realizing multi-user communications at millimeter wave (mmWave) frequencies. A low-complexity beam allocation (LBA) algorithm has been proposed to solve the challenging problem of maximizing sum data-rates. However, there are practical limitations in mmWave systems, such as restrictions in the number of available radio frequency transceiver chains at the base station, sensitivity to sidelobe interference and the beam generation techniques. In this paper, using generalized beam-patterns, we present the maximum sum data-rates achievable in switched-beam mmWave systems compared with fixed-beam systems by applying LBA. Then, the impact on maximum sum data rates of actual beam-patterns, obtained from a practical mmWave lens antenna, which have higher and non-uniform sidelobes compared with the theoretical beams, is assessed. Finally, as a guide for practical wireless system design, benchmarks are established for relative sidelobe levels that provide acceptable sum data-rate performance when considering generalized beam patterns.

A Decentralized Reciprocity Calibration Approach for Cooperative MIMO

As a key technology to improve the coverage and throughput of distributed wireless network, cooperative multiple-input multiple-output (CO-MIMO) system jointly manipulates the precoders of multiple distributed base stations (BSs) to serve multiple mobile stations, simultaneously. However, in time division duplexing mode, independent ambiguity multiplicative factors induced by practical transceiver radio frequency circuits will break the reciprocity between the uplink–downlink channels, resulting in the failure of cooperative precoding in multiple BSs. In this paper, we develop an efficient decentralized reciprocity calibration approach with low overhead and complexity for CO-MIMO systems. Specifically, the calibration problem of CO-MIMO is first modeled as a least square (LS) problem. Based on the decomposition theory, the LS problem is decomposed into a master problem and several subproblems. In order to avoid gathering channel state information from distributed BSs, the master problem is solved jointly and iteratively at the BSs’ side, while the subproblems are solved independently at each BS. According to the decomposition results and the solving strategy, the calibration process is described as a decentralized algorithm. The simulation results demonstrate that better performance could be achieved compared with the centralized approach.

Performance Evaluation of Centralized Reconfigurable Transmitting Power Scheme in Wireless Network-on-chip

Network-on-chip (NoC) is an on-chip communication network that allows parallel communication among all cores to improve inter-core performance. Wireless NoC (WiNoC) introduces long-range and high bandwidth radio frequency (RF) interconnects that can possibly reduce the multi-hop communication of the planar metal interconnects in conventional NoC platforms. In WiNoC, RF transceivers account for a significant power consumption, particularly its transmitter, out of its total communication energy. This paper evaluates the energy and latency performance of a closed loop power management mechanism which enables transmitting power reconfiguration in WiNoC based on number of erroneous received packets. The scheme achieves significant energy savings with limited performance degradation and insignificant impact on throughput.

Design of Wide-band Power Amplifier based on Power Combiner Technique with Low Intermodulation Distortion

RF power amplifiers are one of challenging blocks in designing radio frequency transceivers, this is due to non-linearity behavior of power amplifiers that leads to inter-modulation distortion. This paper presents the design of wide-band power amplifier which combined with parallel coupled line band pass filter at the input and output of power amplifier to allow the only required frequency band to pass through the power amplifier. Class-A topology and ATF-511P8 transistor are used in this design. Advanced Design System software used as a simulation tool to simulate the designed wide-band power amplifier. The simulation results showed an input return loss (S11) which less than -10dB, and gain (S21) is higher than 10 dB over the entire frequency band and considers as flat as well. The designed amplifier is stable over the bandwidth (K>1). Inter-modulation distortion is -56.919dBc which is less than -50dBc with 10dBm input power. The designed amplifier can be used for the microwave applications which include weather radar, satellite communication, wireless networking, mobile, and TV.