Low-power Radio Transceivers Research Articles

The EcoChip 2: An Autonomous Sensor Platform for Multimodal Bio-environmental Monitoring of the Northern Habitat.

This paper presents the EcoChip 2, an autonomous multimodal bio-environmental sensor platform for the monitoring of microorganisms in the northern habitat. The EcoChip 2 prototype includes an array of 96-wells for the continuous monitoring of microbiological growth through a multichannel electrochemical impedance analyzer circuit. In addition, the platform includes luminosity, humidity, temperature sensors and monitoring. The developed electronic board uses an ultra-low-power microcontroller unit, a custom power management unit, a low-power wireless ISM-2.45 GHz transceiver, and a flash memory to accumulate and store the sensor data over extended monitoring periods. When a wireless base station is placed within the transmission range of the EcoChip 2, an embedded low-power wireless transceiver transmits the 96-wells impedance data and the other sensor data stored in the flash memory to the user interface. We present the measured performance of the prototype, along with laboratory test results of bacterial growth measurements inside the 96 wells in parallel. We show that the EcoChip 2 can successfully measure the impedances associated with bacterial growth over several hours using an excitation frequency of 2 kHz with power consumption of 114.6 mW under operating mode.

Potential of Sub-GHz Wireless for Future IoT Wearables and Design of Compact 915 MHz Antenna.

Internet of Things (IoT) technology is rapidly emerging in medical applications as it offers the possibility of lower-cost personalized healthcare monitoring. At the present time, the 2.45 GHz band is in widespread use for these applications but in this paper, the authors investigate the potential of the 915 MHz ISM band in implementing future, wearable IoT devices. The target sensor is a wrist-worn wireless heart rate and arterial oxygen saturation (SpO2) monitor with the goal of providing efficient wireless functionality and long battery lifetime using a commercial Sub-GHz low-power radio transceiver. A detailed analysis of current consumption for various wireless protocols is also presented and analyzed. A novel 915 MHz antenna design of compact size is reported that has good resilience to detuning by the human body. The antenna also incorporates a matching network to meet the challenging bandwidth requirements and is fabricated using standard, low-cost FR-4 material. Full-Wave EM simulations are presented for the antenna placed in both free-space and on-body cases. A prototype antenna is demonstrated and has dimensions of 44 mm × 28 mm × 1.6 mm. The measured results at 915 MHz show a 10 dB return loss bandwidth of 55 MHz, a peak realized gain of 2.37 dBi in free-space and 6.1 dBi on-body. The paper concludes by highlighting the potential benefits of 915 MHz operation for future IoT devices.

A novel power efficient asynchronous time difference of arrival indoor localization system using CC1101 radio transceivers

ABSTRACTThis paper presents a novel 434MHz asynchronous time difference of arrival (A‐TDOA) Indoor Localization System (ILS) using three CC1101 ultra low power radio transceivers from Texas Instruments as asynchronous measuring receivers for time difference of arrival estimation. The three deployed TDOA measuring units are not required to be precisely synchronized in contrast to conventional TDOA localization systems where stringent time synchronization is required between measuring units. Time synchronization is achieved by using a reference transmitter to record the time offset in two TDOA measurements. Actual TDOA measurements are obtained by compensating the time difference measurements for real transmitter using time offsets caused by asynchronous receivers. The implemented system demodulates the obtained time difference pulses to mitigate the clock jitter effect and provides voltage levels corresponding to time differences which are mapped to distance differences. The performance of implemented ILS is evaluated using two sets of real time indoor measurements to estimate the position of mobile transmit node in two dimensional space. The positioning accuracy of implemented system is better than 1.8m along with telemetry data reception capability and low DC power consumption. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:550–555, 2017

DL Prof. Pui-In Mak Gives a Technical Talk Hosted by imec in Leuven, Belgium [Chapters

The IEEE Solid-State Circuits Society (SSCS) Benelux Chapter organized a technical talk on 23 May 2017 given by Pui-In (Elvis) Mak, associate director of research and associate professor, State-Key Laboratory of Analog and Mixed-Signal VLSI, University of Macau, China. Mak is an SSCS Distinguished Lecturer (DL); the program is aimed at disseminating high-quality technical content to members at a local level. In his talk, "Ultra-Low-Power Radios Using Current-Reuse/Function- Reuse/Ultra-Low-Voltage Techniques," Mak discussed the work his research group is doing in Macau, where over 80 researchers focus on analog and mixed-signal ICs for wireless communications, data converters, biomedical and power electronics, and analytical chemistry. He then positioned his work compared to the state of the art on low-power radio transceivers, where his group targets 10x lower power than existing solutions, for comparable battery life times. In this light, he explored several techniques that led to numerous publications in the International Solid-State Circuits Conference as well as IEEE Journal of Solid-State Circuits.

<italic>RTI Goes Wild</italic>: Radio Tomographic Imaging for Outdoor People Detection and Localization

In recent years, Radio frequency (RF) sensor networks have been used to localize people indoor without requiring them to wear invasive electronic devices. These wireless mesh networks, formed by low-power radio transceivers, continuously measure the received signal strength (RSS) of the links. Radio Tomographic Imaging (RTI) is a technique that generates, starting from these RSS measurements, 2D images of the change in the electromagnetic field inside the area covered by the radio transceivers to spot the presence and movements of animates (e.g., people, large animals) or large metallic objects (e.g., cars). Here, we present a RTI system for localizing and tracking people outdoors. Differently than in indoor environments where the RSS does not change significantly with time unless people are found in the monitored area, the outdoor RSS signal is time-variant, e.g., due to rainfall or wind-driven foliage. We present a novel outdoor RTI method that, despite the nonstationary noise introduced in the RSS data by the environment, achieves high localization accuracy and dramatically reduces the energy consumption of the sensing units. Experimental results demonstrate that the system accurately detects and tracks a person in real-time in a large forested area under varying environmental conditions, significantly reducing false positives, localization error and energy consumption compared to state-of-the-art RTI methods.

Intuitive wireless control of a robotic arm for people living with an upper body disability.

Assistive Technologies (ATs) also called extrinsic enablers are useful tools for people living with various disabilities. The key points when designing such useful devices not only concern their intended goal, but also the most suitable human-machine interface (HMI) that should be provided to users. This paper describes the design of a highly intuitive wireless controller for people living with upper body disabilities with a residual or complete control of their neck and their shoulders. Tested with JACO, a six-degree-of-freedom (6-DOF) assistive robotic arm with 3 flexible fingers on its end-effector, the system described in this article is made of low-cost commercial off-the-shelf components and allows a full emulation of JACO's standard controller, a 3 axis joystick with 7 user buttons. To do so, three nine-degree-of-freedom (9-DOF) inertial measurement units (IMUs) are connected to a microcontroller and help measuring the user's head and shoulders position, using a complementary filter approach. The results are then transmitted to a base-station via a 2.4-GHz low-power wireless transceiver and interpreted by the control algorithm running on a PC host. A dedicated software interface allows the user to quickly calibrate the controller, and translates the information into suitable commands for JACO. The proposed controller is thoroughly described, from the electronic design to implemented algorithms and user interfaces. Its performance and future improvements are discussed as well.

Research of Node Energy Consumption Based on Dynamic Power Management in Wireless Greenhouse Control System

The resources of wireless sensor nodes are limited, and the power of nodes is supplied with battery whose capacity is very limited, once the energy of battery is run out, the nodes will lose their effect, so there are serious energy constraint in wireless sensor network. In this paper, the specific energy consumption of sensor nodes is studied by experiments, the energy experimental hardware platform is established with the low power consumption SCM MSP430F135 and wireless transceiver chip CC2420, the relationship of energy consumption and communication distance for nodes is discussed, and the energy management strategy of effective wireless greenhouse monitoring system based on dynamic power management is put forward and discussed, the mobile structure is adopted in the convergent nodes. The experiment and simulation results show that the energy consumption of nodes is proportional to the third power of communication distance, the communication distance of sensor nodes can greatly shorten, and energy consumption is saved.

Calibration Techniques for Low-Power Wireless Multiband Transceiver

The low-power wireless transceiver is the basic silicon building block of wireless sensor networks and the internet of things. In this paper, two digital calibration and compensation techniques for low-power wireless multiband transceiver are presented to adjust the VCO's tuning curves in the frequency synthesizer and eliminate the DC offset voltage in the intermediate frequency (IF) pathway. The fuzzy binary search method is applied to VCO calibration, and gain-based DC offset cancellation (DCOC) is applied. Based on these proposed methods, a multiband transceiver is designed and fabricated in 0.18 μm CMOS with 1.8 V voltage supply. Experimental results show that with 24 MHz system clock, frequency synthesizer calibration can be completed within 450 without requiring any additional calibration prescaler, achieving a calibration resolution of 1 MHz; DC offset voltage can be reduced to less than 3.5 mV for 0 to 60 dB gain, with each calibration process taking only 1.28 ms time. The proposed techniques and corresponding circuits are proved to be cost-efficient while maintaining high performance, which is suitable for multiband and multimode transceiver integration.

Design and Performance Evaluation of On-chip Antenna for Ultra Low Power Wireless Transceiver

In this paper, on-chip antennas applicable to ultra low power wireless transceiver are designed and evaluated. Using <TEX>$0.18{\mu}m$</TEX> SiGe MMIC process, 4 types of antenna with <TEX>$1{\times}1mm^2$</TEX> dimensions are fabricated. The on-wafer measurement in a microwave probe station is conducted to measure the input VSWR and antenna performance of the designed on-chip antenna. Performance evaluation results show that developed antennas can be easily integrated into one-chip RF transceiver for ubiquitous applications, including WPAN and human body communications.

A 10.2 Mbps Pulse Harmonic Modulation Based Transceiver for Implantable Medical Devices

A low power wireless transceiver has been presented for near-field data transmission across inductive telemetry links, which operates based on pulse harmonic modulation (PHM). This PHM transceiver uses on-off keying (OOK) of a pattern of pulses to suppress inter-symbol interference (ISI), and its characteristics are suitable for low-power high-bandwidth telemetry in implantable neuroprosthetic devices. To transmit each bit across a pair of high-Q LC-tank circuits, the PHM transmitter generates a string of narrow pulses with specific amplitudes and timing. Each pulse generates a decaying oscillation at the harmonic frequency that the receiver LC-tank is tuned at, which is then superimposed with other oscillations across the receiver at the same frequency, to minimize the ISI. This allows for reaching high data rates without reducing the inductive link quality factor (to extend its bandwidth), which significantly improves the range and selectivity of the link. The PHM receiver architecture is based on non-coherent energy detection with programmable bandwidth and adjustable gain. The PHM transceiver was fabricated in a 0.5- μm standard CMOS process, occupying 1.8 mm2. The transceiver achieved a measured 10.2 Mbps data rate with a bit error rate (BER) of 6.3×10-8 at 1 cm distance using planar implant sized (1 cm2) figure-8 coils. The PHM transmitter power consumption was 345 pJ/bit and 8.85 pJ/bit at 1 cm and zero link distances, respectively. The receiver dissipates 3 mW at 3.3 V supply voltage.

RadiaLE: A framework for designing and assessing link quality estimators in wireless sensor networks

Stringent cost and energy constraints impose the use of low-cost and low-power radio transceivers in large-scale wireless sensor networks (WSNs). This fact, together with the harsh characteristics of the physical environment, requires a rigorous WSN design. Mechanisms for WSN deployment and topology control, MAC and routing, resource and mobility management, greatly depend on reliable link quality estimators (LQEs). This paper describes the RadiaLE framework, which enables the experimental assessment, design and optimization of LQEs. RadiaLE comprises (i) the hardware components of the WSN testbed and (ii) a software tool for setting-up and controlling the experiments, automating link measurements gathering through packets-statistics collection, and analyzing the collected data, allowing for LQEs evaluation. We also propose a methodology that allows (i) to properly set different types of links and different types of traffic, (ii) to collect rich link measurements, and (iii) to validate LQEs using a holistic and unified approach. To demonstrate the validity and usefulness of RadiaLE, we present two case studies: the characterization of low-power links and a comparison between six representative LQEs. We also extend the second study for evaluating the accuracy of the TOSSIM 2 channel model.

An Integrated CMOS Front-End Receiver with a Frequency Tripler for V-Band Applications

A direct-conversion receiver integrated with the CMOS subharmonic frequency tripler (SFT) for V-band applications is designed, fabricated and measured using 0.13-µm CMOS technology. The receiver consists of a low-noise amplifier, a down-conversion mixer, an output buffer, and an SFT. A fully differential SFT is introduced to relax the requirements on the design of the frequency synthesizer. Thus, the operational frequency of the frequency synthesizer in the proposed receiver is only 20GHz. The fabricated receiver has a maximum conversion gain of 19.4dB, a minimum single-side band noise figure of 10.2dB, the input-referred 1-dB compression point of −20dBm and the input third order inter-modulation intercept point of −8.3dB. It draws only 15.8mA from a 1.2-V power supply with a total chip area of 0.794mm × 0.794mm. As a result, it is feasible to apply the proposed receiver in low-power wireless transceiver in the V-band applications.

Wireless sensor network for volcano environments

Recent technological advances in the areas of microcontroller architectures, sensors and low power wireless transceivers have made it possible to deploy large wireless sensors. There have been numerous research results in the area of power efficiency in the adhoc and wireless sensor networks. In this paper, we propose a new algorithm, which is used to monitor the events about anomalous behaviors of the volcanic edifice. This model uses the sensor devices to monitor the volcano with the help of support node to detect early hazards. It has consumed fewer amounts of the resources while transmitting the data packets from the regular node to the base station. It is compared with the existing algorithms and has shown better results in terms of power consumption and control message packets over the network.

4.8 GHz CMOS Frequency Multiplier Using Subharmonic Pulse-Injection Locking for Spurious Suppression

To realize low-power wireless transceivers, it is necessary to improve the performance of frequency synthesizers, which are typically frequency multipliers composed of a phase-locked loop (PLL). However, PLLs generally consume a large amount of power and occupy a large area. To improve the frequency multiplier, we propose a pulse-injection-locked frequency multiplier (PILFM), where a spurious signal is suppressed using a pulse input signal. An injection-locked oscillator (ILO) in a PILFM was fabricated by a 0.18µm 1P5M CMOS process. The core size is 10.8µm × 10.5µm. The power consumption of the ILO is 9.6µW at 250MHz, 255µW at 2.4GHz and 1.47mW at 4.8GHz. The phase noise is -105dBc/Hz at a 1MHz offset.

17 GHz RF Front-Ends for Low-Power Wireless Sensor Networks

A 17 GHz low-power radio transceiver front-end implemented in a 0.25 mum SiGe:C BiCMOS technology is described. Operating at data rates up to 10 Mbit/s with a reduced transceiver turn-on time of 2 mus, gives an overall energy consumption of 1.75 nJ/bit for the receiver and 1.6 nJ/bit for the transmitter. The measured conversion gain of the receiver chain is 25-30 dB into a 50 Omega load at 10 MHz IF, and noise figure is 12 plusmn0.5 dB across the band from 10 to 200 MHz. The 1-dB compression point at the receiver input is -37 dBm and IIP3 is -25 dBm. The maximum saturated output power from the on-chip transmit amplifier is -1.4 dBm. Power consumption is 17.5 mW in receiver mode, and 16 mW in transmit mode, both operating from a 2.5 V supply. In standby, the transceiver supply current is less than 1 muA.

A 2.4 GHz low power wireless transceiver analog front-end for endoscopy capsule system

This work presents the design and implementation of a 2.4 GHz low power wireless transceiver analog front-end for the endoscopy capsule system in 0.25 μm CMOS. The prototype integrates a low-IF receiver analog front-end (low noise amplifier, double-balanced down-converter, band-pass-filtered AGC loop, and ASK demodulator) and a direct-conversion transmitter analog front-end (20 MHz IF PLL with well-defined amplitude control circuit, ASK modulator, up-converter, and output buffer) on a single chip together with one integrated RF oscillator and two LO buffers. Trade-off has been made over the design boundaries of the different building blocks to optimize the overall system performance. All building blocks feature the circuit topologies that enable comfortable operation at low power consumption. As a result, the IC works at a 2.5 V power supply, while only consuming 15 mW in receiver (RX) mode and 14 mW in transmitter (TX) mode. To build a complete transceiver for the endoscopy capsule system, only an antenna, a duplexer, and a digital controller are needed besides the presented analog front-end chip.

MoteTrack: a robust, decentralized approach to RF-based location tracking

In this paper, we present a robust, decentralized approach to RF-based location tracking. Our system, called MoteTrack, is based on low-power radio transceivers coupled with a modest amount of computation and storage capabilities. MoteTrack does not rely upon any back-end server or network infrastructure: the location of each mobile node is computed using a received radio signal strength signature from numerous beacon nodes to a database of signatures that is replicated across the beacon nodes themselves. This design allows the system to function despite significant failures of the radio beacon infrastructure. In our deployment of MoteTrack, consisting of 23 beacon nodes distributed across our Computer Science building, we achieve a 50th percentile and 80th percentile location-tracking accuracy of 0.9 and 1.6 m respectively. In addition, MoteTrack can tolerate the failure of up to 60% of the beacon nodes without severely degrading accuracy, making the system suitable for deployment in highly volatile conditions. We present a detailed analysis of MoteTrack's performance under a wide range of conditions, including variance in the number of obstructions, beacon node failure, radio signature perturbations, receiver sensitivity, and beacon node density.

GPSの時刻同期信号を利用した海上における位置情報通信システムに関する研究

The position communication system to rescue a drifting diver in marine has been studied. The practical equipment, however, has not developed, as there still exist several subjects to be solved. There are some restrictions posed to the equipment to be used in marine, such as the size, reliability of the position, and communication distance of low power radio regulated by the law. We adopted a low power radio transceiver to avoid the regulation and a spread-spectrum system in order to extend the communication distance. We are trying to adjust the PN code is generated at both transmitter and receiver to obtain further extension of the communication distance by using the PPS signal by a GPS receiver. At the transmission side, the data and the PN code are triggered by PPS signal every second. They are multiplied each other. At the receiver side, down conversion and A/D conversion are performed in the RF section of a receiver, and digitized signal was introduced into FPGA. The signal is despread by the PN code synchronously generated with the PPS signal and the data are obtained. The preliminary experiment shows a possibility of 5 to 10 times longer distance communication than the conventional low power radio transceiver.

Multiplier-Free Bandpass Channelizer for Undersampled Applications

Today, there is a strong motivation to increase the digital content of low-power wireless transceivers. Direct data conversion is often not possible, or practical, at high radio frequencies. In such instances, undersampling analog-to-digital converters (ADCs) are often used to alias information, residing above the ADC's Nyquist frequency, down to baseband as a set of nonoverlapping subbands. In this paper a low-complexity, programmable, band-selectable channelizer (a.k.a., digital downconverter) is presented that can efficiently access specific subbands from an undersampled signal space.

The Secret Life of Birds

This paper presents a wireless sensor network being used for the study of Leach's storm petrel on Great Duck Island, Maine, USA. The petrel-watching apparatus consists of a distributed system of devices called 'motes', each having the dual functions of data collection and communication. For the former role, the mote contains application-specific sensors and signal-processing hardware; for the latter, the mote has a low-power radio transceiver. When the motes are networked together, each simultaneously collects data from its immediate surroundings and passes its own and other motes' data through the network.