RF Transceiver Research Articles

Real-Time Use-Aware Adaptive RF Transceiver Systems for Energy Efficiency Under BER Constraints

Modern radio front ends are required to operate over diverse channel conditions requiring the incorporation of significant performance overheads into their design. This results in significantly higher power consumption over most of the operational period since the worst case channels are not statistically prevalent. Adaptive systems solve this problem by adapting the performance and power consumption depending on channel conditions. In this paper, it is demonstrated that depending upon the throughput requirements of the system multiple low-power adaptation modes can be designed. These modes ensure either highest throughput operation or lowest energy-per-bit operation. The operation of these modes is demonstrated in simulation using multiple-input-multiple-output (MIMO) receiver and transmitter front ends. Subsequently, the concepts are demonstrated in hardware for both MIMO and single-input-single-output front ends.

Ultra low-power transceiver with novel FSK modulation technique and efficient FSK-to-ASK demodulation.

Energy-efficient and high-data rate are desired in biomedical devices transceivers. A high-performance transmitter (Tx) and an ultra-low-power receiver (Rx) dedicated to medical implants communications operating at Industrial, Scientific and Medical (ISM) frequency band are presented. Tx benefits from a new efficient Frequency-Shift Keying (FSK) modulation technique which provides up to 20 Mb/s of data-rate and consumes only 0.084 nJ/b validated through fabrication. The receiver consists of an FSK-to-ASK conversion based receiver with OOK fully passive wake-up device (WuRx). This WuRx is battery less with energy harvesting technique which plays an important role in making the RF transceiver energy-efficient. The Rx is achieved with a reduced hardware architecture which does not use an accurate local oscillator, high-Q external inductor and I/Q signal path. The Rx shows -78 dBm sensitivity for 8 Mbps data rate while consuming 639 μW. The proposed circuits are implemented in IBM 0.13 μm CMOS technology with 1.2 V supply voltage.

Survey on a Novel Wireless Sensor Network Communication at 433MHz Frequency

Wireless underground sensor networks (WUSN) are a promising new technology for monitoring soil information with a high spatial and temporal resolution for large areas. However, the significantly high attenuation caused by soil is the main challenge for the feasibility of WUSN. Recent theoretical results highlight the potential of smaller attenuation rates with the use of smaller radio frequencies. In this paper, experimental measurements have been conducted with commodity sensor nodes at the frequency of 433 MHz. Experiments are run to examine the received signal strength of correctly received packets and the packet error rate for a communication link. The tests show the potential feasibility of the WUSN with the use of powerful RF transceivers at 433MHz frequency. Moreover, we also illustrate a classification for wireless underground sensor network communication. Finally, we conclude that the effects of burial depth, inter-node distance and volumetric water content of the soil on the signal strength and packet error rate.

CMOS transceiver with high input dynamic range and wide modulation-depth for RFID and NFC readers

This paper presents a fully integrated CMOS RF transceiver for radio-frequency identification (RFID) and near-field communication (NFC) readers. The receiver achieves high sensitivity using a low-noise amplifier (LNA) and enlarges the input dynamic range by employing a variable attenuator in front of the LNA. The variable attenuator is self-controlled by sensing the input signal strength with a power level detector. The transmitter incorporates a digitally controlled pulse-width modulator using a delay-locked loop to supports various amplitude-shift keying modulation depths. The transceiver is implemented using a standard 0.18-μm CMOS process. The measurement results prove that the proposed transceiver operates successfully in both RFID and NFC modes.

A Low-Cost UHF RFID System With OCA Tag for Short-Range Communication

An ultrahigh-frequency RF identification system, consisting of a fully integrated tag and a special reader, has been developed for short-range and harsh size requirement applications. The system is fabricated in the standard 0.18-μm CMOS process. The whole tag chip with an antenna, an analog front end, a baseband, and memory takes up an area of 0.36 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , which is smaller than other reported tags with an on-chip antenna (OCA) using the standard CMOS process. A self-defined protocol is proposed to reduce the power consumption and minimize the size of the tag. A specialized system-on-a-chip reader system, consisting of RF transceiver, digital baseband, MCU, and host interface, supports both the self-defined and International Standards Organization 18000-6 C protocols. Its power consumption is about 500 mW, which is much lower than other reported readers considering the transmission power. Measurement results show that the system's reading range is 2 mm with a 20-dBm reader output power. In addition, it has been verified that the data stored in the OCA tag embedded in a pearl can be successfully read out. With an inductive antenna printed on a paper substrate around the OCA tag, the reading range can be extended from several centimeters to meters depending on the shape and size of the inductive antenna.

Low Phase Noise CMOS VCO with Hybrid Inductor

A low phase noise CMOS voltage controlled oscillator(VCO) for multi-band/multistandard RF Transceivers is presented. For both wide tunability and low phase noise characteristics, Hybrid inductor which uses both bondwire inductor and planar spiral inductor in the same area, is proposed. This approach reduces inductance variation and presents high quality factor without custom-designed single-turn inductor occupying large area, which improves phase noise and tuning range characteristics without additional area loss. An LC VCO is designed in a 0.13um CMOS technology to demonstrate the hybrid inductor concept. The measured phase noise is -121dBc/Hz at 400KHz offset and -142dBc/Hz at 3MHz offset from a 900MHz carrier frequency after divider. The tuning range of about 28%(3.15 to 4.18GHz) is measured. The VCO consumes 7.5mA from 1.3V supply and meets the requirements for GSM/EDGE and WCDMA standard.

저 전력 무선 센서 네트워크를 위한 시스톨릭 구조 설계 및 구현

In this paper, we propose a unique systolic structure and communication algorithm that maintains a solid link between nodes using synchronous digital communication and enables low power communication. This system was designed by using CC2500 RF transceiver, CC2590 RF front end and C8051F330 low power microcontroller. The measurement of power consumption in the network link shows below 400μW in data transfer rate 320bps. The system constitutes the base unit of low power wireless network that was composed of each seven link nodes having eight sensor nodes. Results of the experiments show that link nodes using a 4Ah battery could operate over 3 years without replacement.

Development of a Microcontroller-based Wireless Accelerometer for Kinematic Analysis

Wireless sensor networks (WSNs) allow real-time measurement and monitoring with less complexity and more efficient in terms of obtaining data when the subject is in motion. It eliminates the limitations introduced by wired connections between the sensors and the central processing unit. Although wireless technology is widely used around the world, not much has been applied for education. Through VISSER, a low cost WSN using nRF24L01+ RF transceiver that is developed to observe and analyze the kinematics of a moving object is discussed in this paper. Data acquisition and transmission is realized with the use of a low power and low cost microcontroller ATtiny85 that obtains data from the ADXL345 three-axis accelerometer. An ATtiny85 also controls the receiving module with a UART connection to the computer. Data gathered are then processed in an open-source programming language to determine properties of an object’s motion such as pitch and roll (tilt), acceleration and displacement. This paper discusses the application of the developed WSN for the kinematics analysis of a toy car moving on flat and inclined surfaces along the three axes. The developed system can be used in various motion detection and other kinematics applications, as well as physics laboratory activities for educational purposes.

생체 모방형의 아쿠아리움 관상어 로봇 개발

ABSTRACT In this paper, the designed fish robots DOMI ver1.0 is researched and development for aquarium underwater robot. The presented fish robot consists of the head, 1’st stage body, 2nd stage body and tail, which is connected two point driving joints. The model of the robot fish is analysis to maximize the momentum of the robot fish and the body of the robot is designed through the analysis of the biological fish swimming. Also, Lighthill was applied to the kinematics analysis of robot fish swimming algorithms, we are applied to the approximate method of the streamer model that utilizes techniques mimic the biological fish. The swimming robot has two operating mode such as manual and autonomous operation modes. In manual mode the fish robot is operated to using the RF transceiver, and in autonomous mode the robot is controlled by microprocessor board that is consist PSD sensor for the object recognition and avoidance. In order to the submerged and emerged, the robot has the bladder device in a head portion. The robot gravity center weight is transferred to a one-axis sliding and it is possible to the submerged and emerged of DOMI robot by the breath unit. It was verified by the performance test of this design robot DOMI ver1.0. It was confirmed that excellent performance, such as driving force, durability and water resistance through the underwater field test.Keywords:Fish Robot, Autonomous Bio-Mimetic Ornamental, Aquarium Fish Robotic, Under Water Robot, Lighthill Dynamics Analysis

A UHF RFID system with on-chip-antenna tag for short range communication

A UHF RF identification system based on the 0.18 μm CMOS process has been developed for short range and harsh size requirement applications, which is composed of a fully integrated tag and a special reader. The whole tag chip with the antenna takes up an area of 0.36 mm2, which is smaller than other reported tags with an on-chip antenna (OCA) using the standard CMOS process. A self-defined protocol is proposed to reduce the power consumption, and minimize the size of the tag. The specialized SOC reader system consists of the RF transceiver, digital baseband, MCU and host interface. Its power consumption is about 500 mW. Measurement results show that the system's reading range is 2 mm with 20 dBm reader output power. With an inductive antenna printed on a paper substrate around the OCA tag, the reading range can be extended from several centimeters to meters, depending on the shape and size of the inductive antenna.

Toward a Wireless Electronic Capsule With Microsensors for Detecting Dysfunction of Human Gastric Motility

This paper presents a method for detecting human gastric-motility dysfunction using a wireless electronic capsule. The capsule's main components include an application-specific integrated circuit, three sensors (temperature, pH, and pressure), an RF transceiver, and batteries. In addition, a portable data recorder was developed to receive and store the data transmitted by the wireless capsule. In particular, experimental results indicated that the maximum error and measuring range of the pressure sensor were 0.15 and 90-120 kPa, respectively. Using pressure data from the human stomach, a joint algorithm based on phase space reconstruction and independent component analysis was applied in the analysis of gastric motility. Implementation results showed that this joint algorithm could effectively obtain the components of pressure data for the human stomach that were caused by breathing, movement, contractions of abdominal muscles, and electrogastrogram. In 24 human experiments, poor gastric motility (functional dyspepsia and delayed gastric emptying) was identified with a recognition rate of nearly 80%. In particular, interdigestive motor complex and digestive motor complex related to human gastric motility were also identified.

RC-MAC: A Receiver-Centric MAC Protocol for Event-Driven Wireless Sensor Networks

Event-driven wireless sensor networks (WSNs) usually operate under light traffic load. However, when an event is detected, a large number of packets may be generated. A MAC protocol designed for this kind of WSNs should be able to swiftly adapt to the two conditions. Most WSN MAC protocols are optimized for light traffic for the energy efficiency consideration. In this paper, we propose a novel receiver-centric MAC protocol called RC-MAC that seamlessly integrates duty cycling and receiver-centric scheduling, providing high throughput without sacrificing the energy efficiency. To handle bursty traffic triggered by an event, RC-MAC takes advantage of the underlying data gathering tree structure of WSNs and the multichannel technique supported by current IEEE 802.15.4 RF transceivers to assist scheduling of medium access. The throughput is improved in two phases with receiver-centric medium access scheduling and distributed channel assignment. First, on a data gathering tree, a receiver is able to coordinate the medium access of multiple senders so as to reduce collisions and achieve high throughput. Second, different receivers coordinate their senders in different channels and the throughput is further improved by allowing parallel data gathering. Observing packet processing time on low cost sensor nodes, we design a scheduling pattern that ensures fairness between source nodes without sacrificing the throughput. We evaluate the performance of our RC-MAC through measurements of an implementation in TinyOS on TelosB motes and extensive ns-2 simulations. Compared with contention-based and scheduling-based MAC protocols, we show that the throughput and the fairness under heavy traffic load are significantly improved by the receiver-centric scheduling. Due to the high throughput, the energy efficiency is also improved.

Gesture Controlled Robot using MEMS Accelerometer for Eradication of Weeds

Robots are playing a vital role in today's industrial automation and monitoring system. As technology developed these robots have increased their applications and functionality. Working robots will cooperate to the people makes the work more effortless and uncomplicated. This paper provides 4 different gestures for controlling the robots, i.e., forward, backward, left, right. For cutting weeds a gripper concept using buttons is anticipated. These movements are given by the user using MEMS accelerometer. The MEMS accelerometer will be set to the hand. Whenever the hand moves in some direction, the mechanical movement of the hand will be recognized by MEMS. MEMS translate this mechanical hand movement into equivalent electrical signals and send it to the PIC microcontroller. The PIC microcontroller at the transmitter side sends control signals to the receiver side through RF TRANSCEIVER. The controller at the receiver area receives these signals and gives direction to the robot. This type of robot is used in the crop filed to cut the weeds as per the user command.

Wireless network of controlled energy-efficient LED lighting source

The development and implementation results for a branching network of controlled LED light sources with the architecture of standard IEEE 802.15.4 are presented. The network includes a physical PHY layer as a RF transceiver with low-level control mechanism and channel sublayer MAC, providing an access to the physical channel.

Design and Implement of an Indoor Location System Based on Active RFID

This paper presents an indoor location system. The system is comprised of a RFID reader and several low-power active RFID tags.This designed active RFID tag consists of an ultra low power micro-controller, a low power RF transceiver, micro-strip antenna and an on-board battery. The indoor location system uses a RSSI-based ranging technology location algorithm. The experimental results show that the system is a good location system of high precision. And thanks to the advantage of these low-power active RFID tags, this system can be implemented simply for different applications.

An IR-UWB RF transceiver for high-rate WBAN applications

An IR-UWB RF transceiver for high-rate WBAN applications

A wireless capsule system with ASIC for monitoring the physiological signals of the human gastrointestinal tract.

This paper presents the design of a wireless capsule system for monitoring the physiological signals of the human gastrointestinal (GI) tract. The primary components of the system include a wireless capsule, a portable data recorder, and a workstation. Temperature, pH, and pressure sensors; an RF transceiver; a controlling and processing application specific integrated circuit (ASIC); and batteries were applied in a wireless capsule. Decreasing capsule size, improving sensor precision, and reducing power needs were the primary challenges; these were resolved by employing micro sensors, optimized architecture, and an ASIC design that include power management, clock management, a programmable gain amplifier (PGA), an A/D converter (ADC), and a serial peripheral interface (SPI) communication unit. The ASIC has been fabricated in 0.18- μm CMOS technology with a die area of 5.0 mm × 5.0 mm. The wireless capsule integrating the ASIC controller measures Φ 11 mm × 26 mm. A data recorder and a workstation were developed, and 20 cases of human experiments were conducted in hospitals. Preprocessing in the workstation can significantly improve the quality of the data, and 76 original features were determined by mathematical statistics. Based on the 13 optimal features achieved in the evaluation of the features, the clustering algorithm can identify the patients who lack GI motility with a recognition rate reaching 83.3%.

A 1.2 nJ/bit 2.4 GHz Receiver With a Sliding-IF Phase-to-Digital Converter for Wireless Personal/Body Area Networks

This paper presents an ultra-low-power (ULP) 2.4GHz RX for short-range wireless personal and body-area networks. In such applications, the RF transceiver consumes up to 90% of the total battery energy in a remote sensor node. In order to extend the operation lifetime, it is a primary design goal for such transceivers to improve the energy efficiency, expressed as power consumption/data-rate, to below 1nJ/bit. Although energy-detection or superregenerative ASK RXs [1] are very efficient, they are vulnerable to interference and this leads to a poor quality of the wireless link in a crowded 2.4GHz ISM band. On the other hand, FSK/PSK-type modulations are popular in the target applications because of their power-efficient hardware and higher immunity to interference. They are also widely adopted in many short-range wireless standards like IEEE802.15.4 and Bluetooth Smart. Thanks to the constant-envelope nature of FSK/PSK-type modulations, e.g., HS-OQPSK, they only modulate data on the carrier frequency or phase, so the TX hardware can be simplified, while the efficiency can be enhanced by driving the circuits into a saturated mode, e.g., PLL-based FSK TXs [2,5]. Similarly, in the RX counterpart, instead of processing the signal in the I/Q domain, it can be demodulated in the phase domain by using a phase-ADC [3]. However, such approach still requires a power-hungry high-frequency multi-phase LO generation and “2-dimensional” downconversion and filtering circuits. In the single-channel RX of [4], the VCO is part of the carrier-recovery and phase-demodulation loop. Therefore, the VCO frequency can be easily “pulled away” by an interferer, and the RX has a poor sensitivity because phase noise is deteriorated by the signal chain when input level is low.

New antenna technology for 5G wireless communications [Guest editors' introduction

What is the fifth generation (5G) wireless communication? Nobody could tell us an exact definition at present. However, some emerging and potential technologies have attracted more and more attention. Of which, massive MIMO and millimeter wave technologies are considered to be the key technologies for 5G wireless communications. Traditionally, the antenna in mobile communication systems is a passive element and generally is separated from the RF transceivers. For massive MIMO, at either lower microwave band or millimeter wave band, the antenna will be seamlessly integrated with RF transceivers and even with RoF or ADC (DAC) and E/O (O/E). Therefore, the antenna for 5G wireless communications will have distinct characteristics compared to traditional antennas. This special issue will focus on the recent research advances in 5G antennas.

Green Communications: Digital Predistortion for Wideband RF Power Amplifiers

The RF PA, as one of the most essential components in any wireless system, suffers from inherent nonlinearities. The output of a PA must comply with the linearity requirement specified by the standards. Due to its satisfactory linearization capability, DPD has been widely accepted as one of the fundamental units in modern and future wideband wireless systems. With the help of this flexible digital technology, the inherent linearity problem of PAs operating in the saturation region can be significantly improved, which enables us, the wireless engineers, to create more suitable RF transceiver architectures to provide wireless access with better user experience (linearity perspective) and less power waste (power efficiency perspective). This moves us one more step towards the ultimate green communications. In this article, we discussed the DPD techniques in the context of linearizing nonlinear RF PAs. As the computing-horsepower and the transistor-density of digital IC increases while the cost per transistor decreases, the concept that uses digital enhancement techniques to eliminate active analog imperfects will gain more attention from both industry and academia.