RF Transceiver Research Articles

A CMOS UHF Harmonic Rejection Transceiver With 2-D LO Phase Calibration for TV White Space Applications

A CMOS ultra-high frequency-band RF transceiver based on 8-phase harmonic rejection mixer (HRM) architecture with an integrated fractional-N PLL synthesizer is presented for television white space applications. A divide-by-2 and a phase interpolator (PI) circuit are used to generate the 8-phase LO signals for the HRM. The synthesizer output frequency is two times higher than the desired band frequency. The PI is tunable to allow 7-bit calibration of 45° and 135° LO phases. A systematic 2-D calibration scheme that is applicable to both the receiver and transmitter is described. It is demonstrated that only 45° and 135° LO phase calibration is sufficient to minimize the third and fifth harmonic components. Implemented in 0.18- $\mu$ m CMOS, the RF transceiver covers 470–806 MHz, achieving the third and fifth harmonic suppressions below −48 and −56 dBc at the receiver, and the harmonic emission below −51 dBc at the transmitter.

전원 스위칭을 이용한 저전력 소형무인기용 RF 송수신기 설계

In this paper, we designed a RF transceiver for small unmanned aerial vehicle(UAV) using power switching method. To apply for the UAV, several characteristics such as size, weight, and power consumption are very important. To reduce power consumption, we propose a new power switching method. Using the proposed method, we fabricated the RF transceiver needed to establish the data link for a small UAV. The fabricated RF transceiver shows an output power of +25 dBm, a noise figure of 4.56 dB and a received signal strength of −100 dBm. By performing power measurement of proposed switching method, 25 % of power could be reduced. The size of the fabricated RF transceiver is 100×60×5.7 mm3 and the weight is as small as 38 g.

Rotman Lens Based Hybrid Analog–Digital Beamforming in Massive MIMO Systems: Array Architectures, Beam Selection Algorithms and Experiments

Hybrid analog-digital beamforming is a well-known cost-efficient signal processing method for massive MIMO systems. In this paper, we propose a hybrid beamforming massive MIMO system based on Rotman lens analog beamforming with beam selection and digital beamforming. Rotman lens is a low-cost true-time-delay analog beamforming network supporting wide bandwidth signals, which is thus more attractive than the analog beamforming networks based on conventional high-cost phase shifters. To study our system based on Rotman lens, we first examine two potential array architectures, i.e., full-array and subarray architectures, concerning the RF design feasibility, insertion loss, and system scalability. Since the beam selection is required in our system, we propose two beam selection algorithms, i.e., greedy search-based method and branch- and bound-based method, aiming to optimize the hybrid beamforming system in terms of error-rate performance for both the full-array and subarray architectures. To validate our system in practice, the proposed system is also investigated and verified experimentally. In particular, we design and fabricate a sample of Rotman lens operating in the 5-GHz band, whose measured results agrees well with the computer simulation results. The measurement results are incorporated into the Monte-Carlo simulation with the proposed beam selection algorithms to study the error-rate performance. Our simulation results show that the hybrid beamforming system using the low-cost Rotman lens has performance comparable to that of the system using the high-cost phase shifters, and exhibits wideband capability and superior performance over the small-scale MIMO system under the same number of RF transceivers.

Chronic stress and suboptimal nutrition is associated with chromosome instability in dementia family carers

With the proliferation of wireless networks, there is a need for more compact, low-cost, power-efficient transceivers that are capable of supporting the comprehensive communication standards including GSM, WLAN, Bluetooth, GNSS, FM, and 4G of 3GPP cellular. To accommodate the ever-increasing appeal of higher data throughputs within the crowded frequency spectrum of 500 MHz to 6 GHz, these communication standards utilize extremely efficient complex-modulated baseband signals in which their related bandwidths can be as wide as 160 MHz. Moreover, due to the extreme cost pressures of consumer electronics, migration to a more advanced nanometer-scale CMOS process, which was primarily developed for fast and low-power digital circuits operating at low supply voltages, is necessary. Additionally, this fast-evolving CMOS technology unfolds the possibility of integrating the entire radio including the DSP as well as the RF transmitter and receiver with just one single chip. Conventionally, the RF transmitter could not be implemented as a fully integrated circuit like the other building blocks of the corresponding RF transceiver could be as it consists of the bulky DACs, filters, mixers, and the power amplifier (PA). As a consequence of the existing previously mentioned components, especially the PA, the RF transmitter is the most power consuming element of the RF transceivers. This part affects EVM, out-of-band emission and, most significantly, the battery lifetime of the mobile devices.

Novel Active Bandpass Switchplexer for RF Transceiver Front-End Applications

In this paper, the design of RF transceiver front-end using a novel multifunction microwave circuit is proposed. By designing one arm of the proposed active bandpass switchplexer as a bandpass power amplifier (PA) and the other arm as a single-to-balanced bandpass low-noise amplifier (LNA), the resulted multifunctional microwave filtering device thus effectively integrates the functions of single-pole-double-throw RF switch, bandpass filter, balun, PA, and LNA. In this way, all the function blocks between the antenna and up/down converters of a single-band time-division duplex transceiver front-end can be integrated into a single circuit. Compared to the previous works on multifunction microwave circuit designs, the proposed active bandpass switchplexer features the highest number of integrated functions. A printed circuit board-based design example of the proposed active bandpass switchplexer is presented to validate the proposed design concept and to demonstrate the performance achieved.

An 802.11a/b/g/n/ac WLAN Transceiver for $2 \times 2$ MIMO and Simultaneous Dual-Band Operation With +29 dBm $\text{P}_{\mathrm {sat}}$ Integrated Power Amplifiers

This paper describes the first dual-band MIMO 802.11a/b/g/n/ac WLAN RF transceiver capable of simultaneous dual-band operation. The measured receiver sensitivity of 2 GHz at 54 Mbps is −78.3 dBm and of 5 GHz for VHT80 is −66 dBm. The 802.11ac $2 \times 2$ MIMO 20-MHz MCS0 2 and 5 GHz receiver sensitivity levels are −96 and −95.5 dBm, respectively. Integrated power amplifiers with $P_{\mathrm{sat}}$ of +29 dBm enable the 2-GHz transmitters to achieve TX output power of +23.5 dBm at 54-Mbps 64-quadratic-amplitude modulation (QAM). The 5-GHz transmitters achieve +17 dBm output for VHT80 256-QAM. This WLAN-BT connectivity system-on-chip is implemented in 40-nm CMOS technology.

Speed Dictators For Forced Speed Limit At Critical places Using Low Cost RF Transceivers with Integrated Immobilizer

An intention to work on the topic of this nature is emanated from the interest to explore alternative technological solution to achieve effective speed control. Objective of the study is to design and develop a new system that can effectively detect speed violations on the road and supports the driver to obey traffic rules while driving by maintaining the speed according to the speed limit prescribed. In the present day scenario traffic rules are frequently violated by the drivers and over speeding occur due to bad driving behavior. So, a driver assistance system is provided to prevent over speeding, violation of road rules and also to display alert messages. The proposed system has an alerting, recording and reporting system for over speed violation management. The proposed system automatically controls the speed of vehicles at speed restricted areas such as school and hospitals. The main reason behind developing this project is to avoid accident of vehicles at speed limit zones and also to help the passengers to cross the road safely without facing any danger from high speed vehicles. Normally, the vehicle drivers not consider the passengers who crosses road in speed limited areas and drive their vehicles at high speed. So, now accidents are increasing in these areas. The traffic police control the traffic but they are not able to avoid the accidents completely. To solve this problem we developed the proposed system, which not interrupts the vehicle drivers and controls the speed of the vehicles up to certain limit in these speed restricted zones. The LCD displays the lane speed limit. Even though the traffic police controls them we cannot achieve full response from them. Also it is not possible to monitor those areas at all time to regulate their speed. This project is very useful for the common people to walk safely in the roads of speed restricted zones¬¬ and also drivers can ride their vehicles safely.

Evaluation of communication in wireless underground sensor networks

Wireless underground sensor networks (WUSN) are an emerging area of research that promises to provide communication capabilities to buried sensors. In this paper, experimental measurements have been conducted with commodity sensor motes at the frequency of 2.4GHz and 433 MHz, respectively. 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 in communication of WUSN.

Wireless networks of energy efficient dynamically controlled LED sources

The paper presents the results of development and practical implementation of wireless networks of controlled spectrally tunable light emitting diode (LED) light sources using RF transceivers operating in the unlicensed frequency bands of 868 and 2400MHz. Such sources allow synthesizing either a white light with various color temperatures or a colored light with different tints; they are of significant interest in connection with general lighting and with some special applications. The problems of practical realization of light sources and their optimization with respect to luminous efficiency, dynamic range and the distance of wireless control have been investigated.

A Novel Solar and Electromagnetic Energy Harvesting System With a 3-D Printed Package for Energy Efficient Internet-of-Things Wireless Sensors

This paper discusses the design of a novel dual (solar + electromagnetic) energy harvesting powered communication system, which operates at 2.4 GHz ISM band, enabling the autonomous operation of a low power consumption power management circuit for a wireless sensor, while featuring a very good “cold start” capability. The proposed harvester consists of a dual port rectangular slot antenna, a 3-D printed package, a solar cell, an RF-dc converter, a power management unit (PMU), a microcontroller unit, and an RF transceiver. Each designed component was characterized through simulation and measurements. As a result, the antenna exhibited a performance satisfying the design goals in the frequency range of 2.4–2.5 GHz. Similarly, the designed miniaturized RF-dc conversion circuit generated a sufficient voltage and power to support the autonomous operation of the bq25504 PMU for RF input power levels as low as −12.6 and −15.6 dBm at the “cold start” and “hot start” condition, respectively. The experimental testing of the PMU utilizing the proposed hybrid energy harvester confirmed the reduction of the capacitor charging time by 40% and the reduction of the minimum required RF input power level by 50% compared with the one required for the individual RF and solar harvester under the room light irradiation condition of 334 lx.

Smart Random Neural Network Controller for HVAC Using Cloud Computing Technology

Smart homes reduce human intervention in controlling the heating ventilation and air conditioning (HVAC) systems for maintaining a comfortable indoor environment. The embedded intelligence in the sensor nodes is limited due to the limited processing power and memory in the sensor node. Cloud computing has become increasingly popular due to its capability of providing computer utilities as internet services. In this study, a model for the intelligent controller by integrating internet of things (IoT) with cloud computing and web services is proposed. The wireless sensor nodes for monitoring the indoor environment and HVAC inlet air, and wireless base station for controlling the actuators of HVAC have been developed. The sensor nodes and base station communicate through RF transceivers at 915 MHz. Random neural network (RNN) models are used for estimating the number of occupants, and for estimating the predicted-mean-vote-based setpoints for controlling the heating, ventilation, and cooling of the building. Three test cases are studied (Case 1—Data storage and implementation of RNN models on the cloud, Case 2—RNN models implementation on base station, Case 3—Distributed implementation of RNN models on sensor nodes and base stations) for determining the best architecture in terms of power consumption. The results have shown that by embedding the intelligence in the base station and sensor nodes (i.e., Case 3), the power consumption of the intelligent controller was 4.4% less than Case 1 and 19.23% less than Case 2.

FPGA-based wireless sensor nodes for vibration monitoring system and fault diagnosis

The use of wireless sensor networks (WSN) in different applications and domains is constantly growing. In the industrial applications, especially the monitoring of rotating machinery, WSN technology is mature enough to be considered as the most appropriate alternative to traditional wired systems due to a specific constraints related to the art itself. Given the importance of this area, the sensor nodes constituting industrial wireless sensor networks must meet some exigencies such as secure data transmission, high sampling rate and synchronous data acquisition, which require such minimum level of data processing capabilities. In the present work, we developed an FPGA-based wireless sensor node for a machine vibration monitoring system and fault diagnosis. The proposed wireless node is based on Xilinx Artix-7 XC7A35T FPGA circuit, connected via a Serial Peripheral Interface (SPI) to the RF transceiver nRF24L01+ as low-cost and low-power wireless radio module. An additional AES (Advanced Encryption Standard) block is implemented as custom IP core so that the transmitted data is highly secured. A solution is proposed in order to improve the synchronization using a sink node as master to trigger a simultaneous data acquisition in the network. To validate the node, experimental tests are performed on a rotating machine test bench with unbalance fault. The measurement results showed that the designed node met the requirements for synchronous data acquisition where a minimal error of 60 ns is reached.

NMR measurement system including two synchronized ring buffers, with 128 rf coils for in situ water monitoring in a polymer electrolyte fuel cell.

A small radio-frequency (rf) coil inserted into a polymer electrolyte fuel cell (PEFC) can be used to acquire nuclear magnetic resonance (NMR) signals from the water in a membrane electrode assembly (MEA) or in oxygen gas channels in the PEFC. Measuring the spatial distribution of the water in a large PEFC requires using many rf probes, so an NMR measurement system which acquires NMR signals from 128 rf probes at intervals of 0.5 s was manufactured. The system has eight rf transceiver units with a field-programmable gate array (FPGA) for modulation of the excitation pulse and quadrature phase detection of the NMR signal, and one control unit with two ring buffers for data control. The sequence data required for the NMR measurement were written into one ring buffer. The acquired NMR signal data were then written temporarily into the other ring buffer and then were transmitted to a personal computer (PC). A total of 98 rf probes were inserted into the PEFC that had an electrical generation area of 16 cm × 14 cm, and the water generated in the PEFC was measured when the PEFC operated at 100 A. As a result, time-dependent changes in the spatial distribution of the water content in the MEA and the water in the oxygen gas channels were obtained.

RF Transceiver Circuit FPGA Program Design and Development

RF Transceiver Circuit FPGA Program Design and Development

Wireless RF systems modelling using SystemC

In this paper, we present a method to realize wireless communication system modelling using SystemC at different levels of abstraction. The objective of the simulations is to analyze the system-level performance with considering circuit-level specifications by integrating the necessary circuit-level measurements (or Spice simulation) into the system-level models. Bluetooth Low Energy (BLE) RF Transceiver is chosen for this study. It is modelled with SystemC-AMS (SCAMS) and is integrated into a SystemC-TLM (SCTLM) described digital BLE environment to achieve a global system simulation. The simulation gives results as the RF Transceiver energy consumption and Bit-Error-Rate (BER), which can be used to analyze and optimize RF system design.

솔라셀과 RF송수신기를 이용한 무선인식장치

In this paper, we newly introduce a wireless identification system using a solar cell and RF transceivers. The reader sends interrogating signal to a transponder using LED visible light, and the transponder responds to the reader using RF signal. The transponder consists of a solar cell, an amplifier, a microprocessor, and an RF transmitter. The solar cell receives the visible light from the reader and generates current to supply electric power to the other devices in the transponder. At the same time, the solar cell detects interrogating signal in the reader light. The microprocessor senses the interrogating signal and generates a responding signal. The RF transmitter radiates the responding signal to the reader. The transponder is a passive circuit because it operates without external power. In experiments, the maximum read distance between a reader and a transponder was about 1.6 meter.

Microwave front-end subsystems design for ITS/GPS applications

This paper reports the design, simulation and characterization of adaptable band pass filter, planar microstrip antenna and filtenna for GPS and ITS (intelligent transportation systems) applications. The designed microstrip slotted antenna has a 300MHz of measured bandwidth and 5.7dBi of measured gain, which is sufficient to cover the ITS band (5.85–5.925GHz). On the other hand, the developed filtenna operates in dedicated ITS band at 5.9GHz and have 1.5dBi of measured antenna gain. The reduction in filtenna gain is due to the additional insertion loss introduced by the hairpin bandpass filter incorporated in the feed of the proposed filtenna. Two adaptable bandpass filters have also been designed for GPS applications. First tunable filter operates at 1575MHz (GPS L1 frequency) while rejects 1227MHz frequency (GPS L2 frequency band). The (measured) return loss of the filter is better than 20dB from 1.5GHz to 1.6GHz; while insertion loss at 1575MHz is ∼5.5dB. Second tunable filter has been designed to cover both 1575MHz (L1 frequency band) as well as 1227MHz frequency ranges (L2 frequency band). The return loss (measured) of this filter is better than 10dB from 1.15GHz to 2.15GHz, and insertion loss is ∼5.5dB. The developed sub-systems can be used to build a low cost RF transceiver system for GPS and ITS applications.

Enerji verimli ve düşük maliyetli sensör ağlarının ISM bandı FSK alıcı vericiyle tasarlanması

Safe wireless link and long battery life are indispensable feature for a portable and outdoor used device with build-in sensors. For this purpose, duty cycling, ultra-low power electronics design, dynamic power management, wireless network architecture and medium access control concepts in the design are explained in detailed. In this work, an ultra-low power wireless sensor network is designed with 4cmx4cm size and light weight nodes sending once every three minutes 115.2 kbps 5 byte package that have up to 131.25 year battery life time in theory with 3V (2x1.5V) 1000mAh battery. 868 and 915 MHz programmable 115.2 kbps ISM band FSK RF transceiver with a low power wake-up scheme is utilized for low cost unlicensed-used wireless sensor networks designed with Back Inverted F Antennas with 100m communication range for outdoor applications and 25m for indoor applications. Sensor node requires 0.5 uA, 2.5 mA, 0.8 uA, 14.6 mA and 25mA during sleep, measurement, sniff, receive and transmit mode respectively @ 868 MHz with 3V battery. The sensors has temperature compensation feature with -40-85 °C working range.

로버스트 유무선 보안시스템을 위한 송수신 모듈의 설계

본 논문에서는 종래의 보안관리 시스템과 송수신 모듈의 단점을 개선하기 위해 유무선 복합기능의 송수신 모듈과 이를 사용한 신뢰성 높은 실시간 보안시스템을 제안한다. 제안하는 복합 송수신모듈은 RF 제어 회로와 무선 송수신 회로로 구성된다. RF제어회로는 저전력 협대역 RF 송수신 시스템으로서 마이크로프로세서의 레지스터에 저장되어 있는 특정 주파수 대역을 불러올 수 있고, 임의로 값을 쓰거나 읽어 들여 임의 주파수의 송신출력을 사용자가 제어할 수 있도록 설계한다. RF 송신 모듈의 동작을 위한 구동 알고리듬을 제시하고 설계한 복합 송수신 모듈과 동작 알고리듬을 시작품으로 구현하여 실험을 통해 유효성을 확인한다. In this paper, a design of transceiver module for real-time wire and wireless robust integrated security system to solve the problem of conventional security system and its transceiver module is proposed. The presented robust integrated security system is designed with RF control unit and wireless transceiver module. A RF controller in transceiver module works as a low-power RF transceiver system. It is designed to use specific bandwidth stored in registers and manipulate RF power of transceiver by accessing the random values of registers. Operation algorithm for RF transceiver module is also presented. The designed transceiver module and the operation algorithm are implemented and verified by experiments.

고속주파수 도약용 RF송수신기 설계 및 구현에 대한 연구

고속주파수 도약용 RF송수신기 설계 및 구현에 대한 연구