Wireless RF Research Articles

Radio Frequency EMF Exposure due to Gsm Mobile Phones Base Stations: Measurements and Analysis in Nigerian Environment

For some time now, members of the public have been concerned about the possible feared health impacts and safety of new RF technologies, including radar, radio and television broadcasting facilities, microwave ovens, point-to-point microwave radio, and satellite communications systems. The most recent concern is the safety of mobile phones and their base stations (BSs). In Nigerian some people believed that exposure to radiation from BSs for long period could cause different diseases like cancer, destroys reproductive organs, congenital anomalies, epilepsy and persistent headache and some of the BSs were installed near the home of residence. Owing to the growing concern, this study was conducted to evaluate the radio frequency radiation levels near several mobile phone BSs in GRA, Benin City, Nigeria. Measurements in terms of power density were made to check the exposure level at public locations. The data (power density) were collected from three (3) major GSMoperators BSs in Nigeria; all the BSs were located in GRA, Benin City, Nigeria. For each of these BSs the measurements were taken at 5m intervals to 100m from the BSs. From the results, the maximum of power density obtained for GLo, MTN and Airtel are 1.62mW/m 2 , 3.04mW/m 2 and 1.52mW/m 2 respectively. These values are quite small compared to international standard limits like those adopted by the International Commission on Non-ionizing Radiation Protection (ICNIRP) which is 9mW/m 2 for the public and 22.5mW/m 2 for those professionals involved in telecommunication industry. http://dx.doi.org/10.4314/njt.v34i4.20

Broadcast-Enabled Massive Multicore Architectures: A Wireless RF Approach

Broadcast traditionally has been regarded as a prohibitive communication transaction in multiprocessor environments. Nowadays, such a constraint largely drives the design of architectures and algorithms all-pervasive in diverse computing domains, directly and indirectly leading to diminishing performance returns as the many-core era is approaching. Novel interconnect technologies could help revert this trend by offering, among others, improved broadcast support, even in large-scale chip multiprocessors. This article outlines the prospects of wireless on-chip communication technologies pointing toward low-latency (a few cycles) and energy-efficient broadcast (a few picojoules per bit). It also discusses the challenges and potential impact of adopting these technologies as key enablers of unconventional hardware architectures and algorithmic approaches, in the pathway of significantly improving the performance, energy efficiency, scalability, and programmability of many-core chips.

Case Study: Hand Gesture Based Digital Pen

In this paper an MEMS accelerometer mostly based on gesture recognition algorithm and its application are presented. The hardware module consists of a triaxial MEMS accelerometer, microcontroller, and RF wireless transmission module for sensing and collecting accelerations of handwriting and hand gesture trajectories. Users will use this digital pen to write down digits, alphabets& some hand gestures. The accelerations of hand motions deliberate by the accelerometer are transmit wirelessly to a personal computer for trajectory recognition. The trajectory algorithm collected of information variety assortment, signal pre-processing for reconstruct the trajectory to satisfy the collective errors caused by drift of sensors. So, by altering the location of MEMS (micro electro mechanical systems) we can proficient to demonstrate the alphabetical characters and numerical on PC.

A High-Speed Camera-Based Approach to Massive Sound Sensing With Optical Wireless Acoustic Sensors

This paper introduces an optical wireless audio system, which takes advantage of the parallel transmission feature offered by the arrangement of LEDs and a high-speed video camera. The motivation for building such system is the limitation encountered when deploying huge arrays of sound sensors, as existent wired and RF wireless microphones are undermined by complexity, energy, and bandwidth issues. In contrast, the proposed prototype is able to simultaneously capture 120 audio channels with full bandwidth each. Although the scalability to more channels is currently constrained by the camera interface hardware, our numerical analysis suggests that the proposed algorithms can decode optical signals of over 12 500 audio channels in a single GPU card. We discuss the various challenges involved in its deployment from the optical, image, and audio signal processing standpoints, and develop theoretical and practical solutions to accomplish a full real-time system integration. We further present examples of typical applications such as acoustic imaging of sound fields by beamforming with microphone arrays.

Software Defined Electronics: A Revolutionary Change in Design and Teaching Paradigm of RF Radio Communications Systems

Abstract Band-pass signals are used everywhere in radio communications. The band-pass property makes the substitution of each RF/microwave/ optical analog signal processing possible with a low-frequency digital one in Software Defined Electronics (SDE). In SDE, the high frequency band-pass signals are transformed into the BaseBand (BB) by a universal HW device and every application is implemented in BB, entirely in software. SDE concept uses (i) the lowest sampling rate attainable theoretically and (ii) the same universal HW device in every application. The huge level of flexibility offered by the SW implementation is essential in many applications from cognitive radio to adaptive reconfigurable systems. This tutorial, written for interested readers who have no solid background in software defined radio, virtual instrumentation and SoC technology, surveys the SDE theory, uses a step-by-step approach for the derivation of BB equivalents and demonstrates the application of SDE concept in scientific research, prototyping and education.

A matched RF charger for wireless RF power harvesting system

ABSTRACTIn this article, special type of RF Charger is proposed for Wireless RF power harvesting system. RF charger is consisted of impedance matching circuit, full bridge CMOS rectifier, active diode, hysteresis switch, and DC–DC booster. The proposed RF charger is to obtain maximum available RF power through adjusting impedance matching circuitries. The proposed RF charger is matched to Korean WCDMA frequency band from 1960 to 1980 MHz. The minimum input RF power for charging 5 V battery is −10 dBm. The RF to DC conversion efficiency of the RF charger is 81% at 30 mA load current with 5 V battery, and the maximum output voltage is 5.5 V. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1622–1625, 2015

Self-similar design for stretchable wireless LC strain sensors

Stretchable sensors provide a foundation for applications that exceed the scope of conventional device technologies due to their unique capacity to integrate with soft materials and curvilinear surfaces. This article presents the implementation and characterization of a large-area stretchable wireless RF strain sensor, operating at around 760MHz, based on the concept of self-similar design. It has an electrical LC resonant circuit formed by a self-similar inductor coil and a capacitor to facilitate passive wireless sensor. The inductance of the wireless sensor varies with the elongation of the PDMS substrate, so is the resonance frequency of the sensor that is detected using an external coil linked to a vector network analyzer. Finite element modeling was used in combination with experimental verification to demonstrate that the wireless strain sensor with 300μm width can be stretched up to 40%. Self-similar structured coil incorporating variable inductance has been implemented to monitor the strain of artificial skin. Strain response of the stretchable wireless sensor has been characterized by experiments, and demonstrates high strain responsivity about 33.7MHz/10%, which confirms the feasibility of strain sensing for biomedical and wearable applications.

Software-Defined-Radio-Based Wireless Tomography: Experimental Demonstration and Verification

This letter presents an experimental demonstration of software-defined-radio-based wireless tomography using computer-hosted radio devices called Universal Software Radio Peripheral (USRP). This experimental brief follows our vision and previous theoretical study of wireless tomography that combines wireless communication and RF tomography to provide a novel approach to remote sensing. Automatic data acquisition is performed inside an RF anechoic chamber. Semidefinite relaxation is used for phase retrieval, and the Born iterative method is utilized for imaging the target. Experimental results are presented, validating our vision of wireless tomography.

基于315 Mhz无线射频技术的全向遥控小夜灯

21世纪的人口老龄化浪潮已经成为了全球发展的趋势。自从2000年以来，我国逐渐步入了老龄化国家行列。老年人的健康问题、老年人人口数量的发展趋势等问题，现在已经受到很大的重视。老年人由于身体机能下降，夜间起夜、吃药、喝水等活动的频率增加，在黑暗中发生摔倒和撞伤的几率也增大。尤其对于独居老人，夜间发生意外伤害不易得到救助。本文针对老年人夜间活动不便设计了一种小夜灯，采用无线射频遥控技术，可以远程对小夜灯开关进行控制，且无需对准灯头，减少老年人夜间寻找灯泡开关的不便。按键设计简单大方，便于老年人夜间轻松稳定地按下。采用LED灯头和电路结构、亮度的优化设计，控制小夜灯成本，降低功耗和节约电能，解决部分老年人对于用经济成本方面的顾虑。 Aged tendency of population has become a worldwide trend in 21th century. Since the year of 2000, our country has gradually stepped into ageing country camp. Health issue, population development tendency of the aged has been attached more importance. As somatic function of the aged drops, the frequency of the aged getting up at night to wash, medicine, drink increases, the odds of falling and crushing in the darkness also increases. Especially for the aged who live alone, if accident happens at night, they will not get help easily. This paper designed a night-light aiming at reducing the aged inconvenience during their night activities. The night-light adopts wireless RF remote control technique, and the old can control night-light on and off remotely without remote aiming at the night-light, reducing the inconvenience of finding light switch at night. The key is designed simply and apparently, easy to press stably at night for the aged. LED lamp cap is ado- pted and circuit configuration and lamp luminance are optimized to control the night-light’s cost, reduce power dissipation and save electricity, which solve the scruple of economic issue of some aged people.

Fundamentals of Modern RF Wireless Receivers: A Short Tutorial

i»?To be compliant with multistandard applications, the RF front end of a modern transceiver must satisfy several challenging tasks such as large operative bandwidth, low noise, and high linearity. Over the years, addressing such requirements has significantly changed the radio architecture toward an ultimate solution based on current mode signal processing and passive mixers. In this article, after a brief description of the typical structure of a wireless receiver, voltage and current mode signal processing will be compared showing why a fully current-mode approach is more suitable in deep-scaled CMOS technologies [1], [2].

Inductively coupled wireless RF coil arrays

As the number of coils increases in multi-channel MRI receiver-coil arrays, RF cables and connectors become increasingly bulky and heavy, degrading patient comfort and slowing workflow. Inductive coupling of signals provides an attractive “wireless” approach, with the potential to reduce coil weight and cost while simplifying patient setup. In this work, multi-channel inductively coupled anterior arrays were developed and characterized for 1.5T imaging. These comprised MR receiver coils inductively (or “wirelessly”) linked to secondary or “sniffer” coils whose outputs were transmitted via preamps to the MR system cabinet. The induced currents in the imaging coils were blocked by passive diode circuits during RF transmit. The imaging arrays were totally passive, obviating the need to deliver power to the coils, and providing lightweight, untethered signal reception with easily positioned coils. Single-shot fast spin echo images were acquired from 5 volunteers using a 7-element inductively coupled coil array and a conventionally cabled 7-element coil array of identical geometry, with the inductively-coupled array showing a relative signal-to-noise ratio of 0.86 +/− 0.07. The concept was extended to a larger 9-element coil array to demonstrate the effect of coil element size on signal transfer and RF-transmit blocking.

Channel Assignment Algorithm in Centralized WLAN

To reduce the number of inter-disturb access points and the interference among access points in same channel, with research on interference issus and channel assignment algorithms of wireless local area network, a scheme suitable for centralized wireless local area network was proposed aiming to minimize the total interference among access points, which comprehensively considerate the number of neighbor and the received power. And then the algorithm with cases was simulated and analyzed, the result of NS2 simulation indicated that the algorithm was simple, effective and feasible, which could realize dynamic adjustment to the wireless LAN RF channel and had a better load balance effect among non-overlapping channels.

Study on Facilities Agriculture Remote Monitor and Control System Based on Tri-Networks Convergence

Facility agriculture environment monitoring system of the existing main adopts the wired communication technology, such as serial bus technology and field bus technology for communication. This system has the advantages of good interoperability, strong anti-interference ability, but the poor stability, low reliability, difficult to deploy, installation and maintenance costs high, which greatly limits its application in the design of facilities agriculture field. Three nets fusion refers to the 3G, RFID and Internet combination. In this paper, the 3G network, wireless radio frequency technology and Internet technology combining, in order to solve the above problems, the use of 3G network and the Internet to a large amount of data real-time remote transmission, using radio frequency network RFID technology through the short distance wireless data transmission terminal sensors to collect information, these information in time through the3G network and the Internet are transmitted to the the remote controller. The remote controller sends according to terminal sensor control information, through the 3G network and the Internet will control information is transmitted to the radio frequency network, wireless RF network through wireless communication control information is transmitted to the terminal controller, the final completion of the remote monitoring and control of agricultural facilities. The experimental results show that, the system can meet the real-time and can perform remote transmission for large data, provide the technical basis of visual audio data monitoring information transmission for agricultural facilities.

On-Wafer Calibration Technique for High Frequency Measurement with Simultaneous Voltage and Current Tuning

This paper presents a novel on wafer calibration method for the measurement of radio RF passive components with R&S vector network analyzer (VNA) at RF and mm-wave frequency. This method has employed the high frequency structure simulator (HFSS) results along with multi-level optimizations to get the nominal values used for on wafer calibration. Multiline (Thru-reflect-line) TRL calibration standards fabricated on the same substrate are used with better accuracy. Measured results show that a thru line provides less than 0.015 dB insertion loss throughout the frequency range of 1GHz-67GHz. This result is much better compared to the results achieved by conventional Short-open-load-thru (SOLT) calibration and (Thru-reflect-line) TRL calibration using the available calibration substrates. Using this calibration technique, the phase variation of the thru line shows less than 3° at 67GHz which is much lower than 15° achieved by the conventional calibration methods. The measurement of the multi band characteristics of the RF passive components by simultaneous current and voltage application has also been demonstrated successfully.

FireFly

Conventional static datacenter (DC) network designs offer extreme cost vs. performance tradeoffs---simple leaf-spine networks are cost-effective but oversubscribed, while "fat tree"-like solutions offer good worst-case performance but are expensive. Recent results make a promising case for augmenting an oversubscribed network with reconfigurable inter-rack wireless or optical links. Inspired by the promise of reconfigurability, this paper presents FireFly, an inter-rack network solution that pushes DC network design to the extreme on three key fronts: (1) all links are reconfigurable; (2) all links are wireless; and (3) non top-of-rack switches are eliminated altogether. This vision, if realized, can offer significant benefits in terms of increased flexibility, reduced equipment cost, and minimal cabling complexity. In order to achieve this vision, we need to look beyond traditional RF wireless solutions due to their interference footprint which limits range and data rates. Thus, we make the case for using free-space optics (FSO). We demonstrate the viability of this architecture by (a) building a proof-of-concept prototype of a steerable small form factor FSO device using commodity components and (b) developing practical heuristics to address algorithmic and system-level challenges in network design and management.

A Temperature and Humidity Monitoring System of Grain Depot Based on WSN

The traditional temperature and humidity monitoring system of grain depot used to realize in wired network which needs to deploy a large number of cables. The maintainability and scalability is poor. We present a solution of monitoring temperature and humidity of grain depot based on wireless sensor network (WSN). The temperature and humidity data acquisition and control node is composed of digital temperature and humidity sensor and RF wireless chip and the main control chip. Based on the Zigbee technology, these nodes construct a WSN in Ad Hoc in order to collect, monitor and control the temperature and humidity in the monitoring area. The convergence node in the WSN will packed acquisition data from other nodes and then transmit them to a remote monitoring host through the GPRS wireless mobile network. By means of the statistical analysis of the real-time data collected, the monitoring host can alarm and feedback control the temperature and humidity of grain depot. The experimental results show that the system has strong scalability, low power consumption and high efficiency.

The Design of Communication System for Wearable Health Monitoring Equipment

Viewing the health care problem facing the aging society, an intelligent wearable monitoring system is designed, which is able to collecting real-time data and analyze the data for physiological parameters for a plurality of monitoring object. The system, with CAN bus interface chip C8051F040 low power and wireless RF chip nRF24L01 as the core, collect real-time multiple physiological parameters of monitored objects through wireless mode, and send the data to the monitoring center through high reliability CAN bus mode, so as to achieve the intelligent home health care function.

The Development of Underground Personnel Data Terminal Based on RSSI Location

Based on the emerging ZigBee wireless RF communication technology, this paper presents the design of a miner information collection terminal. The entire system is designed around the CC2431 SoC hardware circuit, through ZigBee networking, to achieve the location of underground environment and miner vital signs data acquisition, so that it can provide effective help to quickly carry out rescue work.

A Security System Design of WSN Based on Nodes Identification

This paper introduces the design and implementation of the safe transmission mechanism of wireless sensor network. This scheme is aimed at reducing node’s cost of computing and communication. Firstly, the WSN will be clustered. Then, encryption key will be generated in the clusters, which is used of data encryption and decryption based on nodes identification to ensure data security. The system uses the wireless microcontroller CC2430/CC2431 to perform the simulation testing for program modules of Chipcon, which integrates CC2420RF wireless RF transceiver. Experimental results show that the new algorithm can increase traffic, node utilization and improve the confidentiality and security of sensor information.

Study and Capacity Evaluation of SISO, MISO and MIMO RF Wireless Communication Systems

The wireless communication systems has gone from different generations from SISO systems to MIMO systems. Bandwidth is one important constraint in wireless communication. In wireless communication, high data transmission rates are essential for the services like tripple play i.e. data, voice and video. At user end the capacity determines the quality of the communication systems. This paper aims to compare the different RF wireless communication systems like SISO, MISO, SIMO and MIMO systems on the capacity basis and explaining the concept as today, the wireless communication has evolved from 2G, 3G to 4G and the companies are fighting to create networks with more and more capacity so that data rates can be increased and customers can be benefitted more. The ultimate goal of wireless communication systems is to create a global personal and multimedia communication without any capacity issues. Key Terms MIMO, SISO, SIMO, MISO Capacity