Low-power CMOS front-ends for wireless personal area networks

The potential of implementing subthreshold radio frequency circuits in deep sub-micron CMOS technology was investigated for developing low-power front-ends for wireless personal area network (WPAN) applications. It was found that the higher transconductance to bias current ratio in weak inversion could be exploited in developing low-power wireless front-ends, if circuit techniques are employed to mitigate the higher device noise in subthreshold region. The first fully integrated subthreshold low noise amplifier was demonstrated in the GHz frequency range requiring only 260 μW of power consumption. Novel subthreshold variable gain stages and down-conversion mixers were developed. A 2.4 GHz receiver, consuming 540 μW of power, was implemented using a new subthreshold mixer by replacing the conventional active low noise amplifier by a series-resonant passive network that provides both input matching and voltage amplification. The first fully monolithic subthreshold CMOS receiver was also implemented with integrated subthreshold quadrature LO (Local Oscillator) chain for 2.4 GHz WPAN applications. Subthreshold operation, passive voltage amplification, and various low-power circuit techniques such as current reuse, stacking, and differential cross coupling were combined to lower the total power consumption to 2.6 mW. Extremely compact resistive feedback CMOS low noise amplifiers were presented as a cost-effective alternative to narrow band LNAs using high-Q inductors. Techniques to improve linearity and reduce power consumption were presented. The combination of high linearity, low noise figure, high broadband gain, extremely small die area and low power consumption made the proposed LNA architecture a compelling choice for many wireless applications.Ph.D.Committee Chair: Laskar, Joy; Committee Member: Chakraborty, Sudipto; Committee Member: Chang, Jae Joon; Committee Member: Divan, Deepakraj; Committee Member: Kornegay, Kevin; Committee Member: Tentzeris, Emmanoui

Improved Wireless Security through Physical Layer Protocol Manipulation and Radio Frequency Fingerprinting

Wireless networks are particularly vulnerable to spoofing and route poisoning attacks due to the contested transmission medium. Traditional bit-layer defenses including encryption keys and MAC address control lists are vulnerable to extraction and identity spoofing, respectively. This dissertation explores three novel strategies to leverage the wireless physical layer to improve security in low-rate wireless personal area networks. The first, physical layer protocol manipulation, identifies true transceiver design within remote devices through analysis of replies in response to packets transmitted with modified physical layer headers. Results herein demonstrate a methodology that correctly differentiates among six IEEE 802.15.4 transceiver classes with greater than 99% accuracy, regardless of claimed bit-layer identity. The second strategy, radio frequency fingerprinting, accurately identifies the true source of every wireless transmission in a network, even among devices of the same design and manufacturer. Results suggest that even low-cost signal collection receivers can achieve greater than 90% authentication accuracy within a defense system based on radio frequency fingerprinting. The third strategy, based on received signal strength quantification, can be leveraged to rapidly locate suspicious transmission sources and to perform physical security audits of critical networks. Results herein reduce mean absolute percentage error of a widely-utilized distance estimation model 20% by examining signal strength measurements from real-world networks in a military hospital and a civilian hospital

A Comparison of RF-DNA Fingerprinting Using High/Low Value Receivers with ZigBee Devices

The ZigBee specification provides a niche capability, extending the IEEE 802.15.4 standard to provide a wireless mesh network solution. ZigBee-based devices require minimal power and provide a relatively long-distance, inexpensive, and secure means of networking. The technology is heavily utilized, providing energy management, ICS automation, and remote monitoring of Critical Infrastructure (CI) operations; it also supports application in military and civilian health care sectors. ZigBee networks lack security below the Network layer of the OSI model, leaving them vulnerable to open-source hacking tools that allow malicous attacks such as MAC spoofing or Denial of Service (DOS). A method known as RF-DNA Fingerprinting provides an additional level of security at the Physical (PHY) level, where the transmitted waveform of a device is examined, rather than its bit-level credentials which can be easily manipulated. RF-DNA fingerprinting allows a unique human-like signature for a device to be obtained and a subsequent decision made whether to grant access or deny entry to a secure network. Two NI receivers were used here to simultaneously collect RF emissions from six Atmel AT86RF230 transceivers. The time-domain response of each device was used to extract features and generate unique RF-DNA fingerprints. These fingeprints were used to perform Device Classification using two discrimination processes known as MDA/ML and GRLVQI. Each process (classifier) was used to examine both the Full-Dimensional (FD) and reduced dimensional feature-sets for the high-value PXIe and low-value USRP receivers. The reduced feature-sets were determined using DRA for both quantitative and qualitative subsets. Additionally, each classifier performed Device Classification using a hybrid interleaved set of fingerprints from both receivers

IEEE 802.15.4-PHY Packet Detection and Transmission System With Differential Encoding For Low Power IoT Networks

Synchronization is the first operation in a digital base band receiver. The accuracy of the synchronizer shapes up the performance of the base band receiver. Synchronization is broadly divided into Carrier Frequency and Phase Synchronization, Symbol Timing and Frame Synchronization. If number of false detections in frame synchronization are high then large amount of power is wasted for processing unwanted packets. In this paper, we are proposing a packet detection and transmission system with differential encoding for low power IoT networks which reduces the number of false packet detections compared to existing preamble detection techniques. The proposed frame synchronization method decides packet is valid or not by cross correlating received packet with fixed preamble sequence and determine its boundaries. The proposed system is analyzed with smart metering power data and corresponding probabilities of packet missing and false detection, power consumption and bit error rate are analyzed. At 3 dB SNR the number of false detections are reduced by 170 compared to conventional correlation method thereby saving 15.8 % of processing power at receiver

Design of zigbee transceiver for IEEE 802.15.4 using matlab/simulink

ZigBee technology was developed for a wireless personal area networks (PAN), aimed at control and military applications with low data rate and low power consumption. This thesis is mainly focusing on development of Matlab/Simulink model for ZigBee transceiver at physical layer using IEEE 802.15.4. ZigBee is a low-cost, low-power, wireless mesh networking standard. First, the low cost allows the technology to be widely deployed in wireless control and monitoring applications. Second, the low power-usage allows longer life with smaller batteries. Third, the mesh networking provides high reliability and more extensive range. The work presented here is to show how we can implement ZigBee transceiver with its specifications by using Matlab/simulink, without using complex mathematical blocks. A ZigBee chip can tested and prepared by shifting the whole work from matlab environment to cadance environment. This can be done by HDL languages like Verilog HDL. Here, Minimum Shift Keying (MSK) modulation technique is described, an analysis of which shows that the theoretical maximum bandwidth efficiency of MSK is 2 bits/s/Hz which is same as for Quadrature Phase Shift Keying (QPSK) and Offset Quadrature Phase Shift Keying (Offset QPSK). The implementation clearly confirms the viability of theoritical approach. Results show that OQPSK modulation with half sine pulse shaping is perfectly employed ZigBee technology

Modular Home Automation Systems for Senior Citizens

The aging of the population is one of the biggest challenges in our society. Citizens life expectancy is growing and the birth rate is decreasing. In long-term this is untenable. Thanks to the advance of technology we can try to help to reduce the impact of this problem. I introduce a brief work on Modular Home Automation Systems with energy efficiency adapted to nowadays lifestyle and technology. These systems make use of wireless communications instead of wired ones to minimize the invasion of new devices. Because of the characteristics of these systems, ZigBee suits perfectly. ZigBee is a specification made to provide low rate wireless communications. ZigBee networks make the communication more efficient and adaptive. To achieve a modular environment, we use some design patterns from Software Engineering ,which also improve the security and maintainability of the system. The system is also expandable and reliable among other capabilities

Ultrasound Indoor Positioning System Based on a Low-Power Wireless Sensor Network Providing Sub-Centimeter Accuracy

This paper describes the TELIAMADE system, a new indoor positioning system based on time-of-flight (TOF) of ultrasonic signal to estimate the distance between a receiver node and a transmitter node. TELIAMADE system consists of a set of wireless nodes equipped with a radio module for communication and a module for the transmission and reception of ultrasound. The access to the ultrasonic channel is managed by applying a synchronization algorithm based on a time-division multiplexing (TDMA) scheme. The ultrasonic signal is transmitted using a carrier frequency of 40 kHz and the TOF measurement is estimated by applying a quadrature detector to the signal obtained at the A/D converter output. Low sampling frequencies of 17.78 kHz or even 12.31 kHz are possible using quadrature sampling in order to optimize memory requirements and to reduce the computational cost in signal processing. The distance is calculated from the TOF taking into account the speed of sound. An excellent accuracy in the estimation of the TOF is achieved using parabolic interpolation to detect of maximum of the signal envelope at the matched filter output. The signal phase information is also used for enhancing the TOF measurement accuracy. Experimental results show a root mean square error (rmse) less than 2 mm and a standard deviation less than 0.3 mm for pseudorange measurements in the range of distances between 2 and 6 m. The system location accuracy is also evaluated by applying multilateration. A sub-centimeter location accuracy is achieved with an average rmse of 9.6 mm.Junta de Andalucía P08-TIC-0388

When the Industry Goes Wireless: Drivers, Requirements, Technology and Future Trends

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Wireless industrial monitoring and control networks: the journey so far and the road ahead

While traditional wired communication technologies have played a crucial role in industrial monitoring and control networks over the past few decades, they are increasingly proving to be inadequate to meet the highly dynamic and stringent demands of today’s industrial applications, primarily due to the very rigid nature of wired infrastructures. Wireless technology, however, through its increased pervasiveness, has the potential to revolutionize the industry, not only by mitigating the problems faced by wired solutions, but also by introducing a completely new class of applications. While present day wireless technologies made some preliminary inroads in the monitoring domain, they still have severe limitations especially when real-time, reliable distributed control operations are concerned. This article provides the reader with an overview of existing wireless technologies commonly used in the monitoring and control industry. It highlights the pros and cons of each technology and assesses the degree to which each technology is able to meet the stringent demands of industrial monitoring and control networks. Additionally, it summarizes mechanisms proposed by academia, especially serving critical applications by addressing the real-time and reliability requirements of industrial process automation. The article also describes certain key research problems from the physical layer communication for sensor networks and the wireless networking perspective that have yet to be addressed to allow the successful use of wireless technologies in industrial monitoring and control networks