Wisent: Robust Downstream Communication and Storage for Computational RFIDs

Computational RFID (CRFID) devices are emerging platforms that can enable perennial computation and sensing by eliminating the need for batteries. Although much research has been devoted to improving upstream (CRFID to RFID reader) communication rates, the opposite direction has so far been neglected, presumably due to the difficulty of guaranteeing fast and error-free transfer amidst frequent power interruptions of CRFID. With growing interest in the market where CRFIDs are forever-embedded in many structures, it is necessary for this void to be filled. Therefore, we propose Wisent-a robust downstream communication protocol for CRFIDs that operates on top of the legacy UHF RFID communication protocol: EPC C1G2. The novelty of Wisent is its ability to adaptively change the frame length sent by the reader, based on the length throttling mechanism, to minimize the transfer times at varying channel conditions. We present an implementation of Wisent for the WISP 5 and an off-the-shelf RFID reader. Our experiments show that Wisent allows transfer up to 16 times faster than a baseline, non-adaptive shortest frame case, i.e. single word length, at sub-meter distance. As a case study, we show how Wisent enables wireless CRFID reprogramming, demonstrating the world's first wirelessly reprogrammable (software defined) CRFID.Comment: Accepted for Publication to IEEE INFOCOM 201

Transiently Powered Computers

Demand for compact, easily deployable, energy-efficient computers has driven the development of general-purpose transiently powered computers (TPCs) that lack both batteries and wired power, operating exclusively on energy harvested from their surroundings. TPCs\u27 dependence solely on transient, harvested power offers several important design-time benefits. For example, omitting batteries saves board space and weight while obviating the need to make devices physically accessible for maintenance. However, transient power may provide an unpredictable supply of energy that makes operation difficult. A predictable energy supply is a key abstraction underlying most electronic designs. TPCs discard this abstraction in favor of opportunistic computation that takes advantage of available resources. A crucial question is how should a software-controlled computing device operate if it depends completely on external entities for power and other resources? The question poses challenges for computation, communication, storage, and other aspects of TPC design. The main idea of this work is that software techniques can make energy harvesting a practicable form of power supply for electronic devices. Its overarching goal is to facilitate the design and operation of usable TPCs. This thesis poses a set of challenges that are fundamental to TPCs, then pairs these challenges with approaches that use software techniques to address them. To address the challenge of computing steadily on harvested power, it describes Mementos, an energy-aware state-checkpointing system for TPCs. To address the dependence of opportunistic RF-harvesting TPCs on potentially untrustworthy RFID readers, it describes CCCP, a protocol and system for safely outsourcing data storage to RFID readers that may attempt to tamper with data. Additionally, it describes a simulator that facilitates experimentation with the TPC model, and a prototype computational RFID that implements the TPC model. To show that TPCs can improve existing electronic devices, this thesis describes applications of TPCs to implantable medical devices (IMDs), a challenging design space in which some battery-constrained devices completely lack protection against radio-based attacks. TPCs can provide security and privacy benefits to IMDs by, for instance, cryptographically authenticating other devices that want to communicate with the IMD before allowing the IMD to use any of its battery power. This thesis describes a simplified IMD that lacks its own radio, saving precious battery energy and therefore size. The simplified IMD instead depends on an RFID-scale TPC for all of its communication functions. TPCs are a natural area of exploration for future electronic design, given the parallel trends of energy harvesting and miniaturization. This work aims to establish and evaluate basic principles by which TPCs can operate

Leveraging Backscatter for Ultra-low Power Wireless Sensing Systems

The past few years have seen a dramatic growth in wireless sensing systems, with millions of wirelessly connected sensors becoming first-class citizens of the Internet. The number of wireless sensing devices is expected to surpass 6.75 billion by 2017, more than the world\u27s population as well as the combined market of smartphones, tablets, and PCs. However, its growth faces two pressing challenges: battery energy density and wireless radio power consumption. Battery energy density looms as a fundamental limiting factor due to slow improvements over the past several decades (3x over 22 years). Wireless radio power consumption is another key challenge because high-speed wireless communication is often far more expensive energy-wise than computation, storage and sensing. To make matters worse, wireless sensing devices are generating an increasing amount of data. These challenges raise a fundamental question --- how should we power and communicate with wireless sensing devices. More specifically, instead of using batteries, can we leverage other energy sources to reduce, if not eliminate, the dependence on batteries? Similarly, instead of optimizing existing wireless radios, can we fundamentally change how radios transmit wireless signals to achieve lower power consumption? A promising technique to address these questions is backscatter --- a primitive that enables RF energy harvesting and ultra-low-power wireless communication. Backscatter has the potential to reduce dependence on batteries because it can obtain energy by rectifying the wireless signals transmitted by a backscatter reader. Backscatter can also work by reflecting existing wireless signals (WiFi, BLE) when these are available nearby. Because signal reflection only consumes uWs of power, backscatter can enable ultra-low-power wireless communication. However, the use of backscatter for communicating with wireless sensing devices presents several challenges. First, decreasing RF power across distance limits the operational range of micro-powered backscatter devices. This raises the question of how to maintain a communication link with a backscatter device despite tiny amount of harvested power. Second, even though the backscatter RF front-end is extremely power-efficient, the computational and sensing overhead on backscatter sensors limit its ability to operate with a few micro-Watts of power. Such overhead is a negligible factor of overall power consumption for platforms where radio power consumption is high (e.g. WiFi or Bluetooth based devices). However, it becomes the bottleneck for backscatter based platforms. Third, backscatter readers are not currently deployed in existing indoor environments to provide a continuous carrier for carrying backscattered information. As a result, backscatter deployment is not yet widespread. This thesis addresses these challenges by making the following contributions. First, we design a network stack that enables continuous operation despite decreasing harvested power across distance by employing an OS abstraction --- task fragmentation. We show that such a network stack enables packet transfer even when the whole system is powered by a 3cmx3cm solar panel under natural indoor light condition. Second, we design a hardware architecture that minimizes the computational overhead of backscatter to enable over 1Mbps backscatter transmission while consuming less than 100uWs of power, a two order of magnitude improvement over the state-of-the-art. Finally, we design a system that can leverage both ambient WiFi and BLE signals for backscatter. Our empirical evaluation shows that we can backscatter 500bps data on top of a WiFi stream and 50kbps data on top of a Bluetooth stream when the backscatter device is 3m away from the commercial WiFi and Bluetooth receivers

Efficient and Low-Cost RFID Authentication Schemes

Security in passive resource-constrained Radio Frequency Identification (RFID) tags is of much interest nowadays. Resistance against illegal tracking, cloning, timing, and replay attacks are necessary for a secure RFID authentication scheme. Reader authentication is also necessary to thwart any illegal attempt to read the tags. With an objective to design a secure and low-cost RFID authentication protocol, Gene Tsudik proposed a timestamp-based protocol using symmetric keys, named YA-TRAP*. Although YA-TRAP* achieves its target security properties, it is susceptible to timing attacks, where the timestamp to be sent by the reader to the tag can be freely selected by an adversary. Moreover, in YA-TRAP*, reader authentication is not provided, and a tag can become inoperative after exceeding its pre-stored threshold timestamp value. In this paper, we propose two mutual RFID authentication protocols that aim to improve YA-TRAP* by preventing timing attack, and by providing reader authentication. Also, a tag is allowed to refresh its pre-stored threshold value in our protocols, so that it does not become inoperative after exceeding the threshold. Our protocols also achieve other security properties like forward security, resistance against cloning, replay, and tracking attacks. Moreover, the computation and communication costs are kept as low as possible for the tags. It is important to keep the communication cost as low as possible when many tags are authenticated in batch-mode. By introducing aggregate function for the reader-to-server communication, the communication cost is reduced. We also discuss different possible applications of our protocols. Our protocols thus capture more security properties and more efficiency than YA-TRAP*. Finally, we show that our protocols can be implemented using the current standard low-cost RFID infrastructures.Comment: 21 pages, Journal of Wireless Mobile Networks, Ubiquitous Computing, and Dependable Applications (JoWUA), Vol 2, No 3, pp. 4-25, 201

Low Redshift Baryon Acoustic Oscillation Measurement from the Reconstructed 6-degree Field Galaxy Survey

Low redshift measurements of Baryon Acoustic Oscillations (BAO) test the late time evolution of the Universe and are a vital probe of Dark Energy. Over the past decade both the 6-degree Field Galaxy Survey (6dFGS) and Sloan Digital Sky Survey (SDSS) have provided important distance constraints at $z < 0.3$. In this paper we re-evaluate the cosmological information from the BAO detection in 6dFGS making use of HOD populated COLA mocks for a robust covariance matrix and taking advantage of the now commonly implemented technique of density field reconstruction. For the 6dFGS data, we find consistency with the previous analysis, and obtain an isotropic volume averaged distance measurement of $D_{V}(z_{\mathrm{eff}}=0.097) = 372\pm17(r_{s}/r_{s}^{\mathrm{fid}})\,\mathrm{Mpc}$, which has a non-Gaussian likelihood outside the $1\sigma$ region. We combine our measurement from both the post-reconstruction clustering of 6dFGS and SDSS MGS offering the most robust constraint to date in this redshift regime, $D_{V}(z_{\mathrm{eff}}=0.122)=539\pm17(r_{s}/r^{\mathrm{fid}}_{s})\,\mathrm{Mpc}$. These measurements are consistent with standard $\Lambda\mathrm{CDM}$ and after fixing the standard ruler using a Planck prior on $\Omega_{m}h^{2}$, the joint analysis gives $H_{0}=64.0\pm3.5\,\mathrm{kms}^{-1}\mathrm{Mpc}^{-1}$. In the near future both the Taipan Galaxy Survey and the Dark Energy Spectroscopic Instrument (DESI) will improve this measurement to $1\%$ at low redshift.Comment: 13 pages, 12 figure

Ethical implication of emerging technologies

Titre de l'écran-titre (visionné le 3 mai 2007

On body performance evaluation of passive RFID antennas inside bandage

Radio Frequency Identification (RFID) permits us to remotely exchange information utilizing electromagnetic waves in order to distinguish and track RFID tags by RFID readers. Usually RFID tags contain some code, which is employed for identification purpose. Utilization of RFID's for the detection of objects is becoming more common every day. On the other hand, the field of examining environmental parameters utilizing RFID antennas apparatuses is also evolving number of the environmental parameters are analyzed nowadays utilizing RFID tags, beginning with the identification of a modification of the electric field inside chamber due to change in pressure, to the analysis of change in the body temperature. In this thesis, development and measurement of RFID tags for the measurement of humidity inside bandage are performed. The basic idea of this measurement is to help the doctors in determining the condition of injury inside bandage, as most visible sign for the doctors to determine the condition of injury is humidness inside the bandage. Usually doctors open bandage to check whether the injury is in good condition or not. Detecting humidity level inside the bandage using RFIDs can help doctors to know status of injury without opening bandage, as opening bandage costs time and effort, also opening in unhealthy conditions can cause infection to the injury. Three different kinds of passive RFID tags are used to analyze the performance inside the bandage. One commercial RFID tag known as Dogbone designed by Smartrac is used. This antenna is to measure the humidity level in the industrial environments including construction material, health care, and automotive production units. Dogbone is a UHF RFID antenna, which employs RF Micron IC, innovative product that automatically adjust the input impedance in order to accumulate the changes in the external environment and present results in the digitized output. Although Smartrac´s Dogbone antenna is specially designed for humidity measurement, but because of its high sensitive antenna and weak insulation from the body, its performance dwindles greatly because of body and the bandage. Later on utilizing the brush painting fabrication method for antennas, two type of RFID tags are developed on paper and bandage. Paper utilized for silver brush painting is common A4 paper available for printing purposes while the bandage is made up of Rayon, which is stretchable and commonly used in the first aid kits. Developed antennas are sintered for 15 minutes and 125-degree centigrade, after which their performance is analyzed. Best RFID tags, among all fabricated RFID tags are chosen to do the measurement. Effects of body, bandage and humidity on the performance of RFID tag on paper and bandage RFID tags are analyzed. Smartrac ”Dogbone” and self-designed RFID tags on paper and bandage lose their performance by coming closer to the body, tags loose more performance when they are closer to the inner side of the arm and they are almost least affected by the outer side of arm. Increase in humidity also reduces performance of RFID tags, but interesting phenomenon observed is the effect by the number of turns of the bandage around the RFID tag on the body. The performance of RFID tag fabricated on paper and provided by Smartrac dwindles by increasing turns of the bandage but it’s interesting to note that the tag developed on bandage is almost unaffected by a number of turns of the bandage. Effect of bandage on the RFID tag fabricated on bandage is quite unique, this phenomenon can be utilized in different fields as measurement results show that RFID tag created using same material provide almost same kind of performance under pack-aging of same material but this need further studies to get affirmation

Design of Systems and Optimizations for Autonomous Agents using passive RFID Localization Techniques - Recycling Collaborative Robots

This paper aims to describe the work done towards designing and implementing systems and optimizations for a set of autonomous robots that intend to collaborate towards accomplishing the specific common goal of transporting recycled objects. At first the paper dives into the aspects of autonomous behavior and describes what exactly constitutes autonomous behavior and then proceeds to explain the specifics of the research work in our lab at Georgia Tech and also mentions the importance and reasons behind performing such research. The paper then goes into an extensive literature review of autonomous collaborative topics and puts emphasis on RFID localization techniques. And finally describes the results and discusses the outcomes of the project. Having the research abruptly paused due to the COVID-19 pandemic in Spring of 2020, prevented us from getting to implement the collaborative medium for the robots and putting into a software service box for shipment, however we were able to discover many new findings in the fields of autonomous behavior development and implement a successful and consistent RFID reader-tag duo for our robots to be next used in implementing a collaborative medium for the robots. Special thanks and gratitude towards professors, advisors, UROP representatives and instructors, and graduate students who helped me and our research group in conducting this great research.Undergraduat