M. Potkonjak

University of California, Los Angeles, Los Ángeles, California, United States

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Publications (133)54.52 Total impact

  • V. Goudar · M. Potkonjak
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    ABSTRACT: Remote health monitoring BASNs promise substantive improvements in the quality of healthcare by providing access to diagnostically rich patient data in real-time. However, adoption is hindered by the threat of compromise of the diagnostic quality of the data by faults. Simultaneously, unresolved issues exist with the secure sharing of the sensitive medical data measured by automated BASNs, stemming from the need to provide the data owner (BASN user / patient) and the data consumers (healthcare providers, insurance companies, medical research facilities) secure control over the medical data as it is shared. We address these issues with a robust watermarking approach constrained to leave primary data semantic metrics unaffected and secondary metrics affected minimally. Further, the approach is coordinated with a fault tolerant sensor partitioning technique to afford high semantic accuracy together with recovery of bio signal semantics in the presence of sensor faults, while preserving the robustness of the watermark so that it is not easily corrupted, recovered or spoofed by malicious data consumers. Based on experimentally collected datasets from a gait-stability monitoring BASN, we show that our watermarking technique can robustly and effectively embed up to 1000 bit watermarks under these constraints.
    No preview · Article · Mar 2015
  • Vishwa Goudar · Miodrag Potkonjak
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    ABSTRACT: One of the most important infrastructure requirements in the domain of remote health monitoring BASNs is the secure collection and dissemination of the user's medical data. Data security desiderata in this application domain are not limited to ensuring the confidentiality and integrity of medical data that has been logged to a data sink. Requirements also arise from the need to provide the data owner (BAN user / patient) and the data consumers (healthcare providers, insurance companies, medical research facilities) secure control over the data as it is shared between these various stakeholders. Here, we study a robust watermarking technique to embed security information into biosignal data such that the semantic fidelity of the data is unaffected, while simultaneously ensuring that the watermark is not easily erased or corrupted by malicious data consumers. In doing so, we address three use-cases: proof of ownership, wherein the data owner can prove that she/he is the originator of the data; data tracking, wherein the data owner can trace unauthorized sharing of her/his biosignal data; and content authentication, wherein the data owner can prove whether the biosignal data has been maliciously altered. Based on experimentally collected datasets from a gait-stability monitoring BASN, we show that the embedding of 800 bit watermarks can be achieved robustly and effectively, with near-imperceptible changes to the signal waveform and no loss in the the signal's diagnostic quality.
    No preview · Article · Dec 2014
  • Teng Xu · Miodrag Potkonjak
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    ABSTRACT: Random Number Generator (RNG) plays an essential role in many sensor network systems and applications, such as security and robust communication. We have developed the first digital hardware random number generator (DHRNG). DHRNG has a small footprint and requires ultra-low energy. It uses a new recursive structure that directly targets efficient FPGA implementation. The core idea is to place or extract random values in FPGA configuration bits and randomly connect the building blocks. We present our architecture, introduce accompanying protocols for secure public key communication, and adopt the NIST randomness test on the DHRNG's output stream.
    No preview · Conference Paper · Nov 2013
  • Vishwa Goudar · Miodrag Potkonjak
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    ABSTRACT: We propose a novel strategy for energy-efficient operation of wireless monitoring devices under the premise that medical experts are primarily interested in atypical observations - For epilepsy monitoring, EEG data is most valuable at epileptic activity onset. Or, a gait-stability monitoring application is most interested in unusual footsteps. Observations are atypical if application-specific medical metrics and biosignal features are statistical outliers. Our strategy admits energy-efficient early-detection of such observations, leading to: (i) an increase in medical information quality by sampling aggressively over semantically important behaviors, and (ii) a savings in energy by precluding communication of typical measurements. From experimentally collected plantar pressure datasets, we show that this can yield up to a 62% improvement in gait-stability metric evaluation for atypical footsteps and a 10% energy cost reduction compared to a recently proposed non-adaptive compressive sensing technique.
    No preview · Conference Paper · Nov 2013
  • N.A. Conos · M. Potkonjak
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    ABSTRACT: Accurate thermal knowledge is essential for achieving ultra low power in deep sub-micron CMOS technology, as it affects gate speed linearly and leakage exponentially. We propose a temperature-aware synthesis technique that efficiently utilizes input vector control (IVC), dual-threshold voltage gate sizing (GS) and pin reordering (PR) for performing simultaneous delay and leakage power optimization. To the best of our knowledge, we are the first to consider these techniques in a synergistic fashion with thermal knowledge. We evaluate our approach by showing improvements over each method when considered in isolation and in conjunction. We also study the impact of employing considered techniques with/without accurate thermal knowledge. We ran simulations on synthesized ISCAS-85 and ITC-99 circuits on a 45 nm cell library while conforming to an industrial design flow. Leakage power improvements of up to 4.54X (2.14X avg.) were achieved when applying thermal knowledge over equivalent methods that do not.
    No preview · Conference Paper · Jan 2013
  • Sheng Wei · J.X. Zheng · M. Potkonjak
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    ABSTRACT: The presence of process variation (PV) in deep submicron technologies has become a major concern for energy optimization attempts on FPGAs. We develop a negative bias temperature instability (NBTI) aging-based post-silicon leakage energy optimization scheme that stresses the components that are not used or are off the critical paths to reduce the total leakage energy consumption. Furthermore, we obtain the input vectors for aging by formulating the aging objectives into a satisfiability (SAT) problem. We synthesize the low energy design on Xilinx Spartan6 FPGA and evaluate the leakage energy savings on a set of ITC99 and Opencores benchmarks.
    No preview · Conference Paper · Jan 2013
  • Teng Xu · J.B. Wendt · M. Potkonjak
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    ABSTRACT: We have developed a new security hardware primitive named digital bimodal function (DBF) that enables ultra low energy security protocols. DBF allows the computation of legitimate communicating sides to be compact and low-energy while it requires any attacker exponential computational effort and energy expense. Our new approach is competitive with the energy efficiency of traditional security key cryptographic security technique (e.g., AES) while more than three orders of magnitude more energy efficient than RSA. The implementation is demonstrated using the Xilinx FPGA platform.
    No preview · Conference Paper · Jan 2013
  • V. Goudar · Zhi Ren · P. Brochu · Qibing Pei · M. Potkonjak
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    ABSTRACT: As sensor equipped wearable systems enter the mainstream, system longevity and power-efficiency issues hamper large scale and long-term deployment, despite substantial foreseeable benefits. As power and energy efficient design, sampling, processing and communication techniques emerge to counter these issues, researchers are beginning to look on wearable energy harvesting systems as an effective counterpart solution. In this paper, we propose a novel harvesting technology to inconspicuously transduce mechanical energy from human foot-strikes and power low-power wearable systems in a self-sustaining manner. Dielectric Elastomers (DEs) are high-energy density electrostatic transducers that can transduce significant levels of energy from a user while appearing near-transparent to her, if configured and controlled properly. Towards this end, we propose DE-based harvester configuration that capitalizes on properties of human gait to enhance transduction efficiency, and further leverage these properties in an adaptive control algorithm to optimize the net energy produced by the system. We evaluate system performance from detailed analytical and empirical models of DE transduction behavior, and apply our control algorithm to the modeled DEs under experimentally collected foot pressure datasets from multiple subjects. Our evaluations show that the proposed system can achieve up to 120mJ per foot-strike, enough to power a variety of low-power wearable devices and systems.
    No preview · Conference Paper · Jan 2013
  • N.A. Conos · S. Meguerdichian · Sheng Wei · M. Potkonjak
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    ABSTRACT: Near-Threshold Computing (NTC) shows potential to provide significant energy efficiency improvements as it alleviates the impact of leakage in modern deep sub-micron CMOS technology. As the gap between supply and threshold voltage shrink, however, the energy efficiency gains come at the cost of device performance variability. Thus, adopting near-threshold in modern CAD flows requires careful consideration when addressing commonly targeted objectives. We propose a process variation-aware near-threshold voltage (PV-Nvt) gate sizing framework for minimizing power subject to performance yield constraints. We evaluate our approach using an industrial-flow on a set of modern benchmarks. Our results show our method achieves significant improvement in leakage power, while meeting performance yield targets, over a state-of-the-art method that does not consider near-threshold computing.
    No preview · Conference Paper · Jan 2013
  • Vishwa Goudar · Miodrag Potkonjak
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    ABSTRACT: We present a novel sampling method to overcome the tradeoff between sensing fidelity and energy-efficiency in the context of localized sensor arrays used by Body Area Networks (BANs). Prior research has tackled this tradeoff as a coverage problem, wherein a subset of sensors must cover the sensor field. Instead, we formulate it as a power-constrained sampling problem, limiting the number of samples taken per epoch to produce schedules with enhanced coverage and energy savings. This formulation capitalizes on the periodic nature and the strong spatio-temporal interactions that are innate to BAN sensor samples. Our algorithm produces schedules with over 170% in energy savings with increased sensor coverage that yields up to a 41% improvement in diagnostic estimates.
    No preview · Conference Paper · Oct 2012
  • James B. Wendt · Vishwa Goudar · Hyduke Noshadi · Miodrag Potkonjak
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    ABSTRACT: We present a new method for spatiotemporal assignment and scheduling of energy harvesters on a medical shoe tasked with measuring gait diagnostics. While prior work exists on the application of dielectric elastomers (DEs) for energy scavenging on shoes, current literature does not address the issues of placement and timing of these harvesters, nor does it address integration into existing sensing systems. We solve these issues and present a self-sustaining medical shoe that harvests energy from human ambulation while simultaneously measuring gait characteristics most relevant to medical diagnosis.
    No preview · Conference Paper · Oct 2012
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    J.X. Zheng · E. Chen · M. Potkonjak
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    ABSTRACT: In this paper we present the use of Benign Hardware Trojans (BHT) as a security measure for an embedded system with a software component and a hardware execution environment. Based on delay logic, process variation, and selective transistor aging, the BHT can be incorporated into an embedded system for the software and the hardware components to authenticate each other before functional execution. We will demonstrate an implementation of such a BHT within an embedded system on a Xilinx Spartan-6 FPGA platform. Using the same platform we will also show that the BHT security measurement has a low to modest amount of performance overhead basing on the test results from a variety of synthetic and real world benchmarks.
    Preview · Conference Paper · Jan 2012
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    J.B. Wendt · M. Potkonjak
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    ABSTRACT: We present a new nanotechnology PPUF-based architecture for trusted remote sensing. Current public physical unclonable function designs encompass complex circuits requiring high measurement accuracy and whose size slows down the authentication process. Our novel nanotechnology-based architecture ensures fast authentication through partial simulation while maintaining robust security. We authenticate over partitions in the design space in order to alleviate the authentication burden while still ensuring attack by simulation is entirely ineffective. We contribute new nanotechnology-based security protocols for authentication and time-stamping for trusted remote sensing.
    Full-text · Conference Paper · Dec 2011
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    J.B. Wendt · M. Potkonjak
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    ABSTRACT: Wearable sensing systems have facilitated a variety of applications in Wireless Health. Due to the considerable number of sensors and their constant monitoring these systems are often expensive and power hungry. Traditional approaches to sensor selection in large multisensory arrays attempt to alleviate these issues by removing redundant sensors while maintaining overall sensor predictability. However, predicting sensors is unnecessary if ultimately the system needs only to quantify diagnostic measurements specific to the application domain. We propose a new method for optimizing the design of medical sensor systems through diagnostic-based bottom-up sensor selection. We reduce the original sensor array from ninety nine to twelve sensors while maintaining a prediction error rate of less than 5% over all diagnostic metrics in our testing dataset.
    Full-text · Conference Paper · Dec 2011
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    S. Meguerdichian · M. Potkonjak
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    ABSTRACT: Hardware-based physically unclonable functions (PUFs) leverage intrinsic process variation of modern integrated circuits to provide interesting security solutions but either induce high storage requirements or require significant resources of at least one involved party. We use device aging to realize two identical unclonable modules that cannot be matched with any third such module. Each device enables rapid, low-energy computation of ultra-complex functions that are too complex for simulation in any reasonable time. The approach induces negligible area and energy costs and enables a majority of security protocols to be completed in a single or a few clock cycles.
    Preview · Conference Paper · Sep 2011
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    M. Potkonjak · Saro Meguerdichian · J.L. Wong
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    ABSTRACT: Remote trusted operation is essential for many types of sensors in an even greater number of applications. It is often crucial to secure guarantees that a particular sensor sample is taken by a specific sensor at a particular time and stated location. We present the first generic system architecture and security protocol that provides low cost, low power, and low latency trusted remote sensing. The approach employs already known randomized challenges and public physically unclonable function with a new concept of interleaved operational and security circuitry.
    Preview · Conference Paper · Dec 2010
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    M. Majzoobi · F. Koushanfar · M. Potkonjak
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    ABSTRACT: System security has emerged as a premier design requirement. While there has been an enormous body of impressive work on testing integrated circuits (ICs) desiderata such as manufacturing correctness, delay, and power, there is no reported effort to systematically test IC security in hardware. Our goal is to provide an impetus for this line of research and development by introducing techniques and methodology for rigorous testing of physically unclonable functions (PUFs). Recently, PUFs received a great deal of attention as security mechanisms due to their flexibility to form numerous security protocols and intrinsic resiliency against physical and side channels attacks. We study three classes of PUFs properties to design pertinent test methods: (i) predictability, (ii) sensitivity to component accuracy, and (iii) susceptibility to reverse engineering. As our case studies, we analyze two popular PUF structures, linear and feed-forward, and show that their security is not adequate from several points of view. The technical highlights of the paper are the first non-destructive technique for PUF reverse engineering and a new PUF structure that is capable of passing our security tests.
    Full-text · Conference Paper · Nov 2008
  • Conference Paper: (Bio)-Behavioral CAD
    M. Potkonjak · F. Koushanfar
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    ABSTRACT: We propose the use of functional magnetic resonance imaging (fMRI) systems, techniques, and tools to observe the neuron-level activity of the brains of designers or CAD tool developers. The objective is to enable designers and developers to complete their task in a faster and more creative way with significantly reduced number of logical and design errors. While fMRI techniques are already used in economics, decision and several other social sciences, until now their potential for closing the design productivity-silicon productivity (DPSP) gap has not been recognized. By compounding the new approach with techniques for designing integrated circuits and system within fMRI data collection and analysis, we will establish a positive productivity and creativity feedback loop that may permanently close the DPSP gap. As a preliminary and presently feasible step, we propose the creation of behavioral CAD research and development techniques. The usage of judiciously selected verbal, visual information and reintroduction of successful design paradigm and exposure to beneficial synthesis templates may help current and future designers to learn and design more effectively.
    No preview · Conference Paper · Jul 2008
  • J.L. Wong · Seapahn Megerian · M. Potkonjak
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    ABSTRACT: Inter-sensor modeling of data streams is an important problem and an enabler for numerous sensor network tasks such as faulty data detection, missing data recovery, and compression. We have developed a new symmetric monotonic regression (SMR) technique for predicting data at one sensor using data from another sensor or a set of sensors that simultaneously guarantees isotonicity and minimizes an arbitrary form of error for predicting stream X from stream Y and vice versa. Using a simple and fast algorithm, we also developed a lower bound regression (LBR) approach for evaluating the achievable accuracy of regression between the readings at two sensors. SMR often performs very close to the lower bound on a set of collected real-life sensor data. We show how LBR barrier can be outperformed by conducting prediction using either data from multiple sensors or by considering information extracted (multiple consecutive time samples) of the explanatory stream. The effectiveness of SMR is demonstrated on a sensor node sleeping coordination problem by reducing energy consumption by more than an order of magnitude with respect to the best previously published technique.
    No preview · Conference Paper · Mar 2007
  • J. Feng · Miodrag Potkonjak
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    ABSTRACT: We have developed a new error modeling and optimization-based localization approach for sensor networks in presence of distance measurement noise. The approach is solely based on the concept of consistency. The error models are constructed using non-parametric statistical techniques; they do not only indicate the most likely error, but also provide the likelihood distribution of particular errors occurring. The models are evaluated using the learn-and-test techniques and serve as the objective functions for the task of localization. The localization problem is formulated as task of maximizing consistency between measurements and calculated distances. We evaluated the approach in (i) both GPS-based and GPS-less scenarios; (ii) 1-D, 2-D and 3-D spaces, on sets of acoustic ranging-based distance measurements recorded by deployed sensor networks. The experimental evaluation indicates that localization of only a few centimeters is consistently achieved when the average and median distance measurement errors are more than a meter, even when the nodes have only a few distance measurements. The relative performance in terms of location accuracy compare favorably with respect to several state-of-the-art localization approaches. Finally, several insightful observations about the required conditions for accurate localization are deduced by analyzing the experimental results
    No preview · Conference Paper · Oct 2006

Publication Stats

3k Citations
54.52 Total Impact Points

Institutions

  • 1996-2013
    • University of California, Los Angeles
      • Department of Computer Science
      Los Ángeles, California, United States
  • 2008
    • Rice University
      • Department of Electrical and Computer Engineering
      Houston, TX, United States
  • 2007
    • Stony Brook University
      • Department of Computer Science
      Stony Brook, New York, United States
  • 2005
    • University of Wisconsin, Madison
      • Department of Electrical and Computer Engineering
      Madison, MS, United States
  • 1999
    • Cornell University
      • Department of Electrical and Computer Engineering
      Ithaca, NY, United States
  • 1989-1999
    • University of California, Berkeley
      • Department of Electrical Engineering and Computer Sciences
      Berkeley, California, United States
  • 1997
    • University of Massachusetts Amherst
      • Department of Electrical and Computer Engineering
      Amherst Center, Massachusetts, United States
  • 1994-1995
    • AT&T Labs
      Austin, Texas, United States
  • 1992-1995
    • NEC Laboratories America
      Princeton, New Jersey, United States