M. Potkonjak

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

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Publications (175)88.34 Total impact

  • Source
    J.H. Ahnn · M. Potkonjak
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    ABSTRACT: Although mobile health monitoring where mobile sensors continuously gather, process, and update sensor readings (e.g. vital signals) from patient's sensors is emerging, little effort has been investigated in an energy-efficient management of sensor information gathering and processing. Mobile health monitoring with the focus of energy consumption may instead be holistically analyzed and systematically designed as a global solution to optimization subproblems. We propose a distributed and energy-saving mobile health platform, called mHealthMon where mobile users publish/access sensor data via a cloud computing-based distributed P2P overlay network. The key objective is to satisfy the mobile health monitoring application's quality of service requirements by modeling each subsystem: mobile clients with medical sensors, wireless network medium, and distributed cloud services. By simulations based on experimental data, we present the proposed system can achieve up to 10.1 times more energy-efficient and 20.2 times faster compared to a standalone mobile health monitoring application, in various mobile health monitoring scenarios applying a realistic mobility model.
    Engineering in Medicine and Biology Society (EMBC), 2013 35th Annual International Conference of the IEEE; 01/2013
  • 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.
    Field Programmable Logic and Applications (FPL), 2013 23rd International Conference on; 01/2013
  • 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.
    Low Power Electronics and Design (ISLPED), 2013 IEEE International Symposium on; 01/2013
  • 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.
    Power and Timing Modeling, Optimization and Simulation (PATMOS), 2013 23rd International Workshop on; 01/2013
  • Teng Xu · M. 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.
    Sensors, 2013 IEEE; 01/2013
  • 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.
    Power and Timing Modeling, Optimization and Simulation (PATMOS), 2013 23rd International Workshop on; 01/2013
  • V. Goudar · M. 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.
    Sensors, 2013 IEEE; 01/2013
  • 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.
    Computer Design (ICCD), 2013 IEEE 31st International Conference on; 01/2013
  • N.A. Conos · S. Meguerdichian · M. Potkonjak
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    ABSTRACT: We introduce a novel gate sizing approach that considers both the gate switching activity (SA) and gate input vector control leakage (IVC). We first extract SA using simulation and find promising input vectors. Next, in an iterative framework, we interchangeably conduct gate sizing and refining the IVC. As dictated by the new objective function, our algorithm conducts iterative gate freezing and unlocking with cut-based search for the most beneficial gate sizes under delay constraints. We evaluate our approach on standard benchmarks in 45 nm technology, showing promising improvement, achieving up to 62% (29% avg.) energy savings compared to the traditional objective function.
    Very Large Scale Integration (VLSI-SoC), 2013 IFIP/IEEE 21st International Conference on; 01/2013
  • S. Meguerdichian · M. Potkonjak
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    ABSTRACT: Hardware-based physically unclonable functions (PUFs) are elegant security primitives that leverage process variation inherent in modern integrated circuits. Recently proposed matched public PUFs (mPPUFs) use a combination of coordinated device aging and gate disabling to create two PUFs that securely realize identical input-output mappings. However, mPPUFs of any reasonable size allow for protocols between only a very limited number of parties. We propose quantization of possible delay values to enable matching of an unbounded number of arbitrary PPUF instances, improving stability in the presence of fluctuations in temperature or supply voltage while maintaining resiliency against a wide number of attacks.
    Computer-Aided Design (ICCAD), 2012 IEEE/ACM International Conference on; 01/2012
  • Source
    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.
    Field Programmable Logic and Applications (FPL), 2012 22nd International Conference on; 01/2012
  • J.B. Wendt · V. Goudar · H. Noshadi · M. 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.
    Sensors, 2012 IEEE; 01/2012
  • V. Goudar · M. Potkonjak
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    ABSTRACT: Parasitic energy scavenging from human-generated vibrations with piezoelectric materials has long been studied in contrast to electromagnetic or conventional electrostatic transducers. Dielectric Elastomers (DEs) are now gaining notice as low-cost electrostatic transducers with high energy densities. However, their transduction mechanism is more intricate. DE Generators (DEGs) are functionally variable capacitors, which require fine-grained control of their charging cycles in order to maximize the energy transduced. Based on a detailed DEG model that incorporates an effective method to time the charge cycles, we contrast the energy scavenged from shoe strikes by DEGs that are virtually embedded into the shoe sole, to similar piezoelectric generators. This comparison for a plantar pressure dataset of a walking subject demonstrates a multiple order-of-magnitude improvement in harvested energy.
    Sensors, 2012 IEEE; 01/2012
  • V. Goudar · M. 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.
    Sensors, 2012 IEEE; 01/2012
  • Sheng Wei · Kai Li · F. Koushanfar · M. Potkonjak
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    ABSTRACT: This paper proposes a novel minimal test point insertion methodology that provisions a provably complete detection of hardware Trojans by noninvasive timing characterization. The objective of test point insertion is to break the reconvergent paths so that target routes for Trojan delay testing are specifically observed. We create a satisfiability-based input vector selection for sensitizing and characterizing each single timing path. Evaluations on benchmark circuits demonstrate that the test point-based Trojan detection can cover all circuit locations and can detect Trojans accurately with less than 5% performance overhead.
    Computer-Aided Design (ICCAD), 2012 IEEE/ACM International Conference on; 01/2012
  • Source
    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.
    Sensors, 2011 IEEE; 12/2011
  • Source
    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.
    Sensors, 2011 IEEE; 12/2011
  • Source
    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.
    Low Power Electronics and Design (ISLPED) 2011 International Symposium on; 09/2011
  • Source
    Sheng Wei · M. Potkonjak
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    ABSTRACT: Hardware Trojans (HTs) pose a significant threat to the modern and pending integrated circuit (IC). Several approaches have been proposed to detect HTs, but they are either incapable of detecting HTs under the presence of process variation (PV) or unable to handle very large circuits in the modern IC industry. We develop a scalable HT detection and diagnosis scheme by using segmentation techniques and gate level characterization (GLC). In order to address the scalability issue, we propose a segmentation method which divides the large circuit into small sub-circuits by using input vector control. We propose a segment selection model in terms of properties of segments and their effects on GLC accuracy. The model parameters are calibrated by sampled data from the GLC process. Based on the selected segments we are able to detect and diagnose HTs correctly by tracing gate level leakage power. We evaluate our approach on several ISCAS85/ISCAS89/ITC99 benchmarks. The simulation results show that our approach is capable of detecting and diagnosing HTs accurately on large circuits.
    Computer-Aided Design (ICCAD), 2010 IEEE/ACM International Conference on; 12/2010
  • Source
    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.
    Sensors, 2010 IEEE; 12/2010

Publication Stats

4k Citations
88.34 Total Impact Points

Institutions

  • 1996–2013
    • University of California, Los Angeles
      • Department of Computer Science
      Los Angeles, 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
  • 2006
    • University of Incheon
      • Department of Electronics Engineering
      Seoul, Seoul, South Korea
  • 2005
    • University of Wisconsin, Madison
      • Department of Electrical and Computer Engineering
      Madison, MS, United States
  • 2003
    • Microsoft
      Washington, West Virginia, United States
  • 2000
    • Mountain View Pharmaceuticals, Inc.
      Menlo Park, California, United States
    • University of Virginia
      • Department of Electrical and Computer Engineering (ECE)
      Charlottesville, VA, United States
  • 1992–2000
    • NEC Laboratories America
      Princeton, New Jersey, United States
  • 1999
    • Synopsys
      Mountain View, California, United States
    • Cornell University
      • Department of Electrical and Computer Engineering
      Ithaca, NY, United States
  • 1998
    • California State University
      • Department of Electrical & Computer Engineering
      Long Beach, California, United States
  • 1997
    • University of Massachusetts Amherst
      • Department of Electrical and Computer Engineering
      Amherst Center, Massachusetts, United States
  • 1994–1996
    • AT&T Labs
      Austin, Texas, United States
  • 1989–1996
    • University of California, Berkeley
      • Department of Electrical Engineering and Computer Sciences
      Berkeley, MO, United States
  • 1995
    • Massachusetts Institute of Technology
      Cambridge, Massachusetts, United States