B. Moision

Broadcom Corporation, Irvine, California, United States

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Publications (59)27.47 Total impact

  • Bruce Moision, Sabino Piazzolla, Jon Hamkins
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    ABSTRACT: The Laser Communications Relay Demonstration (LCRD) will implement an optical communications link between a pair of Earth terminals via an Earth-orbiting satellite relay. Optical turbulence over the communication paths will cause random uctuations, or fading, in the received signal irradiance. In this paper we characterize losses due to fading caused by optical turbulence. We illustrate the performance of a representative relay link, utilizing a channel interleaver and error-correction-code to mitigate fading, and provide a method to quickly determine the link performance.
    Proc SPIE 03/2013;
  • William H. Farr, John M. Choi, Bruce Moision
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    ABSTRACT: Minimizing the mass and power burden of a laser transceiver on a spacecraft for interplanetary optical communications links drives requires operation in a "photon starved" regime. The relevant performance metric in the photon starved regime is Photon Information Efficiency (PIE) with units of bits per photon. Measuring this performance at the detector plane of an optical communications receiver, prior art has achieved performance levels around one bit per incident photon using pulse position modulation (PPM). By combining a PPM modulator with greater than 75 dB extinction ratio with a tungsten silicide (WSi) superconducting nanowire detector with greater than 83% detection efficiency we have demonstrated an optical communications link at 13 bits per incident photon.
    Proc SPIE 03/2013;
  • Bruce Moision, Baris I. Erkmen
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    ABSTRACT: Many errors contribute to the accuracy of a ranging system, among them calibration and estimation errors. In this paper we address the estimation error contribution of an optical ranging system. We present achievable RMS errors in estimating the phase, frequency, and intensity of a direct-detected intensity-modulated optical pulse train. For each parameter, the Cramèr-Rao-Bound (CRB) is derived and the performance of the Maximum Likelihood estimator is illustrated. Approximations to the CRBs are provided, enabling an intuitive understanding of estimator behavior as a function of the signaling parameters. The results are compared to achievable RMS errors in estimating the same parameters from a sinusoidal waveform in additive white Gaussian noise. This establishes a framework for a performance comparison of radio frequency (RF) and optical science. Comparisons are made using parameters for state-of-the-art deep-space RF and optical links. Degradations to the achievable errors due to clock phase noise and detector jitter are illustrated.
    Proc SPIE 10/2012;
  • Samuel Dolinar, Bruce Moision, Baris Erkmen
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    ABSTRACT: The performance of an intensity-modulated direct-detected optical communications link is degraded in turbulent media by spatial and temporal distortions of the signal. We discuss how to characterize and mitigate these losses. Article not available.
    03/2012;
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    ABSTRACT: A number of space agencies, including NASA, are considering free-space laser communications as a means for returning higher data-rates from future space missions. In this paper, potential deep-space missions are evaluated to show that with optical communication a 10× increase relative to state-of-the art telecommunication systems could be achieved. The maximum deep-space distance where ground transmitted laser beacons could assist acquisition and tracking; and operating points where optical communication performance degrades faster than the inverse square distance are also discussed.
    Proc SPIE 02/2012;
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    ABSTRACT: An ideal intensity-modulated photon-counting channel can achieve unbounded photon information efficiencies (PIEs). However, a number of limitations of a physical system limit the practically achievable PIE. In this paper, we discuss several of these limitations and illustrate their impact on the channel. We show that, for the Poisson channel, noise does not strictly bound PIE, although there is an effective limit, as the dimensional information efficiency goes as e-ePIE beyond a threshold PIE. Since the Holevo limit is bounded in the presence of noise, this illustrates that the Poisson approximation is invalid at large PIE for any number of noise modes. We show that a finite transmitter extinction ratio bounds the achievable PIE to a maximum that is logarithmic in the extinction ratio. We show how detector jitter limits the ability to mitigate noise in the PPM signaling framework. We illustrate a method to model detector blocking when the number of detectors is large, and illustrate mitigation of blocking with spatial spreading and filtering. Finally, we illustrate the design of a high photon efficiency system using state-of-the-art photo-detectors and taking all these effects into account.
    Proc SPIE 02/2012;
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    ABSTRACT: Coherent states achieve the Holevo capacity of a pure-loss channel when paired with an optimal measurement, but a physical realization of this measurement is unknown, and likely to be of high complexity. In this paper, we focus on the photon-counting measurement and study the photon and dimensional efficiencies attainable with modulations over classical- and nonclassical-state alphabets. We first review state-of-the-art coherent on-off-keying (OOK) and pulse-position modulation (PPM) with a photon-counting measurement, illustrating its asymptotic inefficiency relative to the Holevo limit. Then we analyze two architectures that improve upon the dimensional versus photon efficiency tradeoff achievable with conventional OOK or PPM. We show that at high photon efficiency these architectures achieve an efficiency tradeoff that differs from the best possible tradeoff by only a constant factor. The first architecture is a coherent-state transmitter that relies on feedback from the receiver to control the transmitted energy. The second architecture uses a single-photon number-state source.
    Information Theory Proceedings (ISIT), 2012 IEEE International Symposium on; 01/2012
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    ABSTRACT: Coherent states achieve the Holevo capacity of a pure-loss channel when paired with an optimal measurement, but a physical realization of this measurement is as of yet unknown, and it is also likely to be of high complexity. In this paper, we focus on the photon-counting measurement and study the photon and dimensional efficiencies attainable with modulations over classical- and nonclassical-state alphabets. We first review the state-of-the-art coherent on-off-keying (OOK) with a photon-counting measurement, illustrating its asymptotic inefficiency relative to the Holevo limit. We show that a commonly made Poisson approximation in thermal noise leads to unbounded photon information efficiencies, violating the conjectured Holevo limit. We analyze two binary-modulation architectures that improve upon the dimensional versus photon efficiency tradeoff achievable with conventional OOK. We show that at high photon efficiency these architectures achieve an efficiency tradeoff that differs from the best possible tradeoff—determined by the Holevo capacity—by only a constant factor. The first architecture we analyze is a coherent-state transmitter that relies on feedback from the receiver to control the transmitted energy. The second architecture uses a single-photon number-state source.
    Proc SPIE 01/2012;
  • Bruce Moision, Janet Wu, Shervin Shambayati
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    ABSTRACT: We describe work on the development of an optical link budget tool for an intensity-modulated direct-detected photon-counting channel utilizing pulse-position-modulation (PPM). We provide new material in several areas. First, we provide an approximation to the channel capacity, which is not known in closed form, to enable efficient search algorithms over the trade space. The expression also illustrates clearly the trade-offs between signal and noise power, and modulation parameters. We provide an approximation to the losses due to log-normal fading, which may be used to model scintillation. We provide approximations for the loss due to photo-detector blocking and jitter. Lastly, we describe a methodology to choose an optimum detector sub-array in the presence of dark noise, blocking, and an arbitrary point spread function.
    IEEE Aerospace Conference Proceedings 01/2012;
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    ABSTRACT: Optical communication at the quantum limit requires that measurements on the optical field be maximally informative, but devising physical measurements that accomplish this objective has proven challenging. The Dolinar receiver exemplifies a rare instance of success in distinguishing between two coherent states: an adaptive local oscillator is mixed with the signal prior to photodetection, which yields an error probability that meets the Helstrom lower bound with equality. Here we apply the same local-oscillator-based architecture with an information-theoretic optimization criterion. We begin with analysis of this receiver in a general framework for an arbitrary coherent-state modulation alphabet, and then we concentrate on two relevant examples. First, we study a binary antipodal alphabet and show that the Dolinar receiver's feedback function not only minimizes the probability of error, but also maximizes the mutual information. Next, we study ternary modulation consisting of antipodal coherent states and the vacuum state. We derive an analytic expression for a near-optimal local-oscillator feedback function, and, via simulation, we determine its photon information efficiency (PIE). We provide the PIE versus dimensional information efficiency (DIE) trade-off curve and show that this modulation and the our receiver combination performs universally better than (generalized) on-off keying plus photon counting, although, the advantage asymptotically vanishes as the bits-per-photon diverges towards infinity.
    Proc SPIE 09/2011;
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    ABSTRACT: We study the class of periodic-finite-type (PFT) shift spaces, which can be used to model time-varying constrained codes used in digital magnetic recording systems. A PFT shift is determined by a finite list of periodically forbidden words. We show that the class of PFT shifts properly contains all finite-type (FT) shifts, and the class of almost finite-type (AFT) shifts properly contains all PFT shifts. We establish several basic properties of PFT shift spaces of a given period T , and provide a characterization of such a shift in terms of properties of its Shannon cover (i.e., its unique minimal, deterministic, irreducible graph presentation). We present an algorithm that, given the Shannon cover G of an irreducible sofic shift X , decides whether or not X is PFT in time that is quadratic in the number of states of G . From any periodic irreducible presentation of a given period, we define a periodic forbidden list, unique up to conjugacy (a circular permutation) for that period, that satisfies certain minimality properties. We show that an irreducible sofic shift is PFT if and only if the list corresponding to its Shannon cover G and its period is finite. Finally, we discuss methods for computing the capacity of a PFT shift from a periodic forbidden list, either by construction of a corresponding graph or in a combinatorial manner directly from the list itself.
    IEEE Transactions on Information Theory 07/2011; · 2.62 Impact Factor
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    ABSTRACT: It is well known that ideal free-space optical communication at the quantum limit can have unbounded photon information efficiency (PIE), measured in bits per photon. High PIE comes at a price of low dimensional information efficiency (DIE), measured in bits per spatio-temporal-polarization mode. If only temporal modes are used, then DIE translates directly to bandwidth efficiency. In this paper, the DIE vs. PIE tradeoffs for known modulations and receiver structures are compared to the ultimate quantum limit, and analytic approximations are found in the limit of high PIE. This analysis shows that known structures fall short of the maximum attainable DIE by a factor that increases linearly with PIE for high PIE. The capacity of the Dolinar receiver is derived for binary coherent-state modulations and computed for the case of on off keying (OOK). The DIE vs. PIE tradeoff for this case is improved only slightly compared to OOK with photon counting. An adaptive rule is derived for an additive local oscillator that maximizes the mutual information between a receiver and a transmitter that selects from a set of coherent states. For binary phase-shift keying (BPSK), this is shown to be equivalent to the operation of the Dolinar receiver. The Dolinar receiver is extended to make adaptive measurements on a coded sequence of coherent state symbols. Information from previous measurements is used to adjust the a priori probabilities of the next symbols. The adaptive Dolinar receiver does not improve the DIE vs. PIE tradeoff compared to independent transmission and Dolinar reception of each symbol.
    Space Optical Systems and Applications (ICSOS), 2011 International Conference on; 06/2011
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    Bruce Moision, Sabino Piazzolla
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    ABSTRACT: Many photon-counting photo-detectors have the property that they become inoperative for some time after detection event. We say the detector is blocked during this time. Blocking produces losses when using the detector as a photon- counter to detect a communications signal. In this paper, we characterize blocking losses for single detectors and for arrays of detectors. For arrays, we discuss conditions under which the output may be approximated as a Poisson point process, and provide a simple approximation to the blocking loss. We show how to extend the analysis to arrays of non-uniformly illuminated arrays and provide numerical methods to accurately predict count rates for detectors with exponential recovery from the blocked state. I. INTRODUCTION Many photon-counting photo-detectors have the property that they become inoperative for some time after detection event. We say the detector is blocked during this time. When used to detect a communications signal, blocking leads to losses relative to an ideal detector, which may be measured as a reduction in the communications rate for a given received signal power, or a increase in the signal power required to support the same communications rate In this paper, we characterize blocking losses for single detectors and for arrays of detectors. Throughout we assume the communications signal is inten- sity modulated, and received by an array of photon-counting photo-detectors. For the purpose of this analysis, we assume the detectors are ideal, in that they produce a signal that allows one to reproduce the arrival times of electrons, produced either as photo-electrons or from dark noise, exactly. For single detectors, we illustrate the performance of the maximum- likelihood(ML) receiver in blocking, as well as a maximum- count(MC) receiver, that, when receiving a pulse-position- modulated(PPM) signal, selects the symbol corresponding to the slot with the largest electron count. We show that whereas the MC receiver saturates at high count rates, the ML receiver may not. We numerically compute the loss in capacity, symbol- error-rate (SER), and count-rate. We show that the capacity and symbol-error-rate losses track, whereas the count-rate loss does not, generally, reflect the SER or capacity loss, as the slot-statistics at the detector output are no longer Poisson. We show that the MC receiver loss may be accurately predicted for dead-times on the order of a slot, by using the exact statistics provided in (1). Blocking may be mitigated by spreading the signal intensity over an array of detectors, reducing the count rate on any one detector. We discuss conditions under which the sum of the arrayed detectors may be approximated as a Poisson point process, and provide a simple approximation to the blocking loss as a function of the probability that a detector is unblocked at a given time, essentially treating the blocking probability as a scaling of the detection efficiency. We show how to extend the analysis to arrays of non-uniformly illuminated arrays. We also discuss incorporating a more accurate model of the blocking phenomenon, wherein the detector is blocked for some time, then has a recovery of its detection efficiency to the steady-state value. We illustrate in the Appendix how to accurately model the reduction in count rate for such a detector, and show that the additional loss due to the recovery time may be modeled by extending the blocking duration.
    01/2011;
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    IEEE Transactions on Information Theory 01/2011; 57:3677-3691. · 2.62 Impact Factor
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    ABSTRACT: This paper presents and compares two iterative coded modulation techniques for deep-space optical communications using pulse-position modulation (PPM). The first code, denoted by SCPPM, consists of the serial concatenation of an outer convolutional code, an interleaver, a bit accumulator, and PPM. The second code, denoted by LDPC-PPM, consists of the serial concatenation of an LDPC code and PPM. We employ Extrinsic Information Transfer (EXIT) charts for their analysis and design. Under conditions typical of a communications link from Mars to Earth, SCPPM is 1 dB away from capacity, while LDPC-PPM is 1.4 dB away from capacity, at a Bit Error Rate (BER) of approximately 10<sup>-5</sup>. However, LDPC-PPM lends itself naturally to low latency parallel processing in contrast to SCPPM.
    IEEE Transactions on Communications 01/2011; · 1.75 Impact Factor
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    ABSTRACT: Recently a conceptual design study titled Deep-space Optical Terminals (DOT) was completed for a deep-space optical communication technology demonstration in the 2018 timeframe. This article provides an overview of the system engineering portion of the study. The Level 1 requirements received from the NASA Space Communications and Navigation Program Manager emphasized an order of magnitude higher data rate from Mars closest range relative to the Ka-band telecommunication system flown on the Mars Reconnaissance Orbiter (MRO) mission but utilizing comparable mass and power. The system-level concept design motivated by this driving requirement and reported here describes link performance of 267 Mb/s from 0.42 AU within an allocated mass and power of 38 kg and 110 W. Furthermore, the concept design addresses link closure at the farthest Mars range of 2.7 AU. Maximum uplink data rates of 292 kb/s and ranging with 30-cm precision are also addressed.
    Interplanetary Network Progress Report. 11/2010;
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    ABSTRACT: There is considerable interest in determining whether suitably modified versions of existing 34-meter antennas at NASA's Goldstone Communications Complex, originally designed for X-band (nominally 8 GHz) and Ka-band (32 GHz) operation, could also be used to receive near-infrared optical signals. The robust backup structure of these antennas, together with extremely large collecting apertures and milli-degree pointing capabilities suggest that dual RF/Optical communications may indeed be possible, at optical data-rates approaching 1 gigabit per second (GBPS) from typical Mars distances. Several design concepts have emerged as possible candidates, requiring modifications ranging from polishing and coating of the existing aluminum panels of the main reflector, to significant redesign involving replacement of the panels with optical reflectors. Optical receiver parameters such as collecting area, field-of-view (FOV), and immunity to reflected sunlight differ markedly for each design concept, hence will likely lead to different levels of performance in terms of data-throughput at a given BER, and in terms of the ability to point close to the sun. The communications performance of two candidate design concepts operating under realistic daytime conditions is evaluated, with particular emphasis on spatial and temporal acquisition algorithms and receiver optimization to achieve the best possible communication performance at high data rates.
    Aerospace Conference, 2010 IEEE; 04/2010
  • Baris I. Erkmen, Bruce E. Moision, Kevin M. Birnbaum
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    ABSTRACT: We provide a summary of the classical information capacity of single-mode free-space optical communication for pure-loss channels. We compare the capacities afforded by structured transmitters and receivers to that of the ultimate communication capacity dictated by the quantum nature of light, and we draw the following conclusions. The ultimate capacity can be achieved with classical coherent states (i.e., ideal laser light), but the capacity-achieving receiver (measurement) is yet to be determined. In photon-starved pure-loss channels, binary phase modulation in combination with the optimal receiver is near-capacity achieving, and more importantly, it is superior to on-off keying with either the optimal receiver (as yet to be determined) or with a photon-counter. Heterodyne detection approaches the ultimate capacity at high mean photon numbers.
    Proc SPIE 02/2010;
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    ABSTRACT: We give a brief summary of the classical information capacity of single-mode free-space optical communication, both for pure-loss channels (i.e., with no background radiation), and for thermal-noise channels (i.e., with background radiation). We compare the capacities afforded by structured transmitters and receivers to that of the ultimate communication capacity. The ultimate capacity-achieving optical states are classical coherent states (i.e., ideal laser light), but the capacity-achieving receiver is yet to be determined. In addition, in photon-starved pure-loss channels, binary phase modulation in combination with the optimal receiver is near-capacity achieving, and more importantly, it is superior to on-off keying. In a pure-loss channel, heterodyne detection is near-optimal at high signal levels. In thermal-noise channels with high background noise and low signal we find that homodyne and heterodyne detection both approach the ultimate capacity, and at high signal heterodyne detection remains near-optimal. Finally, we quantify the degradation in channel capacity that is due to multiple noise modes contributing to the output of photon-counters.
    Interplanetary Network Progress Report. 11/2009;
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    B.I. Erkmen, B. Moision
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    ABSTRACT: Many optical imaging, ranging, and communications systems rely on the estimation of the arrival time of an optical pulse. In systems utilizing photon-counting photodetectors, which are finding increased use, the detected process is well modeled as a Poisson point process. In this paper, we analyze the performance of maximum likelihood (ML) estimators of the arrival time of an optical pulse, based on observations of a Poisson process. We develop an analytic model for the mean-square error of the ML estimator, illustrating two phenomena that cause deviations from the Cramer-Rao bound at low signal photon flux. The model accurately predicts the ML performance over all regimes considered. We also derive an approximation to the threshold at which the ML estimator essentially fails to provide better than a random guess of the pulse arrival time.
    Information Theory, 2009. ISIT 2009. IEEE International Symposium on; 08/2009

Publication Stats

373 Citations
27.47 Total Impact Points

Institutions

  • 2011
    • Broadcom Corporation
      Irvine, California, United States
    • Université Paris-Est Marne-la-Vallée
      • Laboratoire d'Informatique Gaspard-Monge
      Champs-sur-Marne, Ile-de-France, France
  • 2001–2011
    • California Institute of Technology
      • Jet Propulsion Laboratory
      Pasadena, CA, United States
  • 1998–2007
    • University of California, San Diego
      • Department of Electrical and Computer Engineering
      San Diego, California, United States