Papers by Mostofa Howlader
IEEE Communications Letters, 2001
This letter proposes a decoder-assisted frame synchronization scheme for convolutionally encoded ... more This letter proposes a decoder-assisted frame synchronization scheme for convolutionally encoded information packets. Rather than placing sync bits in a separate header, the sync bits are placed in a mid-amble and encoded as part of the information sequence, using the error correction encoder to resolve time ambiguities. This technique requires fewer bits for frame synchronization. The performance improvement over the conventional synchronization technique is explored via simulation.
Issues Associated with Deploying Wireless Systems in Nuclear Facilities
This paper discusses the technical issues that should be addressed if wireless communications sys... more This paper discusses the technical issues that should be addressed if wireless communications systems are to be deployed in safety-related instrumentation and control applications in nuclear facilities. Distributed data communications networks are nothing new in nuclear facilities and are presently an integral part of safety operations. Although originally intended for wired networks, the safety and analysis framework for these data communications networks can also be applied to wireless communications. Wireless communications do not introduce any new types of communications errors, but the probabilities of the errors do differ between wired and wireless networks. Issues important for the deployment of wireless systems include coexistence, reliability, signal propagation, and regulatory impact. Coexistence studies are essential to quantify the effects of electromagnetic interference on communications links and can incorporate any combination of three evaluation approaches: analysis,...
Time-averaged electron number density measurement of a one atmosphere uniform glow discharge plasma (OAUDGP) by absorption of microwave radiation
Summary form only given. A simple and accurate technique for measuring the time-averaged electron... more Summary form only given. A simple and accurate technique for measuring the time-averaged electron number density of a plasma at atmospheric pressure is described. It is based on the angle-of-incidence dependent response of the plasma absorption to the incident microwave signal. The method is applied to determine the time-averaged electron number density of a One Atmosphere Uniform Glow Discharge Plasma
Electric utilities have a main responsibility to protect the lives and safety of their workers wh... more Electric utilities have a main responsibility to protect the lives and safety of their workers when they are working on low-, medium-, and high-voltage power lines and distribution circuits. With the anticipated widespread deployment of smart grids, a secure and highly reliable means of maintaining isolation of customer-owned distributed generation (DG) from the affected distribution circuits during maintenance is necessary to provide a fully de-energized work area, ensure utility personnel safety, and prevent hazards that can lead to accidents such as accidental electrocution from unanticipated power sources. Some circuits are serviced while energized (live line work) while others are deenergized for maintenance. For servicing de-energized circuits and equipment, lock-out tag-out (LOTO) programs provide a verifiable procedure for ensuring that circuit breakers are locked in the off state and tagged to indicate that status to operational personnel so that the lines will be checked for voltage to verify they are de-energized. The de-energized area is isolated from any energized sources, which traditionally are the substations. This procedure works well when all power sources and their interconnections are known-armed with this knowledge, utility personnel can determine the appropriate circuits to de-energize for isolating the target line or equipment. However, with customerowned DG tied into the grid, the risk of inadvertently reenergizing a circuit increases because circuit connections may not be adequately documented and are not under the direct control of the local utility. Thus, the active device may not be properly de-energized or isolated from the work area. Further, a remote means of de-energizing and locking out energized devices provides an opportunity for greatly reduced safety risk to utility personnel compared to manual operations. In this paper, we present a remotely controllable LOTO system that allows individual workers to determine the configuration and status of electrical system circuits and permit them to lock out customer-owned DG devices for safety purposes using a highly secure and ultra-reliable radio signal. The system consists of: (1) individual personal lockout devices, (2) lockout communications and logic
Issues Associated with Deploying Wireless Systems
The Energy Citations Database (ECD) provides access to historical and current research (1948 to t... more The Energy Citations Database (ECD) provides access to historical and current research (1948 to the present) from the Department of Energy (DOE) and predecessor agencies.
Intersymbol Interference Due to the Atmospheric Turbulence for Free-Space Optical Communication System
2007 Ieee International Conference on Communications, Jun 24, 2007
Weak atmospheric turbulence causes pulse broadening of an optical signal. In this article, we dri... more Weak atmospheric turbulence causes pulse broadening of an optical signal. In this article, we drive the pulse broadening as a function of turbulence strength by temporal moments directly. We derive pulse broadening dependency on turbulence strength and propagation distance when an optical signal propagates through atmosphere. This pulse broadening induces intersymbol interference (ISI) between adjacent pulses. Based on this derived results, we develop some observation patterns using a practical example.
Noncoherent decoder-assisted frame synchronization for packet transmission
Wireless Communications Ieee Transactions on, May 1, 2006
Automotive Geolocation Using Wireless Infrastructure in a GPS Denied Environment
The article proposes a vehicle lane positioning technique based on joint frequency difference of ... more The article proposes a vehicle lane positioning technique based on joint frequency difference of arrival (FDOA) and time difference of arrival (TDOA) principle by measuring Doppler frequency, and derives possible solutions. The vehicle sensor measures the incoming RF signals from a reference emitter at time delayed locations and utilizes the characteristics of this downlink communications to accurately determine the frequency offset as well as time stamp of the packet. The article also addresses the limitations of the technique such as velocity vector estimations at measurement locations and offers possible solutions including Bayesian and triangulation estimation.
A Simulink® model for Direct Sequence Spread Spectrum (DSSS) receiver is presented. Using data-pa... more A Simulink® model for Direct Sequence Spread Spectrum (DSSS) receiver is presented. Using data-path size as an additional parameter in the model blocks made it possible to do the hardware optimization of the receiver on the block-by-block basis. The effect of the round-off errors to the bit-error rate (BER) of the receiver is quantified for each block in the model. Different functional parts of the receiver, such as analog-to-digital converter (ADC), digital down-converter (DDC), matched filter, are shown to have different sensitivity to the data-path size. Using multivariable optimization, one can use the model to minimize the hardware implementation with respect to the BER. Keywords Digital down-converter, matched filter, analog-to-digital converter round-off error.
Measurements of Electron Number Density and Electron Collision Frequency in a One Atmosphere Uniform Glow Discharge Plasma Using a Microwave Network Analyzer
Measuring the electron number density and collision frequency is crucial to understanding the beh... more Measuring the electron number density and collision frequency is crucial to understanding the behavior and transport coefficients of an atmospheric pressure plasma. We describe a technique to characterize these parameters in a quantitative and non-perturbing way. The technique uses a microwave network analyzer system to measure the absorption and phase shift of a propagating 15 GHz microwave signal. These measured quantities are related to the real and imaginary parts of the plasma index of refraction, which is described by Appleton's equation. Since the electron number density and collision frequency can be numerically derived from the absorption and phase shift that are measured quantities, one need not know the electron energy distribution function, the electron kinetic temperature, or the electron energy-dependent cross section for the collision process. The electron collision frequency is sufficient to determine the transport coefficients, including the diffusion coefficien...
Wireless Network Security in Nuclear Facilities
<title>Negligible polarization aberrations of antireflection-coated paraxial optical systems</title>
Polarization Analysis and Measurement IV, 2002
ABSTRACT We show that antireflection-coated (ARC) optical systems with numerical apertures &l... more ABSTRACT We show that antireflection-coated (ARC) optical systems with numerical apertures &lt; 1 exhibit negligible polarization aberrations of the fourth and sixth order for the retardance and di-attenuation, respectively. Results for ARC high-index optics are presented as examples.
Measurement of Dielectric Properties of Materials using Transmis sion/Reflection Method with Material filled Transmission Line
2005 IEEE Instrumentationand Measurement Technology Conference Proceedings, 2005
Real-time complex permeability and permittivity measurement and instantaneous examination of the ... more Real-time complex permeability and permittivity measurement and instantaneous examination of the results are possible with the help of modern measurement equipments like vector network analyzer and computer software control. In this paper a simple procedure with the combination of hardware and software tools is presented for measuring the material properties with sample material filled coaxial and waveguide transmission line sections. Transmission and reflection method is used for simultaneous determination of the complex dielectric properties of a given sample material. Some mathematical formulas have been derived which includes the loss of the material in the phase compensation that is required in the measurement procedure. Complete software has been developed to get the measurement results and calculate the permeability and permittivity of any sample material instantaneously. The experimental results have been compared with the simulation results to prove the validity of this new measurement approach
Noncoherent decoder-assisted frame synchronization for packet transmission
2004 IEEE International Conference on Communications (IEEE Cat. No.04CH37577), 2004
Serial concatenated MSK modulated space-time block coding
2004 IEEE International Conference on Communications (IEEE Cat. No.04CH37577), 2004
ABSTRACT In this article, we propose iterative noncoherent (without knowledge of fading phase) an... more ABSTRACT In this article, we propose iterative noncoherent (without knowledge of fading phase) and non-CSI (without knowledge of fading phase and amplitude) decoding for space-time block coding (STBC) by employing MSK modulation instead of commonly used PSK. Beyond a simple replacement, MSK modulated STBC (MSK-STBC) reduces the smallest resolvable time interval from STBC code duration, necessary for differential space-time coding (DST), to MSK symbol duration, and thus presents consistent and enhanced system performance in fast fading channels. The efficiency of our schemes is validated and illustrated via theoretical analysis and numerical simulations.
Decoder-assisted noncoherent frame synchronization for burst OFDM-based packet transmission
GLOBECOM '05. IEEE Global Telecommunications Conference, 2005., 2005
This paper proposes a noncoherent decoder-assisted (NDA) frame synchronization methodology for OF... more This paper proposes a noncoherent decoder-assisted (NDA) frame synchronization methodology for OFDM packets using the list-synchronization technique [MMK Howlander et al., 2001] for serially concatenated coded differential modulation (SCCD) systems [KR Narayanan et al, 1999], where a conventional MMSE rule based on the supplementary guard interval [M Speth et al., 1998] synchronizer in the time domain generates a list of
Noncoherent iterative demodulation and decoding of serially concatenated coded MSK
IEEE Global Telecommunications Conference, 2004. GLOBECOM '04., 2004
In this paper, we propose a detection technique for a serially concatenated coded MSK (SC-MSK) mo... more In this paper, we propose a detection technique for a serially concatenated coded MSK (SC-MSK) modulated signal, based on the noncoherent BCJR (N-BCJR) algorithm, where an exponentially decaying observation window (EDW) in the N-BCJR algorithm is used to get better use of the channel phase memory and reduce the state as well as metric computational complexity. We also derive the
Research directions for fourth generation wireless
Proceedings Tenth IEEE International Workshop on Enabling Technologies: Infrastructure for Collaborative Enterprises. WET ICE 2001, 2001
ABSTRACT
Analysis of a new hybrid interference cancellation (HIC) system
2004 IEEE Wireless Communications and Networking Conference (IEEE Cat. No.04TH8733), 2004
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Papers by Mostofa Howlader