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Advanced communications

Wireless (RF)

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Published Date
Displaying 601 - 625 of 648

Interference Avoidance in Rapidly Deployed Wireless Ad hoc Incident Area Networks

April 18, 2008
Author(s)
Mohamed T. Refaei, Nader Moayeri, Michael R. Souryal
A common strategy for responding to indoor emergency scenarios is to rapidly deploy a group of first responders inside the incident area and an incident command center outside of the incident area. First responders are equipped with radios that allow them

Quantize-and-Forward Relaying with M-ary Phase Shift Keying

March 31, 2008
Author(s)
Michael R. Souryal, Huiqing You
Using cooperative transmission, two or more single-antenna users can share their antennas to achieve spatial diversity in a slow fading channel. One relaying protocol that achieves diversity, amplify-and-forward (AF), is striking in its simplicity, but

Comb-Generator Characterization

February 1, 2008
Author(s)
Howard C. Reader, Dylan Williams, Paul D. Hale, Tracy S. Clement
We characterize a 50 GHz comb generator measured on a sampling oscilloscope. With careful control of the input power, input harmonics and comb generator temperature, we find the output spectrum to be stable to 0.1 dB and 0.5 degrees. We correct results for

Soft-Decision Metrics for Coded Orthogonal Signaling in Symmetric Alpha-Stable Noise

January 1, 2008
Author(s)
Michael R. Souryal, E G. Larsson, B M. Peric, B R. Vojcic
This paper derives new soft decision metrics for coded orthogonal signaling in impulsive noise, more specifically symmetric alpha-stable noise. For the case of a known channel amplitude and known noise dispersion, exact metrics are derived both for Cauchy

Guide to Storage Encryption Technologies for End User Devices

November 15, 2007
Author(s)
Karen A. Scarfone, Murugiah P. Souppaya, Matt Sexton
Many threats against end user devices, such as desktop and laptop computers, smart phones, personal digital assistants, and removable media, could cause information stored on the devices to be accessed by unauthorized parties. To prevent such disclosures

Nanosecond Delay With Subpicosecond Uncertainty

September 1, 2007
Author(s)
Donald R. Larson, Nicholas Paulter
We have combined a commercially available, variable length coaxial delay line (trombone line) with a high resolution linear translation system. The result is better resolution and lower uncertainty in the achievable delays than previously available. The

Real-Time Deployment of Multihop Relays for Range Extension

June 11, 2007
Author(s)
Michael R. Souryal, Johannes Geissbuehler, Leonard E. Miller, Nader Moayeri
When the range of single-hop wireless communication is limited by distance or harsh radio propagation conditions, relays can be used to extend the communication range through multihop relaying. This paper targets the need in certain scenarios for rapid

Securing Radio Frequency Identification (RFID) Systems

May 17, 2007
Author(s)
Karen A. Scarfone
Radio frequency identification (RFID) is a form of automatic identification and data capture technology that uses electric or magnetic fields at radio frequencies to transmit information. An RFID system can be used to identify many types of objects, such

Cell Phone Forensic Tools: An Overview and Analysis Update

March 21, 2007
Author(s)
Richard Ayers, Wayne Jansen, Aurelien M. Delaitre, Ludovic Moenner
Cell phones and other handheld devices incorporating cell phone capabilities (e.g., Personal Digital Assistant (PDA) phones) are ubiquitous. Rather than just placing calls, certain phones allow users to perform additional tasks such as SMS (Short Message

Establishing Wireless Robust Security Networks: A Guide to IEEE 802.11i

February 7, 2007
Author(s)
Sheila E. Frankel, Bernard Eydt, L Owens, Karen Kent Scarfone
This report provides readers with a detailed explanation of next generation 802.11 wireless security. It describes the inherently flawed Wired Equivalent Privacy (WEP) and explains 802.11i's two-step approach (interim and long-term)to providing effective

A Measurement of Propagation Delay

January 16, 2007
Author(s)
Donald R. Larson, Nicholas Paulter
A measurement method and associated uncertainty analysis have been developed for the measurement of propagation or group delay in electrical transmission lines and optical fibers. The measurement method and uncertainty analysis were applied to measurements

Eliminating FFT Artifacts in Vector Signal Analyzer Spectra

October 1, 2006
Author(s)
Michael McKinley, Kate Remley, M. Myslinski, J. S. Kenney
We present a method to minimize spectral leakage in measurements of periodic signals made with the vector signal analyzer (VSA) by taking into account the periodic nature of the Fast Fourier Transform (FFT). This method negates the need for filtering the

Link Assessment in an Indoor 802.11 Network

April 1, 2006
Author(s)
Michael R. Souryal, Luke Klein-Berndt, Leonard E. Miller, Nader Moayeri
This paper presents the empirical results and analysis of a link variability study for an indoor, stationary 802.11 network subject to external interference. The objective is to characterize the relationships between the packet loss rate on a link and the

A Measurement-Based Multisine Design Procedure

January 1, 2006
Author(s)
M. Myslinski, Kate Remley, Michael McKinley, Dominique Schreurs, Bart Nauwelaers
This work presents a procedure to design a multisine with probability density function (PDF) similar to that of a measured realistic digitally modulated signal. We discuss important practical issues crucial to the successful multisine construction and

Joint Rate Adaptation and Channel-Adaptive Relaying in 802.11 Ad Hoc Networks

January 1, 2006
Author(s)
Michael R. Souryal, Nader Moayeri
Channel-adaptive relaying has recently been proposed as a means to exploit spatial and temporal diversity in multihop ad hoc networks with fading. In conjunction with appropriate routing protocols, adaptive relaying enables each forwarding node in a

Channel-Adaptive Relaying in Mobile Ad Hoc Networks with Fading

October 1, 2005
Author(s)
Michael R. Souryal, Nader Moayeri
This paper describes an approach for relaying in multihop networks that adapts to the time-varying channel and exploits spatial diversity to mitigate multipath fading. Ignored in some simulation-based performance analyses, fading arises from multipath

Soft Decision Metrics for Turbo-Coded FH M-FSK Ad Hoc Packet Radio Networks

October 1, 2005
Author(s)
B M. Peric, Michael R. Souryal, E G. Larsson, B R. Vojcic
This paper addresses turbo-coded non-coherent FH M-FSK ad hoc networks with a Poisson distribution of interferers where multiple access interference can be modeled as symmetric a-stable (SaS) noise and a is inversely proportional to the path loss exponent

Security Considerations for Voice Over IP Systems

January 1, 2005
Author(s)
David R. Kuhn, Thomas J. Walsh, S G. Fries
Voice over Internet Protocol (VOIP) refers to the transmission of speech across data-style networks. This form of transmission is conceptually superior to conventional circuit switched communication in many ways. However, a plethora of security issues are
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