NASA Scientific and Technical Aerospace Reports

performance. Following the user profile establishment, individual user training on two specific words reduces error rates
significantly.
DTIC
Computer Programs; Ships; Speech Recognition
20040073551 Naval Postgraduate School, Monterey, CA
Reed-Muller Codes in Error Correction in Wireless Adhoc Networks
Tezeren, Serdar U.; Mar. 2004; 153 pp.; In English; Original contains color illustrations
Report No.(s): AD-A422336; No Copyright; Avail: CASI; A08, Hardcopy
The IEEE 802,11a standard uses a coded orthogonal frequency division multi-plexing (COFDM) scheme in the 5-GHz
band to support data rates up to 54 Mbps The COFDM was chosen because of its robustness to multipath fading affects, In
the standard, convolutional codes are used for error connection, This thesis examines the performance of the COFDM system
with variable rate Reed-Muller (RM) error correction codes with a goal to reduce the peak-to-average power ratio (PAPR),
Contrary to the expectations, RM codes did not provide expected improvement in PAPR reduction, Peak clipping and Hanning
windowing techniques were investigated in order to reduce the PAPR, The results indicate that a tradeoff exists between the
PAPR and the bit-error rate (PER) performance. Although peak clipping yielded considerable reduction in PAPR, it required
high signal-to-noise ratios, On the other hand, Hanning windowing provided only a small reduction in PAPR with reasonable
PER performance.
DTIC
Error Analysis; Error Correcting Codes; Multipath Transmission; Signal to Noise Ratios
20040073557 Naval Postgraduate School, Monterey, CA
Performance Analysis of the Effect of Pulsed-Noise Interference on WLAN signals Transmitted Over a Nakagami
Fading Channel
Tsoumanis, Andreas; Mar. 2004; 87 pp.; In English; Original contains color illustrations
Report No.(s): AD-A422351; No Copyright; Avail: CASI; A05, Hardcopy
This thesis examines the performance of wireless local area network (WLAN) signals, specifically, the signal of IEEE
802,1 la standard, The signal is subject to pulsed noise jamming, when either the desired signal alone or the desired signal
and the jamming signal are subject to Nakagami fading, As expected, the implementation of forward error correction (FEC)
coding with soft decision decoding (SDD) and maximum- likelihood detection improves performance as compared to uncoded
signals, In addition, the combination of maximum- likelihood detection and error connection coding renders pulsed-noise
jamming ineffective as compared to bandage noise jamming, When the jamming signal encounters fading as well, we assume
that the average jamming power is much greater than the AWGN power, For uncoded signals, a jamming signal that
experiences fading actually improves performance when the parameter of the information signal m(s) is less than or equal to
one, Surprisingly, for larger values of m(s) a jamming signal that experiences fading works in favor of the information signal
only for small signal-to- interference ratio (SIR), When SIR is large, performance when the jamming signal experiences fading
is worse relative to performance when the jamming signal does not experience fading, For error correction coding with SDD,
we investigate only continuous jamming since it is by far the worst-case, Moreover, while we consider a range of fading
conditions for the jamming signal, we examine only Rayleigh fading of the information signal, The coded signal, when the
jamming signal experiences severe fading, performs better relative to the case when the jamming signal does not experience
fading,
DTIC
Electromagnetic Radiation; Error Correcting Codes; Fading; Jamming; Reliability Analysis; Signal to Noise Ratios;
Transmitters
20040073566 Naval Postgraduate School, Monterey, CA
Using Agent-Based Modeling to Examine the Logistical Chain of the Seabase
Milton, Rebecca M.; Mar. 2004; 90 pp.; In English; Original contains color illustrations
Report No.(s): AD-A422379; No Copyright; Avail: CASI; A05, Hardcopy
This thesis examines a 2015 Marine Expeditionary Brigade scheme of maneuver as the baseline scenario for a commercial
logistics support software program called SEAWAY, Modifications to this scenario are conducted using a designed experiment
in order to explore how the plan characteristics relate to eleven specified input factors, Multiple regression analysis is used
to fit models to the resulting data for three different measures of performance: Total Aircraft Sorties, Total Aircraft Sortie Time
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