Julia Andrusenko

Wireless network modeling and simulation tools for designers and developers

Modeling and simulation methods are employed by scientists and engineers to gain insight into system behavior that can lead to faster product time-to-market and more robust designs. These advantages come at the cost of model development time and the potential for questionable results because the model represents limited attributes of the actual system. M & S techniques are used to characterize complex interactions and performance at various layers of the protocol stack. This article provides a discussion of M & S for wireless network designers and developers, with particular attention paid to the architectural issues, as well as a discussion of the various communication M & S tools available today. The topics presented span the protocol stack, including radio-frequency-propagation M & S tools, physical-layer and waveform M & S, network-layer M & S, and distributed simulation, as well as waveform generation for test and evaluation.

Military operations in urban terrain: indoor radio frequency propagation prediction methods

This paper investigates the applicability of two current military tactical communications technologies to military operations in urban terrain (MOUT): Single channel ground and airborne radio system (SINCGARS) and squad radios. Various existing radio frequency (RF) propagation prediction (or path loss) methods for urban environments were surveyed. The primary criterion for the selection of methods of consideration was that they must be valid over the 30-88 MHz frequency range of primary interest. Predicted results from chosen analytical tools were compared to measurements taken using a hardware suite representative of SINCGARS on the campus of The Johns Hopkins University Applied Physics Laboratory (JHU/APL) for select indoor propagation scenarios. A new analytical indoor path loss model is derived from measurements by methods of polynomial and power curve fitting for a typical one-story office building. Also, modifications made to chosen analytical models yielded more accurate predictions.

The Effects of Antenna Pointing Error on Bit Error Rate Performance in Mobile Directional Antenna Applications

This paper investigates the issue of antenna pointing error in mobile directional antenna applications and its impact on bit error rate (BER) performance of the link. BER performance is investigated for a variety of postulated antenna characteristics in order to determine the sensitivity of BER performance to antenna pointing inaccuracies. The method employed uses motion dynamics derived from vehicular road course tests to determine power fade profiles for various antenna types as a function of antenna pointing accuracy. These power fade profiles are then used to characterize these channels as Rician multipath channels. Finally antenna pointing accuracy is mapped directly to link BER performance for an uncoded differential phase shift keying (DPSK) waveform. This study has found that this is a complex multi-dimensional problem. Power fades resulting from pointing inaccuracy generally deteriorate for larger antennas with narrow beamwidths. However, smaller antennas are more susceptible to multipath effects due to increased beamwidth. Results of this paper suggests that, contrary to what intuition might initially suggest, larger antennas with more narrow beamwidths may actually outperform smaller antennas in mobile applications

The Wireless Ecosystem

This chapter contains sections titled: Wireless Standardization Process IEEE IETF 3GPP 3GPP2 International Telecommunications Union Wi-Fi Alliance WiMax Forum Bluetooth Special Interest Group ]]>

A hybrid 802.16/802.11 network architecture for a united states coastal area network

This paper presents a concept for a United States Coastal Area Network (U-SCAN) that is comprised of IEEE 802.11, 802.16, and satellite communications technologies. The Office of Naval Research (ONR) on behalf of the National Oceanographic Partnership Program (NOPP) has tasked The Johns Hopkins University Applied Physics Laboratory (JHU/APL) to perform an architectural study into the establishment of a United States Coastal Area Network (U-SCAN). The goal of this study is to define a wireless network architecture that can be deployed to enable contiguous coastal area network coverage for scientific, commercial, and homeland security (e.g. Coast Guard) applications within the United States Exclusive Economic Zone (EEZ), in a manner that is flexible, manageable, and affordable. The JHU/APL study will ultimately provide recommendations to NOPP regarding potential network architectures and technologies that could provide the desired capability, with a particular focus on commercial (both existing and emerging) technologies. This paper presents the envisioned U-SCAN architecture, and presents the envisioned technical capabilities and shortcomings of the component candidate technologies.

Augmentation of Military Satellites with High Altitude Balloons: A UHF Case Study

This paper presents analysis ascertaining obtainable coverage that provides services to ultra-high frequency (UHF) satellite communications (SATCOM) users in the Northern Polar regions through the employment of high-altitude balloons equipped with a UHF capability. This coverage performance is compared to that achieved by the current UHF polar satellite capability. The required capability onboard the balloon is determined, along with the number of balloons required to provide coverage performance equivalent to the current UHF polar satellite capability