Event

Ph.D. Dissertation Defense: John Rzasa

Tuesday, November 27, 2012
12:00 p.m.
Room 2460, AVW Building
Maria Hoo
301 405 3681
mch@umd.edu

ANNOUNCEMENT: Ph.D. Dissertation Defense

Name: John Rzasa

Date: Tuesday, November 27, 2012 at 12 pm

Location: Room 2460, AV Williams Building

Committee:

Professor Christopher C. Davis, Chair

Professor Gilmer L. Blankenship

Professor Thomas E. Murphy

Professor Julius Goldhar

Professor Douglas Currie, Dean's Representative

Title: POINTING, ACQUISITION, AND TRACKING FOR DIRECTIONAL WIRELESS COMMUNICATIONS NETWORKS

Abstract: Directional wireless communications networks (DWNs) are expected to become a workhorse of the military, as they provide great network capacity in hostile areas where omnidirectional RF systems can put their users in harm’s way. These networks will also be able to adapt to new missions, change topologies, use different communications technologies, yet still reliably serve all their terminal users. DWNs also have the potential to greatly expand the capacity of civilian and commercial wireless communications networks. The inherently narrow beams present in these types of systems require a means of steering them, acquiring the links, and tracking to maintain connectivity. This area of technological challenges encompasses all the issues of pointing, acquisition, and tracking (PAT).

The two main technologies for DWNs are Free-Space Optical (FSO) and millimeter wave RF (mmW). FSO offers tremendous bandwidths, long ranges, and uses existing fiber-based technologies. However, it suffers from severe turbulence effects when passing through long (>kms) atmospheric paths, and can be severely affected by obscuration. MmW systems do not suffer from atmospheric effects nearly as much, use much more sensitive coherent receivers, and have wider beam divergences allowing for easier pointing. They do, however, suffer from a lack of available small-sized power amplifiers, complicated RF infrastructure that must be steered with a platform, and the requirement that all acquisition and tracking be done with the data beam, as opposed to FSO which uses a beacon laser for acquisition and a fast steering mirror for tracking.

This thesis analyzes the many considerations required for designing and implementing a FSO PAT system, and extends this work to the rapidly expanding area of mmW DWN systems. Different types of beam acquisition methods are simulated and tested, and the tradeoffs between various design specifications are analyzed and simulated to give insight into how to best implement a transceiver platform.

An experimental test-bed of six FSO platforms is also designed and constructed to test some of these concepts, along with the implementation of a three-node bi-connected network. Finally, experiments are conducted to assess the performance of fixed infrastructure routing hardware when operating with a physically reconfigurable RF network.

Audience: Graduate  Faculty