Satellite Communications Engineer Expert Witness

Expert Witness No. 121

New Jersey

Network Architecture, Design & Analysis Performance Analysis Broadband Wireless Satellite Networks

Professional Experience

A. T. Kearney, January 99 - Present

DLT Consultant, London, England 

Participate on the second phase of a technical due diligence team assessing the satellite and ground systems for a global mobile satellite system.

Quantify launch failure scenarios. AT&T Laboratories, October 98 – December 98

DLT Consultant, Holmdel, NJ

Define Internet and Intranet measurement methodologies to assess end-user perceived performance. Software Technologies, Inc., June 98 - Present

DLT Consultant, Melbourne, FL 

Perform scalability analysis of the system design for a ground station satellite controller. Motorola Satellite Communications, June 98 - July 98

IQ Tech Consultant, Chandler, AZ

Began performance assessment of access schemes for data services for a next generation mobile satellite system A. T. Kearney,January 98 - March 98

IQ Tech Consultant, London, England

Participate on a technical due diligence team assessing the satellite and ground systems for a global mobile satellite system.

Assess cost models used in the Satellite System Business Plan.

Quantify launch failure scenarios. Bell Communications Research, September 97 - December 97

IQ Tech Consultant, Morristown, NJ

Provide algorithms and custom software for approximating long-range dependent data traffic (e.g., IP or broadband) with a Markovian Arrival Process.

Provide algorithms and custom software for computing appropriate performance measures to be used for engineering the network. Lockheed Martin Telecommunications, September 96- August 97

IQ Tech Consultant, Sunnyvale, CA

General performance analysis for the Astrolink broadband satellite system.

Assessed the loss of efficiency of imposing various constraints on the Demand Assignment Multiple Access (DAMA) algorithms.

Buffer sizing studies. AT&T Laboratories, September 96 - April 97

IQ Tech Consultant, Holmdel, NJ 

Began assessment of internet telephony as both a threat and an opportunity to AT&T longdistance revenues.

Prepared an internal management presentation on Choices in Packet Telephony. AirNet Communications, Inc., June 95 - June 96

IQ Tech Consultant, Melbourne, FL 

Provide continuing consulting services for performance analysis and architecture for a start-up wireless company.

Supervised in-house development of a system-level simulation.

Designed the resource allocation algorithm for a PCS1900 Base Station Subsystem.

IQ Tech staff completed development of the call processing (architecture design, implementation and testing) of a PCS1900 Base Station Controller in 15 months.

Presented the paper "Supporting ATM on Low-Earth Orbit Satellite Systems" at the ITC Specialists Seminar in Amsterdam. Motorola, Inc., Sept. 94 - June 95

IQ Tech Consultant, Chandler, AZ
General performance analysis for the Iridium™ Low-Earth Orbit satellite system.

Continued development of a crucial resource allocation algorithm which operates in real time on-board the satellite vehicle.

Developed risk models to determine insurance strategies for coping with potentially unreliable launch vehicles in the initial deployment of the Iridium™ system.

Recruited and established a Network Integrity Support Team to focus on performance aspects of the Iridium™ system. Motorola, Inc., April-Sept. 1994

Member of Technical Staff (GS-13),Chandler, AZ

General performance analysis for the Iridium™ Low-Earth Orbit satellite system.

Designed a real-time resource allocation algorithm to operate on-board the satellite vehicle. This algorithm avoided a costly hardware redesign saving more than $30M. AT&T Bell Laboratories,1981-1994

Distinguished Member of Technical Staff, Holmdel, NJ

Broadband ISDN/ATM

defined overall control architecture, incorporating end-to-end flow control, traffic shaping capabilities and higher layer control functions; portions have been incorporated into international standards

using exact and approximate models, quantified the multiplexing gain for a large number of bursty sources and the impact on engineering of ATM networks

using exact models, demonstrated that predictions based on the popular notions of "effective bandwidth" could be arbitrarily poor; proposed more accurate approximations

derived and solved analytically tractable models for quantifying the effectiveness of the "throughput-burstiness filter" and selective cell discard mechanisms for congestion control

using models and analysis, formulated specific recommendations for switched virtual circuit call acceptance/denial algorithms and for bandwidth-on-demand negotiation algorithm

Algorithmic solutions to stochastic models, queuing theory, and applied probability

developed algorithms for numerically computing an arbitrary number of moments as well as the exact asymptotic behavior of a distribution function from its transform

contributed to the development of algorithms for numerically inverting multidimensional Laplace-Stieltjes transforms and/or probability generating functions

drastically simplified analysis and algorithms for a large class of complex queuing models (BMAP/G/1queue) which also include multiplexed, highly-correlated arrival streams

derived exact solutions and numerical algorithms for computing the transient performance measures of the above class of models; this framework allows new insights into the problems of overload control and call acceptance algorithms for broadband networks

combined transform/eigen-analysis approach with the matrix-geometric method to solve important class of voice and data queuing models

introduced the, now popular, Markovian Arrival Process (MAP) as a versatile and tractable class which includes both renewal and non-renewal point processes

solved the queue with vacations using above model; generalized known factorization results to the non-renewal case and obtained new factorization results

derived an enormously improved approach for solving the nonlinear matrix functional equation arising in the matrix analytic solution to phase-type queues

provided the first general proof that the key transform matrix involved in solving stochastic models of the "M/G/1 Type" was the unique minimal solution to a non-linear matrix- functional equation

Variable-bit-rate video

developed Markov renewal model for sizing leaky bucket parameters for call setup algorithms

defined two novel measures of goodness-of-fit of model to data

Packetized voice and data

derived powerful, and widely used, methodology for approximating superpositions of complicated arrival stream (such as packetized voice) by simpler, tractable processes (e.g., Markov modulated Poisson processes)

derived analytic model of bit-dropping in packetized voice which demonstrated (and explained why) a Poisson process was an accurate model for predicting performance

Wideband packet technology

derived and solved (using state-of-the-art solution techniques) an analytic model of the LAPD protocol incorporating timers, retransmissions, polls, etc., in conjunction with a variety of end-terminal window adaptation procedures and network throughput enforcement controls

LAPD frame relay

assisted in design of terminal adapters for frame-relay networks by identifying performance degradations resulting from interactions of pipelining and protocol windowing

Packet switching

derived matrix-analytic performance assessment methodology for a synchronous self-routing packet switching fabric which quantified impact of traffic burstiness and effects of switch parameters

Digital switch performance

responsible for performance of new modules required to support ISDN on existing digital switches

provided developers with a variety of performance inputs which affected microprocessor selections, buffer sizing, capacity planning, etc.

Cellular phone technology

designed and analyzed a system level overload control; potential system throughput degradation under overload was identified; proposed a simple fix which was implemented in system

Education

Ph.D. Operations Research, University of Delaware, Newark, DE, 1981 

Dissertation analyzed stop-and-wait retransmission protocol for data integrity where the error environment is highly correlated; was published as a monograph in the Research Notes in Mathematics series of Pitman Books Limited, London, 1982

Dissertation contained the first general proof that the key transform matrix involved in solving stochastic models of the "M/G/1 Type" was the unique minimal solution to a non-linear matrix functional equation

Completed over 80 graduate credits in Mathematics and Operations Research with a GPA of 3.96/4.0 M.S. Statistics, University of Delaware, Newark, DE, 1978

Thesis entitled Numerical Methods for a Wide Class of Markov Chains Arising in Queuing Theory B.S. Mathematics, Towson State University, Towson, MD, 1976

Awards and Honors

Mary Hudson Scarborough Award for Excellence in Mathematics, Towson State University, 1976

Allan P. Colburn Prize for best dissertation in Engineering and Mathematical Sciences, University of Delaware, 1982

Subject of biographical record in Who’s Who in Frontier Science and Technology, and American Men and Women in Science, 1984

Co-recipient of IEEE Communications Society Stephen O. Rice Prize Paper Award in the field of Communication Theory (with H. Heffes), 1986

Promoted to Distinguished Member of Technical Staff, AT&T Bell Laboratories, 1987

Co-recipient of an Honorable Mention for the 1998 INFORMS Frederick W. Lanchester Prize for the best published work in Operations Research and the Management Sciences, 1998

Teaching Experience

Stevens Institute of Technology, 1991-93

Adjunct Professor, Computer Science, Hoboken, NJ 

Taught graduate level courses in Probability and Stochastic Processes Patents

Novel congestion control techniques for Broadband ISDN/ATM involving traffic monitoring and tagging as well as selective cell discard during congestion resulted in two patent awards (with A.E.Eckberg, D.T. Luan, and T.J. Schonfeld).

The ideas behind these patents have been incorporated into the international standards for ATM switches.

The patents are now the property of Lucent Technologies.

Professional Activities

over fifty papers published in scientific journals

former Associate Editor for Queuing Systems

reviewer for National Science Foundation proposals and many scientific journals

frequent speaker at international conferences and universities

Member of IEEE, INFORMS, ACM

Publications

List of over 50 Available upon request