Multi-Variate Adaptive Protocols for Optimal Communications Efficiency


Outline of Research

Many data communications protocols allow variation of certain
properties, such as frame length, to adapt the performance
to a changing (non-stationary) communications environment. 
However, this is often a one-time setup (stationary) and any 
changes of the environment lead eventually to a degraded 
performance, if not to a total communications failure. Some 
research results are available for the case where the frame 
length is adapted to the measured error rate to achieve a 
rudimentary single-variate adaptation method for simple 
stop-wait (idle RQ) protocols.
   Our research focuses on general adaptation possibilities
of existing protocols to the communications environment
(what to adapt ?). Rather than simple stop-wait protocols, 
more common sliding-windowing protocols are considerd which 
allow for a multi-variate adaptation of several protocol 
attributes, such as frame length, group size, window size 
(also number of windows for multi-window type protocols), 
and retransmission mechanism. 
   A strategy of adaptation is to be developed so that the 
protocol varies its attributes to give the best performance 
with changing environments subject to a stability criterion.  
The conditions to use as adaptation criteria are to be 
determined (when to adapt ?), and the best combination of 
adaptable protocol attributes (what to adapt ?), and adaptation 
algorithms (how to adapt ?) are to be found. 
   First, a simple analytical model is to be developed which 
can beneficially be used to gain insight into the complexity 
of multi-variate adapation, and hopefully leads to a conceptual 
guideline for the best performance optimization approach.
   Subsequently, the adaptive protocols are to be simulated 
in a software testbed for validation purposes. This allows the 
testing of the selected procedures by simulative, yet practical 
experiments. The performance measures appropriate for the 
adaptive process (e.g. throughput, channel utilization, 
adaptation speed, stability, optimality) are to be measured.

   Participating in the research are Dr. Bernd J. Kurz (professor, 
CS at UNB), Dr. Larry Hughes (professor, St. Mary's Univ., Halifax)  
with the assistance of MCS graduate student Manvinder Singh.

Project Status: Started:   May 1997
                Completed: May 1999

Relevant Publications

"Multi-Variate Adaptive Protocols for Data Communications by Manvinder Singh, 
MCS thesis, Faculty of Computer Science, University of New Brunswick, May 1999


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Last revised: 11 March 2004 by Bernd Kurz bjkurz@unb.ca