Barbeau and Kranakis (2003) have introduced
a novel framework which core is a probabilistic model in which service discovery
strategies can be modeled and evaluated in a uniform manner. They show how
strategies can be represented,
analyzed and evaluated through simulation. Three strategies were initially
studied in detail: post-to-all/query-to-all, uniform memory less and incremental
post-query. The Masters student Luo (2003) has pursued this work and implemented
five strategies (greedy, incremental, uniform memoryless, with memory and
conservative) over two different routing protocols (DSDV and DSR) in the
NS2 simulation environment. The following approach has been devised by the
Ph.D. student Hall to detect the start of the transient in radio frequency
fingerprinting. A stream of samples is decomposed into contiguous
and non overlapping windows of equal lengths. The variance of the phase
for each window. The differences in the variance of the phase are calculated
as well from window to window, i.e. the first derivative of the phase. It
appears that the differences are chaotic, until the start of the transient.
Then at the start of the transient, the differences suddenly fall below
a threshold. In other words, the second derivative of the difference in
variance of the phase almost becomes null. The Masters student Elaasar
(2003) has proposed an error control strategy for the Satellite Transport
Protocol (STP) that makes it more adaptive to the unique error conditions
in satellite access networks. The new strategy is based on an end-to-end
probing mechanism that uses the persistence of the error condition as an
indication to the kind of prevailing error in the network. The mechanism
works by suspending data transmission when an error is detected and investing
some time and transmission effort to sense the current delays in the network.
The mechanism associates error conditions accompanied by noticeable delays
with network congestion.
Otherwise, it associates these errors with different link error events.
Using simulation, it is shown that the new probing mechanism for STP indeed
improves the effective throughput and increases the energy efficiency of the
under various network error conditions. The simulation was carried in PIX
(Protocol Implementation Framework for Linux), a tool developed by our group.
The Masters student Li (2003) has conducted integration testing of XSTP
a file transport protocol and an ad hoc network protocol. Regarding the
ad hoc formation of association groups for secure services and policy distribution
mechanisms, use of a presence-based architecture for managing secure services
has been proposed by the Ph.D. student Ghavam (2002). This work forms the
basis for the development of an enhanced context-based virtual private.