[e2e] Simulator for wireless network
detlef.bosau at web.de
Sun Apr 15 12:15:14 PDT 2007
Adam Wolisz wrote:
>> Giuseppe has addressed a very important point.
>> In fact the following question is a basic one: what is to be
>> investigated - an ideal behavior of the envisioned,
>> precisely defined solution - or THE behavior of really deployed
Exactly. And that´s why it´s so important to have the question well put.
And when we investigate the behaviour of a deployed product, we
practically investigate the behaviour of _exactly_ _that_ deployed
product - which may well be subject to change without notice (as it is
written in nearly each manual of any appliance you can buy). Standard
violation included, as you wrote later in your post.
>> In the WINTECH 2006 workshop The First ACM International Workshop on
>> Wireless Network Testbeds, Experimental evaluation and
>> CHaracterization - one of the MOBICOM 2006 workshops -
>> a very interesting paper presents
>> "An Empirical ANalysis of Heterogeneity in IEEE 802.11 MAC protocol
>> implementations and it implications"
>> Surprisingly enough, besides of a long list of differences which are
>> to be expected _ e.g. rate adaptation
>> algorithms are NOT defined by the standard, propreitary solutions
>> have to be used! - also
>> very clear violations of the standard have been observed within
>> products of major manufactureres.
>> In particular the list of observed differences (and violations of the
>> standard!) has been given,
>> along with a demonstration, that due to this differences unfairness
>> in bandwidth sharing exists among terminals
>> using products of different manufactures. And the differences ARE
One important question is always the objective of a simulation:
- Are we interested in whether a proposed mechanism / standard works
fine? Then we should so state and then the question is a structural one
and not a technological one. To my understanding, this is basically the
- Are we interested in whether a certain appliance / device /
implementation complies to a standard, or whether a proposed standard is
beyond actual technological limitations, then the question is a
technological one. That´s bascially the development perspective.
Technological limitations can well influence the standards, IIRC a
prominent example is the inter frame gap in Ethernet which was due to
the fact that early Ethernat adapters could not switch faster from the
transmission mode to the receiver mode.
Mail: detlef.bosau at web.de
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