Subject: Re: [manet] Ad-hoc networking arrives?

From: Abdussalam Baryun <[email-masked]>
Date: Wed, 16 Feb 2011 16:33:52 +0000

Yes, I agree, the protocol looks similar to 802.11s, but it does not use
multi-hop communication, without routing, and it is using smart antennas for
the destination discovery. However, I agree that it is not clear yet, but it
does not seem as a power efficient system, if it will cover to distance
above 500m.

Abdussalam

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From: Tim Shepard <[email-masked]>
Date: Thu, 17 Feb 2011 12:22:47 -0500

> does not seem as a power efficient system, if it will cover to distance

Compared to what?  Multihop?  But multihop requires the deployment of
intermediate nodes. If I'm here and you're there and we're going to
want to communicate using this scheme and we want it to be multihop to
improve its energy efficiency, then we would also have to somehow
arrange for the deployment of intermediate nodes (which is not likely
to happen).  There doesn't seem to be much point in having multihop in
this context.

The energy saving gains from multihop are the same kind of gain you
get from directionality.  Omni antennas with a single ideally placed
intermediate node saves you half the power (1/4 power on each of two
transmissions, 1/4 times 2 is 1/2).  You could also save half the
power with a measely 3 dB of combined antenna gain at sender and
receiver (e.g. could be 1.5 dB at the sender plus 1.5 dB at the
receiver).  If you look at system performance gain vs the increased
system complexity costs for for both (1) multihop and (2) increased
gain from directional antennas, it seems that in most likely scenarios
you get a better payoff by putting the effort into antenna gain.  And
the antenna gain also lets you do things you otherwise would not be
able to do when there are no intermediate nodes.

Yes, you can do both.  But if you were getting started and cannot do
everything in version 1.0 and want to decide which to do first,
directional gain from better antennas wins over multihop, and it is
not even close.

			-Tim Shepard
			 [email-masked]