[MLB-WIRELESS] early morning musings

[Tony Langdon]

> One of the curious aspects of developing this network is the way it 
> forces us into thinking about geography.  How many of us have 
> previously given much thought to the hills and valleys of our local 
> area?  Mostly, I am familiar with Melbourne from the man-made 
> artifacts, the roads and streets, bridges and buildings, which have 
> been constructed over the natural landscapes.  I think my way around 
> the city by the lines on the Melways, not by following a stream or 
> ridgeline.

The latter is a bit more second nature to me, because I've been concerned
about radio propagation for, umm, close to 15 years, maybe longer.  It is a
different way of looking at things, but one that works well when looking at
natural phenomena.  For instance, I already know that the most likely routes
for network access are from the west (across the valley), south (up the
local valley, where I have LOS for several km) or someone within 500 metres
in any other direction (ya can't beat proximity ;) ).

Reminds me of a radio contest we used to run at the club, called "Radio on
Rails".  Basically a 4 hour event, the object being to contact as many
stations as possible in that 4 hour period.  One of the most effective
techniques was to have a sound knowledge of the major natural geographic
features of Melbourne and plan one's train/tram journey around them.  The
other was (of course) having sufficient power and the best antennas you
could safely carry.  I scored a hat trick (won 3 in succession) out of the 4
that I took part in, so I guess I'm qualified to offer some comment. :-)

For instance, being "stranded" at Essendon station for approximately 40
minutes was actually a good thing, as Essendon station is elevated somwhat
above the roadway.  The alternative was to continue on the tram into town -
a 30 minute "RF suicide" trip that leaves one shielded by a ridge from the
main activity, before descending into the valley of the Moonee Ponds creek.
:-)

> But the line-of-site issue forces us to take this landscape into 
> account.  For the first time, many of us are looking up, seeing the 
> hills, following the high ground across town, seeing where it leads 
> us.  Additionally, range issues force us to think about locality, 
> about who and what is around us, and what we might want to say to 
> each other.

Now there's a community building exercise - working with your "RF neighbour"
:-)

> This brings to mind the idea of the "bioregion" 
> <http://www.wri.org/wri/biodiv/bioregio.html>, which is sometimes 
> used in resource management and planning.  A bioregion is loosely 
> defined as a a self-contained ecological and social area.  It's the 
> area around you that you think of as home, and the human society that 
> inhabits it, but also a distinct biological community, with plant and 
> animal communities different from the bioregions around it. 
> Boregions are nested within each other, as "Coburg" is in "Inner 
> North" is in "Melbourne" is in "Victoria"

Similarly, there are "RF precincts" around Melbourne.  Typically, the NE
suburbs are largely cut off from the rest of the city by a ridge near
Greensborough.  The "Western Precinct" where I am is vast, due to the mostly
flat terrain, and the east has lots of little pockets between the main
ridges.  However, these ridges can also serve as natural "interference
barriers" when the node count gets high, by shielding an area from more
distant nodes that can do nothing but increase the noise floor...  Kind of
like a cellular network where the only way in is via the links between
adjacent "cells".

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