Jack Unger wrote:
1. The attenuation between 2.4 GHz nodes is not enough to prevent each
node from hearing multiple other nodes as noise (thus more packet
retransmissions and more reduced throughtput). This requires
understanding link budgets, signal-to-noise ratios, and receiver
threshold specifications.
Luckily for us we happen to be a WISP that understands these issues. We
have deployed several Tropos-based networks with sufficient attenuation
between nodes.
2. Metricom is not a good comparison because:
a. They were frequency hoppers on 900 MHz.
Physics applies on all spectrum.
b. They promised low (128kbps and then 256kbps, if memory serves)
throughput. This doesn't compare to today's expected throughput levels.
It was stated that the problems occurred for hams at 1200 baud.
c. They eventually went to a two-band node that backhauled on 2.4 GHz.
so they could increase throughput.
Only in select areas; the vast majority of the network was single band.
d. Metricom then went out of business.
The network did work and it was profitable in a number of cities. The
fact that there was a market bust or that company built more cities than
they had cash flow to support isn't a technical concern.
Physics is still physics and companies need to but don't yet
understand wireless physics. They need this understanding before
bidding on muni projects and before they make these high-expectation,
wireless-for-all, triple-play (voice, video, data) promises to public
officials. Once a muni network is engineered incorrectly and deployed
incorrectly, it may well take as much additional money to fix it (if
it even can be fixed) as it took to deploy it in the first place.
Math is still math and companies need to but don't yet understand
advanced mathematics. This generalization is just as accurate as your
statement, but hopefully seems more absurd. Some companies understand
wireless physics. Some of these same companies even deploy wireless
networks that work. Some markets meet the correct criteria to have a
muni Wi-Fi network that can be successful; some even exist today. How do
any of these statements specify the success of muni Wi-Fi in general?
-Matt
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