[olug] Cox sucks
Sam Tetherow
tetherow at shwisp.net
Tue Jul 17 21:33:00 UTC 2007
Benjamin Watson wrote:
> <SNIP>
>
>
> On a final note, part of my thesis project is dealing with wireless
> mesh networks. Some articles/blogs 'round the 'net give a lot of
> readers a bad taste when it comes to city-wide wireless Internet
> access. However, I think it is a novel concept which is gaining more
> popularity. I think Salt Lake City and a few other markets have
> sponsored free wireless Internet access throughout their cities with
> decent results and user satisfaction (I mean, its free, right). My
> research and testing shows that it is possible to stand up a wireless
> Internet network blanketing a fair part of Omaha, but the problem is
> access to an Internet backbone. Grass routes efforts in other cities
> are possible, where "regular people" stand up their own nodes and
> share their bandwidth. But in COX-town, I'd bet that wouldn't jive
> with their ToS. I wonder if Level3 wouldn't mind lighting up some of
> the dark fiber they've got laying around all over for such an effort.
>
> Ben
>
>
This is going to be a bit long winded....
I have seen very few articles that report success for city wide wireless
internet access, unless they are press releases from whoever is
intimately involved with those networks. Both Earthlink and MetroFi
announced that they are reviewing their business models and Earthlink
has put on hold all new buildouts at this time.
There are several problems with municipal level wireless, by this I mean
city wide not municipal funded.
Cost is one major factor, the current rule of thumb is between $200,000
and $300,000 per square mile for capex and opex is estimated at 30%
capex annually. This number is for infrastructure only and using these
estimates you are still only reaching approximately 90% of all homes, of
which only 10-15% can reliably connect without either an external or
high powered CPE which will cost between $100-200.
The next issue in a muni network is going to be available spectrum. It
is going to be sharing 2.4GHz with every cordless phone, baby monitor,
wireless entertainment center, security camera, microwave oven and home
wifi router. If you move outside of 2.4GHz you will increase your
infrastructure cost as well as requiring a CPE in 100% of all installs
since laptops come with 2.4GHz standard all other frequencies require a
seperate card.
Next is the issue of bandwidth. Outdoor 802.11g has enjoyed very little
success due to timing, power and sensitivity issues. In a best case
scenario you are looking at 19Mbps optimal 802.11g throughput (at 54Mbps
air rate) assuming a clean connection and 4Mbps optimal 802.11b
throughput (at 11Mbps air rate), but given the nature of the network.
You will most likely see suboptimal connections due to people who can
only connect at a lower data rate either because the fall just above the
10% who can't be served or they fall in the 75-80% who really should
have an external CPE but can connect marginally without it. Each user
operating at suboptimal speed will effect every other user on that AP.
If you abandon 802.11x for a proprietary protocol to address poor
spectral efficiency you will increase the cost as noted above by
requiring users to purchase external devices to connect to the network
and you will still be limited by the theoretical 6bps/Hz maximum. In
2.4GHz that gets you 60*6=360Mbps theoretical maximum air rate across
the entire band which will give you about 150Mbps total optimum
throughput. You still have to deal with the effects of interference and
poor connection quality though, which will significantly reduce this
number. You can get access to another 60MHz of spectrum in the 5.8 ISM
band but your propagation characteristics reduce further. There is also
the possibility of even lower powered use of the 5GHz UNII band which is
265MHz but it is saddled with the new DFS requirement and as far as I
know only one manufacturer has managed to get equipment through FCC testing.
Topology issues would be next on the list as you mentioned mesh which
usually implies connecting multiple APs wirelessly for backhaul so you
further reduce your available bandwidth. Optimal would be a fully routed
network which would mean that data only flows through nodes that it has
to flow through, but this would negate roaming the mesh. If you allow
roaming then you can effectively halve the available bandwidth for each
node wirelessly linked together.
I apologize for the length of this message but there are a lot of issues
surrounding municipal level wireless networks and why they are such a
challenge to implement.
The only practical use I could see for a municipal level wireless
network would be for the casual user so they can read email and lightly
browse the web, but at $200-300K/sq mi upfront and $40-60K/sq mi annual
recurring that is pretty costly. Once you get past the casual user, the
network will not scale to handle the ever increasing bandwidth usage of
the home user.
Sam Tetherow
Sandhills Wireless
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