How many Google wireless access points for San Francisco?

A bit of math on counting the number of wireless access points
required to cover San Francisco.

The original numbers:
| http://www.outlook4mobility.com/comm...05/oct1205.htm

The revised version:
| http://www.outlook4mobility.com/comm...05/oct1305.htm

--
Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
831.336.2558 voice
http://www.LearnByDestroying.com AE6KS
http://802.11junk.com Skype: JeffLiebermann
(E-Mail Removed) (E-Mail Removed)

Jeff Liebermann wrote:
> A bit of math on counting the number of wireless access points
> required to cover San Francisco.
>
> The original numbers:
> | http://www.outlook4mobility.com/comm...05/oct1205.htm
>
> The revised version:
> | http://www.outlook4mobility.com/comm...05/oct1305.htm
>

The eventual result:

http://www.kcra.com/news/4512146/detail.html

--
Phil Nelson

Jeff Liebermann <(E-Mail Removed)> wrote:

>A bit of math on counting the number of wireless access points
>required to cover San Francisco.

>The original numbers:
>| http://www.outlook4mobility.com/comm...05/oct1205.htm

>The revised version:
>| http://www.outlook4mobility.com/comm...05/oct1305.htm

Lessee. If the inter-access point spacing is D, then the
density is 1/D^2 per unit area. If they are optimally
arrayed in a honeycomb fashion, the maximum distance to a
client is D / (2 * cos(pi/6), or 0.57 * D.

If you want 300 feet to be the maximum distance to a client, then
D = 526 feet, which is pretty close to exactly 0.1 miles,
so yeah. 100 AP's per square mile. The revised calculation
is correct.

But (a) 300 feet is too far for this all to work and (b) you
won't be able to optimally place them so you'll need more.
I'd say 200 per square mile if you want it not to choke,
or 10,000 access points in San Francisco.

Steve

Steve

On Tue, 25 Oct 2005 04:47:46 GMT,
in article <(E-Mail Removed)>,
(E-Mail Removed) (Jeff Liebermann) writes...

> A bit of math on counting the number of wireless access points
> required to cover San Francisco.
>
> The original numbers:
> | http://www.outlook4mobility.com/comm...05/oct1205.htm
>
> The revised version:
> | http://www.outlook4mobility.com/comm...05/oct1305.htm


His skepticism about the whole idea is not a lot different
than my own. Like Seybold, I think interference in the 2.4Ghz
band is going to be a monstrous issue, among other things.

Which is why I was thinking (as posted earlier) that they
should probably consider something like proprietary,
neighborhood-based mesh radios which local users can tap off
of and distribute either via wires or their own WAPs. Just
run a "backbone" and let the end-users install the local radios
so you can wash your hands of the local interference issues.

Then the challenge would be how to interconnect the backbone
to the local segments. Sigh.

<evil grin> I've got it -- Bluetooth! Hehehehe...



--
* Few people are capable of expressing with equanimity opinions which *
* differ from the prejudices of their social environment. Most people are *
* even incapable of forming such opinions. -- Albert Einstein *
* *
* To send email, remove numbers and spaces: pjkusenet64 @ ekahuna27 . com *
* Simple answers are for simple minds. Try a new way of looking at things. *

Philip J. Koenig <See_email_@ddress_below.This_one_is.invalid> wrote:

>His skepticism about the whole idea is not a lot different
>than my own. Like Seybold, I think interference in the 2.4Ghz
>band is going to be a monstrous issue, among other things.

There are 25 unlicensed channels in the 5 GHz band. I assume they
will deploy there -- otherwise, it is completely hopeless.

What I don't know is whether Google has an actual engineering
team on this or whether it's still just in marketing.

Steve

On Tue, 25 Oct 2005 09:53:49 +0000 (UTC),
in article <djkvbd$s4a$(E-Mail Removed)>,
(E-Mail Removed) (Steve Pope) writes...
> Philip J. Koenig <See_email_@ddress_below.This_one_is.invalid> wrote:
>
> >His skepticism about the whole idea is not a lot different
> >than my own. Like Seybold, I think interference in the 2.4Ghz
> >band is going to be a monstrous issue, among other things.
>
> There are 25 unlicensed channels in the 5 GHz band. I assume they
> will deploy there -- otherwise, it is completely hopeless.


What's the point of putting radios in 5Ghz spectrum when almost
no users are going to be able to receive those signals directly?

Telling everyone to go buy 802.11a hardware is going to be
a non-starter.



> What I don't know is whether Google has an actual engineering
> team on this or whether it's still just in marketing.


As I posted a few days ago, for the SF bid Google is partnering
with a San Diego-based wireless engineering company which, among
other things, will be involved in building a muni wifi system in
Madison Wisconsin.

This is the partner:
http://www.wfinet.com/index.html



--
* Few people are capable of expressing with equanimity opinions which *
* differ from the prejudices of their social environment. Most people are *
* even incapable of forming such opinions. -- Albert Einstein *
* *
* To send email, remove numbers and spaces: pjkusenet64 @ ekahuna27 . com *
* Simple answers are for simple minds. Try a new way of looking at things. *

Philip J. Koenig wrote:
> On Tue, 25 Oct 2005 09:53:49 +0000 (UTC),
> in article <djkvbd$s4a$(E-Mail Removed)>,
> (E-Mail Removed) (Steve Pope) writes...
>
>>Philip J. Koenig <See_email_@ddress_below.This_one_is.invalid> wrote:
>>
>>
>>>His skepticism about the whole idea is not a lot different
>>>than my own. Like Seybold, I think interference in the 2.4Ghz
>>>band is going to be a monstrous issue, among other things.
>>
>>There are 25 unlicensed channels in the 5 GHz band. I assume they
>>will deploy there -- otherwise, it is completely hopeless.
>
>
>
> What's the point of putting radios in 5Ghz spectrum when almost
> no users are going to be able to receive those signals directly?
>
> Telling everyone to go buy 802.11a hardware is going to be
> a non-starter.


Possibly, but a lot of technology is driven that way. 5 GHz hardware is
not common and expensive because everyone piled into the 2.4 GHz band.
If they chose for SFO the 5 GHz band they would free themselves from the
current issues and the 5 GHz equipment would become just as common and
inexpensive.



>
>
>
>
>>What I don't know is whether Google has an actual engineering
>>team on this or whether it's still just in marketing.
>
>
>
> As I posted a few days ago, for the SF bid Google is partnering
> with a San Diego-based wireless engineering company which, among
> other things, will be involved in building a muni wifi system in
> Madison Wisconsin.
>
> This is the partner:
> http://www.wfinet.com/index.html
>
>
>

George <(E-Mail Removed)> wrote:

>Philip J. Koenig wrote:

>> (E-Mail Removed) (Steve Pope) writes...

>>>There are 25 unlicensed channels in the 5 GHz band. I assume they
>>>will deploy there -- otherwise, it is completely hopeless.

>> What's the point of putting radios in 5Ghz spectrum when almost
>> no users are going to be able to receive those signals directly?

>> Telling everyone to go buy 802.11a hardware is going to be
>> a non-starter.

>Possibly, but a lot of technology is driven that way. 5 GHz hardware is
>not common and expensive because everyone piled into the 2.4 GHz band.
>If they chose for SFO the 5 GHz band they would free themselves from the
>current issues and the 5 GHz equipment would become just as common and
>inexpensive.

Adoption of 5 GHz is a lot slower than many in the industry
predicted, but it will soon be pretty standard. For those
with older 2.4 GHz-only devices, they will just have less
coverage -- much as having a single-band cellphone (if there
is such a thing now) has less coverage.

Steve

On Tue, 25 Oct 2005 07:40:35 -0400, George <(E-Mail Removed)>
wrote:

>Possibly, but a lot of technology is driven that way. 5 GHz hardware is
>not common and expensive because everyone piled into the 2.4 GHz band.
>If they chose for SFO the 5 GHz band they would free themselves from the
>current issues and the 5 GHz equipment would become just as common and
>inexpensive.

Not common? 5.7GHz is where all the wireless backhauls are currently
located.
http://www.wbanc.com
If SF decided to go with 5.7GHz 802.11a clients, then I'm sure the
market would gladly support replaceing everything you own with the
latest and greatest. (Evolution. Upgrade or die). However,
relocating the backhauls to 22Ghz may be a bit of a challenge.
considering the mesh network rule of thumb of the week of no more than
3-4 hops from client to backhaul, and 100 access points per square
mile, that means 25-33 backhaul radios or wired connections per square
mile.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann <(E-Mail Removed)> wrote:

>Not common? 5.7GHz is where all the wireless backhauls are currently
>located.
> http://www.wbanc.com
>If SF decided to go with 5.7GHz 802.11a clients, then I'm sure the
>market would gladly support replaceing everything you own with the
>latest and greatest. (Evolution. Upgrade or die). However,
>relocating the backhauls to 22Ghz may be a bit of a challenge.

You mean 24 GHz I think.

>considering the mesh network rule of thumb of the week of no more than
>3-4 hops from client to backhaul, and 100 access points per square
>mile, that means 25-33 backhaul radios or wired connections per square
>mile.

Despite their fumbling, Google definitely has the money to
deploy that hardware this project requires. Google's only limit
is the laws of physics.

S.