Sunday, August 20, 2006

Testing the Google WiFi network using Skype in the car

I drove around Mtn View earlier today to test how well the Google WiFi network worked for mobile users.

For mobile users, the WiFi network is very impressive, imho. Even with a very low-power WiFi card on my laptop, the connection was impressive. Trees seem to attenuate the signals considerably. If I could see a Google node, I could connect to it. If I didn't see the node, the connection was weak.

Google should not use the MAC address to authenticate users - that sounds a little bit extreme.

Test setup
* I hooked up my laptop to the Google WiFi network using an old Cisco Aironet 350 802.11b card.
* I used SkypeOut to call my home phone #.
* The laptop and I both stayed in the car.

The drive
* I drove a little bit on the West side of El Camino Real (around Castro Street), but mostly on El Camino Real and on the East side of El Camino on Castro Street, Shoreline Blvd, Rengstorff Avenues and streets perpendicular to those. I also drove on Central Expressway between Rengstorff Ave. and Castro St.
* I stayed close to areas where the mesh nodes have been installed and did not venture into areas where the Google network is not yet established.

Observations
* Good connection: The connection was very good in the vicinity of the network nodes/access points and also fairly continuous on streets where there were sufficient street lights and network nodes and few trees. I could talk uninterrupted via Skype in these areas.
* Trees problematic: Even when the node density was high, if the street was tree-lined, the voice packets would not go through, though the connection would not drop.
* Works at 35mph: I drove at up to 35 mph speed and the connection wasn't significantly different at that speed compared to slower speeds.
* MAC address authentication?: I authenticated myself via the browser the first time I got on to the network (gave my gmail id). Thereafter, it would let me on to the network even if I removed all the cookies and restarted my computer. It seems that Google is using the MAC address of the WiFi card to authenticate me on to the network.
* Central Expressway: The connection was poor along the Central Expressway since it has few light poles and many trees. The node density is not very high along Central Expressway (http://wifi.google.com/city/mv/apmap.html).

Comparison with other municipal WiFi networks
* Corpus Christi, TX: I have used the WiFi network in Corpus Christi, TX (also set up by Tropos Networks, the same company that provided equipment for Mtn View). I tested the Corpus Chrsti network last year and found it to be much spottier than the Mtn View network. Looks like Tropos is using newer equipment and has tuned the Mtn View network much better.
* Palo Alto, CA: Firetide is setting up a WiFi mesh network for public safety purposes in 2 sq miles of Palo Alto around California Ave. The Firetide network is still being installed and tuned. So far, the Mtn View network performs slightly better than the Firetide network.

Next steps
* I will test with a higher powered (200 mW) WiFi card and a higher gain antenna tomorrow. My guess is that the trees won't be an issue with that type of a setup. Watch this space.

Conclusions
* WiFi networks are tough to set up and maintain.
* You need a little extra power and better antennas, but you can do lots of cool mobile applications in a properly tuned WiFi network.
* The Mtn View Google WiFi network is well-tuned and one of the best when it comes to municipal WiFi networks.

Link
Comments:
Pretty awesome report. Very comprehensive of you.

It worked for me, even at Shoreline park. Granted it's closer to Google's headquarters than Castro is, but I really didn't expect it to be turned on in the park. Geeks know no limits! (And what was I doing there? I only happened to have my laptop with me, so I had to give it a try!)
 
Cooool.
 
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