WiFi (aka 802.11) is a standard used to establish 2 way data transmission using the client/server paradigm. The Access Point (AP) is the server (i.e. the equipment mounted on the light poles) and your laptop/smartphone, etc. is the client.

SVUnwired uses the 802.11b/g standard for client access around the City.

The nodes (wireless routers) of a citywide WiFi network are typically mounted on the light poles around a city for 2 main reasons: 1) The poles are tall (25 to 40 feet high) so the signal has greater reach and 2) they have constant power.

Being so high puts them farther away from the client devices (laptops, smartphones, etc), but the nodes transmit effectively at 4 watts of power -- the maximum amount allowed by the FCC -- which is a much higher level than the normal consumer wireless router. For comparison sake, the average FM radio station transmits at 50,000 watts of power.

A WiFi data connection actually consists of 2 separate, but correlated connections: one from the node down to the client device and a second from the client device back up to the node. For an in-home or in-building network, the distance between the node and client device is usually so short that effectively the transmit power level doesn't matter. However, on the scale of a citywide network, the transmit power levels do make a difference.

To preserve battery life, the typical laptop or smartphone transmits at 40 to 60 milliWatts which is some 80 times less than the node up on the street light.

This means for a WiFi data connection, the first connection -- from the node to the client -- is usually pretty strong, but the second connection -- from the client device back up to the node -- is usually not. That is why when you open your laptop inside your house you typically see good (4 or 5 bars) signal strength, but possibly the network is slow or even doesn't connect at all. The culprit is that second connection -- and the weak transmit power from the client.

So what to do. The trick is to boost the transmit power level for the second connection -- from the client device to the node. One of the best ways to do this is through a device we call a WiFi modem -- also called a CPE device. These devices translate between a WiFi signal and standard ethernet. Since they plug into a wall outlet, power is not a problem and so they typically transmit at between 200 and 600 milliwatts of power -- usually more than enough to reach the node.

SVUnwired does not sell these wifi modems, but you can find them easily on the web. A typical price is between $70 and $100. Here are 3 devices which we have tested and which work well on our network:

• PepWave
• Ruckus
• Engenius

This should give you a pretty good understanding of some of the issues with citywide WiFi networks and some of the solutions used to solve these issues.