**Municipal WiFi**

[Parinaz_M]

Wireless Basics

The early days of home Internet access required using a modem connected to a computer to dial a number and maintain a connection. It was cumbersome and slow. The faster modems became, the more people realized how painfully sluggish data transmission had been in the days of 300 baud. Eventually, home users who could afford a jump in price could get broadband access via DSL, cable and satellite.
Broadband access is faster than dial-up, but until recently you still to plug your computer into a wall jack or a piece of equipment. Wireless networking, or WiFi has changed all that. Wireless networks use 802.11 networking standards to allow devices to communicate. In a WiFi network, data travels from place to place via radio waves. You still have to physically connect a wireless router to a modem, but you can move your computer from place to place.

802.11 networking uses the unlicensed radio spectrum to send and receive data. Many other parts of the spectrum, such as the bands that carry radio and TV signals, require a license to use. The unlicensed spectrum is accessible to anyone who has the right equipment. In the case of wireless computer networking, that's a wireless router and wireless technology in the device you're using.

Since 2002, many people have set up wireless networks in their homes. Businesses have done the same, giving their employees additional mobility. Public gathering places, like coffee shops, parks and libraries, have created WiFi hot spots, hoping to draw in additional businesses. The number of public hot spots has grown rapidly -- analysts estimate that there will be 200,000 of them by 2008.

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Technology and Networks


Mesh
Most WiFi hot spots in coffee shops and other locations have a hub and spoke configuration. One radio (the hub) sends and receives data for several users (the spokes). The wireless router has a physical connection to the Internet -- a wire -- and it transmits data from multiple users through that wire.

Adding a wireless router to an existing wired connection is an easy, convenient way to provide wireless access on a small scale. Wireless routers are relatively inexpensive. Most allow people to choose from various sign-on and encryption options, providing a layer of security.

But if a wireless router goes down, there's not always another router nearby to pick up the slack. And on a large scale, like a whole city, using a physical wire to connect every wireless router to the Internet is expensive.

That's why most municipal wireless networks use a mesh rather than a hub and spoke. A mesh is a series of radio transmitters. Each transmitter is able to communicate with at least two others. They create a cloud of radio signals through the city. Signals travel from router to router through this cloud.

In some networks, signals hop from one receiver to another until they reach a node that has a wired connection to the Internet. Other networks use backhaul nodes. These nodes do exactly what their name implies -- they gather up all the data from many transmitters and haul it back to the Internet by sending it to a router with a wired connection. Backhaul nodes are usually point-to-point or point-to-multipoint nodes. They can either connect one point to exactly one other, or they can connect one point to several points.

1. If you use your laptop to connect to the Internet in a mesh network, here's what happens: Your computer detects the nearby network, and you sign on.

2. The protocol that controls the mesh determines the best path for your data to follow. It plans the route that will make the fewest hops before reaching a wired connection or a backhaul node.

3. Your data follows the path that the protocol sets. When your data reaches a node that has a wired connection, it travels over the Internet until it reaches its final destination.

If you're out and about in a city with public access, you can probably do this with no extra equipment. But if you're trying to access the network from home, you may need a stronger radio and possibly a directional antenna. Although signals from the city network are strong enough to make it into your home, the signal from your computer may not be strong enough to make it out again. Most service providers take this into account and provide the necessary equipment for free or for a fee, much like they do with DSL or cable modems.

This system has several advantages over the hubs and spokes of ordinary hot spots. First, since there are fewer wires, it's less expensive. If a few nodes fail, others in the mesh can compensate for it. In addition to being far less expensive than running high-speed cable to every location in a city, it's a lot faster to build.

[Parinaz_M]

Building a Network

[Parinaz_M]

Wireless Network Applications and Public Safety


A municipal network can provide low-cost, high-speed access to the general population. Some cities have used this to justify the expense of the network. In theory, people who are no longer spending money on a high-speed connection will be able to put that money back into the local economy.

Organizations have created wireless networks in developing nations to provide Internet access in locations where traditional networks are impossible. Some U.S. cities hope to use their networks to close the digital divide. Philadelphia, Pennsylvania plans to supplement its network with low-cost computers for low-income families. Plans also include training teen-agers to provide tech support to the people in their communities. You can find out more about these plans through Wireless Philadelphia, the nonprofit organization overseeing the network.

Free or low-cost Internet access is great, but it's only a fraction of what a municipal network can do. In rural areas, wireless networks can give farmers real-time access to security cameras and controls for irrigation and other systems. Networks can make inexpensive Voice over IP (VoIP) phone calls more practical, which can save money for people, businesses and the government. Networks can also make city workers' jobs substantially easier with applications like automated meter reading. Building, fire and restaurant inspectors can file reports without returning to the office, cutting down on their travel time. This is another way that cities can see a return on their investment in the network - they save money on travel, equipment and fees paid for existing communications networks.

Networks can also give police and firefighters remote access to security cameras, blueprints, criminal records and other necessary information. They can let officers show witnesses mug shots or "virtual line-ups" at the scene of a crime. For applications like this, American cities can apply for funding from the Department of Homeland Security.

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Public Safety

[Armageddon]

WOW! I'm impressed!!!!!!! kamtar dokhtari be wireless o wifi alaghe neshoon mide! what's your major?

[Parinaz_M]

Psychology
but i am more intrested in the brain washing idea