Wireless transmission can be used to provide connectivity from an ISP to an entire building. Wireless can also be used to set up a local area network (LAN) within a building to connect multiple computers to each other and to the Internet.

Point to Point Wireless

Wireless is a high-speed technology that transmits data over radio waves instead of a DSL wire or a coaxial cable. The data is carried on microwave radio signals broadcast from the ISP's nearest radio equipped site bringing a high-speed bi-directional data signal into a building. The signal range can be as much as 10 miles, though in most cases in Ithaca, the range would be less than 1 mile. A line of sight (LOS) must exist between your building and the ISP's radio site, in some cases, a small amount of foliage between the two may be tolerable, but the path cannot be blocked by buildings or hills. Current data rates are in the 11 Mbit range, but a significant amount of overhead is dedicated to protocols and so real data rates are closer to half that, but are still several times the speed of a T1 line. Depending on the service you contract for, you may have all of that bandwidth available for your use, or you may share it with other wireless customers connected to that site. Unlike DSL and cable modems, the bandwidth is symmetrical, so that you have the same bandwidth upstream and downstream.

To install the equipment, the ISP will need a secure space for the radio/router (the size of a mini tower computer), a place that has a view back to their site to mount a small antenna similar in size to a mini satellite dish, and a path to run the cable connecting the two. Although the radio link is very directional and fairly immune to interference, the use of some devices such as 2.4 Ghz wireless telephones or wireless video senders in the building may have to be curtailed.

Local vendors that can transmit wireless signals to your site: LightLink and Clarity Connect.

Wireless LANs

In small buildings or sites where introducing new wiring within the building is particularly difficult, you may want to consider a wireless LAN. To create a wireless LAN, one or more access points (AP) are installed near the centers of computer activity and linked to the server or router that brings the outside data connectivity to the site. Each of the computers that will access the network should have a wireless radio modem card, usually a PCMCIA type II card, installed. Most laptops accept these cards, and adapters can be purchased to allow them to be installed in desktop systems. The range of the cards to the access points is typically 100-250 feet, depending on the building construction; radio waves penetrate wood and plaster easier than concrete and metal. While wireless systems are fairly interference proof, the use of some devices such as 2.4 Ghz wireless telephones or wireless video senders in the building may have to be restricted to prevent interference with the wireless data transmissions. All connections to a common access point share the 11 Mbit bandwidth, however, a significant amount of overhead is dedicated to protocols and so real data rates are closer to half that, resulting in rates similar to 10BASE-T Ethernet wire. Wireless LANs can be connected to DSL or T1 lines, cable modems, or even point to point wireless systems for external connectivity.

Security

Anyone with a suitable card and the correct information can access the network via the access points, so controlling the SSID broadcasts and implementing a security system based on the hardware addresses of known computers may be desirable. Coverage does not stop at the borders of the building, which may be useful if you'd like to use your laptop outside on a nice day, but it also allows unauthorized users nearby to access to your system.

If a server or a LAN has a continuous presence on the network, it is vulnerable to a range of attacks. Unsecured machines on the LAN may be taken over and used to launch new attacks on other machines. If you have a server connecting the LAN to the outside network, you should set it up to act as a firewall to restrict access to those computers protected behind it. This means someone knowledgeable about networking will have to set it up and maintain it as the protective measures do not remain static. An alternative is to let all the traffic pass through, including hostile traffic, and use applications such as BlackICE to protect each machine on the LAN individually.

Local vendors that may be able to assist you in setting up a wireless LAN: LightLink and Danica Computing.

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