Wireless Classroom Introduction Network Diagram Links

What is wireless networking?
Wireless networking is the use of Radio Frequency (RF) technology to connect workstations in a Local Area Network (LAN) or LAN's in a Wide Area Network (WAN). Current technology allows for Ethernet speeds with limited or no wired connections. 

Uses for Wireless networking in an Academic Environment
Some schools may find it impractical to use a wired network due to factors such as:

• Asbestos blocking the running of wires
• Cost of running wires makes a wired network too expensive
• Teachers moving from classroom to classroom

Schools can use the alternate technology of wireless networking to provide computer connectivity in a cost effective means. Not only has wireless been used in school, but also hospitals, warehouses, retail stores, trade shows, universities, etc.

Benefits 
The benefits of wireless networking include increased mobility, simple and flexible installation, and easy scalability.

Technology
There are two forms of wireless technology: Frequency-Hopping Spread Spectrum Technology and Direct Sequence

Frequency-hopping spread-spectrum (FHSS) uses a narrowband carrier that changes frequency in a pattern known to both transmitter and receiver. Properly synchronized, the net effect is to maintain a single logical channel. To an unintended receiver, FHSS appears to be short-duration impulse noise.

Direct-sequence spread-spectrum (DSSS) generates a redundant bit pattern for each bit to be transmitted. This bit pattern is called a chip (or chipping code). The longer the chip, the greater the probability that the original data can be recovered (and, of course, the more bandwidth required). Even if one or more bits in the chip are damaged during transmission, statistical techniques embedded in the radio can recover the original data without the need for retransmission. To an unintended receiver, DSSS appears as low-power wideband noise and is rejected (ignored) by most narrowband receivers.

Wireless Devices
There are 3 basic devices used in wireless networking:

1. Access points: These devices connect the wireless network to the wired network. They have a standard 10-base-T connector and IP routing capabilities. They also control access to the network and load bearing of all access points on the network. Some are programmed to supply seamless roaming.
2. Station Adapters: These devices connect desktop computers to the access points via wireless communication. Station adapters connect to the computer using a 10-base-T connection, which means it is necessary for the computer to have a network card. Station adapters connect to either one or four depending on the version of the device purchased.
3. PCMCIA Adapter: These devices connect laptops and any other PCMCIA Type 2 compatible devices to the access point. This device is connected to the computer sing a PCMCIA Type 2 connection, which is standard on current laptop computers and can be an accessory for some palmtops. PCMCIA adapters are usable with only one computer.

Considerations

Range: The range of the wireless network is an important consideration when using a wireless network. Access point and station adapters have a range of 3280 ft in open space and 200 ft-650 ft indoors. PCMCIA adapters have an open space range of 2200 ft and an indoor range of 300 ft. These ranges are affected by interferences such as microwaves and other radio interferences, as well as interference for structures such as walls and doors.

Throughput: The amount of data transferable using wireless devices is important. The amount will not be as great as a standard wired LAN, but will be greater than using a modem or other such devices. The access point, PCMCIA adapter, and station adapter have a data rate of 11mb. This data rate, however, is not throughput. When data is being transferred via wireless networking it requires a certain amount of overhead that is also included in the data rate. Most networks do not require more throughputs than provided by the devices.

Integrity: The wireless network is a generally stable form of communication. The robust designs of proven wireless technology and the limited distance over which signals travel result in connections that are far more robust than cellular phone connections and provide data integrity performance equal to or better than wired networking. 

Interoperability: Wireless devices provide the ability to connect to wired LAN with ease. Adapters and access points work like a wired connection, except that no wires are necessary. The computer connects to other computers just as it would for a wired connection, because wireless devices use a "transparent protocol". These devices are compatible with IEEE 802.11b standards, which is the industry standard for wireless devices. Although industry standards continue to evolve, many devices work with devices made by another manufacturer.

Scalability: Wireless networks can be designed to be extremely simple or quite complex. Wireless networks can support large numbers of nodes and/or large physical areas by adding access points to boost or extend coverage.

Simplicity of installation and use: Users need very little new information to take advantage of wireless LANs. Because of the nature of a wireless LAN is transparent to a user's network operating system, applications work the same as they do on wired LANs. Wireless devices incorporate a variety of diagnostic tools to address issues associated with the wireless elements of the system; however, products are designed so that most users rarely need these tools.

Security: Because wireless technology has roots in military applications, security has long been a design criterion for wireless devices. Security provisions are typically built into wireless LANs, making them more secure than most wired LANs. It is extremely difficult for unintended receivers (eavesdroppers) to listen in on wireless LAN traffic. Complex encryption techniques make it impossible for all but the most sophisticated to gain unauthorized access to network traffic. In general, individual nodes must be security-enabled before they are allowed to participate in network traffic.

Battery Life for Mobile Platforms: End-user wireless products are designed to run off the AC or battery power from their host notebook or hand-held computer, since they have no direct wire connectivity of their own. WLAN vendors typically employ special design techniques to maximize the host computer's energy usage and battery life.

Safety: The output power of wireless LAN systems is very low, much less than that of a hand-held cellular phone. Since radio waves fade rapidly over distance, very little exposure to RF energy is provided to those in the area of a wireless LAN system. Wireless LANs must meet stringent government and industry regulations for safety. No adverse health affects have ever been attributed to wireless LANs.