Not all networks are connected with cabling; some networks are

wireless. Wireless LANs use high frequency radio signals, infrared light

beams, or lasers to communicate between the workstations and the file

server or hubs. Each workstation and file server on a wireless network has

some sort of transceiver/antenna to send and receive the data.

Information is relayed between transceivers as if they were physically

connected. For longer distance, wireless communications can also take

place through cellular telephone technology, microwave transmission, or

by satellite.

 

Wireless networks are great for allowing laptop computers or

remote computers to connect to the LAN. Wireless networks are also

beneficial in older buildings where it may be difficult or impossible to

install cables.

 

Wireless networking uses of Radio frequency (RF) technology or

infrared light beams to connect hosts in a network. The benefits of wireless

networking include increased mobility, simple and flexible installation, and easy

scalability. However, wireless networks also have some disadvantages they can

be very expensive, provide poor security, and are susceptible to electrical

interference from lights and radios.

 

Each host on a wireless network has some sort of transceiver / antenna to

send and receive the data. Information is relayed between transceiver as if they

were physically connected. For longer distance, wireless communications can

also take place through cellular telephone technology or by satellite.

 

There are two forms of wireless technology: frequency-hoping spread

spectrum (FHSS) technology and direct sequence spread spectrum (DSSS)

technology. FHSS uses a narrow band 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. DSSS, on the other hand, 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, 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 wide

band noise. It is rejected by most narrow band receivers.

There a two basic devises used in wireless networking, namely: access

points and station adapters. Access points connect the wireless network to the

wired network. Access points have routing capabilities and are programmed to

supply seamless roaming. Station adapters, on the other hand, connect PCs to

the access points via wireless communication.

There are so many considerations when one decides to implement a

wireless network. One of these is range. This refers to the maximum distance

from the access point of the station adapter before communication between the

two fails. The range is usually affected by interference such as microwaves and

other radio interference, as well as interference for structures such as walls and

doors. Another consideration is scalability. This refers to the ability of the

network to take in additional station adapters without degradation in

performance. Security is another consideration. It is well known that there are

many eavesdroppers who listen to wireless network traffic. Hence, most wireless

networks employ the use of encryption techniques to make it impossible for all

but the most sophisticated to gain unauthorized access to network traffic.

 

The two most common types of infrared communications used in schools

are line-of-sight and scattered broadcast. Line-of-sight communication means

that there must be an unblocked direct line between the workstation and the

transceiver. If a person walks within the line-of-sight while there is a

transmission, the information would need to be sent again. This kind of

obstruction can slow down the wireless network.

 

Scattered infrared communication is a broadcast of infrared transmissions

sent out in multiple directions that bounces off walls and ceilings until it

eventually hits the receiver. Networking communications with laser are virtually

the same as line-of-sight infrared networks.

 

Wireless LANs have several disadvantages. They provide poor security,

and are susceptible to interference from lights and electronic devices. They are

also slower than LANs using cabling.