Wireless LAN Issues
Although wireless LANs offer some real promise, they also offer their own set of problems and issues, including security, signal interference, and interoperability. In this article, Jim Geier explores some of the issues surrounding the implementation of a wireless LAN.
This material is excerpted from Jim Geier's book, Wireless LANs: Implementing Interoperable Networks (Macmillan Technical Publishing, 1999).
Wireless LANs certainly offer tremendous benefits. However, project managers and design engineers should be aware of the following implications that surround the implementation and use of wireless networking:
Radio signal interference
Transmitted signals can combine with reflected ones to corrupt the signal detected by the receiver. This is known as multipath distortion. Delay spread is the amount of delay experienced by the reflected signals compared to the primary signal. As delay spread increases, the signal at the receiver becomes more distorted and possibly undetectable, even when the transmitter and receiver are within close range. This type of impairment has a greater impact on higher data rates because transmitted symbols are closer together.
Multipath propagation can be a significant problem, especially with indoor applications. Office furniture, walls, and machinery are obstacles that can redirect parts of the transmitted signal. Wireless LAN manufacturers compensate for the effects of multipath propagation by using special processing techniques. As examples, equalization and antenna diversity are methods that vendors use to reduce the problems arising from multipath propagation. If significant multipath propagation is present, then it may be necessary to operate the wireless LAN at lower data rates.