Wednesday, June 1, 2011

Characteristics Wireless

Because wireless data uses an unguided medium it suffers from certain problems that do not affect its wired counterpart. One must remember that a wireless user is constrained by the network coverage. If the user moves to an area without coverage, then the user's terminal becomes useless. Although network operators try to minimize these "blackspots" they are inevitable, especially for new networks that are in the process of being deployed.

Multi-path fading, log-normal fading, inter-symbol interference and attenuation are all characteristics of the radio medium. Coupled with the limited amount of frequency spectrum available to wireless applications these attributes mean that the raw bit error rate is greater
than that found in guided mediums. This means that greater overheads are required to maintain acceptable error rates, thus reducing the amount of user data that can be sent per second.

So, wireless systems almost always offer lower bit rates than their wired alternatives.

Wireless systems also tend to have a higher latency than wired systems. For most protocols this is not a big issue, but is something that should be addressed when setting protocol parameters (e.g., timeouts should generally be longer due to the slower response times).

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