5.1 Long Distance Comms

5.1 Long Distance Communications

Due to the nature of modern business there may be different devices in varied locations that have to communicate. Take the instance of a business with its headquarters in one city, e.g. Glasgow, and a sales outlet in Paris. There may be many devices at the Paris end that require connectivity to headquarters. How can this be achieved?

A possible solution would be to have a direct connection from each device to the main system at headquarters; however, this would be impractical and uneconomic. A better solution would be for all of the devices to share a single high speed connection to headquarters. This can be achieved by a technique known as multiplexing.

Multiplexing and Line Sharing

When multiplexing is successfully implemented it is transparent to the end users. As far as they are concerned they are directly connected to the receiving system and are not sharing the channel with anyone else.

A multiplexor is specialist communication hardware that combines many signals to permit use of a single communications link. The bandwidth of a multiplexor depends on the number of users using the link. Another term used to describe multiplexor is concentrator.

In order to allow users access to a single link a system must be set up to ensure that all users are given equal access. This can be achieved by either giving users a time slice of the channel or some of the frequency space. The use of multiplexing has been the backbone of telephone systems around the world.

Next: 5.2 Types of Multiplexing