Radio frequency communication is often used in applications where the signals need to travel through buildings, walls or other obstacles. While communication through these types of obstacles is possible, they do end up reducing the point-to-point range of a system.
In some applications, repeaters can be used to help extend beyond the normal range of a simple point-to-point system. Whenever deploying radios as repeaters, certain factors have to be taken into consideration. Repeaters add delay to the system, so they normally do not work well in streaming data applications or situations where the timing is not adjustable. Also, the repeaters have to be powered and so they need to be deployed where they have access to a power source.
Digi has recently released firmware for both the XStream and XTend families that allows individual radios to be used as repeaters without the need for additional software or firmware on the host side.