Protection Switching for Digital Radio Links

Digital radio link systems need auxiliary equipment to ensure protection against signal quality deterioration due to multipath propagation and equipment failures. In the past, basing on experience with analogue transmission systems, multiline switching arrangements with one protection channel for a few regular channels have been used. Especially for digital transmission systems with high bandwith efficiency special effort to ensure the signal quality in each radio link hop is necessary. Therefore it seems to be advantageous to distinguish between arrangements to ensure the signal quality and the link availability. In the following a system will be described consisting of space diversity reception including adaptive equalization of linear distortions and an additional hot-standby protection switching of transmission equipment.