Added bit signalling in a telecommunications system

Abstract

A telecommunications system includes an added bit signalling method and apparatus for conveying signalling information between a head end and multiple remote ends connected over a passive distribution network. In accordance with the present invention, an added bit having an identifiable data sequence patterned thereon is appended to each channel within a succession of frames. In the system, the modified channels are broken up, routed reconstructed into a modified framing format and transmitted to their respective destination remote units. Because individual channels within a given frame are broken up and reconstructed into modified frames with channels from other frames, the framing information formerly identified by the framing bit is lost. The present invention therefore appends an added-bit sequence to each channel such that each channel sample carries its own multiframe and alignment information. The remote ends monitor the added bits to locate multiframing and alignment information and to identify individual time slots within each frame. The receiving equipment loops the added bit signal back to the transmitting equipment in the upstream data path. The head end monitors the looped back added bit pattern to ensure the integrity of the outgoing and return data paths. The added bit can be further utilized for out-of-band signalling or to provide an additional data link.