Quarter-rate 2B1Q ISDN architecture with embedded differential delay compensation for extending range of DDS communications
AssigneeAdtran, Inc.
InventorPhilip David Williams
Life of this patent
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Abstract
The transmission distance for DDS subscriber lines over a repeaterless four-wire link is extended to customer premises beyond the standard four-wire loop range of approximately 18 kft (56 kbps, 56 kbps with secondary channel capability, and 64 kbps) by employing commercially available ISDN transceiver chip hardware to multiplex a DDS data channel into quarter-rate (2B1Q) ISDN channels. At least one of a signalling channel and an out-of-band maintenance channel is used to convey differential delay compensation information, without modifying the framing structure of the transported channels, or requiring additional bandwidth for a separate framing channel.
Claims24
A method of transporting dataphone digital services DDS communications over a four-wire, repeaterless transmission path comprising the steps of:
- (a) demultiplexing DDS input signals into quarter-rate ISDN channels for transmission over said four-wire, repeaterless transmission path;
- (b) measuring differential transport delay between different portions of said four-wire, repeaterless transmission path;
- (c) conveying measured differential transport delay determined in step (b) in a non-bearer channel portion of one of said quarter-rate ISDN channels;
- and
- (d) using said measured differential transport delay conveyed in step (c) to time align-multiplex said quarter-rate ISDN channels into DDS output signals.
A system for transporting dataphone digital services DDS communications over a repeaterless, four-wire transmission path between first and second sites comprising:
- a first communication device, coupled with said first site, and being operative to demultiplex DDS input signals into quarter-rate ISDN channels for transmission over said four-wire transmission path, and to convey, in a non-bearer channel portion of one of said quarter-rate ISDN channels, information representative of differential transport delay between different portions of said four-wire transmission path;
- and
- a second communication device, coupled with said second site, and being operative to time align-multiplex received quarter-rate ISDN channels into DDS output signals in accordance with said differential transport delay information.
A system for transporting dataphone digital services DDS communications over a repeaterless, four-wire transmission path comprising:
- a first communication device coupled to a first portion of said four-wire transmission path and being operative to demultiplex a DDS input data stream supplied thereto from a T-carrier interface into quarter-rate ISDN communication channels, and to transmit said quarter-rate ISDN communication channels over said four-wire transmission path, such that framing structure of one of said quarter-rate ISDN communication channels has a prescribed lead time relative to framing structure of another of said quarter-rate ISDN communication channels;
- and
- a second communication device, coupled to a second portion of said four-wire transmission path, and being operative to measure differential delay between framing structures of selected ones of said quarter-rate ISDN communication channels, that have been respectively received from different portions of said four-wire transmission path, to demultiplex digital signals supplied by a signalling link to said second communication device into further quarter-rate ISDN communication channels, and to transmit four further quarter-rate ISDN communication channels over said four-wire transmission path from said second communication device to said first communication device, and to transmit, in at least one of a signalling channel and an out-of-band maintenance channel portion of one of said further quarter-rate ISDN channels, a measure of differential delay between said different portions of said four-wire transmission path.
Dependencies are inferred from the claim text.