Method for increasing ISDN channel capacity of TDM serial communication link for digital subscriber line channels

For use with a digital communication network having a serial communication link, which normally conveys thereover a multiplicity J of basic time division multiplexed (TDM) digital subscriber line (DSL) channels, each basic TDM DSL channel containing first and second multibit bearer (B) information signal time slots and a multibit data (D) information signal time slot, said multibit D information time slot containing signalling information for said B information time slots, a maintenance channel bit and a plurality of auxiliary overhead bits, said serial communication link being coupled to a multiple channel bank, that is normally interfaced with a multiplicity M of integrated services digital network (ISDN) channels, a method of controlling the multiplexed transmission of TDM DSL channels over said serial communication link so as to increase the number of TDM DSL channels that may be conveyed by said serial communication link and thereby the number of ISDN channels that may be interfaced with said channel bank comprising the steps of:

• (a) generating a plurality of a plurality of multibit B information signal time slots, associated with said J basic TDM DSL channels and an additional number N of TDM DSL channels;
• (b) generating a first multibit D channel information signal time slot, which includes multiple pairs of first and second D bits containing signalling information for B information signal time slots contained within a first number of said condensed TDM DSL channels;
• (c) generating a second multibit D channel information signal time slot, which includes multiple pairs of first and second D bits containing signalling information for B information signal time slots contained within a second number of said condensed TDM DSL channels;
• (d) generating third and fourth multibit information signal time slots, which include N pairs of first and second D channel information bits containing signalling information for B information time slots within said N additional TDM DSL channels, and maintenance channel bits associated with said condensed TDM DSL channels;
• and
• (e) combining the contents of said B information signal time slots, said first and second D channel information signal time slots and said third and fourth multibit information signal time slots with one another to form said plurality of condensed TDM DSL channels, within a plurality K of time division multiplexed time slots.

For use with a digital communication network having a serial communication link, which normally conveys thereover a multiplicity J of basic time division multiplexed (TDM) digital subscriber line (DSL) channels, each basic TDM DSL channel having first and second multibit bearer (B) information signal time slots and a multibit data (D) information signal time slot, said D time slot containing signalling information for B information time slots, a maintenance bit and a plurality of auxiliary bits, said serial communication link being coupled to a channel bank, normally interfaced with a multiplicity M of integrated services digital network (ISDN) channels,

• a channel bank arrangement for multiplexing condensed TDM DSL channels over said serial communication link, so as to augment said multiplicity J of TDM DSL channels by an additional number of N TDM DSL channels, and thereby increase the total number of TDM DSL channels that may be conveyed by said serial communication link, and thus the number of ISDN channels that may be interfaced with said channel bank, said channel bank arrangement comprising a multiplexer having a plurality P of input ports respectively coupled to receive a plurality of P ISDN channels, where P=J+N, a respective one of said P condensed TDM DSL channels containing first and second multibit B information signal time slots, and a pair of D channel information bits, a serial output port coupled to said serial communication link, and a control port, and a controller coupled to said multiplexer for controlling the manner in which said plurality of P ISDN channels are multiplexed by said multiplexer onto said serial communication link in accordance with a prescribed multiplexing format that includes:
• a first multibit D channel information signal time slot, which contains multiple pairs of first and second D bits, containing signalling information for B information signal time slots contained within a first number of said P condensed TDM DSL channels;
• a second multibit D channel information signal time slot, which contains multiple pairs of first and second D bits, containing signalling information for B information signal time slots contained within a second number of said P condensed TDM DSL channels;
• third and fourth multibit information signal time slots, which contain N pairs of first and second D channel bits containing signalling information for B information time slots within said N additional TDM DSL channels, and P maintenance bits associated with said P condensed TDM DSL channels;
• and wherein
• the contents of said B information signal time slots, said first and second D channel information signal time slots and said third and fourth multibit information signal time slots are combined with one another to form said plurality P of condensed TDM DSL channels, within a plurality K of time division multiplexed time slots.