Bit compression multiplexing

• US 4,581,737 A
• Filed: 12/12/1983
• Issued: 04/08/1986
• Est. Priority Date: 12/12/1983
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: AT&T, Inc.
• Inventors: Sparrell, Duncan K.
• Primary Examiner(s): ORSINO JR, JOSEPH
• Application Number:
  US06/560,232
• Time in Patent Office: 848 Days
• Field of Search: 370/99, 370/105, 370/110.1, 370/118
• US Class Current: 370/477
• CPC Class Codes: H04J 3/12 Arrangements providing for calling or supervisory signals
• CPC Class Codes: H04J 3/18 using frequency compression and subsequent expansion of the individual signals

Abstract

A bit compression multiplexer for a pair of time division multiplexed digital bit streams each one of which includes a plurality of PCM encoded signals deposited in separate and distinct channels and signaling bits multiplexed therewith. The encoded signals are bit compressed (22), and then multiplexed and grouped (25) into clusters. Each of the multiplexed compressed signals occupies a separate and distinct channel of a repetitive frame that includes a plurality of clusters and a corresponding number of additional channels, called delta channels, each one of which is associated with a given cluster and is proximate thereto. The signaling bits are extracted (21) from the pair of digital bit streams, reformatted (24) and then placed in predetermined bit positions of the delta channels. The signaling bits in a given delta channel are associated with the compressed signals of a cluster proximate thereto. The combination of a cluster and its related delta channel comprise a bundle. A framing bit pattern is developed (23) for each bundle and the framing bits are placed into a predetermined bit position of each of the delta channels (24). The framing bit pattern is arranged to detect frame slips which occur either at a transmitting bit compression multiplexer, at a receiving bit compression multiplexer or at other components of the transmission system, for example, at a Digital Access and Cross-connect System (DACS).

Claims

1. A bit compression multiplexing system for a pair of time division multiplexed digital bit streams each of which includes a plurality of PCM encoded signals deposited in separate and distinct channels of a repetitive frame and signaling bits multiplexed therewith comprising:

means for bit compressing the encoded PCM signals into differential PCM signals;

means for multiplexing the compressed differential PCM signals and grouping the same into clusters, each of the clusters including a predetermined number of multiplexed compressed signal channels and each of the compressed differential PCM signals occupying a separate and distinct channel of a repetitive frame that includes a plurality of said clusters and a corresponding plurality of additional channels each one of which is associated with a given cluster and is proximate thereto, wherein a predetermined number of said repetitive frames forms a repetitive superframe;

means for extracting and reformatting the signaling bits of said time division multiplexed digital bit streams and placing the same in predetermined ones of said plurality of additional channels in the repetitive frames of said superframe, the signaling bits in a given additional channel being associated with the compressed differential PCM signals of a cluster proximate thereto; and

means for developing a framing bit pattern for each of said plurality of clusters and for inserting the bits of the same into a predetermined repetitive bit position of each of said additional channels in the repetitive frames of said superframe, said framing bit pattern having an alternating bit pattern except at at least one prescribed location where at most two adjacent bit positions are identical.

2. A bit compression multiplex system as defined in claim 1 wherein said framing bit pattern prescribed location is at the framing pattern boundary.

3. A bit compression multiplex system as defined in claim 1 wherein said framing bit pattern includes at least two sub-framing bit patterns each having an alternating bit pattern wherein the bit pattern of one of said sub-framing bit patterns alternates in inverse fashion relative to the alternating bit pattern of the other sub-framing bit pattern.

4. A bit compression multiplex system as defined in claim 3 wherein said sub-framing bit patterns form an overall framing bit pattern having at most two adjacent bit positions identical at the sub-framing bit pattern boundaries.

5. A bit compression multiplex system as defined in claim 4 wherein said sub-framing bit patterns each have a prescribed number of framing bits in predetermined relationship to the total number of framing bits.

6. A bit compression multiplex system as defined in claim 5 wherein the relationship is N=m+n where N is the total number of framing bits, m is the number of framing bits in one sub-framing bit pattern and n is the number of framing bits in the other sub-framing bit pattern.

7. A bit compression multiplex system as defined in claim 6 wherein N is twenty-four (24), m is twelve (12) and n is twelve (12).

8. A bit compression multiplex system as defined in claim 7 wherein the framing bit pattern is

9. A bit compression multiplex system as defined in claim 7 wherein the framing bit pattern is

10. A bit compression multiplex system as defined in claim 9 wherein the digital bit streams are DS1 signals.

11. A bit compression multiplexing method for a pair of time division multiplexed digital bit streams each of which includes a plurality of PCM encoded signals deposited in separate and distinct channels of a repetitive frame and signaling bits multiplexed therewtih comprising the steps of:

bit compressing the encoded PCM signals into differential PCM signals;

multiplexing the compressed differential PCM signals and grouping the same into clusters, each of the clusters including a predetermined number of multiplexed compressed signal channels and each of the compressed differential PCM signals occupying a separate and distinct channel of a repetitive frame that includes a plurality of said clusters and a corresponding plurality of additional channels each one of which is associated with a given cluster and is proximate thereto, wherein a predetermined number of said repetitive frames forms a repetitive superframe;

extracting the signaling bits from the pair of time division multiplexed digital bit streams;

reformatting the extracted signaling bits and placing the same in predetermined ones of said plurality of additional channels in the repetitive frames of said superframe, the signaling bits in a given additional channel being associated with the compressed differential PCM signals of a cluster proximate thereto;

and developing a framing bit pattern for each of said plurality of clusters and inserting the bits of the same into a predetermined repetitive bit position of each of said additional channels in the repetitive frames of said superframe, said framing bit pattern having an alternating bit pattern except at at least one prescribed location where at most two adjacent bit positions are identical.

12. The method as defined in claim 11 wherein said framing bit pattern includes at least two sub-framing bit patterns each having an alternating bit pattern wherein the bit pattern of one of said sub-framing bit patterns alternates in inverse fashion relative to the alternating bit pattern of the other sub-framing bit pattern forming an overall framing bit pattern having at most two adjacent bit positions identical at the sub-framing bit pattern boundaries.