Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1998-06-15
2001-11-20
Chin, Wellington (Department: 2664)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S537000
Reexamination Certificate
active
06320876
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention is related in general to the field of telecommunications systems. More particularly, the invention is related to an N:1 transcoder.
BACKGROUND OF THE INVENTION
In the early days of telecommunication, a copper wire medium was used to carry a single information channel. Because the greatest proportion of cost is in the materials and construction of the physical link, telephony engineers have developed ways to pack multiple channels onto a single physical link. Frequency division multiplexing (FDM) and time division multiplexing (TDM) have been devised to multiplex multiple streams of analog and pulse code modulation (PCM) digital signals, respectively, into one. For digital signals, the TDM hierarchy is DSO through DS
4
, where a DSO is a single 0.064 Mbits/sec channel and a DS
4
is 4,032 message channels (DSOs) multiplexed together.
A similar TDM scheme is used in international telephone systems based on 32-channel format. The international digital systems, based on International Telecommunication Union CCITT's G.700 Series Recommendations, are commonly called E
1
or CEPT-
1
. The E
1
signals are based on blocks of 32 channels or time slots, of which time slot
0
and time slot
16
typically are used for control and signaling, respectively.
Although both the U.S. and international digital systems provide for the multiplexing of DSO or E
1
signals to form higher rate signals, greater efficiency of the physical telecommunications link is desired. The capability to transport a higher concentration of voice and data channels advantageously decreases the number of physical links and further lower the toll exacted for connecting the calls.
SUMMARY OF THE INVENTION
Accordingly, there is a need for a transcoder that concentrates multiple E
1
signals onto one E
1
link.
In accordance with the present invention, an N:1 transcoder is provided which eliminates or substantially reduces the disadvantages associated with prior systems.
In one aspect of the invention, an N:1 transcoder with a compression data path that includes an uncompressed digroup circuit receiving N incoming uncompressed signals and extracting a plurality of control, signaling, and voice/data traffic channels therefrom, a compressor coupled to the uncompressed digroup circuit and compressing data in selected ones of the extracted voice/data channels, and a compressed data circuit coupled to the compressor packing the compressed data into predetermined channels of one compressed signal, and further providing control, signaling, and performance monitoring information embedded therein.
In another aspect of the invention, four E
1
signals are compressed by the transcoder of the present invention and packed into one compressed E
1
signal.
In yet another aspect of the invention, the compressed E
1
signal includes control, monitoring, and status information of channels in the four E
1
signals embedded in predetermined channels of the compressed E
1
signal.
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International Telecommunication Union, “General Aspects of Digital Transmission Systems; Terminal Equipments; Physical/Electrical Characteristics of Hierarchical Digital Interfaces,” CCITT, G.703, Geneva 1991, pp. 1-39.
International Telecommunication Union “General Aspects of Digital Transmission Systems; Terminal Equipments; Synchronous Frame Structures Used at Primary and Secondary Hierarchical Levels,” CCITT, G.704, Geneva 1991, pp. 1-33.
Hodges, et al., “Development and Testing of DCME Systems”, British Telecommunications Engineering, Part 3, Oct. 1992, pp. 205-212.
Kato, et al., “DCME System NCM-501”, NEC Research & Development, No. 3, Jul. 1991, pp. 389-399.
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Jette Michael H.
Tatachar Mike M.
Virdee Harbhajan S.
Alcatel USA, Inc.
Baker & Botts L.L.P.
Chin Wellington
Yao Kwang B.
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