Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via frequency channels
Reexamination Certificate
1998-01-27
2001-03-27
Horabik, Michael (Department: 2735)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via frequency channels
C370S437000
Reexamination Certificate
active
06208664
ABSTRACT:
BACKGROUND
This invention is related to high-bit-rate digital subscriber line (HDSL) modules for telecommunications channel unit cards.
In the early days of telecommunications, a copper wire was used to carry a single information channel. Because the large majority of cost is in the materials and construction of the physical link, telephony engineers since have developed ways to pack multiple communications 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 a single stream. For digital signals, the time division multiplexing hierarchy is represented as DS0 (Digital Signal) through DS4, where a DS0 is a single 0.064 Mb/s channel, a DS1 is 24 DS0s multiplexed together, a DS2 is 96 DS0s multiplexed together, a DS3 is 672 DS0s multiplexed together, and a DS4 is 4,032 DS0s multiplexed together. The hierarchy DS1 through DS4 also is referred to as T1, T2, T3, and T4 when using a copper medium for transmission.
A similar time division multiplexing scheme, based on International Telecommunication Union CCITT's G.700 Series Recommendations, uses a 32-channel format referred to as E1, or CEPT-1, where each channel corresponds to a DS0 (0.064 Mb/s) signal. Thus, a E1 signal is based on 32 DS0s multiplexed together, a E2 is 128 DS0s multiplexed together, a E3 is 512 DS0s multiplexed together, and a E4 is 2,048 DS0s multiplexed together.
A digital loop carrier (DLC) at a central terminal (CT) is a multiplexor which can multiplex multiple analog and digital signals from subscriber telephone lines into a single multiple digital signal such as a T1/E1 signal. A mirror DLC located at a remote terminal (RT) can decode the multiplexed T1/E1 signal into a form suitable for transmission over subscriber telephone lines. This data flow also occurs in the opposite direction from RT to CT.
Each DLC essentially is a special purpose computer containing standard control, memory, power, etc. components but also a number of interface cards (line cards) for converting analog and digital signals from subscriber telephone lines into formatted digital data signals. Different types of interface cards service different types of subscriber telephone lines. Examples of interface cards include POTS (Plain Old Telephone Service) cards for analog telephone lines, FOX cards for fiber optic lines, ISDN (Integrated Services Digital Network) cards for ISDN lines, and a number of other wideband service option cards. After the appropriate interface cards convert the subscriber telephone line signals into formatted digital data signals, a DLC at a central terminal constructs a single E1 signal by means of time division multiplexing. At a remote terminal, the DLC decodes the E1 signal to deliver formatted digital data back to the interface cards. Interface cards convert the formatted digital data into a form suitable for transmission over subscriber telephone lines. The most mature technology for transmitting over these lines (e.g., standard unshielded twisted pair) is HDSL. HDSL, which involves special electronics at both the central office and the customer premise, allows the provisioning of T1/E1 local loop circuits much more quickly and at much lower cost than through conventional means.
SUMMARY
In general, in various implementations, the invention may include one or more of the following features.
A telecommunications channel unit card includes a subscriber bus interface for communicating subscriber bus signals with a digital loop carrier matrix, wideband channels for communicating wideband telecommunications signals with the subscriber bus interface and an external network, and at least one high-bit-rate digital subscriber line (HDSL) module capable of being coupled selectively to at least one of the wideband channels to facilitate HDSL-based communications between the telecommunications channel unit card and the external network.
The telecommunications channel unit card can include at least one span circuit including a line interface unit (LIU) portion and a channel framer portion.
The HDSL module can be coupled to at least one of the wideband channels through the channel framer portion of the span circuit.
The outgoing wideband telecommunications signals received from at least one of the wideband channels can be framed using the channel framer portion of the span circuit.
The telecommunications channel unit card also can include a conversion circuit for converting subscriber bus signals and wideband telecommunications signals.
The wideband telecommunications signals can comprise E1 or T1 signals.
The digital loop carrier matrix can comprise a bandwidth allocator, processor and timing unit (BPT) card.
In general, in another aspect, a method of configuring a telecommunications channel unit card includes providing a subscriber bus interface for communicating subscriber bus signals with a digital loop carrier matrix, connecting the subscriber line interface with wideband channels, and selectively coupling a high-bit-rate digital subscriber line (HDSL) module to at least one of the wideband channels to enable HDSL-based communications.
The channel unit card can include at least one span circuit having a line interface unit (LIU) portion and a channel framer portion.
The HDSL module can be coupled to at least one of the wideband channels through the channel framer portion of the span circuit.
The outgoing wideband telecommunication signals from at least one of the wideband channels can be framed using the channel framer portion of the span circuit.
In general, in another respect, a method of configuring the channel unit card of claim
8
includes converting the subscriber bus interface signals and the wideband telecommunications signals.
The wideband telecommunications signals can comprise E1 or T1 signals.
The digital loop carrier matrix can comprise a bandwidth allocator, processor, and timing unit (BPT) card.
In general, in another respect, a telecommunications channel unit card includes a subscriber bus interface for communicating subscriber bus interface (SBI) signals with a bandwidth allocator, processor and timing unit (BPT) card, wideband channels including a processor capable of processing message-based applications, an application specific integrated circuit (ASIC) between the subscriber bus interface and span circuits capable of converting the subscriber bus interface signals and E1 signals, and three span circuits each including one line interface unit (LIU) portion and one E1 framer portion for interfacing between the ASIC and an external network, the E1 framer portion framing the E1 signals for transmission over the external network and for recovering the E1 signals from reception over the external network, the line interface unit capable of connecting to the external network when the channel unit card functions as an E1 card, and two high-bit-rate digital subscriber line (HDSL) modules having their clocks and signals pins connected to the corresponding clocks and signals pins of two corresponding E1 framer portions to facilitate HDSL-based communications between the telecommunications channel unit card and the external network.
Advantages may include one or more of the following. A card that sends and receives multiple HDSL signals is able to send and transmit multiple signals per card, thus lowering the per-line cost. Because only one card needs to be manufactured to produce both a multiple E1 card and a multiple HDSL card, the cost per line is further reduced. Moreover, having channel cards that contain multiple signal channels allow more subscribers to be served.
Additional features and advantages of the invention will be readily apparent from the following description, drawings, and claims.
REFERENCES:
patent: 4993019 (1991-02-01), Cole et al.
patent: 5014268 (1991-05-01), Tyrrell et al.
patent: 5105421 (1992-04-01), Gingell
patent: 5237563 (1993-08-01), McNulty
patent: 5243593 (1993-09-01), Timbs
patent: 526723
Klecka, III Rudolph B.
Plummer William M.
Alcatel USA Source L.P.
Fish & Richardson P.C.
Horabik Michael
Jones Prenell
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