CA2050751A1 - Asynchronous x-bit signalling in ds2 signal format - Google Patents
Asynchronous x-bit signalling in ds2 signal formatInfo
- Publication number
- CA2050751A1 CA2050751A1 CA002050751A CA2050751A CA2050751A1 CA 2050751 A1 CA2050751 A1 CA 2050751A1 CA 002050751 A CA002050751 A CA 002050751A CA 2050751 A CA2050751 A CA 2050751A CA 2050751 A1 CA2050751 A1 CA 2050751A1
- Authority
- CA
- Canada
- Prior art keywords
- bit
- formatted signal
- asynchronous
- communications
- bits
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 230000011664 signaling Effects 0.000 title claims description 8
- 238000004891 communication Methods 0.000 claims abstract description 38
- 239000000835 fiber Substances 0.000 claims description 8
- 230000005540 biological transmission Effects 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 6
- 238000009432 framing Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 5
- 230000003287 optical effect Effects 0.000 description 3
- 125000004122 cyclic group Chemical group 0.000 description 2
- 241000384969 Priva Species 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Landscapes
- Time-Division Multiplex Systems (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An asynchronous protocol is overlaid on the X-bit of a DS2 formatted signal to provide a private communications channel for transport of information bytes thereon.
An asynchronous protocol is overlaid on the X-bit of a DS2 formatted signal to provide a private communications channel for transport of information bytes thereon.
Description
2 ~ rl ~ 1 ASYNCHRONOUS X-BIT SI(;NALLING IN DS2 SIGNAL FORMAT
Field of the Invention ~
The present invention relates generally to telecommunications. In particular, the present invention relates to an X-bit communications technique for use in the DS2 signalling format.
Summary of the Invention The use of asynchronous end-to-end communications are well known in the telecommunications field. The present invention applies an asynchronous protocal to the X-bit in the DS2 signalling format. The end-to-end communications system includes a conversion means for converting a plurality of electrical signals to DS2 signal format for transport on fiber optic cables and then re-converting the DS2 signal. An asynchronous protocol overlays the X-bit of the DS2 signal format in the overall communications system to provide a privat~ communications channel transporting information bytes from end-to-end in addition to the transport of other information of the DS2 signal format.
Framing means frames the information bytes by prepending and amending control bytes thereto and appending error-checking bytes thereto.
.
1 r~
Brief Description of the Drawinqs Fig. 1 is a block diagram of a DS2 co~nunications unit which provides end-to-end transport of digital signals;
Fig. 2 is a diagram showing components of the DS2 signal format;
Fig. 3 shows a bloc~ diagram of the X-bit signalling protocal of the present invention; and Fig. 4 shows the framed message transported via the X
bit protocal of the present invention.
Detailed Description of the Preferred Embodiment In the following detail description of the preferred embodiment references are made to ~he figures which form a part hereof and in which the invention may be practiced. This embodiment is described in sufficient detail to those skilled in the art to practice the invention and it is to be understood that other embodiments may be utilized without departing from the spirit and scope of the present invention. The following detailed description is therefore not to be taken in a limiting sense and the scope of the present invention is defined by the appendPd claims.
In ~ig. 1, there is shown a block diagram of a DS2 communications unit 10 which provides end-to-end transport from transmitting end 12 to receiving end 14 of four T1 signals 16 over a pair of single-mode fiber optic cables r!"'' 24. To accomplish this t~sk, a converter module 18 accep~s four electrical T1 inputs 16. The converter module 18 includes a multiplexer 20 for multiplexing the T1 inputs to a higher level DS2 format (a Bell System standard). The con~erter module 18 also includes an elec~rical to optical converter 22 for conversion of the DS2 siynals to optical DS2 signals 30 and injects them onto the fiber optic cables 24. Since the DS2 communications unit 10 is an end-to-end system, each converteL module at one end has a counterpart lQ at the other end. This counterpart converter module 28 includes an optical to electrical converter 32 and demultiplexer 34. Each end 12, 14 has a ~'private~
communications channel with the other end to allow status message transfer of framed message 50. This private communication occurs over the X-bit 60 of the DS2 formatted signal 30, Fig 2.
Fig. 2 shows components of the DS2 formatted signal 30. The DS2 formatted signal 30 has a bit-rate of 6.312 Megabits per second (Mb/s). This bit-rate was chosen to allow for DS2 framing bits 62, information bits 64, stuff bits 66, and an overhead bit, called the X-bit 60.
The X-bit occurs every 186 microseconds in the DS2 signal 30. Please refer to BellCore document TR-TSY-00499, hereby incorporated by reference, for further details. Because the fiber optic output of a converter module can only be connected to the fiber optic input of other converter modules, the X~blt 60 in ~he DS2 formatted signal 30 can be used in a specified fonnat. Thus, the X-bit 60 is u~ed as an end-to-end pri~ate communications channel 40.
Fig. 3 discloses a block diagram of the private communications channel 40 be~ween ~ransmi~ting end 12 and receiving end 14. ~n asynchronous communications protocol 52, running at 2400 baud, is imposed on the X-bit 60 of the DS2 formatted signal to provide this communications channel 40. The asynchronous communlcations protocol 52 overlaid on the X-bit 60 results in in~ormation transfer bytes 56.
These information transfer bytes 56 have the following parameters: eight bits; one stop bit; no parity bit; one start bit; 2400 bits/second. The message transfer in the end-to-end private communications channel 40 occurs in higher level structures called frames 50 which include four information transfer bytes 56 therein. This framing technique 54 (derived from IBM~s BiSynchronous forma~) prepends and appends certain control bytes 58,(Fig. 4)to the information transfer bytes 56. The framing technique 54 also appends two bytes of error checking information to the information by'ces, generally a cyclic redundancy check (CRC) 59, Fig 4.
Fig. 4 shows in block form frame 50, which is the message transferred on private communications channel 40 in frame fonmat. Frames 50 include control bytes DLE, STX, and ETX (per ASCII standards). These control bytes 54 _ .. . .. ..
~9, ~7 -3:~
frame information byte~ 56 of the message and allow transmission of all 256, 8 bit codes. Also included .in frame 50, as indicated previously, are two bytes of cyclic redundancy checks 59 for error checking.
Although the present invention has been described above in a preferred form, those skilled in the art will readily appreciate that various modifications may be made to it without departing from the spirit and scope of the invention, as bounded by the claims of the application itself.
. .
,3 ~hat is claimed is~
1. A DS2 end-to-end communications unit, comprising:
conversion means for converting a plurality of electrical signals to a DS2 formatted signal and for reconverting said DS2 formatted signal, said DS2 formatted signal having an X-bit; and an asynchronous protocol overlaid on said X-bit o~ said DS2 formatted signal to provide a priva~e communications channel for transport of information bytes thereon.
2. A DS2 communications unit according to claim 1 further comprising framing means for framing said information bytes, said framing means including prepending and appending control bytes and error-checking bytes to said information bytes.
.. . . ... .
Field of the Invention ~
The present invention relates generally to telecommunications. In particular, the present invention relates to an X-bit communications technique for use in the DS2 signalling format.
Summary of the Invention The use of asynchronous end-to-end communications are well known in the telecommunications field. The present invention applies an asynchronous protocal to the X-bit in the DS2 signalling format. The end-to-end communications system includes a conversion means for converting a plurality of electrical signals to DS2 signal format for transport on fiber optic cables and then re-converting the DS2 signal. An asynchronous protocol overlays the X-bit of the DS2 signal format in the overall communications system to provide a privat~ communications channel transporting information bytes from end-to-end in addition to the transport of other information of the DS2 signal format.
Framing means frames the information bytes by prepending and amending control bytes thereto and appending error-checking bytes thereto.
.
1 r~
Brief Description of the Drawinqs Fig. 1 is a block diagram of a DS2 co~nunications unit which provides end-to-end transport of digital signals;
Fig. 2 is a diagram showing components of the DS2 signal format;
Fig. 3 shows a bloc~ diagram of the X-bit signalling protocal of the present invention; and Fig. 4 shows the framed message transported via the X
bit protocal of the present invention.
Detailed Description of the Preferred Embodiment In the following detail description of the preferred embodiment references are made to ~he figures which form a part hereof and in which the invention may be practiced. This embodiment is described in sufficient detail to those skilled in the art to practice the invention and it is to be understood that other embodiments may be utilized without departing from the spirit and scope of the present invention. The following detailed description is therefore not to be taken in a limiting sense and the scope of the present invention is defined by the appendPd claims.
In ~ig. 1, there is shown a block diagram of a DS2 communications unit 10 which provides end-to-end transport from transmitting end 12 to receiving end 14 of four T1 signals 16 over a pair of single-mode fiber optic cables r!"'' 24. To accomplish this t~sk, a converter module 18 accep~s four electrical T1 inputs 16. The converter module 18 includes a multiplexer 20 for multiplexing the T1 inputs to a higher level DS2 format (a Bell System standard). The con~erter module 18 also includes an elec~rical to optical converter 22 for conversion of the DS2 siynals to optical DS2 signals 30 and injects them onto the fiber optic cables 24. Since the DS2 communications unit 10 is an end-to-end system, each converteL module at one end has a counterpart lQ at the other end. This counterpart converter module 28 includes an optical to electrical converter 32 and demultiplexer 34. Each end 12, 14 has a ~'private~
communications channel with the other end to allow status message transfer of framed message 50. This private communication occurs over the X-bit 60 of the DS2 formatted signal 30, Fig 2.
Fig. 2 shows components of the DS2 formatted signal 30. The DS2 formatted signal 30 has a bit-rate of 6.312 Megabits per second (Mb/s). This bit-rate was chosen to allow for DS2 framing bits 62, information bits 64, stuff bits 66, and an overhead bit, called the X-bit 60.
The X-bit occurs every 186 microseconds in the DS2 signal 30. Please refer to BellCore document TR-TSY-00499, hereby incorporated by reference, for further details. Because the fiber optic output of a converter module can only be connected to the fiber optic input of other converter modules, the X~blt 60 in ~he DS2 formatted signal 30 can be used in a specified fonnat. Thus, the X-bit 60 is u~ed as an end-to-end pri~ate communications channel 40.
Fig. 3 discloses a block diagram of the private communications channel 40 be~ween ~ransmi~ting end 12 and receiving end 14. ~n asynchronous communications protocol 52, running at 2400 baud, is imposed on the X-bit 60 of the DS2 formatted signal to provide this communications channel 40. The asynchronous communlcations protocol 52 overlaid on the X-bit 60 results in in~ormation transfer bytes 56.
These information transfer bytes 56 have the following parameters: eight bits; one stop bit; no parity bit; one start bit; 2400 bits/second. The message transfer in the end-to-end private communications channel 40 occurs in higher level structures called frames 50 which include four information transfer bytes 56 therein. This framing technique 54 (derived from IBM~s BiSynchronous forma~) prepends and appends certain control bytes 58,(Fig. 4)to the information transfer bytes 56. The framing technique 54 also appends two bytes of error checking information to the information by'ces, generally a cyclic redundancy check (CRC) 59, Fig 4.
Fig. 4 shows in block form frame 50, which is the message transferred on private communications channel 40 in frame fonmat. Frames 50 include control bytes DLE, STX, and ETX (per ASCII standards). These control bytes 54 _ .. . .. ..
~9, ~7 -3:~
frame information byte~ 56 of the message and allow transmission of all 256, 8 bit codes. Also included .in frame 50, as indicated previously, are two bytes of cyclic redundancy checks 59 for error checking.
Although the present invention has been described above in a preferred form, those skilled in the art will readily appreciate that various modifications may be made to it without departing from the spirit and scope of the invention, as bounded by the claims of the application itself.
. .
,3 ~hat is claimed is~
1. A DS2 end-to-end communications unit, comprising:
conversion means for converting a plurality of electrical signals to a DS2 formatted signal and for reconverting said DS2 formatted signal, said DS2 formatted signal having an X-bit; and an asynchronous protocol overlaid on said X-bit o~ said DS2 formatted signal to provide a priva~e communications channel for transport of information bytes thereon.
2. A DS2 communications unit according to claim 1 further comprising framing means for framing said information bytes, said framing means including prepending and appending control bytes and error-checking bytes to said information bytes.
.. . . ... .
Claims (9)
1. In an end-to-end communications unit for transmission of a DS2 formatted signal including an X bit therein, a signalling system comprising an asynchronous protocol imposed on said X-bit of said DS2 formatted signal to form information bytes and provide a private communications channel allowing for transmission of said information bytes thereby.
2. A signalling system according to claim 1, wherein said asynchronous protocol imposed on said X-bit includes a plurality of bits, said plurality of bits including a stop bit and a start bit for each information byte transmitted.
3. A signalling system according to claim 2, wherein said asynchronous protocol runs at approximately 2400 bits per second.
4. An end-to-end fiber optic communications unit for converting a plurality of T1 lines into a DS2 formatted signal for transmission over fiber, said DS2 formatted signal having an X-bit therein, said unit including a private communications channel, comprising:
conversion means for multiplexing a plurality of said T1 lines into said DS2 formatted signal onto a fiber at a first end of said end-to-end system and for demultiplexing said DS2 formatted signal at a second end of said end-to-end system, said conversion means including means for imposing an asynchronous protocol on said X-bit of said DS2 formatted signal to provide a private communications channel, said private communications channel allowing transmission of information bytes resulting from said asynchronous protocol imposed on said X-bit of said DS2 formatted signal, said conversion means further including means for extracting the information bytes from said private communications channel.
conversion means for multiplexing a plurality of said T1 lines into said DS2 formatted signal onto a fiber at a first end of said end-to-end system and for demultiplexing said DS2 formatted signal at a second end of said end-to-end system, said conversion means including means for imposing an asynchronous protocol on said X-bit of said DS2 formatted signal to provide a private communications channel, said private communications channel allowing transmission of information bytes resulting from said asynchronous protocol imposed on said X-bit of said DS2 formatted signal, said conversion means further including means for extracting the information bytes from said private communications channel.
5. A communications unit according to claim 4, wherein said asynchronous protocol imposed on said X-bit includes a plurality of bits, said plurality of bits including a stop bit and a start bit for each information byte transmitted.
6. A communications unit according to claim 5, wherein said asynchronous protocol runs at approximately 2400 bits per second.
7. A method for X-bit signalling in an end-to-end communications unit of a DS2 formatted signal including an X-bit therein, comprising the steps of:
converting a plurality of T1 signals to said DS2 formatted signal at a first end of said end-to-end communications unit;
imposing upon said X-bit of said DS2 formatted signal an asynchronous communications protocol resulting in information bytes and providing a private communication channel for allowing transmission of said information bytes;
transmitting said information bytes via said private communications channel in said DS2 formatted signal to a second end of said communications unit;
re-converting said DS2 formatted signal at said second end of said communications unit; and extracting said information bytes from said private communications channel.
converting a plurality of T1 signals to said DS2 formatted signal at a first end of said end-to-end communications unit;
imposing upon said X-bit of said DS2 formatted signal an asynchronous communications protocol resulting in information bytes and providing a private communication channel for allowing transmission of said information bytes;
transmitting said information bytes via said private communications channel in said DS2 formatted signal to a second end of said communications unit;
re-converting said DS2 formatted signal at said second end of said communications unit; and extracting said information bytes from said private communications channel.
8. A method according to claim 7, wherein said asynchronous communications protocol includes a plurality of bits, said plurality of bits including a stop bit and a start bit for each information byte transmitted.
9. A method according to claim 8, wherein said asynchronous communications protocol runs at approximately 2400 bits per second.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US608,132 | 1984-05-07 | ||
| US60813290A | 1990-11-01 | 1990-11-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2050751A1 true CA2050751A1 (en) | 1992-05-02 |
Family
ID=24435183
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002050751A Abandoned CA2050751A1 (en) | 1990-11-01 | 1991-09-05 | Asynchronous x-bit signalling in ds2 signal format |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2050751A1 (en) |
-
1991
- 1991-09-05 CA CA002050751A patent/CA2050751A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |