TECHNICAL REPORT
`
`
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`
`TR-013
`Interfaces and System Configuration for ADSL Central
`Office
`Issue: 1.0
`Issue Date: January 1999
`
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`© The Broadband Forum. All rights reserved.
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`Exhibit 1024, Page 1
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`Interfaces/System Configuration for ADSL: Central Office
`
`TR-013
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`Notice
`
`The Broadband Forum is a non-profit corporation organized to create guidelines for broadband network system
`development and deployment. This Broadband Forum Technical Report has been approved by members of the
`Forum. This Broadband Forum Technical Report is not binding on the Broadband Forum, any of its members, or
`any developer or service provider. This Broadband Forum Technical Report is subject to change, but only with
`approval of members of the Forum. This Technical Report is copyrighted by the Broadband Forum, and all rights
`are reserved. Portions of this Technical Report may be copyrighted by Broadband Forum members.
`
`This Broadband Forum Technical Report is provided AS IS, WITH ALL FAULTS. ANY PERSON HOLDING A
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`
`
`By using this Broadband Forum Technical Report, users acknowledge that implementation may require licenses to
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`
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`
`The text of this notice must be included in all copies.
`
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`January 1999
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` © The Broadband Forum. All rights reserved.
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`Interfaces/System Configuration for ADSL: Central Office
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`TABLE OF CONTENTS
`
`INTRODUCTION ...............................................................................................................................................6
`1.
`STATEMENT OF PROJECT ................................................................................................................................6
`1.1
`LIST OF ACRONYMS........................................................................................................................................6
`1.2
`THE BROADBAND FORUM REFERENCE MODEL ..............................................................................................7
`1.3
`CENTRAL OFFICE SPECIFIC REFERENCE MODEL.............................................................................................7
`1.4
`RELEVANT WORK IN OTHER STANDARDS GROUPS OR FORUMS.....................................................................8
`1.5
`T1E1.4 ..................................................................................................................................................8
`1.5.1
`ITU SG15 .............................................................................................................................................8
`1.5.2
`2. TARGET APPLICATIONS AND SYSTEM IMPLICATIONS .....................................................................9
`2.1
`APPLICATIONS................................................................................................................................................9
`SYSTEM IMPLICATIONS...................................................................................................................................9
`2.2
`3. ATU-C / SPLITTER INSTALLATION ..........................................................................................................10
`3.1
`GENERAL CONSIDERATIONS.........................................................................................................................10
`POTS SPLITTER............................................................................................................................................10
`3.2
`3.2.1
`Splitter Definition ...............................................................................................................................10
`3.2.2
`POTS Splitter Characteristics .........................................................................................................11
`ATU-C / SPLITTER CONFIGURATIONS ..........................................................................................................11
`3.3
`3.3.1
`POTS Splitter Located with ATU-C ....................................................................................... 13
`3.3.2
`POTS Splitter Located near ATU-C ...................................................................................... 14
`3.3.3
`POTS Splitter Located on MDF............................................................................................. 15
`3.3.4
`POTS Splitter Located Near MDF......................................................................................... 16
`3.3.5
`ATU-C Remote...................................................................................................................... 17
`3.3.6
`POTS Splitter Located Near PSTN Switch ........................................................................... 18
`Integrated POTS and ADSL Line Card ................................................................................. 19
`3.3.7
`ATU-C/SPLITTER CONFIGURATION COMPLEXITY COMPARISON..................................................................20
`3.4
`4.
`INTERFACE WIRING CONSIDERATIONS ...............................................................................................21
`4.1
`WIRING CONSIDERATIONS............................................................................................................................21
`
`ANNEX A
`
`ANNEX B
`
`
`THE BROADBAND FORUM SYSTEM REFERENCE MODEL ..........................................22
`
`THE POTS SPLITTER................................................................................................................24
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`January 1999
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`
`LIST OF FIGURES
`
`FIGURE 1. CENTRAL OFFICE SPECIFIC REFERENCE MODEL ............................................................................................7
`FIGURE 2. BASELINE POTS MDF CONFIGURATION .....................................................................................................10
`FIGURE 3. POTS SPLITTER LOCATED WITH ATU-C .....................................................................................................13
`FIGURE 4. POTS SPLITTER LOCATED NEAR ATU-C.....................................................................................................14
`FIGURE 5. POTS SPLITTER LOCATED ON MDF (HORIZONTAL SIDE SHOWN)..............................................................15
`FIGURE 6. POTS SPLITTER LOCATED NEAR MDF.......................................................................................................16
`FIGURE 7. ATU-C REMOTE..........................................................................................................................................17
`FIGURE 8. POTS SPLITTER LOCATED NEAR PSTN SWITCH ........................................................................................18
`FIGURE 9. INTEGRATED POTS AND ADSL LINE CARD ...............................................................................................19
`FIGURE 10. BROADBAND FORUM SYSTEM REFERENCE MODEL....................................................................................22
`FIGURE 11. IDEALIZED CENTRAL OFFICE POTS SPLITTER.............................................................................................24
`FIGURE 12. IDEALIZED REMOTE POTS SPLITTER .........................................................................................................24
`FIGURE 13 TYPICAL “HALF-RINGER” USED IN U.S. IN THE NID ..................................................................................26
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`Interfaces/System Configuration for ADSL: Central Office
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`TR-013
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`ABSTRACT:
`
`This project describes interfaces and system configurations for ADSL at the central office (wiring center). It covers
`electrical interfaces, connectorization, and wiring topologies with emphasis on POTS splitter issues, locations of
`equipment, and inter-equipment connections.
`
`Where possible, technical information will be obtained by reference to existing specifications, and by liaison to
`technical standards groups.
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`January 1999
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`Interfaces/System Configuration for ADSL: Central Office
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`TR-013
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`1. Introduction
`
`1.1 Statement of Project
`
`This project intends to define electrical interfaces, connectorization, and wiring topology for ADSL central office
`installations. Where possible, technical information will be obtained by reference to existing specifications and by
`liaison to technical standards groups. The work on this project is limited to addressing the logical interfaces
`necessary to support connection of the ATU-C to the outside plant (OSP) and PSTN (if used). This work is
`compatible with both conventional and splitterless (at the ATU-R) ADSL. Thus, the configuration at the central
`office is independent of the configuration at the customer premises.
`
`List of Acronyms
`1.2
`AC.............................. Alternating Current
`ADSL......................... Asymmetric Digital Subscriber Line
`ANSI.......................... American National Standards Institute
`ATM .......................... Asynchronous Transfer Mode
`ATU-C....................... Asymmetric Transmission Unit - Central (office)
`ATU-R....................... Asymmetric Transmission Unit - Remote
`CLEC......................... Competitive Local Exchange Carrier
`CO.............................. Central Office
`DC.............................. Direct Current
`DSL............................ Digital Subscriber Line
`E1............................... European digital line rate 1 (2.048Mbps)
`ETSI........................... European Telecommunications Standards Institute
`HPF............................ High Pass Filter
`ILEC .......................... Incumbent Local Exchange Carrier
`ISDN.......................... Integrated Services Digital Network
`ITU ............................ International Telecommunications Union
`kHz ............................ kilohertz
`LAN........................... Local Area Network
`LPF ............................ Low Pass Filter
`Mbps.......................... Megabits per second
`MDF .......................... Main Distribution Frame
`NID............................ Network Interface Device
`NT1............................ Network Termination 1
`OSP............................ Outside Plant
`PC .............................. Personal Computer
`POTS ......................... Plain Old Telephone Service
`PSTN ......................... Public Switched Telephone Network
`SDH ........................... Synchronous Digital Hierarchy
`SONET ...................... Synchronous Optical Network
`STM........................... Synchronous Transfer Mode
`T1............................... Transmission line rate 1 (1.544Mbps)
`T1.413........................ ANSI document “Interface between Networks and Customer Installation - Asymmetric Digital Subscriber Line (ADSL)
`Metallic Interface”, most recent edition
`T1E1.4 ....................... Sub-Working group .4 of ANSI Committee T1E1 (Interfaces, Power and Protection for Networks)
`U.S............................. United States
`xDSL.......................... unspecified type of Digital Subscriber Line, including (but not limited to) ADSL, HDSL, IDSL, SDSL
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`January 1999
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`The Broadband Forum Reference Model
`
`1.3
`
`The Broadband Forum System Reference Model is described in Annex A.
`
`1.4 Central Office Specific Reference Model
`
`This project utilizes the Central Office specific Reference Model as shown in Figure 1. The interfaces identified in
`this model are logical interfaces and not necessarily physical implementations. Physical topology and
`implementation are covered in later sections.
`
`Scope of work for current project
`
`VA
`
`U-C2
`
`U-C
`
`ATU-C
`
`ATU-C
`
`ATU-C
`
`ATU-C
`
`ACCESS
`NODE
`
`SPLITTER
`
`LOOP
`
`POTS-C
`
`PSTN
`
`
`
`ATU-C:
`
`U-C:
`
`U-C2:
`
`Figure 1. Central Office Specific Reference Model
`ADSL Transmission Unit at the network end. The ATU-C may be integrated within an
`Access Node.
`Interface between Loop and POTS Splitter on the network side. Defining both ends of the
`Loop interface separately arises because of the asymmetry of the signals on the line.
`Interface between POTS Splitter and ATU-C. Note that at present ANSI T1.413 does not
`define such an interface and separating the POTS Splitter from the ATU-C presents some
`technical difficulties in standardizing the interface.
`Interface between PSTN and POTS Splitter at network end.
`Public Switched Telephone Network.
`Logical interface between ATU-C and Access Node
`
`POTS-C:
`PSTN:
`VA:
`
`The central office end of a DSL link starts with the access line (twisted-pair telephone line) delineated in Figure 1
`by the U-C interface. It ends with one or more ADSL transmission units delineated in Figure 1 by the U-C2
`interface. The telephone line may or may not be used for Plain Old Telephone Service (POTS), defined as analog
`POTS delivered over the metallic pair, and not derived from the ADSL signal, as well as ADSL. If it is used for
`POTS, then the central office installation must include a POTS Splitter that provides the POTS-C interface as well
`as the U-C2 interface. The ATU-C terminates the access line and provides digital signals at the VA interface.
`
`The U-C, POTS-C and U-C2 logical interfaces will be specified in this document.
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`January 1999
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`1.5 Relevant Work in Other Standards Groups or Forums
`
`1.5.1 T1E1.4
`
`ANSI committee T1E1.4 has approved text (T1E1.4 / 98-007R5) for an Issue 2 version of T1.413-1995. This text
`has been submitted for editing and future publication. The Issue 2 version of T1.413 includes detailed splitter
`performance information, but does not address central office wiring.
`
`1.5.2 ITU SG15
`
`ITU SG15 is progressing work on a number of draft recommendations on ADSL. These documents (G.992.2
`[formerly G.lite], G.992.1 [formerly G.dmt], etc.) include detailed splitter performance information, but do not
`address central office wiring.
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`January 1999
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`2.
`
`Target Applications and System Implications
`
`2.1 Applications
`
`The primary applications supported by ADSL will be POTS and data communications and video on demand. These
`applications require the transport of packet data, ATM data or bit synchronous data.
`
`In some cases, POTS may not be used, in which case the POTS splitter and POTS-C interface may not be needed.
`
`
`2.2 System Implications
`
`Serving these applications involves routing a subscriber’s POTS service through a central office modem to combine
`it with the ADSL signals. The different configurations shown in this document have distinct cabling, cross-connect,
`and hardware configurations. Local practices will determine which configuration best meets the needs of the service
`provider.
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`ATU-C / Splitter Installation
`
`3.
`
`
`3.1 General Considerations
`
`In the telephone company central office the access line is terminated on the protected side of the MDF, commonly
`referred to as the vertical side. The telephone equipment connections are presented on terminal blocks mounted on
`the distribution side of the MDF, commonly referred to as the horizontal side. For normal POTS service, a cross-
`connection is made between a protector block and a line terminal block in order to establish the connection between
`the PSTN and the access line.
`
`
`PROTECTOR
`CONNECTOR
`
`MDF
`
`TERM
`BLK
`
`PSTN
`
`LOOP
`
`SINGLE TWISTED PAIR
`25 OR 32 PAIR CABLE
`100 PAIR CABLE
`
`Figure 2. Baseline POTS MDF Configuration
`
`
`
`
`When ADSL and POTS services are combined on the same access line, the POTS signal must be separated from the
`ADSL signal before the cross-connection to the line terminal block is made. The location of the POTS Splitter can
`have a significant impact on the number of MDF terminal blocks and the quantity of cable that must be used to
`facilitate the necessary connections. Moreover, the POTS Splitter circuit design depends on whether the only
`requirement is to remove the ADSL signal from the POTS signal before the POTS signal is delivered to the PSTN
`switch, or whether the POTS signal must also be removed from the ADSL signal before it is delivered to the
`ATU-C. In the first case, a low pass filter may be the only requirement. In the second case, both low pass and high
`pass filters may be required.
`
`3.2 POTS Splitter
`
`3.2.1 Splitter Definition
`
`The POTS Splitter, for the purposes of this project, is considered to be the device that splits the POTS signals from
`the ADSL signals thus preventing the ADSL signals from reaching the telephone equipment. It may also prevent
`the POTS signals from reaching the ATU-C. The POTS Splitter may be active or passive, comprise the low pass
`filter (LPF) section only, or comprise the LPF section and the high pass filter (HPF) section. The LPF section
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`contains circuitry that passes POTS frequencies (approximately 0 to 4 kHz1) to and from the telephone equipment
`and blocks the ADSL signal. The POTS Splitter (LPF only variation) may allow for the complete spectrum,
`including the ADSL signals (above approximately 20 kHz) to pass to the ATU-C.
`
`In the case that an HPF section is needed to prevent low frequency, high level POTS signals from entering the
`ATU-C front end components, the circuitry may be included in, and be considered part of, the ATU-C. HPF
`circuitry may be included as part of POTS Splitter (along with the LPF) when it is necessary to provide access to the
`ADSL signals while preventing access to the POTS signals. This may occur when ADSL signal access must be
`given to an alternate service provider by an incumbent service provider.
`
`The ATU-C manufacturer should not assume that the HPF has been implemented external to its equipment. Even
`when the HPF is included as part of the POTS Splitter, the possibility of noise ingress may require another HPF at
`the ATU-C, if the ATU-C and the POTS Splitter are not located near one another. It is recommended that all
`manufacturers of ATU-C equipment plan on explicitly implementing the appropriate HPF.
`
`See Annex B for additional details.
`
`
`3.2.2 POTS Splitter Characteristics
`
`POTS Splitter electrical, environmental and physical characteristics will not be specified in this text. Instead the
`POTS Splitter is used as an existing system component and is shown along with the other system components such
`as ATU-C and wiring to comprise the configurations detailed in sections to follow.
`
`The current ANSI standard, T1.413-1995, and the pending Issue 2 version of this standard (T1E1.4 / 98-007R5)
`specify the loop conditions under which the splitter and ADSL must be able to operate without causing significant
`degradation to the POTS signal. These characteristics will be incorporated in this document by reference. Work by
`other groups (such as ETSI, ITU, UAWG, etc.) applicable to POTS Splitters will be addressed when available.
`
`
`3.3 ATU-C / Splitter Configurations
`
`Various central office POTS Splitter configurations are discussed in the following sections.
`
` •
`
` POTS Splitter Located with ATU-C
`• POTS Splitter Located near ATU-C
`• POTS Splitter Located on MDF
`• POTS Splitter Located near MDF
`• ATU-C Remote
`• POTS Splitter Located near PSTN Switch
`•
`Integrated POTS and ADSL Line Card
`
` A
`
` brief introduction for each configuration is presented along with a figure depicting both logical and physical
`attributes (topology & implementation).
`
`This is followed by a list of advantages and disadvantages for each configuration. These advantages and
`disadvantages can be utilized in order to choose the configuration that best suits the needs of any particular
`deployment.
`
`
`
`
`1 Out of band signaling tones may need to be passed in some applications (to be defined outside the scope of this
`document).
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`January 1999
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`A suggested list of criteria is provided below. When used in conjunction with specific priorities or importance
`values (as determined by the provider) these criteria would allow a selection of the best configuration to be made for
`any particular ADSL system deployment.
`
`Criteria:
`Installation complexity
`Central office layout
`MDF capacity
`MDF maintenance complexity
`Separate service provision requirements (Ownership and/or regulatory requirements that may be country
`specific)
`Failure effects of Splitter, ATU-C
`Testing and Maintenance -- Splitter, ATU-C
`Type of Splitter -- Active or Passive
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`January 1999
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`3.3.1 POTS Splitter Located with ATU-C
`
`Figure 3 shows a configuration with the POTS Splitter combined with the ATU-C, e.g., on the same circuit card. In
`this configuration, the ATU-C and POTS Splitter are located a significant distance from the MDF. The location
`could be in a separate room from the MDF, on a separate floor in the same building or in a separate building.
`
`
`
`PROTECTOR
`CONNECTOR
`
`LOOP
`
`MDF
`
`TERM
`BLK
`
`TERM
`BLK
`
`TERM
`BLK
`
`PSTN
`
`ATU-C
`
`LPF
`HPF
`
`SPLITTER
`
`SINGLE TWISTED PAIR
`25 OR 32 PAIR CABLE, TYPICAL
`100 PAIR CABLE, TYPICAL
`
`Figure 3. POTS Splitter Located with ATU-C
`
`
`
`
`Advantages:
`• Low susceptibility to high frequency interference between POTS Splitter and ATU-C.
`• Power for active POTS Splitter readily available.
`
`Disadvantages:
`• Removal of the ATU-C circuit for servicing could interrupt POTS.
`• The POTS signal must be returned to the MDF from the ATU-C shelf using a second cable.
`• Separate access to the ADSL signal, without access to the POTS signal, is not available at the MDF.
`•
`If customer moves, jumper must be returned to PSTN line terminal block to maintain soft dial tone to recover
`use of ATU-C.
`• May limit equipment rack density, especially if POTS is not provided.
`
`January 1999
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`Exhibit 1024, Page 13
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`3.3.2 POTS Splitter Located near ATU-C
`
`Figure 4 shows a configuration with the POTS Splitter close to the ATU-C, e.g., in a shelf on the same equipment
`rack. In this configuration, the ATU-C and POTS Splitter are located a significant distance from the MDF. The
`location could be in a separate room from the MDF, on a separate floor in the same building or in a separate
`building.
`
`
`PROTECTOR
`CONNECTOR
`
`MDF
`
`TERM
`BLK
`
`TERM
`BLK
`
`TERM
`BLK
`
`PSTN
`
`EQUIPMENT RACK
`
`ATU-C
`
`HPF
`
`LPF
`
`SPLITTER
`
`SINGLE TWISTED PAIR
`25 OR 32 PAIR CABLE, TYPICAL
`100 PAIR CABLE, TYPICAL
`
`
`Figure 4. POTS Splitter Located near ATU-C
`
`LOOP
`
`
`
`
`Advantages:
`• Power for active POTS Splitter readily available.
`• Removal of the ATU-C card does not affect POTS service.
`• Low susceptibility to high frequency interference between POTS Splitter and ATU-C.
`• POTS Splitter is optional if data-only service is provided.
`
`Disadvantages:
`• The POTS signal must be returned to the MDF from the POTS Splitter using a second cable.
`• Separate access to the ADSL signal, without access to the POTS signal, is not available at the MDF.
`•
`If customer moves, jumper must be returned to PSTN line terminal block to maintain soft dial tone to recover
`use of ATU-C.
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`January 1999
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` © The Broadband Forum. All rights reserved.
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`Exhibit 1024, Page 14
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`3.3.3 POTS Splitter Located on MDF
`
`Figure 5 shows a configuration with the POTS Splitter separate from the ATU-C. The POTS Splitter is contained in
`a housing mounted on the MDF (horizontal or vertical side). The housing also provides the POTS Splitter
`connections to the Loop, ATU-C and PSTN. The ATU-C and the PSTN switch are located a significant distance
`from the MDF.
`
`
`
`PROTECTOR
`CONNECTOR
`
`LOOP
`
`MDF
`
`TERM
`BLK
`
`LPF
`
`HPF
`(OPTIONAL)
`
`SPLITTER
`
`PSTN
`
`ATU-C
`
`HPF
`
`SINGLE TWISTED PAIR
`25 OR 32 PAIR CABLE, TYPICAL
`100 PAIR CABLE, TYPICAL
`
`Figure 5. POTS Splitter Located on MDF (Horizontal Side Shown)
`
`
`
`
`Advantages:
`• Removal of the ATU-C card does not affect POTS service.
`• One cable connection is required between the ATU-C and the MDF.
`•
`Incorporation of an optional high pass filter provides separate access to the ADSL signal at the MDF without
`access to the POTS signal.
`• Provides ability to maximize ATU-C equipment rack density.
`• POTS Splitter is optional if data-only service is provided.
`
`Disadvantages:
`• MDF conditions may constrain the number and size of POTS Splitters.
`
`January 1999
`
`
` © The Broadband Forum. All rights reserved.
`
`
`
`
`
`
`
` 15
`
`Dish
`Exhibit 1024, Page 15
`
`

`
`Interfaces/System Configuration for ADSL: Central Office
`
`TR-013
`
`3.3.4 POTS Splitter Located Near MDF
`
`Figure 6 shows a configuration with the POTS Splitter separate from the ATU-C. The POTS Splitter mounts in an
`equipment rack near the MDF while the ATU-C and the PSTN switch are located a significant distance from the
`MDF. The POTS Splitter connections to the Loop, ATU-C and PSTN are centralized at a single terminal block via
`connectorized cables.
`
`
`MDF
`
`PROTECTOR
`CONNECTOR
`
`TERM
`BLK
`
`TERM
`BLK
`
`PSTN
`
`ATU-C
`
`HPF
`
`LPF
`
`HPF
`(OPTIONAL)
`
`SPLITTER
`
`SINGLE TWISTED PAIR
`25 OR 32 PAIR CABLE, TYPICAL
`100 PAIR CABLE, TYPICAL
`
`LOOP
`
`
`
`
`Figure 6. POTS Splitter Located Near MDF
`
`
`Advantages:
`• Removal of the ATU-C card does not affect POTS service.
`• High density, e.g., 32 circuit, terminal blocks may be used to provide POTS Splitter connections.
`• One long cable is required between the ATU-C and the MDF.
`•
`Incorporation of an optional high pass filter provides separate access to the ADSL signal at the MDF without
`access to the POTS signal.
`• Provides ability to maximize ATU-C equipment rack density.
`• POTS Splitter is optional if data-only service is provided.
`
`Disadvantages:
`• A separate equipment rack is required to house the POTS Splitters.
`• Two or three cables are required to connect the POTS Splitters to the MDF terminal block.
`
`January 1999
`
`
` © The Broadband Forum. All rights reserved.
`
`
`
`
`
`
`
` 16
`
`Dish
`Exhibit 1024, Page 16
`
`

`
`Interfaces/System Configuration for ADSL: Central Office
`
`TR-013
`
`3.3.5 ATU-C Remote
`
`In Figure 7 the ATU-C is located outside the CO in a nearby building. This requires passing the ADSL signal from
`the ATU-C building to the vertical side of the MDF for lightning protection, and then to the POTS Splitter. This
`requires additional MDF wiring and additional protection compared to locating the ATU-C in the CO. Furthermore,
`the cable between the ATU-C and the MDF, and the associated connector protector must be dedicated to ADSL
`signals only. Refer to Sections 3.3.3 and 3.3.4 for discussions of POTS Splitter configurations on or near the MDF
`that are compatible with the remote ATU-C.
`
`This is an instance of “reverse ADSL”. As such, a separate cable, or special engineering, is strongly recommended
`for the facilities used between the central office and the separate building.
`
`
`
`
`SEPARATE
`BUILDING
`
`HPF
`
`ATU-C
`
`DATA
`ONLY
`
`LOOP
`
`PROTECTOR
`CONNECTOR
`
`PROTECTOR
`CONNECTOR
`
`CENTRAL OFFICE
`
`PSTN
`
`MDF
`
`TERM
`BLK
`
`HPF
`(OPTIONAL)
`
`LPF
`
`SPLITTER
`
`SINGLE TWISTED PAIR
`25 OR 32 PAIR CABLE, TYPICAL
`100 PAIR CABLE, TYPICAL
`
`
`
`Figure 7. ATU-C Remote
`
`
`Advantages:
`• Removal of the ATU-C card does not affect POTS service.
`• One long cable is required between the ATU-C and the MDF.
`•
`Incorporation of optional high pass filter provides separate access to the ADSL signal on the MDF without
`access to the POTS signal.
`• Provides ability to maximize ATU-C equipment rack density.
`• POTS Splitter is optional if data-only service is provided.
`
`Disadvantages:
`• Effective ADSL reach is reduced by the cable between the CO and the separate building and additional series
`protection elements, if used.
`• Requires additional MDF wiring and additional protection.
`• A separate cable, or special engineering, is strongly recommended for the facilities used between the central
`office and the separate building.
`
`January 1999
`
`
` © The Broadband Forum. All rights reserved.
`
`
`
`
`
`
`
` 17
`
`Dish
`Exhibit 1024, Page 17
`
`

`
`Interfaces/System Configuration for ADSL: Central Office
`
`TR-013
`
`3.3.6 POTS Splitter Located Near PSTN Switch
`
`Figure 8 shows a configuration with the POTS Splitter located near the PSTN switch in a location separate from the
`MDF. This configuration may involve the ATU-C and the POTS Splitter located in the same equipment rack. This
`configuration requires a dedicated POTS line for each ATU-C.
`
`
`PROTECTOR
`CONNECTOR
`
`MDF
`
`TERM
`BLK
`
`PSTN
`
`LPF
`
`SPLITTER
`
`HPF
`(OPTIONAL)
`
`ATU-C
`
`HPF
`
`SINGLE TWISTED PAIR
`25 OR 32 PAIR CABLE, TYPICAL
`100 PAIR CABLE, TYPICAL
`
`LOOP
`
`
`
`
`Figure 8. POTS Splitter Located Near PSTN Switch
`
`
`Advantages:
`• No additional connections required for ADSL service on MDF.
`• Low susceptibility to high frequency interference between POTS Splitter and ATU-C.
`
`Disadvantages:
`• Separate access to the ADSL signal without access to the POTS signal is not available at the MDF. Two
`additional cables between the ATU-C shelf and the MDF and an additional terminal block would be required to
`accomplish this.
`• ADSL is dedicated and MDF jumper must be moved if subscriber does not want ADSL service.
`
`January 1999
`
`
` © The Broadband Forum. All rights reserved.
`
`
`
`
`
`
`
` 18
`
`Dish
`Exhibit 1024, Page 18
`
`

`
`In