The SHDSL terminal model consists of the following parts:
l PDM module
– The PDM module implements functions such as: Regular code element generation and recovery, coding/decoding, modulation/demodulation, echo control, linear
equalization, and link start
– SHDSL mainly uses the trellis coded pulse amplitude modulation (TC-PAM) technology.
l PMS-TC module
The PMS-TC module implements functions such as: framing, frame synchronization scrambling, and descrambling
l TPS-TC module
The TPS-TC module implements functions such as: mapping and encapsulation of data frames, multiplexing and demultiplexing, timing alignment of multiple subscriber data channels
l I/F interface of the device at the central office – It mainly provides the ATM port.
– The ATM port is used for transmitting ATM cells over the ATM network, or according to the carried packets, transmitting Ethernet packets encapsulated by the SAR module or E1/V3.5 signals over the Ethernet network.
l I/F interface of the device on the subscriber side
It corresponds to the I/F interface of the device at the central office. In general, the I/F interface is used for providing Ethernet ports or E1/V.35 ports.
When the MA5600T/MA5603T uses the SHLB board, the TC-PAM encoding technology is shown as the following table.
Table 5-1 TC-PAM encoding technology Compliant
Standards Describes...
SHDSL R = n´64 + (i)´8, 3 ≤ n ≤ 36 and 0 ≤ i ≤ 7 (192 kbit/s to 2312 kbit/s)
The SHLB board of the MA5600T/MA5603T is based on ATM. The board provides the Ethernet port (for broadband access) or E1/V.35 port (for private line access) for connecting subscriber Module
Feature Description 5 SHDSL Access
terminals. In the upstream direction, the board is connected to the metropolitan area network (MAN) through the upstream board.
5.1.6 Acronyms and Abbreviations
Acronyms and Abbreviations
Table 5-2 Acronyms and abbreviations of the ATM SHDSL access feature Acronym/Abbreviation Full Spelling
SHDSL Single-line high speed digital subscriber line
HDSL High-speed digital subscriber line
TC-PAM Trellis coded pulse amplitude modulation
ATM Asynchronous transfer mode
Wet current 3-5 mA DC current provided for the subscriber line. (The purpose is to heat up the subscriber line to remove the gas such as steam attached to the surface of the subscriber line, thereby effectively preventing the subscriber line from corrosion and oxidation. In this way, the overall electric performance of the subscriber line is protected.)
5.2 EFM SHDSL Access
This topic describes the definition, purpose, specifications, and limitations of EFM SHDSL access feature. It also provides the glossary and the acronyms and abbreviations related to the EFM SHDSL access feature.
5.2.1 Introduction
Definition
SHDSL is an xDSL access technology, just like ADSL and VDSL. SHDSL provides the symmetric upstream and downstream rates.
EFM SHDSL integrates the advantages of the SHDSL technology and the ADSL technology.
That is, EFM SHDSL can provide traditional voice service and high rate Internet access service over common twisted pairs to meet the requirements for high definition TV service and VoD service from subscribers, which suit the last mile access for broadband to the campus.
Purpose
The utilization ratio of the EFM access service is high when the activation rates of the ATM and EFM access services are the same. Hence, if the subscriber terminal supports ATM and EFM SHDSL access services simultaneously, the EFM SHDSL access service is preferred.
Module
Feature Description 5 SHDSL Access
5.2.2 Specifications
The specifications of SHLB and SHLM are as follows:
l These boards support the single-pair and two-pair modes.
l Network timing reference (NTR) clock.
l Automatic rate adjustment according to the line conditions during initialization.
NOTE
For the two, three, or four bound ATM ports, the system does not support automatic rate adjustment.
l Reporting of the alarms and maintenance information of lines.
l PPPoE+ sub option.
l Dynamic adjustment of the specifications of the SHDSL line profile and alarm profile.
l Power-saving of the xDSL line.
l Supports wetting current.
l A maximum transmission distance of 6 km.
l Supports the configuration, modification, and query of the SHDSL line profile.
l Four modes of binding EFM or ATM ports: single-pair (two-wire), two-pair (four-wire), three-pair (six-wire), and four-pair (eight-wire).
l Line rate ranging from 192 kbit/s to 5696 kbit/s in the single-pair mode.
l Supports crosstalk cancellation.
l The line rate of the bound two, three, or four ATM/EFM ports is double, triple, or quadruple the line rate of a single port.
NOTE
l Each port in an EFM bonding group can be activated or deactivated independently. Hence, in a specific application, the line rate of the bonding group varies according to the number of the activated ports in the group.
l As defined in IEEE 802.3ah, the ratio of the maximum rate to the minimum rate in an EFM bonding group cannot exceed 4. For example, if the minimum rate is 192 kbps, the maximum rate cannot exceed 768 kbps.
l Supports F5 OAM loopback.
l Supports the configuration of ATM/EFM mode based on port.
The specifications that are supported only by the SHLM are as follows:
l Supports IMA bonding of G.SHDSL.
l Supports MELT function.
5.2.3 Availability
Hardware Support
The SHLB board supports 16 channels of ATM and PTM SHDSL service.
The SHLM board with MELT function supports 16 channels of G.SHDSL.BIS service.
License Support
The port rate measurement function and cross talk cancellation supported by the MA5600T/
MA5603T is under license. Therefore, the corresponding service is also under license.
Module
Feature Description 5 SHDSL Access
5.2.4 Reference
The following lists the reference documents of this feature:
l ITU-T Recommendation G.991.2 Annex A and Annex F.
l ITU-T Recommendation G.991.2 Annex B and Annex G.
5.2.5 Principle
Typical Application Model
The SHDSL operating principle is based on the G.991.2 (2001) standard.
Figure 5-2 Typical application model of SHDSL
User
One SHDSL system consists of an STU-C, an STU-R, and a subscriber terminal. Multiple repeaters can be added to the line between the STU-C and the STU-R.
l The STU-C provides service ports at the central office.
l The STU-R provides subscriber ports for connecting to multiple subscriber terminals.
l The SHDSL repeater unit (SRU) refers to the repeater. In ultra-long-distance transmission, it recovers signals and re-transmits signals to extend the transmission distance.
The MA5600T/MA5603T does not support repeaters.
Terminal Model
The SHDSL terminal model consists of the following parts:
l PDM module
– The PDM module implements functions such as: Regular code element generation and recovery, coding/decoding, modulation/demodulation, echo control, linear
equalization, and link start
– SHDSL mainly uses the trellis coded pulse amplitude modulation (TC-PAM) technology.
l PMS-TC module
The PMS-TC module implements functions such as: framing, frame synchronization scrambling, and descrambling
l TPS-TC module Module
Feature Description 5 SHDSL Access
The TPS-TC module implements functions such as: mapping and encapsulation of data frames, multiplexing and demultiplexing, timing alignment of multiple subscriber data channels
l I/F interface of the device at the central office – Providing ATM ports or circuit interfaces
– The ATM port is used for transmitting ATM cells over the ATM network, or according to the carried packets, transmitting Ethernet packets encapsulated by the SAR module or E1/V3.5 signals over the Ethernet network or E1 links.
– The circuit interface is used for transmitting E1 or V.35 signals directly through the time division multiplexing (TDM) network.
l I/F interface of the device on the subscriber side
It corresponds to the I/F interface of the device at the central office. In general, the I/F interface is used for providing Ethernet ports (for delivering ATM cells processed by the SAR module) or E1/V.35 ports.
Table 5-3 TC-PAM encoding technology Compliant
Standards Describes...
SHDSL R = n´64 + (i)´8, 3 ≤ n ≤ 89 and 0 ≤ i ≤ 7 (192 kbit/s to 5696 kbit/s)