vectoring technology

Vectoring Technology White Paper

Issue 2.0

Date 2015-06-08

HUAWEI TECHNOLOGIES CO., LTD.

V1.0 (2012-03-12) Huawei Proprietary and Confidential

Copyright © Huawei Technologies Co., Ltd.

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Copyright © Huawei Technologies Co., Ltd. 2015. All rights reserved.

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Vectoring Technology White Paper About This Document



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About This Document

Overview

Ever since its birth in the 1990s, the rapid development of copper access technologies has

enabled digital subscriber line (DSL) to be a ubiquitous solution and become today's most

widely used and most successful fixed broadband access technology. To date, approximately

300 million DSL lines have been deployed worldwide. Meanwhile, DSL technologies have

been breaking new grounds and maturing. Services supported have diversified from the initial

pure data transmission to nowadays' Multi-Play services, including high-speed Internet access,

IPTV, VoIP, private line access, mobile backhaul, and remote power supply.

As the bandwidth requirements of the "last mile" access are booming, the "reach vs. rate"

contradiction of DSL is increasingly intensified. New services such as IPTV and mobile

backhaul are also putting higher demands on stability and reliability of DSL. Crosstalk

between twisted pairs has become the main factor that affects the rate, stability, and reliability

of the DSL line. To cope with crosstalk, the Vectoring technology comes into being. This

technology uses various methods such as crosstalk detection, compensation, and cancellation

to achieve the best DSL performance in the "crosstalk-free" environment. Moreover, this

technology fully explores potentials for copper access and meets carriers' requirements for

smooth evolution, low costs, fast time-to-market, and is manageable and controllable O&M.

This document describes the Vectoring technology, including its origin, technology principle

and standard, product implementation, application and deployment scenarios, and evolution

trend. This document also describes Huawei's contribution in the Vectoring field and

end-to-end Vectoring products and solutions.

Change History

Date Revision Version Description Author

2012-03-12 1.0 Initial official release. Li Xiaodong (ID: 162659)

Huang Lei (ID: 129620)

2015-06-08 2.0 Change description of Vectoring

across multiple equipments

Zhu Hong (ID:234131)

.

Vectoring Technology White Paper Contents



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Contents

About This Document ............................................................................................................... ii

1 Origin ......................................................................................................................................... 1

2 Vectoring Productization ........................................................................................................ 6

3 Application and Deployment ............................................................................................... 10

4 Huawei E2E Vectoring Solution ........................................................................................... 14

5 Faster and More Powerful Copper Access .......................................................................... 16

6 Summary ................................................................................................................................. 17

Vectoring Technology White Paper 1 Origin



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1 Origin

1.1 Origin

Currently, requirements for smooth evolution, low costs, fast time-to-market, and easy O&M

have become the main targets for broadband access network construction. Based on these

requirements, "Fiber-in copper-out" is blossoming in the access network. Fiber moves closer

to end users and copper plants are shorten, and FTTx network is widely introduced and

developed, including FTTC, FTTB, FTTD and FTTH. In the access network, VDSL2 is the

main access mode to face the "last mile" challenge because of its high bandwidth (ideally, 100

Mbit/s) over a short distance. However, VDSL2 requires high frequency which introduces

crosstalk between copper lines. Compared with single-pair crosstalk-free VDSL2 access, the

bandwidth on multi-pair bundle’s VDSL2 access decreases sharply as more pairs are used,

because of the increasing impact of crosstalk. The larger the number of copper lines in a

bundle of cable, the higher crosstalk is generated. Therefore, crosstalk is the main factor that

impairs the VDSL2 performance.

DSL crosstalk is divided into near-end crosstalk (NEXT) and far-end crosstalk (FEXT), as

shown in Figure 1-1. In NEXT, Tx signals are sent from the disturber pair, coupled to the

victim pair, and then are sent to the near-end Rx end of the victim pair. In FEXT, Tx signals

are sent from the disturber pair, coupled to the victim pair, and then are sent along the victim

pair, to the far-end Rx end of the victim pair. For DSL, NEXT is interference between

upstream signals and downstream signals of different pairs; FEXT is interference between

upstream signals of different pairs or between downstream signals of different pairs.

Figure 1-1 NEXT and FEXT


Issue 1.0 (2012-03-12) Huawei Proprietary and Confidential


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The VDSL2 system uses frequency division multiplexing (FDM), Tx signals of the disturber

pair and Rx signals of the victim pair use different frequencies. Therefore, the impact of

NEXT on the VDSL2 access can be eliminated or significantly decreased by using a filter.

However, FEXT signals of the disturber pair cannot be eliminated through the filter because

they have the same frequency as the normal Rx signals of the victim pair. In addition, VDSL2

requires short transmission distance (usually within one kilometer) and high frequency (30

MHz at highest). As a result, FEXT in VDSL2 is more serious than other traditional DSL

technologies and becomes the main factor that affects its performance. FEXT leads to

signal-to-noise ratio (SNR) decrease, which reduces the line data rate or increases the bit error

rate (BER), or potentially resynchronization, severely affecting system stability and customer

experience.

To cope with FEXT, the dynamic spectrum management (DSM) technology has been widely

used to adjust Tx signals of DSL lines in the same bundle to balance the DSL performance

and stability. There are four levels from level 0 to level 3 in the development of the spectrum

management technology as shown in Figure 1-2. Level 0–level 2 partially decrease FEXT and

optimize DSL performance and stability by managing spectrum of Tx signals of single-pair

DSL lines or multi-pair DSL lines. However, FEXT cannot be canceled completely.

Figure 1-2 Development of the spectrum management technology

To fully cancel FEXT from VDSL2, ITU-T formulates the Vectoring technology standard,

a.k.a. DSM level 3. Vectoring technology cancels most of VDSL2’s mutual FEXT, thus

improving VDSL2 performance obviously.

1.2 Technology Principle and Standard The principle of vectoring technology is depicted in Figure 1-3. According to communications

principles, Rx signal Yn is the product of Tx signal Xn and Channel transmission function Hnn.

For simplicity, this document uses the upstream direction (from the CPE to CO) of two DSL

lines as an example for analysis. As shown in the following figure, in ideal transmission




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without crosstalk, Yn = Hnn*Xn. With FEXT, distortion h12*x2 is added to y1 and distortion

h21*x1 is added to y2.

In the upstream direction (the CO end), the Vectoring system uses the FEXT decoder to

extract the FEXT information, and then removes the FEXT information from the original Rx

signals to get the nearly crosstalk-free performance. In the downstream direction, the CPE

feeds back the FEXT information to the CO in the way negotiated between the CPE and the

CO, and then the CO uses the FEXT pre-coder to pre-code the FEXT information to the

normal Tx signals. After that, the pre-coded signals and the FEXT information are canceled in

transmission and the Rx end receives the correct information almost without crosstalk.

Figure 1-3 Vectoring technology principles

To accelerate the application of Vectoring, ITU-T formulated the G.993.5 standard in 2010

and amended the existing standards including G.993.2, G.994.1, and G.997.1. The Broadband

Forum (BBF, formally known as DSL Forum) focuses on Vectoring's performance, test,

interoperability, and O&M. Moreover, China and North America may also formulate

proprietary Vectoring standards or specifications.

Table 1-1 describes the International standards and specifications about Vectoring.

Table 1-1 International standards and specifications about Vectoring

Standard Organization

Standard ID

Standard Description First Release

Vectoring Amendment

ITU-T

G.993.5

(G.vector)

Self-FEXT cancellation

(Vectoring) for use with

VDSL2 transceivers

2010 Amd 1

G.993.2

(G.vdsl)

Second-generation VDSL

transceivers 2006 Amd 5, Amd 6




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G.994.1 (G.hs)

Handshake procedures for DSL transceivers

1999 Amd 5, Amd 8

G.997.1

(G.ploam)

Physical layer

management for DSL transceivers

1999 Amd 1, Amd 3,

Amd 4

BBF

WT-249

Testing of G.993.5

self-FEXT cancellation

(Vectoring) for use with

VDSL2 Transceivers

2011 -

TR-252

issue 2

xDSL

protocol-independent management model

- -

1.3 Prospects

Theoretically, Vectoring can fully cancel FEXT impacts on the VDSL2 performance, and

achieve higher data rate over the same distance, or larger coverage with the same data rate.

The curves shown in figure 1-4 represent the "reach vs. rate" performance of VDSL2 (17a

profile, B8-11 PSD mask, line diameter 0.4 mm) in the downstream direction as an example.

From the figure, it can be seen that the VDSL2 performance in the crosstalk-free environment

is 50–90% higher than which in the FEXT environment without Vectoring. The result shown

in Figure 1-4 also indicates that the denser the lines and the higher the number provisioning

rate, the stronger the FEXT. Therefore, vectoring technology plays an important role in the

improvement of VDSL2 performance. The VDSL2 performance in the upstream direction is

similar to that in the downstream direction.

Figure 1-4 Performance comparison for VDSL2 with and without Vectoring

Vectoring, as a new generation technology for improving the performance, is compatible with

the other DSL technologies, including retransmission (G.inp), bonding, network time




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reference (NTR), seamless rate adaption (SRA), and bit swap (BS), etc. With all these

technologies, Vectoring can be flexibly used in various scenarios, such as residential user

access, commercial user access, mobile backhaul, and remote access site backhaul.

Figure 1-5 Vectoring application scenarios

Vectoring Technology White Paper 2 Vectoring Productization



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2 Vectoring Productization

2.1 Challenges

The Vectoring system jointly processes signals of all VDSL2 pairs in a Vectoring group

(jointly sending signals in the downstream direction and jointly receiving signals in the

upstream direction) to cancel self-FEXT and improve performance.

Compared with the VDSL2 system reference model, the Vectoring system adds the vectoring

control entity (VCE) and the interface between the VTU-Os and the ME (Management Entity),

as shown in red in Figure 2-1. Inside the AN, the ME further conveys the management

information for a particular line (over an interface here called ε-m) to the vectoring control

entities (VCEs) of the Vectoring group that line belongs to. Each VCE controls a single

vectored group, and controls VTU-O-n (connected to line n in the vectored group) over an

interface here called ε-c-n. Pre-coder data are exchanged between VTU-O-n1 and VTU-O-n2

over an interface here called ε-n1-n2. Figure 2-1 shows the first pair in the Vectoring group.

Figure 2-1 Reference model of the Vectoring system [ITU-T G.993.5]




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The main challenge for Vectoring productization is how to transmit and process the mass data

with high reliability and easy O&M. Specifically, the main challenge is the ε-n1-n2 interface.

A pair in the N-pairs Vectoring group exchanges the pre-coded data with another N - 1 pair.

When the Vectoring system capacity increases, huge amounts data need to be exchanged.

Here, the 48-port Vectoring line card is used as an example. The bandwidth for transmitting

the pre-coded data will be 20-30 Gbit/s. If an AN contains multiple Vectoring line cards, the

bandwidth will be hundreds of Gbit/s, which is close to or beyond the data transmission

volume of an optical access equipment.

The mass amount of data for Vectoring will also cause big problem for Vectoring across

multiple equipments. There is no standard for the ε-n1-n2 interface as mentioned above.

Different chipset vendor or equipment vendor can have different interface and protocol

between line card and VP card. Another issue is for Vectoring across multiple equipments, it

needs a centralized Vectoring Engine shelf to collect all the line data in different equipment.

Again there is no standard for the interface between Vectoring Engine shelf and equipment

shelf. Another issue is such interface itself requires very high speed and same short latency

between different equipment. Currently Huawei can support Vectoring across two equipments

using a 5-meter short cable or 30-meter fiber to support a very high speed interface with

Huawei internal protocol. This makes it possible for two operators to deploy Vectoring using

the same equipment from Huawei. It’s difficult for equipment from different vendor due to the

different interface and protocol. For more than two equipments, the main challenge is on the

high capacity Vectoring master shelf. It’s still technically quite challenge to get the powerful

chipset to handle multiple high speed interfaces and do the centralized Vectoring processing.

Another issue is on the political and regulation side, for real deployment, which operator

should own and pay for the Vectoring master shelf and how to guarantee the fair process

between master shelf and different access shelf.

2.2 Consideration

Similar to the Vectoring system reference model, the Vectoring product need integrate

Vectoring process (VP) parts and related interfaces based on the current DSLAM product.

Different carriers' networks in different countries/areas have different site models.

Accordingly, Huawei provides different specifications and has different implementation

considerations for Vectoring productization. As shown in Figure 2-2, the small-capacity

Vectoring products normally do not use independent VP card. Instead, the VP parts are

integrated in the same card with parts such as the main control unit and DSL access unit. The

medium and large-capacity Vectoring products use independent VP card, featuring

high-efficient and more-flexible processing architecture.




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Figure 2-2 Vectoring product architecture

For medium and large-capacity Vectoring products, DSL line cards and VP card communicate

with each other in a super-high speed backplane buses or external cables. Compared with the

external cable, the backplane bus will be highly reliable for hardware connection and service

assurance, facilitates cards’ interconnection, and saves space in installation, ensuring high

reliability and easy O&M of the Vectoring system.

Furthermore, the Vectoring technology speeds up the downward DSL user network interface

(UNI). Accordingly, the "speedup" challenge arises in the bandwidth of the convergence

interface on the backplane of the DSL line card, traffic processing capability of the control

card, and convergence bandwidth of the upward network node interface (NNI). This issue also

needs to be considered in Vectoring productization.

2.3 Practice

To date, Huawei has partnered with many worldwide tier-1 carriers for Vectoring deployment,

including the node level Vectoring across two equipments. The typical Vectoring test results

are shown in Figure 2-3, which are taken with some Tier-1 carrier in Europe.




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Figure 2-3 Results for lab test and live network validation

The relevant results are:

CO-based ADSL2+ has little impact on RT-based Vectoring, which can be omitted.

ADSL2+ coexisting on CO or RT has little impact on Vectoring, which is acceptable.

VDSL2 coexisting on CO or RT has serious impacts on Vectoring. One VDSL2 alien line

significantly affects Vectoring, and more VDSL2 alien lines may lead to lower Vectoring performance and BER increase, or potentially resynchronization.

Vectoring solves only the FEXT impacts on VDSL2 performance but cannot solve other line issues, such as bridge tap, mixed connection, or improper connection.

Vectoring Technology White Paper 3 Application and Deployment



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3 Application and Deployment

According to the current technology and product maturity, Huawei points out that Vectoring

application and deployment face the following TOP challenges:

Vectoring adaptation to various application scenarios

Good quality of experience (QoE) guarantee

Comprehensive support for Vectoring solutions

3.1 Vectoring Adaptation to Various Application Scenarios Having developed for more than 10 years, traditional DSL technologies including SHDSL,

SHDSL.bis, ADSL, ADSL2+, VDSL1, and VDSL2 coexist on live networks. As a new DSL

technology, Vectoring has the challenge to coexist with these traditional DSL technologies. In

addition, requirements for bandwidth, supervision institutions, carriers, and equipment

manufacturers may affect Vectoring application and deployment. Except for "E2E 100%

Vectoring capable" scenario, Vectoring faces the following adaption scenarios’ challenges:

Scenario 1. "Fiber-in copper-out" for a single carrier: In the long-term "Fiber-in

copper-out" evolution, RT based Vectoring will coexist with CO or RT based SHDSL,

SHDSL.bis, ADSL, and ADSL2+ (excluding RT based VDSL2) in the same bundle.

Scenario 2. "Loop unbundling" for multiple carriers: Including CO based local loop

unbundling (LLU) and RT based sub loop unbundling (SLU). Some countries and areas,

require LLU or even SLU. SLU has more serious requirements than LLU and therefore

Vectoring may be affected by severe VDSL2 interference from the same site or the same

bundle, or even interference among Vectoring equipments provided by different carriers

or equipment manufactures.

Scenario 3. "Reluctant coexistence" caused by interoperability between the Vectoring CO

and legacy DSL terminals: In practical Vectoring deployment, some legacy DSL

terminals may not support Vectoring. These alien lines will become disturbers interfering

with the other Vectoring lines. If the legacy terminal synchronizes in VDSL2 mode, this

scenario is similar to scenario 2.

Huawei provides a variety of processing options to meet different scenarios at various

Vectoring deployment stages, under various regulating conditions, and for carriers across

countries and regions:

In scenarios where Vectoring coexists with traditional DSL technologies such as SHDSL, SHDSL.bis, ADSL, and ADSL2+, Vectoring provides techniques such as downstream




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power back-off (DPBO) and PSD shaping to eliminate the impact of those

low-frequency interference sources such as SHDSL, SHDSL.bis, ADSL, and ADSL2+.

In scenarios where Vectoring and VDSL2 coexist over the same carrier network, Huawei

provides three coexistence policies (no coexistence, limited coexistence, and full

coexistence), which can be flexibly selected or adjusted by carriers at different Vectoring

deployment stages.

In scenarios where Vectoring on different carrier networks coexists because of LLU/SLU

regulation, Huawei provides a node level Vectoring solution across two equipments. This

solution enables coordination between Vectoring equipments of different carriers, which

are all provided by Huawei, achieving general performance optimization and stable

coexistence. However, the cross-equipment Vectoring solution between different

equipment vendors still faces interoperability challenges including architecture, protocol,

software, and hardware design and implementation. In the foreseeable short- and

mid-term, this solution cannot be realistic and practical.

For the last scenario mentioned above, Huawei recommends the virtual loop unbundling

(VLU) solution. In a typical VLU solution, only one carrier is 100% responsible for bundle

resource management, Vectoring rollouts, and Vectoring O&M to maximally achieve

performance improvement brought by Vectoring technology, while other carriers wholesale

appropriate channelized bandwidth on demand. The VLU solution achieves not only optimal

Vectoring performance but also fairness among carriers, and reduced network rollout and

O&M costs, fully guaranteeing end customers' benefits.

3.2 Good QoE Guarantee DSL QoE is mainly affected by the available bandwidth, stability, and synchronization time,

so does it for Vectoring QoE.

Many factors affect the available bandwidth of VDSL2, including self-FEXT, impulse noise,

radio frequency interference (RFI), and copper line faults. Vectoring addresses the FEXT

issue that is the most critical factor affecting VDSL2. As a result, factors hidden behind FEXT

will be exposed after Vectoring deployment. Hence, Vectoring needs to be combining

deployed with other DSL techniques such as retransmission (G.INP), seamless rate adaption

(SRA), bit swap (BS), and RFI notch, for better improving and ensuring the available

bandwidth of VDSL2.

When Vectoring is deployed, all lines in the same bundle (or in the same Vectoring group)

must coordinate with each other to process signals. If the status of a line changes

unexpectedly (for example, an unexpected disorder shutdown event occurs due to factors such

as CPE power outage, CPE failure, cable disconnection, board failure at the CO, or manual

mis-operation), the other lines in the same bundle (or in the same Vectoring group) may have

deteriorating performance (for example, increased BER or even resynchronization). This

severely affects the overall system stability.

Traditional DSL lines are activated separately, but Vectoring requires strict synchronization

and coordination for activating lines in the same bundle (or in the same Vectoring group).

Therefore, the synchronization of Vectoring lines is more time-consuming than that of

traditional DSL lines, which is more obvious in scenarios such as concurrent synchronization

of multiple lines, repeated synchronization of very few rouge lines, and synchronization in a

bundle (or a Vectoring group) that contains too many lines.

Huawei's Vectoring system provides built-in intelligent analysis and processing algorithms,

and fully leverages various DSL features to significantly expand the available bandwidth




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while controlling its reliability and synchronization time in a level comparative to traditional

DSL technologies.

3.3 Comprehensive Support for Vectoring Solution

Facing the complex application scenarios and QoE requirements, a comprehensive, mass

deployable, manageable, and controllable Vectoring solution also requires support from the

EMS, OSS, terminal management system (TMS)/auto-configuration server (ACS), DSL

expert system, and professional engineering/service.

Figure 3-1 Typical Vectoring solution and required equipment/systems

Figure 3-1 shows a typical Vectoring application scenario and required supporting

equipment/systems.

1. Vectoring DSLAM: Series Vectoring DSLAMs of different capacities are provided for

different site scales and deployment scenarios. A Vectoring DSLAM needs to support

traditional DSL technologies (such as VDSL2+, ADSL2+, and ADSL), plug-and-play of different types of CPEs, and smooth evolution of Vectoring.

2. Vectoring CPE: Includes CPEs that fully support Vectoring and Vectoring-friendly CPEs.

Normally, VDSL2 CPEs deployed on live networks can become Vectoring CPEs with

software upgrades only. (Vectoring-friendly CPEs do not affect the performance of

Vectoring lines, but the performance of lines connected to Vectoring-friendly CPEs cannot be improved.)

3. EMS: Provides graphical Vectoring O&M, which is convenient and simplified.

4. OSS: Supports Vectoring service provisioning and O&M processes, and plans and controls the schedule of Vectoring service provisioning.

5. TMS/ACS: Manages, upgrades, and maintains CPEs in a centralized manner. An ideal

environment for Vectoring deployment is where all CPEs on the entire network (or at




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least on the entire site) support Vectoring. Therefore, it is necessary to use the TMS/ACS

to upgrade VDSL2 CPEs on live networks before Vectoring deployment.

6. DSL expert system: Monitors DSL quality, evaluates and optimizes DSL performance,

and diagnoses copper line faults at a network or site level. To support Vectoring

deployment and O&M, the DSL expert system needs to provide functions specially for

Vectoring, such as pre-evaluating Vectoring performance, coordinating coexistence of

Vectoring and other DSL lines, processing combined application of Vectoring and other

DSL features, and preventing and processing Vectoring abnormalities. Providing these

functions, the DSL expert system helps achieve Vectoring capabilities that the Vectoring equipment or EMS cannot provide independently.

7. Engineering/Service: Provides services such as network planning, equipment migration,

equipment upgrade, data planning, and data migration based on Vectoring evolution/deployment scenarios and equipment models/versions on live networks.

Vectoring Technology White Paper 4 Huawei E2E Vectoring Solution



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4 Huawei E2E Vectoring Solution

4.1 Huawei's Vectoring Contribution and Innovation

As an industry-leading vendor in the access network, Huawei has continuously been making

contributions to the DSL industry. Huawei holds a large number of VIP positions, such as

chairmen and editors, in international standards-defining organizations like BBF, ATIS, and

ETSI. Huawei has grown into an influential company that contributes to standards

formulation and technical development trends. Furthermore, Huawei actively participates in

DSL standardization and works with other companies to promote DSL technologies.

In the Vectoring standards field, Huawei, as one of the two most active equipment vendors, is

the editor and main contributor of ATIS COAST-NAI crosstalk channel model. Huawei has

proposed several key technique innovations in Vectoring, including the following:

SNR-based estimation of crosstalk channels for legacy lines

Channel estimation using error feedback sampled downstream

Initialization acceleration by error scaling

In product and solution fields, Huawei has already equipped itself with independent R&D

capabilities, enabling Huawei to provide customers with E2E Vectoring products and

solutions that are more advantageous in terms of technology and cost.

4.2 Huawei E2E Vectoring Solution Huawei provides E2E Vectoring solutions covering the series Vectoring equipment at the CO,

or FTTC, FTTB, FTTD, with Vectoring CPEs, EMS, and professional supporting services.

Vectoring Technology White Paper 4 Huawei E2E Vectoring Solution



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Figure 4-1 Huawei E2E Vectoring products and solution

Huawei's Vectoring solution has the most complete series of products in the industry. Figure

4-1 illustrates a typical example of Huawei E2E Vectoring products and solution.

The MA5603T, a large-capacity Vectoring product, provides built-in high-speed Vectoring

buses and does not require extra space in an outdoor cabinet for interconnection of Vectoring

cards. This device can be deployed to mainstream large-capability Vectoring sites.

The MA5616 is a medium-capacity Vectoring product that has the highest density in the

industry. With a compact in size of 2 U height, 19-inch width and 300 mm depth, the MA5616

provides built-in high-speed Vectoring buses and Vectoring line cards, applying to mainstream

medium-capability Vectoring sites. The MA5616 supports up to 384 Vectoring lines through

cross-equipment interconnection, meeting the requirements of super-large-capacity Vectoring

sites.

For small-capacity Vectoring sites in some remote areas or sites that have requirements for

lesser coverage, shorter distance, and higher rate, Huawei provides a variety of flexible and

customized Vectoring solutions:

With the following features, the MA5611S can be directly installed in the manhole or mounted on a pole or outdoor wall in harsh environments, without the need of a cabinet:

− Fully-enclosed structure

− IP68 water-protection rating

− Operating temperature ranging from –40°C to +70°C

The pizza-box MA5623A and MA5622A are small-sized (1 U height, 19-inch width, and

300 mm depth), maximally saving installation space. They apply to the following Vectoring deployment scenarios:

− New deployment of super-small-capacity sites

− Adaptations or re-shell of legacy outdoor cabinets or intermediate distribution frames (IDFs)

− Installation in basements or corridor cabinets

Vectoring Technology White Paper

5 Faster and More Powerful Copper

Access



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5 Faster and More Powerful Copper Access

Conforming to the trend of fiber-in and copper-out in the area of broadband access,

high-speed copper access at a short distance facilitates the smooth evolution of access

networks. In the near future, the access rate per twisted pair will exceed 1Gbit/s, making

copper access a supplement or substitute solution of fiber to the premise (FTTP).

Figure 5-1 Development of copper access technologies

As shown in Figure 5-1, SuperVector or VDSL2 Annex Q will expand the frequency from

17MHz to 35MHz to enable more downstream speed. This technology can be used in the sub

loop unbundling (SLU) scenario to give more users the chance to achieve 100Mbps even

without Vectoring. G.fast with higher frequency band, it’s possible to get 1Gbps aggregated

speed within short copper distance. Besides this, Huawei is also developing 5GBB technology

using much higher frequency band targeting up to 5Gbps speed over copper.

Vectoring Technology White Paper 6 Summary



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6 Summary

Ever since its birth in the 1990s, the rapid development of copper access technologies has

enabled DSL to be a ubiquitous solution and become today's most widely used and most

successful fixed broadband access technology. As the bandwidth requirements of the "last

mile" access are booming, the inherent "reach vs. rate" contradiction, stability, reliability, and

environment adaptability of DSL face ever-formidable challenges. To conform to the trend of

smooth network evolution as "fiber-in and copper-out", the Vectoring technology has been

developed. This technology uses various methods such as probe, compensation, and

cancellation to achieve the best DSL performance in the "crosstalk-free" environment.

Moreover, this technology much further exploits the potential of copper access networks and

meets carriers’ requirements for smooth evolution, low costs, fast time-to-market, and is

manageable and controllable O&M.

The innovations of copper access technologies will continue. Vectoring working together with

other technologies such as bonding, can achieve a superfast speed over legacy copper,

enabling a cost-effective and smooth evolution of fix broadband access networks.

Vectoring Technology White Paper A Acronyms and Abbreviations



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A Acronyms and Abbreviations

A

ACS auto-configuration server

ADSL asymmetric digital subscriber line

ATIS alliance for telecommunications industry solutions

B

BBF Broadband Forum

BBU base-band unit

C

CAPEX capital expenditure

CO central office

CPE customer premises equipment

D

DLM dynamic line management

DSE disorderly shutdown event

DSL digital subscriber line

DSLAM DSL access multiplexer

DSM dynamic spectrum management

E

EMS element management system

ETSI European Telecommunications Standards Institute




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FEXT far end crosstalk

F

FTTB fiber to the building

FTTC fiber to the cabinet

FTTCurb fiber to the curb

FTTEx fiber to the exchange

FTTH fiber to the home

FTTN fiber to the node

FTTP fiber to the premise

I

INP impulse noise protection

ITU International Telecommunication Union

L

LLU local loop unbundling

M

MIMO multiple-input multiple-output

N

NEXT near end crosstalk

O

ODN optical distribution network

OFDM orthogonal frequency division multiplexing

OLT optical line terminal

OPEX operational expenditure

OSS operating and supporting system

P

PSD power spectral density




20

Q

QoE quality of experience

R

RFI radio frequency interference

RT remote terminal

S

SHDSL single-pair high-speed DSL

SLU sub loop unbundling

SNR signal-to-noise ratio

SRA seamless rate adaptation

SSM static spectrum management

T

TCO total cost of ownership

TMS terminal management system

V

VDSL very-high-speed DSL

Vectoring Vectoring (self-FEXT cancellation for use with VDSL2 transceivers)

VLU virtual loop unbundling

VN virtual noise

Vectoring Technology White Paper B References



21

B References

[1]. ITU, Self-FEXT cancellation (Vectoring) for use with VDSL2 transceivers, 2010

[2]. ITU, Very high speed digital subscriber line transceivers 2 (VDSL2), 2006

[3]. Frank Defoort, Jan Verlinden, Introduction to DSL instabilities, April, 2008

[4]. IEEE, The ITU-T's New G.vector Stand Proliferates 100 Mb/s DSL, 2010

vectoring technology

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