Characterization of a new copper cable for next generation DSL systems

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Kalpesh PATEL

Project Co

Project Co--ordinatesordinates

Kalpesh PATEL TELECOM ParisTech Paris, France. Maurice GAGNAIRE TELECOM ParisTech Paris, France. Sandrine FRANCOIS

Nexans Research Center Lyon, France.

Telecom

Telecom--Bretagne (Brest) Bretagne (Brest) February 14, 2008

February 14, 2008

Characterization of a new copper cable

for next generation DSL systems

Characterization of a new copper cable

for next generation DSL systems

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Agenda

1. ADSL Standards.

2. Physical layer (Copper cable technology).

3. Numerical applications.

4. Conclusion and perspectives.

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3 • Evolution of Broadband ADSL2+ Standard (1/4) D E M A N D D R IV E R S S T A N D A R D 200 Ko word document 1.5 Mo Powerpoint 10 Mo Audio File 700 Mo Video file 25s 3 min 12 s 21 min 20 s ~1 day <1s 6 s 40 s 46 min 40 s <1s ~1 s 8 s 9 min 20 s ASSOCIATED FREQUENCY PLAN 34 KHz 0 to 1.1 MHz 0 to 2.2 MHz 0 to 12 MHz Copper cable infrastructure to deliver POTS & aDSL up to 5.5km

POTS/ aDSL

Copper cable infrastructure max up to 2.5km

Fiber Optic cable infrastructure ADSL2+/

Remote aDSL

Copper cable infrastructure max up to 300m

Fiber Optic cable infrastructure VDSL

G 992.1 : ADSL G 992.3 : _{ADSL 2} G 992.5 : _{ADSL 2+} G 998 : _VDSL ITU-T BANDWIDTH /TRAFFIC SPEED REQUIRED 64 KBits/s APPLICATION _POTS ANALOGUE VOICE SERVICES 2000 2003 2004 2007 T E L E C O M IN F R A S T R U C T U R E (C A B L E S ) Central Office Subscriber Premises 1 MBits/s 2 MBits/s ADSL ADSL2 VOICE +DATA + VIDEO (MPEG2) 0 to 30 MHz >MBits/ s VDSL 2 8 MBits/s ADSL2+ VOICE +DATA + VIDEO & HDTV(MPEG4) 22 MBits/s VDSL FULL TRIPPLE PLAY 128 KBits/s 512 KBits/s ADSL/ ISDN ADSL VOICE + FAST INTERNET

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• ADSL2+, is most popular in all DSL flavour.

• ADSL stands for Asymmetric Digital Subscriber Line.

ADSL2+

• Covering 2.2 MHz bandwidth using 512 sub channel.

• Asymmetrical service, separate Upstream and Downstream

bandwidth (for data) , including POTS (voice service).

• Implemented using Fast Fourier Transform (FFT).

ADSL2+ Standard (2/4)

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• ADSL2+ (DMT) Transmission / Receiver System

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• ADSL2+ Bandwidth Allocation

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• Basic hierarchy of xDSL.

Basic Infrastructure

POTS : Plain Old Telephone Service.. DSLAM : DSL Access Multiplexer MDF = Master Distributer Frame. PBX = Private Branch eXchange. OSP = Out Side Plant.

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• Attenuation : is the function of frequency and its given by the

following equation, Basic noises for ADSL (1/3)

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• Crosstalk

• Near End Cross Talk (NEXT)

Basic noises for ADSL (2/3)

PSELFEXT is the equal level Power sum FEXT, and its derived by subtracting attenuation from PSFEXT.

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• For Shorter distance, crosstalk is the predominant factor

• For Higher distance, attenuation is the predominant factor

• In real networks, 200 meters is roughly the limit separating the

crosstalk-predominant region from the attenuation-predominant region

• Attenuation mainly depends on copper cable diameter

• Crosstalk mainly depends on cable design (Geometry of Cable)

• Key approach: improving cable design

CO = Central Office

OSP = Outside Plant (Cable) MDF = Master Distribution Frame. CPE = Customer Premise Equipment

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• Cross section of 52 pairs Classical Indoor wiring / OSP copper

cable.

Classical Telecom Cable

Core (Copper).

Insulation : 2 Insulated conductors twisted together.

Wrapping tape Polypropylene. Screen Foil ALU/PET, ALU inside.

Tin copper drains wire. RIP Cord.

Jacket : PVC Grey.

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• Cross section of 32 pairs Enhanced Indoor wiring copper cable.

Enhanced Telecom Cable by Nexans (1/2)

Given Name LAGXT = Low Attenuation Good XTalk.

Core (Copper).

Sub-bundle of 8 Pairs.

Tin copper drains wire. RIP Cord.

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• Cross section of 32 pairs Enhanced OSP copper cable.

Enhanced Telecom Cable by Nexans (2/2)

Core (Copper).

Sub-bundle of 4 Pairs.

Tin copper drains wire. Rip cord.

Jacket : PVC Grey.

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• Nexans’s Enhanced cable perform 40% better than classical

cables at 2000 m distance from CO (Central Office). Performance of Nexans Enhanced Cable

• Analytical model results are shown in the above figure using

continuous line for ADSL2+.

• Error margin around ±10 % between real measurement and

analytical modeling

Standard OSP cable Enhanced OSP by Nexans

40 % @ 2000 m

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• Nexans’s investigate that improvement on PSACR factor can

impact on cable performance.

• PSACR = Power Sum Attenuation to Crosstalk Ratio.

• Nexans’s found economical solution to improve this parameter.

• We tried math model using different level of PSACR in order to

get idea of theoretical limits of copper cables. Investigation using Math Model (1/2)

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• Following figure shows performance of cables having different

PSACR level i.e. 20, 30, 40 & 80 dB. Investigation using Math Model (2/2)

• Above figure reveals that PSACR above 40 dB, no further

improvement is obtained.

• Above 2500 m, enhanced manufacturing is useless.

PSACR _≥ 30 dB

PSACR = 20 dB

The higher PASCR, the better Crosstalk (Better Design)

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Conclusion

• Copper Cables behaves differently, below and above 200

meters

• Nexans cable reduces the impact of crosstalk compared to

existing copper wired thanks to a new cable manufacturing

• This improvement is mainly advantageous under 500 meters

• Such a distance corresponds to FTTC

• Two usage of Nexans cable:

– New copper terminations for FTTC – New private cabling systems for FTTH

• Meanwhile, improving crosstalk by better manufacturing has its

limits

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Perspectives

• Using advanced line codes and modulation techniques to

exploit the extended Shannon’s capacity,

Optimizing in Cable design.

Non-binary LDPC codes.

Iterative water-filling.

Vectored transmission.

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• Thanks a lot !

Acknowledgement

The