la The Tour Marine Tanguy, Drive,, Brest Mumbai. (FR). Characterization of a new copper cable for next generation DSL systems Project Co-ordinates ordinates Kalpesh PATEL TELECOM ParisTech Paris, France. Maurice GAGNAIRE TELECOM ParisTech Paris, France. Sandrine FRANCOIS Nexans Research Center Lyon, France. Kalpesh PATEL Telecom-Bretagne (Brest) February 14, 2008 1
Presentation Outline Agenda 1. ADSL Standards. 2. Physical layer (Copper cable technology). 3. Numerical applications. 4. and perspectives. 2
ADSL2+ Standard (1/4) TELECOM INFRASTRUCTURE (CABLES) DEMAND DRIVERS STANDARD Evolution of Broadband ASSOCIATED FREQUENCY PLAN ITU-T Central Office SERVICES APPLICATION BANDWIDTH /TRAFFIC SPEED REQUIRED 200 Ko word document 1.5 Mo Powerpoint 10 Mo Audio File 700 Mo Video file VDSL ADSL2+/ Remote adsl POTS/ adsl 34 KHz 0 to 1.1 MHz 25s 3 min 12 s 21 min 20 s ~1 day Fiber Optic cable infrastructure Fiber Optic cable infrastructure <1s 6 s 40 s 46 min 40 s Copper cable infrastructure max up to 2.5km Copper cable infrastructure to deliver POTS & adsl up to 5.5km ANALOGUE VOICE POTS 64 KBits/s G 992.1 : ADSL VOICE + FAST INTERNET ADSL/ ISDN 128 KBits/s ADSL 512 KBits/s G 992.3 : ADSL 2 VOICE +DATA + VIDEO (MPEG2) ADSL 1 MBits/s ADSL2 2 MBits/s 0 to 2.2 MHz <1s ~1 s 8 s 9 min 20 s 2000 2003 2004 2007 3 Copper cable infrastructure max up to 300m G 992.5 : ADSL 2+ VOICE +DATA + VIDEO & HDTV(MPEG4) ADSL2+ 8 MBits/s 0 to 12 MHz VDSL 22 MBits/s G 998 : VDSL FULL TRIPPLE PLAY Subscriber Premises 0 to 30 MHz VDSL 2 >MBits/ s
ADSL2+ Standard (2/4) 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). POTS : Plain Old Telephone Service.. 4
ADSL2+ Standard (3/4) ADSL2+ (DMT) Transmission / Receiver System DMT = Discrete MultiTone 5
ADSL2+ Standard (4/4) ADSL2+ Bandwidth Allocation 6
Basic Infrastructure Basic hierarchy of xdsl. POTS : Plain Old Telephone Service.. DSLAM : DSL Access Multiplexer MDF = Master Distributer Frame. PBX = Private Branch exchange. OSP = Out Side Plant. STB = Set Top Box. 7
Basic noises for ADSL (1/3) Attenuation : is the function of frequency and its given by the following equation, 8
Basic noises for ADSL (2/3) Crosstalk Near End Cross Talk (NEXT) Far End Cross Talk (FEXT) PSELFEXT is the equal level Power sum FEXT, and its derived by subtracting attenuation from PSFEXT. 9
ADSL2+ Standard (3/3) CO OSP MDF CPE CO = Central Office OSP = Outside Plant (Cable) MDF = Master Distribution Frame. CPE = Customer Premise Equipment 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 10
Classical Telecom Cable Cross section of 52 pairs Classical Indoor wiring / OSP copper cable. Core (Copper). Insulation : 2 Insulated conductors twisted together. Wrapping tape Polypropylene. Screen Foil ALU/PET, ALU inside. Tin copper drains wire. RIP Cord. OSP = Out Side Plant. Jacket : PVC Grey. 11
Enhanced Telecom Cable by Nexans (1/2) Cross section of 32 pairs Enhanced Indoor wiring copper cable. Core (Copper). Insulation : 2 Insulated conductors twisted together. Sub-bundle of 8 Pairs. Wrapping tape Polypropylene. Screen Foil ALU/PET, ALU inside. Tin copper drains wire. RIP Cord. Jacket : PVC Grey. Given Name LAGXT = Low Attenuation Good XTalk. 12
Enhanced Telecom Cable by Nexans (2/2) Cross section of 32 pairs Enhanced OSP copper cable. Core (Copper). Insulation : 2 Insulated conductors twisted together. Sub-bundle of 4 Pairs. Wrapping tape Polypropylene. Screen Foil ALU/PET, ALU inside. Tin copper drains wire. Rip cord. Given Name OSP 54. Jacket : PVC Grey. 13
Performance of Nexans Enhanced Cable Nexans s Enhanced cable perform 40% better than classical cables at 2000 m distance from CO (Central Office). Enhanced OSP by Nexans @ 2000 m 40 % Standard OSP 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 14
Investigation using Math Model (1/2) 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. 15
Investigation using Math Model (2/2) Following figure shows performance of cables having different PSACR level i.e. 20, 30, 40 & 80 db. PSACR 30 db PSACR = 20 db The higher PASCR, the better Crosstalk (Better Design) Above figure reveals that PSACR above 40 db, no further improvement is obtained. Above 2500 m, enhanced manufacturing is useless. 16
Summary at a glance (1/2) s 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 17
Summary at a glance (2/2) 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. 18
Acknowledgement Thanks a lot! The Champs-Élysées,, Paris (FR). 19