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Dynamic Spectrum Management ( 1000M x 1000M)

Dynamic Spectrum Management ( 1000M x 1000M). IEEE SCV Communications Society October 12, 2005 Speaker: J. Cioffi Stanford University (M. Mohseni, V. Pourahmad, M. Brady) cioffi@stanford.edu Special Thanks to: ASSIA Inc (Wonjong Rhee, I. Almandoz , G. Ginis, P. Silverman)

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Dynamic Spectrum Management ( 1000M x 1000M)

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  1. Dynamic Spectrum Management(1000M x 1000M) IEEE SCV Communications Society October 12, 2005 Speaker: J. Cioffi Stanford University (M. Mohseni, V. Pourahmad, M. Brady) cioffi@stanford.edu Special Thanks to: ASSIA Inc (Wonjong Rhee, I. Almandoz , G. Ginis, P. Silverman) SBC Network Systems Engineering (R. Savoor, S. Sposato) France Telecom (R&D) (H. Mariotte, M. Ouziff, F. Gauthier) British Telecom (K. Foster, J. Cook) Deutche Telekom T-Systems (S. Symalia, E. Berndt, J. Buhl) Alcatel Bell (DSM Research Group) Telcordia (K. Kerpez & D. Waring)

  2. Automated Maintenance (=DSM) • OPS = Majority of DSL effort • Reduce through electronic management of • Provisioning • Maintenance • Qualification • Capacity (rate/range) • Reduce “truck rolls” and improve overall ADSL performance • Permits higher speeds further 30- % 70+ %

  3. Two DSM (“adaptive”) Steps • DON’T “HOG” • (Each line uses minimum power) • Adaptive Spectrum • Cooperate • Signal Alignment

  4. Outline • Step One (Adaptive Spectra) • Margin/Rate management • Impulse/code management • Step Two (Signal Alignment)

  5. CO DLC RT RT+ ADSL Fiber ADSL H or VDSL DSLAM cable ADSL DSM System Diagram ILEC Monitor • Accepts data • Processes data • Provides recommendations Provision Maintain CLEC Monitor Provision Maintain DSM CENTER

  6. DSM Data(to DSM Center) I/CLEC CO • ADSL1 • Margins, powers, rates, bit table, code violations • Current and max data rates • Web Pages / ADSL2 (WT87) • Attenuation[n], Noise[n] • Loop “Make-Up” Report • Lines at same service terminal (same and nearby binders) • Common lengths (taper codes), bridged taps, total length Monitor H or VDSL DSLAM (EMS) cable ADSL DSM CENTER

  7. DSM Controls(from DSM Center) I/CLEC CO • Maxrate VECTOR • Maxrate[1] (present conditions) • Maxrate[2] = Difficult conditions • Maxrate[3] = Other DSLs doing DSM • Each may have different profile • Profile Recommendation • Rates/Margins • Code Choices Monitor H or VDSL DSLAM (EMS) ADSL cable [3] Data rate [1] DSM CENTER [3] [2] [0] = current rate

  8. DSL Subscriber (Initially 384 kbps) • 13.6 kft, currently at 384 kbps • Own power use (904 kbps) • Polite fiber-fed terminals (each held at 1.536 Mbps)

  9. Rlong Current “static spectrum management” Spectralpair 1 Spectral pair 2 Rshort DSM Multi-user Rate REGIONS • Plot of all possible rates of users • any point is possible • More than 2 users (vector of possible rate-tuples) • Fear of “hogs” forces the small area to be used • With worst-case FIXED models currently applied

  10. What is Politeness (Near/Far) ? (near transmitter “speaks softly” – transmits only power it needs) Downstream Example RT NEAR CO FAR Upstream Example LT NEAR FAR

  11. lines 1 & 3 (2 held at 1.6 Mbps) lines 1 & 2 (3 removed) – 063R1 Telcordia DSM-ADSL Rate Regions [T1E1.4/2002-063] 15 kft Fiber, 10 kft A A A Nominal 300 kbps 5 kft • Nominal 15 kft data rate without DSM • 300 kbps A A Copper, 15 kft

  12. Higher Speeds? Symmetric? (yes with DSM) • No coordination yet (but no hogging allowed) • No effect on existing ADSL if implemented with DSM • How did we do this???

  13. Carrier A and DSM, CO/RT (ASSIA)

  14. NSR(f) S(f) NSR(f) S(f) ADDNMR = Iterative Water-Fill • Minimize Power (at some max margin) • Diagram on right below • No coordination of modems • Service provider sets Rate & ADNMR • “Adaptive Spectrum” “HOG” (margin = 30 dB) POLITE (margin << 30 dB)

  15. Margins > 16 dB to 10 kft. Despite promise by vendors that 16 dB would not be exceeded CPE Problem? (no, CPE, DSLAM, and ITU standards all share in fault) DSLAM to CPE Modem 1 Modem 2 Modem 3 Modem 4 Modem 5

  16. Another Vendor Issue – “Virtual Noise” • Telco sets a worst-case noise • Often wrong or not possible • Undue conservative (opposite of politeness)

  17. Use of VN Upstream VDSL near/far Politeness (IW) VN Unbundled Same ILEC all lines

  18. Outline • Step One (Adaptive Spectra) • Margin/Rate management • Impulse/code management • Step Two (Signal Alignment)

  19. Use erasures and lower-rate RS codes When code/CRC violations found Use normal settings of (240,224) when no CRC violations (i.e., no impulses) A General Finding from FT work

  20. Steps to take? • Ask subscriber modem vendors for • Max-impulse protection option • Invoked by DSM Center when CRC or FEC violations noted • Almost in G.997.1 parameters (need > 500 ms) DSM Center Center DSLAM Subscriber ADSL CRC Violations Max impulse mode

  21. Live Subscriber – Bad Impulse • 10 kft 26-gauge • Intermittant noise, 0-400 kHz • Code Violations even with nominal “interleave” setting • 768 kbps • 28 dB DS margin, but CVs • 19 dB US margin, but CVs • After DSM : > 3 Mbps • Uses 48,32 FEC

  22. Carrier C and DSM: Advanced INP

  23. Cioffi DSL Line 1 • 17000’ loop • Provisioned at 192 kbps, now running 768 kbps with early DSM Noise (also impulse not shown) Insertion loss

  24. Cioffi DSL Line 2 • 8000’ loop (fiber-fed “remote terminal” RT) • Provisioned at 1536 kbps, now running 6008 kbps with early DSM Insertion loss 1500’ bridged-tap AM radio ADSL FEXT region Noise (also impulse not shown) Noise

  25. Outline • Step One (Adaptive Spectra) • Margin/Rate management • Impulse/code management • Step Two (Signal Alignment)

  26. Bonding ≠ Vectoring • Bonding • Use N lines to get N x the data rate • Possible to vector also, but bonding does not force use of vectoring • Mux and inverse Mux • Vectoring • Cogenerate at PHY level signals and/or • Coreceive at PHY level signals • Can do one-sided without bonding • Can do one/two-sided with vectoring

  27. STEP TWO – “Vectoring”(Signal Alignment) • Note Fiber to RT or LT Central Office b i n d e r ILEC LT/RT FIBER D S L A M Switch router 20-100 Mbps (symmetric) DSM twistedpair DSM

  28. Upstream – Multiple Access (per tone) One side G1,n X1,n Feedback or Packet detector • One for each tone • Lines synchronized and digitally duplexed • 3rd generation vectored DSLAM • Works as if No NEXT or FEXT present Z Y Hn=QnRnn (Loop) G2,n X2,n Wn=Q’n + dec . . . GL,n XL,n Bn=Rn

  29. Downstream Broadcast (per tone) One side • One for each tone • Lines synchronized and digitally duplexed • 3rd generation DSLAM • Works as if no FEXT present Feedback or Packet precoder D1,n Z1,n Hn=RnQnn () D2,n Z2,n + Xn,i Q’n mod . . . Y DL,n ZL,n Bn=Rn

  30. T-Systems (German -DT) ResultsVDSL with SHDSL (I)

  31. German results for VDSL with HDB3 (III)

  32. Symmetric Rates – AS (green) vs SIA (blue) • Increases data rates at all lengths with Vectored DSLAM • Power can be lowered – possible to do 10 dBm or less • 100 Mbps (single line, no bonding) at 1500 ft symmetric, 2500 ft asymmetric • Cioffi’s 17 kft loop to 2.5 Mbps (256 kbps up) !

  33. Ultimate Result of Vectoring • Distribution Area to 100 Mbps single line • 1000M x 100 Mbps • Getting closer to the goal

  34. The Wireless Power Co ? • Hmmm …….. • Lots of antenna’s needed for 100 Mbps (both sides) • Lots of power for 100 meters or more also • Perhaps high-speed wireless LAN stays at end of DSL (like today)?

  35. GDSL? • Pedestal drop • <300 meters • 2 to 6 lines typical • Xtalk is self • Last few 100 meters is $$$ for fiber GDSL

  36. Split-pairs/”phantoms” 7 6 5 4 3 2 1 0 There are actually 7 independent channels in those 4 loops all 7 have high capacity Well over 1000 Mbps at 300 meters (category 3) Vector 7x7 channel Pedestal drop DSL – how fast?

  37. Matrix Matched Load • Resistor across all 7 possibilities

  38. Some Results (symmetric FDM)

  39. DON’T “HOG” Adaptive Spectrum 100M x 10M DSM • Cooperate • Signal Alignment • 1000M x 100M 100 M 100 M 3. GIGABIT DSL (GDSL) • 1000M x 1000M G DSL

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