2. 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)

3. 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 70+ % 30- %

4. 3 Two DSM (“adaptive”) Steps 1.DON’T “HOG” (Each line uses minimum power) Adaptive Spectrum 2. 2.Cooperate Signal Alignment

5. 4 Outline Step One (Adaptive Spectra) –Margin/Rate management –Impulse/code management Step Two (Signal Alignment)

6. 5 DSM System Diagram Accepts data Processes data Provides recommendations Fiber DLCRT ADSL H or VDSL ADSL cable CO DSLAM RT + CLEC DSM CENTER ILEC Monitor Provision Maintain Monitor Provision Maintain

7. 6 DSM Data (to DSM Center) 1)ADSL1 Margins, powers, rates, bit table, code violations Current and max data rates 2)Web Pages / ADSL2 (WT87) Attenuation[n], Noise[n] 3)Loop “Make-Up” Report Lines at same service terminal (same and nearby binders) Common lengths (taper codes), bridged taps, total length I/CLEC DSM CENTER Monitor H or VDSL ADSL cable CO DSLAM (EMS)

8. 7 DSM Controls (from DSM Center) I/CLEC DSM CENTER Monitor H or VDSL ADSL cable CO DSLAM (EMS) 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 [3] [1] [2] Data rate [0] = current rate

9. 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)

10. 9 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 R long R short Spectral pair 1 Spectral pair 2 Current “static spectrum management”

11. 10 What is Politeness (Near/Far) ? (near transmitter “speaks softly” – transmits only power it needs) RT NEAR FAR CO Downstream Example Upstream Example LT NEAR FAR

12. 11 Telcordia DSM-ADSL Rate Regions [T1E1.4/2002-063] lines 1 & 3 (2 held at 1.6 Mbps) lines 1 & 2 (3 removed) – 063R1 Nominal 15 kft data rate without DSM –300 kbps AA AA Fiber, 10 kft 5 kft Copper, 15 kft A 15 kft Nominal 300 kbps

13. 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???

14. 13 Carrier A and DSM, CO/RT (ASSIA)

15. 14 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” NSR(f) S(f) NSR(f)S(f) “HOG” (margin = 30 dB)POLITE (margin << 30 dB)

16. 15 DSLAM to CPE 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) Modem 1 Modem 2 Modem 3 Modem 4 Modem 5

17. 16 Another Vendor Issue – “Virtual Noise” Telco sets a worst-case noise –Often wrong or not possible –Undue conservative (opposite of politeness)

18. 17 Use of VN Upstream VDSL near/far Same ILEC all lines Unbundled VN Politeness (IW)

19. 18 Outline Step One (Adaptive Spectra) –Margin/Rate management –Impulse/code management Step Two (Signal Alignment)

20. 19 A General Finding from FT work 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)

21. 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  s) DSM Center Center DSLAM SubscriberADSL Max impulse mode CRC Violations

22. 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

23. 22 Carrier C and DSM: Advanced INP

24. 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

25. 24 Cioffi DSL Line 2 8000’ loop (fiber-fed “remote terminal” RT) Provisioned at 1536 kbps, now running 6008 kbps with early DSM ADSL FEXT region 1500’ bridged-tap Noise AM radio Insertion loss Noise (also impulse not shown)

26. 25 Outline Step One (Adaptive Spectra) –Margin/Rate management –Impulse/code management Step Two (Signal Alignment)

27. 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

28. 27 STEP TWO – “Vectoring” (Signal Alignment) 20-100 Mbps (symmetric) Central Office ILEC LT/RT Switch router FIBER twisted pair DSLAMDSLAM DSM binder Note Fiber to RT or LT DSM

29. 28 Upstream – Multiple Access (per tone) One for each tone Lines synchronized and digitally duplexed 3 rd generation vectored DSLAM Works as if No NEXT or FEXT present W n =Q’ n + Y Z X 1,n G 1,n X 2,n G 2,n...... X L,n G L,n H n =Q n R nn (Loop) dec B n =R n Feedback or Packet detector One side

30. 29 Downstream Broadcast (per tone) Q’ n + Y Z 1,n D 1,n Z 2,n D 2,n...... Z L,n D L,n mod B n =R n Feedback or Packet precoder X n,i H n =R n Q nn () One for each tone Lines synchronized and digitally duplexed 3 rd generation DSLAM Works as if no FEXT present One side

31. 30 T-Systems (German -DT) Results VDSL with SHDSL (I)

32. 31 German results for VDSL with HDB3 (III)

33. 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) !

34. 33 Ultimate Result of Vectoring Distribution Area to 100 Mbps single line 1000M x 100 Mbps –Getting closer to the goal

35. 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)?

36. 35 GDSL? Pedestal drop –<300 meters –2 to 6 lines typical –Xtalk is self Last few 100 meters is $$$ for fiber GDSL

37. 36 Split-pairs/”phantoms” 76543210 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?

38. 37 Matrix Matched Load Resistor across all 7 possibilities

39. 38 Some Results (symmetric FDM)

40. 39 DSM DON’T “HOG” –Adaptive Spectrum –100M x 10M 2. 2.Cooperate Signal Alignment 1000M x 100M 100 M 3.GIGABIT DSL (GDSL) 1000M x 1000M G DSL