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Dynamic Spectrum Management

Dynamic Spectrum Management. July 2002. John M. Cioffi Prof. EE, Stanford U. Cioffi@stanford.edu And all the work by students: Taek Chung, George Ginis, Jeannie Fang, Jungwon Lee, Dimitris Toumpakaris, & Wei Yu. Copper has more bw than fiber?. fiber.

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Dynamic Spectrum Management

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  1. Dynamic Spectrum Management July 2002 John M. Cioffi Prof. EE, Stanford U. Cioffi@stanford.edu And all the work by students: Taek Chung, George Ginis, Jeannie Fang, Jungwon Lee, Dimitris Toumpakaris, & Wei Yu

  2. Copper has more bw than fiber? fiber • DSL will deliver 100 Mbps symmetric to all • 50 line bundle (500 meters of cat 3 tp) • 50 lines (100 Mbps/line) = 5 Gbps • FTTH shares 622 Mbps among 50 or more homes in PON architecture (even “future” systems are 2.5 Gbps) • So, where is DSL today? • Where is DSL going? Cable of copper pair

  3. A/VDSL Closer DSLAM ONU/RT router Enet. 1000BT VoDSL Interface IEEE 802.X Enet Fiber (from CO) wireless (802.11,15) or other distribution possible within CPE, 11, 55, 100-500 Mbps 802.11 DSL 200X- (V/M/ADSL) 10/100 Mbps • Data , Voice , Video …

  4. DSM HDSL / ADSL … 2000 2001 2002 2003 DSM=Dynamic Spectrum Management “EFM” 10MDSL • Standard in progress – USA (ANSI / T1E1.4) • Dynamic – loops, xtalk, rates very • Not limited by worst-case static situations • Extension to existing Spec Management • T1.417-2002 • Improve considerably reliability and performance • Cannot have spectrum compatibility at higher speeds without DSM • Crosstalk effect is too strong for static regulation • THIS IS A CRUCIAL turning point for DSL • Goals: 100 Mbps symmetric everywhere • & Improve the range of every rate < 100 Mbps SM (static) VDSL 100MDSL ADSL+ VDSL-2

  5. Outline • Crosstalk and Management • Autonomous (de-regulated) DSL • Bonded/Vectored DSL

  6. FEXT NEXT DSL’s Challenge: Crosstalk user Phone Co=Base (DSLAM) • Same service provider • Different service provider • Management? • Spectrum – fixed or static • Ok, but performance and reliability severely compromised • Symmetric versus asymmetric user

  7. Some Crosstalk • Xtalk noise increases with frequency FEXT – British Telecom (gain) NEXT - Bellcore (attenuation)

  8. CPE DSL CO DSLs CPE DSL CPE DSL CO DSL CPE DSL LT DSL Loop Topology • Many other configurations • symmetric/asymmetric mixtures • Data rate mixtures • Shorter lines • Bonding of lines

  9. TWISTED-PAIR Atten Bits/chan Bits/chan Frequency Frequency Frequency TWISTED-PAIR with TAP, AM/RF, and XTALK Atten AM Bits/chan Bits/chan xtalk Frequency Frequency ADSL DMT Loading Basics(adapts to each line) Frequency 800 Million phone lines and growing fast! Bellcore tests, 1993 (ANSI Standard) GTE tests, 1996 ; NSTL, 1996

  10. bi n d e r ILEC DSLAM 1 Central Office 1-20 Mbps (asymmetric/ symmetric) Present DSL 2002: autonomous (no coordination) SMC for provisioning, Fault isolation Network ILEC DSLAM 2 SMC1 CLEC DSLAM SMC2 Evolving DSL 2002+: Bonding Vectoring Common DSLAM (LT or RT) Central Office b i n d e r Content 1 Content 2 Fiber Or multi-channel DSL ILEC LT D S L A M 20-100 Mbps (symmetric) Switch router Network SMC twistedpair Evolution of Crosstalk / management time

  11. Outline • Crosstalk and Management • Autonomous (de-regulated) DSL • Bonded/Vectored DSL bi n d e r ILEC DSLAM 1 Central Office 1-20 Mbps (asymmetric/ symmetric) Present DSL 2002: autonomous (no coordination) SMC for provisioning, Fault isolation Network ILEC DSLAM 2 SMC1 CLEC DSLAM SMC2

  12. DSL 1 Shared binder H(f) DSL 1 DSL 2 DSL 2 DSL K DSL K Model: Autonomous Case • Crosstalk between users is “matrix channel” • “Interference channel” in information theory • Can users be compatible without large loss? (SSM – no, DSM - yes) . . .

  13. Spectralpair 1 Spectral pair 2 DSM Multi-user Rate REGIONS Rlong • Plot of all possible rates of users • ADSL & some VDSL use DSM – any point is possible • More than 2 users (vector of possible rate-tuples) • Region’s size (volume) can vary with: • each binder • transmission methods (i.e., DMT has much larger regions) Rshort

  14. ANSI DSM ADSL “Blueprint” Example(T1E1.4/2001- 273, 278) ADSL CO 10 + X kft ADSL rcvr • CLASSIC field problem with ADSL present-day deployments • Long-line often does not work and field personal have to be dispatched • Improve the performance of line 1 AUTONOMOUSLY (no coordination) using DSM-mode in ADSL modems • Eliminate problem automatically • Greatly extend ADSL range Line 1 10 kft ADSL RT 5 kft ADSL rcvr Line 2 fiber CO Same binder FEXT

  15. DSM ADSL basic spectrum result Downstream Spectra (2 lines) • Short line yields to long • No “DSL hogging” • Enormous improvement on long line • At expense of reduced rate on short line • Do so autonomously Initial Short-line spectra, Long-line turns on Long Line spectra Intermediate Short-line spectra, Intermediate Short-line spectra, Short-line spectra f

  16. Verizon Experimental Loop Configuration(T1E1.4/2002-069 – “Bell Atlantic” Test Lab, Maryland) Simulation of CO-ADSL fed through RT binder with RT-ADSL 14 kft 6 kft Cable Vault Cable Vault Mainframe Mainframe Pair 16 of 6 kft, 26 gauge 25-pair binder (Simulates RT portion of loop) Pair 1 of 14 kft, 24 gauge 25-pair binder Pair 17 of 6 kft, 26 gauge 25-pair binder (Simulates RT-ADSL loop) Remote Side Remote Side CO side Remote Side CO side ATU-R ATU-R ATU-C ATU-C CO ADSL RT ADSL Verizon Broadband Integration Lab

  17. Crosstalk into pair 17 Pair  Noise (dB)        Pair  Noise (dB) 1     -82.5                   13    -84.4 2     -78.1                   14    -80.7 3     -74.9                   15    -77.7 4     -82.3                 16    -63.2 5     -83.0                   18    -67.7 6     -84.2                   19    -67.5 7     -78.0                   20    -76.9 8     -81.0                   21    -80.8 9     -75.3                   22    -78.7 10    -73.3                   23    -78.0 11    -79.6                   24    -73.4 12    -82.7                   25    -80.7 • Used worst-case FEXT coupling pairs for experiment

  18. DSM-ADSL Rate Region (Verizon loops) • Rate-Adaptive produces (9,.1) • Mode used by Verizon nominally in lab • Instead, DSM-mode provides (Short, Long) = • (2, 1.8), (4, 1.4), (6, .9) , and (8, .6)

  19. ADSL CO 15 kft ADSL rcvr Line 1 10 kft (fiber) ADSL RT 5 kft ADSL rcvr Line 2 15 kft 10 kft (fiber) ADSL RT ADSL rcvr Line 3 CO Same binder FEXT Telcordia (Bellcore) Results “Blueprint” Test(T1E1.4/2002-063) ADSL CO ADSL rcvr • Improve the performance of lines 1 and 3 (which is bad under RA operation) • Line 1 only operates at 300 kbps in “normal” mode ADSL rcvr ADSL RT ADSL RT ADSL rcvr

  20. lines 1 & 2 (3 removed) – 063R1 Telcordia DSM-ADSL Rate Regionst1e1.4/2002-063 • No coordination (line 2 held at 6 dB margin, 1.6 Mbps • 4x improvement on Line 1 (was at 300 kbps if line 2 does RA or margin-max training) – like “Verizon” expt. • 4x because 15kft, not 20 kft like Verizon lines 1 & 3 (2 held at 1.6 Mbps)

  21. DSM Algorithm (Iterative-Water-filling) • Water-filling is known optimum on single-user channel • Use DMT, and MINIMIZE POWER for given rate/margin • Best autonomous solution to “interference problem” in binder • The more lines that do DSM, the better they all work • NEVER any worse than existing fixed/static Spectrum Management • AUTONOMOUS – no coorination necessary, procedure assures overall best mutual spectra (least harmful xtalk) of all DSLS in distributed fashion NSR(f) S(f)

  22. Dynamic Spectrum Management BDSL to D: 100 Mbps U: 100 Mbps 1-4 lines/LT 0-2 km AMDSL to D: 25 Mbps U: 10 Mbps 1-2 lines CO/LT 0-4 km … 2002 2003 2004 3-steps to Broadband DSL • DSM • ADSL -Software option in current ADSL modems • ADSL+ & 10M-DSL (DMT only) – iterative wf • 100M-DSL (DMT only) ADSL to D: 7 Mbps U: .3 Mbps 1 line 0-6 km

  23. 10MDSL (EFM) Range/Rate Goals [1]

  24. 25 10MDSLs in same binder (same length) • No coordination • 10 Mbps single-line range is 2.5x SSM result (SHDSL) • 10 Mbps >1.5 km on 2 lines Verified By Voyan Verified By Telcordia

  25. Example PSD for 4000’ • Overlap (EC) to 800 kHz • Each has 3 basic bands

  26. MDSL with ADSL present • Range of ADSL and of MDSL unaffected if DSM is used • Not true for Static SM (or SHDSL)

  27. ADSL at CO, MDSL at RT • Cabinet is 10 kft from CO – last 2 to 6 kft in same binder • ADSL at CO “swamped” by 64 PAM • ADSL at CO largely unaffected by IW Copper, 4 kft Fiber, 10 kft M M A A Copper, L kft 12, 14, 16

  28. VDSL vs MDSL rate regions • Fixed is 998 on V and 1 MHz on M • Still exceeds all targets of M and V

  29. Table 2 – Augmentation of Table 1 with IW results Aggregate bit rate (sym payload) # of twisted pairs Average bit rate per pair Objective loop length Desired loop length DSM Result 10 Mb/s 1 10 Mb/s 2.5 kft >3.5 kft 5 kft 10 Mb/s 2 5 Mb/s 4 kft >5 kft 8 kft 10 Mb/s 3 3.33 Mb/s 5.5 kft >6.5 kft 9 kft 10 Mb/s 4 2.5 Mb/s 7 kft >8 kft 10 kft 10 Mb/s 5 2 Mb/s 8 kft >9 kft achieved 4 Mb/s 4 1 Mb/s 12 kft >12 kft achieved 2 Mb/s 4 512 kb/s 15 kft >15 kft achieved Table Revisted (extra column) • Allows mixture of ADSL with MDSL, and VDSL with MDSL • Rate regions do reduce in size for VDSL • But all VDSL and MDSL goals still exceeded

  30. 998 Plan with Iter-water (VDSL) • Rates exceed VDSL objectives • Note spectra converges to 998 when 998 is present (4000’ MDSL)

  31. Basic Principles - Summary • No DSL modem should use more transmit power than it needs • No DSL modem should use more bandwidth than it needs • Can be solved adaptively and autonomously • Stop proliferating DSL standards and incompatible spectrum management

  32. Basic Solution • Use/Extend ADSL DMT Frequency Grid • Already on 24 million lines (> 95% of market) • ADSL+ = 512 tones down / 128 up • 10MDSL= 1024 tones down/1024 up • VDSL = 2048 up/down • 100MDSL 4096 up/down

  33. Outline • Crosstalk and Management • Autonomous (de-regulated) DSL • Bonded/Vectored DSL Evolving DSL 2002+: Bonding Vectoring Common DSLAM (LT or RT) Central Office b i n d e r Content 1 Content 2 Fiber Or multi-channel DSL ILEC LT D S L A M 20-100 Mbps (symmetric) Switch router Network SMC time twistedpair

  34. Coordinated 2-sided Signals (vector bonding) • Full Vectoring Problem • Highest data rates Shared channel Bonded lines Bonded lines Controller Controller

  35. User 1 LT DSLAM User 2 . . . Controller User K DSM Level 2: Coordinated 1-sided Signals Shared channel • “broadcast” and “multiple-access” probs in IT • One-sided vectoring, FDM of up/down • Bonding (vector broadcast and vector MA problems in IT)

  36. 998 with/without Vectoring • Enormous gain, especially upstream at shorter lengths where FEXT is large

  37. Full Vectoring (sum up/down) 100 Mbps range – 500 meters , single line • 1 km on 2 lines • >1.5 km on 4 lines • Even when partially vectored, 100 Mbps on 2 lines at 500 m, 1 km on 4 lines

  38. Broadband DSL • Enables video, data, voice services and packaging

  39. 3 steps Dynamic Spectrum Management • ANSI 2001-200R5, 2002-018, 057, 059, 127, 129 • http://isl.stanford.edu/~cioffi/dsm/index.html • Looking to collaborate with service/content providers, equipment/semi companies BDSL to D: 100 Mbps U: 100 Mbps 1-4 lines/LT 0-2 km ADSL to D: 7 Mbps U: .3 Mbps 1 line 0-6 km AMDSL to D: 25 Mbps U: 10 Mbps 1-2 lines CO/LT 0-4 km … 2002 2003 2004

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