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VDSL 技術介紹

VDSL 技術介紹. 暨南大學 電機系 魏學文 Will@ncnu.edu.tw. MULTIMEDTIA TO THE HOME. References. Part 1: Functional Requirements and Common Specification Part 2: Technical Specification for Single-Carrier Modulation (SCM) Transceivers

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VDSL 技術介紹

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  1. VDSL技術介紹 暨南大學 電機系 魏學文 Will@ncnu.edu.tw MULTIMEDTIA TO THE HOME

  2. References • Part 1: Functional Requirements and Common Specification • Part 2: Technical Specification for Single-Carrier Modulation (SCM) Transceivers • Part 3: Technical Specification for Multi-Carrier Modulation (MCM) Transceivers

  3. VDSL Transmission Schemes • FTTEx • Fiber to the exchange • FTTCab • Fiber to the cabinet Fiber to the node & Fiber to the building

  4. VDSL Access Technology Source: Orkit Co.

  5. FTTB + VDSL Source: Orkit Co. Building Fiber

  6. FSAN reference architecture

  7. VDSL Reference Model

  8. Reference Model

  9. VDSL Protocol Reference Model

  10. VDSL Payload Bit Rate

  11. Service Distance • S for short range (< 1 kft); • M for medium range (1kft-3kft); • L for long range (3kft-4.5kft).

  12. Central Office Deployment Scenario Cabinet Deployment Scenario VDSL maximum transmit power Downstream (dBm) Upstream (dBm) Downstream (dBm) Upstream (dBm) 14.5 14.5 11.5 14.5 (?)

  13. Frequency (kHz) PSD (dBm/Hz) In-Band PSD (Down stream- Co case) Mask 1 Mask 2 0-4 -101 -101 25 - 40 - 40 1104 - 40 - 40 1622 -60 -50 3750 -60 -53.5 3750 - 5200 Out-of-band PSD 5200 -60 -55 8500 -60 -55 8500 - 12000 Out-of-band PSD

  14. TX PWR= 14.5 dBm

  15. In-Band PSD (Down stream- Cab case)

  16. Frequency (kHz) PSD (dBm/Hz) IN-Band PSD (Upstream-CO) Mask 1 Mask 2 0 – 4 - 101 - 101 25 - 38 - 38 138 - 38 - 38 338 - 3750 Out-of-band PSD 3750 -60 -53 5200 -60 -53 5200 - 8500 Out-of-band PSD 8500 -60 -54 12000 -60 -54

  17. Frequency MHz Maximum PSD (PSDmax), dBm/Hz Maximum Power in a 1MHz sliding window Pmax, dBm Out of Band PSD < 0.12 -120 - 0.12 - 0.225 -110 - 0.225-4.0 -100 - 4.0 -5.0 -100 -50 5.0 - 30.0 -100 -52 >=30.0 -120 - Transition frequency -80 - D fT <= 175 kHz

  18. Separating Frequencies (MHz) f1 f2 f3 f4 f5 VDSL Band Allocation 0.138 3.75 5.2 8.5 12 VDSL transceiver shall use Frequency Division Duplexing (FDD) to separate upstream and downstream transmission.

  19. PMD Functional Model for SCM Systems

  20. PMD Functional Model for MCM Systems

  21. QAM/CAP VDSL 技術

  22. Single Carrier Modulation (SCM)- QAM/CAP

  23. Modulation • CAP/QAM • Constellation point: 4, 8(optimum), 16, 32, 64, 128, 256 • Differential encoding • Spectral shaping filter • Carrier spectral shaping • FEC: RS code over GF(28), codeword= 255, t = 0, 1, 2, 8

  24. 8-point Constellation and Bit Mapping

  25. Differential Bit Encoding

  26. Symbol Rates and Carrier Frequencies All available symbol rates (SR) in both downstream and upstream directions shall be multiples of the Basic Symbol Rate (BSR): SR = BSR  s where s is an integer, BSR = 67.5 kbaud. The carrier signal frequencies for transmitters using BSS should be a rational multiple of BSR/2: fc = BSR/2 k, [MHz], where k is an integer. The resulting shifting granularity is equal to 33.75 kHz.

  27. Profile code Carrier Symbol Rate RS (Mbaud) Constell. C Data RateDR (Mb/s) Total RateTR (Mb/s) Maximum Payload Rate (Mb/s) Asymmetric Profiles: Bit Rates AL-32OA 1D 2.160 (32x67.5) 32 10.8 DS 10.8 9.653 1U 0.945 (14x67.5) 4 1.89 US 1.89 1.689 AL-12ON 1D 2.700 (40x67.5) 64 16.2 DS 16.2 14.48 1U 0.945 (14x67.5) 8 2.835 US 2.835 2.534 1D 2.160 (32x67.5) 64 12.96 DS 17.28 15.445 AM-21OA 2D 2.160 (32x67.5) 4 4.32 1U 0.945 (14x67.5) 32 4.725 US 4.725 4.223 1D 2.700 (40x67.5) 256 21.6 DS 25.920 23.168 AM-01ON 2D 2.160 (32x67.5) 4 4.32 1U 0.945 (14x67.5) 32 4.725 US 4.725 4.223 1D 2.160 (32x67.5) 256 17.28 DS 25.920 23.168 AM-01OA 2D 2.160 (32x67.5) 16 8.64 1U 0.945 (14x67.5) 32 4.725 US 4.725 4.223

  28. Profile code Carrier Carrier frequency(MHz) Lowest frequency(MHz) Highest frequency(MHz) Maximum PSD (dBm/Hz) Asymmetric Profiles: Band Allocation AL-32OA 1D 2.2275 (66x33.75) 0.93 3.52 -60 1U 4.5225 (134x33.75) 3.96 5.09 AM-12ON 1D 1.8225 (54x33.75) 0.2 3.44 1U 4.5225 (134x33.75) 3.96 5.09 1D 2.2275 (66x33.75) 0.93 3.52 AM-21OA 2D 6.885 (204x33.75) 5.59 8.18 1U 4.5225 (134x33.75) 3.96 5.09 1D 1.8225 (54x33.75) 0.2 3.44 AM-01ON 2D 6.885 (204x33.75) 5.59 8.18 1U 4.5225 (134x33.75) 3.96 5.09 1D 2.2275 (66x33.75) 0.93 3.52 AM-01OA 2D 6.885 (204x33.75) 5.59 8.18 1U 4.5225 (134x33.75) 3.96 5.09

  29. Profile code Carrier Symbol Rate RS (Mbaud) Constell. C Data RateDR (Mb/s) Total RateTR (Mb/s) Maximum Payload Rate (Mb/s) Symmetric Profiles: Bit Rates SL-32OA 1D 1.620 (24x67.5) 8 4.86 DS 4.86 4.334 1U 0.945 (14x67.5) 32 4.725 US 4.725 4.223 1D 1.890 (28x67.5) 16 7.56 DS 7.56 6.757 SM-33OA 1U 0.945 (14x67.5) 32 4.725 US 7.56 6.757 2U 1.4175 (21x67.5) 4 2.835 1D 2.160 (32x67.5) 128 15.12 DS 15.12 13.515 SS-03OA 1U 0.945 (14x67.5) 64 5.67 US 14.31 12.791 2U 2.160 (32x67.5) 16 8.64

  30. Profile code Carrier Carrier frequency(MHz) Lowest frequency(MHz) Highest frequency (MHz) Maximum PSD (dBm/Hz) Symmetric Profiles: Band Allocation 1D 1.890 (56x33.75) 0.92 2.87 -60 SL-32OA 1U 4.5225 (134x33.75) 3.95 5.09 2U 10.125 (300x33.75) 9.27 10.98 1D 2.0925 (62x33.75) 0.96 3.23 SM-33OA 1U 4.5225 (134x33.75) 3.95 5.09 2U 10.125 (300x33.75) 9.27 10.98 1D 2.2275 (66x33.75) 0.93 3.52 SS-03OA 1U 4.5225 (134x33.75) 3.96 5.09 2U 10.530 (312x33.75) 9.23 11.83

  31. Spectral Shaping Filters square-root raised-cosine (  = 0.20 )

  32. Normalized frequency x Lower Bound dB Upper Bound dB Carrier Spectrum Shaping -1.5 < - 40 - 1.4 < - 40 - 1.3 < - 30 - 1.2 < - 24 -1.1 -20.0 -8.0 -1.0 -5.0 -3.0 -0.9 -2.7 -0.7 -0.8 -2.0 0 0 -2.0 0 0.8 -2.0 0 0.9 -2.7 -0.7 1.0 -5.0 -3.0 1.1 -20.0 -8.0 1.2 < - 24 1.3 < - 30 1.4 < - 40 1.5 < - 40

  33. VDSL chip: QAM structure

  34. DMT VDSL 技術

  35. Modulation • DMT • Sub-carriers: 2n+8; 256-4096 • Carrier spacing= 4.3125KHz (8.625kHz?) • Using both CP and CF; 40-640 • Using block shaping: shaping length B <= 162n; • Cyclic extension, CE= CP+CF – B = 402n • Constellation point: 4, 8(PTT), 16, 32, …, 2k; 8<= k <= 15 • Pilot tones are optional • Synchronous mode is optional • FEC: RS code over GF(28), codeword <= 255, t =0, 12, …, 8; (240,224), (144, 128) are basic modes.

  36. Cyclic extension and block shaping

  37. Cyclic extension expressed in samples maximum of sub-carriers Nsc x 2n CP and Sub-carriers 40 256 80 512 160 1024 320 2048 640 4096

  38. Symbol Rate

  39. Timing Advance (TA) • The VTU-R shall be capable of implementing a timing offset called timing advance (TA) in the transmission of DMT symbols. • The TA forces the VTU-O/VTU-R pair to start transmissions of frames in opposite directions simultaneously (i.e. the frames in downstream and upstream transmission direction start at the same (absolute) time). • The timing advance shall be equal to the propagation delay from the VTU-O to the VTU-R. • It shall be calculated by the VTU-R during initialization.

  40. Synchronous mode (optional) • In synchronous mode, all VTU-O transceivers in the same cable binder shall transmit with respect to a common symbol clock, and thus start the transmission of DMT symbols at the same time.

  41. Filtered Multi-tone ?

  42. Frequency response of prototype filter

  43. TLV3220VD30 (TI)

  44. TLV3220VD30 (TI)

  45. RFI Cancellation

  46. 頻帶重疊所造成的RFI Copy from卲玄綺 • VDSL與某些Radio Transmission產生Electromagnetic Compatibility(EMC) 的問題 : - 商業調幅(AM)廣播服務: 長波(LW)，中波(MW)頻段，535 ~ 1605 kHz - 業餘無線電(Amateur Radio): 散佈在離散的頻段上. - 一些目前未列入考慮的訊號源，例如短波(SW)發射機. Source: Orkit Co.

  47. 雜訊侵出(Egress)問題 Copy from卲玄綺 • 曝露於室外的雙絞線會如同天線般輻射能量的原因 - 電話線路的平衡度(balance)隨著頻率增加而遞減 一般電話線的平衡度在60 dB以上(語音頻率)，隨頻率增加會降至10~30 dB - VDSL訊號的頻率增加(波長變短)造成纜線的天線輻射效率增加 Aerial Dropwire VDSL產生電磁波干擾(EMI)

  48. 雜訊侵入(Ingress)問題 Copy from卲玄綺 • 曝露於室外的雙絞線會如同天線般接收干擾 - 纜線會接收來自於外部其他訊號源的射頻訊號造成干擾 - 在近距離內的AM發射站台會對VDSL產生嚴重的威脅 Aerial Dropwire

  49. VDSL PSD MASK SOURCE: IEEE Commun. Mag.

  50. 調幅廣播射頻雜訊特性與模型建構 Copy from卲玄綺 • 調幅廣播訊號以30 % AM DSB-TC (Double Sideband with Transmission Carrier)來產生: 訊號源m(t) 頻寬 = 5 kHz 頻寬 = 10 kHz

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