VDSL????

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VDSL????
???? ??? ??? Will_at_ncnu.edu.tw
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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

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VDSL Transmission Schemes

• FTTEx
• Fiber to the exchange
• FTTCab
• Fiber to the cabinet
• Fiber to the node Fiber to the building

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VDSL Access Technology
Source Orkit Co.
5
FTTB VDSL
Source Orkit Co.
Building
Fiber
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FSAN reference architecture
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VDSL Reference Model
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Reference Model
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VDSL Protocol Reference Model
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VDSL Payload Bit Rate
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Service Distance

• S for short range (lt 1 kft)
• M for medium range (1kft-3kft)
• L for long range (3kft-4.5kft).

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VDSL maximum transmit power
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In-Band PSD (Down stream- Co case)
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TX PWR 14.5 dBm
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In-Band PSD (Down stream- Cab case)
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IN-Band PSD (Upstream-CO)
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Out of Band PSD
D fT lt 175 kHz
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VDSL Band Allocation
VDSL transceiver shall use Frequency Division
Duplexing (FDD) to separate upstream and
downstream transmission.
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PMD Functional Model for SCM Systems
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PMD Functional Model for MCM Systems
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QAM/CAP VDSL ??
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Single Carrier Modulation (SCM)- QAM/CAP
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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

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8-point Constellation and Bit Mapping
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Differential Bit Encoding

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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.

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Asymmetric Profiles Bit Rates
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Asymmetric Profiles Band Allocation
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Symmetric Profiles Bit Rates
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Symmetric Profiles Band Allocation
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Spectral Shaping Filters
square-root raised-cosine ( ? 0.20 )
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Carrier Spectrum Shaping
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VDSL chip QAM structure
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DMT VDSL ??
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Modulation

• DMT
• Sub-carriers 2n8 256-4096
• Carrier spacing 4.3125KHz (8.625kHz?)
• Using both CP and CF 40-640
• Using block shaping shaping length B lt 16?2n
• Cyclic extension, CE CPCF B 40?2n
• Constellation point 4, 8(PTT), 16, 32, , 2k
  8lt k lt 15
• Pilot tones are optional
• Synchronous mode is optional
• FEC RS code over GF(28), codeword lt 255, t 0,
  12, , 8 (240,224), (144, 128) are basic modes.

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Cyclic extension and block shaping
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CP and Sub-carriers
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Symbol Rate
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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.

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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.

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Filtered Multi-tone ?
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Frequency response of prototype filter
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TLV3220VD30 (TI)
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TLV3220VD30 (TI)
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RFI Cancellation
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????????RFI
Copy from???

• VDSL???Radio Transmission??Electromagnetic
  Compatibility(EMC)
• ???
• - ????(AM)???? ??(LW),??(MW)??,535 1605
  kHz
• - ?????(Amateur Radio) ?????????.
• - ?????????????,????(SW)???.

Source Orkit Co.
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????(Egress)??
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• ??????????????????????
• - ????????(balance)?????????
• ? ??????????60 dB??(????),????????1030
  dB
• - VDSL???????(????)?????????????

Aerial Dropwire
VDSL???????(EMI)
48
????(Ingress)??
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• ???????????????????
• - ????????????????????????
• - ??????AM??????VDSL???????

Aerial Dropwire
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VDSL PSD MASK
SOURCE IEEE Commun. Mag.
50
???????????????
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• ???????30 AM DSB-TC (Double Sideband with
  Transmission
• Carrier)???

??? m(t)
?? 10 kHz
?? 5 kHz
51
???????????????
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AM????? ?? 660 kHz, ??-30dBm
ANSI T1E1.4 AM RFI Threat Model 1?????10?????,
???AM???
52
????????????????
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• ?????????

ANSI ???????????
ETSI ???????????
53
????????????????
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• ????????AM-SSB(Single Sideband)???

54
????????????????
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• ????ITU-T Rec.G.227???????

IFFT
??????
??ITU-T Rec.G.227???????
55
????????????????
Copy from???
Amateur Radio????? ?? 1.81 MHz, ?? -5 dBm
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RFI CANCELLER
SOURCE IEEE Commun. Mag.