Published on November 28, 2007
Introducing the Next Generation ADSL Standard ITU-T Rec. G.992.3/4 (ADSL2): Introducing the Next Generation ADSL Standard ITU-T Rec. G.992.3/4 (ADSL2) Frank Van der Putten Q4/15 Associate Rapporteur for ADSL2 and ADSL+ Overview: Overview What we have today: G.992.1&2 Top 10 improvements with G.992.3 The lite version: G.992.4 The next steps: ADSL+ and SELT What G.992.1/G.992.2 offer today: What G.992.1/G.992.2 offer today June 1999: The ITU-T SG15 approves 6 ADSL recommendations G.992.1 ADSL Transceivers G.992.2 Splitterless ADSL Transceivers G.994.1 Handshake Procedures for DSL transceivers G.995.1 Overview of DSL Recommendations G.996.1 Test Procedures for DSL Transceivers G.997.1 Physical Layer management for DSL Transceivers G.992.1/2 has ADSL over ...: G.992.1/2 has ADSL over ... G.992.1 ANNEX A FULL RATE ADSL over POTS Overlapped Spectrum PSD Masks Non-overlapped Spectrum PSD Masks G.992.1 ANNEX B FULL RATE ADSL over ISDN Overlapped Spectrum PSD Masks only G.992.1 ANNEX C FULL RATE ADSL in TCM-ISDN binder PSD Masks as for G.992.1 ANNEX A G.992.2 ANNEX A LITE ADSL over POTS Overlapped Spectrum PSD Masks Non-overlapped Spectrum PSD Masks G.992.2 ANNEX C LITE ADSL in TCM-ISDN binder PSD Masks as for G.992.2 ANNEX A What direction to take next ?: What direction to take next ? Real world: Bridged taps, Crosstalk & Narrowband Interferers Ease of CPE installation Enabling applications: voice, games and video The green line: Power savings Adaptation to time varying line conditions Enabling implementation technologies ADSL Anywhere: RU deployment Monitoring and trouble resolution tools All Digital Mode Egress Friendliness Multi-vendor Interoperability After 3 years of field experience … ITU-T takes the next step : ITU-T takes the next step The ITU-T SG15 has achieved consent on the second generation ADSL Recommendations, 10 May 2002 Consent = Last Call for comments (starts end June) G.dmt.bis = G.992.3 = ADSL2 G.lite.bis = G.992.4 = Splitterless ADSL2 Approval expected Q3/2002 Top 10 improvements of ADSL2 (G.992.3) (1): Top 10 improvements of ADSL2 (G.992.3) (1) Performance: raising the bar Min 8 Mbit/s down, scales to max 15 Mbit/s Min 800 kbit/s up, scales to max 1.5 Mbit/s Trellis coding, 1-bit constellations, data on pilot DSL Forum TR-048 for North-America (annex A) ETSI TS 101 388 V1.3.1 for Europe (annex A&B) Loop Diagnostics Tools Special initialization to diagnose the loop Measure Loop Attenuation, Quiet Line Noise and Signal-to-Noise Ratio over ADSL band Double ended line testing for trouble resolution Top 10 improvements of ADSL2 (G.992.3) (2) : Top 10 improvements of ADSL2 (G.992.3) (2) Improved initialization Receiver allocated pilot (avoid bridged taps & RFI) Enabling RFI cancellation techniques Better equalization with spectrum shaped init signals Receiver chooses configuration (no longer 4 options) Receiver determined duriation of init signals Fast start-up: 3 seconds As error recovery in Showtime From stand-by/sleep state Uses data rate fine tuning in Showtime (SRA) Top 10 improvements of ADSL2 (G.992.3) (3) : Top 10 improvements of ADSL2 (G.992.3) (3) On-Line Reconfiguration (OLR) Track application and BER requirements Bitswap (improved protocol robustness) Dynamic Rate Repartitioning (e.g., for CVoDSL) Seamless Rate Adaptation (change data rate) Power Management (PM) Statistical powersave based on user activity Low data rate state (service keep-alive data only) Low delay return to full rate Showtime (0.5 msec) Stand-by/sleep state (user asleep, modem asleep) Top 10 improvements of ADSL2 (G.992.3) (4) : Top 10 improvements of ADSL2 (G.992.3) (4) Framing Up to 4 frame bearers and up to 4 latency paths Delay and BER configurable per frame bearer Scales to support high data rates (no S=1/2 “trick”) Scales for better coding and long loop performance Overhead rate of 4 to 64 kbit/s for OAM/OLR/PM All Digital Mode (no underlying service) Extending ADSL band to DC 32 (Annex I) or 64 (Annex J) upstream tones Additional 256 kbit/s upstream data rate Top 10 improvements of ADSL2 (G.992.3) (5) : Top 10 improvements of ADSL2 (G.992.3) (5) Higher Layer Adaptation Support of IMA for ATM based ADSL (bonding) Support of Packet based ADSL (e.g., Ethernet) Home Installation Architecture includes in-line filters (splitterless) Multiple ATU-R connected to the line (Hi-Z state) Backwards compatibility/deployment of G.992.3: Backwards compatibility/ deployment of G.992.3 G.handshake (G.994.1) allows to indicate support of multiple ITU-T ADSL (and other) Recommendations: G.992.1, G.992.2, G.992.3, G.992.4 Implementations are expected (not mandated!) to support G.992.1/2 and G.992.3/4 for interoperability with existing deployments. G.992.1/2 equipment practice (e.g., DSLAM port density and power consumption) is expected not to be impacted by multimode support for G.992.3/4. PSD Masks identical to G.992.1 for operation over POTS and ISDN, spectrum management and deployment considerations are the same as for G.992.1. The lite version: G.992.4: The lite version: G.992.4 Delta to G.992.3: functionalities are common to G.992.3 and G.992.4. Fast retrain replaced by Fast start-up. Power Management extended with low data rate state. G.992.3 operates with 128 tones, rather than 256 (PSD mask as in G.992.2). G.992.3 has operation over POTS (Annex A) and All Digital Mode with 32 upstream tones (Annex I), it does not have operation over ISDN. The Next Step: ADSL+ (G.adslplus): The Next Step: ADSL+ (G.adslplus) Increase of downstream data rates (maybe upstream) Delta to G.992.3 (no ADSL+ without ADSL2 !) Requirements need work ? Reach: better than VDSL (3 km?) ? More tones or Wider tone spacing ? Up to 2.2 MHz or up to 3.4 MHz (1st VDSL band) ? PSD masks, SC with VDSL, with CO-ADSL ? CO application, RU application Target to consent in Jan 2003 SG15 meeting The Next Step: SELT: The Next Step: SELT Single ended line testing (ADSL2 has double ended LT). From DSLAM: trouble resolution, not line pre-qualification. Interferences as cut line, shorted line, excessive loss, excessive noise, modem not connected or not working. Items suggested for terms of reference on SELT: work would be technology generic where appropriate and DSL technology specific where needed premature to decide if a new, separate, Recommendation is produced minimizing DSL equipment complexity should have precedence over optimizing functionality
Introduction; 2002 DSLAM Market. Worldwide DSLAM Port Shipments by Region; ... ADSL2+ Symmetrical DSL. HDSL (High Bit Rate DSL) HDSL2 (2nd generation HDSL)
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