Intro to xdsl part 1

ADSL (full rate)

• Asymmetric - high rate DS lower rate US
• Originally designed for video on demand
• Almost retired due to lack of interest
• …but then came the Internet
• Studies show DS:US should be about 10:1
• full rate ADSL 512-640 kbps US, 6-8 Mbps DS G.lite 512 Kbps US, 1.5 Mbps DS
• ADSL could mean All Data Subscribers Living

G.lite

• Splitterless ADSL, UAWG
• ADSL compatible DMT compatible using only 128 tones
• 512 Kbps US / 1.5 Mbps DS
• Still much faster than V.34 or V.90 modems
• No splitter required!
• Certain features removed for simplicity
• simpler implementation (only 500 MIPS < 2000 MIPS for full rate)

ADSL2

• ADSL uses BW from 20 kHz to 1.1 MHz
• ADSL2 Increases rate/reach of ADSL by using 20 kHz - 4.4 MHz
• Also numerous efficiency improvements
• better modulation
• reduced framing overhead
• stronger ECC
• reduced power mode
• misc. algorithmic improvements
• for given rate, reach improved by 200 m
• 3 user data types - STM, ATM and packet (Ethernet)
• ADSL2+ dramatically increased rate at short distances

VDSL

• Optical network expanding (getting closer to subscriber)
• Optical Network Unit ONU at curb or basement cabinet
• FTTC (curb), FTTB (building)
• These scenarios usually dictates low power
• Rates can be very high since required reach is minimal!
• Proposed standard has multiple rates and reaches

VDSL2

• VDSL uses BW of 1.1 MHz - 12 MHz (spectrally compatible with ADSL)
• VDSL2 uses 20 KHz - 30 MHz
• new band-plans
• increased DS transmit power
• various algorithmic improvements
• borrowed improvements from ADSL2
• 3 user data types - STM, ATM and packet (pure Ethernet)

HPNA (G.PNT)

• Studies show that about 50% of US homes have a PC
• 30% have Internet access, 20% have more than one PC!
• Average consumer has trouble with cabling
• HomePNA de facto industry standard for home networking
• Computers, peripherals interconnect (and connect to Internet?)
• using internal phone wiring (user side of splitter)
• Does not interrupt lifeline POTS services
• Does not require costly or messy LAN wiring of the home
• Presently 1 Mbps, soon 10 Mbps, eventually 100 Mbps!