1 / 16

ADSL technology

ADSL technology. Access Networks lectures 2008/09. Broadband Network (Internet). Wiring Distribution Frame). Customer Premises Wiring. ... once more. ADSL. = Assymmetric Digital Subscriber Line inmodulation band (not baseband)

ncain
Télécharger la présentation

ADSL technology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ADSL technology Access Networks lectures 2008/09

  2. Broadband Network (Internet) Wiring Distribution Frame) Customer Premises Wiring ... once more...

  3. ADSL • = Assymmetric Digital Subscriber Line • inmodulation band (not baseband) • - ANSI standards (T1.413 of T1E1.4 group), ETSI (european requirement added to T1.413), ITU (groups of standards ITU-T G.991, 992, 995 etc. – they are downloadable from : ITU - publications – ITU-T) • Specifications: • high bit rate transmission + telephone (and also analog) connection, or ISDN • max. downstreamfrom 1,5 to 8 Mbps / max. upstream from 16 to 832 kbps (basic ADSL system) – various data speeds in dependence from user distance • freq.band up to 1,1 MHz, DMT modulation scheme (Discrete Multitone Transmission), max. 256 DMT channels, each is 4 kHz wide • for analog teleph.- lower 4 kHz, for ISDN up to 80 kHz (if there is ISDN transmission, the band for digital data is reduced) • reach - 5,5 km • frame transmission by means Cu- lines • Full / Lite versions

  4. ISDN-BRA Frequency Analog teleph.signal Fig. 1 ADSL spectrum with various variants [2] ADSL variant speed number of subchannels from to number of subchannels from to speed only data Tab.1 Comparison of ADSL variants

  5. Downstream POTS Upstream Frequency Fig. ADSL spectrum in frequency multiplex Downstream Upstream POTS Frequency Fig. ADSL spectrum with echo compensation

  6. ADSL and ISDN Upstream Downstream Frequency Basic Access (4B3T link code) Frequency Basic Access (2B1Q link code) Frequency

  7. ADSL

  8. btw., relation between bandwidth and data speed: Shannon-Hartley theoremafor information capacity of channel with both digital signal with mean power S and additive Gauss noise with mean power N. Bandwidth of channel is B [Hz]. [bps] ... channel information capacity B ... bandwidth[Hz] S ...power of signal in the given band B [V2 or W] N...powerof noise in the given band B [V2or W] S/N . .. signal–to-noise ratio [-] (we know already SNR[dB] =10 log (S/N) )

  9. LF symmetrical pair HF Fig.2 Typical termination of ADSL line on the user side Fig.3 ADSL line configuration with splitters user Provider user line Data network ATU-C =ADSL transceiver unit at the central office, ATU-R .....at the Remote home or business

  10. Splitter

  11. filtre DP a HP ATU-C (ATU-R) =ADSL Transceiver Unit (on the user side) koncentrator and/or switch (switching array) multiplexor/demultiplex. PHY = physical interface Fig.4 Reference model of ADSL in comparison to general xDSL model [6]

  12. transmitted data bit sequence securing scrambler RS coder trellis coder carrier mapping dig.QAM power spreading CP adding D/A conversion analog transmit.part data interface analog section line hybrid Echo cancelling A/D conversion analog receiver part received data secured bit sequence decoding Fig.5 Functional scheme of ADSL modem (and steps of data treatment …)

  13. ADSL2+ 2,2 MHz 1,1 MHz Up to 18,000 feet (5.5 km) Up to 25 Mbps down Up to 1 Mbps Upstream Fig.6ADSL 2+ system

  14. ADSL2 • ITU-T G. 992.3, .4 • 2nd generation of ADSL standard • downstream - up to 12 Mbps • DMT modulation • bandwidth - up to 2,2 MHz • but: shorter reach (only from 1,5 to 2 km) ! • CVoDSL • ADSL2 + (fig.6) • ITU-T G. 992.5 • downstream - up24 Mbps • bandwidth - up to 2,2 MHz (512 subchannels DMT,each 4kHz wide, up to 2,2 MHz) • full data speed only in reach of max. 1,5 km from DSLAM (!)

  15. RE-ADSL = Reach Extended ADSL • ITU-T G.992.3 – Annex L (it is annex to ADSL2 standard) • optimalized DMT channels with the goal of larger length (manipulation with PSD of some channels  their higher throughput • dedicated to long lines (not for short ) – up to 5,5 km with the same date speed as in ADSL2 • RADSL = Rate Adaptive DSL • - it is in development • - both symetrical and assym.transmission • transmission speed is adaptive (it depends on transmission conditions and distance) • down 1-12 Mbps / up 128kbps-1Mbps • DMT or CAP (and QAM) are supposed • - for applications without synchronization requirements (IP services, ATM, Frame Relay) • Bonded ADSL • - combines (bonds) 2 or more (up to 32) Cu-pairs for higher or extreme data speeds (for big and reach  companies)

  16. Literatúra [1] Vaculík: Prístupové siete. ŽU v Žiline, 2000. [2] J. Vodrážka: Přenosové systémy v přístupové síti. ČVUT, 2003. [3] T. Anttalainen: Introduction to Telecom. Network Engineering, Norwood (USA - MA), 2003. [4] L. Harte: Introduction to Digital Subscriber Line (DSL): Technologies, Operation and Systems. ALTHOS, 2005. [5] ITU_T G.995.1 Recommendation, Geneva, 2001.

More Related