xDSL Technologies

1. xDSL Technologies Access Networks lectures 2008/09

2. Introduction • Some notes and new terms: • PSTN and Internet • digital / analog • frequency bands, bandwidths • busy time of circuit • bandwidth, delay, latency • utilizing of twisted pairs (of metallic networks) • several forms of DSLs xDSL • ‘bonded channels’ • statistical multiplexing • and others – see next pages

3. Fig.1Shared transport of both voice and data

4. Fig.2 „Digital – only“DSL transmission

5. data speed [Mbps] year Fig.3 History of DSL technology

6. xDSL VDSL PDSL FDSL HDSL group ADSL group standards: VDSL variations: VDSL2 VDSLPlus TotalVDSL standards HDSL HDSL2 variations: MVL SDSL MDSL IDSL • variations • 1-MPEG modem • CDSL • EZ-DSL • eXtremeDSLMAX • FasADSL standards ADSL RADSL G.lite ADSL2 ADSL2+ RE-ADSL2 Fig.4 Review of xDSL technologies

7. Tab.1 Review of xDSL technologies andtheir specifications[3]

8. Fig.5 DSL in local loop (splitter = LF filter – it devides off voice channeland reroutes it into PSTN)

9. IDSL (ISDN DSL) - standard ITU – T I.430, european ETSI ETR 80 Digital Only 144 kbps Down 144kbps Up Fig.6IDSL system

10. Specifications of IDSL: • … • …

11. HDSL group

12. HDSL synchro -group data blocks 1st pair 2nd pair H - HDSL service bits, S - stuffing symbols, Zn – identification bits of both pair and data block Fig.7 HDSLtime frame for 2-pairs system

13. service channel pairs 2 x 3 x Tab. Comparision of 2- and 3-pair HDSL (for unique pair HDSL is vp = 2320 kbps) HDSL link portion User side exchange unit terminal unit I – application interface M – mapping circuits C – common circuits of link termination REG – regenerator H – HDSL transmitter and receiver DLL = Dig.Local Line Fig.8 HDSL transmission principle

14. Fig. General reference configuration for xDSL systems [6]

15. Note: - HDSL can consist of 1, 2 or 3 pc. of H, REG and DLL, in the dependence from data transmission intensity - REG is not obligatory Fig. HDSL reference model vs. xDSL general reference model [6]

16. SHDSL application interface user interfaces not obligatory optional optional application indepence subbloc application depence subbloc application depence subbloc application indepence subbloc STU – SHDSL Termination Unit – Remote/Central PMD- Physical Media Dependent PMS-TC - Physical Media-Specific TC layer TPS-TC – Transmission Protocol-Specific ... SRU – repeater= SHDSL Regenerator Unit γR , γC –reference points of transportprotocol α, β – ref. point of application Fig .9 Functional model of SHDSL transmission chain

17. transport layer (e.g. SDH) transport layer (e.g. SDH) not specificated not specificated user data interface transmission medium link termination Fig.10 Layer reference model

18. Fig. SHDSL reference model in the relation to general xDSL ref. model [6]

19. Synchr. word user data block user data block user data block user data block stuffing bits head head head head 12 user subblocks Fig.11 SHDSL frame structure

20. HDSL2 • 2nd HDSL generation – not standardized • foregoer of SHDSL • MSDSL ...self study …

21. Other xDSL systems are described in next presentations.

22. References [1] V.Kapoun: Přístupové a transportní síte (Access and Transport networks, czech language). VUT v Brně, 1999. [2] Vaculík: Prístupové siete (Access Networks, slovak l.). ŽU v Žiline, 2000. [3] J. Vodrážka: Přenosové systémy v přístupové síti (Transport Systems in Access Natworks, czech l.). ČVUT, 2003. [4] T. Anttalainen: Introduction to Telecom. Network Engineering, Norwood (USA - MA), 2003. [5] L. Harte: Introduction to Digital Subscriber Line (DSL): Technologies, Operation and Systems. ALTHOS, 2005. [6] Recommendation ITU_T G.995.1