1 Access Networks Lecture /09 – w.t. Part 3. : Classification of Access Networks Lectures

2 AN: - users networks - hybrid n. (xDSL) - optical… - radio communications network - TV cable distribution system (network) - power lines communications network

3 Exchange MDF ED user distrib.frame network distr.frame track distr.frame Main distribution frame = MDF) connecting cable user c. (station line) network cable track cable Obr.3.1 Example of flexible users network [1] 3.1 Users networks (PSTN)

4 3.2 Hybrid networks -partially Cu and partially optical cables = optical feeder + transmission system for Cu-wires pair Obr. 3.2 Hybrid network architecture OLT ONU NT ODN ADSL VDSL Customer Local exchange (the services node) SNI UNI Cu-pairs

5 Fig several different xDSL systems – the new systems in original Cu net with different distances (reach, range) Cable distribution box End Cable distribution box Distribution cable Main cable LE Main Network

6 xDSL: IDSL = ISDN DSL (ISDN-BRA dig. user connection) HDSL – High bit rate DSL SDSL – Symmetric DSL (Single line DSL) VDSL - Very high bit-rate DSL ADSL – Asymmetric DSL then: - ADSL 2 - ADSL 2+ - RE-ADSL 2 - RADSL (DSL = Digital Subscriber Line)

7 Fig. 3.4 Telephone access + ADSL system ADSL Teleph. network High speed channel Control channel V -interfaceT - interfaces Network sideConnecting lineUser side LP LP – low pass filter HP – high pass filter

8 Fig. 3.5 ADSL system in Cu-connecting lines principle Telephone netw. /ISDN User station Splitter e.g. ATM netw ork PA – Access point T- interfaces S- interface Network interface Connecting line: basic trunk, e.g. with 10 pairs of Cu wires connecting line

9 ADSL specifications: - modems on each end of twisted pair....3 information channels, including basic teleph.service (POTS= Plain Old Telephone Service), filters - modems are consistent with basic frames T1, E1 (see Switching technology) - downstream speed – depends on : Cu-line length, wire diameters, bridged taps, crosstalks - Attenuation of line increases with both its length and frequency, decreases with increasing wire diameter (or cross-section) Data speed [Mbps]Diameter of wires [mm]Distance [km] 1,5 or 20,55,5 1,5 or 20,44,6 6,10,53,7 6,10,42,7 Tab.3.1 Requested phys. parameters of ADSL lines

10 VDSL Fig. 3.6 VDSL system in hybrid network - architecture - statistical multiplex:... (see also fig.3.2 and 3.3) Telephone netw. /ISDN Cable branching Splitter T- interfaces S- interface e.g. ATM net Network interfaces Cu-connecting line optical connecting line User station 300m-500m!

11 NameMeaningData speedType of connect ion ReachApplications DSLDigital subscriber Line 160kb/sSymmet rical ~5 km ISDN group, voice and data HDSLHigh Data Rate Digital Subscriber Line 2Mb/sSymmet rical 4-5kmno POTS, E1 LAN/WAN, Service access feeder plant. SDSLSingle Line Digital Subscriber Line 2Mb/sSymmet rical 3-4kmSame as HDSL + POTS ADSLAsymmetric Digital Subscriber Line 1.5 to 8Mb/s Down 128kb- 768kb Up Asymm etrical 3-6kmInterest access, video on demand, simplex video, remote LAN access, interactive multimedia. VDSLVery High Data Rate Digital Subscriber Line Mbp/s Down Mbp/s Up Asymm etrical kmSame as ADSL+ HDTV Tab. 3.2 Comparison of xDSL technologies

12 Service lines of ISDN - BRA - PRA

13 ISDN – line – for rarely connecting to the Internet [2] Fig. llustration of ISDN lines

14 Interfaces V5.x for user systems connecting Fig. 3.7 Architecture of the network with interfaces V5.x Users AN Local Exchange Transit network V5.x - interfaces between AN and exchange - are defined by ETSI and ITU (G.964/965) - they do not depend on outputs of differents AN types including radiowave AN - possibility of interconnecting networks of different operators - differences between V5.1 a V5.2:... - see next tab.and figure

15 Fig. 3.8 Example of architecture of AN with both interfaces V5.x V 5.1V x PCM 30/32 each with 2048 kbps16 x PCM 30/32 with 2048kbps It does not have concentration (only 1 line between exchange and AN) It can concentrate traffic and dynamically allocate time slots for users  connecting thousands users Static allocating of channelsDynamic allocating of channels – protocol BCC It does not allow connecting ISDN-PRA, only –BRA (15xPOTS+15xISDN,or 30xPOTS) ISDN-BRA aj -PRA Signalling without back-up…saving data in the case of failed channel Access device of AN Exchange channels Network of ren circuits

16 Obr. 3.9 V5.2 interface communications protocol  they support also analogue user lines - interfaces protocols - see fig.3.9 and 3.10 switching system control of access network Physical layer of access network Analogue user terminals

17 Fig.3.10 An example of process of creating and aborting connecting, which was initiated from dig. user line.(by protocol BCC-part od protocol V5.2 from end point of AN – request for dispose communications channel... -request for disconnect - data transmission (by onother protocol) KBPS-TE Communications process Access netw. Switching syst.

18 Referencie: [1] V.Kapoun: Přístupové a transportní síte. VUT v Brně, [2] Vaculík: Prístupové siete. ŽU v Žiline, [3] J. Vodrážka: Přenosové systémy v přístupové síti. ČVUT, [4] Wikipedia, structure.png#filehttp://en.wikipedia.org/wiki/Image:Tdma-frame- structure.png#file [5] G.Fairhurst: MAC. pages/mac.htmlhttp:// pages/mac.html [6] K.Blunár, Z. Diviš: Telekomunikačné siete, časť IV..- skriptum ŽU v Žiline, 2000.