VDSLVDSL

Access NetworksAccess Networkslectureslectures 2008/09 2008/09

ĽĽ.. MacekovMacekováá – KEMT – FEI –TU -KE – KEMT – FEI –TU -KE

30 MHz

up to 52 Mbps

split Upstream and Downstream

Fig.1 – VDSL architecture – max. downstream only to 300 m ([6],

variable freq.bands

up to 1,5 km

Data up

Data up

Data down

Data down

VDSL class Service type

Downstream speed[Mbps]

Upstream speed[Mbps]

Reach – best- / worst one[m]

I(asymmetric)

A4 23,268 4,096 995 / 453

A3 14,464 3,072 1344 / 729

A2 8,576 2,048 (E1) 1691 / 789

A1 6,4 2,048 (E1) 1791 / 843

II(symmetrical)

S5 28,288 28,288 298 / 212

S4 23,168 23,168 397 / 261

S3 14,464 14,464 845 / 575

S2 8,576 8,576 1294 / 820

S1 6,4 6,4 1444 / 876

Tab. 1 Data speeds and reach by ETSI (Europe); for wires Φ 0,4 mm

Fig.2 General reference VDSL model (by ITU-T) [1]

Fig.3 Functional reference model VTU-x by ITU -T [1]

Fig.4 … by ITU [1]

Fig.5 Symmetrical and asymmetrical VDSL services

ISDN or POTS

ISDN or POTS

VDSL down stream

VDSL down stream

VDSL upstream

Asymmetrical traffic

Symmetrical traffic

VDSL upstream

frequency

frequency

Fig.6 DMT – VDSL spectrum (in combination with analog telephone) [7]

frequency

telephone

spec

trum

Fig.7 VDSL downstream (DS) and upstream (US) subbands alocation – generally [1] - see next slide...

Fig.8 The different frequency plans for VDSL by ITU [1] (Opt = Optional (yes/no, DS/US)

Tab. 2 An example of VDSL mask in downstreams DS1,DS2 described in standard ITU-T G.993.1

Fig. 9 VDSL transport modes possibilities [2]

STM – synchronous transport mode

Fig.10 DSL network [6,8]

- ITU-T G.933.2 (2006)

- enhanced VDSL version – the goal: do not lose customers in competitive with “cable” VoIP, Internet, digital TV and VoD-HD providers

- freq, band up to 30 MHz

- symmetric up- and down- streams each of 100 Mbps (aggregate data speed 200 Mbps)

- reach to 2,5 km ( US0 band - to 276kHz, EC, TEQs)

- several profiles

- Zipper DMT (DMT based duplex – subcarrier bands, each 4 or 8kHz wide – from 2048 to 4096 bands – see next fig.) – allocation of subcarriers and data speed adaptation accordingly to immediate requirements of applications on the both sides of line

- trellis encoding

- STM and PTM supporting

- interoperability with ADSL devices, there are also several profiles (8) for different applications – see tab. 3 and fig.12 in the next slides

VDSL2

Fig. 11 VDSL2 spectrum utilization and comparison with ADSL2 and ADSL2+

Tab. 3 VDSL2 profiles

Fig.12 VDSL2 profiles in comparison with ADSL and ADSL2+

Profile

Bandwidth (MHz)

Number of

carriers

Carrier bandwidth

(kHz)

Power (dBm)

Max. Throughput

(Mbit/s, downstream)

8a 8,832 2048 4,3125 +17,5 50

8b 8,832 2048 4,3125 +20,5 50

8c 8,5 1972 4,3125 +11,5 50

8d 8,832 2048 4,3125 +14,5 50

12a 12 2783 4,3125 +14,5 68

12b 12 2783 4,3125 +14,5 68

17a 17,664 4096 4,3125 +14,5 100

30a 30 3479 8,625 +14,5 100

Tab. 4 VDSL2 profiles [Wikipedia]

Fig. 1 ones more comparison ADSL and VDSL: data speeds and reach (4500 f = 1,47 km, 18 000 feet=5,5 km)

other xDSL systems

FDSL – fiber DSL (but also other relevances)

[5]

Fig.15 Using fiber to span long distance; hybrid technology (optical / copper lines)

PDSL

[5]

- it was described already

Fig.16 Architecture of BDSL technology [4]

BDSL – Broadcast DSL

- it is dedicated for distribution of more TV (up to several tens) channels, which share transport medium (twisted pairs) with analog teleph. line (point-to-multipoint technology)

Analog. signals are digitized, and together with digital TV channels are compressed. There are used 3 subcarriers – 40 kHz, 80 kHz and 1,2 MHz..., DSLAM; ATM technology

Subscriber lines

- standard submitted to Committee T1E1.4,

References

[1] ITU-T G.993.1 Recommendation, 2004

[2] W. J. Goralski: ADSL and DSL Technologies. Sec. Edition.Osborne Mc.Graw-Hill, 2002.

[3] ITU-T G.933.2 Recommendation, 2006.

[4] Vaculík: Prístupové siete. ŽU v Žiline, 2000.

[5] J.Dúha, P. Podhradský, P. Trúchly: Technológie v prístupových sieťach a procesy ich integrácie do NGN. (Projekt: NGN- multimédiá, multimed.ICT technológie,... .) Bratislava, 2007.

[6] L. Harte: Introduction to Digital Subscriber Line (DSL): Technologies, Operation and Systems. ALTHOS, 2005.

[7] K.Blunár, Z. Diviš: Telekomunikačné siete, časť IV..- skriptum ŽU v Žiline, 2000.K.Blunár, Z. Diviš: Telekomunikačné siete, časť IV..- skriptum ŽU v Žiline, 2000[8]http://www.cisco.com/univercd/cc/td/doc/product/dsl_prod/gsol_dsl/dsl_arch/gdslarch.htm#1002608[9]http://findarticles.com/p/articles/mi_m0NUH/is_10_37/ai_107759816/pg_1?tag=artBody;col1