triban workshop bern, 17-19 november 1998 wiring (a small piece of) the world target and interim...

TRIBAN WorkshopBern, 17-19 November 1998

Wiring (a small piece of) the world

Target and interim solutions

W. Warzansky

Telefonica I+D


Access network: target architectures

• From conclusions of former EURESCOM work,

later adopted by FSAN, it is considered that the

access network target architecture for broadband

interactive services in residential areas is

ATM-PON with ATM-PP as a variety.

• Full PON specification is now available (ITU-T G.983)


Present situation

• ATM-PON/PP deployment has not started, mainly because there is not yet a significant market for broadband interactive services.

• But there are already many access networks with a real, or latent, broadband capability:- Plain copper (POTS)

- Fibre access networks (active and passive)

- HFC


Evolution paths towards B-ISDN access networks

• EURESCOM (P-614) has performed a study of

possible (recommended) evolution paths from

existing access networks towards ATM-PON/PP,

with the aim of determining the possible

reutilization of part of the existing access

infrastructure.


Evolutionary paths

• From HFC to ATM-PON

• From existing fibre to ATM-PON/PP

• From existing copper to ATM-PON

• From existing copper to ATM-PON through LMDS

• ... and also, some interim solutions


From HFC to ATM-PON: step 1

Coaxdrop

PON

ONU

ANN/LTHE

duplexer return channel

E/OO

E/OO

TVset

set topbox

CPN

Cablemodem

Cablemodem

Port

To PC or LAN


Step 1: use of cable modems

• Deployment of cable modems and return path amplifiers

• Penetration level it can satisfy: around 1%

• Price tag: 670 Euro/user connected


Step 2: B-ISDN ONUs and coax reuse

Coaxdrop PON

(TV)ONU

LTHE

TVset

set topbox

CPN

NT

To LAN

OLTB-ISDN

ONU

Combiner


Step 2: B-ISDN ONUs and coax reuse

• Deployment of B-ISDN ONUs and NTs with coax line cards, combiners and return amplifiers (e.g., 620-860 MHz).

• ONUs fed by spare fibres or WDM

• Penetration level it can satisfy: up to 10%

• Price tag: 1150 Euros/user connected @penetration of 10%


Step 3: Enhancement of coax drop

• Upgrade of coax drop by replacing junction and distribution boxes. Deployment of extended band return amplifiers (e.g. 1-2 GHz).

• Price tag: increment from step 2 of 162 Euros/user connected.


From existing fibre to ATM-PON/PP

• Existing active fibre access networks are not standardised. There are many proprietary solutions deployed.

• Three starting situations have been considered:- PDH based active optical networks

- SDH based active optical networks

- Narrow band passive optical network


Example of SDH based AON

OLT

STM-1/ 4FMUX

FP2

drop sg.feeder

sectiondistribution segment

NT

STM-1

STM-1/4

L E X

SNI

A

D

M

A

D

M

A

D

M

FMUX

FP2

FMUX

NT

NTMLLN


Evolution paths for fibre based ON

• NB-PONs evolve naturally to ATM-PONs

• The recommended evolution of PDH AONs is to overlay an ATM-PP. Evolution to SDH is very expensive.

• For SDH based AONs:- Add B-ONU to N-ONU. Provide ADSL interfaces

- Overlay ATM-PP to ADMs


Enhanced SDH based AON

ATM

STM-1

POTS MUX ISDN II

xDSL ATM MUX

ATM NTxDSL

ONU-B

ONU-N

SNIs

STM-1

OLT-B

OLT-N

UNIs

Combined ONU

n x 2Mbit/s

Terminalmultiplexer


From existing copper to ATM

• xDSL from the exchange is NOT a long term solution- The bandwidth achievable in copper links is low

(probability of provision 15%)

- Noise from HDB3 (and others)

- Copper OAM costs are on the rising

- Very long payback time for new installation cables

- For high penetrations xDSL is more expensive than fibre

- Small number of DSL lines per cable


Step 1 (900 Euros/client)

V

Drop SegmentDistribution Segment

FP1

Twisted Pairs

Twisted Pair

Twisted Pair

MDF

DLCOptical Fibre

DLCODF

NB

BB

FP2

U T

DP

DP

DP

DP

DPATU-R+

SplitterMUX

DSLAM

FP2

MUX

POTSsplitters

DPATU-R+

Splitter

ATU-R+

Splitter

ATU-C


From copper to ATM: Step 2

• Option 1: Overlay ATM-PON for BB servicesPrice: 1150 Euros/client @10% penetration

• Option 2: Integrate NB and BB transport- Implement V5.x protocols in the ONU and use AAL1 for

transparent transport of 2 Mbit/s frames to NB switch

- Implement AAL2 at the ONU• Efficient bandwidth usage through VBR

• Supports voice compression

• Multiple voice channels on a single ATM connections

- Price: add 700 Euro/client @10% penetration


From copper to ATM: step 3

• The third step is to go all the way to ATM-PON with fibre deeper into the network and ONUs closer to the customer than in step 1

• Price: 1300 Euros/client @10% penetration


LMDS as an intermediate solution

• Starting situation: existing copper

• First step: LMDS

• Second step: augmenting LMDS

• Third step: ATM-PON

• The advantages of LMDS are those of wireless systems


1% 2% 3% 4% 5% 6% 7% 8% 9%10

%

11%

12%

13%

14%

15%

0%

30%

60%

90%

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

Cost Per Connected

Penetration

Interactivity

LMDS Cost: 1 Base Station


LMDS cost @10% penetration

10% Coverage

0

500

1,000

1,500

2,000

2,500

3,000

3,500

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Interactivity


Interim solutions

• Set of unconventional systems to deliver

somewhat more than NB but less than BB (e.g.,

200- 1000 Kbit/s)

• Some of these “interim solutions” look at

circumventing the existing fixed access

infrastructure, . . ., and the incumbent operator


Reflections on interim solutions

• Most of these “interim solutions” looks dubious,

at least now.

• Consequently, we heartily recommend them to

new entrant operators, though it seems unlikely

they will follow the recommendation.

• It seems advisable to keep an eye on these

solutions, because you never know what might

turn up


Low-cost XDSL implementations

• ADSL- wide variety of implementations and vendors

- HDSL (1- or 2-pairs) as symmetric counterpart

- medium/high maturity, medium cost, service limitations

- mostly rate adaptive and ATM based!

- provide both ATM and ATM interfaces

- typically PPP over AAL5

• CDSL (DSL lite)- widely discussed, little known

- uncertain maturity, low cost, major service limitations

- probably IP based


Example 1: Netspeed, key: modem sharing

POTS splitter

ATU-RDSLAM

ATU-C

ATU-C

ATU-C

Local Exchange Customer Premises

DSLAM = Digital Subscriber Line Access Multiplexer

ATU-C = ADSL Terminal Unit - Central side

ATU-R = ADSL Terminal Unit - Remote side

Off hookdetector

&Switch

Controller

n x m

n = number of ATU-C

m = number of ATU-R

n < m


Example 2: Paradyne, point-to-multipoint

DSLAM

ATU-C

ATU-C

ATU-C

ATU-R

ATU-R

ATU-R

sharedprinter

web server

Home Working

PC

4 kHz 20 kHz 100 kHz

broadband signalPOTS

DSLAM = Digital Subscriber Line Access MultiplexerATU-C = ADSL Terminal Unit - Central side

ATU-R = ADSL Terminal Unit - Remote side



Example: CAIS system

NT

NT

NT

NT

OverVoiceEthernet

Hub

CC

MDF

twisted pair

fiber optical


CC = Cross Connect

MDF = Main Distribution Frame

NT = Network Termination

Router


Powerlines

• Widely discussed, little proven, possibly expensive

• IP based, to overcome noise problems

• Further concerns- security aspects: maintenance of 240 V lines is

dangerous;

- privacy aspects: it is a physical bus, everybody receive everything (like in HFC networks);

- electromagnetic emission: possible noises produced by powerline systems affecting other electric devices (e.g. complaints from HiFi users);

- regulatory aspects: e.g. ownership of the lines.


Example: Nortel/Norweb approach

HV current

OLT

TxRx

Controller

TxRx

Powering

meter

TxRx

NT

NT

NT

NT

building meter

filter for inserting or extracting the BB signal

splitter

LV current

Router

Local Exchange Base Station and transformer

HV/LV transformer

power lines

Customer Premeses

low voltage power line (Cu)

high voltage power line (Cu)

fiber optic

coaxial cable

HV/LV = High Voltage / Low Voltage

OLT= Optical Line termination

NT = Network termination


Conclusions (I)

• The residential broadband interactive services

market has not yet arrived.

• One of the reasons for this (among others) is the

high capital investment required, in an

environment where capital investment goes to

acquisitions and home networks are under

intensive pressure to reduce costs.


Conclusions (II)

• Once way to reduce capital investment is to reuse

existing access infrastructure as much as

possible.

• EURESCOM has done this, studying how existing

access networks can be made to evolve gracefully

to ATM-PON, the already identified target access

network.


Conclusions (III)

• Another activity performed by EURESCOM is the

keeping of an eye on new or “interim” solutions,

some of them a bit weird, because it might

happen that one of them might strike the right

combination of price/market demand

triban workshop bern, 17-19 november 1998 wiring (a small piece of) the world target and interim...

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