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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

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Wiring a small piece of the world

Wiring (a small piece of) the world

Target and interim solutions

W. Warzansky

Telefonica I+D

Access network target architectures
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


    with ATM-PP as a variety.

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

Present situation
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
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


Evolutionary paths
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

Step 1 use of cable modems
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 reuse1
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
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
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

Evolution paths for fibre based on
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
Enhanced SDH based AON

Combined ONU







n x 2Mbit/s















From existing copper to atm
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
Step 1 (900 Euros/client)

From copper to atm step 2
From copper to ATM: Step 2

  • Option 1: Overlay ATM-PON for BB services

    Price: 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
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
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

Interim solutions
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
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
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


  • 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.

Conclusions i
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
Conclusions (II)

  • Once way to reduce capital investment is to reuse

    existing access infrastructure as much as


  • EURESCOM has done this, studying how existing

    access networks can be made to evolve gracefully

    to ATM-PON, the already identified target access


Conclusions iii
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