Fred Howett - Nortel Networks OFTEL INTERNET FORUM - 1st Sept. 1999 Progress in NICC xDSL Task Group Fred Howett - Nortel Networks

Fred Howett - Nortel NetworksOFTEL INTERNET FORUM - 1st Sept. 1999

Progress in NICC xDSL Task Group

Fred Howett - Nortel Networks


Work of xDSL Task Group

• Established April 1998

Terms of ReferenceInvestigate and report on the technical aspects of:• Potential for DSL-Lite to be CPE in the UK• Possible DSL Interference issues

• mutual between xDSL technologies

• between xDSL and existing services (eg ISDN, POTS)


Task Group Membership

• Switch and terminal manufacturers (Alcatel, ECI Telecom, Ericsson, Fujitsu, Marconi, Motorola, NEC, Nortel, Racal, Siemens)

• Network operators(BT, Kingston, C&W, Worldcom)

• DTI (Telecoms + RA)

• BABT

• OFTEL


Results• 2 reports published in September 1998

- open issues identified

• NICC response to LLU Consultation - March 1999(above documents available on public NICC www site)

• Final Activities (published May 1999):• Conclusions Report

• Addenda to 2 reports issued in September 1998


Potential for DSL-Lite as CPE (1/3)

• Equipment expected to be available from mid 1999

• Standards mature (insufficient for vendor interoperability)

• multi-vendor interoperability not expected for some time

• Needs metallic path (no pair gain, line extender systems)

• Service issues (“best effort” - affect by customer’s wiring/CPE)

• Need CPE approval (no EC approval exists) • DSLAM may support ADSL ‘classic’ and DSL-Lite



• Potential service interactions • interference with existing POTS CPE (may be

reduced/prevented with filters)

• does not operate with some services (eg feature phone or payphones using out-band signalling, 30 k loop)

• does not operate with ISDN or other DSL systems

• Potential EMC issues (radio interference) due to unbalance of customer wiring



Conclusions• DSL-Lite equipment only just becoming available• significant push for DSL-Lite (particularly USA)• need level of multi vendor interoperability• need to resolve EMC and CPE approval issues

Above issues may take 1-2 years to resolve.


Possible xDSL Interference (1/2)

• Not all xDSL systems compatible

• Crosstalk forms key limitation

• Need for Frequency Plan/Deployment Rules Standards define PSD, but: • configuration options (eg power back-off)• need to consider deployment (eg reverse ADSL)

• non-standard systems exist


Possible xDSL Interference (2/2)

Frequency Plan/Deployment Rules• Need to define objective for cable fill• Dependent on access network architecture and cable type• Need to take account of existing services/transmission

systems and consider new generations of xDSL• Need to take account of CPE eg DSL-lite, Home LAN• Frequency plan based on PSD defined in standards• Highly complex task specialists + long time• This issue now being studied by standards fora

frequency planning tools


NICC LLU Response

Options 1 and 2

• would require the development of a spectrum management agreement for BT access network

• need a system for maintaining, policing and dispute adjudication on spectrum plan

• have Service Availability and Maintenance issues

Whilst Options 3,4 & 5 have other technical issues, spectrum management would be BT’s responsibility. Hence these options could allow market demand to be met earlier.


Future Work

• Meeting on 20/8/99 as response to OFTELs LLU proposals of July 1999

• xDSL TG to be forum for spectrum management

• TOR agreed

• Deliverables agreed


xDSL TG -Terms of Reference

• Develop a spectral management plan for BT’s copper access network

• Develop a set of rules relating to the characteristics and useage of the BT Partial Baseband Leased Circuit (PBLC)

• Liaise with OPF group re colocation and process issues


Timescale

• Agree TOR and workplan - August 1999

• Agree objective for developing spectral management and PBLC rules - Nov 1999

• Draft SM plan and PBLC rules - Apr 2000 for Phase 1, July 2000 for Phase 2

• TG approval of SM plan and PBLC rules - June 2000 for Phase 1, Sept 2000 for Phase 2


Spectrum management plan

• Two phases:-

• Phase 1 covers frequencies up to 1.1 MHz, whilst protecting higher frequencies. [this covers G.Lite and ADSL]

• Phase 2 covers frequencies up to 30 MHz [ie VDSL] and is 3 months behind Phase 1


Ongoing Issues

• International standards (ITU, ETSI, ANSI)

• EMC issues - draft MPT 1570

• R&TTE Directive

• Home networking equipment

Documents

Fred Howett - Nortel Networks OFTEL INTERNET FORUM - 1st Sept. 1999 Progress in NICC xDSL Task Group Fred Howett - Nortel Networks