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 Monday, 02 July 2007

A second standard in a new group of Recommendations from ITU-T's Study Group 15 extends the distance at which multi-vendor DWDM systems can be deployed from 80 to four or five hundred kilometres.

The first standard in the series gave network operators the ability to deploy multi-vendor dense wavelength division multiplexing (DWDM) systems in a metro environment. The new Recommendation extends this to cover regional environments by taking into account the use of optical amplifiers and their potential to create 'optical noise'.

WDM technology is used by the owners of optical fibres to maximise their capacity. The technology achieves this by simultaneously operating an optical fibre pair at more than one wavelength and uses optical amplification to increase transmission distances as well as optical add/drop multiplexers to increase the flexibility of the network. Since operators wish to maximize their cable plant investments and deploy increasingly bandwidth hungry services in a multi-vendor environment, standards development in this field is seen as crucial.

The Recommendation defines values for single-channel optical interface parameters of physical point-to-point and ring DWDM applications on single-mode optical fibres through the use of the "black-link" approach. The black-links covered by this follow-on Recommendation may contain optical amplifiers.

The transport network of most operators is based on the use of equipment from a variety of different vendors. Previously, for those parts of the network involving DWDM optical transmission, this has been achieved via the use of optical transponders which convert the single channel interfaces like those defined in ITU-T Recs G.957 G.691, G.693, G.959.1 into DWDM wavelengths suitable for the particular vendorís proprietary system. With the optical interfaces standardized in new G.698.2 operators can directly connect a wide variety of equipment to the DWDM line system without the need for those additional short reach transmitter and receiver pair per channel (eliminating the transponders) with obvious associated cost savings.

Monday, 02 July 2007 08:36:16 (W. Europe Standard Time, UTC+01:00)  #     | 
 Thursday, 28 June 2007
Meetings of Study Group 2 - Operational aspects of service provision, networks and performance

Geneva, 30 October - 8 November 2007

Registration Form

See TSB Collective-letter 6/2 for more information.

Study Group 2 Home

Thursday, 28 June 2007 10:48:44 (W. Europe Standard Time, UTC+01:00)  #     | 
 Wednesday, 27 June 2007
Meetings of Study Group 4 - Telecommunication management

Geneva, 28 August - 7 September 2007

Registration Form

See TSB Collective-letter 6/4 for more information.

Study Group 4 Home

Wednesday, 27 June 2007 11:00:23 (W. Europe Standard Time, UTC+01:00)  #     | 
 Wednesday, 20 June 2007
Meetings of Study Group 19 - Mobile telecommunication networks

Geneva, 21 September 2007 (afternoon)

Registration Form

See TSB Collective-letter 7/19 for more information.

Study Group 19 Home

Wednesday, 20 June 2007 09:31:39 (W. Europe Standard Time, UTC+01:00)  #     | 
 Monday, 18 June 2007

Another step towards all optical networks (AON) has been achieved with the consent of the new Recommendation G.680 by ITU-T's Study Group 15.

The Recommendation will allow operators to take optical add/drop multiplexers (OADMs) and photonic cross-connects (PXCs) from different vendors and integrate them in to an all optical network without having to add expensive optical/electrical/optical conversion (O/E/Os).

This achievement is made possible as the Rec gives operators a way to evaluate the end-to-end quality of a signal where photonic cross-connects (PXC) and optical add/drop multiplexers (OADMs) are deployed. In addition, experts say that the evolution towards an AON could significantly reduce costs for operators by reducing the need for costly optical/electrical/electrical (O/E/O) conversion. As optical transport networks (OTN) evolve, the number of - expensive - O/E/O conversions within their boundaries is coming down.

The two main reasons for the reduction in the number of O/E/O conversions are that DWDM systems are becoming capable of carrying light signals for thousands of kilometers without electrical regeneration and that PXCs and OADMs are becoming available with the capacity, space requirements, power consumption, reliability and cost, suitable for their use in the telecommunication networks. With this evolution experts predict that AONs could extend to all potential routes of the backbone network of a medium size country - optical paths up to around 2,000 km.

The Recommendation defines a "degradation function" of optical network elements (ONEs) such as photonic cross connects (PXCs), optical add-drop multiplexers (OADMs), etc. making up an optical network. It enables the degradation of the signal quality in an all-optical network consisting of ONEs including DWDM line segments to be assessed.

Monday, 18 June 2007 09:14:28 (W. Europe Standard Time, UTC+01:00)  #     | 

An upgrade to a widely used specification for fibre optic cables will allow the simpler deployment of Gigabit Ethernet (GbE) in FTTH applications up to 500 m link distance. The original Recommendation ITU-T Rec G.651 provided specifications for multimode fibre which is currently widely deployed for data communications, but not for telecoms.

The work was initiated given two observations; the cost disparity between telecom and data networks, where high speed GbE telecom equipment is often far more expensive than datacom equipment; and the economics of rolling out FTTH into multi-tenant (apartment) buildings where there is a high subscriber density. Ethernet is increasingly seen as an end-to-end technology.

Similar to recently published Rec G.657 on single mode fibre, Recommendation G.651.1 allows for increased cable flexibility. This increased flexibility in a fibre optic cable means that operators can follow tighter corners in buildings and can worry less if cables / fibres are laid with a sharp bend. This all makes installation work more engineer friendly leading also to less re-work. Moreover the closures for fibres can be half the size, important where space is at a premium especially in multi-tenant buildings.

G.651.1 retains many of the key characteristics of its well known predecessor. However manufacturing tolerances and transmission characteristics have been improved significantly. In addition, it has been harmonized fully with relevant IEC standards.

Monday, 18 June 2007 09:10:50 (W. Europe Standard Time, UTC+01:00)  #     |