ITU-T G.992.3 Annex L is an optional specification in the

ITU-T The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Comm ...

recommendation G.992.3 for ADSL2 titled ''Specific requirements for a Reach Extended ADSL2 (READSL2) system operating in the frequency band above POTS'', therefore it is often referred to as Reach Extended ADSL2 or READSL2. The main difference between this specification and commonly deployed Annex A is the maximum distance that can be used. The power of the lower frequencies used for transmitting data is boosted up to increase the reach of this signal up to 7 kilometers (23,000 ft). The upper frequency limit for READSL2 is reduced to 552 kHz to keep the total power roughly the same as Annex A. Since READSL2 is intended for use on long loops there isn't much (any) usable bandwidth above 552 kHz anyway. Although the standard development is completed and verified by the ITU, some owners of local loop networks don't allow this standard to be used because the high power can create audible Crosstalk. However, this standard is implemented nationwide by the incumbent local exchange carrier

France Telecom Orange S.A. (), formerly France Télécom S.A. (stylized as france telecom) is a French multinational telecommunications corporation. It has 266 million customers worldwide and employs 89,000 people in France, and 59,000 elsewhere. In 2015, ...

Frequency plans described in the various annexes

Tones are spaced apart by 4.3125kHz. In the Annex A, L and M frequency standards, POTS (analog

PSTN The public switched telephone network (PSTN) provides infrastructure and services for public telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local teleph ...

voice) occupies (what would be) tones 0-3, tones 4-7 are reserved for a ‘guard band’, and the upstream DSL transmission band uses tones 8-31 in Annex A and L, or 8-56 in Annex M. In Annex B,

ISDN Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Work ...

occupies tones 0-31, DSL upstream uses tones 33-56. Annex I and J are for DSL-only lines with no POTS voice or ISDN and upstream uses tones 0-31 (Annex I) or 0-56 (Annex J). Downstream transmission uses the highest tones from tone 33 for Annex A, I, L, or 60 for Annex B, J and M upwards.

External links

ITU-T Recommendation G.992.3 : Asymmetric digital subscriber line transceivers 2 (ADSL2)
Digital subscriber line ITU-T recommendations ITU-T G Series Recommendations Telecommunications-related introductions in 2002 Telecommunication protocols {{telecomm-stub

Frequency plans described in the various annexes

See also

External links