Power spectral density masks for ADSL+

Abstract

Disclosed herein are various power spectral density (PSD) masks for spectral shaping of an asynchronous digital subscriber line (ADSL) overlap and non-overlapped spectrums via an integrated digital services network (ISDN) or plain old telephone system (POTS).

Description

CROSS REFERENCE TO RELATED APPLICATIONS:[0001] The present invention claims benefit of U.S. Provisional Application No. 60 / 398,124, filed Jul. 25, 2002, and U.S. Provisional Application No. 60 / 399,135, filed Jul. 30, 2002, the entireties of which are incorporated by reference herein.FIELD OF THE PRESENT INVENTION[0002] The present invention relates generally to asynchronous digital subscriber line (ADSL) systems, and in particular, to systems and methods for improving transmission performance in such systems.BACKGROUND OF THE PRESENT INVENTION[0003] With the increasing popularity of the Internet and other content-heavy electronic communication systems, there has been a substantial need for reliable and affordable high bandwidth mediums for facilitating data transmissions between service providers and their customers. In relation to the requirement that such mediums be affordable to consumers, it was determined that the most cost-effective manner for providing service to customers wa...

AI Technical Summary

Benefits of technology

[0016] In a first embodiment, an overlap frequency spectrum is implemented with transmissions made in accordance with Annex C to the G.992.1 Recommendation. In particular, systems implementing both overlap and non-overlap modes are fully supported by the existing G.992.1 Recommendation. Further, the partial overlap spectra of Annex C (FBMsOL, DBMsOL) for providing reduced NEXT interference are defined as a subset of the full-overlap spectrum defined in Annex A of G.992.1. Accordingly, there is no need to define new annexes for operation in overlapped modes for DBM as well as for FBM as it is well supported by the current Annex C definition. In addition, the use of the existing code points for implementing the proposed overlap modes does not violate the operation of the current systems and also enables interoperability with the current frequency division multiplexing (FDM) systems thereby ensuring backward compatibility with current FDM systems.

[0030] In an asynchronous digital subscriber line (ADSL) system comprising a central office High Speed ADSL Terminating Unit (HSTU-C) in bi-directional discrete multitone (DMT) communication with a remote High Speed ADSL Terminating Unit (HSTU-R), a method for improving handshake detection robustness is provided. The method comprises transmitting handshake signaling via a first subset of carrier sets of a DMT transmission bandwidth between the HSTU-C and HSTU-R at a first symbol rate, determining a presence of near end cross talk (NEXT) in a second subset of carrier sets of the DMT transmission bandwidth, and transmitting the at least one handshake symbol via the second subset of carrier sets at a second symbol rate so that at least one sub-symbol of the at least one handshake symbol transmitted over the second subset of carrier sets is substantially unaffected by near end cross talk. The first symbol rate preferably is 539.0625 symbols per second and the second symbol rate preferably is 269.53125 symbols per second. The second subset of carrier sets preferably includes carrier sets C43 and / or A43.

Problems solved by technology

For example, due to noise and other interference generated by these ISDN systems, as well as the potential adverse impact ADSL deployment may have on these existing systems, relatively severe performance limitations have been placed upon ADSL implementation in these regions.

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