Method and apparatus for reducing near-end crosstalk (NEXT) in d

Details Method and apparatus for reducing near-end crosstalk (NEXT) in d Method and apparatus for reducing near-end crosstalk (NEXT) in d

1997-12-23

2000-11-07

Chin, Stephen

Pulse or digital communications

Transceivers

Modems

375285, 375346, 370201, 370480, 370503, 379 9301, 379 9308, 379406, 379410, 379417, 455295, 455501, H04B 138, H04B 1500, H04L 516

Patent

active

061446955

ABSTRACT:
This invention reduces near-end crosstalk between identical discrete multi-tone (DMT-type) modems by introducing the following modifications to modems at a central office or a subscriber premises. The modifications include: a mechanism for aligning the frames of all modems at the central office (CO), a mechanism for aligning the frames transmitted by the subscribers' modems with the frames received by those modems, and lengthening the DMT frame to include a cyclic prefix. The cyclic prefix to a frame has been made longer than twice the maximum round-trip delay, that is, the delay between the central office and the most distant subscriber to be served. By making adjacent DMT carrier frequencies be orthogonal to each other, the aforementioned modifications will reduce both Near End Cross-Talk (NEXT) and Leakage-Excited Cross-Talk (LEXT). These benefits apply to modems at both the central office (CO) and subscriber ends of the communication path (for example, a high capacity twisted-pair wire).

REFERENCES:
patent: 5479447 (1995-12-01), Chow et al.
patent: 5519731 (1996-05-01), Cioffi
patent: 5521949 (1996-05-01), Huang et al.
patent: 5668802 (1997-09-01), Chalmers et al.
patent: 5673290 (1997-09-01), Cioffi
patent: 5680394 (1997-10-01), Bingham et al.
patent: 5887032 (1999-03-01), Cioffi
patent: 5970088 (1999-10-01), Chen
patent: 6009122 (1999-12-01), Chow
patent: 6014412 (2000-01-01), Wiese et al.
patent: 6044107 (2000-03-01), Gatherer et al.
American National Standards Institite, Standards Document--T1.413-1995; "Network and Customer Installation Interfaces--Asymmetric Digital Subscriber Line (ADSL) Metallic Interface"; Approved Aug. 18, 1995, pp.: cover page; two inside sheets; i-vi; 1-115.

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