Method for interoperability of a T1E1.4 compliant ADSL modem and a simpler modem

• US 6,044,107 A
• Filed: 11/13/1996
• Issued: 03/28/2000
• Est. Priority Date: 05/09/1996
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Gatherer, Alan, Shaver, Donald P., Nafie, Mohammed
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): GHAYOUR, MOHAMMAD H
• Application Number:
  US08/748,444
• Time in Patent Office: 1,231 Days
• Field of Search: 375/222, 375/219, 375/202, 370/229, 370/477, 455/450, 455/266
• US Class Current: 375/222
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0016 involving special memory structures, e.g. look-up tables
• CPC Class Codes: H04L 1/0023 characterised by the signalling
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/16 in which the return channel carries supervisory signals, e.g. repetition request signals
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03611 Iterative algorithms
• CPC Class Codes: H04L 25/03 Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 25/4921 using quadrature encoding, e.g. carrierless amplitude-phase coding
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/2649 Demodulators
• CPC Class Codes: H04L 5/1438 Negotiation of transmission parameters prior to communication modified according to link quality H04L1/0001
• CPC Class Codes: H04M 11/06 Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors
• CPC Class Codes: H04M 11/062 using different frequency bands for speech and other data

Abstract

An MDSL modem is provided that is inter-operable with an ADSL modem. The present invention provides a method for modem operation, by dividing available bandwidth for the modem into a plurality of subsets, selecting at least one of the plurality of subsets for use as a communication path, reducing the SNR value used for bit loading for the selected subsets by a predetermined amount, undersampling any received data, and fast fourier transforming the received data to recover the data transmitted. An MDSL modem is provided having circuitry for dividing available bandwidth for the modem into a plurality of subsets, circuitry for selecting at least one of the plurality of subsets for use as a communication path, circuitry for reducing the SNR value used for bit loading for the selected subsets by a predetermined amount, circuitry for undersampling any received data, and circuitry for fast fourier transforming the received data to recover the data transmitted.

Claims

1. A method for modem operation, comprising:

dividing available bandwidth for said modem into a plurality of subsets,

selecting at least one of said plurality of subsets for use as a communication path,

determining the signal-to-noise (SNR) values for said plurality of subsets,

reducing the SNR value used for bit loading for said selected at least one of said plurality of subsets by a predetermined amount,

reducing the SNR value for said subsets that are not selected to a value preventing bit loading for those subsets,

undersampling any data received over the communication path, and

fast Fourier transforming the received data to recover the data transmitted.

2. The method of claim 1 wherein said fast Fourier transforming is sized to functionally correspond to the size of the selected subsets.