Adaptive margin and band control in DSL system

Abstract

Controlling margins in a DSL modem pair is based on collected operational data. The operational data is analyzed and at least one of the modems in the modem pair is instructed to use a margin-related parameter value to assist the modem pair in meeting a margin target, such as a margin limit imposed by a DSL standard or the like. A controller, such as a DSM Center, a 'smart' modem unit and / or a computer system can collect and analyze the operational data and generate one or more margin-related parameter values. The margin-related parameter value may be a PSD-related value, such as the MAXNOMPSD, MAXNOMATP or PSDMASK parameter used by various ADSL systems, and may be a shaped spectral mask and / or caps or limits on bit loading for use in transmissions between the modems. In some cases, preference bands can be imposed to direct modems to favor and / or avoid certain frequencies in the modem's usable band(s). The operational data may include historical data relating to prior performance of the modem pair and prior margin compliance. A distribution of margins also may be based on operational data and may be estimated as a function of data rate. Using the estimated margin distribution, a distribution of performance parameters also is calculated, including the probabilities of line outages and probabilities of one or more error parameters exceeding minimum levels. Data rates and / or performance-related parameters may be set on the basis of the estimated performance of the system using various margin settings and levels.

Description

technical field [0001] The present invention generally relates to methods, systems and apparatus for managing digital communication systems. More specifically, the present invention relates to adaptive control of various transmission parameters including, but not limited to, maximum transmit power spectral density, maximum aggregate transmit power, transmit frequency band preference, minimum and maximum receive margin, frequency-dependent bitloading and power control and / or bitloading limitations. Background technique [0002] Digital Subscriber Line (DSL) technology provides the wide bandwidth possible for digital communications over existing telephone subscriber lines (called loop and / or copper wire equipment). Telephone subscriber lines can provide this bandwidth even though they were originally designed only for voice-band analog communications. In particular, asymmetric DSL (ADSL) can tune the characteristics of subscriber lines by using discrete multi-tone (DMT) line...

AI Technical Summary

Problems solved by technology

[0011] (2) Limit the maximum gain reduction request to 14.5dB for ATU-R (downlink receiver) and ATU-C (uplink receiver), which is usually not enough to achieve the intent of MAXSNRM

[0014] (5) Some manufacturers' ATU-R receivers completely ignore MAXSNRM and never request a power reduction of 14.5dB even though such a power reduction is commanded by the operator or the standard

[0015] (6) Gain swaps during actual operation may be limited (recommended but not required in Annex A) to allow only ±2.5dB gain adjustments after training in SHOWTIME

[0021] (5) ATU-R receivers from some manufacturers still completely ignore power compensation (back off), and unfortunately it is not tested even in the latest test procedure of the DSL forum called WT-85 ( Although there is a test, almost all pass it, and there is no verification in the test observing MAXSNRM)

Due to the fact that modems and other equipment may or may not actually be compliant with the appropriate standards, and, or more importantly, due to the fact that user-adjacent lines may or may not be used in compliance with standard equipment and practices, many users suffer from adverse or less than best service

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