Nortel Networks Corporation

Gin Liu

Michael A Campbell

Gary T Stone

Leslie Derek Humphrey

Gwendolyn Kate Harris

Michel M Darveau

Anthony Peter Peck

Mohammed Reza Pakravan

Liqian Yao

Mike M J Wingrove

Nelson M Lee

Johnny Fung

Andrew Dempster

Alfred Haw

Kim B Crawford

Method and apparatus for retrieving the channel frequency response H(f), the noise N(f), measured at initialization and the signal to noise ratio SNR(f) measured at show time on a per bin basis, in the upstream or downstream direction. Initialization H(f) is used for analyzing the physical copper loop condition between tip and ring. Initialization N(f) is used for analyzing the crosstalk. Showtime SNR(f) is used for analyzing time dependent changes in crosstalk levels and line attenuation. The combination of H(f), N(f) and SNR(f) allows analysis of the line conditions for reaching the maximum data rate of a given loop, scheduling maintenance and plant update.

Method and apparatus for monitoring channel frequency response

Achieved bandwidths for existing subscribers are collected and organized into a statistical bandwidth table utilizing characterizing information, such as the Central Office (CO) that provided the service, the type of xDSL service that was provided, the primary, secondary, and other cable segments over which service was provided, and the subscriber loop length increment. To estimate anticipated bandwidth for a new subscriber, the new subscriber's characterizing information is obtained and used to select one or more entries from the statistical bandwidth table of statistical actual bandwidths achieved by other users that most closely matches the new subscriber's characterizing information. The statistical bandwidth information for the other similarly situated subscribers is used as an estimate bandwidth information for the new subscriber.

Method and apparatus for statistical prediction of access bandwidth on an xDSL network

A DSL splitter providing test access to an interconnected subscriber loop and method are disclosed. The DSL splitter in a first test mode, provides access to allow testing of an interconnected subscriber loop by way of a DSL input. A disconnect in series with an associated low pass filter (LPF) disconnects POTS input. Such a splitter may similarly provide access to allow testing of the subscriber loop by way of the POTS input in a second test mode. In this second test mode, a by-pass by-passes the LPF, and a disconnect may disconnect an associated high pass filter (HPF) and DSL input. Preferably, the splitter only assumes its test modes after receipt of authorization from the other provider. The splitter may be controllable by way of a control circuit having an access port used to receive commands to have the splitter assume its normal, or first or second test mode. The splitter may assume its normal operating mode from a test mode, after expiry of a timeout timer.

DSL splitter providing test access to an interconnected subscriber loop and method

To identify interference from other data carrying subscriber loops (i.e., from loop disturbers), a power spectral density sample may be obtained from the subscriber loop under consideration based on at least one measurement while the loop is not transmitting data. The sample power spectral density may then be correlated with each one of a set of known power spectral densities. Each known power spectral density represents a power spectral density in a loop which is not transmitting data in the presence of one of (i) no subscriber loop disturbers, (ii) a particular subscriber loop disturber, and (iii) particular subscriber loop disturbers. Based on the correlations, subscriber loop disturbers may be recognized.

Method for performing subscriber loop disturber recognition by comparing measured sample power spectral densities with a set of known power spectral densities

A method and apparatus for single-ended qualification of subscriber loops for xDSL services is described. The method involves first screening a subscriber loop database record for disqualifying devices or services on the subscriber loop. If none are found, a set of predetermined electrical characteristics of the subscriber loop are derived from information in the database, or directly measured using test equipment at a central office end of the subscriber loop. The electrical characteristics are used to compute an available bandwidth on the subscriber loop for xDSL services. The advantage is the rapid and inexpensive qualification of subscriber loops which reduces response time to potential customer queries and facilitates deployment of xDSL services.

Single-ended subscriber loop qualification for xDSL service

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Brampton, Canada

Gin Liu