DSL System Claim that Recites an Algorithm Beats 101

Ex parte Patrick Duvaut and Massimo Sorbara
Decided: April 28, 2009

My apologies for the delay in posting on this decision. My thanks go out to Aaron R. Fiegelson of the 12:01 Tuesday Blog for getting this decision out the day it was available.


At the outset, it is important to note that the claims at issue in this decision are system claims.

Claim 1 is representative:
Based on this, it's clear the board was dealing with a "system" that implements some mathematical function. More specifically, the claimed DSL system is "configured to" provide to provide the claimed power spectral density mask.

The Examiner rejected the claims under 101. The Examiner reasoned that claims 1-28 recite nothing more than a non-statutory mathematical algorithm or equation of a DSL communications system that has no practical application.

In first finding the claim was actual a system claim, the Board found the preamble limiting. Next, they relied on the specification to determine that a DSL system includes: (1) a remote ADSL Terminating Unit (ATU-R) in bi-directional DMT communication with the a central office ADSL Terminating Unit (ATU-C) or (2) a central office High Speed ADSL Terminating Unit (HSTU-C) in bi-directional DMT communication with a remote High Speed DSL Terminating Unit (HSTU-R).

Using this, the Board found that the claim was a system claim and thus within one of the four statutory categories.

Next, the Board reminded us that the mathematical algorithm exception to § 101 applies to true apparatus claims by citing Alappat. In reversing the Examiner's 101 rejection, the panel reasoned that:

The recited communications system is a particular machine that transmits data on a digital subscriber line. The claimed machine is, therefore, tailored to DSL applications. Moreover, the recited DSL communications system is programmed or configured to provide a PSD mask for spectral shaping a DBM mode downstream transmission defined by a specific equation. Thus, the recited DSL communication system is not a general purpose computer but a particular or special purpose machine.

In the end, it appears that the panel was convinced that claim 1 did not pre-exempt “the use of any apparatus employing the combination of mathematical calculations recited.” Said another way, it appears that the Board was impressed with the fact that claimed PSD could be used in other communications systems and applications. It appears that Board took the view that claims at issue only cover DSL systems.