PTAB

IPR2017-01200

Ericsson Inc v. Regents Of University Of Minnesota

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Codes with Alternating Constraint Lengths
  • Brief Description: The ’185 patent discloses methods and systems for error correction coding in digital communications. The technology focuses on using Irregular Repeat-Accumulate (IRA) codes, a type of Low-Density Parity-Check (LDPC) code, where parity bits are generated and then selectively removed ("punctured") according to specific patterns to achieve a desired code rate before transmission.

3. Grounds for Unpatentability

Ground 1: Obviousness over Divsalar and Richardson - Claims 1, 2, 4–6, 8, 9, 11–13, and 15–18 are obvious over Divsalar in view of Richardson.

  • Prior Art Relied Upon: Divsalar (Patent 7,020,847) and Richardson (Patent 7,237,185).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Divsalar disclosed all key limitations of independent claims 1, 8, and 15, including a method for generating parity bits using an IRA code structure. Divsalar explicitly taught encoding information bits, repeating some of those bits, interleaving them, and then accumulating them to generate parity bits. Petitioner contended that Divsalar also disclosed puncturing these parity bits to achieve a target code rate, thus teaching the "selecting a puncturing pattern" limitation. Richardson, a foundational reference on LDPC codes, was cited as providing the broader context and motivation for these techniques. It described general principles of designing LDPC codes, including puncturing parity bits and information bits, reinforcing the knowledge of a person of ordinary skill in the art (POSITA).
    • Motivation to Combine: Petitioner asserted a POSITA would combine Divsalar and Richardson because both addressed the same problem: designing efficient and powerful error correction codes for communication systems. Richardson provided the well-known theoretical framework and general design choices for LDPC codes, while Divsalar provided a specific, high-performance IRA code implementation. A POSITA seeking to optimize or implement the IRA code in Divsalar would have naturally consulted a foundational text like Richardson for guidance on techniques like puncturing, which Richardson taught was a conventional method for rate matching.
    • Expectation of Success: A POSITA would have a high expectation of success because combining the teachings was merely the application of a known technique (puncturing, as detailed in Richardson) to a known system (the IRA coder of Divsalar) to achieve a predictable result (rate compatibility). The underlying principles of channel coding were well-understood, and the effects of puncturing were predictable.

Ground 2: Obviousness over Divsalar, Richardson, and 3GPP - Claims 3, 7, 10, and 14 are obvious over Divsalar, Richardson, and 3GPP.

  • Prior Art Relied Upon: Divsalar (Patent 7,020,847), Richardson (Patent 7,237,185), and 3GPP (3GPP TR 25.892 V6.0.0).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground built upon Ground 1 to address dependent claims requiring the puncturing pattern to be based on a "family of pre-determined puncturing patterns." Petitioner argued that Divsalar and Richardson established the base combination, while 3GPP explicitly disclosed the missing limitation. The 3GPP technical specification, which defined standards for 3G wireless communication, taught using a set of pre-defined puncturing patterns for rate matching in turbo coders. The specification provided tables of these patterns, which were selected based on the number of bits to be punctured.
    • Motivation to Combine: Petitioner argued a POSITA would be motivated to incorporate the teachings of 3GPP into the Divsalar/Richardson framework to create a practical, standardized system. The 3GPP standard directly addressed the problem of rate matching for different data block sizes and channel conditions, a known issue in wireless system design. A POSITA implementing the advanced IRA codes from Divsalar would look to established industry standards like 3GPP for proven methods of handling rate matching, such as using families of pre-determined puncturing patterns. This combination represented a straightforward adoption of a standard industry practice to enhance the Divsalar system.
    • Expectation of Success: Success was expected because applying standardized puncturing algorithms (from 3GPP) to a channel coder (like Divsalar's) was a routine and well-established practice in the field of wireless communications. The behavior of such systems was predictable.

  • Additional Grounds: Petitioner asserted additional obviousness challenges based on Jin (Patent 7,853,880) in view of Richardson, as well as Jin in view of Richardson and 3GPP. These grounds relied on similar arguments, substituting Jin for Divsalar as the primary reference disclosing an IRA coding structure.

4. Key Claim Construction Positions

  • "based on a selected puncturing pattern": Petitioner argued this term should be construed to mean "according to a chosen puncturing pattern." Petitioner contended the Patent Owner attempted to narrow the term during prosecution to require that the pattern be selected from a plurality of patterns, but argued this limitation was not supported by the claim language itself, which only required a single "selected" pattern. This construction was critical to Petitioner's argument that primary references like Divsalar, which disclosed a single puncturing scheme, met the limitation of the independent claims.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-18 of the ’185 patent as unpatentable.