PTAB

IPR2020-01099

Cradlepoint Inc v. Sisvel Intl SA

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Data Transmission in Radio System
  • Brief Description: The ’561 patent relates to a method and apparatus for data transmission in a radio system, such as an Enhanced General Packet Radio Service (EGPRS) system, that uses incremental redundancy. The technology involves applying a first puncturing pattern for an original data transmission and a different, second puncturing pattern for a retransmission, thereby creating different code rates and allowing the data blocks to be efficiently combined at the receiver.

3. Grounds for Unpatentability

Ground 1: Claims 1-3, 5-7, 9, and 10 are anticipated under 35 U.S.C. §102 or obvious under 35 U.S.C. §103 over [Chen](https://ai-lab.exparte.com/case/ptab/IPR2020-01099/doc/1003).

  • Prior Art Relied Upon: Chen (International Publication No. WO 99/26371).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Chen discloses every element of the challenged claims. Chen teaches a method for "time efficient retransmission using symbol accumulation" which involves transmitting a data block using convolutional coding and puncturing. Upon detecting an error (e.g., via a CRC check), a retransmission is requested. Petitioner contended that Chen’s "alternative embodiment" explicitly teaches the core concept of the ’561 patent: puncturing a retransmitted packet differently than the original transmission. Specifically, Chen describes an initial transmission at a 1/2 code rate (puncturing two of four coded symbol streams) and a retransmission containing only symbols from one of the previously punctured streams, resulting in an increased code rate of 1/1 for the retransmission. Chen also teaches accumulating (combining) symbols from the original and retransmitted packets for decoding.
    • Motivation to Combine (for §103): For the alternative obviousness argument, Petitioner asserted that a person of ordinary skill in the art (POSITA) would have found it obvious to apply Chen's teachings, as modifying code rates using different puncturing patterns was a well-known technique for balancing throughput and error correction.

Ground 2: Claims 1-10 are obvious over Chen in view of [Eriksson](https://ai-lab.exparte.com/case/ptab/IPR2020-01099/doc/1004).

  • Prior Art Relied Upon: Chen (WO 99/26371) and Eriksson (a 1999 IEEE conference paper).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that to the extent Chen was found not to teach every limitation, Eriksson supplies the missing elements. Eriksson compares link adaptation and incremental redundancy for EGPRS systems and proposes combining them. It teaches using Modulation and Coding Schemes (MCSs) organized into "families" where different MCSs within a family use different puncturing patterns to achieve different, but compatible, code rates. Eriksson explicitly teaches that a retransmission can be sent using a different MCS from the same family as the original transmission, which would necessarily change the code rate. This provides a specific, standardized implementation of the general concept in Chen.
    • Motivation to Combine: A POSITA would combine Chen and Eriksson as they address the same technical problem of optimizing data retransmission in cellular systems. A POSITA would look to a research paper like Eriksson, which analyzes performance trade-offs in the emerging EGPRS standard, to find concrete methods for implementing the adaptive retransmission strategy described more generally in Chen. The goal in both references is to improve efficiency by adapting to channel conditions.
    • Expectation of Success: A POSITA would have a high expectation of success in applying Eriksson's MCS-switching strategy to a system like Chen's. Eriksson provides a clear framework with defined code rates and families, demonstrating a predictable way to achieve more granular control over retransmission data rates.

Ground 3: Claims 1-10 are obvious over Chen in view of [GSM 03.64](https://ai-lab.exparte.com/case/ptab/IPR2020-01099/doc/1005).

  • Prior Art Relied Upon: Chen (WO 99/26371) and GSM 03.64 (an ETSI technical standard).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted a similar combination theory as with Eriksson, but with the GSM 03.64 standard. The GSM 03.64 standard, which defines EGPRS, mandates a type-II Hybrid ARQ (HARQ) scheme that relies on incremental redundancy. The standard explicitly states that for retransmissions, "the same or another MCS from the same family of MCSs can be selected." The standard's tables define the different code rates for each MCS within a family. This directly teaches changing the code rate for retransmissions by selecting a different MCS, which inherently uses a different puncturing scheme. Petitioner also argued that GSM 03.64 and the related GSM 04.60 standard teach the specific MCS combinations recited in dependent claims 4 and 8.
    • Motivation to Combine: A POSITA would be strongly motivated to implement the concepts from Chen in a manner compliant with the predominant industry standard, GSM 03.64. The standard provided the official, required blueprint for building interoperable EGPRS devices, making it a natural source for a POSITA to consult when designing a system for that environment.
    • Expectation of Success: Success would be highly expected, as implementing a known technique (from Chen) according to a detailed technical standard (GSM 03.64) is a routine design task for a POSITA. The standard is specifically designed to ensure that such combinations of techniques work predictably.

4. Key Claim Construction Positions

  • Petitioner argued that six "means for..." limitations in claims 5, 9, and 10 are means-plus-function limitations under pre-AIA §112 ¶ 6. For each, Petitioner identified the claimed function and the corresponding structure from the ’561 patent's specification (e.g., "transmission means" corresponds to a modulator, filters, and amplifiers, and "means for combining" corresponds to software for symbol combination executed on a processor).
  • Petitioner proposed construing the term "code rate" as "the ratio of the number of user data bits to the coded data bits of a channel," based on the patent's explicit definition. This construction was central to arguments that the prior art discloses increasing this ratio for retransmissions.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-10 of Patent 6,529,561 as unpatentable.