PTAB

IPR2018-01556

HTC Corporation v. INVT SPE INC.

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1. Case Identification

2. Patent Overview

  • Title: Communication Terminal Apparatus and Communication Method
  • Brief Description: The ’587 patent describes a communication method in a High Data Rate (HDR) system where a terminal measures downlink channel quality and sends a Data Rate Control (DRC) signal back to a base station. The purported invention is a method of applying unequal error protection (UEP) to this DRC signal, such that signals indicating better channel quality receive stronger error protection, thereby reducing transmission errors for more critical feedback.

3. Grounds for Unpatentability

Ground 1: Claims 1-4 are obvious over Padovani in view of Gils.

  • Prior Art Relied Upon: Padovani (PCT Application No. PCT/US98/23428) and Gils (a 1988 Ph.D. dissertation titled "Design of error-control coding schemes for three problems of noisy information transmission, storage and processing").
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Padovani taught the foundational system: a mobile station in a CDMA system that measures forward link channel quality (C/I) and transmits a corresponding DRC message to a base station. Padovani explicitly recognized the need to encode this DRC message to ensure low error probability for system performance. However, Padovani only disclosed a basic error correcting code. Gils was presented as a seminal reference on UEP coding, teaching how to design error-control schemes that provide stronger protection to more important message positions or entire messages. Petitioner argued that Gils’s detailed tables of optimal Linear Unequal Error Protection (LUEP) codes provided the exact tools to implement the methods claimed in the ’587 patent.
      • For independent claim 1, which requires converting the DRC signal to a codeword whose "code word minimum distance is proportional to the degree of measured downlink channel quality," Petitioner argued a POSITA would apply Gils's coding schemes to Padovani's DRC signal. By selecting different (n,k) coding schemes from Gils’s tables for different DRC values, a set of codewords could be generated where higher DRC values (better channels) correspond to codewords with a greater minimum distance, directly meeting the claim limitation.
      • For independent claim 4, which requires encoding the signal so the "most significant bit... is less susceptible to errors," Petitioner argued Gils's LUEP codes were explicitly designed for this purpose. The separation vectors in Gils's tables define different Hamming distances for each bit in a data word, allowing the most significant bit to be given the greatest protection.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would have been motivated to combine the references to solve a problem explicitly identified in Padovani—the need for robust DRC message encoding. Padovani established that errors in DRC messages negatively impact system throughput. Padovani also taught a non-linear relationship between data rates, meaning an error in a DRC message corresponding to a high-quality channel had a much more significant negative impact than an error for a low-quality channel. Gils provided a known, sophisticated solution (UEP) for the general problem of protecting important data from transmission errors. Therefore, a POSITA would have been motivated to apply the specific UEP techniques from Gils to Padovani's system to more effectively protect the more critical, high-value DRC messages.
    • Expectation of Success: A POSITA would have had a high expectation of success. The combination involved applying known error-correction principles (Gils) to a standard digital communication system (Padovani). Gils provided concrete mathematical tables and constructions, making the implementation predictable and straightforward for an engineer in this field.

4. Key Claim Construction Positions

  • "code word minimum distance" (Claim 1): Petitioner proposed this term be construed as "the minimum number of bits by which a particular code word differs with respect to all other code words." This construction was based on the patent’s own definition and was argued to be the standard meaning in the art.
  • "is proportional to the degree of measured downlink channel quality" (Claim 1): Petitioner proposed this be construed to mean "increases as the downlink channel quality increases at least within a certain range." This construction was crucial because it did not require a strict linear proportion, accommodating the step-wise increases in error protection shown in the patent's examples and in the prior art coding schemes from Gils. This broader interpretation allowed Petitioner to map Gils's tables of discrete coding schemes to the claim language.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-4 of the ’587 patent as unpatentable.