PTAB

IPR2020-01404

MediaTek Inc v. Nippon Telegraph Telephone Corp

Log In
Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Wireless Packet Communication Method and Apparatus
  • Brief Description: The ’551 patent discloses a method for simultaneously transmitting wireless packets using multiple channels or Multiple Input Multiple Output (MIMO) technology. The purported novelty is the use of a designated "mandatory channel" that must be idle before any transmission can occur, a feature intended to solve power leakage and interference problems in conventional multi-channel systems.

3. Grounds for Unpatentability

Ground 1: Obviousness over Shpak and Ho - Claims 1, 3, 5, and 7 are obvious over Shpak in view of Ho.

  • Prior Art Relied Upon: Shpak (Application # 2003/0206532) and Ho (Application # 2003/0169769).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Shpak taught a wireless local area network (WLAN) where all access points (APs) use a single "common frequency channel" for all communications, which meets the "mandatory channel" limitation. Ho taught using MIMO to improve data rates in 802.11 systems by splitting data frames for simultaneous transmission over subchannels within a single wireless channel. The combination (Shpak-Ho) allegedly met the preamble's second option: transmitting packets using "a single wireless channel determined to be idle and MIMO."
    • Motivation to Combine: A POSITA would combine Ho's well-known MIMO technique with Shpak's system to achieve increased data rates, a recognized and desirable improvement for 802.11-compliant systems. Petitioner contended this was a predictable application of a known technology to improve a known system.
    • Expectation of Success: Both Shpak and Ho describe techniques compliant with existing 802.11 standards, ensuring their compatibility and making the combination straightforward for a POSITA.

Ground 2: Obviousness over Shpak and Lundby - Claims 1, 3-5, and 7-8 are obvious over Shpak in view of Lundby.

  • Prior Art Relied Upon: Shpak (Application # 2003/0206532) and Lundby (Patent 6,560,292).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground combined Shpak's mandatory "common frequency channel" with Lundby's teaching of dynamically using a secondary channel alongside a primary channel to increase bandwidth when desirable. Shpak's "common frequency channel" served as the primary, mandatory channel, while Lundby provided the teaching to add a secondary channel for simultaneous multi-channel transmission. Petitioner argued this combination met the preamble's first option: transmitting packets using "multiple wireless channels determined to be idle by carrier sense." Lundby's disclosure of transmitting data portions of "equal length" also taught the limitations of dependent claims 3 and 7.
    • Motivation to Combine: A POSITA would have been motivated to enhance the speed of Shpak's WLAN, a stated goal of Shpak, by applying Lundby's technique of adding a secondary channel on an ad hoc basis for data-intensive operations.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success because adding a secondary channel was a known, predictable method to increase throughput in 802.11b systems, which Shpak explicitly noted have multiple channels available from which to choose.

Ground 3: Obviousness over Bugeja and Ho - Claims 1-3 and 5-7 are obvious over Bugeja in view of Ho.

  • Prior Art Relied Upon: Bugeja (Application # 2003/0220112) and Ho (Application # 2003/0169769).

  • Core Argument for this Ground:

    • Prior Art Mapping: Bugeja disclosed a multi-channel AP that assigns a full-power "primary channel" and lesser-powered secondary channels. The primary channel is always assigned to clients in the cell's "outer region," which Petitioner contended functions as a "mandatory channel" for that specific class of devices. Bugeja's system thereby distinguished between "outer-region" clients (STA A), for which a mandatory channel is set, and "inner-region" clients (STA B), which can use other channels, directly mapping to the limitations of claim 2. Combining Bugeja with Ho's MIMO technique satisfied the preamble's options for both single-channel and multi-channel MIMO transmissions.
    • Motivation to Combine: A POSITA would have been motivated to apply Ho's known MIMO technique to Bugeja's multi-channel Single-Input Single-Output (SISO) system to increase the data rate on each channel in a bandwidth-efficient manner.
    • Expectation of Success: Both references are compliant with 802.11 standards, making their combination straightforward and predictable.

  • Additional Grounds: Petitioner asserted claims 4 and 8 are obvious over the Shpak-Ho or Bugeja-Ho combinations in view of Thielecke (Application # 2003/0003863). Thielecke taught selectively adjusting the number of MIMO subchannels used based on channel conditions, a known optimization technique.

4. Key Claim Construction Positions

  • The preamble of claims 1 and 2, which recites transmitting packets "by using multiple wireless channels..., a single wireless channel...and MIMO, or the multiple wireless channels and the MIMO," should be interpreted disjunctively. Petitioner argued the use of "or" means that prior art need only disclose one of the three listed transmission methods to satisfy this limitation, not all three. This interpretation was central to the obviousness grounds, which relied on combinations that satisfy individual options.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued against discretionary denial under 35 U.S.C. §314(a) and the Fintiv factors, stating the petition was filed expeditiously (eight months before the statutory bar) and well before significant investment in the parallel district court litigation. Petitioner asserted that a trial was not imminent, that it would stipulate not to pursue the same invalidity grounds in litigation to avoid overlap, and that the petition’s strong merits favored institution.
  • Petitioner also argued against denial under 35 U.S.C. §325(d), contending that the primary references (Shpak and Bugeja) were not considered during prosecution and are substantively different from the cited art. Specifically, these references disclose a "mandatory channel," the very feature the applicant argued was missing from the prior art to overcome previous rejections.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-8 of Patent 7,280,551 as unpatentable.