PTAB

IPR2022-00912

MediaTek Inc v. NXP USA Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Method and Apparatus for Processing Data Units in a Wireless Communication System
  • Brief Description: The ’018 patent discloses methods for generating and processing data units in a wireless local area network (WLAN) to allow a receiving device to determine if it is an intended recipient. The technology involves using various fields within a data unit’s preamble to distinguish between single-user and multi-user transmission modes and to convey receiver-specific information for purposes of power management and data processing.

3. Grounds for Unpatentability

Ground 1: Obviousness over Fischer and Liu - Claims 1-21 are obvious over Fischer in view of Liu.

  • Prior Art Relied Upon: Fischer (Application # 2010/0309834) and Liu (Application # 2005/0025080).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Fischer teaches a multi-user, multiple-input, multiple-output (MU-MIMO) wireless communication system consistent with the IEEE 802.11ac standard. Fischer discloses generating data units that include a preamble with training sequences and various signaling fields. Specifically, Fischer’s Very High Throughput Signal (VHT-SIG) field contains an indicator bit to designate single-user (SU) or multi-user (MU) transmission modes, as well as fields that specify the number of spatial streams for each user. Petitioner asserted that Fischer explicitly teaches that in SU mode, bit-fields corresponding to other potential users (e.g., Nsts2-Nsts4) are unused and available for "other usage." However, Fischer does not specify using these available bits to include a receiver identifier.
    • Motivation to Combine: Liu was cited to remedy this gap, as it expressly teaches a method for saving power in a wireless network by inserting a partial destination MAC address (a receiver identifier) into otherwise unused bits of a frame’s physical layer header. According to Liu, when a receiving station determines that its MAC address does not match the partial address in the header, it can immediately cease decoding the rest of the frame, thereby conserving significant processing power and battery life. Petitioner argued a person of ordinary skill in the art (POSITA) would combine Liu’s well-known power-saving technique with Fischer’s system because improving power efficiency is a primary and constant objective in wireless device design, and Fischer explicitly provides unused bits available for just such an "other usage."
    • Expectation of Success: A POSITA would have had a high expectation of success in this combination. Both references operate within the context of standard WLAN packet structures, and applying Liu’s partial address filtering to the unused bits in Fischer’s VHT-SIG field represented a predictable implementation of a known solution to the pervasive problem of power consumption.

Ground 2: Obviousness over Fischer and Lee - Claims 1-21 are obvious over Fischer in view of Lee.

  • Prior Art Relied Upon: Fischer (Application # 2010/0309834) and Lee (Application # 2012/0044925).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground relies on Fischer for the same foundational teachings as Ground 1, establishing a MU-MIMO system with a VHT-SIG field that contains unused bits during SU mode transmissions. The argument asserted that Lee, similar to Liu, provides the key teaching of utilizing these bits for receiver identification to achieve power savings. Lee specifically teaches inserting a partial Association Identifier (AID)—another form of receiver identifier—into the VHT-SIG portion of a data unit.
    • Motivation to Combine: The motivation is analogous to that in Ground 1. Lee discloses that including a partial AID allows unintended recipient stations to recognize they are not the target and switch to a power-saving sleep mode much earlier, without having to process subsequent fields. A POSITA would have been motivated to incorporate Lee’s technique into Fischer's system to gain these well-understood power-saving benefits. The combination was presented as an obvious design choice, applying a known efficiency-improving technique to the framework provided by Fischer.
    • Expectation of Success: Petitioner argued success would have been highly probable, as Lee’s method is designed for the same type of Physical Layer Convergence Procedure (PLCP) frame structure that is disclosed in Fischer. The combination represented a straightforward application of one known technique (partial AID filtering for power saving) to another known system (Fischer's packet structure with available bits).

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under 35 U.S.C. §325(d) would be inappropriate because the asserted grounds are materially different from the art and arguments considered by the USPTO Examiner during the original prosecution. The petition asserted that the primary reference, Fischer, was only cited in an Information Disclosure Statement (IDS) and was not substantively analyzed or applied by the Examiner in any rejection. Furthermore, the secondary references were either used in a limited capacity for dependent claims that ultimately became moot (Liu) or were not cited at all during prosecution (Lee). Therefore, Petitioner contended that the core prior art combinations and the specific obviousness theories presented in the petition were never before the Examiner for consideration.

5. Relief Requested

  • Petitioner requests the institution of an inter partes review and the cancellation of claims 1-21 of the ’018 patent as unpatentable under 35 U.S.C. §103.