PTAB

IPR2022-00911

MediaTek Inc v. NXP USA Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Multi-User Transmission Procedure
  • Brief Description: The ’874 patent discloses methods for an access point in a wireless local area network to coordinate simultaneous uplink transmissions from multiple client stations. The system uses a "trigger frame" containing a common information field with parameters for all stations and per-station information fields with parameters specific to individual stations.

3. Grounds for Unpatentability

Ground 1: Claims 1-3, 5, 10-12, 14, 19, and 20 are obvious over Chun in view of Grandhi.

  • Prior Art Relied Upon: Chun (Patent 10,278,172) and Grandhi (Application # 2006/0248429).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Chun disclosed the core invention: an access point generating a trigger frame with a MAC frame body containing both a "common control information" field and a "non-common control information" (per-station) field. Chun’s common field taught including bandwidth and guard interval (GI) information, while its per-station field taught including frequency resource allocation. The primary missing element was an explicit disclosure of including a long training field (LTF) mode in the common information field. Grandhi allegedly supplied this, teaching a request frame (a type of trigger frame) whose MAC frame body includes a field for the "type of HT-long training fields (LTFs)."
    • Motivation to Combine: Petitioner contended that a person of ordinary skill in the art (POSITA) would have been motivated to combine these references because both sought to improve the efficiency of multi-user data transmission in IEEE 802.11 WLAN protocols. A POSITA would incorporate Grandhi's teaching for signaling the LTF mode into Chun’s common information field to efficiently align transmissions for all stations, thereby improving responsiveness and avoiding redundant signaling in per-station fields.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success because the combination involved a straightforward software-level change—setting bits in a subfield of a MAC frame body—a known technique used to improve a similar system.

Ground 2: Claims 4, 6-9, 13, and 15-18 are obvious over Chun in view of Grandhi and Ghosh.

  • Prior Art Relied Upon: Chun (Patent 10,278,172), Grandhi (Application # 2006/0248429), and Ghosh (Application # 2013/0301551).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the Chun/Grandhi combination by adding Ghosh to teach limitations related to transmit power and broadcast/unicast frames. Petitioner asserted that while Chun recognized the need for power adjustment among stations, Ghosh explicitly taught including a "transmit power" field within a "User Specific Profile" of its trigger frame. Ghosh also expressly taught that its trigger frame could be sent as a broadcast to multiple stations or as a unicast transmission to individual stations, satisfying the limitations of claims 6-9.
    • Motivation to Combine: A POSITA, aware of the power difference problem identified in Chun, would look to solutions like Ghosh to implement station-specific power control efficiently. Incorporating Ghosh's transmit power field into Chun's per-station field was argued to be an obvious design choice. Furthermore, using broadcast or unicast transmissions was a known design trade-off between channel efficiency and power efficiency, and Ghosh provided an express teaching for implementing these known options in a trigger frame context.
    • Expectation of Success: The combination had a high expectation of success because it involved implementing a known solution (per-station power control) for a known problem (power differences) via a simple software change.

Ground 3: Claims 1-20 are obvious over Abraham in view of Grandhi, Ghosh, and Merlin.

  • Prior Art Relied Upon: Abraham (Application # 2010/0329195), Grandhi (Application # 2006/0248429), Ghosh (Application # 2013/0301551), and Merlin (Application # 2015/0063257).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground used Abraham as the primary reference, which disclosed a "control message" (trigger frame) with a structure containing a "Common Information" portion and a "Per STA Info" portion. Petitioner argued the secondary references provided the specific transmission parameters to populate Abraham's framework. Grandhi taught including an LTF mode (common). Ghosh taught including bandwidth and GI information (common) and transmit power (per-station). Merlin taught including frequency/tone allocation in a per-station "STA Info" field. Together, this combination allegedly disclosed every parameter recited in the challenged claims.
    • Motivation to Combine: Petitioner argued all four references related to improving the IEEE 802.11 protocol for uplink multi-user transmission. A POSITA starting with Abraham's basic trigger frame structure would have been motivated to consult other references like Grandhi, Ghosh, and Merlin to incorporate well-known and necessary transmission parameters to create a functional and efficient system. The combination was presented as a straightforward aggregation of known elements to achieve a predictable result.
    • Expectation of Success: A POSITA would expect success, as the combination merely involved implementing known transmission parameters into a known trigger frame structure. No new hardware was required, and the integration was a predictable software-level change.

4. Key Claim Construction Positions

  • Petitioner addressed the term "a long training field (LTF) mode," which appears in the claims but not the specification.
    • Petitioner proposed the construction: "a way or manner in which a long training field is expressed."
    • Petitioner noted that Patent Owner had previously proposed the plain and ordinary meaning.
    • Petitioner argued the claims are obvious under either construction, so the Board did not need to resolve the dispute.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-20 of Patent 10,764,874 as unpatentable under 35 U.S.C. §103.