LG Electronics Inc v. Pantech Wireless LLC

1. Case Identification

• Case #: IPR2023-01270
• Patent #: 10,869,247
• Filed: August 11, 2023
• Petitioner(s): LG Electronics Inc.
• Patent Owner(s): Pantech Wireless, LLC
• Challenged Claims: 1-20

2. Patent Overview

• Title: Wireless Transmit/Receive Unit (WTRU) and Method for Prioritizing Retransmissions
• Brief Description: The ’247 patent describes an error-control technique for wireless communications. The invention allows a wireless device to determine whether to retransmit a data block to a base station based on received uplink scheduling information, rather than being based on the receipt of an explicit negative acknowledgement (NACK) signal.

3. Grounds for Unpatentability

Ground 1: Obviousness over Lucent - Claims 1-2, 8, 11-12, and 18 are obvious over Lucent.

• Prior Art Relied Upon: Lucent (R1-03-0285, "Signalling for H-ARQ Operation," a 3GPP proposal).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Lucent, a proposal for scheduling uplink transmissions in an asynchronous Hybrid Automatic Repeat Request (H-ARQ) operation, teaches all limitations of the independent claims. Lucent disclosed a User Equipment (UE) that determines retransmission based on a "schedule grant message" from a base station ("Node-B"). This message contains a "New Data Indicator" (NDI) bit. If the NDI value has not changed from the previous transmission for a given H-ARQ process, it implicitly signals a NACK, and the UE retransmits the last packet. This, Petitioner asserted, meets the core claim limitation of determining retransmission based on scheduling information and not on receiving an explicit NACK. Lucent also disclosed including an "H-ARQ channel" identifier in the message, which Petitioner mapped to the claimed "H-ARQ process identification."
  • Motivation to Combine (for §103 grounds): This ground was presented primarily as anticipation under 35 U.S.C. §102, but in the alternative as obviousness under §103. Petitioner argued it would have been obvious to implement Lucent's system using a standard processor and transceiver, as these were well-known components for performing such functions in a UE.
  • Expectation of Success (for §103 grounds): A person of ordinary skill in the art (POSITA) would have had a high expectation of success in implementing Lucent's teachings, as it described a complete and logical system for managing H-ARQ retransmissions.

Ground 2: Obviousness over Lucent in view of Liu - Claims 1-2, 8, 11-12, and 18 are obvious over Lucent in view of Liu.

• Prior Art Relied Upon: Lucent and Liu (Application # 2005/0048920).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground built upon the disclosures of Lucent. To the extent the Board might find Lucent's "H-ARQ channel" identifier does not explicitly meet the "H-ARQ process identification" limitation, Petitioner argued that Liu supplied this teaching. Liu disclosed a "downlink control channel" for scheduling that explicitly includes a "HARQ ID" field to "identify a specific process in a hybrid automatic repeat request (HARQ) process."
  • Motivation to Combine (for §103 grounds): A POSITA would combine Lucent and Liu to improve the precision of Lucent's system. If a single H-ARQ channel in Lucent could run multiple parallel H-ARQ processes, adding Liu's explicit "HARQ ID" to the schedule grant message would allow the base station to unambiguously identify which specific process requires retransmission. This modification was presented as a straightforward way to improve the accuracy and efficiency of uplink retransmissions in a known system.
  • Expectation of Success (for §103 grounds): Success was reasonably expected because adding an identification field to a control message was a well-known technique in the art for managing communication processes.

Ground 3: Obviousness over Kuchibhotla in view of Liu - Claims 1-7 and 11-17 are obvious over Kuchibhotla in view of Liu.

• Prior Art Relied Upon: Kuchibhotla (Application # 2004/0223507) and Liu.

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner presented this as an alternative to the Lucent-based grounds. Kuchibhotla disclosed an improved H-ARQ system that uses a "new data expected" (NDE) indicator in a scheduling assignment message (SAM) to enhance reliability, as ACK/NACK signals could be lost or misread. The mobile station (MS) determines whether to retransmit based on the NDE value in the SAM, and explicitly ignores a conflicting ACK/NACK signal. This directly taught determining retransmission based on scheduling information and not a NACK. However, Kuchibhotla did not specify how the MS ascertains which prior data packet a given SAM corresponds to in an asynchronous system. Liu, as in Ground 2, taught including a "HARQ ID" in scheduling information to identify the specific H-ARQ process.
  • Motivation to Combine (for §103 grounds): A POSITA would combine Kuchibhotla and Liu to solve a problem inherent in Kuchibhotla's asynchronous H-ARQ system. The unpredictable timing of SAMs in Kuchibhotla could cause the MS to misidentify which prior transmission a SAM relates to. A POSITA would have been motivated to add Liu's explicit "HARQ ID" to Kuchibhotla's SAM to enable the MS to accurately pinpoint which data needs retransmission, thereby avoiding retransmitting the wrong packet.
  • Expectation of Success (for §103 grounds): A POSITA would have reasonably expected success, as incorporating a process identifier into a scheduling message was a known solution for disambiguating communications in wireless systems.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including combinations with Das (Application # 2003/0076783) to teach using a different Modulation and Coding Scheme (MCS) for a retransmission than for the original transmission (for claims 9-10, 19-20). Further grounds added Rathonyi (Patent 6,359,877) to explicitly teach the use of a standard "transceiver" and "processor" for all foregoing combinations.

4. Key Claim Construction Positions

• Petitioner argued that claim terms should be given their plain and ordinary meaning. It contended that even if the limitation "determine whether to retransmit...not based on whether the WTRU has received a NACK" were construed as a means-plus-function term, the prior art still disclosed the corresponding structure (a processor implementing an algorithm) and its equivalents.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §325(d) was inappropriate because the prior art and arguments were not the same or substantially the same as those considered during prosecution. It noted that the ’247 patent issued from an application that received a first-action allowance with no substantive prosecution history.
• Petitioner also argued against discretionary denial under Fintiv factors, stating that the co-pending district court litigation was in its very early stages, with discovery just beginning. Petitioner asserted its intent to seek a stay of the litigation if the IPR is instituted and that the median time to trial suggests the Board's final written decision (FWD) would issue before trial commences.