Ericsson Inc. v. Uniloc 2017 LLC

1. Case Identification

• Case #: IPR2020-00420
• Patent #: 6,868,079
• Filed: January 17, 2020
• Petitioner(s): Ericsson Inc.
• Patent Owner(s): UNILOC 2017 LLC
• Challenged Claims: 1-5, 7, and 17

2. Patent Overview

• Title: Radio Communication System with Request Re-transmission Until Acknowledged
• Brief Description: The ’079 patent discloses a radio communication system where a secondary station (e.g., a mobile station) repeatedly transmits a request for service in successively allocated time slots to a primary station (e.g., a base station) until an acknowledgement is received. The primary station determines whether a request was transmitted by examining received signals from the secondary station across multiple time slots.

3. Grounds for Unpatentability

Ground 1: Claims 1, 5, 7, and 17 are obvious over Merakos, Kay, and Alamouti.

• Prior Art Relied Upon: Merakos (Patent 5,521,925), Kay (Patent 5,299,198), and Alamouti (Patent 5,933,421).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Merakos teaches a TDMA system where mobile stations send allocation requests (RARs) in pre-assigned control subslots. Kay, which is incorporated by reference into Merakos, teaches improving reliability by repeatedly transmitting a request message (time diversity) without waiting for an acknowledgement to mitigate signal fading. This combination taught all elements of independent claims 1 and 17 except for the primary station’s method of detection. Alamouti supplied this final element by teaching various diversity reception techniques for processing multiple received copies of a signal, including combining the signals (e.g., maximal ratio combining) to improve the signal-to-noise ratio or scanning the signals until one is found to exceed a threshold.
  • Motivation to Combine: A POSITA would combine Merakos and Kay because Kay is explicitly incorporated by reference and addresses the known problem of signal fading in wireless systems. A POSITA implementing the time diversity transmission of Merakos-Kay would then turn to a reference like Alamouti for known, compatible techniques to receive and process those multiple transmissions, thereby improving reception quality and system reliability.
  • Expectation of Success: The combination involved applying known solutions (time diversity transmission and reception) to solve a known problem (fading) in a predictable manner. The techniques were standard in the field and complementary, ensuring a high expectation of success in improving the robustness of the Merakos system.

Ground 2: Claims 3 and 4 are obvious over Merakos, Kay, Alamouti, and Dent.

• Prior Art Relied Upon: Merakos (Patent 5,521,925), Kay (Patent 5,299,198), Alamouti (Patent 5,933,421), and Dent (Patent 5,430,760).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground built upon the Merakos-Kay-Alamouti combination and added Dent to teach the power modification limitations of dependent claims 3 and 4. Petitioner asserted that Dent addressed the problem of interference by teaching a method where an initial access request is transmitted at a low power level, with subsequent retransmissions sent at increased power levels until the message is detected by the base station. This directly taught modifying the power of re-transmitted requests in response to a lack of acknowledgement (claim 3) and specifically increasing that power (claim 4).
  • Motivation to Combine: A POSITA designing the system of Merakos-Kay-Alamouti would be concerned with managing interference, a fundamental issue in cellular networks. Dent provided a well-known and directly applicable technique for power control to minimize interference from access requests. A POSITA would therefore combine Dent's power-ramping scheme with the base combination to create a more efficient and less-interfering system.
  • Expectation of Success: Since all references involved TDMA cellular systems and addressed common problems like interference, a POSITA would expect that integrating Dent's established power control method would predictably reduce interference without disrupting the system's primary function.

Ground 3: Claim 2 is obvious over Merakos, Kay, Alamouti, and Ling.

• Prior Art Relied Upon: Merakos (Patent 5,521,925), Kay (Patent 5,299,198), Alamouti (Patent 5,933,421), and Ling (Patent 6,172,970).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground added Ling to the base combination to teach the specific thresholding logic of dependent claim 2. Petitioner argued that claim 2 requires the primary station to determine a request has been transmitted only if the level of a received request is between lower and upper thresholds. Ling taught an adaptive diversity receiver that used combining diversity (e.g., equal-gain combining) only when received signal qualities were below an upper threshold (too weak for simple selection) but above a lower threshold (strong enough for demodulation). This directly mapped to the claimed limitation.
  • Motivation to Combine: A POSITA would incorporate Ling's threshold-based adaptive reception into the Merakos-Kay-Alamouti system to improve performance and efficiency. Ling’s method offered a flexible approach, minimizing delay by immediately selecting strong signals while improving reliability for weaker signals through combining, a clear and desirable enhancement.
  • Expectation of Success: The combination was predictable because the base system already included combining diversity reception (from Alamouti). Implementing Ling’s teachings simply involved adding a known threshold-based logic to select the most appropriate, pre-existing reception technique based on channel conditions, a straightforward and well-understood engineering optimization.

4. Key Claim Construction Positions

• The Petitioner asserted that no claim terms required express construction. However, it noted that a district court in related litigation construed the term "acknowledgement" as "a message sent from the primary station to the secondary station indicating the primary station's receipt of the secondary station's request." The Petitioner contended its arguments prevailed under both this construction and the term's plain and ordinary meaning.

5. Arguments Regarding Discretionary Denial

• The Petitioner argued that the Board should not exercise its discretion to deny institution under §314 or §325(d).
• Citing General Plastic factors, Petitioner asserted that this was its first petition against the ’079 patent, it challenged claims (1-5, 7) not previously challenged in other IPRs, and it introduced new prior art references (Ling and Dent) not used in prior petitions by other parties.
• Citing Becton Dickinson factors, Petitioner argued that the Office had not previously considered the specific arguments and combinations of art presented in the petition, particularly those including Ling and Dent, and therefore denying institution would be inappropriate.

6. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 1-5, 7, and 17 of the ’079 patent as unpatentable.