CommScope Technologies LLC v. Dali Wireless Inc

1. Case Identification

• Case #: IPR2020-01408
• Patent #: 10,045,314
• Filed: July 31, 2020
• Petitioner(s): CommScope Technologies LLC
• Patent Owner(s): Dali Wireless Inc.
• Challenged Claims: 1-20

2. Patent Overview

• Title: Distributed Antenna Systems
• Brief Description: The ’314 patent is directed to a distributed antenna system (DAS) that performs delay compensation. The system introduces delays to signals traveling between a central hub and various remote units to compensate for differences in signal travel time caused by varying distances.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1, 3, 5, 7-18, and 20 by Sabat

• Prior Art Relied Upon: Sabat (Application # 2009/0180426).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Sabat disclosed every limitation of the challenged claims. Sabat’s digital DAS included a hub (310), which functioned as the claimed Digital Access Unit (DAU), interfacing between a base station and multiple remote radio units. Critically, Sabat taught a “Sum/Split & Delay Buffer” (314) within the hub, which performed the functions of the claimed “delay compensation merge unit” by using programmable delay buffers to time-align uplink signals from different remote units and a summer to merge them into a combined data stream. Sabat also disclosed packetizing signals using CPRI/OBSAI protocols, as required by various dependent claims.

Ground 2: Obviousness of Claims 2, 6, and 19 over Sabat in view of Seki

• Prior Art Relied Upon: Sabat (Application # 2009/0180426) and Seki (Application # 2011/0237178).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that to the extent Sabat was found not to teach integrating delay compensation merge units within the remote units themselves (claim 2) or arranging them in a daisy-chain configuration (claim 6), Seki explicitly taught these features. Seki disclosed a wireless network utilizing "distributed cascaded remote radio heads" in a "chain topology" (i.e., a daisy-chain). Furthermore, Seki taught performing delay compensation and signal merging (summing) within each remote radio head along the chain to compensate for delays.
  • Motivation to Combine (for §103 grounds): A POSITA would combine Sabat and Seki to gain the well-known benefits of daisy-chaining, such as reduced cabling costs, ease of installation, and scalability, particularly in common DAS deployments like tunnels or large buildings. Both references addressed the same technical field (DAS) and used the same communication protocol (CPRI), making their combination straightforward and predictable.
  • Expectation of Success (for §103 grounds): A POSITA would have a reasonable expectation of success because implementing Seki’s daisy-chain and remote delay compensation topology within Sabat’s DAS framework was a predictable implementation of known design choices.

Ground 3: Obviousness of Claims 1-8, 10-11, and 13-20 over Kummetz in view of Stuart

• Prior Art Relied Upon: Kummetz (Application # 2010/0278530) and Stuart (Application # 2009/0046586).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner asserted that Kummetz disclosed a digital DAS with nearly all elements of claim 1, including master units (DAUs), a plurality of daisy-chained remote units, and summers for merging uplink signals. However, Kummetz only mentioned "delay elements" without providing a detailed discussion of delay compensation. Stuart remedied this deficiency by teaching a specific method for delay management in a DAS, including systems with daisy-chained remotes. Stuart taught using programmable FIFO delay blocks in each remote unit to independently adjust for signal path delays, thereby achieving synchronization across the network.
  • Motivation to Combine (for §103 grounds): A POSITA would be motivated to combine Stuart’s delay compensation method with Kummetz’s DAS architecture because Stuart was intended for exactly the type of system described by Kummetz. The combination would solve the "common issue" of synchronizing antennas at different distances from the host unit, a known goal in the art. Stuart’s method offered advantages like simplicity and avoiding expensive GPS timing, providing further motivation for its adoption.
  • Expectation of Success (for §103 grounds): The combination was predictable, as it involved applying a known delay compensation solution (Stuart) to a standard DAS architecture (Kummetz) to achieve a desired and expected result (signal synchronization).

• Additional Grounds: Petitioner asserted additional obviousness challenges, including combining Sabat with Sabat ’552 to teach coupling multiple DAUs; combining Sabat with Kummetz to add downlink signal summing; and combining Kummetz and Stuart with Sabat ’552 or Wu to further support the coupling of multiple DAUs.

4. Key Claim Construction Positions

• "delay compensation merge unit configured to delay signals": Petitioner argued this claim 1 term should be construed under 35 U.S.C. §112(f) as a means-plus-function limitation.
  • Proposed Function: (1) applying delay to input signals to compensate for differences in delay, and (2) merging the delay-compensated signals into a combined data stream.
  • Proposed Structure: A delay block programmed to apply delay and a summer that sums the compensated signals. This construction is critical for mapping prior art components like buffers and summers to this limitation.
• "Digital Access Unit (DAU)": Petitioner contended this is not a standard term in the art and is defined by the patent’s specification as "an interface between a base station and digital remote units." This construction allows prior art "hubs" or "master units" that perform this function to satisfy the claim element.

5. Key Technical Contentions (Beyond Claim Construction)

• Flawed Prosecution History: Petitioner argued that the patent was issued due to a significant examiner error. The Examiner’s Reasons for Allowance cited limitations (e.g., "a plurality of DAUs," "a plurality of Base Transceiver Stations") that were present in the provisional application but are absent from the issued independent claim 1. Petitioner contended this error resulted in the issuance of overly broad claims that read directly on the prior art, warranting a skeptical review by the Board.

6. Arguments Regarding Discretionary Denial

• Petitioner argued against discretionary denial under §314(a), despite a co-pending district court case, for several reasons:
  • The IPR challenges many claims (15 of 20) that are not at issue in the district court action.
  • The PTAB’s final written decision would likely issue before the district court trial date.
  • The petition presents a strong case of invalidity on the merits, particularly in light of the alleged examiner error during prosecution.
  • The district court case was in its early stages, with no claim construction or expert discovery completed.

7. Relief Requested

• Petitioner requested the institution of an inter partes review and cancellation of claims 1-20 of the ’314 patent as unpatentable.