PTAB

IPR2022-00277

Dell Inc v. Neo Wireless LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Channel Probing Signal for a Broadband Communication System
  • Brief Description: The ’908 patent describes a broadband wireless communication system where a spread spectrum signal is intentionally overlapped with an orthogonal frequency division multiplexing (OFDM) signal, and discloses methods to minimize mutual interference between the signals.

3. Grounds for Unpatentability

Ground 1: Obviousness of Claims 1-6, 8-16, 18-26, and 28-30 over Ma in view of TR

  • Prior Art Relied Upon: Ma (Application # US20040001429) and TR (ETSI TR 101 146 V3.0.0).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Ma disclosed a wireless communication system using an OFDM-based uplink interface with different transmission modes and a Random Access Channel (RACH) for user equipment to access the system. Ma taught transmitting OFDM-based uplink signals and a separate random access signal, which could be a spread spectrum signal. However, Petitioner contended Ma did not explicitly teach a guard period following the random access signal. TR, an ETSI technical report on OFDMA proposals, explicitly taught using a guard period following a RACH burst to account for unknown propagation delays and compensate for timing misalignments. TR disclosed that a RACH transmission could occupy one of two prepared time slots, leaving the second empty as a guard time.
    • Motivation to Combine: Petitioner asserted that a person of ordinary skill in the art (POSITA) would combine the teachings of TR with Ma's system. The motivation was to solve the known problem of unknown propagation delay associated with random access signals, a problem explicitly addressed by TR’s use of a guard period. Implementing TR’s guard time feature into Ma’s OFDMA system was presented as a straightforward application of a known technique to a known system to achieve predictable results, such as improved system robustness and reliable signal reception.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success because both Ma and TR relate to similar OFDMA-based communication systems and address common problems like random access. The combination represented a predictable integration of complementary features within the same technical field.

Ground 2: Anticipation/Obviousness of Claims 1-6, 8-16, 18-26, and 28-30 over Walton

  • Prior Art Relied Upon: Walton (Application # US20040082356).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that Walton, a single reference, disclosed every limitation of the challenged claims. Walton described a MIMO-OFDM wireless system where a user terminal transmits uplink signals, including data on a Reverse Channel (RCH) and access requests on a RACH. Petitioner mapped the "first uplink signal" to Walton’s RCH packet, which comprised OFDM symbols and utilized a frame format of PHY frames. The "random access signal followed by a guard period" was mapped to Walton's disclosure that a RACH segment explicitly included a "guard interval" at the end to prevent interference. Walton further taught that its overall system bandwidth was partitioned into orthogonal subbands, with some remaining unused as "guard subbands," thereby meeting the limitation that the random access signal occupies "only a portion of the frequency band."
    • Key Aspects: The core of this ground was that Walton provided a complete blueprint for the claimed invention. It described the fundamental structure of an uplink frame with distinct channels, including a random access channel that was explicitly followed by a guard interval for the exact purpose of managing transmission timing, anticipating the core concept of the challenged claims.

  • Additional Grounds: Petitioner asserted additional obviousness challenges against claims 10, 20, and 30 by adding Jung (Application # US20040114504A1) to the primary combinations (Ma/TR and Walton). Jung was cited to explicitly teach well-known, standard components of an OFDM transmitter (e.g., serial-to-parallel converter, IFFT unit, cyclic prefix addition circuit) that Petitioner argued a POSITA would have inherently understood to be part of the transmitters in Ma, TR, and Walton.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under Fintiv was inappropriate. The petition was filed early in the parallel district court litigation, before a scheduling order was issued, before any significant investment in discovery, and well before the one-year statutory bar. Petitioner highlighted that the merits of the petition were particularly strong, relying on prior art not considered during prosecution. To further eliminate overlap and promote judicial efficiency, Petitioner submitted a stipulation agreeing not to pursue in district court any invalidity ground raised or that could have been reasonably raised in the IPR if review was instituted.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-6, 8-16, 18-26, and 28-30 of the ’908 patent as unpatentable.