PTAB

IPR2013-00636

Broadcom Corp v. Telefonaktiebolaget LM Ericsson

Log In
Key Events
Petition
petition Intelligence

1. Case Identification

2. Patent Overview

  • Title: Method for Discarding Packets in a Data Network
  • Brief Description: The ’625 patent discloses a method for managing data packet transmission in a network using an Automatic Repeat Request (ARQ) protocol. The invention centers on a transmitter commanding a receiver to discard outdated or time-sensitive packets to synchronize communication windows and improve bandwidth efficiency, particularly through the use of an "enforcement bit."

3. Grounds for Unpatentability

Ground 1: Anticipation - Claim 1 is anticipated by Garrabrant

  • Prior Art Relied Upon: Garrabrant (Patent 5,610,595).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Garrabrant disclosed every limitation of claim 1. Garrabrant taught a packet radio communication system using sending and receiving windows. When packets were lost, the transmitter sent a "lost" message, which Petitioner contended was the claimed "command." This command instructed the receiver to advance its window upon receipt of the next, non-consecutive packet (e.g., receiving packet #7 after #1, skipping lost packets #2-6). This action allegedly met the limitations of commanding the receiver to accept a non-consecutive packet and to "release any expectation" of receiving the intervening lost packets. Petitioner asserted that Garrabrant also taught the "transmitter discarding" limitation, as it disclosed that a packet is discarded when its retransmit counter decrements to zero.
    • Key Aspects: The argument hinged on construing Garrabrant's "lost" message as the claimed "command" that forces the receiver to resynchronize its reception window.

Ground 2: Anticipation - Claim 1 is anticipated by Hettich

  • Prior Art Relied Upon: Hettich (a 1996 thesis on ARQ protocols).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner contended that Hettich, which described a Selective Reject (SR) ARQ system, anticipated claim 1. Hettich disclosed a transmitter sending a "Delay PDU" (Protocol Data Unit) to a receiver. This Delay PDU specified the highest sequence number (SN) of all discarded cells. Upon receipt, the receiver "stops waiting" for cells with sequence numbers up to and including the specified SN. Petitioner argued that this "Delay PDU" was the claimed "command" and that "stops waiting" was synonymous with "release any expectation of receiving." The transmitter's act of sending the Delay PDU, which is predicated on its decision not to retransmit certain cells, was argued to meet the limitation of the transmitter discarding those packets.

Ground 3: Obviousness - Claim 1 is obvious over Walke in view of Bertsekas

  • Prior Art Relied Upon: Walke (DE 19543280) and Bertsekas (a 1987 textbook titled DATA NETWORKS).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that Bertsekas taught a conventional Go-Back-N ARQ system where packets are expected to be received in strict order. Walke taught a more advanced selective reject system that addressed time-sensitive packets by using a "DELAY" command to explicitly notify a receiver that a specific packet had been discarded (e.g., due to a lifetime timer expiring). The DELAY command instructed the receiver to stop waiting for the discarded packet and adjust its receive window accordingly.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would have been motivated to improve the well-known but rigid Go-Back-N protocol from Bertsekas by incorporating the more flexible packet-discarding mechanism from Walke. The combination would solve the known problem of handling time-sensitive or outdated packets in a Go-Back-N system, preventing unnecessary delays and bandwidth waste.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success in applying Walke's DELAY command concept to a Go-Back-N system. This would involve a predictable modification: when a packet is discarded, the next transmitted packet would carry a command indicating the discard, causing the Go-Back-N receiver to update its window rather than wait for the out-of-sequence packet.

  • Additional Grounds: Petitioner asserted additional challenges, including anticipation by Garrabrant's failure recovery mode (Ground 2), obviousness over Walke alone (Ground 4), and anticipation by Kemp (Patent 6,621,799) (Ground 5). These grounds relied on similar principles of using explicit messages in prior art ARQ systems to manage packet discarding and window synchronization.

4. Key Claim Construction Positions

  • "Commanding": Petitioner argued this term should be construed as "an instruction represented in a control field to cause an addressed device to execute a specific control function." This construction was proposed to counter the Patent Owner's allegedly overbroad position in related litigation that the mere receipt of any data packet constitutes a "command." Petitioner contended its narrower construction was consistent with the ’625 patent's specification, which describes an "enforcement bit" as a specific instruction separate from the packet's data or sequence number. This construction was critical for aligning the explicit control messages in the prior art (e.g., Garrabrant's "lost" message, Hettich's "Delay PDU") with the claim language.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claim 1 of the ’625 patent as unpatentable.