PTAB

IPR2020-00238

Ericsson Inc v. Sol IP LLC

Log In
Key Events
Petition
petition Intelligence

1. Case Identification

2. Patent Overview

  • Title: Carrier Aggregation in Wireless Communication Systems
  • Brief Description: The ’936 patent discloses a method for receiving data in a wireless communication system using carrier aggregation. The technology involves transmitting Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) symbols across two time slots, where data symbols are multiplied by specific length-five DFT orthogonal sequences, and employing a "slot-level remapping" scheme to randomize interference between user terminals.

3. Grounds for Unpatentability

Ground 1: Obviousness over Nazar in view of TI-1 or Motorola-1 - Claim 12 is obvious over Nazar in view of TI-1 or Motorola-1.

  • Prior Art Relied Upon: Nazar (Patent 9,485,060), TI-1 (3GPP Contribution R1-080707), and Motorola-1 (3GPP Contribution R1-082330).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Nazar, a §102(e) reference, teaches nearly all elements of claim 12. Nazar discloses a DFT-S-OFDM based Physical Uplink Control Channel (PUCCH) structure for carrier aggregation where data symbols transmitted across two slots are multiplied by a length-5 orthogonal block spreading code. Nazar further teaches that these codes can be DFT codes generated from a DFT matrix to enable multiplexing of up to five users. Crucially, Nazar discloses a general "time-domain cover-code remapping scheme" performed at the slot-level to randomize interference. Petitioner asserted the only element not explicitly disclosed in Nazar is the precise sequence index remapping pattern recited in claim 12’s Table 4.
    • Motivation to Combine: Petitioner contended a person of ordinary skill in the art (POSITA) would combine Nazar’s system with the teachings of TI-1 or Motorola-1 to implement a specific, effective remapping scheme. Nazar identifies the problem of interference and proposes a generic slot-level remapping solution without specifics. TI-1 and Motorola-1, both from the same field of PUCCH design, provide detailed, well-understood solutions to the same problem. They explicitly teach slot-level remapping schemes where sequence indices that are adjacent in a first slot are mapped to non-adjacent indices in a second slot to randomize interference. A POSITA would thus be motivated to implement these known, beneficial remapping techniques to improve upon Nazar's generalized disclosure.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success because combining the references involves applying a known interference randomization technique (from TI-1 or Motorola-1) to a similar system (Nazar's PUCCH format). The underlying interference principles are identical, and the modification would be a predictable implementation of a known solution to a known problem. Petitioner asserted that for a set of five sequence indices, only two remapping patterns exist that map all adjacent indices to non-adjacent ones, and the pattern in claim 12’s Table 4 is one of them, making its selection an obvious design choice.

Ground 2: Obviousness over Ericsson-2 in view of TI-1 or Motorola-1 - Claim 12 is obvious over Ericsson-2 in view of TI-1 or Motorola-1.

  • Prior Art Relied Upon: Ericsson-2 (3GPP Contribution R1-103506), TI-1 (3GPP Contribution R1-080707), and Motorola-1 (3GPP Contribution R1-082330).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Ericsson-2 discloses a carrier aggregation transmission scheme that meets all limitations of claim 12 except for the specific slot-level remapping defined by Table 4. Ericsson-2 teaches transmitting data across a first and second slot, where data symbols are multiplied by orthogonal DFT sequences of length five. This system is designed to enable multiplexing of up to five users within the same resource blocks. Petitioner noted that Ericsson-2 is silent on whether the orthogonal sequence used in the first slot should be the same as or different from the sequence used in the second slot, presenting a design choice.
    • Motivation to Combine: As Ericsson-2 is silent on remapping, a POSITA seeking to optimize performance would be motivated to incorporate a known interference randomization technique. A POSITA would naturally look to contemporaneous art in the same field, such as TI-1 and Motorola-1, which directly address interference in PUCCH transmissions by teaching slot-level remapping. The motivation would be to enhance the Ericsson-2 system with the known and beneficial effects of randomizing interference by ensuring adjacent sequences in the first slot are not adjacent in the second slot, a technique explicitly taught by both TI-1 and Motorola-1.
    • Expectation of Success: The combination would yield predictable results. A POSITA would expect that applying the remapping schemes from TI-1 or Motorola-1 to the Ericsson-2 PUCCH structure would successfully randomize interference without disrupting the system's fundamental operation. The modification would be minor—simply defining the selection of the second slot's sequence based on the first—and would be well within the skill of a POSITA. Arriving at the specific pattern of Table 4 was argued to be an obvious choice, as it is one of only two possible patterns that achieve the desired non-adjacent remapping for five sequences.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claim 12 of Patent 8,593,936 as unpatentable.