BlackBerry Corp v. Optis Wireless Technology LLC

1. Case Identification

• Case #: IPR2017-00754
• Patent #: 8,019,332
• Filed: January 23, 2017
• Petitioner(s): BlackBerry Corp.
• Patent Owner(s): Optis Wireless Technology, LLC
• Challenged Claims: 1-3, 5-8, and 10

2. Patent Overview

• Title: Method for Allocating Control Channel
• Brief Description: The ’332 patent discloses methods for a User Equipment (UE) in a 3GPP Long Term Evolution (LTE) system to efficiently search for and decode control information on a Physical Downlink Control Channel (PDCCH). The invention aims to reduce UE power consumption by defining a limited, UE-specific "search space" determined by a hashing function that calculates a starting position for decoding PDCCH candidates.

3. Grounds for Unpatentability

Ground 1: Obviousness over R1-081101, Knuth, and L’Ecuyer - Claims 1-3, 5-8, and 10 are obvious over R1-081101 in view of Knuth and L’Ecuyer.

• Prior Art Relied Upon: R1-081101 (Ericsson, 3GPP TSG-RAN WG1 #52 contribution, Feb. 15, 2008), Knuth ("The Art of Computer Programming, Volume 2," 2nd ed. 1981), and L’Ecuyer ("Efficient and Portable Combined Random Number Generators," Communications of the ACM, 1988).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that the combination of references taught every limitation of the challenged claims. R1-081101, a 3GPP standards contribution published before the ’332 patent’s priority date, disclosed the foundational method of using a UE-specific search space for PDCCH blind decoding. Specifically, R1-081101 taught calculating a starting point for the search space using a hashing function: Start = (K*x+L) mod floor(#CCEs / aggregation_level). Petitioner asserted this formula maps directly to the claimed "modulo 'C' operation, wherein 'C' is determined as 'floor(N/L)'."
  • Petitioner contended that the one key element not explicitly in R1-081101—the recursive formula Yk=(A*Yk-1)mod D—was a well-known Linear Congruential Generator (LCG) for creating pseudo-random number sequences, as exhaustively detailed in the foundational computer science textbook by Knuth. Petitioner argued that the linear function (K*x+L) in R1-081101 and the LCG in Knuth served the identical purpose of generating a number to be used in a modulo operation and were well-known alternatives.
  • For dependent claims, Petitioner argued R1-081101 explicitly disclosed the aggregation levels of 1, 2, 4, and 8 (claim 3). For claim 2, Petitioner asserted that Knuth taught common modulus values (like 65537 for D) and methods for selecting the multiplier (A), making the claimed values the result of routine experimentation. For claim 5, Petitioner argued that translating the starting index into specific Control Channel Element (CCE) positions was an obvious implementation detail, given that R1-081101 taught that CCEs within a candidate are contiguous. Apparatus claims 6-8 and 10 were argued to be obvious for the same reasons as their corresponding method claims.
  • Motivation to Combine: Petitioner provided three primary motivations for a Person of Ordinary Skill in the Art (POSITA) to combine the references. First, a POSITA would combine R1-081101 and Knuth because the simple linear function in R1-081101 could be readily replaced with Knuth’s well-known LCG to improve the pseudo-random distribution of search space starting positions, a desirable characteristic for avoiding persistent collisions between UEs. Second, L'Ecuyer taught that combining hashing functions, such as two LCGs, was a known technique to increase the period of a random number generator and further reduce collisions. The claimed method, which effectively uses Knuth’s LCG as an input to R1-081101’s outer modulo function, represented just such a combination. A POSITA would be motivated to implement this combination to maximize the period before a starting position repeats, which is especially important when the number of possible starting positions (the value 'C') is small.
  • Expectation of Success: Petitioner asserted a POSITA would have a reasonable expectation of success because combining these well-understood components for their intended and predictable purposes—generating pseudo-random numbers to define a search space—involved no technical hurdles. The behavior of LCGs and modulo arithmetic was thoroughly documented in the art.

4. Key Claim Construction Positions

• "contiguously located from a position": Petitioner proposed this phrase should be interpreted to mean that a plurality of CCEs are sequentially located from a starting point without any gaps. This construction was argued to be supported by the specification and necessary to map the teachings of R1-081101, which explicitly stated that "CCEs in a set are contiguous."
• "using a variable of Yk": Petitioner argued this phrase should be interpreted broadly to mean that a variable Yk is included in a formula, without specifying the exact mathematical operations performed on it. This construction supported Petitioner's argument that the function (K*x + L) from R1-081101 corresponded to the claimed variable Yk.
• "modulo 'C' operation": Petitioner proposed this meant a mathematical operation in which 'C' is the modulus (e.g., X mod C). This construction was central to mapping the hashing function mod floor(#CCEs / aggregation_level) from R1-081101 to the claimed operation.

5. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 1-3, 5-8, and 10 of the ’332 patent as unpatentable under 35 U.S.C. §103.