PTAB

IPR2016-01021

Cisco Systems, Inc. v. TQ Delta LLC

Title: System and Method for Scrambling the Phase of the Carriers in a Multicarrier Communications System
Brief Description: The ’158 patent discloses a system and method for reducing the peak-to-average power ratio (PAR) in multicarrier communication systems, such as Digital Subscriber Line (DSL). The technology addresses the problem of high PAR that arises when transmitting the same data bits over multiple carriers by scrambling the phase characteristics of the modulated carrier signals using a pseudo-random number generator.

Prior Art Relied Upon: Shively (Patent 6,144,696) and Stopler (Patent 6,625,219).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Shively taught a discrete multitone transmission (DMT) method for DSL modems that increased data rates by transmitting the same data bit redundantly over multiple, otherwise unusable, power-limited subchannels. Petitioner contended that Stopler taught a multicarrier transmitter that employed a phase scrambler to randomize the phases of carrier signals, specifically to address the known problem of high PAR that can result from transmitting structured, non-random data.
- Motivation to Combine: Petitioner asserted that a person of ordinary skill in the art (POSITA) would have recognized that Shively’s technique of transmitting redundant data bits would inherently create a non-random, structured signal, resulting in an undesirable high PAR. A POSITA would have been motivated to combine Stopler's well-known phase scrambling solution to solve this predictable problem in Shively's analogous multicarrier DSL system.
- Expectation of Success: Combining Stopler’s phase scrambler with Shively’s transmitter was presented as a straightforward application of a known technique to solve a known problem, yielding predictable results.

Prior Art Relied Upon: Shively (Patent 6,144,696), Stopler (Patent 6,625,219), and Gerszberg (Patent 6,424,646).
Core Argument for this Ground:
- Prior Art Mapping: This ground built upon the base combination of Shively and Stopler. Petitioner argued that Gerszberg provided the context for applying these multicarrier technologies, teaching the use of DSL modems (including ADSL and VDSL) to provide specific, desirable services such as high-speed internet access and video services. Dependent claims targeted these specific applications.
- Motivation to Combine: Petitioner stated two primary motivations. First, Shively expressly incorporated Gerszberg by reference, effectively directing a POSITA to its teachings. Second, a POSITA would have been motivated by market forces to apply the improved transmission method of the Shively/Stopler combination to the specific, high-value applications taught by Gerszberg (e.g., VDSL for high-speed internet) to create a more commercially competitive product.

Prior Art Relied Upon: Shively (Patent 6,144,696), Stopler (Patent 6,625,219), and Bremer (Patent 4,924,516).
Core Argument for this Ground:
- Prior Art Mapping: This ground added Bremer to the base combination to address claim limitations related to the receiver. Petitioner asserted that Bremer taught the fundamental principle that a receiver must perform complementary operations to decode a signal modified by a transmitter. Specifically, Bremer disclosed using a "complementary pseudorandom generator" in a receiver to reverse phase modifications performed by a pseudorandom generator in the transmitter.
- Motivation to Combine: Petitioner argued that to create a functional, end-to-end communication system based on the Shively/Stopler transmitter, a POSITA would have needed to design a corresponding receiver. Bremer provided the explicit teaching and design principle for creating a matched receiver capable of descrambling the phase-shifted signals from the transmitter by using a second, complementary pseudo-random number generator. This was necessary to allow the transmitted data to be received and decoded.
Additional Grounds: Petitioner asserted additional obviousness challenges, including a combination adding Gerszberg to the Ground 3 references to teach wireless transceivers (Ground 4), and a combination adding Flammer (Patent 5,515,369) to the Ground 3 references to teach synchronizing the pseudo-random generators by transmitting a seed value (Ground 5).

"multicarrier" (claims 1-30): Petitioner argued this term should be construed to mean "multiple carriers." This construction was based on the specification's description of a "conventional multicarrier communications system" and was important for establishing that the prior art systems, which used multiple carriers, met this limitation.
"transceiver" (claims 1-28): Petitioner proposed construing this term as "a device, such as a modem, with a transmitter and a receiver." This construction, supported by the specification and a dictionary definition, was central to arguing that the DSL and cable modems described in the prior art references satisfied the "transceiver" limitations of the claims.

Petitioner requests institution of an inter partes review and cancellation of claims 1-30 of Patent 8,718,158 as unpatentable.