Commscope Technologies LLC v. Dali Wireless Inc.

Court of Appeals for the Federal Circuit·Decided August 24, 2021·No. 20-1817·Published

Opinion

Case: 20-1817 Document:49 Page:1 _ Filed: 08/24/2021

GAnited States Court of Appeals for the Federal Circuit

COMMSCOPE TECHNOLOGIES LLC, COMMSCOPE CONNECTIVITY LLC, Plaintiffs-Appellants

Vv.

DALI WIRELESS INC., Defendant-Cross-Appellant

2020-1817, 2020-1818

Appeals from the United States District Court for the Northern District of Texas in No. 3:16-cv-00477-M, Chief Judge Barbara M.G. Lynn.

Decided: August 24, 2021

PHILIP P. CASPERS, Carlson, Caspers, Vandenburgh & Lindquist, P.A., Minneapolis, MN, argued for plaintiffs-appellants . Also represented by WILLIAM F. BULLARD, SAMUEL A. HAMER.

CHARLES HARDY DAVIS, Goldstein & Russell, P.C., Bethesda , MD, argued for defendant-cross-appellant. Also represented by ERIC F. CITRON; CRISTOFER LEFFLER, Folio Law Group PLLC, Lake Forest Park, WA.

Case: 20-1817 Document:49 Page:2 _ Filed: 08/24/2021

2 COMMSCOPE TECHNOLOGIES LLC v. DALI WIRELESS INC.

Before REYNA, SCHALL, and STOLL, Circuit Judges. STOLL, Circuit Judge.

CommScope and Dali each appeal from the district court’s entry of judgment after it denied their motions for judgment as a matter of law, for a new trial, and for attorneys ’ fees. This appeal and cross-appeal involve several patents and numerous issues regarding infringement and validity, but our opinion focuses on only two: infringement and validity of U.S. Patent No. 9,031,521. Although we have thoroughly considered the other issues raised by both parties, we affirm the district court’s determinations as to those issues without significant discussion. As to the 521 patent, for the reasons discussed below, we reverse the district court’s denial of JMOL of no infringement and affirm its denial of JMOL of invalidity.

BACKGROUND

CommScope Technologies LLC and CommScope Connectivity LLC (Collectively, “CommScope”) filed suit against Dali Wireless Inc. (“Dali”) in the United States District Court for the Northern District of Texas alleging infringement of five of CommScope’s patents relating to telecommunications technology. Dali counterclaimed, alleging CommScope infringed two of Dali’s patents also relating to telecommunications technology.

One of those asserted patents, the 521 patent, is assigned to Dali and is titled “System and Method for Digital Memorized Predistortion for Wireless Communication.” This technology generally relates to wireless communications with portable equipment and handsets, such as mobile phones. 521 patent col. 1 ll. 19-23; see also id. at col. 4 ll. 18-23. Such devices often include a power amplifier to boost the signal. However, amplification can cause unintended distortions to the signal. Jd. at col. 1 ll. 36—40, 54-67. The 521 patent resolves this problem through the

Case: 20-1817 Document:49 Page:3 _ Filed: 08/24/2021

COMMSCOPE TECHNOLOGIES LLC v. DALI WIRELESS INC. 3

use of a feedback loop and lookup tables, as described below .

Specifically, the 521 patent describes a training mode (Fig. 3), in which the feedback loop runs and the lookup tables are updated, and an operating mode (Fig. 4), in which the “switch ON/OFF controllers” are turned off and the lookup table is no longer updated. Jd. at col. 5 1. 55— col. 71. 30. In training mode, the feedback loop on the bottom half of Figure 3 uses the output signal fed back from power amplifier 16 to calculate digital predistortion values that are stored in lookup tables 311 & Q.

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These lookup table values are used in operating mode to intentionally “predistort” the signal before the signal is sent to the power amplifier in a way such that after the signal is amplified, it is not distorted.

1 For the 521 patent figures, we have included the versions from CommScope’s briefs, which are clearer versions of the figures than those in the ’521 patent. Compare Appellants’ Br. 9, with 521 patent Fig. 3.

Case: 20-1817 Document:49 Page:4 _ Filed: 08/24/2021

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Id. Fig. 4 (depicting operating mode), col. 6 ll. 27-41. Claim 1 of the 521 patent recites:

1. A method of operating a power amplifier, the method comprising:

initializing the power amplifier;

performing a training phase comprising:

establishing pre-computed distortion contributions based on pre-compensation training feedback signals representative of output of the power amplifier; and

storing the pre-computed distortion contributions in a lookup table; and

performing an operating phase comprising:

switching a controller off to disconnect signal representative of the output of the power amplifier ;

accepting an original value that reflects information to be communicated;

generating a digital lookup table key based on the original value;

retrieving from the lookup table, using the digital lookup table key, a corresponding pre-

Case: 20-1817 Document:49 Page:5 _ Filed: 08/24/2021

COMMSCOPE TECHNOLOGIES LLC v. DALI WIRELESS INC. 5

computed distortion contribution for the original value;

distorting the original value based on the corresponding pre-computed distortion contribution to obtain a distorted value to precompensate for the nonlinear characteristics of the power amplifier; and

wirelessly transmitting a pre-distorted signal based on the distorted value.

Id. at col. 10 1. 47-col. 11 1. 4 (emphasis added to disputed limitation).

Dali accused CommScope’s FlexWave Prism distributed antenna system (FlexWave) of infringing the 521 patent . According to CommScope, this system is installed on telephone poles to extend wireless coverage. Appellants’ Br. 12. Similar to the 521 patent, the FlexWave system analyzes a feedback signal from a power amplifier to calculate predistortion. Unlike the 521 patent, the FlexWave uses two power amplifiers. The dispute between the parties centers on the FlexWave’s selector switch (labeled “SW” in the figure below), which continuously chooses between feedback signals from the two power amplifiers for calculating predistortion values:

Case: 20-1817 Document:49 Page:6 _ Filed: 08/24/2021

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Id. at 14 (depicting the accused FlexWave).

The claim limitation at the center of the parties’ infringement dispute is the first step in the claimed “operating phase”: “switching a controller off to disconnect signal representative of the output of the power amplifier.” 521 patent col. 10 ll. 57-58 (emphasis added). The district court construed this term to mean “[s]witching a controller to a nonoperating state to disconnect signal representative of the output of the power amplifier.”, CommScope Techs. LLC v. Dali Wireless, Inc. (Claim Construction Order), No. 3:16-cv-477, 2017 WL 6549933, at *12 (N.D. Tex. Dec. 19, 2017).

At trial, CommScope argued that three pieces of prior art anticipated the asserted claims of the 521 patent—

Case: 20-1817 Document:49 Page:7 Filed: 08/24/2021

COMMSCOPE TECHNOLOGIES LLC v. DALI WIRELESS INC. 7

Wright,? Bauder,? and Khan.4 Wright is particularly relevant to our decision on appeal.

Like the 521 patent, Wright discloses a system for digital predistortion that uses a feedback signal from a power amplifier to calculate predistortion values. Like the accused FlexWave device, Wright’s system includes multiple power amplifiers (601:-n) and a switch (Multiplexer (“MUX”) 106) that selects one of the feedback signals from one of the power amplifiers.

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Commscope Technologies LLC v. Dali Wireless Inc., (Fed. Cir. 2021).

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