DCT
6:21-cv-00107
TOT Power Control SL v. AT&T Inc
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: TOT Power Control, S.L. (Spain)
- Defendant: AT&T, Inc. (Delaware), AT&T Corp. (New York), and AT&T Mobility LLC (Delaware)
- Plaintiff’s Counsel: Porter Hedges LLP
- Case Identification: 6:21-cv-00107, W.D. Tex., 02/01/2021
- Venue Allegations: Plaintiff alleges venue is proper in the Western District of Texas because Defendants maintain a regular and established place of business in the District, including retail stores and CDMA-based wireless network infrastructure such as cellular towers.
- Core Dispute: Plaintiff alleges that Defendant’s WCDMA-based wireless communication networks infringe two patents related to methods for outer loop power control.
- Technical Context: The technology at issue addresses power control management in 3rd Generation (3G) cellular networks to optimize network capacity and maintain connection quality by dynamically adjusting signal-to-interference ratio targets.
- Key Procedural History: The complaint alleges that Plaintiff shared its patented techniques with Defendant’s base station equipment suppliers, including Nokia and Ericsson, who allegedly adopted the technology without a license. No prior litigation, licensing history with the Defendant, or post-grant proceedings are mentioned in the complaint.
Case Timeline
| Date | Event |
|---|---|
| 2005-08-17 | Priority Date for ’376 and ’865 Patents |
| 2009-02-24 | U.S. Patent No. 7,496,376 Issues |
| 2009-05-12 | U.S. Patent No. 7,532,865 Issues |
| 2021-02-01 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 7,496,376 - Outer Loop Power Control Method and Apparatus for Wireless Communications Systems, issued February 24, 2009
The Invention Explained
- Problem Addressed: In WCDMA wireless systems, conventional outer loop power control (OLPC) adjusts transmission power based on a target block error rate (BLER). The patent asserts this method is slow to react to changing channel conditions, particularly when conditions improve, because measuring BLER takes a long time. This slow reaction can lead to using excessive power, which increases network interference and reduces overall system capacity (Compl. ¶¶14, 17; ’376 Patent, col. 3:1-20).
- The Patented Solution: The patent proposes an OLPC method that supplements the standard BLER-based control. It introduces a system that estimates "fading margins" based on "outage probabilities" and other channel parameters. A "dynamic adjusting function," preferentially a neural network, then maps these fading characteristics to a target signal-to-interference ratio (SIRtarget). This allows the system to adapt power levels more rapidly and precisely to the actual, moment-to-moment conditions of the wireless channel (’376 Patent, Abstract; col. 6:1-12).
- Technical Importance: This approach aims to make power control more responsive to dynamic channel fading, thereby reducing wasted power, minimizing interference, and improving wireless network capacity and quality of service (Compl. ¶18).
Key Claims at a Glance
- The complaint asserts infringement of claims including independent apparatus Claim 6 (Compl. ¶¶28, 30).
- The essential elements of independent Claim 6 include:
- An outer loop power control apparatus with at least one programmable electronic device operable to perform steps including:
- establishing a target block error rate (BLERtarget);
- calculating an estimate of a received signal-to-interference ratio (SIRrec) and of fading parameters in the channel;
- estimating fading margins associated with outage probabilities;
- indicating the status of data blocks based on a Cyclic Redundancy Code (CRC) check; and
- establishing a target SIR (SIRtarget) using a "dynamic adjusting function" that maps a quality criterion based on the outage probabilities to a quality criterion based on the target BLER, thereby adapting power to the channel's propagation conditions.
- The complaint notes infringement of claims "including but not limited to Claims 1 and 6," suggesting other claims may be asserted later (Compl. ¶28).
U.S. Patent No. 7,532,865 - Outer Loop Power Control Method and Device for Wireless Communications Systems, issued May 12, 2009
The Invention Explained
- Problem Addressed: The patent addresses the "wind-up" problem in OLPC systems. Wind-up occurs when a mobile device's signal quality degrades severely (e.g., upon entering a tunnel), causing the system to drive the SIRtarget to an unattainably high level. When the signal condition later improves, the system is very slow to "unwind" and lower the SIRtarget back to an appropriate level. This prolonged period of high SIRtarget creates unnecessary interference for other users and wastes system capacity (’865 Patent, col. 3:1-17; Compl. ¶14).
- The Patented Solution: The invention provides a method to accelerate the "unwinding" process. It involves detecting the start of the unwinding phase (i.e., when the channel conditions improve) and then immediately modifying the SIRtarget to a value that matches or is close to the value it had just before the wind-up began. This avoids the slow, step-by-step reduction process of conventional systems (’865 Patent, Abstract; col. 4:21-34).
- Technical Importance: By rapidly resetting the SIRtarget after a wind-up event, the invention is designed to shorten the recovery time, reduce interference, and thereby increase overall system capacity and connection quality (Compl. ¶21).
Key Claims at a Glance
- The complaint asserts infringement of claims including independent method Claim 1 (Compl. ¶¶39, 41).
- The essential elements of independent Claim 1 include:
- An outer loop power control method comprising steps of:
- estimating a received SIR (SIRrec);
- setting a target SIR (SIRtarget) during the normal mode of operation;
- detecting the start of an outer loop wind-up;
- setting a specific SIRtarget during the wind-up; and
- detecting the start of the outer loop unwinding, at which point the SIRtarget is "modified... to match it to the outer loop power control in normal mode just prior to the start of the outer loop wind up."
- The complaint notes infringement of claims "including but not limited to Claims 1 and 5," suggesting other claims may be asserted later (Compl. ¶39).
III. The Accused Instrumentality
- Product Identification: The accused instrumentalities are Defendants' WCDMA-based wireless networks and their component base transmission stations ("BTS"), which include Radio Network Controllers ("RNC") and Node-Bs (Compl. ¶¶30, 41).
- Functionality and Market Context: The complaint alleges that these networks provide wireless voice, messaging, and data services throughout the United States (Compl. ¶9). The relevant technical functionality is the implementation of outer loop power control processes for the WCDMA network, which are governed by the 3GPP UMTS standard (Compl. ¶¶12, 31). The complaint alleges that these networks utilize equipment supplied by Nokia and Ericsson (Compl. ¶30) and that the implementation of the patented techniques provides Defendants with "significant capacity gains" (Compl. ¶22). The complaint includes a figure illustrating the conventional process of adjusting SIRtarget, showing a large increase after a single block error and a slow decrease over 99 correct blocks, which sets the stage for the patented improvements (Compl. p. 6).
IV. Analysis of Infringement Allegations
'376 Patent Infringement Allegations
| Claim Element (from Independent Claim 6) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| An outer loop power control apparatus for wireless communications systems, comprising at least one programmable electronic device the programmable electronic device operable to... perform the steps of: | Defendants' WCDMA BTS are comprised of processors that manage inner and outer loop power control processes. | ¶31 | col. 8:1-4 |
| establishing a target block error rate (BLERtarget) | Defendants' WCDMA BTS maintain a configurable parameter for the Block Error Rate Target. | ¶32 | col. 14:48-49 |
| calculating an estimate (701) of a desired signal to interference ratio (SIRrec) and of some fading parameters in a channel (706) which characterize the data signal... received | Defendants' WCDMA BTS measure the received SIR value (SIRRec) and estimate fading by comparing measured SIRRec values to the SIRTarget values. | ¶¶33-34 | col. 14:50-54 |
| estimating some fading margins (M1, M2, . . . , MN) associated with some outage probabilities (po1, po2, . . . , poN) and with the fading parameters in the channel (706) | Defendants' WCDMA BTS use collected SIR error values to determine a distribution and calculate a fading margin. A graph in the complaint illustrates this relationship between SIR error distribution and fading margin (Compl. p. 13). | ¶35 | col. 14:55-58 |
| indicating a status of the data blocks (707) based on the checking of a Cyclic Redundancy Code (CRC) | Defendants' WCDMA BTS adjust the SIRTarget value based on block/frame errors indicated by CRC errors per the 3GPP UMTS standard. | ¶36 | col. 14:55-58 |
| establishing a target desired signal to interference ratio (SIRtarget) for the outer loop, based on... the fading margins... and the target block error... by means of a dynamic adjusting function which performs a mapping... so that the power is adapted to the propagation conditions... | Defendants' WCDMA BTS allegedly adjust the SIRTarget value using both the standard BLER-based mechanism and the calculated fading margin values. | ¶37 | col. 14:61-67 |
'865 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| estimating a desired signal to interference ratio received (SIRrec) based on a data signal... | Defendants' WCDMA BTS measure the received SIR value (SIRRec) as part of the outer loop power control mechanism required by the 3GPP UMTS Standard. | ¶42 | col. 8:47-49 |
| setting a desired signal to interference ratio target (SIRtarget) that is close to a signal to interference ratio required (SIRreq) during the normal mode of the outer loop | Defendants' WCDMA BTS adjust the SIRTarget value based on block/frame errors indicated by CRC, as part of the standard outer loop power control mechanism. | ¶43 | col. 8:50-53 |
| detecting a start (402) of the outer loop wind-up | Defendants' WCDMA BTS allegedly detect a "wind-up" condition based on repeated CRC block errors that lead to frequent, repeated increases in the SIRTarget value. | ¶44 | col. 8:54-55 |
| setting a specific desired signal to interference ratio target (SIRtarget) during the outer loop wind-up | Defendants' WCDMA BTS allegedly limit the increases in the SIRTarget value, capping it at a predetermined value during the "wind-up" condition. | ¶45 | col. 8:56-58 |
| detecting a start (403) of the outer loop unwinding, wherein the desired signal to interference ratio target (SIRtarget) is modified... to match it to the outer loop power control in normal mode just prior to the start of the outer loop wind up | Defendants' WCDMA BTS allegedly detect the end of the "wind-up" condition based on the cessation of repeated CRC block errors and then adjust the SIRTarget to a value consistent with the value before the "wind-up" condition began. | ¶46 | col. 8:58-65 |
- Identified Points of Contention:
- '376 Patent: A central issue may be whether the accused systems perform the claimed step of "establishing a target... SIR... by means of a dynamic adjusting function which performs a mapping" using "fading margins." The complaint alleges this functionality, but the technical evidence required to prove that the accused system's algorithm constitutes the claimed "mapping" based on "fading margins"—as opposed to a conventional BLER-based adjustment—will be a key focus.
- '865 Patent: The dispute will likely center on the claim limitation requiring that the SIRtarget is "modified... to match" the pre-wind-up value. A question for the court will be whether the accused system performs a specific, discrete modification step as claimed, or whether it simply resumes a standard operational mode that eventually, but not directly, returns the SIRtarget to a normal level.
V. Key Claim Terms for Construction
'376 Patent: "dynamic adjusting function which performs a mapping" (Claim 6)
- Context and Importance: This term defines the core novel element of the ’376 Patent's claimed apparatus. The outcome of the infringement analysis will heavily depend on how broadly or narrowly this functional language is construed.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claim uses broad functional language, not tying the invention to a specific algorithm. The specification describes a neural network as a "preferential" implementation, which may suggest that other types of functions that perform the same mapping are also covered (’376 Patent, col. 6:15-17).
- Evidence for a Narrower Interpretation: The specification provides a detailed description and figures (e.g., Fig. 5) of a two-layer neural network as the means for implementing the function. A defendant may argue that these specific embodiments limit the scope of the claim term to such a neural network or a structurally equivalent system (’376 Patent, col. 12:47-67).
'865 Patent: "modified at the start... of the outer loop unwinding, to match it to the outer loop power control in normal mode just prior to the start of the outer loop wind up" (Claim 1)
- Context and Importance: This phrase captures the specific, inventive action for recovering from a "wind-up" state. The interpretation of "modified... to match" will be critical to determining infringement.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: Plaintiff may argue that the term covers any process that, upon detecting the start of unwinding, actively and rapidly resets the SIRtarget to its pre-wind-up level, distinguishing it from a passive, slow decay.
- Evidence for a Narrower Interpretation: The specification describes returning the SIRtarget to the "last correct value (401) ... set before stopping the running of the outer loop power control in normal mode" (’865 Patent, col. 7:27-32). A defendant may argue this requires a specific operation of storing, recalling, and setting the SIRtarget to this discrete historical value, and that a mere resumption of normal algorithm operation does not constitute "matching."
VI. Other Allegations
- Indirect Infringement: The complaint does not plead specific counts for indirect infringement. While it alleges Defendants use infringing equipment supplied by third parties (Compl. ¶22), it does not allege the specific elements of knowledge and intent required to state a claim for induced or contributory infringement.
- Willful Infringement: The complaint does not contain an explicit allegation of willful infringement and does not allege that Defendants had pre-suit knowledge of the patents-in-suit.
VII. Analyst’s Conclusion: Key Questions for the Case
This case appears to center on highly technical questions of how the accused WCDMA network equipment operates at the software and algorithm level. The key questions for the court will likely be:
A central question of evidentiary proof: Does the accused AT&T network employ a power control algorithm that goes beyond the 3GPP standard by using "fading margins" and a "dynamic adjusting function" as required by the ’376 Patent, or does it adhere to a conventional BLER-based system? This is a factual question that will depend heavily on expert discovery and analysis of the accused systems.
A key question of claim construction and function: For the ’865 Patent, can the claim language "modified... to match" be met by a system that simply resumes its normal operating algorithm after a wind-up event, or does it require a specific, discrete software instruction to recall a prior value and apply it? The resolution of this will determine whether the accused system's recovery process performs the claimed invention.