DCT
2:18-cv-00526
Sol IP LLC v. AT&T Mobility LLC
Key Events
Amended Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Sol IP LLC (Virginia)
- Defendant: AT&T Mobility LLC (Delaware)
- Plaintiff’s Counsel: Susman Godfrey LLP; Capshaw Derieux LLP
- Case Identification: 2:18-cv-00526, E.D. Tex., 03/22/2019
- Venue Allegations: Plaintiff alleges venue is proper in the Eastern District of Texas because AT&T maintains a "regular and established" physical presence and place of business in the district, including retail stores, cellular towers, base stations, and Wi-Fi hotspots.
- Core Dispute: Plaintiff alleges that Defendant’s 4G LTE mobile network, and the mobile devices and services operating thereon, infringe twenty-seven patents related to foundational wireless telecommunications technologies.
- Technical Context: The technologies at issue relate to standardized methods for data transmission, error control, and network management within 4G LTE, LTE-Advanced, and Wi-Fi communication systems, which form the backbone of the modern mobile internet.
- Key Procedural History: The complaint alleges that Plaintiff provided Defendant with notice of the asserted patent families via letters in May and June of 2015. It further alleges that the patents' original inventor, the Electronics and Telecommunications Research Institute (ETRI), declared the asserted LTE patents as essential to the LTE standards, which may introduce issues related to Fair, Reasonable, and Non-Discriminatory (FRAND) licensing obligations.
Case Timeline
| Date | Event |
|---|---|
| 2008-06-20 | Earliest Priority Date ('884 Patent) |
| 2011-05-12 | Earliest Priority Date ('256 Patent) |
| 2012-09-18 | U.S. Patent No. 8,270,354 Issued |
| 2012-11-13 | U.S. Patent No. 8,311,031 Issued |
| 2012-11-27 | U.S. Patent No. 8,320,337 Issued |
| 2012-11-27 | U.S. Patent No. 8,320,565 Issued |
| 2012-11-27 | U.S. Patent No. 8,320,571 Issued |
| 2013-11-26 | U.S. Patent No. 8,593,936 Issued |
| 2014-02-18 | U.S. Patent No. 8,654,881 Issued |
| 2014-06-24 | U.S. Patent No. 8,761,814 Issued |
| 2015-03-03 | U.S. Patent No. 8,971,168 Issued |
| 2015-04-14 | U.S. Reissued Patent No. RE45,466 Issued |
| 2015-05-01 | Plaintiff sends "2015 LTE Notice Letter" to Defendant |
| 2015-06-08 | Plaintiff sends "2015 Wi-Fi Notice Letter" to Defendant |
| 2015-09-22 | U.S. Patent No. 9,144,064 Issued |
| 2015-10-06 | U.S. Patent No. 9,155,066 Issued |
| 2015-12-01 | U.S. Patent No. 9,204,438 Issued |
| 2016-02-16 | U.S. Patent No. 9,265,063 Issued |
| 2016-08-30 | U.S. Patent No. 9,432,940 Issued |
| 2016-11-15 | U.S. Patent No. 9,496,976 Issued |
| 2017-03-21 | U.S. Patent No. 9,603,174 Issued |
| 2017-04-25 | U.S. Patent No. 9,634,746 Issued |
| 2018-02-06 | U.S. Patent No. 9,888,435 Issued |
| 2018-02-20 | U.S. Patent No. 9,900,067 Issued |
| 2018-06-26 | U.S. Patent No. 10,009,884 Issued |
| 2018-08-07 | U.S. Patent No. 10,045,256 Issued |
| 2018-08-21 | U.S. Patent No. 10,057,095 Issued |
| 2018-09-11 | U.S. Patent No. 10,075,946 Issued |
| 2018-09-18 | U.S. Patent No. 10,080,204 Issued |
| 2018-10-02 | U.S. Patent No. 10,090,894 Issued |
| 2019-03-12 | U.S. Patent No. 10,231,211 Issued |
| 2019-03-22 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 10,009,884 - "Method of error recovery in transmitting and receiving voice service in packet based mobile communication systems"
The Invention Explained
- Problem Addressed: The patent describes the challenge of recovering from transmission errors in packet-based mobile systems (like VoLTE) that use "persistent allocation" schemes to support voice services. In such schemes, a control message error can disrupt the entire persistent data flow, degrading quality ('884 Patent, col. 1:22-34).
- The Patented Solution: The invention proposes a method for a base station to recover from errors by retransmitting control information when an acknowledgement (ACK) message is not received from the mobile terminal. This ensures that control messages, such as those activating or deactivating a persistent resource allocation, are properly received, allowing the system to quickly recover from the error and maintain communication quality ('884 Patent, Abstract; col. 2:7-12).
- Technical Importance: This error recovery mechanism is important for maintaining the quality of real-time services like voice-over-LTE, where persistent scheduling is used to reduce control channel overhead but is vulnerable to transmission errors ('884 Patent, col. 1:26-31).
Key Claims at a Glance
- The complaint asserts independent claims 13, 19, and 25 (Compl. ¶304). The lead independent claim analyzed here is claim 19, a communication method performed by a base station.
- Essential elements of claim 19 include:
- transmitting a first message on a first Physical Downlink Control Channel (PDCCH) in a first subframe, the first message indicating an activation of a semi-persistent scheduling and comprising first information;
- transmitting first data on a first Physical Downlink Shared Channel (PDSCH) based on the first information;
- transmitting second data on a second PDSCH in a second subframe based on the first information;
- transmitting a second message on a second PDCCH in a third subframe, the second message indicating a release of the semi-persistent scheduling; and
- retransmitting the second message if an acknowledgement (ACK) from the mobile terminal is not received.
U.S. Patent No. 10,045,256 - "Method for transmitting data frame in wireless local area network and apparatus for the same"
The Invention Explained
- Problem Addressed: The patent addresses the need for new methods to structure and transmit data frames in next-generation, Very High Throughput (VHT) wireless local area networks (WLANs), such as those compliant with the IEEE 802.11ac standard ('256 Patent, col. 1:47-54).
- The Patented Solution: The invention defines a method for generating and transmitting a data frame that includes a special "service field" and a "VHT-SIG-B" field. The entire data field is scrambled using a sequence derived from an initial scrambling sequence and a generator polynomial. The contents of the service field itself are determined by a set of "TXVECTOR" parameters, which provides control information for how the field is structured ('256 Patent, Abstract; col. 2:20-31). This structure allows for the high-speed, flexible data transmission required by modern Wi-Fi standards.
- Technical Importance: This method provides a foundational element of the physical layer protocol for VHT systems (e.g., 802.11ac), enabling the high data rates that support modern wireless internet applications by specifying how data frames are structured, scrambled, and controlled ('256 Patent, col. 1:55-59).
Key Claims at a Glance
- The complaint asserts independent claims 1, 7, 12, and 17 (Compl. ¶441). The lead independent claim analyzed here is claim 1, a method for transmitting a data frame.
- Essential elements of claim 1 include:
- transmitting, by a wireless device, a data frame via an operating channel bandwidth;
- wherein the data frame includes a data field having a service field and a very high throughput signal information (VHT-SIG-B) field;
- wherein the data field is scrambled with a scrambling sequence;
- wherein the scrambling sequence is generated based on an initial scrambling sequence and a generator polynomial; and
- wherein the service field is determined based on a set of TXVECTOR parameters including control information for the service field.
Multi-Patent Capsule: U.S. Patent No. 9,603,174
- Patent Identification: U.S. Patent No. 9,603,174, "Error control method, medium access control (MAC) frame designing method, and terminal registration method in wireless communication system, and recording medium," issued March 21, 2017.
- Technology Synopsis: The patent relates to methods for a base station to transmit, or a terminal to receive, a subframe based on an identifier associated with the terminal (Compl. ¶49).
- Asserted Claims: Claims 9 and 25 are asserted (Compl. ¶49).
- Accused Features: AT&T's LTE mobile network and all accused devices configured to transmit or receive subframes in accordance with LTE Release 8 (or later) are accused of infringement (Compl. ¶¶49-50).
Multi-Patent Capsule: U.S. Patent No. 8,761,814
- Patent Identification: U.S. Patent No. 8,761,814, "Method for paging information in cellular system," issued June 24, 2014.
- Technology Synopsis: The patent relates to methods for a base station to transmit, or a terminal to receive, paging information in a cellular system (Compl. ¶66).
- Asserted Claims: Claims 1 and 10 are asserted (Compl. ¶66).
- Accused Features: AT&T's LTE mobile network and all accused devices configured to generate or decode paging information in accordance with LTE Release 8 (or later) are accused of infringement (Compl. ¶¶66-67).
III. The Accused Instrumentality
Product Identification
The accused instrumentalities are broadly defined as (1) AT&T's mobile network, including all base station equipment, and (2) all mobile devices ("Accused Usage Devices" and "Accused Sale Devices") sold by or used on AT&T's network that are configured to operate in accordance with 4G LTE, LTE-Advanced (LTE-A), and/or Wi-Fi (IEEE 802.11) standards (Compl. ¶¶ 23, 50, 67, 305, 340).
Functionality and Market Context
The complaint alleges that AT&T operates a nationwide 4G LTE network covering over 325 million people (Compl. ¶24). It further alleges that substantial portions of this network are upgraded to LTE-Advanced, which offers speeds 50% faster than standard 4G LTE, and that AT&T markets and sells numerous mobile devices specifically for use on this LTE and LTE-A network (Compl. ¶¶ 25-26). The complaint also identifies AT&T's system of Wi-Fi hotspots (the "AT&T Hotspot System") and devices that communicate using Wi-Fi standards such as IEEE 802.11ac as accused instrumentalities (Compl. ¶¶ 28, 31, 340). The core accused functionality is the standards-compliant operation of this network infrastructure and the associated mobile devices. No probative visual evidence provided in complaint.
IV. Analysis of Infringement Allegations
U.S. Patent No. 10,009,884 - Infringement Allegations
| Claim Element (from Independent Claim 19) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| transmitting a first message to a mobile terminal on a first Physical Downlink Control Channel (PDCCH) in a first subframe, wherein the first message indicates an activation of a semi-persistent scheduling and the first message comprises first information | AT&T's LTE Release 8 (and later) compliant base stations are alleged to perform semi-persistent scheduling for services such as voice, which requires transmitting an activation message on the PDCCH. | ¶¶304, 305, 308 | col. 9:55-60 |
| transmitting first data to the mobile terminal on a first Physical Downlink Shared Channel (PDSCH) in the first subframe based on the first information | Following the activation message, AT&T's base stations are alleged to transmit data packets (e.g., for voice) on the PDSCH according to the allocated semi-persistent schedule. | ¶¶304, 305, 308 | col. 9:61-64 |
| transmitting a second message to the mobile terminal on a second PDCCH in a third subframe, the second message indicating a release of the semi-persistent scheduling | AT&T's base stations are alleged to transmit a release or deactivation message on the PDCCH to terminate the semi-persistent resource allocation. | ¶¶304, 305, 308 | col. 11:21-25 |
| retransmitting the second message to the mobile terminal if an acknowledgement (ACK) is not received from the mobile terminal... | The complaint alleges that AT&T's network practices the claimed method of error recovery, which includes retransmitting the release message upon failure to receive an ACK. | ¶¶304, 305 | col. 10:1-5 |
Identified Points of Contention
- Scope Questions: The complaint's theory rests on the patent's alleged essentiality to the LTE standard (Compl. ¶304). A central question will be whether claim 19, particularly the final element requiring retransmission of a release message, describes a mandatory part of the LTE standard as implemented by AT&T, or an optional or alternative error-recovery method.
- Technical Questions: What evidence does the complaint provide that AT&T's network specifically performs the error recovery step of retransmitting the deactivation message upon a failure to receive an ACK, as required by the claim, versus other potential error recovery procedures?
U.S. Patent No. 10,045,256 - Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| transmitting, by a wireless device, a data frame via an operating channel bandwidth | Accused Wi-Fi devices and access points are alleged to transmit data frames in accordance with the IEEE 802.11ac standard. | ¶¶441, 442, 444 | col. 2:25-27 |
| wherein the data frame includes a data field having a service field and a very high throughput signal information (VHT-SIG-B) field | The 802.11ac standard allegedly requires the use of data frames containing the claimed VHT-SIG-B and service fields. | ¶¶441, 444 | col. 2:27-31 |
| wherein the data field is scrambled with a scrambling sequence | Data scrambling is a standard part of Wi-Fi communication protocols, which the accused products are alleged to perform. | ¶¶441, 442 | col. 2:27-28 |
| wherein the service field is determined based on a set of TXVECTOR parameters including control information for the service field | The complaint alleges that the accused 802.11ac-compliant devices determine the service field based on TXVECTOR parameters as required by the standard and the patent. | ¶¶441, 444 | col. 2:28-31 |
Identified Points of Contention
- Scope Questions: The dispute may focus on whether AT&T's implementation of the 802.11ac standard necessarily practices the specific method of determining the "service field" based on the claimed "TXVECTOR parameters." Does the standard allow for alternative methods not covered by the claim?
- Technical Questions: What evidence demonstrates that the accused products' "service field" is determined by the specific "set of TXVECTOR parameters" that includes "control information for the service field," as recited in the claim, rather than by a different set of control parameters?
V. Key Claim Terms for Construction
U.S. Patent No. 10,009,884
- The Term: "retransmit the second message if the processor fails to receive an acknowledgement (ACK) from a mobile terminal acknowledging receipt of the second message" (Claim 19).
- Context and Importance: This term defines the specific error-recovery step that is central to the invention. The infringement analysis will depend on whether AT&T's network performs this exact recovery step, as opposed to other potential error-handling mechanisms. Practitioners may focus on this term because it appears to be the core novel element of the claim.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent abstract describes the invention broadly as a method where "the base station may retransmit the control information" when an error occurs, which could suggest the specific trigger (no ACK) is just one example ('884 Patent, Abstract).
- Evidence for a Narrower Interpretation: The claim language is highly specific, requiring retransmission only of the second message (the release message) and only upon the specific condition of failing to receive an ACK for that second message. The detailed description and figures also focus on this precise scenario ('884 Patent, FIG. 2; col. 9:48-52).
U.S. Patent No. 10,045,256
- The Term: "service field is determined based on a set of TXVECTOR parameters including control information for the service field" (Claim 1).
- Context and Importance: The infringement analysis hinges on whether the accused devices generate the "service field" in the precise manner claimed. The definition of "TXVECTOR parameters" and their relationship to the "service field" will be critical.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification generally describes the invention as providing a "method for transmitting a data frame" for a VHT WLAN system, which might support a broader reading of the specific control mechanisms as exemplary ('256 Patent, col. 2:12-15).
- Evidence for a Narrower Interpretation: The patent provides a detailed structure for the service field, specifying that it "may include a the scrambler initialization, a reserved field and a cyclic redundancy check" ('256 Patent, col. 3:5-7). Table 4 further specifies the "service field information parameter" within the TXVECTOR, linking the two explicitly and narrowly ('256 Patent, Table 4). This suggests a specific, limited definition.
VI. Other Allegations
Indirect Infringement
The complaint alleges both induced and contributory infringement for all asserted patents. Inducement is based on allegations that AT&T encourages and instructs its customers to use its network and compatible devices in an infringing manner, knowing of the patents (Compl. ¶¶ 53-55, 309-311). Contributory infringement is based on allegations that the accused devices are especially designed to operate on the LTE and Wi-Fi networks and have no substantial non-infringing use (Compl. ¶¶ 57-59, 313-315).
Willful Infringement
Willfulness is alleged for all patents based on pre-suit knowledge. The complaint alleges that AT&T had knowledge of the patent families since at least May and June 2015 via notice letters, as well as knowledge through ETRI's declarations of the patents as essential to the LTE and Wi-Fi standards (Compl. ¶¶ 61, 317, 351).
VII. Analyst’s Conclusion: Key Questions for the Case
- A central issue will be one of claim scope versus standard essentiality: For each of the twenty-seven asserted patents, does the claim language, when properly construed, read on a mandatory, non-optional component of the relevant LTE or Wi-Fi standard as implemented by AT&T, or does it cover an optional feature or one of several alternative implementations that AT&T may not use?
- A key evidentiary question will be one of proof of operation: Beyond alleging standards-compliance, what specific technical evidence will be presented to demonstrate that AT&T's network equipment and the accused mobile devices actually perform the specific, multi-step methods recited in the asserted independent claims across this large and diverse patent portfolio?
- Given the patents' alleged standard-essential status, a significant legal question will involve the role of FRAND licensing obligations: How will the original patent owner's commitment to license essential patents on Fair, Reasonable, and Non-Discriminatory terms affect the Plaintiff's claims for damages and injunctive relief, should infringement be established?