DCT

3:17-cv-02805

Cellular Communications Equipment LLC v. ZTE Corp

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 3:17-cv-02805, N.D. Tex., 10/12/2017
  • Venue Allegations: Plaintiff alleges venue is proper because Defendants have committed acts of infringement in the district and maintain regular and established places of business there.
  • Core Dispute: Plaintiff alleges that Defendants’ mobile devices, which comply with cellular communication standards such as LTE and UMTS, infringe three patents related to emergency call procedures, carrier aggregation signaling, and data retransmission methods.
  • Technical Context: The patents address foundational technologies for modern mobile communications, including efficient emergency call handling over IP networks, reliable signaling for combining multiple frequency bands (carrier aggregation), and robust data transmission protocols.
  • Key Procedural History: The complaint alleges Defendants had pre-suit knowledge of the patents-in-suit from prior litigation where the patents were asserted against some of the current carrier Defendants. Notably, after the filing of this complaint, all asserted claims of U.S. Patent No. 8,902,770 were cancelled in an inter partes review (IPR) proceeding (IPR2018-00091), a fact which may be dispositive for infringement allegations related to that patent.

Case Timeline

Date Event
2004-09-15 ’786 Patent Priority Date
2006-04-27 ’872 Patent Priority Date
2010-09-28 ’770 Patent Priority Date
2012-08-28 ’872 Patent Issued
2014-02-04 ’786 Patent Issued
2014-12-02 ’770 Patent Issued
2017-10-12 Complaint Filing Date
2017-10-26 IPR Filed Against ’770 Patent (IPR2018-00091)
2020-05-26 IPR Certificate Issued Cancelling All Claims of ’770 Patent

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 8,254,872 - “Simplified Method for IMS Registration in the Event of Emergency Calls,” issued August 28, 2012

The Invention Explained

  • Problem Addressed: Standard procedures for making emergency calls over an IP Multimedia Subsystem (IMS) require a special, time-consuming registration process. This delay is particularly undesirable in emergency situations and can be complicated when a user is roaming outside their home network. (’872 Patent, col. 1:13-56).
  • The Patented Solution: The patent discloses a method to bypass this special registration. If a mobile terminal is already registered with the IMS, it compares the network identifier of its current (visited) network with its stored home network identifier. If they match (i.e., the user is not roaming), the terminal can set up the emergency call immediately, dispensing with the separate emergency registration step and thereby saving critical time. (’872 Patent, Abstract; col. 2:28-39).
  • Technical Importance: The method accelerates the connection of emergency calls made over modern IP-based cellular networks, a critical feature for user safety. (’872 Patent, col. 2:57-63).

Key Claims at a Glance

  • The complaint asserts independent claims 1 (method) and 12/13 (apparatus), along with several dependent claims (Compl. ¶21).
  • The essential elements of independent claim 1 include:
    • Receiving, at a terminal, a network identifier of a visited network.
    • Comparing the received network identifier with a network identifier of the terminal's home network.
    • Setting up an emergency call connection while dispensing with a special IMS registration for that call, conditioned on the terminal already being registered in the IMS and the network identifiers matching.
  • The complaint reserves the right to assert additional claims (Compl. ¶21).

U.S. Patent No. 8,902,770 - “Carrier Indicator Field Usage and Configuration in Carrier Aggregation,” issued December 2, 2014

The Invention Explained

  • Problem Addressed: In LTE-Advanced networks, carrier aggregation allows a device to use multiple frequency bands (component carriers) simultaneously. When the network schedules data, it may need to use a Carrier Indicator Field (CIF) to tell the device which carrier the data is for. A problem arises when a device's configuration changes (e.g., from a single carrier to multiple carriers), as both the device and the network must be synchronized on whether the control signaling includes a CIF to prevent misinterpretation of commands. (’770 Patent, col. 2:34-51).
  • The Patented Solution: The invention provides a method to manage the format of the downlink control channel (PDCCH) in coordination with switching the device between being enabled or disabled for cross-carrier scheduling. The patent describes using explicit signaling (e.g., an RRC Connection Reconfiguration message) from the network to inform the device of the format change, ensuring both parties use the same signaling rules (e.g., with or without a CIF). (’770 Patent, Abstract; FIG. 7; col. 4:43-54).
  • Technical Importance: This technology ensures reliable and unambiguous control signaling in LTE networks that use carrier aggregation, which is essential for achieving higher data rates and managing network resources efficiently. (’770 Patent, col. 2:50-51).

Key Claims at a Glance

  • The complaint asserts independent claims 1 (method) and 10 (apparatus), among others (Compl. ¶37). All asserted claims (1-24) were subsequently cancelled via inter partes review (IPR2018-00091).
  • The essential elements of independent claim 1 include:
    • Changing the format of a downlink control channel in conjunction with switching the user equipment between being enabled and disabled for cross-carrier scheduling.
    • Basing the format change on explicit signaling between the network and the user equipment.
    • Thereafter using the changed format on at least one serving cell.
  • The complaint reserves the right to assert additional claims (Compl. ¶37).

Multi-Patent Capsule: U.S. Patent No. 8,645,786 - “Decoding Method,” issued February 4, 2014

  • Technology Synopsis: This patent addresses error recovery in wireless communications using Hybrid Automatic Repeat reQuest (HARQ). The invention specifies a method for retransmitting data packets by selecting different "redundancy versions" (i.e., differently encoded representations of the same information) based on the coding rate. This allows the system to choose between self-decodable versions and other versions to optimize decoding success upon retransmission. (’786 Patent, Abstract; col. 4:50-65).
  • Asserted Claims: Independent claims 1 (method) and 13 (apparatus), and dependent claims 2-5, 8, and 12 (Compl. ¶54).
  • Accused Features: The complaint accuses ZTE devices that operate in a UMTS network environment using FDD enhanced uplink of infringement. These devices are alleged to be configured to select redundancy versions for retransmission based on coding rate, as claimed in the patent. (Compl. ¶54, ¶56).

III. The Accused Instrumentality

Product Identification

  • The complaint identifies numerous ZTE-manufactured mobile devices, including smartphones, tablets, and mobile hotspots, that are distributed by U.S. carriers including AT&T, T-Mobile, Verizon, and Sprint (Compl. ¶21, ¶37, ¶54). The devices are collectively referred to as the "'872 ZTE Devices," "'770 ZTE Devices," and "'786 ZTE Devices," depending on the patent being asserted (Compl. ¶21, ¶37, ¶54).

Functionality and Market Context

  • The complaint alleges that the accused devices implement functionality required by modern 3GPP cellular standards. For the ’872 patent, the key functionality is supporting Voice over LTE (VoLTE) and the associated emergency call procedures (Compl. ¶21, ¶23). For the ’770 patent, it is the support for LTE Carrier Aggregation (Compl. ¶37, ¶39). For the ’786 patent, it is the use of HARQ in UMTS networks with enhanced uplink (Compl. ¶54, ¶56). The complaint frames the accused features not as optional functionalities but as integral to the devices' operation on modern cellular networks.
  • No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

8,254,872 Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
receiving, at a terminal, a network identifier of a visited network, the network identifier of the visited network notified to the terminal when the terminal is registered in the visited network; Each '872 ZTE Device is configured to receive a network identifier (e.g., MCC, MNC, PLMN ID) of a visited network when it registers with that network, pursuant to 3GPP standards. ¶23 col. 2:22-26
comparing the received network identifier of the visited network with a network identifier of a home network of the terminal; and Each device is configured to compare the received network identifier with a stored home network identifier to determine if it is in its home network. ¶23 col. 2:30-34
setting up an emergency call connection, wherein an IP multimedia subsystem registration of the terminal...is dispensed with when the terminal is already registered...and the comparing reveals a match... Each device is configured to set up an emergency call connection without performing a special IMS registration if it is already registered and the comparison shows the visited and home networks are identical. ¶23, ¶29 col. 2:28-39
  • Identified Points of Contention:
    • Scope Questions: A central question may be whether the term "network identifier" as defined and used in the patent is coextensive with the various identifiers specified in the 3GPP standards cited by the complaint (e.g., MCC, MNC, GUTI, PLMN ID). The defense may argue for a narrower construction limited to the specific examples in the specification, such as MCC/MNC.
    • Technical Questions: The complaint alleges the devices are "configured to" perform the claimed steps by citing to broad 3GPP technical specifications. A key evidentiary question will be whether the plaintiff can prove that the accused devices' software and hardware actually execute the specific comparison and conditional logic required by the claim, as opposed to merely being capable of operating on a network where such logic could be implemented.

8,902,770 Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
changing format of a downlink control channel for a user equipment in conjunction with switching the user equipment between being enabled for cross carrier scheduling and being disabled for cross carrier scheduling... Each '770 ZTE Device is configured to change the format of its downlink control channel (PDCCH) when it is switched between single-cell and multi-cell (cross-carrier scheduling) modes. ¶39 col. 4:43-48
in which changing the format of the downlink control channel is based on explicit signaling between a network and the user equipment; This format change is allegedly based on explicit signaling from the network, such as an RRC Connection Reconfiguration message as defined in 3GPP standards. ¶39 col. 5:10-14
and thereafter using the changed format of the downlink control channel at least on one serving cell of the user equipment's configured set of component carriers. The device then allegedly uses the newly adopted PDCCH format (e.g., with or without a Carrier Indicator Field) on at least one of its configured serving cells. ¶39 col. 4:48-51
  • Identified Points of Contention:
    • Legal Questions: The primary issue for the ’770 patent is its viability. As all asserted claims were cancelled in IPR2018-00091, the infringement allegations are likely moot. Any further analysis is academic, pending a successful appeal of the IPR decision.
    • Scope Questions: If the patent were valid, a likely dispute would center on the term "explicit signaling". The question would be whether an RRC message that reconfigures a device's cell list—which may indirectly trigger a format change—constitutes the direct, "explicit signaling" of a format change required by the claim.

V. Key Claim Terms for Construction

  • For the ’872 Patent:

    • The Term: "network identifier"
    • Context and Importance: The entire inventive concept of the ’872 patent hinges on a comparison of network identifiers. The definition of this term will determine whether the technical identifiers used in the accused devices (e.g., PLMN-ID, GUTI) meet the claim limitation. Practitioners may focus on this term because the patent's examples are specific (MCC/MNC), while the standard uses a variety of related identifiers.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The specification refers generally to "an identifier (network identifier) which identifies its home network," suggesting a functional definition could be argued. ( Compl. ¶19; ’872 Patent, col. 2:15-17).
      • Evidence for a Narrower Interpretation: The patent repeatedly uses "MCC/MNC (Mobile Country Code/Mobile Network Code)" as the primary, and often only, example of a network identifier, which may support a construction limited to that specific format. ( Compl. ¶19; ’872 Patent, col. 2:18-21; FIG. 1).

  • For the ’770 Patent:

    • The Term: "explicit signaling"
    • Context and Importance: This term is critical because claim 1 is limited to a format change based on "explicit signaling," distinguishing it from implicit methods. The viability of the infringement allegation would depend on proving that the accused RRC messages constitute this type of signal. This analysis is academic, given the cancellation of the claims.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The patent contrasts implicit rules with explicit instructions from the network, suggesting any direct message from the network that results in the format change could qualify as "explicit." ( Compl. ¶35; ’770 Patent, col. 5:10-24).
      • Evidence for a Narrower Interpretation: The specification’s embodiment describes a specific RRC Connection Reconfiguration message that contains the instruction, which could support an argument that the term is limited to a direct command within a specific message type. ( Compl. ¶35; ’770 Patent, col. 7:45-53).

VI. Other Allegations

  • Indirect Infringement: The complaint alleges both induced and contributory infringement for all three patents. The inducement claims are based on allegations that Defendants provide instructional materials (user manuals, support websites) that encourage end-users to operate the devices in an infringing manner (e.g., by making VoLTE calls or using carrier aggregation) (Compl. ¶27, ¶43, ¶60). The contributory infringement claims are based on allegations that the accused devices contain specific hardware, such as baseband processors, that are specially programmed to perform the patented methods and are not staple articles of commerce (Compl. ¶29, ¶45, ¶62).
  • Willful Infringement: The complaint alleges willful infringement based on pre-suit knowledge. The alleged sources of knowledge include Defendants' membership in standards bodies like 3GPP where patents are declared, as well as actual notice from prior lawsuits where Plaintiff asserted the same patents against several of the carrier Defendants. The complaint alleges ZTE was on notice of these suits by monitoring CCE's litigation activity. (Compl. ¶25, ¶41, ¶58, ¶71).

VII. Analyst’s Conclusion: Key Questions for the Case

  • A central procedural question is one of mootness: Given the post-filing cancellation of all asserted claims of the ’770 patent in an inter partes review, a threshold issue for the court will be to determine if any viable case remains with respect to that patent.
  • A core issue for the ’872 patent will be one of definitional scope: Can the term "network identifier," which the patent primarily exemplifies as an MCC/MNC pair, be construed broadly enough to read on the different but functionally related identifiers (e.g., PLMN-ID, GUTI) used in the accused LTE-compliant devices?
  • A key evidentiary challenge will be one of operational proof: For the remaining ’872 and ’786 patents, can the plaintiff progress beyond allegations based on 3GPP standards compliance and produce device-specific evidence demonstrating that the accused ZTE products actually execute the specific, multi-step logical processes recited in the asserted claims?