DCT

1:18-cv-01847

NEC Corp v. Xtera Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:18-cv-01847, D. Del., 11/21/2018
  • Venue Allegations: Venue is alleged as proper in the District of Delaware on the basis that both Defendants are Delaware corporations and are therefore residents of the district.
  • Core Dispute: Plaintiff alleges that Defendants’ submarine telecommunication systems and components infringe four patents related to optical signal amplification, multiplexing, fault compensation, and coherent reception.
  • Technical Context: The technology at issue relates to high-capacity, long-haul submarine fiber optic cable systems, which are critical infrastructure for global data and internet traffic.
  • Key Procedural History: The complaint notes a related investigation before the International Trade Commission, Certain Subsea Telecommunications Systems and Components Thereof, Inv. No. 337-TA-1098, suggesting a parallel legal strategy.

Case Timeline

Date Event
2000-08-02 Priority Date for U.S. Patent No. 6,941,075
2001-10-09 Priority Date for U.S. Patent No. 6,739,727
2004-05-25 Issue Date for U.S. Patent No. 6,739,727
2005-09-06 Issue Date for U.S. Patent No. 6,941,075
2009-03-19 Priority Date for U.S. Patent No. 8,798,473
2010-05-21 Priority Date for U.S. Patent No. 9,246,599
2014-08-05 Issue Date for U.S. Patent No. 8,798,473
2016-01-26 Issue Date for U.S. Patent No. 9,246,599
2018-11-21 Complaint Filing Date

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

U.S. Patent No. 6,739,727 - "Raman Amplifier and Pumping Apparatus, and Program," Issued May 25, 2004

The Invention Explained

  • Problem Addressed: When using Raman amplification to boost optical signals over long distances, the high-power "pumping lights" can interact with each other through a nonlinear effect called Four-Wave Mixing (FWM). This interaction can generate unwanted lightwaves (noise) that fall within the same wavelength band as the data signal, corrupting the signal quality ('727 Patent, col. 3:34-45).
  • The Patented Solution: The invention proposes a method for carefully selecting the wavelengths of the pumping lights. It specifies a mathematical relationship between the pumping light wavelengths and the signal light's wavelength band, designed to ensure that any interfering lightwaves created by FWM are generated outside of the signal band, thereby preventing signal degradation ('727 Patent, Abstract; col. 4:3-14).
  • Technical Importance: This technique allows for the use of powerful Raman amplification to extend transmission distances without the typical signal degradation caused by FWM, a significant issue for high-performance optical systems ('727 Patent, col. 3:46-51).

Key Claims at a Glance

  • The complaint asserts independent claim 1 (Compl. ¶25).
  • Essential elements of claim 1:
    • A Raman amplification medium which provides signal lights with gain through the stimulated Raman effect;
    • a pumping means for injecting pumping lights of a plurality of wavelengths in this Raman amplification medium; and
    • a means for allocating wavelengths of said pumping lights so that the peak wavelengths of any two pumping lights (λmin, λmax) are in a specific mathematical relationship with the shortest (λshort) and longest (λlong) wavelengths of the signal light band, expressed as "λshort > λmin × λmax/(2λmin - λmax)" or "λmin × λmax/(2λmin - λmax) > λlong".
  • The complaint also asserts claims 2–4, 7–16, and 21–25 (Compl. ¶24).

U.S. Patent No. 6,941,075 - "Wavelength Division Multiplexing Optical Transmission Method and System," Issued September 6, 2005

The Invention Explained

  • Problem Addressed: In Wavelength Division Multiplexing (WDM) systems, optical amplifiers are typically optimized for a full load of channels. When some channels are inactive, the total optical power decreases, which can alter the gain characteristics of the amplifiers and degrade the performance of the active channels ('075 Patent, col. 1:56-64).
  • The Patented Solution: The patent describes a method of grouping signal channels and monitoring them. If one or more channels in a group become inactive, the system transmits a "control light" (a dummy signal) with a power level equal to the combined power of the missing signals. This maintains a constant total power level for the group, ensuring stable amplifier performance regardless of the number of active channels ('075 Patent, Abstract; col. 4:42-45).
  • Technical Importance: This approach enables flexible, on-demand use of channel capacity in WDM systems without negatively impacting the transmission quality of existing, active channels ('075 Patent, col. 2:14-18).

Key Claims at a Glance

  • The complaint asserts independent claim 1 (Compl. ¶42).
  • Essential elements of claim 1:
    • grouping transmittable n input signal light channels into groups each having x channels; and
    • for each group, whenever one or more of said x input channels does not currently include an input signal to be transmitted;
    • transmitting a control light having a same power level as a total power of signal lights of said one or more missing input signals.
  • The complaint also asserts claims 2–16 (Compl. ¶41).

U.S. Patent No. 8,798,473 - "Optical Signal Level Adjustment System, Information Analysis/Control Signal Generation Apparatus in the Same System, and Information Analysis/Control Signal Generation Method," Issued August 5, 2014

  • Patent Identification: U.S. Patent No. 8,798,473, "Optical Signal Level Adjustment System, Information Analysis/Control Signal Generation Apparatus in the Same System, and Information Analysis/Control Signal Generation Method," Issued August 5, 2014 (Compl. ¶14).
  • Technology Synopsis: The patent addresses the problem of increased power in remaining channels when a fault (like a cable cut) causes other signal channels to drop out in a submarine system. The invention describes a method for detecting a "fault pattern," determining the location of the fault, and transmitting a control signal to adjust the intensity of a "dummy light" to compensate for the lost channels, thereby preventing signal degradation from nonlinear effects ('473 Patent, Abstract).
  • Asserted Claims: Independent claim 1 is asserted (Compl. ¶60); claims 2-18 are also asserted (Compl. ¶59).
  • Accused Features: The accused Flexible Gateway Family allegedly infringes by detecting faults or disconnections, determining which channels are missing, and inserting "loading channels" to compensate if power levels drop or a terminal fails (Compl. ¶¶61-62).

U.S. Patent No. 9,246,599 - "Coherent optical receiver, apparatus and method for detecting interchannel skew in coherent optical receiver," Issued January 26, 2016

  • Patent Identification: U.S. Patent No. 9,246,599, "Coherent optical receiver, apparatus and method for detecting interchannel skew in coherent optical receiver," Issued January 26, 2016 (Compl. ¶15).
  • Technology Synopsis: In complex coherent optical receivers, signals are split into multiple components that travel through different electronic paths. Minor differences in path lengths can create a timing mismatch known as "skew," which can corrupt the final signal. The invention discloses a digital signal processing (DSP) unit that uses a Fast Fourier Transform (FFT) process to calculate this skew and a compensation unit to correct the delay, ensuring proper signal demodulation ('599 Patent, Abstract).
  • Asserted Claims: Independent claim 1 and claim 13 are asserted (Compl. ¶77).
  • Accused Features: The accused Nu-wave Optima platform allegedly includes a coherent optical receiver with a DSP that performs an FFT and includes a "skew compensation unit for compensating a difference in propagation delay" between signal components (Compl. ¶¶79, 82).

III. The Accused Instrumentality

Product Identification

The complaint names Xtera’s Nu-wave Optima, Flexible Gateway Family (which includes the "Open System Gateway" and "Virtual Fibre Gateway"), and related components and modules (Compl. ¶18).

Functionality and Market Context

  • The Nu-wave Optima is identified as Xtera's Submarine Line Terminal Equipment (SLTE) for long-haul submarine applications. Its alleged technical functions include providing a Dense Wavelength Division Multiplexing (DWDM) optical transport solution, supporting modulation types like QPSK and 16QAM, and enabling coherent detection and Raman amplification (Compl. ¶19).
  • The Flexible Gateway Family products are described as "open systems" that allow customers to connect third-party equipment and share capacity on fiber-optic cables. Their alleged functions include multiplexing/demultiplexing signals, optical channel monitoring (OCHM), and line monitoring (LME) (Compl. ¶20). The complaint alleges these products are used in submarine telecommunication systems offered by Xtera (Compl. ¶17). A diagram from an Xtera datasheet shows these systems handling missing traffic by adding "loading" signals (Compl. p. 14, Ex. O at 3).

IV. Analysis of Infringement Allegations

’727 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
A Raman amplification medium which provides signal lights with gain through the stimulated Raman effect; The accused Nu-wave Optima platform provides for "Extended reach through Raman amplification" in submarine systems, which use optical fiber as the medium. ¶26 col. 8:44-48
a pumping means for injecting pumping lights of a plurality of wavelengths in this Raman amplification medium; The Nu-wave Optima includes "Distributed Raman Pumps" that use "five pump wavelengths distributed in the spectral range between 1420 and 1500 nm." A product image shows the pump module. ¶27; p. 8 col. 8:46-48
a means for allocating wavelengths of said pumping lights so that... the peak wavelength λmin, of pumping light having the shorter wavelength and the peak wavelength λmax, of pumping light having the longer wavelength are in a relationship to the shortest wavelength... λshort and the longest wavelength... λlong... expressed as λshort>λmin×λmax/(2λmin−λmax) or λmin×λmax/(2λmin−λmax)>λlong. On information and belief, the Nu-wave Optima is used with signal lights having a shortest wavelength (λshort) of 1563.05nm. When using pump wavelengths of 1420nm (λmin) and 1480nm (λmax), the system allegedly satisfies the claimed relationship, as "1563.05nm > 1545.29 nm". ¶¶28-29 col. 8:50-64

Identified Points of Contention

  • Scope Questions: Claim 1 recites a "means for allocating wavelengths." The infringement analysis may turn on whether this requires an active, dynamic allocation controller as described in the patent's embodiments ('727 Patent, Fig. 1), or if it can be read on a system that is merely sold with or used in a static configuration that happens to satisfy the claimed mathematical formula.
  • Technical Questions: The complaint's infringement calculation relies on an "information and belief" allegation for the specific "λshort" of the signal light (1563.05nm) (Compl. ¶28). A central question will be what evidence supports that the accused products are actually used with these specific wavelengths, and whether infringement occurs across other standard operating configurations.

’075 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
grouping transmittable n ... input signal light channels into groups each having x channels ... The accused Flexible Gateway Family is alleged to group input signal light channels into multiple bands, such as "Band A, Band B, and Band C," as illustrated in a system diagram. ¶44; p. 14 col. 4:18-21
for each group, whenever one or more of said x input channels does not currently include an input signal to be transmitted in said channel, The system is alleged to detect when traffic signals are not present in a band. A provided diagram explicitly illustrates a state of "missing traffic" for one of the bands. ¶44; p. 14 col. 4:26-28
transmitting a control light having a same power level as a total power of signal lights of said one or more missing input signals. The accused system allegedly includes an "Optical Channel Monitor (OCHM)" that "monitors the overall spectrum and can add extra loading signals as needed." A diagram shows "Loading to handle missing traffic," which the complaint alleges is the claimed control light. The complaint alleges this loading meets the power-matching requirement. A diagram from Xtera illustrates a "Terminal fails" scenario where missing channels in a "Fault" state are replaced by "Loading" signals. ¶44; p. 21 col. 4:42-45

Identified Points of Contention

  • Scope Questions: The claim requires a "control light having a same power level as a total power of... missing input signals." The dispute may center on the required precision of this limitation. Does the accused OCHM's "loading signal" function meet this specific power-matching requirement, or does it provide a more generic, non-calculated power fill that does not meet the claim language?
  • Technical Questions: What evidence does the complaint provide that the accused OCHM actually calculates the precise power of missing signals before generating a corresponding control light? The functionality is described at a high level, and the question remains whether the accused product's operation technically matches the method claimed in the patent.

V. Key Claim Terms for Construction

Patent: '727 Patent

  • The Term: "means for allocating wavelengths" (from Claim 1)
  • Context and Importance: This term is in means-plus-function format under 35 U.S.C. § 112(f). Its construction will be limited to the corresponding structure described in the specification and its equivalents. Practitioners may focus on this term because the infringement case depends on whether the accused product's static configuration or specific use-case can be considered the claimed "means," or if it must contain the specific controller and logic shown in the patent.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: A party could argue the key structure is the "wavelength allocation controller (10)" shown in the figures, which is described as performing the function of allocating wavelengths to satisfy the claimed mathematical condition ('727 Patent, col. 8:50-53). This might be argued to cover any controller that achieves this result.
    • Evidence for a Narrower Interpretation: A party could argue the structure is limited to the specific implementation detailed in the specification, such as the controller (10) executing the steps of the flowchart in FIG. 6, which includes defining a wavelength band, allocating pumping light, and then explicitly checking if FWM light falls within the signal band ('727 Patent, col. 11:26-42).

Patent: '075 Patent

  • The Term: "same power level" (from Claim 1)
  • Context and Importance: The viability of the infringement allegation for the '075 patent hinges on this term. If "same" is construed to require mathematical identity, proof of infringement could be difficult. If it is construed to mean "substantially the same" or functionally equivalent for the purpose of stabilizing amplifier gain, the infringement case may be stronger.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The patent's objective is to solve the problem of gain variation in EDFAs ('075 Patent, col. 1:56-64). A party might argue that one of ordinary skill would understand "same power level" in this context to mean a power level sufficient to achieve the stated goal of keeping the total output level flat, not necessarily a bit-for-bit identical power value.
    • Evidence for a Narrower Interpretation: The claim language is precise. The specification states that "the total level of the control light J1 and the wavelength multiplexed light F1 at this time are equal to the total level of the signal lights E1 to E4" ('075 Patent, col. 4:42-45). This language suggests a direct equality, supporting a narrower construction requiring a calculated, one-to-one power replacement.

VI. Other Allegations

Indirect Infringement

The complaint alleges induced infringement for all four patents. The allegations are based on Defendants encouraging and instructing customers and end users through "manuals, white papers, training, and/or other technical support" to use the Accused Products in a manner that directly infringes (Compl. ¶¶32, 50, 68, 86).

Willful Infringement

Willfulness is alleged for all four patents. The complaint primarily bases this on post-suit knowledge, stating that Defendants had "actual knowledge and notice of the... patent and their infringement since at least as early as the service of this Complaint" (Compl. ¶¶29, 47, 65, 83). It also alleges that Defendants, as competitors, knew or should have known of NEC's patents due to NEC's status as a "pioneer" in the field (Compl. ¶36).

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

  • A central issue will be one of operational infringement: For the '727 and '599 patents, infringement appears to depend on specific operating parameters and internal software functions of the accused Nu-wave Optima. A key question is whether the evidence will show that the products' fundamental design and standard operation meet the claim limitations, or if infringement only occurs under specific, optional configurations alleged "on information and belief."
  • A second core issue is one of functional precision: For the '075 and '473 patents, which claim systems that compensate for missing signals with "dummy" or "control" light, the dispute will likely focus on whether the accused "loading" signals perform the precise functions claimed. Does the accused system merely add bulk power when a drop is detected, or does it perform the specific claimed functions of calculating and transmitting a light with the "same power level" as the missing signals ('075 patent) or executing a specific fault-pattern analysis to determine the adjustment amount ('473 patent)?
  • A key evidentiary question will be the substantiation of the highly technical allegations. The complaint provides block diagrams from the defendants' marketing materials, such as a diagram of a digital coherent receiver (Compl. p. 28), but the case will depend on discovery to reveal whether the internal workings of the accused DSPs, controllers, and software align with the detailed functional steps required by the asserted claims.