DCT

1:17-cv-01876

Xtera Inc v. Nokia Corp

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 1:17-cv-01876, D. Del., 12/29/2017
  • Venue Allegations: Venue for Defendant Nokia US LLC is alleged based on its incorporation in Delaware. Venue for the foreign-domiciled Nokia entities is alleged under 28 U.S.C. § 1391(c)(3) as non-U.S. residents.
  • Core Dispute: Plaintiff alleges that Defendant’s subsea optical networking systems, including its Photonic Service Engine 2 and 1620LM SLTE products, infringe six patents related to high-speed optical communication technologies.
  • Technical Context: The technology at issue involves subsea fiber-optic telecommunication systems, which form the backbone of global internet and data traffic by connecting terrestrial networks across oceans.
  • Key Procedural History: The complaint does not mention prior litigation or licensing history between the parties. However, subsequent to the complaint's filing, asserted claims of two patents-in-suit have been impacted by post-grant proceedings. Claims 13-20 of the ’798 patent were cancelled in Inter Partes Review No. IPR2018-01157. Claims 1-7 and 9-13 of the ’637 patent were disclaimed by the patent owner. The assertion of these specific claims may no longer be viable.

Case Timeline

Date Event
2002-04-12 ’171 Patent Priority Date
2003-04-17 ’403 Patent Priority Date
2005-07-25 ’331 Patent Priority Date
2007-10-16 ’798 Patent Priority Date
2008-05-27 ’637 Patent Priority Date
2009-04-07 ’331 Patent Issue Date
2009-10-27 ’068 Patent Priority Date
2010-12-28 ’403 Patent Issue Date
2013-01-08 ’798 Patent Issue Date
2013-02-19 ’068 Patent Issue Date
2013-03-26 ’637 Patent Issue Date
2015-03-03 ’171 Patent Issue Date
2017-12-29 Complaint Filing Date

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

U.S. Patent No. 8,380,068 - “Distinct Dispersion Compensation for Coherent Channels,” issued Feb. 19, 2013 (’068 Patent)

The Invention Explained

  • Problem Addressed: In long-haul optical systems that combine different types of signals, "coherent" channels (which allow for electronic dispersion compensation at the receiver) and "non-coherent" channels (which require optical dispersion compensation along the fiber link) have conflicting optimization needs (U.S. 8,380,068 Patent, col. 1:15-41, 6:8-13).
  • The Patented Solution: The invention is an optical assembly that physically separates a mixed signal into two groups: coherent channels and non-coherent channels. Each group is sent down a separate optical path, allowing a "dispersive element" to be applied differently to the non-coherent channels than to the coherent channels (which may receive no optical dispersion compensation at all). The two groups are then recombined into a single fiber for continued transmission (’068 Patent, Abstract; col. 2:55-67).
  • Technical Importance: This approach allows network operators to upgrade existing systems by adding high-capacity coherent channels alongside legacy non-coherent channels on the same fiber, while independently optimizing the physical link for each signal type (’068 Patent, col. 6:8-13).

Key Claims at a Glance

  • Independent claim 1 is asserted (Compl. ¶64).
  • The essential elements of claim 1 are:
    • An input optical port for receiving a mixed signal with both coherent and non-coherent channels.
    • An optical demultiplexer configured to separate the channels onto a coherent optical path and a non-coherent optical path.
    • A dispersive element that applies a different amount of dispersion to the non-coherent path than to the coherent path.
    • An optical multiplexer to recombine the channels from both paths into a mixed output signal.

U.S. Patent No. 7,860,403 - “Data Format for High Bit Rate WDM Transmission,” issued Dec. 28, 2010 (’403 Patent)

The Invention Explained

  • Problem Addressed: In high-speed Wavelength Division Multiplexed (WDM) systems, transmitting data using narrower optical pulses allows for higher bit rates but also creates a broader frequency spectrum for each channel, limiting how many channels can be packed into a fiber's available bandwidth (U.S. 7,860,403 Patent, col. 1:11-30).
  • The Patented Solution: The invention proposes a method of shaping data pulses to improve spectral efficiency. It involves generating a series of optical pulses, filtering them to produce "carrier pulses" that extend over more than one time slot, and then modulating them with data. The filtering process is designed to create a specific pulse shape with a temporal minimum located in the center of adjacent time slots, which mitigates the negative effects of pulse overlap (’403 Patent, Abstract; col. 1:49-62).
  • Technical Importance: This data format allows for greater spectral efficiency compared to conventional Return-to-Zero (RZ) and Non-Return-to-Zero (NRZ) formats, enabling more data channels to be transmitted over the same optical fiber (’403 Patent, col. 2:1-5).

Key Claims at a Glance

  • Independent claim 1 is asserted (Compl. ¶78).
  • The essential elements of method claim 1 are:
    • Generating a periodic series of optical pulses defining a series of time slots.
    • Filtering the pulses with a filter to produce carrier pulses extending over more than one time slot.
    • Modulating the pulses with data for transmission.
    • Wherein the filter gives rise to a carrier pulse having a temporal profile with a minimum substantially in the center of adjacent time slots and an oscillating tail extending from that minimum.

U.S. Patent No. 8,971,171 - “Reduced FEC Overhead in an Optical Transmission System,” issued Mar. 3, 2015 (’171 Patent)

  • Technology Synopsis: The patent addresses the bandwidth consumption of Forward Error Correction (FEC) overhead in optical systems (U.S. 8,971,171 Patent, col. 1:7-11). The proposed solution is a transmission system that encodes an information sequence with FEC and then uses a partitioner to split the encoded sequence into two parts: one part identical to the original information sequence and the other part equivalent to the coding overhead. These two parts are then transmitted as separate channels at a rate lower than the predetermined total rate, reducing the overhead burden on any single channel (Compl. ¶92).
  • Asserted Claims: Claim 1 (Compl. ¶93).
  • Accused Features: The complaint alleges that Nokia's products provide an FEC encoder and a partitioner that divides the encoded sequence into an information part and an overhead part for transmission on separate channels (Compl. ¶93).

U.S. Patent No. 8,351,798 - “Phase Shift Keyed High Speed Signaling,” issued Jan. 8, 2013 (’798 Patent)

  • Technology Synopsis: This patent describes a method for configuring long-haul optical systems to mitigate chromatic dispersion, a phenomenon that degrades signal quality over long distances (U.S. 8,351,798 Patent, col. 1:19-24). The invention involves adjusting a tunable pre-compensation mechanism at the transmit terminal so that the point of minimum accumulated dispersion for a majority of WDM channels occurs within a central region of the optical fiber link. This adjustment is performed using a closed control loop that measures the bit error rate at the receiver to achieve an acceptable level (Compl. ¶106).
  • Asserted Claims: Claim 13 (Compl. ¶107). Subsequent to the complaint filing, claims 13-20 were cancelled in Inter Partes Review IPR2018-01157.
  • Accused Features: The accused products are alleged to perform the claimed method by adjusting a tunable pre-compensation mechanism based on a closed control loop that measures the bit error rate (Compl. ¶107).

U.S. Patent No. 8,406,637 - “Automatic Pre-emphasis,” issued Mar. 26, 2013 (’637 Patent)

  • Technology Synopsis: The patent discloses a system for automatically managing the power levels ("pre-emphasis") of different channels in a WDM system to ensure signal quality (U.S. 8,406,637 Patent, col. 1:5-12). The system uses a central control processor to calculate a "desired value of a quality metric" (e.g., bit error rate) for each channel and transmits this value to the individual transmitters. Each transmitter then autonomously adjusts its own drive power until a measured quality metric equals the desired value, enabling distributed and responsive power control (Compl. ¶120).
  • Asserted Claims: Claim 1 (Compl. ¶121). Subsequent to the complaint filing, claims 1-7 and 9-13 were disclaimed.
  • Accused Features: Nokia's products are alleged to comprise a WDM transmitter with a control processor that calculates and transmits a desired quality metric, and a plurality of transmitters that each autonomously adjust their drive power to meet that metric (Compl. ¶121).

U.S. Patent No. 7,515,331 - “Twin Optical Amplifier with Dual Pump Power Control,” issued Apr. 7, 2009 (’331 Patent)

  • Technology Synopsis: This invention relates to the architecture of optical amplifiers, particularly for high-reliability applications like submarine systems (U.S. 7,515,331 Patent, col. 1:10-12). The solution is an apparatus with at least two amplifier modules (each with an optical amplifier and pump lasers) and a plurality of separate control modules. This separation allows the control electronics to be replaced or upgraded ("hot-swapped") without physically disturbing the optical connections or disabling the amplifier, thereby improving system reliability and serviceability (Compl. ¶134).
  • Asserted Claims: Claim 1 (Compl. ¶135).
  • Accused Features: The complaint alleges Nokia's products provide at least two amplifier modules and a plurality of control modules that are separate from the amplifier modules, where each control module is adapted to control a respective pump laser (Compl. ¶135).

III. The Accused Instrumentality

  • Product Identification: The accused products are Nokia's subsea optical networking systems that utilize its Photonic Service Engine 2 Super Coherent Technology and/or its 1620LM SLTE (Submarine Line Terminal Equipment) (Compl. ¶48).
  • Functionality and Market Context: The accused products are components of long-haul subsea telecommunication systems that transmit, receive, and transport data across oceans, connecting terrestrial data networks (Compl. ¶52). They include terminals, or "dry plants," which are located on land and serve as the interface between terrestrial networks and the undersea fiber optic cables (Compl. ¶58). A diagram in the complaint illustrates this connection between a transoceanic network and terrestrial networks (Compl. p. 17, "Transoceanic Network" figure). These products are alleged to incorporate features such as coherent optical transmission, dense wavelength-division multiplexing (DWDM), automatic wavelength dispersion compensation, and forward error correction (FEC), all of which serve to improve the capacity and performance of subsea data transmission (Compl. ¶61).

IV. Analysis of Infringement Allegations

’068 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
an input optical port for receiving a mixed optical signal containing a combination of coherent optical wavelength channels and non-coherent optical wavelength channels Nokia's Accused Products provide an input optical port for receiving a mixed optical signal with both coherent and non-coherent channels. ¶65 col. 6:46-50
an optical demultiplexer configured to separate the combination...such that a plurality of coherent optical wavelength channels...are provided onto a coherent optical path, and...a plurality of non-coherent optical wavelength channels...are provided onto a non-coherent optical path The products contain an optical demultiplexer that separates the incoming signal into a path for coherent channels and a path for non-coherent channels. ¶65 col. 6:50-59
a dispersive element...that operates such that a different amount of dispersion is applied to the plurality of non-coherent optical wavelength channels...than the amount of dispersion, if any, that is applied to the coherent optical path A dispersive element in the system applies a different amount of dispersion to the non-coherent channel path compared to the coherent channel path. ¶65 col. 6:60-67
an optical multiplexer configured to receive and combine the optical wavelength channels from the coherent and non-coherent optical paths to form a mixed coherent and non-coherent optical output signal An optical multiplexer recombines the channels from the separate paths into a single mixed output signal. A photograph of the accused 1620LM SLTE, which allegedly contains this functionality, is provided. ¶65; p. 23 col. 7:1-6
  • Identified Points of Contention:
    • Technical Questions: The complaint alleges the accused products perform the claimed separation and differential treatment of coherent versus non-coherent channels (Compl. ¶65). A central technical question will be what evidence supports this specific functionality. Does the accused product's "automatic wavelength dispersion compensation" (Compl. ¶61) operate by physically separating channels onto distinct paths for differential treatment as claimed, or does it use a different, potentially non-infringing, method?
    • Scope Questions: The dispute may turn on the definitions of "coherent optical wavelength channels" and "non-coherent optical wavelength channels." The scope of these terms will determine whether the signals processed by the accused system fall within the claim and are separated in the manner it requires.

’403 Patent Infringement Allegations

Claim Element (from Independent Claim 1) Alleged Infringing Functionality Complaint Citation Patent Citation
generating a periodic series of optical pulses defining a series of time slots, wherein one pulse appears in each time slot Nokia's Accused Products generate a periodic series of optical pulses that define a series of time slots. ¶79 col. 8:50-52
filtering the pulses by way of a filter to produce carrier pulses extending over more than one time slot The products filter the pulses to produce carrier pulses that extend over more than one time slot. A product diagram shows a "Filtering module." ¶79; p. 36 col. 8:53-55
modulating the pulses with data for transmission The products modulate the pulses with data for transmission. ¶79 col. 8:56-57
wherein for each of at least some of the carrier pulses, the filter gives rise to the corresponding carrier pulse having a temporal profile with a minimum substantially in the center of each of the time slots adjacent to the time slot for that corresponding carrier pulse... For at least some carrier pulses, the filter allegedly creates a temporal profile with a minimum located substantially in the center of adjacent time slots. ¶79 col. 8:57-63
the temporal profile of the corresponding carrier pulse further having an oscillating tail that extends from the minimum into at least one time slot that is even further from the time slot... The temporal profile of the carrier pulse is alleged to further have an oscillating tail extending from the minimum into at least one more distant time slot. ¶79 col. 8:63-67
  • Identified Points of Contention:
    • Technical Questions: A key evidentiary hurdle will be demonstrating that the optical signals generated by the accused products possess the highly specific temporal profile required by the claim. The analysis will likely require detailed characterization of the signal shape to determine if it has "a minimum substantially in the center" of adjacent time slots and the claimed "oscillating tail."
    • Scope Questions: The term "substantially in the center" will be a critical point of claim construction. The interpretation of "substantially" will define the degree of deviation permitted from the geometric center of a time slot, which may determine whether the accused product's signal profile falls within the scope of the claim.

V. Key Claim Terms for Construction

’068 Patent

  • The Term: "coherent optical wavelength channels" / "non-coherent optical wavelength channels"
  • Context and Importance: The claim's central concept is the physical separation and differential treatment of these two types of channels. The definitions are therefore critical to determining whether the accused system performs the claimed function on the types of signals specified.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification provides a functional definition, stating that the term "coherent" refers to "the ability to measure the electric field of the transmitted channel during detection (both amplitude and phase)" (’068 Patent, col. 2:55-59). This suggests the terms are defined by the detection method used at the receiver, not necessarily by a specific modulation format.
    • Evidence for a Narrower Interpretation: The patent's discussion of improving performance for "particular" coherent or non-coherent channels could be argued to limit the scope to specific embodiments or technologies known at the time of invention, rather than any signal that functionally meets the definition (’068 Patent, col. 2:5-7).

’403 Patent

  • The Term: "a temporal profile with a minimum substantially in the center of each of the time slots adjacent to the time slot for that corresponding carrier pulse"
  • Context and Importance: This phrase defines the core structural feature of the patented data format. Infringement hinges on whether the accused signal's physical shape meets this precise temporal and positional requirement. Practitioners may focus on this term because it is the primary point of novelty differentiating the claimed method from prior art data formats.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification explains the purpose of this feature is to ensure "that the effect of the overlap on neighbouring bits or pulses is minimised" (’403 Patent, col. 4:57-59). This functional language, combined with the word "substantially," may support a construction that allows for some deviation from the exact geometric center, as long as the pulse overlap is mitigated.
    • Evidence for a Narrower Interpretation: Figure 4b of the patent provides a specific graphical depiction of a filtered pulse with minima (43) positioned centrally in the adjacent time slots. A party could argue that this figure defines the scope of the claim, limiting it to pulses that closely conform to this illustrated embodiment (’403 Patent, Fig. 4b).

VI. Other Allegations

  • Indirect Infringement: For each asserted patent, the complaint alleges both induced and contributory infringement. Inducement is alleged based on Defendant providing "manuals, white papers, training, and/or other technical support" with the specific intent to cause customers to infringe (e.g., Compl. ¶70, ¶84). Contributory infringement is alleged on the basis that the accused products are "especially made and/or especially adapted for use in infringement" and are not a "staple article of commerce suitable for substantial non-infringing use" (e.g., Compl. ¶72, ¶86).
  • Willful Infringement: The complaint alleges willful infringement for all asserted patents. The basis includes allegations of both post-suit knowledge (e.g., "at least since the filing this Complaint," Compl. ¶66, ¶80) and pre-suit knowledge, arguing that Defendant "knew or should have known" of the patents because the subsea telecommunication market is small and Xtera is a "known pioneer with whom Nokia has great familiarity" (e.g., Compl. ¶73, ¶87).

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

  • A central technical question will be one of signal structure: does the data format generated by Nokia's systems exhibit the highly specific temporal profile required by the '403 patent, particularly the placement of a "minimum substantially in the center" of adjacent time slots, or is there a fundamental mismatch in the signal's physical characteristics?
  • A core issue will be one of functional equivalence: does Nokia's "automatic wavelength dispersion compensation" technology perform the specific function claimed in the '068 patent—physically separating "coherent" and "non-coherent" channels onto distinct optical paths for differential treatment—or does it achieve compensation through a different, non-infringing technical mechanism?
  • A key procedural issue will be the impact of post-grant proceedings: with asserted claims of the '798 and '637 patents having been cancelled or disclaimed after the complaint was filed, the scope of the dispute will be significantly narrowed, focusing the court's and parties' resources on the viability and alleged infringement of the remaining four patents.