Obviousness — US Patent 11431431

Obviousness Analysis of US 11,431,431 under 35 U.S.C. § 103

Date of Analysis: May 8, 2026

Patent at Issue: US 11,431,431 B2 ("the '431 patent")

This analysis evaluates the obviousness of the independent claims of the '431 patent in view of prior art cited during its prosecution. Under 35 U.S.C. § 103, a patent claim is invalid if the differences between the claimed invention and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art (POSITA).

I. Summary of the Invention

The core concept of the '431 patent is an optical communication apparatus (such as an add/drop multiplexer) that dynamically adjusts the power level of an optical signal using a variable attenuator. The key feature is that the specific attenuation amount is selected by a controller based on "connection information" it receives about the target device to which the signal is being sent. The claims specify that a different attenuation amount is used if the connected target is a "first optical device" versus a "second optical device," allowing the apparatus to adapt to the different power requirements of various types of network equipment. Claim 4 extends this to a system where a central "network management apparatus" provides this connection information to the optical apparatus.

II. Combination of Prior Art and Motivation to Combine

The independent claims of the '431 patent would have been obvious to a POSITA at the time of invention in view of the combination of the following prior art references cited in the patent's file history:

Primary Reference: US 6,959,149 B2 to Nortel Networks Limited (hereinafter "'149 patent"), titled "Power balancing in DWDM optical networks."
Secondary Reference: US 2013/0315580 A1 to Ciena Corporation (hereinafter "'580 application"), titled "Software defined networking photonic routing systems and methods."

A. Summary of Prior Art Teachings

The '149 patent discloses an optical network node (like a reconfigurable optical add/drop multiplexer or ROADM) that performs power balancing on different wavelength channels in a Dense Wavelength Division Multiplexing (DWDM) system. It explicitly teaches using an array of variable optical attenuators (VOAs) to adjust the power of individual optical signals after they have been demultiplexed. A control processor calculates and applies the necessary attenuation to each channel to equalize power levels, preventing signal degradation. This reference establishes the common practice of using controlled attenuators within an optical node to manage signal power on a per-channel basis.
The '580 application describes a Software-Defined Networking (SDN) architecture for controlling optical (photonic) networks. It teaches a centralized SDN controller (a "network management apparatus") that has a global view of the network topology and can dynamically configure network elements like optical switches and routers. This controller makes decisions based on high-level policies and knowledge of the network's state, including information about the various interconnected devices and their capabilities. The '580 application discloses that the SDN controller manages path computation and provisioning, which necessarily involves controlling physical layer parameters of the optical devices along the path.

B. Motivation to Combine

A person of ordinary skill in the art, when faced with the problem of managing optical power levels in a flexible and heterogeneous network, would have been motivated to combine the teachings of the '149 patent and the '580 application for the following reasons:

Automation of a Known Practice: The '149 patent teaches that power balancing is a critical function in DWDM systems and that it can be achieved with controllable attenuators. The '580 application teaches that modern networks are moving towards centralized, software-defined control for greater flexibility and automation. A POSITA would have found it obvious to apply the advanced control architecture of the '580 application to automate the necessary physical-layer task of power balancing taught in the '149 patent.
Addressing Heterogeneity: A key benefit of the SDN architecture in the '580 application is the ability to manage a network composed of diverse equipment. A POSITA would know that different types of optical devices (e.g., a short-reach client transceiver vs. a long-haul coherent transponder, or devices from different manufacturers) have different optimal input power requirements. Manually configuring attenuation for each connection is inefficient and error-prone, especially in a reconfigurable network. It would have been an obvious design choice to leverage the SDN controller's knowledge of the connected devices to automatically set the appropriate power levels.
Predictable Result: Combining the systems would yield the predictable result of a more efficient and robust network. The SDN controller from the '580 application would use its network inventory/topology data (the "connection information") to determine the type of device connected at a given port. It would then command the VOA controller in the optical node from the '149 patent to apply a pre-determined attenuation value suitable for that specific device type. This is not an inventive leap but rather the application of a known control paradigm (SDN) to a known optical component (VOA) to solve a well-understood problem (power balancing for heterogeneous devices).

III. Claim-by-Claim Obviousness Analysis

Independent Claim 1: Optical Communication Apparatus

"a demultiplexer configured to demultiplex a wavelength multiplexed signal...": Disclosed by the '149 patent (e.g., Fig. 2, demultiplexer 12). This is a fundamental component of any WDM node.
"an attenuator configured to attenuate one of the plurality of optical signals...": Disclosed by the '149 patent (e.g., Fig. 2, VOA array 14).
"a controller configured to receive a connection information on a connected target and send, to the attenuator, an attenuation amount according to the received connection information": The '149 patent discloses a control processor (16) that sends attenuation amounts to the VOAs (14). The '580 application discloses an SDN controller that has "connection information" about network devices and uses it to manage network elements. Combining these teaches a controller that uses connection information to set attenuation. The SDN controller of the '580 application provides the connection information, and the node controller of the '149 patent acts upon it to control the attenuator.
"wherein the controller sends the attenuation amount corresponding to a first optical device when the connected target...is the first optical device, and...a second optical device...": This is an obvious implementation detail that would result from the motivation to combine. A POSITA, seeking to automate power balancing for a heterogeneous network using the SDN controller of the '580 application, would inherently program the controller to apply different settings for different device types. Storing a profile or lookup table with attenuation values for "Device Type A," "Device Type B," etc., would be a standard and obvious engineering practice.

Therefore, claim 1 is obvious over the combination of the '149 patent and the '580 application.

Independent Claim 4: Optical Communication System

This claim recites a system comprising a "network management apparatus" and the optical communication apparatus of claim 1, where the management apparatus controls the optical apparatus.

This system is expressly taught by the combination. The SDN controller described in the '580 application is precisely a "network management apparatus." The combination involves this controller sending control information (the connection information and resulting attenuation amount) to the optical node disclosed in the '149 patent. This directly maps to the elements of claim 4, rendering it obvious for the same reasons as claim 1.

Independent Claim 7: Optical Communication Method

This claim recites the method steps performed by the apparatus of claim 1.

The steps of "demultiplexing," "attenuating," "receiving a connection information," and "attenuating the optical signal with an attenuation amount according to the received connection information" are the inherent operations of the obvious apparatus and system described above. Since the apparatus that performs the method is obvious, the method itself is also obvious.

IV. Conclusion

The independent claims of US Patent 11,431,431 are rendered obvious by the combination of US 6,959,149 B2 and US 2013/0315580 A1. The combination teaches all elements of the claims, and a person of ordinary skill in the art would have been motivated to combine their teachings to achieve a more automated and flexible optical network with optimized power levels, which is a predictable and expected outcome.