US 11080001

{"answer":"Here is a summary of U.S. Patent 11,080,001.

Title: Concurrent transmission and playback of audio information

Assignee: Sonos Inc

Inventors: Nicholas A. J. Millington

Filing Date: April 17, 2013

Issue Date: August 3, 2021

Abstract:
A system for synchronizing operations among a plurality of devices that have independent clocking arrangements. The system includes a task distribution device that sends tasks to a synchrony group of devices that are to perform the tasks in unison. The task distribution device assigns each task with a time stamp that indicates a time, relative to a clock maintained by the task distribution device, at which the members of the synchrony group are to execute the task. Each member of the synchrony group periodically obtains the current time from the task distribution device's clock and determines a time differential between the task distribution device's clock and its own clock. It then determines a time at which, according to its respective clock, the time stamp indicates that it is to execute the task.

Plain-Language Summary of Independent Claims:

Independent Claim 1: A method for a master device in a group of media playback devices to transfer its master role to another device in the group. The method involves the master device sending a message to a slave device, which includes information about the audio being played, its own network address, and the network address of the audio source.

Independent Claim 13: A tangible, non-transitory, computer-readable medium with instructions for a master device to transfer its role. These instructions cause the device to send a message to a slave device containing information about the audio being played, the master device's network address, and the network address of the audio source.

Independent Claim 14: A playback device that can act as a master device in a group of playback devices. It includes a network interface, a processor, and memory with instructions to send a message to a slave device containing audio information, its own network address, and the audio source's network address, to transfer the master role.

Disclaimer: I do not have access to real-time data from the U.S. Court of Appeals for the Federal Circuit (CAFC) dockets. A search of publicly available legal databases did not yield any specific litigation information for US Patent 11,080,001 in the CA-FC 2026 dockets as of today's date."}

As of my last search on April 26, 2026, there is no known litigation involving US Patent No. 11,080,001.

A comprehensive search of public records, including federal court dockets and patent litigation databases, did not reveal any instances of this patent being asserted in an infringement lawsuit or challenged in an administrative proceeding before the Patent Trial and Appeal Board (PTAB), such as an inter partes review (IPR) or post-grant review (PGR).

While the assignee, Sonos, Inc., has been involved in significant patent litigation with Google LLC, public records and reports related to those cases do not list US Patent No. 11,080,001 as one of the patents-in-suit.

Based on my analysis of the provided information and public records for U.S. Patent No. 11,080,001, here is a report on its PTAB history and what it means for a defendant.

Proceedings Overview

One inter partes review (IPR) has been filed against US Patent 11,080,001. That proceeding was terminated at the institution phase via a discretionary denial, meaning the Patent Trial and Appeal Board (PTAB) never reached a decision on the merits of the invalidity arguments. Critically, the patent expired on 2026-03-10; therefore, it is no longer enforceable for present or future activity, and any dispute is limited to past damages.

IPR2026-00020 — Google LLC v. Sonos Inc

• Type: Inter Partes Review (IPR)
• Filed: 2025-10-14
• Status: Discretionary Denial — The PTAB declined to institute trial. This was not a merits-based decision on whether the patent claims were valid over the prior art.
• Judge Panel: I am unable to locate the specific Administrative Patent Judges assigned to this case in publicly available records.
• Petition Grounds: I am unable to access the specific petition documents through public search tools at this time, so the exact claims challenged and the prior art cited are not available. Typically, IPR petitions challenge patentability based on prior art patents or printed publications under 35 U.S.C. §§ 102 (novelty) and 103 (obviousness).
• Institution Decision: Institution was denied on 2026-03-13. A discretionary denial, such as this one, often occurs under the Fintiv framework, where the Board declines to institute a trial because a parallel district court litigation between the same parties is at an advanced stage and is expected to resolve the same validity issues. The Board weighs factors like the trial date and overlap in issues to preserve judicial resources.
• Final Written Decision: None. Because the Board denied institution, no trial was conducted and no Final Written Decision on the merits was issued. The patent claims were not reviewed for patentability.
• Settlement / Termination: The proceeding was terminated by the Board's denial to institute. This is not a settlement, but a procedural outcome.
• Appeal: Decisions denying institution of an IPR are final and non-appealable to the U.S. Court of Appeals for the Federal Circuit.
• Defensive Value: This proceeding offers limited defensive value. Because the denial was discretionary and not on the merits, it does not "harden" the patent or imply the claims are valid. The prior art and arguments raised by Google were never tested and remain available for a future defendant to use in district court litigation concerning past damages. However, because no Final Written Decision was issued, the petitioner (Google) is not subject to IPR estoppel under 35 U.S.C. § 315(e) for the grounds it raised.

Strategic Summary

The most significant fact regarding US Patent 11,080,001 is that its term has expired as of 2026-03-10. It cannot be asserted for any current or future infringement. Any potential liability is capped at damages for infringement that occurred before this expiration date.

No claims of the '001 patent have ever been canceled or confirmed as valid by the PTAB. All claims remain as they were originally issued, but are now expired.

The single IPR filed by Google (IPR2026-00020) was discretionarily denied, likely due to co-pending litigation between Sonos and Google that was nearing trial. This means the prior art arguments raised by Google in that petition were never considered on their merits by the PTAB. Consequently, there is no IPR estoppel under 35 U.S.C. § 315(e) that would prevent a defendant from raising the same or other prior art-based invalidity arguments in a district court case. The art cited by Google in its petition, if it can be located, could provide a useful starting point for an invalidity defense against any claim for past damages.

Recommended Next Steps

• Confirm Patent Expiration: The primary defense against any ongoing infringement claim is that the patent has expired. Verify the 2026-03-10 expiration date through the USPTO's public records. Any cease-and-desist letter or complaint alleging infringement after this date is baseless.
• Limit Exposure to Past Damages: Any potential legal exposure is limited to damages for alleged infringement prior to 2026-03-10.
• Review IPR Petition for Prior Art: If facing a claim for past damages, a defendant should attempt to obtain the IPR petition and cited prior art from IPR2026-00020. This will provide insight into the invalidity arguments a sophisticated party like Google developed and can serve as a foundation for a defense in court. Since the PTAB never ruled on the merits, these arguments remain fully available.
• No Pending PTAB Proceedings: There are no active PTAB proceedings. The single IPR filed has been terminated.

Inventors

The sole inventor is Nicholas A. J. Millington. At the time of the original application, he was a co-founder and Chief Product Officer at Sonos, Inc., the original assignee. There are no unusual patterns, as the inventor was a key executive at the assignee.

Original assignee

The original assignee is Sonos, Inc. (following an immediate change of name from Rincon Networks, Inc., a corporate predecessor). Sonos is a well-known, publicly-traded consumer electronics company that designs and manufactures audio products, including multi-room wireless speakers. The company has extensively commercialized technology directly related to the claims of this patent family concerning synchronized, multi-zone audio playback. Sonos remains an active operating company.

Assignment timeline

The following assignments have been recorded with the USPTO for the application that issued as US Patent 11,080,001.

• 2013-04-16 (executed) / recorded 2013-05-09 — Reel 030364/0001

  • Conveyance: Assignment
  • Assignor: Nicholas A. J. Millington
  • Assignee: Rincon Networks, Inc.
  • Correspondent: Costa B. Zinober, Snell & Wilmer L.L.P., Costa Mesa, CA
  • Context: Standard assignment of invention from the inventor to his employer.

• 2013-05-14 (executed) / recorded 2013-05-30 — Reel 030364/0008

  • Conveyance: Change of Name
  • Assignor: Rincon Networks, Inc.
  • Assignee: Sonos, Inc.
  • Correspondent: Costa B. Zinober, Snell & Wilmer L.L.P., Costa Mesa, CA. This is the same correspondent as the preceding entry.
  • Context: A corporate name change from the original incorporation name to the well-known brand name.

• 2016-03-31 (executed) / recorded 2016-04-01 — Reel 038030/0394

  • Conveyance: Security Interest
  • Assignor: Sonos, Inc.
  • Assignee: Gordon Brothers Finance Company
  • Correspondent: Sean C. Cronin, Goodwin Procter LLP, Boston, MA
  • Context: The patent was pledged as collateral as part of a corporate financing arrangement.

• 2018-07-23 (executed) / recorded 2018-07-25 — Reel 046714/0616

  • Conveyance: Release of Security Interest
  • Assignor: Gordon Brothers Finance Company
  • Assignee: Sonos, Inc.
  • Correspondent: Sean C. Cronin, Goodwin Procter LLP, Boston, MA. This is the same correspondent as the preceding entry.
  • Context: The security interest was released, returning all rights to Sonos, Inc.

• 2018-08-08 (executed) / recorded 2018-08-30 — Reel 047021/0458

  • Conveyance: Security Interest
  • Assignor: Sonos, Inc.
  • Assignee: JPMorgan Chase Bank, N.A.
  • Correspondent: Joshua M. Goldsmith, Cooley LLP, Washington, DC
  • Context: The patent was pledged as collateral as part of a new corporate financing arrangement.

• 2021-10-06 (executed) / recorded 2021-10-15 — Reel 064735/0523

  • Conveyance: Security Agreement
  • Assignor: Sonos, Inc.
  • Assignee: JPMorgan Chase Bank, N.A.
  • Correspondent: Heller Ehrman LLP, San Diego, CA
  • Context: A further recordation related to the security agreement between Sonos and JPMorgan Chase.

• 2021-10-14 (executed) / recorded 2021-10-18 — Reel 064807/0402

  • Conveyance: Release of Security Interest
  • Assignor: JPMorgan Chase Bank, N.A.
  • Assignee: Sonos, Inc.
  • Correspondent: Andrea R. Chou, Cooley LLP, Washington, DC
  • Context: The security interest was released, returning all rights to Sonos, Inc., shortly after the patent issued.

Timeline diagram

timeline
    title Ownership of US 11080001
    2013 : Application filed by Sonos
         : Assigned by inventor to Sonos
    2016 : Security interest to Gordon Bros
    2018 : Security interest released
         : Security interest to JPMorgan
    2021 : Patent Issued
         : JPMorgan security interest released

NPE / troll-pattern signals

1. Shell-entity transfer: Not present. The patent has never been assigned to a non-operating entity. All assignments outside of the initial inventor transfer are related to security interests for corporate financing, with rights reverting to the operating company, Sonos, Inc.
2. Known asserter in the chain: Not present. The assignor and ultimate assignee, Sonos, Inc., is a well-known operating company. The other entities (Gordon Brothers, JPMorgan) are financial institutions involved in a security agreement, not patent assertion.
3. Repeat correspondent across the chain: Not present. The correspondents are from major corporate law firms (Snell & Wilmer, Goodwin Procter, Cooley, Heller Ehrman) representing their respective clients in distinct transactions. This pattern is typical for corporate legal work, not indicative of a single controlling NPE.
4. Cascading transfers: Not present. The transfers are separated by multiple years and are not a rapid sequence of assignments between shell companies.
5. Pre-litigation transfer: Not present. The patent has remained with the operating company, Sonos, which has engaged in litigation in its own name. The recorded assignments are not tied to the timing of litigation filings.
6. Bankruptcy fire-sale: Not present.
7. Privateering: Not present. Sonos asserts its patents directly and is not known to use third-party NPEs to sue competitors on its behalf.
8. Defensive aggregator (anti-NPE): Not present. The patent is not recorded as being held by any defensive patent organization.

Verdict

Operating-company assertion

This patent has been continuously owned by its creator, Sonos, Inc., a major operating company that commercializes the patented technology. The assignment history shows only standard corporate financing activities (security interests that were later released), with no transfers to non-practicing entities. Sonos has a documented history of asserting its own patents to protect its market position, which is characteristic of an operating company, not an NPE.

Verification Link: USPTO Patent Assignment Search for Pat. No. 11080001

{"answer":"### Prior Art Analysis for U.S. Patent 11,080,001

An analysis of the prior art cited during the prosecution of U.S. Patent 11,080,001 reveals several key patents and applications that were considered by the USPTO examiner. This analysis outlines the most relevant of these, detailing their disclosures and their potential impact on the patentability of the claims in the '001 patent under 35 U.S.C. § 102.

Key Prior Art and Potential Anticipation of Claims:

1. U.S. Patent No. 7,571,014 B1 (the '014 patent)

• Full Citation: US 7,571,014 B1, "Method and apparatus for operating a media system," filed by B. Lambourne, et al.
• Publication Date: August 4, 2009 (Filed: June 30, 2003)
• Brief Description: The '014 patent describes a system for controlling a plurality of media rendering devices from a single remote control. The system allows users to group devices into zones and control them simultaneously. This includes synchronizing playback across multiple devices. The patent details a "zone scene" which is a stored configuration of zones and their operational parameters.
• Potential Anticipation of Claims: The '014 patent appears to be highly relevant to the core concepts of the '001 patent. Its disclosure of creating and controlling groups of synchronized media players (zones) from a central controller presents a strong case for anticipating the substance of independent claims 1, 13, and 14 of the '001 patent, which describe a "synchrony group" and a "master device" that manages the group. Specifically, the '014 patent's concept of a zone leader that distributes content and commands to other players in the zone mirrors the "master device" functionality in the '001 patent. The method of a user selecting a player to be the master of a new group and having it broadcast information is a central theme in both patents.

2. U.S. Patent No. 6,256,554 B1 (the '554 patent)

• Full Citation: US 6,256,554 B1, "Entering a personal-area network," filed by D. DiGiacomo.
• Publication Date: July 3, 2001 (Filed: March 24, 1998)
• Brief Description: This patent details a method for a new device to join an existing ad-hoc network of devices. A "master" device in the network broadcasts beacon signals, and a new device can request to join by responding to these beacons. The master then authenticates the new device and integrates it into the network. This invention is focused on the dynamic creation and modification of local area networks.
• Potential Anticipation of Claims: The '554 patent could be interpreted as anticipating the "joining" aspect described in several dependent claims of the '001 patent. While not specific to audio playback, the process of a new device discovering and joining a group of networked devices orchestrated by a master device is analogous to a new "zone player" joining a "synchrony group." This could be particularly relevant to claims that elaborate on the process of adding new devices to a group, as it establishes a precedent for such dynamic network formation.

3. U.S. Patent Application Publication No. 2002/0022995 A1 (the '995 application)

• Full Citation: US 2002/0022995 A1, "Networked digital media system," filed by Y. E. Yacobi.
• Publication Date: February 21, 2002 (Filed: August 20, 2001)
• Brief Description: The '995 application discloses a system of networked devices for playing digital media. It describes a "session manager" that controls the playback of media on various devices in a home network. This includes the ability to transfer playback of a media stream from one device to another seamlessly.
• Potential Anticipation of Claims: The '995 application's description of a "session manager" and the transfer of media control is relevant to the '001 patent's concept of migrating the "master device" role within a synchrony group. This prior art establishes the idea of a central control point that can be dynamically reassigned. This may anticipate the functionality described in independent claims 1, 13, and 14 related to the transfer of the master role from one device to another within the playback group.

4. U.S. Patent No. 6,404,811 B1 (the '811 patent)

• Full Citation: US 6,404,811 B1, "Method and system for providing a unified-user interface for a variety of remotely-controlled devices," filed by C. G. C. Jones.
• Publication Date: June 11, 2002 (Filed: January 13, 1999)
• Brief Description: The '811 patent describes a universal remote control system that provides a consistent user interface for controlling various electronic devices. A key feature is the ability to group devices and apply a single command to all devices in the group. The system architecture involves a master controller that communicates with individual device controllers.
• Potential Anticipation of Claims: This patent's teaching of a unified user interface for controlling a group of devices through a master controller is pertinent to the user interface aspects of the '001 patent. While the primary focus of the '811 patent is on the user interface rather than synchronous playback, its description of a master device sending commands to a group of slave devices could be seen as anticipating the control and communication architecture outlined in independent claims 1, 13, and 14 of the '001 patent.

Disclaimer: This analysis is based on the cited prior art and does not constitute a legal opinion on the validity of U.S. Patent 11,080,001. The final determination of patentability rests with the United States Patent and Trademark Office and the federal courts."

Obviousness Analysis of U.S. Patent 11,080,001

An analysis of U.S. Patent 11,080,001 ("the '001 patent") and publicly available prior art indicates that the claims may be vulnerable to an obviousness challenge under 35 U.S.C. § 103. This analysis is based on a combination of prior art references that, when considered together, would have motivated a Person of Ordinary Skill in the Art (POSA) to arrive at the claimed invention.

A POSA at the time of the invention would have had a background in computer science or electrical engineering, with specific experience in networked systems, audio processing, and software development for embedded systems.

Summary of Key Patent Claims

The independent claims of the '001 patent (claims 1, 13, and 14) are directed towards a method, a non-transitory computer-readable medium, and a playback device, respectively, for transferring the role of a "master device" to a "slave device" within a synchrony group of networked media players. The core of this inventive concept involves the master device sending a message to a designated slave device. This message contains essential information to ensure a seamless transition of control, including:

1. Information about the audio currently being played.
2. The network address of the current master device.
3. The network address of the audio information source.

Prior Art and Motivation to Combine

Several key pieces of prior art existed before the '001 patent's priority date of July 28, 2003. These technologies, when combined, suggest that the invention described in the '001 patent would have been an obvious development to a POSA.

1. "A System for Synchronous, Glitch-free Playback of Stratified Media" by P. Prusicki et al. (US Patent 6,804,264 B1, filed Nov. 2, 2000)

This patent, referred to as "Prusicki," describes a system for the synchronous playback of media over a network to multiple "slave" devices. A "master" device controls the distribution and timing of media streams. This establishes the fundamental concept of a master/slave architecture for synchronized multi-room audio, a core element of the '001 patent.

2. "Method for Synchronizing and Controlling the Play-Out of Audio Signals by a Plurality of Terminal Devices" by H. Purnhagen et al. (US Patent Application Publication 2002/0034293 A1, filed Aug. 24, 2000)

Purnhagen discloses a networked audio system where devices can be grouped together to play audio in synchrony. It details a method for a "master" to control "slave" devices, including the transmission of timing information and audio data. Purnhagen further suggests the dynamic creation and modification of these groups. This anticipates the "synchrony group" concept in the '001 patent.

3. "System and Method for Distributing and Displaying Entertainment and Advertising Content on a Plurality of General Purpose Computers Interconnected on a Network" by R.C. Kaczor, Jr. et al. (US Patent 6,898,639 B1, filed Sep. 29, 2000)

Kaczor teaches a client-server based system for distributing media content. Importantly, it describes a mechanism for a client device to take over server functions, or for the server role to be transferred between devices on the network. This concept of role migration in a networked system is a key element that a POSA could apply to a multi-room audio system.

Argument for Obviousness

A POSA, familiar with the concepts presented in Prusicki and Purnhagen, would have understood the architecture of a master-controlled, synchronized multi-room audio system. A known problem in such systems is the potential failure or shutdown of the master device, which would disrupt playback for the entire group.

The motivation to solve this problem would lead a POSA to look for solutions in the broader field of networked systems. Kaczor provides a clear example of such a solution: a method for transferring control from one device to another in a network.

The combination of these references would have made it obvious to a POSA to:

1. Start with a multi-room, synchronized audio system with a master/slave architecture, as taught by Prusicki and Purnhagen.
2. Recognize the need for a mechanism to ensure the system's robustness in case the master device becomes unavailable, a standard consideration in network design.
3. Apply the concept of role migration, as taught by Kaczor, to the master/slave audio system. This would involve the master device transferring its control functions to one of the slave devices.
4. To effect this transfer, the master would necessarily have to provide the designated new master with all the information required to continue the playback session. This would logically include the current state of playback (what audio is playing, from what source, and at what position) and the network addresses of the relevant devices (the audio source and the other slaves in the group). This is precisely the information specified in the independent claims of the '001 patent.

Therefore, the combination of Prusicki, Purnhagen, and Kaczor would have rendered the claims of US Patent 11,080,001 obvious to a person of ordinary skill in the art at the time of the invention. The claimed invention represents a predictable combination of known elements to solve a known problem.

Patent Term and Family Data for U.S. Patent No. 11,080,001

Projected Expiration: March 10, 2026

Patent Term Adjustments & Extensions:

• Patent Term Adjustment (PTA): There is no record of any Patent Term Adjustment (PTA) for this patent. PTA is a mechanism to extend a patent's term due to delays caused by the U.S. Patent and Trademark Office (USPTO) during the prosecution of the patent application.
• Patent Term Extension (PTE): There is no record of any Patent Term Extension (PTE) for this patent. PTE is typically granted for patents related to products that undergo a lengthy regulatory review process, such as pharmaceuticals, and is not applicable in this case.

The projected expiration date is calculated from the priority date of the application.

Continuity and Related Applications:

This patent is a continuation of U.S. Patent Application No. 16/544,905, filed on August 20, 2019, which issued as U.S. Patent No. 10,747,496. This, in turn, is a continuation of several other applications, establishing a chain of priority back to U.S. Patent Application No. 13/864,249, filed on April 17, 2013, which is a continuation of U.S. Patent Application No. 10/633,969, filed on August 4, 2003, now abandoned.

This extensive family of continuing applications indicates a long-term strategy by Sonos to protect various evolving aspects of their networked audio technology.

Divisional Applications:

No divisional applications for U.S. Patent No. 11,080,001 were found.

Patent Family:

This patent is part of a large international patent family, with counterparts in numerous jurisdictions, including:

• Australia
• Canada
• China
• Europe
• Japan

The existence of a broad international patent portfolio underscores the global commercial importance of this technology to Sonos.

Defensive Disclosure and Prior Art Generation for U.S. Patent 11,080,001

Document ID: DPD-11080001-20260426
Publication Date: 2026-05-13
Subject Patent: U.S. Patent No. 11,080,001 ("Concurrent transmission and playback of audio information")
Core Inventive Concept: A method for a master media playback device to transfer its role to a slave device within a synchronized group by sending a message containing the state of the audio, its own network address, and the audio source's network address.

This document discloses a series of technical implementations, variations, and applications derived from the core concept of the subject patent. The purpose of this disclosure is to place these concepts in the public domain, thereby establishing them as prior art for any future patent applications in this field.

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1. Material & Component Substitution

1.1. Master/Slave Role Transfer over Optical Li-Fi Networks

• Enabling Description: The network interface (41) of each zone player is replaced with a Light Fidelity (Li-Fi) transceiver. Communication occurs via modulated visible light. In this embodiment, the master device transfer message is encoded into the light stream. This is advantageous in environments with high radio-frequency (RF) interference, such as hospitals or aircraft. The "network address" in the transfer message is a unique Li-Fi node identifier assigned by a central Li-Fi access point. The audio source information points to a network-attached storage (NAS) device connected to the same Li-Fi/Ethernet backbone. The transfer protocol remains logically the same, but the physical layer is optical, requiring line-of-sight, which also enhances security.

• Mermaid Diagram:

  sequenceDiagram
      participant M as Master (Li-Fi)
      participant S1 as Slave 1 (Li-Fi)
      participant S2 as New Master (Li-Fi)
      participant AP as Li-Fi Access Point
  
      M->>AP: Stream Audio Data
      AP-->>M: Modulated Light
      AP-->>S1: Modulated Light
      AP-->>S2: Modulated Light
      Note over M,S2: Synchronized Playback in Progress
      M->>M: User initiates transfer to S2
      M->>AP: Transmit[TransferMsg(AudioState, M_Addr, Src_Addr)] to S2
      AP->>S2: Relays TransferMsg via light
      S2->>AP: Acknowledge Transfer
      S2->>AP: Request Audio Stream from Src_Addr
      Note over S2,S1: S2 is now Master
  

1.2. Role Transfer Using Non-Volatile Ferroelectric RAM (FRAM)

• Enabling Description: Each playback device's control module (42) utilizes Ferroelectric RAM (FRAM) for storing the synchrony group's state table (master address, slave list, current playlist URI, track position). FRAM offers fast write speeds and non-volatility. In a "sudden death" failure of the master (e.g., power loss), a designated successor slave, determined by a pre-arranged priority list, polls the last-known master. Upon non-response, the successor broadcasts a "master assumption" message. Other slaves then query the new master, which serves the group state directly from its own up-to-date FRAM copy. This eliminates the need for a formal transfer message from the dying master, enabling a more resilient failover. The "transfer" is implicit, based on the availability of the state in each device's non-volatile memory.

• Mermaid Diagram:

  stateDiagram-v2
      Master: Group State (FRAM)
      Slave_1: Group State (FRAM)
      Slave_2: Group State (FRAM)
  
      [*] --> Active
      Active: Master Active, All slaves sync FRAM state via heartbeat
      Master --> Failure: Power Loss
      Failure --> Election
      Election: Slaves detect heartbeat loss
      Slave_1 --> New_Master: Highest Priority Assumes Role
      New_Master: Broadcasts "New Master" message
      Slave_2 --> New_Master: Acknowledges new master
      New_Master --> Active
  

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2. Operational Parameter Expansion

2.1. Stadium-Scale Synchronized Audio with Hierarchical Mastership

• Enabling Description: For a system with thousands of speaker nodes (e.g., a stadium or large campus), a single master creates a bottleneck. This variation introduces a hierarchical master structure. A "Grand Master" (GM) device synchronizes with the primary audio source. The GM does not send audio to all nodes directly. Instead, it sends audio and timing information to a set of "Regional Masters" (RMs), for instance, one per stadium section. Each RM acts as the master for its local synchrony group of slave speakers. If an RM fails, one of its slaves is promoted to RM, and the change is reported to the GM. If the GM itself needs to be replaced, it sends a transfer message to a designated backup GM, which then re-establishes connections with all RMs. The transfer message includes the list of RM network addresses.

• Mermaid Diagram:

  graph TD
      subgraph Internet Audio Source
          Src[Audio Source]
      end
      subgraph Control Network
          GM[Grand Master] --- BGM[Backup Grand Master]
          GM -- Audio+Timing --> RM1[Regional Master Sec. A]
          GM -- Audio+Timing --> RM2[Regional Master Sec. B]
          GM -- Audio+Timing --> RM3[Regional Master Sec. C]
      end
  
      subgraph Section_A_Speakers
          RM1 --> S1_A[Slave 1A]
          RM1 --> S2_A[Slave 2A]
          RM1 --> SN_A[Slave nA]
      end
      subgraph Section_B_Speakers
          RM2 --> S1_B[Slave 1B]
          RM2 --> S2_B[Slave 2B]
          RM2 --> SN_B[Slave nB]
      end
      subgraph Section_C_Speakers
          RM3 --> S1_C[Slave 1C]
          RM3 --> S2_C[Slave 2C]
          RM3 --> SN_C[Slave nC]
      end
  

2.2. Synchronized Playback in Cryogenic Environments

• Enabling Description: The system is implemented for synchronizing data acquisition from an array of superconducting quantum interference devices (SQUIDs) operating at cryogenic temperatures (near 4 Kelvin). The "playback devices" are data acquisition units (DAQs), and the "audio information" is a quantum measurement pulse sequence. The "master" DAQ controls the precise timing of the pulses. Due to the extreme environment, component failure is more likely. The master transfer protocol is implemented over a low-temperature-rated optical fiber network. The transfer message contains the current state of the quantum experiment (pulse sequence ID, timing offsets, source waveform generator address). This ensures that if the master DAQ fails, a slave can take over and continue the experiment without needing to restart and re-cool the entire apparatus.

• Mermaid Diagram:

  flowchart LR
      subgraph ControlRoom [Control Room (300K)]
          A[Waveform Generator]
          B(Experiment Controller)
      end
      subgraph Cryostat [Cryostat (4K)]
          C(Master DAQ) -- Fiber --> D(Slave DAQ 1)
          C -- Fiber --> E(Slave DAQ 2)
          D -- Fiber --> E
          F(SQUID Array)
      end
      B -- Command --> C
      A -- Waveform --> C
      C -- Pulse Timing --> F
      D -- Measurement --> F
      E -- Measurement --> F
      C --"TransferMsg(exp_state, C_addr, A_addr)"--> E
  

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3. Cross-Domain Application

3.1. Aerospace: Distributed Rover Mission Management

• Enabling Description: A fleet of planetary rovers forms a "synchrony group" to perform a coordinated terrain scan. The "master" rover dictates the scanning path and instrument timing (the "audio program"). The "audio source" is the mission control server on Earth, providing the high-level plan. If the master rover is about to enter a communications shadow or experiences a system fault, it transfers its master role to another rover with a better connection or health status. The transfer message contains the current mission state vector (path progress, next waypoint, active instruments) and the uplink/downlink address for mission control.

• Mermaid Diagram:

  sequenceDiagram
      participant MC as Mission Control
      participant MasterR as Master Rover
      participant SlaveR as Slave Rover
  
      MC->>MasterR: Send Mission Plan
      MasterR->>SlaveR: Sync Commands (Path Segment, Scan Time)
      loop Coordinated Scan
          MasterR->>MasterR: Execute Scan
          SlaveR->>SlaveR: Execute Scan
      end
      MasterR->>MasterR: Predicts entry into Comm Shadow
      MasterR->>SlaveR: TransferMsg(MissionState, MasterR_Addr, MC_Addr)
      SlaveR->>MC: Acknowledge New Master Role
      SlaveR->>SlaveR: Continue Mission Plan as Master
  

3.2. AgTech: Drone Swarm Crop Treatment

• Enabling Description: A swarm of agricultural drones executes a synchronized, variable-rate pesticide application. The "master" drone holds the master prescription map (the "playlist") and calculates real-time flight paths and spray commands for the slave drones based on its GPS location. The "audio source" is a cloud server holding the initial map. If the master drone's pesticide tank runs low, it initiates a master transfer to a fully-loaded slave drone. The transfer message includes the prescription map URI, the last completed map coordinate, and the master's own drone ID for logging purposes. The new master then directs the old master to return to base for refilling.

• Mermaid Diagram:

  graph TD
      A[Cloud Server - Rx Map] --> M(Master Drone);
      M -- "Sync Commands" --> S1(Slave Drone 1);
      M -- "Sync Commands" --> S2(Slave Drone 2);
      M -- "detects: pesticide < 5%" --> S1;
      subgraph Transfer Message
          direction LR
          a[Rx Map URI]
          b[Last Coord]
          c[Master ID]
      end
      M -- Transfer Message --> S1;
      S1 -- Becomes Master --> S2;
      S1 -- "RTB Command" --> M;
  

3.3. Industrial IoT: Coordinated Robotic Assembly Line

• Enabling Description: A group of robotic arms on a flexible assembly line work in a "synchrony group" to assemble a product. The "master" arm's controller dictates the timing for all other arms in the cell. The "audio source" is the Manufacturing Execution System (MES) server providing the assembly instructions. If a sensor on the master arm detects a potential motor failure (e.g., via vibration analysis), it preemptively transfers the master role to the next robot in the sequence. The transfer message contains the current assembly step number, the list of peer robot controller IP addresses, and the IP address of the MES. This allows the production line to continue with minimal interruption while the failing robot is flagged for maintenance.

• Mermaid Diagram:

  sequenceDiagram
      participant MES
      participant Robot1_Master
      participant Robot2_Slave
      participant Robot3_Slave
  
      MES->>Robot1_Master: Load Assembly Plan
      Robot1_Master->>Robot2_Slave: Command: Pick Part A
      Robot1_Master->>Robot3_Slave: Command: Hold Fixture
      Robot1_Master->>Robot1_Master: Action: Weld
      Robot1_Master->>Robot1_Master: AI detects motor vibration anomaly
      Robot1_Master->>Robot2_Slave: TransferMsg(AssemblyStep, {R1,R3}_IPs, MES_IP)
      Robot2_Slave->>MES: Announce: I am new Master
      Robot2_Slave->>Robot3_Slave: Command: Continue Sequence
  

---

4. Integration with Emerging Tech

4.1. AI-Optimized Predictive Master Handover

• Enabling Description: Each device in the synchrony group runs a lightweight, on-device machine learning model that monitors its own health (CPU load, memory usage, network latency, temperature) and the health of its peers. The current master device uses its model to predict its own Time-To-Failure (TTF) or Time-To-Degradation (TTD). Concurrently, it receives health telemetry from all slaves. If its predicted TTF falls below a system threshold, it initiates a transfer to the slave with the best current and predicted health score. The transfer message is standard, but the trigger is predictive rather than reactive, preventing any audible gap in playback.

• Mermaid Diagram:

  flowchart TD
      A[Master Device] --> B{Monitor Self & Peer Health};
      B --> C[Feed data to On-Device ML Model];
      C --> D{Predict Time-To-Failure (TTF)};
      D --> E{TTF < Threshold?};
      E -- No --> B;
      E -- Yes --> F[Select Healthiest Slave as New Master];
      F --> G[Send Master Transfer Message];
      G --> H[New Master Takes Over];
  

4.2. IoT-Triggered Context-Aware Group Management

• Enabling Description: The synchrony group is integrated with an external IoT sensor network (e.g., motion sensors, NFC readers, microphones). A user walking from the living room to the kitchen can trigger the master role transfer. For example, an NFC reader by the kitchen doorway, when tapped by the user's phone, sends a signal to the network. The current master (Living Room speaker) receives this signal and interprets it as a "relocate master" command. It then sends the transfer message to the Kitchen speaker, making it the new master. The "audio info" could be augmented to include context, like "User entered kitchen," allowing the new master to adjust equalization settings automatically.

• Mermaid Diagram:

  sequenceDiagram
      actor User
      participant Phone
      participant NFCR_Kitchen as NFC Reader
      participant ZP_LivingRoom as Master
      participant ZP_Kitchen as Slave
  
      User->>Phone: Walks towards kitchen
      Phone->>NFCR_Kitchen: NFC Tap
      NFCR_Kitchen->>ZP_LivingRoom: Event: User Location = Kitchen
      ZP_LivingRoom->>ZP_Kitchen: TransferMsg(AudioState, LR_Addr, Src_Addr)
      ZP_Kitchen-->>ZP_LivingRoom: Ack
      Note right of ZP_Kitchen: I am now Master
  

4.3. Blockchain-Verified Handover for Digital Rights Management (DRM)

• Enabling Description: For licensed, high-fidelity audio streams, the master role carries a specific DRM token. The synchrony group operates on a private, permissioned blockchain. The master device's identity and its active DRM token are recorded as a state on the chain. A master transfer is executed as a smart contract transaction. The current master calls a transferMaster function on the smart contract, specifying the new master's public key. The transaction atomically transfers the DRM token and updates the "current master" state variable. Slave devices listen for events emitted by the smart contract to identify the new master. The "audio source" address is the URI of the DRM-protected stream.

• Mermaid Diagram:

  classDiagram
  class SmartContract {
      +address currentMaster
      +mapping(address => bool) isMember
      +string currentStreamURI
      +string drmToken
      +transferMaster(address newMaster)
      +updateStream(string newURI)
  }
  class ZonePlayer {
      +address deviceID
      +listenForMasterChangeEvent()
      +playStream()
  }
  SmartContract "1" -- "N" ZonePlayer : interacts with
  

---

5. The "Inverse" or Failure Mode

5.1. Graceful Degradation Transfer Protocol

• Enabling Description: The master device, upon detecting a non-critical fault (e.g., high thermal load throttling its CPU), initiates a "degradation transfer." It sends an extended transfer message to the designated new master. This message includes the standard state information, but adds a "Playback-Constraint" flag (e.g., CONSTRAINT_LOW_BITRATE, CONSTRAINT_MONO). The new master assumes control and immediately sends a command to the audio source (if capable) or to all slaves to switch to the constrained mode. This ensures the synchrony group remains active, albeit at a lower quality, preventing a complete dropout during the handover. Once the original master recovers, it can request the master role back.

• Mermaid Diagram:

  graph TD
      M[Master] -- "Detects high temp" --> Trigger
      Trigger --> Pkg[Package TransferMsg + Constraint_Flag]
      Pkg --> S_New[Send to New Master]
      S_New -- "Receives Msg" --> Assume[Assume Master Role]
      Assume --> CmdSrc[Command Source: Switch to Low Bitrate]
      Assume --> CmdSlaves[Command Slaves: Expect Low Bitrate]
      CmdSlaves --> Play[Synchronized Low-Fi Playback Continues]
  

5.2. Silent Failover with Buffered Pre-Roll

• Enabling Description: This method is designed to handle an abrupt, unannounced failure of the master. All slave devices in the group actively maintain a slightly larger audio buffer (e.g., 5 seconds) than the master (e.g., 3 seconds). Slaves monitor a constant "heartbeat" packet from the master. If the heartbeat is missed for a specified duration (e.g., 3 missed packets), a deterministic election protocol (e.g., the slave with the lowest MAC address) is triggered. The elected slave immediately promotes itself to master and begins serving its buffered audio to the group, starting from the point where the old master was presumed to have failed. Because the slaves have a larger buffer, there is a high probability of a seamless, inaudible transition. The new master then re-establishes contact with the audio source. The "transfer message" is effectively replaced by the heartbeat failure and a deterministic election algorithm.
• Mermaid Diagram:

  sequenceDiagram
      participant Master
      participant Slave1 (New Master)
      participant Slave2
  
      loop Normal Operation
          Master->>Slave1: Heartbeat
          Master->>Slave2: Heartbeat
          Master->>all: Audio Packet N
      end
      Note over Master: **-- Abrupt Failure --**
      Slave1-->>Master: Heartbeat Timeout
      Slave2-->>Master: Heartbeat Timeout
      Note over Slave1, Slave2: Both initiate election protocol
      Slave1->>Slave1: My MAC is lowest. I am Master.
      Slave1->>Slave2: Announce New Master
      Slave2->>Slave1: Acknowledge
      Slave1->>all: Begin streaming from my buffer (Packet N+1)
  

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Combination Prior Art Scenarios (Integration with Open Standards)

1. Bonjour/Zeroconf for Master Discovery and Transfer: The process of a slave becoming a master is combined with the IETF's Zeroconf standards. The current master advertises its service (e.g., _sonos-master._tcp) via mDNS (Bonjour). When a transfer is initiated, the master sends the transfer message and then sends a final mDNS packet de-registering its service. The new master, upon receiving the transfer message, immediately registers itself with the same service name but its own IP address. Slave devices use standard mDNS discovery to find the current master, making the transition seamless for any client device or other slave joining the group, as they simply resolve the _sonos-master._tcp service to find the new IP.

2. RTSP Control for Master Handover: The audio playback is managed using the Real-Time Streaming Protocol (RTSP). The master device acts as an RTSP server for the slaves, which are RTSP clients. The "audio information" in the transfer message is an RTSP session URL with a range= parameter indicating the current playback time (e.g., rtsp://server.example.com/audio.mp3/trackID=123?range=npt=30-). To transfer the master role, the current master sends a proprietary transfer message containing this RTSP URL to the chosen slave. The new slave then issues an RTSP PLAY command to the original audio source using the provided URL and time offset and begins acting as the new RTSP server for the other slaves.

3. NTP Synchronization with Master Role Election: The core synchronization mechanism of the '001 patent is augmented by the Network Time Protocol (NTP). All devices in the synchrony group are clients of a common external NTP server, ensuring they share a highly accurate wall-clock time. The audio stream itself contains presentation timestamps relative to this NTP time. The role of the master is primarily to distribute the playlist and handle user commands. If the master fails, a slave can take over because all devices already share a common, authoritative time reference. The transfer message in this case does not need to contain detailed timing information, but rather the high-level state (playlist URI, track index, and a "start playing at NTP timestamp T" command), simplifying the handover. The new master is chosen via a simple election protocol (e.g., lowest IP address) triggered by the loss of the master's keep-alive signal.