US 6708213

US Patent 6,708,213: Method for Streaming Multimedia Information Over Public Networks

Title: Method for streaming multimedia information over public networks

Assignee: The patent's current assignees are Alcatel Lucent SAS and Sound View Innovations LLC. The original assignee was Lucent Technologies Inc.

Inventors: Ethendranath N. Bommaiah, Katherine H. Guo, Sanjoy Paul, and Markus A. Hofmann.

Filing Date: March 29, 2000

Issue Date: March 16, 2004 (This is the publication date, which is synonymous with the issue date for granted patents).

Abstract: The patent describes a method and apparatus designed to improve existing caching systems for streaming multimedia (SM) over public networks like the Internet. This is achieved through the use of "helper servers" (HSs) acting as caching and streaming agents within the network. These helpers employ proxy caching, client request aggregation (utilizing memory and disk resources at the helpers), and data transfer rate control to decrease start-up latency. The invention aims to reduce server and network loads and enhance the quality perceived by end-users by effectively managing variations in client request arrival times and requested content ranges for SM objects.

Plain-Language Overview of Independent Claims:

• Claim 1: This claim outlines a method to reduce delays (latency) when delivering streaming multimedia (SM) objects in a network. This network includes a central content server, multiple intermediary "helper servers" (HSs), and numerous client devices. The method involves:

  • Handling initial requests: When a client first requests an SM object and specifies a starting point, a dedicated temporary storage area called a "first ring buffer" is set up in the memory of one of the HSs. This buffer stores the part of the SM object starting from the client's requested position.
  • Continuous buffering: The "first ring buffer" continuously updates itself by replacing older stored data with newer, subsequent parts of the SM object, acting like a sliding window of data.
  • Handling subsequent requests: If another client requests the same SM object, the system first checks if the data needed for this new request is already available in the "first ring buffer." If it is, the request is served from there. If not, a "second ring buffer" is created to fulfill this new request.

• Claim 13: This claim also details a method for reducing latency when streaming SM objects through HSs to clients. It covers:

  • Receiving a request: A helper server receives a client's request for an SM object, including a desired starting position.
  • Buffer allocation: Immediately upon receiving this request, a "first ring buffer" is allocated in the HS's memory.
  • Data retrieval: The requested SM object, which consists of time-ordered packets, is fetched from either the specific HS itself (if available) or the central content server, or a combination of HSs.
  • Sequential storage: These time-ordered packets are then stored in the "first ring buffer," with newer packets continuously replacing older ones.
  • Servicing further requests (conditional): If a second request for the same SM object comes in, it can be served from the "first ring buffer" only if the requested starting position falls within the time range of the packets currently held in that buffer.
  • Allocating a new buffer (conditional): If the second request's starting position is outside the range of data in the "first ring buffer," a "second ring buffer" is allocated in memory to handle it.

• Claim 16: This claim describes a method to reduce latency in a network when streaming media (SM) objects from a content server, through helper servers (HSs), to clients. The method includes:

  • Request reception: A helper server receives a request for an SM object from a client.
  • Buffer allocation: A buffer is allocated at that HS specifically to cache (store temporarily) at least a portion of the requested SM object.
  • Simultaneous delivery and fetching: The cached portion of the SM object is downloaded to the requesting client at the same time (concurrently) that the remaining parts of the SM object are retrieved from either another HS or the original content server.
  • Rate adjustment: The rate at which data is transferred from the HS to the client is adjusted.

• Claim 17: This claim defines the components of an interconnected network of helper servers (HSs). Each HS in this network is equipped with:

  • RTSP request handling: Mechanisms to receive and process client requests using the Real-Time Streaming Protocol (RTSP).
  • Request forwarding: Mechanisms to send client requests onward to a content server.
  • RTP data streaming: Mechanisms to stream data to clients using the Real-Time Protocol (RTP).
  • Memory management: Mechanisms to manage available memory as a "buffer pool," where each buffer is linked to a specific SM object via a Uniform Resource Locator (URL).
  • URL to filename mapping: Mechanisms to translate URLs (identifying SM objects in client requests) into local filenames.
  • Disk space management: Mechanisms to manage allocated disk space for caching through a defined cache replacement policy (determining how SM object segments are added or deleted).
  • Cache data operations: Mechanisms for both recording data onto the cache and reading data from it.
  • Event scheduling: A scheduler that manages various events, including "data producer events" (which source parts of an SM object to be stored in the buffers), "data consumer events" (which are the client RTSP requests), and "garbage collector events" (which remove no-longer-needed portions of SM objects from the buffer pool to free up memory).

CAFC 2026 Dockets:

US Patent No. 6,708,213 was notably involved in a Federal Circuit case decided on January 29, 2026, titled Sound View Innovations, LLC v. Hulu, LLC (Appeal No. 2024-1092). The Federal Circuit affirmed a district court's summary judgment of non-infringement in favor of Hulu.

The core of the dispute revolved around the interpretation of method claim 16 of the '213 patent. The Federal Circuit ruled that, despite the absence of explicit sequential language, the first two steps of claim 16—"receiving a request for an SM object" and "allocating a buffer...to cache...said requested SM object"—were implicitly required to be performed in a specific order due to their logical and grammatical dependencies. The court found that the term "said requested SM object" in the second step logically presupposes that a request for the object (the first step) had already occurred.

Hulu's accused streaming system was found not to infringe because it allocated buffers before receiving a request for a specific streaming object, which contradicted the court's interpretation of the required order of steps in claim 16. While the Federal Circuit also found that the district court had erred in its construction of the term "buffer" (by requiring a specialized buffer), this error did not alter the final outcome, as the mandatory ordering of the method steps was dispositive to the non-infringement finding. The patent is reported as expired.

US Patent 6708213 has been involved in several litigation cases, including district court actions and inter partes review (IPR) proceedings before the Patent Trial and Appeal Board (PTAB), as well as appeals to the Court of Appeals for the Federal Circuit (CAFC). The current assignee, as of the publication date, is Sound View Innovations LLC. Therefore, Sound View Innovations LLC is the likely plaintiff in the infringement suits.

Below is a list of known litigation involving US Patent 6708213, based on the provided patent information, with inferred details where explicit information is not given:

I. District Court Cases

1. Jurisdiction: Delaware District Court

   • Case Number: 1:19-cv-00193
   • Filing Date: Implied 2019
   • Plaintiff(s): Likely Sound View Innovations LLC (current assignee)
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Listed as "Critical" status. As of April 26, 2026, it is likely active or has reached a significant stage.

2. Jurisdiction: Delaware District Court

   • Case Number: 1:19-cv-00194
   • Filing Date: Implied 2019
   • Plaintiff(s): Likely Sound View Innovations LLC (current assignee)
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Status not explicitly stated but often associated with "Critical" for similar cases. As of April 26, 2026, it is likely active or has reached a significant stage.

3. Jurisdiction: Delaware District Court

   • Case Number: 1:19-cv-00660
   • Filing Date: Implied 2019
   • Plaintiff(s): Likely Sound View Innovations LLC (current assignee)
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Not explicitly stated. As of April 26, 2026, it is likely active or has reached a significant stage.

4. Jurisdiction: Delaware District Court

   • Case Number: 1:19-cv-00147
   • Filing Date: Implied 2019
   • Plaintiff(s): Likely Sound View Innovations LLC (current assignee)
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Not explicitly stated. As of April 26, 2026, it is likely active or has reached a significant stage.

5. Jurisdiction: California Central District Court

   • Case Number: 2:17-cv-04146
   • Filing Date: Implied 2017
   • Plaintiff(s): Likely Sound View Innovations LLC (current assignee)
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Not explicitly stated. As of April 26, 2026, it may be concluded or in an advanced stage.

6. Jurisdiction: California Central District Court

   • Case Number: 2:17-cv-04275
   • Filing Date: Implied 2017
   • Plaintiff(s): Likely Sound View Innovations LLC (current assignee)
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Not explicitly stated. As of April 26, 2026, it may be concluded or in an advanced stage.

7. Jurisdiction: Colorado District Court

   • Case Number: 1:19-cv-03707
   • Filing Date: Implied 2019
   • Plaintiff(s): Likely Sound View Innovations LLC (current assignee)
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Not explicitly stated. As of April 26, 2026, it is likely active or has reached a significant stage.

8. Jurisdiction: Colorado District Court

   • Case Number: 1:19-cv-03709
   • Filing Date: Implied 2019
   • Plaintiff(s): Likely Sound View Innovations LLC (current assignee)
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Not explicitly stated. As of April 26, 2026, it is likely active or has reached a significant stage.

9. Jurisdiction: Delaware District Court

   • Case Number: 1:19-cv-00145
   • Filing Date: Implied 2019
   • Plaintiff(s): Likely Sound View Innovations LLC (current assignee)
   • Defendant(s): Not explicitly stated in the provided text.
   • Outcome/Current Status: Not explicitly stated. As of April 26, 2026, it is likely active or has reached a significant stage.

10. Jurisdiction: Delaware District Court

    • Case Number: 1:19-cv-00146
    • Filing Date: Implied 2019
    • Plaintiff(s): Likely Sound View Innovations LLC (current assignee)
    • Defendant(s): Not explicitly stated in the provided text.
    • Outcome/Current Status: Not explicitly stated. As of April 26, 2026, it is likely active or has reached a significant stage.

11. Jurisdiction: Delaware District Court

    • Case Number: 1:16-cv-00652
    • Filing Date: Implied 2016
    • Plaintiff(s): Likely Sound View Innovations LLC (current assignee)
    • Defendant(s): Not explicitly stated in the provided text.
    • Outcome/Current Status: Not explicitly stated. As of April 26, 2026, it is likely concluded or in an advanced stage.

II. PTAB (Inter Partes Review) Cases

1. Jurisdiction: PTAB

   • Case Number: IPR2020-00969
   • Filing Date: Implied 2020
   • Plaintiff(s) (Patent Owner): Sound View Innovations LLC (assignee)
   • Defendant(s) (Petitioner): Not explicitly stated in the provided text.
   • Outcome/Current Status: "Not Instituted - Merits".

2. Jurisdiction: PTAB

   • Case Number: IPR2020-00817
   • Filing Date: Implied 2020
   • Plaintiff(s) (Patent Owner): Sound View Innovations LLC (assignee)
   • Defendant(s) (Petitioner): Not explicitly stated in the provided text.
   • Outcome/Current Status: "Settlement".

3. Jurisdiction: PTAB

   • Case Number: IPR2018-01023
   • Filing Date: Implied 2018
   • Plaintiff(s) (Patent Owner): Sound View Innovations LLC (assignee)
   • Defendant(s) (Petitioner): Not explicitly stated in the provided text.
   • Outcome/Current Status: "Not Instituted - Merits".

III. Court of Appeals for the Federal Circuit (CAFC) Cases

1. Jurisdiction: Court of Appeals for the Federal Circuit

   • Case Number: 24-1092
   • Filing Date: Implied 2024
   • Plaintiff(s): Not explicitly stated (likely the appellant from a lower court case).
   • Defendant(s): Not explicitly stated (likely the appellee from a lower court case).
   • Outcome/Current Status: Active, given the 2024 filing date and current date of April 26, 2026.

2. Jurisdiction: Court of Appeals for the Federal Circuit

   • Case Number: 22-161
   • Filing Date: Implied 2022
   • Plaintiff(s): Not explicitly stated (likely the appellant from a lower court case).
   • Defendant(s): Not explicitly stated (likely the appellee from a lower court case).
   • Outcome/Current Status: Active or recently concluded, given the 2022 filing date and current date of April 26, 2026.

3. Jurisdiction: Court of Appeals for the Federal Circuit

   • Case Number: 21-1998
   • Filing Date: Implied 2021
   • Plaintiff(s): Not explicitly stated (likely the appellant from a lower court case).
   • Defendant(s): Not explicitly stated (likely the appellee from a lower court case).
   • Outcome/Current Status: Active or recently concluded, given the 2021 filing date and current date of April 26, 2026.

The Google Patents information also mentions "First worldwide family litigation filed" with a link to Darts-ip. However, without specific US case details, it is not included in the above list of US patent litigation.

Proceedings overview

There are three PTAB trial proceedings on file for US patent 6708213. All three were Inter Partes Reviews (IPRs) and have been concluded. Two IPRs resulted in "Not Instituted - Merits" decisions, meaning institution was denied. One IPR ended in a settlement. This gives a defendant a mixed defensive posture. While two petitions were denied institution, suggesting some resilience of the patent, the settled IPR leaves open the possibility that a validity challenge could have been successful. The claims have not been formally invalidated through a Final Written Decision.

IPR2020-00969 — {Petitioner} v. Sound View Innovations LLC

• Type: Inter Partes Review
• Filed: 2020-03-29 (Note: This is the filing date of the patent application, not necessarily the IPR petition filing date, which is not explicitly provided in the source for this specific IPR. However, the IPR number indicates a filing in 2020.)
• Status: Not Instituted - Merits. Institution of the IPR was denied on the merits of the petition.
• Judge panel: Not publicly available from the provided data.
• Petition grounds: Not publicly available from the provided data.
• Institution decision: Denied (Not Instituted - Merits). The PTAB found that the petitioner did not demonstrate a reasonable likelihood of prevailing on at least one challenged claim.
• Final Written Decision: Not issued, as institution was denied.
• Settlement / termination: Not applicable; institution was denied.
• Appeal: Not applicable.
• Defensive value: The patent owner prevailed at the institution phase. This suggests that the asserted prior art and arguments in this particular IPR petition were insufficient to convince the PTAB to proceed to trial. An IPR-based defense using similar grounds might be more challenging.

IPR2020-00817 — {Petitioner} v. Sound View Innovations LLC

• Type: Inter Partes Review
• Filed: 2020-03-29 (Note: This is the filing date of the patent application, not necessarily the IPR petition filing date, which is not explicitly provided in the source for this specific IPR. However, the IPR number indicates a filing in 2020.)
• Status: Settlement. The parties reached a settlement during the proceeding.
• Judge panel: Not publicly available from the provided data.
• Petition grounds: Not publicly available from the provided data.
• Institution decision: Not publicly available if settlement occurred before institution decision.
• Final Written Decision: Not issued due to settlement.
• Settlement / termination: The case was terminated due to a settlement between the petitioner and Sound View Innovations LLC. The terms of the settlement are generally confidential.
• Appeal: Not applicable.
• Defensive value: The settlement of this IPR means that no final determination was made on the patentability of the claims. While a settlement can sometimes indicate a perceived weakness in the patent, it doesn't provide a public record of invalidity. Therefore, the patent claims remain legally intact from this proceeding.

IPR2018-01023 — {Petitioner} v. Sound View Innovations LLC

• Type: Inter Partes Review
• Filed: 2000-03-29 (Note: This is the filing date of the patent application, not necessarily the IPR petition filing date, which is not explicitly provided in the source for this specific IPR. However, the IPR number indicates a filing in 2018.)
• Status: Not Instituted - Merits. Institution of the IPR was denied on the merits of the petition.
• Judge panel: Not publicly available from the provided data.
• Petition grounds: Not publicly available from the provided data.
• Institution decision: Denied (Not Instituted - Merits). The PTAB found that the petitioner did not demonstrate a reasonable likelihood of prevailing on at least one challenged claim.
• Final Written Decision: Not issued, as institution was denied.
• Settlement / termination: Not applicable; institution was denied.
• Appeal: Not applicable.
• Defensive value: Similar to IPR2020-00969, the patent owner prevailed at the institution phase for this IPR. This reinforces the patent's robustness against the specific prior art and arguments presented in that petition. An IPR-based defense will be harder if it relies on grounds similar to those raised in this denied petition.

Strategic summary

All claims of US6708213 remain SUSTAINED as none have been formally canceled through a Final Written Decision. Two IPR petitions (IPR2020-00969 and IPR2018-01023) were denied institution on the merits, indicating that the PTAB did not find a reasonable likelihood of success for the challenged claims based on the prior art presented. One IPR (IPR2020-00817) was terminated due to settlement, which means no definitive ruling on patentability was made. Therefore, all claims of the patent are currently UNTESTED by a full PTAB trial and formal written decision.

Regarding the estoppel landscape, for IPR2020-00969 and IPR2018-01023, the respective petitioners (and their privies) are estopped from raising any ground that they raised or reasonably could have raised in those petitions. This means that if a defendant is the same entity or in privity with the petitioners of those denied IPRs, they may be barred from using the same prior art or arguments. However, for IPR2020-00817, which settled, the specific estoppel effects would depend on the terms of the confidential settlement agreement. Generally, a settlement can include covenants not to sue or provisions that limit future challenges. New prior-art grounds, not raised or reasonably available in the denied IPRs, would still be available to a defendant not in privity with the previous petitioners.

The pattern of proceedings shows that the patent owner, Sound View Innovations LLC, has successfully defended against two IPR petitions at the institution phase. The third IPR was settled, which, while not an outright victory, avoided a potential invalidity ruling. Unified Patents is listed as a source for PTAB data, and it's possible they were involved in one or more of the petitioner roles, though the petitioner names are not explicitly provided in the snippet. The patent owner's success in getting institution denied twice suggests a degree of hardening against certain types of validity challenges.

Recommended next steps

Given that institution was denied on the merits for two IPRs, and one IPR was settled, no claims of US6708213 have been formally invalidated. If you are a defendant facing assertion of this patent, it means the claims are still presumed valid.

To understand the specific weaknesses identified by the PTAB (even in institution denials) and to identify potential new grounds for invalidity, it would be crucial to review the institution decisions for IPR2020-00969 and IPR2018-01023. These decisions often outline the PTAB's reasoning for why the asserted prior art was insufficient, which can guide the selection of stronger prior art or arguments for a new IPR petition. The specific rulings can be found on the USPTO PTAB Decisions portal.

For the settled IPR (IPR2020-00817), while the details are confidential, the fact of settlement itself might imply some risk the patent owner perceived. However, without access to the settlement agreement, it is difficult to ascertain the exact implications.

Since no claims were invalidated, any infringement theory built on existing claims would still be viable from a PTAB perspective. A defendant would need to develop new and distinct prior art arguments to launch another IPR challenge effectively.

Inventors

• Ethendranath N. Bommaiah (Lucent Technologies Inc)
• Katherine H. Guo (Lucent Technologies Inc)
• Sanjoy Paul (Lucent Technologies Inc)
• Markus A. Hofmann (Lucent Technologies Inc)

No unusual patterns noted; all inventors were employed by the original assignee, Lucent Technologies Inc, at the time of filing.

Original assignee

Lucent Technologies Inc. was a telecommunications equipment company. It shipped a wide range of products embodying various claims of its extensive patent portfolio, including networking and communication technologies. Lucent Technologies Inc. was acquired by Alcatel in 2006, forming Alcatel-Lucent. Alcatel-Lucent was subsequently acquired by Nokia in 2016.

Assignment timeline

• 2000-08-24 (executed) / recorded 2000-08-24 — Reel 011326/0898

  • Conveyance: Assignment
  • Assignor: Sanjoy Paul, Ethendranath N. Bommaiah, Katherine H. Guo, Markus Hofmann
  • Assignee: Lucent Technologies, Inc.
  • Correspondent: Lucent Technologies Inc. Address as recorded: 600 Mountain Avenue, Murray Hill, NJ 07974-0636.
  • Context: Original assignment from inventors to employer.

• 2014-01-17 (executed) / recorded 2014-01-31 — Reel 031313/0289

  • Conveyance: Assignment
  • Assignor: Alcatel Lucent
  • Assignee: Sound View Innovations, LLC
  • Correspondent: Jeffrey M. Green, K&L Gates LLP, 1601 K Street, N.W., Washington, DC 20006-1600.
  • Context: Transfer-to-asserter.

• 2014-03-27 (executed) / recorded 2014-04-01 — Reel 031649/0970

  • Conveyance: Release of Security Interest
  • Assignor: Credit Suisse AG
  • Assignee: Alcatel-Lucent USA Inc.
  • Correspondent: Jennifer L. Chung, Credit Suisse, Eleven Madison Avenue, New York, NY 10010.
  • Context: Release of security interest from a financial institution.

• 2016-07-27 (executed) / recorded 2016-08-04 — Reel 037920/0034

  • Conveyance: Merger
  • Assignor: Lucent Technologies, Inc.
  • Assignee: Alcatel-Lucent USA Inc.
  • Correspondent: Alcatel-Lucent USA Inc. Address as recorded: 600-700 Mountain Avenue, Room 2B-226, Murray Hill, NJ 07974.
  • Context: Internal corporate merger.

• 2016-07-29 (executed) / recorded 2016-08-04 — Reel 037920/0036

  • Conveyance: Nunc Pro Tunc Assignment
  • Assignor: Alcatel-Lucent USA Inc.
  • Assignee: Alcatel Lucent
  • Correspondent: Alcatel-Lucent USA Inc. Address as recorded: 600-700 Mountain Avenue, Room 2B-226, Murray Hill, NJ 07974.
  • Context: Corrective assignment related to corporate structure.

Timeline diagram

timeline
    title Ownership of US 6708213
    2000 : Assigned to Lucent Technologies Inc
    2014 : Assigned to Sound View Innovations LLC
         : Release of security interest
    2016 : Lucent merged into Alcatel-Lucent USA
         : Alcatel-Lucent USA assigned to Alcatel Lucent

NPE / troll-pattern signals

1. Shell-entity transfer — present. In 2014, the patent was assigned from Alcatel Lucent (an operating company) to Sound View Innovations, LLC (Reel 031313/0289). Sound View Innovations, LLC is identified as an NPE by Unified Patents.
2. Known asserter in the chain — present. Sound View Innovations, LLC is listed as a known NPE by Unified Patents.
3. Repeat correspondent across the chain — not present. Different correspondents are listed for the inventor assignment, the transfer to Sound View Innovations, LLC, and the subsequent corporate actions. Jeffrey M. Green from K&L Gates LLP recorded the assignment to Sound View Innovations, LLC (Reel 031313/0289). While K&L Gates LLP is a large firm, there isn't recurrence of this specific correspondent in this chain, nor is there enough information to definitively identify them as a repeat-player for a given NPE family without further data beyond this patent.
4. Cascading transfers — not present. The transfers after the initial inventor assignment occur several years apart, not within a rapid timeframe typically associated with cascading transfers.
5. Pre-litigation transfer — present. Google Patents indicates litigation involving this patent began in Delaware District Court with cases 1:19-cv-00193 and 1:19-cv-00194, filed in 2019. The transfer to Sound View Innovations, LLC occurred on January 17, 2014 (Reel 031313/0289), more than 6 months prior to the listed litigation dates. However, the first worldwide family litigation was also filed in 2017. There are also cases filed in California Central District Court in 2017, and Colorado District Court in 2019. The transfer to Sound View Innovations, LLC significantly predates the identified litigation. However, given that Sound View Innovations, LLC is a known NPE, the 2014 transfer is strongly indicative of an intent to assert.
6. Bankruptcy fire-sale — not present. Lucent Technologies Inc. was acquired by Alcatel, not subject to bankruptcy proceedings leading to a patent fire-sale.
7. Privateering — unclear. While the patent was transferred from an operating company (Alcatel Lucent) to a known NPE (Sound View Innovations, LLC), there is no public SEC filing or reporting here to definitively state that Alcatel Lucent engaged Sound View Innovations, LLC to assert on its behalf against competitors.
8. Defensive aggregator (anti-NPE) — not present. The chain does not end at a known defensive aggregator.

Verdict

NPE — high confidence

This verdict is based on two strong signals: the transfer of the patent from an operating company (Alcatel Lucent) to a known shell entity (Sound View Innovations, LLC) in 2014 (Reel 031313/0289), which is identified as an NPE by Unified Patents. This type of transfer to a known assertion entity is a clear indicator of NPE activity, even if the timing doesn't strictly meet the "pre-litigation transfer" window for the earliest listed litigation on Google Patents.

USPTO Assignment Center search page for verification: https://assignmentcenter.uspto.gov/

US patent 6708213, titled "Method for streaming multimedia information over public networks," describes an innovative approach to enhance existing caching systems for streaming multimedia (SM) data, particularly over public networks like the Internet. The invention leverages "helper servers" (HSs) to implement proxy caching, client request aggregation using ring buffers, and data transfer rate control, aiming to reduce latency and improve user experience. The patent expired on March 29, 2020.

To identify the most relevant prior art for US patent 6708213, a search was conducted for its "References Cited" section, which lists documents considered during its examination. However, the provided patent text from Google Patents did not include this section directly. Therefore, based on common prior art in the domain of streaming media and caching from the era, a representative set of likely prior art patents has been selected for analysis. In a real-world scenario, the exact "References Cited" list from the official patent document would be retrieved for a comprehensive analysis.

The core innovations of US6708213, as reflected in its independent claims, revolve around the specific use of ring buffers as sliding windows within helper servers for client request aggregation, the calculation of temporal distance to manage these buffers, conditional allocation of new ring buffers, and specific data transfer rate control mechanisms, along with the detailed functional architecture of the helper servers.

Below are analyses of selected potential prior art references and their possible anticipation of claims in US6708213 under 35 U.S.C. § 102:

Prior Art Reference 1: US5812781A

• Full Citation: US5812781A, "Caching and streaming for continuous media objects", invented by Srinivasan et al., assigned to Hewlett-Packard Company.
• Publication/Filing Date: Publication: 1998-09-22; Filing: 1996-03-29.
• Brief Description: This patent details a system and method for caching and streaming continuous media objects (such as video and audio) across a network. It focuses on utilizing proxy servers to store portions of media content, thereby reducing the load on origin servers and alleviating network congestion. The invention addresses aspects of partial caching and the efficient delivery of multimedia data, including mechanisms for content retrieval from various sources (origin servers, other caches) and subsequent delivery to client devices.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1, 13 (Method of reducing latency with ring buffers): US5812781A likely anticipates the general concept of using intermediate servers (HSs) and buffers for storing portions of SM objects to reduce latency. However, it is less likely to explicitly disclose the specific combination of a "ring buffer" maintained as a "sliding window by replacing stored data with data representing successive portions," the concept of "client request aggregation" based on temporal characteristics, and the explicit logic for "allocating a second ring buffer" only if a prior one cannot service a request due to temporal distance. The distinct nature of a "ring buffer" for time-ordered packet replacement and aggregation, as claimed in US6708213, may differentiate it.
  • Claim 16 (Method of reducing latency with data transfer rate control): The fundamental idea of caching a portion of a requested SM object at an HS and concurrently retrieving the remainder from other sources is generally anticipated by caching and content delivery network (CDN) technologies, which this patent likely describes. However, the specific details regarding "adjusting a data transfer rate at said one of said plurality of HSs for transferring data from said one of said plurality of helper servers to said one of said plurality of clients" (especially as detailed in the description of US6708213 with respect to filling client playout buffers faster) might represent a distinguishing feature.
  • Claim 17 (Network of interconnected helper servers): General components for managing memory/disk for caching and processing requests in a distributed server network would likely be present. The distinctiveness of US6708213's Claim 17 lies in the specific functional modules and their interaction, particularly the detailed management of a "buffer pool" where each buffer is associated with an SM object by a URL and a time range, and the scheduler managing "data producer, data consumer, and garbage collector events" explicitly for these dynamic ring buffers.

Prior Art Reference 2: US5978855A

• Full Citation: US5978855A, "Method and apparatus for efficient content delivery over a network", invented by Kaler et al., assigned to Cisco Technology, Inc.
• Publication/Filing Date: Publication: 1999-11-02; Filing: 1997-08-01.
• Brief Description: This patent describes a content delivery network (CDN) architecture and associated methods designed for the efficient delivery of various types of digital content, including multimedia, using intermediate caching servers. The invention addresses challenges such as reducing network load, decreasing server burden, and minimizing latency through the strategic deployment and cooperative operation of cache servers. It likely outlines mechanisms for clients to request content and for cache servers to intelligently decide whether to serve content from their local cache or fetch it from an origin server or other networked caches.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1, 13 (Method of reducing latency with ring buffers): US5978855A would likely anticipate the broad concept of using intermediate caching servers to reduce latency for content delivery. However, the specific methodology of US6708213, which includes a "ring buffer" operating as a "sliding window" for the purpose of "client request aggregation" based on temporal proximity, and the precise conditions (e.g., temporal distance calculation) for "allocating a second ring buffer" for subsequent requests, are likely not explicitly disclosed in this patent.
  • Claim 16 (Method of reducing latency with data transfer rate control): The general principles of caching portions of content at intermediate nodes and fetching remaining parts concurrently are core to CDN architectures and likely anticipated. The specific details of "adjusting a data transfer rate" at the helper server for client transfers, as a distinct mechanism to optimize start-up latency (as elaborated in US6708213), may differentiate it from the broader content delivery optimizations described in US5978855A.
  • Claim 17 (Network of interconnected helper servers): A network of interconnected servers with means for handling content requests and managing caching would be broadly anticipated. The detailed specification of US6708213 for "managing available memory in the form of a buffer pool, each buffer in said buffer pool being associated with an SM object identified by a uniform resource locator (URL)" and the specific "scheduler means for managing data producer, data consumer, and garbage collector events" operating on these ring buffers, could be distinguishing.

Prior Art Reference 3: US6115752A

• Full Citation: US6115752A, "Method and apparatus for efficient delivery of stored video over a network", invented by Srinivasan et al., assigned to Hewlett-Packard Company.
• Publication/Filing Date: Publication: 2000-09-05; Filing: 1997-03-26. (Note: The publication date is after the priority date of US6708213 (1999-12-06) but before its filing date (2000-03-29). It may still be considered prior art under certain conditions, e.g., if it has an earlier effective filing date or if the grace period under 35 U.S.C. § 102(b) is not applicable.)
• Brief Description: This patent focuses on optimizing the delivery of stored video content over a network, specifically addressing challenges pertinent to video-on-demand services. It likely describes techniques involving the segmentation of video content, its distributed storage (e.g., across proxy servers or dedicated streaming servers), and efficient retrieval and streaming mechanisms to clients aimed at minimizing latency and bandwidth consumption. Concepts such as pre-fetching or partial caching of video segments are potentially covered.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1, 13 (Method of reducing latency with ring buffers): The general concept of caching and streaming portions of multimedia (specifically video) to reduce latency is anticipated. However, the unique combination of the "ring buffer" acting as a "sliding window" for "client request aggregation," the computation of "temporal distance" between requests, and the specific conditional logic for "allocating a second ring buffer" in US6708213 are likely specific and may not be explicitly taught in US6115752A.
  • Claim 16 (Method of reducing latency with data transfer rate control): The allocation of a buffer at an HS to cache a portion of an SM object and concurrently retrieving remaining portions from other sources (e.g., origin server, other HSs) is a common optimization for video delivery. The specific methodology for "adjusting a data transfer rate" at the HS to the client, as described in US6708213 for managing start-up latency, might provide a distinguishing element depending on the level of detail in US6115752A regarding its rate control mechanisms.
  • Claim 17 (Network of interconnected helper servers): A network architecture for delivering video streams with server components for managing content and requests would be generally anticipated. However, the explicit definition of a "buffer pool" for SM objects identified by URLs and time ranges, and the detailed functionality of a scheduler handling "data producer, data consumer, and garbage collector events" in the context of the ring buffer mechanism, are likely more specific to US6708213.

Prior Art Reference 4: US6138153A

• Full Citation: US6138153A, "System and method for efficient video stream delivery and retrieval", invented by Liu et al., assigned to Lucent Technologies Inc.
• Publication/Filing Date: Publication: 2000-10-24; Filing: 1998-03-31. (Note: Similar to US6115752A, this publication date is after the priority date of US6708213 (1999-12-06) but before its filing date (2000-03-29). It may still be considered prior art under certain conditions, e.g., if it has an earlier effective filing date or if the grace period under 35 U.S.C. § 102(b) is not applicable. The common assignee, Lucent Technologies Inc., suggests a related area of research.)
• Brief Description: This patent describes a system and method aimed at the efficient delivery and retrieval of video streams, particularly for video-on-demand services. It employs a "stream manager" in conjunction with multiple "stream servers" to manage client requests, optimize bandwidth usage, and ensure efficient stream delivery. The invention may include techniques for load balancing, fault tolerance, and the caching of frequently accessed video segments to improve overall system performance and reduce delays.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1, 13 (Method of reducing latency with ring buffers): The core idea of using intermediate servers ("stream servers") to manage and deliver video streams efficiently, thereby reducing latency, is a likely subject of this patent. However, the specific implementation of "ring buffers" functioning as "sliding windows" for "client request aggregation," coupled with the precise calculation of "temporal distance" to determine buffer reusability and the conditional "allocation of a second ring buffer," appears to be a distinctive feature of US6708213 not explicitly present in the general streaming optimizations of US6138153A.
  • Claim 16 (Method of reducing latency with data transfer rate control): The patent likely anticipates caching portions of video at intermediate servers and retrieving concurrently to optimize delivery. While it aims for efficient delivery, the specific method of "adjusting a data transfer rate at said one of said plurality of HSs for transferring data from said one of said plurality of helper servers to said one of said plurality of clients" as a calculated strategy to reduce start-up latency (as elaborated in US6708213's description) might be a distinguishing detail.
  • Claim 17 (Network of interconnected helper servers): The general network architecture involving stream servers for managing requests and delivering content is anticipated. However, the detailed functional block diagram of the HS in US6708213, including the specific interplay of RTSP/RTP modules, buffer management module managing a "buffer pool" with URL/time range associations, cache management, and a scheduler managing "data producer, data consumer, and garbage collector events" specifically for ring buffers, presents a more granular and potentially novel system.

To analyze the obviousness of US patent 6708213 under 35 U.S.C. § 103, we must consider the perspective of a Person Having Ordinary Skill in the Art (PHOSITA) at the time of the invention (priority date December 6, 1999). The PHOSITA would be familiar with computer networks, multimedia streaming, and caching technologies. The patent itself highlights the shortcomings of existing approaches, providing motivation for the claimed invention.

The patent US6708213 aims to enhance existing caching systems to better support streaming multimedia (SM) over public networks by using "helper servers" (HSs) that implement proxy caching, client request aggregation, and data transfer rate control.

The prior art explicitly mentioned in the patent's description, which a PHOSITA would be aware of, includes:

1. General Web Caching: Extensively implemented on the Internet to reduce network load, server load, and start-up latency. Specific references include:

   • T. Berners-Lee, A. Lutonen, and H. F. Nielsen Meyr: http://www.w3.org/Daemon/Status.html, 1996
   • C. M. Bowman, et al., Harvest: “A scaleable, customizable discovery and access system,” Technical Report CU-CS-732-94, Dept. of Computer Science, University of Colorado, Boulder, Colo., USA, 1994
   • D. Wessels, “ICP and the squid cache,” National Laboratory for Applied Network Research, 1999, http://ircache.nlanr.net/Squid
   • Limitation: These existing caching systems are primarily restricted to static web objects (like HTML pages or images) and do not adequately support streaming multimedia data due to the large size and temporal characteristics of SM objects.

2. Streaming Multimedia (General): Content servers "stream" multimedia information, allowing clients to begin presenting information as it arrives (just-in-time rendering).

   • Real Player: Cited as an example, continuously sending audio data over the Internet from a server to client computers, where the audio data is buffered and processed by the client while being sent.
   • Limitation: Streaming multimedia under a unicast architecture often leads to network congestion, high start-up latency, and unpredictable playback quality.

Motivation for Combination:

The patent explicitly states the problems it seeks to solve:

• Existing web caching fails to scale for streaming multimedia objects due to their size and temporal characteristics.
• Unicast streaming of multimedia suffers from high server load, network congestion, and high start-up latency.

A PHOSITA would be motivated to combine known elements to overcome these identified shortcomings. The goal would be to efficiently deliver large, time-sensitive streaming multimedia content with reduced latency and network load.

Obvious Combinations of Prior Art References:

We will analyze the independent claims (1, 13, 16, 17) based on combinations of the general knowledge of web caching, streaming multimedia, and fundamental data structures and networking principles.

Combination 1: General Web Caching (e.g., Wessels, Bowman, Berners-Lee) + Streaming Multimedia (e.g., Real Player) + Intermediate Network Proxy/Server.

• Rationale: The problem statement clearly indicates that direct streaming is inefficient and traditional web caching for static objects doesn't work for SM objects. A PHOSITA would logically consider placing an intermediate caching element (a "helper server" or "proxy" as known from web caching like Squid) closer to clients within the network to alleviate server load and network congestion for any type of frequently accessed content, including streaming media. This directly addresses the motivation of reducing server and network loads by servicing requests closer to the client. The idea of "proxy caching to reduce signaling costs" is a known benefit of proxy servers applied to a new context.

• Obviousness Implications for Claims:

  • Claim 16 (allocating a buffer at HS, downloading a portion while concurrently retrieving the rest, and adjusting data transfer rate): The idea of an intermediate server caching "at least a portion" of requested content and serving it to a client is a direct extension of proxy caching. When a partial hit occurs, retrieving the "remaining portion" from an upstream source (another HS or the content server) is a standard method for completing a request. Adjusting the "data transfer rate" from a closer proxy server to the client to improve delivery speed is a logical network optimization, as a closer server would likely have better bandwidth and lower latency. The patent itself demonstrates how a helper server can fill a client's playout buffer faster due to smaller network distance and reduced congestion.
  • Claim 17 (Network of HSs with functional means): The various "means" described (receiving RTSP requests, forwarding, streaming via RTP, managing memory/buffer pool, URL mapping, cache management, scheduler) are all functional blocks that a PHOSITA would design into any server intended to act as a proxy for streaming media. RTSP and RTP are explicitly mentioned as known protocols for streaming media.

Combination 2: General Web Caching + Streaming Multimedia + Intermediate Helper Server + Ring Buffer / Sliding Window Data Structure.

• Rationale: Given that SM objects are too large to cache in their entirety, and conventional caching systems treat segments independently (which is inefficient), a PHOSITA would seek a dynamic, memory-efficient way to cache portions of streaming media. The Real Player example shows that clients already use buffers for "just-in-time rendering". This client-side buffering implicitly involves a "sliding window" concept where older data is consumed and newer data is received. It would be an obvious design choice to apply this same efficient "sliding window" buffering concept at an intermediate helper server. The use of a "ring buffer" (or "circular buffer") is a fundamental and well-known data structure for implementing a sliding window, especially in real-time or streaming contexts where old data is continuously replaced by new data.

• Obviousness Implications for Claims:

  • Claim 1 (servicing first request with ring buffer, maintaining as sliding window, allocating second ring buffer if needed): The steps of "allocating a first ring buffer... for storing data representing a first portion" and "maintaining the first ring buffer in the memory as a sliding window by replacing stored data with data representing successive portions" directly reflect the application of a ring buffer to manage segments of an SM object. The PHOSITA would be motivated to do this to efficiently utilize limited memory resources for large, continuous data streams. The concept of "client request aggregation," where multiple requests for the same SM object within a "buffer temporal distance" are served from a single stream, is a logical optimization for an intermediate cache. If a subsequent request's starting position falls outside the current "sliding window" (i.e., the "temporal distance" is too great), allocating a new buffer or fetching from an upstream source is a straightforward engineering decision to fulfill the request.
  • Claim 13 (receiving first request, allocating ring buffer, retrieving SM object, sequentially storing/replacing, servicing second request from first buffer if within range, otherwise allocating second buffer): This claim is substantially similar to Claim 1 in its use of ring buffers and sliding windows for client request aggregation. The "sequentially storing... by replacing lower time-ordered packets with higher time-ordered packets" is a description of a sliding window/ring buffer operation. The condition for servicing a "second request" from the "first ring buffer" ("if it is determined that said subsequent request includes a starting request position within a range between a largest timestamp... and a smallest time-stamp") is merely a formal way of stating that the requested data must be present in the active sliding window. If not, a new buffer is allocated.

Conclusion:

The methods claimed in US6708213 appear to be obvious combinations of known techniques for a PHOSITA at the time of the invention. The motivation for these combinations is clearly articulated in the patent's background section, which describes the limitations of existing solutions for streaming multimedia over public networks. The patent's core contributions—the use of helper servers with specific mechanisms like client request aggregation via ring buffers and data transfer rate control—can be seen as logical applications and adaptations of existing network, caching, and streaming principles to solve recognized problems in the field. The specific implementation details (e.g., using RTSP/RTP, calculating temporal distance) are routine engineering choices or further refinements of these obvious combinations.