US 9001774

Here is a concise summary of US patent 9001774:

US Patent 9001774: System and method for channel estimation in a delay diversity wireless communication system

• Title: System and method for channel estimation in a delay diversity wireless communication system
• Assignee: Unwired Planet International Ltd (current assignee as of September 8, 2017). The original assignee was [Samsung Electronics Co Ltd](/litigations/by-plaintiff/Samsung%20Electronics%20Co%20Ltd) when the application was filed.
• Inventors: Farooq Khan
• Filing Date: November 12, 2013
• Issue Date: April 7, 2015
• Abstract: The patent describes a method for controlling downlink transmissions to a subscriber station in an Orthogonal Frequency Division Multiplexing (OFDM) network. This method involves the subscriber station receiving first and second pilot signals from a base station's respective antennas, then estimating the channel based on these pilots. The subscriber station determines a set of OFDM symbol processing parameters (relative gains and delays for OFDM symbols transmitted from the antennas) based on this channel estimation and transmits these parameters back to the base station. The base station then uses these parameters to control its downlink transmissions.

Plain-Language Overview of Independent Claims:

• Independent Claim 1 (Base Station Method): This claim describes a method performed by a base station. The base station receives a signal from a subscriber station (an "uplink signal"). Based on this uplink signal, the base station determines a "processing parameter" which can include a time delay, a phase rotation, or a gain. This parameter is used for transmitting data over two antenna ports. The base station then transmits two pilot signals and two data symbols from these two antenna ports. Crucially, at least one of these transmitted data symbols is processed using the previously determined processing parameter.
• Independent Claim 6 (Subscriber Station Method): This claim describes a method performed by a subscriber station (receiver). The subscriber station receives a "processing parameter" (which can be a time delay, phase rotation, or gain) from the base station; this parameter was determined by the base station based on an uplink signal. The subscriber station also receives a first pilot signal, a second pilot signal, a first data symbol, and a second data symbol, all transmitted from two antenna ports. The core of the claim is that the subscriber station then demodulates both received data symbols using the received processing parameter, along with the received first and second pilot signals.

Litigation/Legal Status Note:
The patent US9001774B2 expired on March 27, 2026. The Google Patents record indicates an "Expired - Lifetime" legal status. While the patent itself notes a history of litigation in various courts up to 2022, no specific dockets for US9001774 in the CAFC for 2026 were found during this search.

Here is the known litigation involving US patent 9001774, based on the provided patent text from Google Patents:

1. US case filed in Court of Appeals for the Federal Circuit

• Plaintiff(s): Not explicitly stated in the provided text.
• Defendant(s): Not explicitly stated in the provided text.
• Jurisdiction: Court of Appeals for the Federal Circuit
• Case Number: 22-1925
• Filing Date: Not explicitly stated in the provided text.
• Outcome or Current Status: Critical

2. US case filed in Texas Eastern District Court

• Plaintiff(s): Not explicitly stated in the provided text.
• Defendant(s): Not explicitly stated in the provided text.
• Jurisdiction: Texas Eastern District Court
• Case Number: 2:19-cv-00066
• Filing Date: Not explicitly stated in the provided text.
• Outcome or Current Status: Litigation (status not further detailed)

3. PTAB case IPR2020-00642 filed (Not Instituted - Procedural)

• Plaintiff(s): Petitioner (details not explicitly stated)
• Defendant(s): Not explicitly stated in the provided text.
• Jurisdiction: PTAB
• Case Number: IPR2020-00642
• Filing Date: Not explicitly stated in the provided text.
• Outcome or Current Status: Not Instituted - Procedural

4. US case filed in U.S. Supreme Court

• Plaintiff(s): Not explicitly stated in the provided text.
• Defendant(s): Not explicitly stated in the provided text.
• Jurisdiction: U.S. Supreme Court
• Case Number: 21-118
• Filing Date: Not explicitly stated in the provided text.
• Outcome or Current Status: Litigation (status not further detailed)

5. First worldwide family litigation filed

• Plaintiff(s): Not explicitly stated in the provided text.
• Defendant(s): Not explicitly stated in the provided text.
• Jurisdiction: Not explicitly stated in the provided text (indicated as "First worldwide family litigation")
• Case Number: Not explicitly stated in the provided text.
• Filing Date: Not explicitly stated in the provided text.
• Outcome or Current Status: Litigation (status not further detailed)

6. US case filed in Court of Appeals for the Federal Circuit

• Plaintiff(s): Not explicitly stated in the provided text.
• Defendant(s): Not explicitly stated in the provided text.
• Jurisdiction: Court of Appeals for the Federal Circuit
• Case Number: 22-1904
• Filing Date: Not explicitly stated in the provided text.
• Outcome or Current Status: Litigation (status not further detailed)

7. US case filed in Court of Appeals for the Federal Circuit

• Plaintiff(s): Not explicitly stated in the provided text.
• Defendant(s): Not explicitly stated in the provided text.
• Jurisdiction: Court of Appeals for the Federal Circuit
• Case Number: 21-1043
• Filing Date: Not explicitly stated in the provided text.
• Outcome or Current Status: Litigation (status not further detailed)

8. US case filed in Court of Appeals for the Federal Circuit

• Plaintiff(s): Not explicitly stated in the provided text.
• Defendant(s): Not explicitly stated in the provided text.
• Jurisdiction: Court of Appeals for the Federal Circuit
• Case Number: 21-1046
• Filing Date: Not explicitly stated in the provided text.
• Outcome or Current Status: Litigation (status not further detailed)

Proceedings overview

There is one known AIA trial proceeding on file for US Patent 9001774, IPR2020-00642, which was filed by Unified Patents. This proceeding was not instituted due to procedural reasons, meaning the PTAB did not reach a decision on the merits of the patentability claims. As such, all claims of US9001774 remain untested by the PTAB, offering no direct defensive hardening or invalidation for a defendant.

IPR2020-00642 — Unified Patents v. Unwired Planet International Ltd

• Type: Inter Partes Review
• Filed: Not explicitly stated in the provided patent text or search results, but the case number IPR2020-00642 indicates a filing in the year 2020.
• Status: Not Instituted - Procedural. This means the petition for IPR was terminated before the PTAB made a decision on whether to institute a full trial on the merits.
• Judge panel: A judge panel was not publicly identified for this proceeding, as it was not instituted.
• Petition grounds: The specific claims challenged and prior art grounds are not detailed in the provided Google Patents data or the general search results. Given that the petitioner is Unified Patents, it is highly probable the petition asserted unpatentability under 35 U.S.C. §§ 102 and/or 103 based on prior art references.
• Institution decision: Denied (procedural). The proceeding was "Not Instituted - Procedural". The specific reasoning for this procedural denial is not detailed in the provided information, but such denials often occur due to factors like parallel litigation (Fintiv factors), settlement between parties, or other administrative reasons that prevent the Board from reaching the merits of institution.
• Final Written Decision (if issued): No Final Written Decision was issued as the proceeding was not instituted.
• Settlement / termination: The proceeding was procedurally terminated. This often indicates a settlement between the petitioner and patent owner, or a joint request for termination before an institution decision or final decision. The specific terms of any settlement are usually confidential.
• Appeal: No appeal to the Federal Circuit occurred as no Final Written Decision was rendered.
• Defensive value: Since this IPR was procedurally terminated before an institution decision on the merits, it offers no direct ruling on the patentability of the claims of US9001774. Therefore, it does not currently impact the patent's validity or provide specific claims that are invalidated. A defendant facing assertion might investigate the specific grounds raised in Unified Patents' petition, if publicly accessible, to inform their own invalidity contentions.

Strategic summary

Currently, all claims of US9001774 remain UNTESTED by the PTAB. The single IPR filed, IPR2020-00642 by Unified Patents, was terminated procedurally and did not result in an institution decision on the merits. This means that the PTAB has not made any determination regarding the patentability of any claim in this patent.

The estoppel landscape for US9001774 is therefore largely open. Since no Final Written Decision was issued, the statutory estoppel provisions of 35 U.S.C. § 315(e)(2) do not apply to Unified Patents (or their privies) for the grounds that were raised or reasonably could have been raised. This implies that potential petitioners or defendants are not barred from asserting prior art grounds against this patent in district court litigation or a new PTAB proceeding (subject to other PTAB rules like serial petitioning).

The involvement of Unified Patents as a petitioner is a common "pattern signal" for NPE cases. Unified Patents typically files IPRs against patents being asserted by NPEs to clear the landscape for its members. The fact that this IPR was procedurally terminated without a merits decision suggests that a resolution was reached between the parties, likely a settlement.

Recommended next steps

• Given that the patent US9001774 expired on March 27, 2026, the utility of filing a new IPR is significantly diminished, as the patent can no longer be asserted for new infringements.
• For any defendant facing assertions related to past infringement of US9001774, it is advisable to review the petition for IPR2020-00642 by Unified Patents (if publicly available via PTAB E2E search or through a direct request if allowed) to understand the specific prior art and arguments Unified Patents presented. These grounds, having not been adjudicated on the merits, could potentially be used in a district court defense.
• The absence of PTAB activity resulting in a final written decision means that the patent owner, Unwired Planet International Ltd., has not had any claims definitively confirmed or invalidated by the PTAB. This means any infringement arguments are based on claims whose validity has not been tested in this forum.

Inventors

• Farooq Khan: Employer at the time of filing is not explicitly stated in the provided patent text. The original assignee was [[Samsung Electronics Co Ltd](/litigations/by-plaintiff/Samsung%20Electronics%20Co%20Ltd).](/litigations/by-plaintiff/Samsung%20Electronics%20Co%20Ltd.)

Original assignee

The original assignee was Samsung Electronics Co Ltd. It is widely known that Samsung Electronics Co Ltd ships a vast array of products embodying wireless communication technologies, which would include technologies related to channel estimation in OFDM networks. Samsung is a global operating company with diverse business lines including electronics, mobile communications, and home appliances. Samsung Electronics Co Ltd is currently operating.

Assignment timeline

The Google Patents record itself lists the following reassignments:

• 2017-09-07 (executed) / recorded 2017-09-07 - Reel 043525/0719
  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: KHAN, FAROOQ (Inventor)
  • Assignee: SAMSUNG ELECTRONICS CO., LTD.
  • Correspondent: Not specified in Google Patents, requires USPTO Assignment Search for full detail.
  • Context: Internal transfer / formalization of inventor's interest to original assignee.
• 2017-09-08 (executed) / recorded 2017-09-08 - Reel 043537/0837
  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: SAMSUNG ELECTRONICS CO., LTD.
  • Assignee: UNWIRED PLANET INTERNATIONAL LIMITED
  • Correspondent: Not specified in Google Patents, requires USPTO Assignment Search for full detail.
  • Context: Transfer-to-asserter.
• 2017-09-09 (executed) / recorded 2017-09-09 - Reel 043539/0864
  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: SAMSUNG ELECTRONICS CO., LTD.
  • Assignee: UNWIRED PLANET INTERNATIONAL LIMITED
  • Correspondent: Not specified in Google Patents, requires USPTO Assignment Search for full detail.
  • Context: Confirmatory assignment or related transfer to asserter.

To fully reconstruct the assignment record and identify correspondents, a direct search of the USPTO Assignment Center is necessary. However, since the current time is 2026-05-29, and the patent expired on 2026-03-27, obtaining real-time USPTO Assignment Center data may not be feasible through automated search. Based on the provided prompt and the Google Patents data, the provided reassignments will be used.

Timeline diagram

timeline
    title Ownership of US 9001774
    2013 : Filed by Samsung Electronics
    2015 : Issued to Samsung
    2017 : Inventor assigned to Samsung
         : Samsung assigned to Unwired Planet
         : Samsung assigned to Unwired Planet
    2026 : Patent Expired

NPE / troll-pattern signals

1. Shell-entity transfer — present.

   • 2017-09-08 (executed) / recorded 2017-09-08 — Reel 043537/0837
     • Assignee: UNWIRED PLANET INTERNATIONAL LIMITED. Unwired Planet is a known NPE.
   • 2017-09-09 (executed) / recorded 2017-09-09 — Reel 043539/0864
     • Assignee: UNWIRED PLANET INTERNATIONAL LIMITED.

2. Known asserter in the chain — present.

   • 2017-09-08 (executed) / recorded 2017-09-08 — Reel 043537/0837
     • Assignee: UNWIRED PLANET INTERNATIONAL LIMITED. Unwired Planet is widely recognized as a patent assertion entity.
   • 2017-09-09 (executed) / recorded 2017-09-09 — Reel 043539/0864
     • Assignee: UNWIRED PLANET INTERNATIONAL LIMITED.

3. Repeat correspondent across the chain — unclear. The provided Google Patents data does not include correspondent information. A direct USPTO Assignment Center search would be required to determine this.

4. Cascading transfers — not present. There are two assignments to Unwired Planet on consecutive days (September 8 and September 9, 2017), but these appear to be related transfers from the same assignor (Samsung) to the same assignee (Unwired Planet), likely formalizing the same transaction, rather than a chain of transfers through different entities.

5. Pre-litigation transfer — unclear. While the transfer to Unwired Planet occurred in September 2017, the earliest litigation mentioned in the Google Patents record is 2019-cv-00066 filed in Texas Eastern District Court. Without explicit filing dates for all litigation events, it's unclear if the transfer occurred within 6 months of the first assertion of this specific patent family.

6. Bankruptcy fire-sale — not present. Samsung Electronics Co Ltd is an operating company and no bankruptcy event is indicated for them or for Unwired Planet in relation to the patent acquisition.

7. Privateering — unclear. While the transfer is from an operating company (Samsung) to an NPE (Unwired Planet), the specific nature of any agreement between them (e.g., whether Samsung retains an interest in assertion proceeds or directs the litigation) is not discernible from the provided patent text.

8. Defensive aggregator (anti-NPE) — not present. The chain ends with Unwired Planet International Ltd., a known patent asserter, not a defensive aggregator.

Verdict

NPE — high confidence. The patent was assigned from an operating company (Samsung Electronics Co Ltd) to Unwired Planet International Limited, which is a widely recognized patent assertion entity. This transfer to a known NPE is a strong signal. The recurring assignment to Unwired Planet in September 2017 (Reel 043537/0837 and Reel 043539/0864) further solidifies this conclusion.

For verification, see the USPTO Assignment Center search page (https://assignmentcenter.uspto.gov/) and search for patent number US9001774.

As a technical patent analyst, I have analyzed US Patent 9,001,774B2 (hereafter '774 patent) and its cited prior art references. The priority date for the '774 patent is April 21, 2005.

The '774 patent describes a system and method for channel estimation in a delay diversity wireless communication system, particularly in OFDM/OFDMA networks. Key aspects include:

• Receiving uplink signals to determine processing parameters (time delay, phase rotation, gain) for downlink transmissions from multiple antenna ports (Claim 1, 6).
• Processing data symbols based on these parameters (Claim 1).
• Transmitting pilots, which may or may not be processed by these parameters (Claim 2, 7).
• Demodulating data symbols using the processing parameters and pilots, which may involve channel estimation (Claim 6, 10).
• Determination of parameters on a user-by-user basis (Claim 3, 8).
• Time delay in time domain, phase rotation in frequency domain (Claim 4, 9).

Below is an analysis of the most relevant prior art cited within the '774 patent, focusing on those published before the '774 patent's priority date of April 21, 2005. The brief descriptions are primarily based on the titles and general context provided in the '774 patent, as full texts of the cited patents were not provided for a deeper analysis. Potential anticipation under 35 U.S.C. § 102 is indicated where conceptual overlap is apparent.

Relevant Prior Art Analysis

1. EP0807989A1

• Full Citation: EP0807989A1, "Devices for transmitter path weights and methods therefor," Motorola Ltd.
• Publication Date: November 19, 1997 (Pre-dates '774 priority date)
• Brief Description: The patent generally describes devices and methods for weighting transmitter paths. While the details of the weighting are not specified in the '774 patent's provided text, "path weights" could imply gain adjustments.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1, 6: The concept of applying "gain" as a processing parameter (Claim 1) or receiving a processing parameter including gain (Claim 6) could potentially be anticipated, depending on the specifics of how "path weights" are determined and applied.

2. US6219334B1

• Full Citation: US6219334B1, "Receiving apparatus for receiving orthogonal frequency division multiplexing signal and receiving method thereof," Kabushiki Kaisha Toshiba.
• Publication Date: April 17, 2001 (Pre-dates '774 priority date)
• Brief Description: This patent pertains to a receiving apparatus and method for OFDM signals, suggesting a focus on receiver-side processing for OFDM communication.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 6, 10: The general concept of receiving and demodulating OFDM data, particularly with channel estimation for an OFDM system, could be broadly anticipated by a receiving apparatus for OFDM signals. However, the specific "processing parameter" aspect of the '774 patent's claims would require detailed comparison.

3. EP1185048A2

• Full Citation: EP1185048A2, "Preamble design for multicarrier transmission over channels with multiple inputs and outputs," Nortel Networks Limited.
• Publication Date: March 6, 2002 (Pre-dates '774 priority date)
• Brief Description: This patent addresses the design of preambles for multicarrier (e.g., OFDM) transmission in MIMO systems. Preambles are often used for channel estimation and synchronization.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1, 5: If the preamble design implicitly allows for determination of channel characteristics that could lead to processing parameters like delays or gains, or if the uplink signal in claim 5 (which includes preamble) is used for similar purposes.
  • Claim 6: The reception of pilots (which can be part of preambles) for channel estimation.

4. EP1185001A2

• Full Citation: EP1185001A2, "Adaptive time diversity and spatial diversity for OFDM," Nortel Networks Limited.
• Publication Date: March 6, 2002 (Pre-dates '774 priority date)
• Brief Description: This patent covers adaptive time and spatial diversity techniques for OFDM. Spatial diversity typically involves multiple transmit antennas, and time diversity can involve delays. This strongly aligns with the core concept of "delay diversity" in the '774 patent.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1, 2, 3, 4, 6, 7, 8, 9: The broad concepts of using time delays and spatial diversity (multiple antennas) in an OFDM system to achieve diversity. If "adaptive" implies selection based on channel conditions, it could potentially anticipate the "determining a processing parameter" (Claim 1) and "user-by-user basis" (Claim 3) aspects, as well as the use of delays and phase rotations (Claim 4). The '774 patent specifically mentions "delayed diversity wireless network was disclosed previously U.S. patent application Ser. No. 11/327,799," which itself mentions "multiple copies of the same OFDM symbol are delayed by different delay values." The EP1185001A2's title directly mentions "time diversity," strongly suggesting delay use.

5. EP1359684A1

• Full Citation: EP1359684A1, "Wireless transmission using an adaptive transmit antenna array," Motorola Energy Systems Inc.
• Publication Date: November 5, 2003 (Pre-dates '774 priority date)
• Brief Description: This patent relates to wireless transmission using adaptive transmit antenna arrays. Adaptive arrays often adjust transmission characteristics (like gains, phases) based on channel conditions.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1, 3, 4, 6, 8, 9: Similar to EP1185001A2, "adaptive" implies channel-dependent adjustments. The use of "transmit antenna array" directly relates to using multiple antenna ports. If "adaptive" includes adjusting gains and delays/phase rotations, it could potentially anticipate many aspects of parameter determination and application.

6. US20040086055A1

• Full Citation: US20040086055A1, "Pilot-aided channel estimation for OFDM in wireless systems," Ye Li.
• Publication Date: May 6, 2004 (Pre-dates '774 priority date)
• Brief Description: This publication focuses on channel estimation techniques using pilot signals specifically for OFDM wireless systems.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1, 6, 10: The fundamental concept of using pilot signals for channel estimation in OFDM, which is a key part of the '774 patent's methods. The determination of "processing parameters based on the received uplink signal" (Claim 1) or "demodulating ... based on the processing parameter, the first pilot and the second pilot" (Claim 6) with "estimating a channel using the first pilot, the second pilot" (Claim 10) are directly addressed.

7. US20040110510A1

• Full Citation: US20040110510A1, "Apparatus and method for channel quality estimation and link adaptation in orthogonal frequency division multiplexing (OFDM) wireless communication system," Taehyun Jeon.
• Publication Date: June 10, 2004 (Pre-dates '774 priority date)
• Brief Description: This patent application describes methods and apparatus for channel quality estimation and link adaptation in OFDM systems. Channel quality estimation often informs transmission parameters.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1, 6, 10: The concept of estimating channel quality (which is a form of channel estimation) and using it for link adaptation could broadly encompass determining processing parameters (like gains/delays for better link) and using channel estimates for demodulation.

8. US20040131011A1

• Full Citation: US20040131011A1, "Transmission signals, method and apparatus," Kabushiki Kaisha Toshiba.
• Publication Date: July 8, 2004 (Pre-dates '774 priority date)
• Brief Description: This reference generally discusses transmission signals, methods, and apparatus, but without further detail, it's hard to assess specific overlap.
• Potential Anticipation (35 U.S.C. § 102): A detailed analysis would require the full text. Based solely on the title, broad aspects of "transmitting a first pilot and a second pilot; and transmitting a first data symbol and a second data symbol on two antenna ports" (Claim 1) or "receiving a first pilot, a second pilot, a first data symbol and a second data symbol transmitted on the two antenna ports" (Claim 6) could be related.

9. US20040156328A1

• Full Citation: US20040156328A1, "Random access for wireless multiple-access communication systems," Walton J. Rodney.
• Publication Date: August 12, 2004 (Pre-dates '774 priority date)
• Brief Description: This patent application focuses on random access procedures in wireless multiple-access communication systems.
• Potential Anticipation (35 U.S.C. § 102): Less direct relevance to channel estimation and delay diversity processing, but uplink signals (Claim 1, 5, 6) could be related to random access. Unlikely to anticipate the core aspects of parameter determination and application.

10. EP1453223A1

• Full Citation: EP1453223A1, "Transmission diversity communication device," Fujitsu Limited.
• Publication Date: September 1, 2004 (Pre-dates '774 priority date)
• Brief Description: This patent describes a "transmission diversity communication device," which directly relates to the diversity aspects of the '774 patent, likely involving multiple antennas.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1, 6: The fundamental concept of transmit diversity using multiple antenna ports for data transmission. The specific nature of the "processing parameters" (delays, gains, phase rotations) would require more detailed comparison with the EP patent.

11. US20040248527A1

• Full Citation: US20040248527A1, "Device and method for compensating for phase distortion in base station of OFDMA-based cellular system," Youn-Ok Park.
• Publication Date: December 9, 2004 (Pre-dates '774 priority date)
• Brief Description: This patent application focuses on compensating for phase distortion in OFDMA base stations. "Phase rotation" is explicitly mentioned as a processing parameter in the '774 patent (Claims 1, 6).
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1, 4, 6, 9: The use of "phase rotation" as a processing parameter, especially if determined based on channel characteristics. This seems highly relevant to claims 4 and 9 of the '774 patent.

12. US6842487B1

• Full Citation: US6842487B1, "Cyclic delay diversity for mitigating intersymbol interference in OFDM systems," Telefonaktiebolaget Lm Ericsson (Publ).
• Publication Date: January 11, 2005 (Pre-dates '774 priority date)
• Brief Description: This patent explicitly teaches "cyclic delay diversity for mitigating intersymbol interference in OFDM systems." This is highly relevant as the '774 patent states, "In an advantageous embodiment, the delays introduced by OFDM symbol processing block 230 are cyclic delays, as disclosed in U.S. patent application Ser. No. 11/327,799."
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1, 4, 6, 9: The core concept of introducing time delays (specifically cyclic delays) for diversity in OFDM systems using multiple antennas (implied by diversity). This directly addresses the "time delay" and potentially "phase rotation" aspects (as time delay translates to phase rotation in frequency domain per the '774 patent).

13. US20050163263A1

• Full Citation: US20050163263A1, "Systems and methods for frequency acquisition in a wireless communication network," Gupta Alok K.
• Publication Date: July 28, 2005 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: This patent relates to frequency acquisition.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

14. US20050176436A1

• Full Citation: US20050176436A1, "Channel estimation for a wireless communication system with multiple parallel data streams," Ashok Mantravadi.
• Publication Date: August 11, 2005 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: This patent describes channel estimation in systems with multiple parallel data streams, common in MIMO.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

15. US20050201268A1

• Full Citation: US20050201268A1, "OFDM signal transmission method and apparatus," Tsuguhide Aoki.
• Publication Date: September 15, 2005 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: This relates to OFDM signal transmission methods and apparatus.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

16. US20050265477A1

• Full Citation: US20050265477A1, "Wireless transmission method and wireless transmitter having a plurality of antennas," Kabushiki Kaisha Toshiba.
• Publication Date: December 1, 2005 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: This describes a wireless transmission method and transmitter with multiple antennas.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

17. US6982670B2

• Full Citation: US6982670B2, "Phase management for beam-forming applications," Farrokh Mohamadi.
• Publication Date: January 3, 2006 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: This patent discusses phase management in beamforming.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

18. US20060034163A1

• Full Citation: US20060034163A1, "Pilot transmission schemes for a multi-antenna system," Gore Dhananjay A.
• Publication Date: February 16, 2006 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: This describes pilot transmission schemes for multi-antenna systems.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

19. US7003415B2

• Full Citation: US7003415B2, "Delay profile estimation apparatus and a correlating unit," Fujitsu Limited.
• Publication Date: February 21, 2006 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: This patent relates to delay profile estimation, which is relevant for understanding multipath channels.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

20. US20060045200A1

• Full Citation: US20060045200A1, "Signal receiving method in MIMO system and device therefor," Wladimir Bocquet.
• Publication Date: March 2, 2006 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: This describes a signal receiving method in MIMO systems.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

21. US7082159B2

• Full Citation: US7082159B2, "Methods and arrangements in a telecommunications system," Telefonaktiebolaget Lm Ericsson (Publ).
• Publication Date: July 25, 2006 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: General methods and arrangements in telecommunication systems.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

22. US7206554B1

• Full Citation: US7206554B1, "Transmit diversity with formed beams in a wireless communications system using a common pilot channel," Arraycomm Llc.
• Publication Date: April 17, 2007 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: This patent relates to transmit diversity with formed beams using a common pilot channel.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

23. US7251291B1

• Full Citation: US7251291B1, "System and method for I/Q imbalance compensation," Nortel Networks Limited.
• Publication Date: July 31, 2007 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: This patent addresses I/Q imbalance compensation.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

24. US20070281624A1

• Full Citation: US20070281624A1, "Method and apparatus for channel feedback," Motorola, Inc.
• Publication Date: December 6, 2007 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: This describes methods and apparatus for channel feedback, which could relate to transmitting processing parameters back to the base station.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

25. US7428267B2

• Full Citation: US7428267B2, "Uplink channel estimation system for orthogonal frequency division multiple access system and method thereof," Electronics And Telecommunications Research Institute.
• Publication Date: September 23, 2008 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: This patent covers uplink channel estimation in OFDMA systems.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

26. US7453793B1

• Full Citation: US7453793B1, "Channel estimation for OFDM communication systems including IEEE 802.11A and extended rate systems," Qualcomm Incorporated.
• Publication Date: November 18, 2008 (Post-dates '774 priority date, not prior art for 102(a))
• Brief Description: This patent addresses channel estimation for OFDM communication systems, including IEEE 802.11A.
• Prior Art Status: Not prior art under 35 U.S.C. § 102 for the '774 patent's priority date.

Most Relevant Prior Art Summary

Based on the titles and their direct relevance to the claims of US9001774B2 and its disclosed "delay diversity" and "channel estimation" concepts, the following references appear to be most relevant for potential anticipation under 35 U.S.C. § 102:

• EP1185001A2 ("Adaptive time diversity and spatial diversity for OFDM"): Directly addresses "time diversity" and "spatial diversity" in OFDM, which are foundational to the '774 patent's delay diversity approach.
• US6842487B1 ("Cyclic delay diversity for mitigating intersymbol interference in OFDM systems"): Explicitly mentions "cyclic delay diversity" in OFDM, a specific implementation detailed in the '774 patent. This is highly relevant to claims involving time delays and phase rotations.
• US20040086055A1 ("Pilot-aided channel estimation for OFDM in wireless systems"): Directly focuses on using pilots for channel estimation in OFDM, a central theme of the '774 patent's claims for both determining processing parameters and demodulation.
• EP1359684A1 ("Wireless transmission using an adaptive transmit antenna array"): Discusses adaptive transmission from antenna arrays, potentially covering the determination and application of gains and phase/delay adjustments from multiple antennas.
• US20040248527A1 ("Device and method for compensating for phase distortion in base station of OFDMA-based cellular system"): Addresses phase distortion compensation, which aligns with the "phase rotation" processing parameter in the '774 patent.

These references collectively touch upon multiple antennas, diversity through delays, adaptive transmission, and pilot-aided channel estimation in OFDM/OFDMA systems, which are key elements of the '774 patent's claims. A definitive determination of anticipation would require a full review of the specifications and claims of each cited patent.

Under 35 U.S.C. § 103, an invention is considered obvious if the differences between the claimed invention and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art (PHOSITA). For an obviousness rejection, there must be a motivation to combine the prior art references, and a reasonable expectation of success.

Based on the "BACKGROUND OF THE INVENTION" section of US patent 9001774, the following prior art and problem statement are identified:

Identified Prior Art:

1. U.S. patent application Ser. No. 11/327,799, filed on Jan. 6, 2006 (referred to hereafter as P1). This reference is explicitly incorporated by reference into US9001774. P1 discloses a technique for artificially introducing frequency diversity into an Orthogonal Frequency Division Multiplexing (OFDM) environment. Specifically, in the device disclosed in P1, "multiple copies of the same OFDM symbol are delayed by different delay values, then amplified by the same or different gain values, and then transmitted from different antennas." This process "artificially introduces frequency-selective fading in the OFDM channel, thereby allowing frequency selectivity to be exploited".

Problem Identified by US9001774 (as stated in its background):

The US9001774 patent identifies a need to improve upon the technique of P1. It states: "However, when selecting the symbol processing parameters (i.e., delay values and the gain values) applied to the OFDM symbols, it is important to take into consideration the user channel type and the mobile speed. To accomplish this, channel estimation is performed and the symbol processing parameters are determined based on the channel estimates and mobile speed. Therefore, there is a need for improved apparatuses and methods for performing channel estimation in an OFDM wireless network that artificially introduces frequency diversity by delaying and amplifying multiple copies of the same OFDM symbol and then transmitting the delayed and amplified OFDM symbols from different transmit antennas."

Analysis of Obviousness:

The claims of US9001774 address the problem stated in its background. For example, Claim 1 and Claim 6 are representative:

• Claim 1 of US9001774: "A method, comprising: receiving an uplink signal; determining a processing parameter for transmission of data on two antenna ports, the processing parameter including at least one of a time delay, a phase rotation and a gain based on the received uplink signal; transmitting a first pilot and a second pilot; and transmitting a first data symbol and a second data symbol on two antenna ports, at least one of the first data symbol and the second data symbol being processed based on the processing parameter."

• Claim 6 of US9001774: "A method, comprising: receiving a processing parameter for transmission of data on two antenna ports, the processing parameter including at least one of a time delay, a phase rotation and a gain determined based on a received uplink signal; receiving a first pilot, a second pilot, a first data symbol and a second data symbol transmitted on the two antenna ports; and demodulating the first data symbol and the second data symbol based on the processing parameter, the first pilot and the second pilot."

Combinations of Prior Art References and Motivation for Combination:

A PHOSITA would have been motivated to combine U.S. patent application Ser. No. 11/327,799 (P1) with the general knowledge in the art regarding channel estimation and adaptive transmission in wireless communication systems.

1. Teachings of P1: P1 clearly teaches the core concept of transmitting data symbols from multiple antennas with applied delays and gains to achieve artificial frequency diversity. This directly addresses the elements of transmitting processed data symbols with delays and gains from two antenna ports, as recited in Claims 1 and 6.

2. General Knowledge in the Art (Channel Estimation and Adaptive Transmission): At the priority date of US9001774 (April 21, 2005), it was a well-established practice in wireless communication systems, especially OFDM/OFDMA networks, to:

   • Transmit pilot signals (also known as training sequences or reference signals) from base stations to allow subscriber stations to estimate the wireless channel characteristics. The US9001774 patent itself lists "pilot" as a prior art keyword.
   • Perform channel estimation based on received signals (including pilot signals or uplink signals).
   • Use channel estimates to adapt various transmission parameters (e.g., modulation, coding rate, power, spatial processing parameters) to optimize system performance (e.g., throughput, reliability, spectral efficiency). This concept is broadly known as adaptive transmission or link adaptation.
   • Utilize feedback mechanisms, where a subscriber station estimates channel conditions and reports channel state information (CSI) or recommended transmission parameters back to the base station via an uplink signal. Alternatively, in TDD systems, channel reciprocity could be used, where the base station estimates the downlink channel from an uplink signal.

3. Motivation for Combination: The motivation for combining these elements is explicitly stated in the "BACKGROUND OF THE INVENTION" section of US9001774 itself. The patent identifies the problem that P1's delay diversity scheme, while introducing artificial frequency diversity, lacks a mechanism for optimally selecting the "delay values and the gain values" based on dynamic channel conditions, such as "user channel type and the mobile speed". The patent then explicitly states that "To accomplish this, channel estimation is performed and the symbol processing parameters are determined based on the channel estimates and mobile speed."

Therefore, a PHOSITA, aware of P1's delay diversity technique and the inherent challenge of optimizing its parameters, would have been directly motivated to apply conventional channel estimation and adaptive transmission principles. It would have been obvious to:

• Use standard pilot signals (transmitted as in Claim 1 or received as in Claim 6) to perform channel estimation.
• Determine the "processing parameter" (gains and delays, as described in P1, or their frequency-domain equivalent, phase rotation, as acknowledged in the patent's detailed description) based on these channel estimates.
• Either feed these determined parameters back to the base station via an uplink signal (as inferred from Claim 1, "receiving an uplink signal") or have the base station determine them from an uplink signal, for use in processing downlink data transmissions.
• Demodulate data symbols at the receiver using the knowledge of these parameters and the pilot signals (as in Claim 6).

The combination would yield a predictable improvement by making the delay diversity scheme adaptive and more efficient under varying channel conditions, directly addressing the "need" identified by the patent itself. The inclusion of "phase rotation" as a parameter would also be obvious, as the patent explains that a time delay in the time domain translates to a phase rotation in the frequency domain, a fundamental concept in OFDM systems.