Obviousness

Obviousness Analysis under 35 U.S.C. § 103

This analysis will assess the obviousness of US Patent 9253428 by identifying combinations of the explicitly cited prior art references (ETSI standard EN 302 755 V1.3.1 for DVB-T2 and 3GPP TS 36.211 V9.1.0 for LTE E-UTRA modulation) and explaining the motivation a Person Having Ordinary Skill in the Art (PHOSITA) would have had to combine them.

A PHOSITA is presumed to have ordinary creativity and to be aware of all pertinent prior art. The key question for obviousness is whether the claimed invention, as a whole, would have been obvious to a PHOSITA at the time of the invention (i.e., before the priority date of May 21, 2014) in light of the prior art.

Prior Art Summary

1. ETSI Standard EN 302 755 V1.3.1 (DVB-T2 Standard, published April 2012): This standard describes the frame structure, channel coding, and modulation for a second-generation digital terrestrial television broadcasting system. It utilizes COFDM, T2 frames, super frames, P1 and L1 signaling, Physical Layer Pipes (PLPs), BCH and LDPC coding, QAM symbol constellations, and various interleaving techniques. It also includes methods for Peak-to-Average-Power-Ratio (PAPR) reduction. The patent explicitly states that its DTV transmitter apparatus is "essentially the same" as specified in this standard.
2. 3GPP TS 36.211 V9.1.0 Standard (LTE E-UTRA Modulation, published March 2010): This standard defines the Evolved Universal Terrestrial Radio Access (E-UTRA) modulation used in LTE cellular telephony for downlink signals. It specifies using COFDM carriers to convey signaling information, including Master Information Blocks (MIBs), synchronization signals (Primary Synchronization Signal (PSS) based on Zadoff-Chu sequences, and Secondary Synchronization Signal (SSS) based on scrambled pseudo-random sequences), and pilot carriers for various purposes. A key feature is its bandwidth-agnostic nature, where information about RF channel bandwidth is conveyed within the MIB.

Obviousness Combinations and Motivations

The core inventive step claimed by US9253428 is the integration of LTE-like metadata signaling into a DVB-T2-based DTV broadcasting system, specifically using dedicated mid-band COFDM carriers to convey this metadata, including signature sequences for signaling new broadcast services.

Combination 1: DVB-T2 Standard + LTE E-UTRA Standard

Claims potentially rendered obvious: Independent Claims 1, 13, and 14, and dependent claims relying on these features.

Reasoning:

1. Known Components: The DVB-T2 standard provides a complete framework for terrestrial digital television broadcasting using COFDM, including details on frame structure, modulation (QAM), coding (BCH-LDPC), and the use of various carriers for different types of information (e.g., L1 signaling, pilot carriers). The LTE E-UTRA standard, also using COFDM, provides a robust and bandwidth-agnostic mechanism for transmitting essential system information (metadata) via dedicated carriers in the central portion of a frequency band. This includes the specific use of Zadoff-Chu sequences for primary synchronization and scrambled pseudo-random sequences for secondary synchronization, along with MIBs to convey critical operational parameters like bandwidth.
2. Motivation to Combine: A PHOSITA in the field of digital television broadcasting, seeking to enhance DVB-T2 systems, would have several motivations to combine elements from the LTE E-UTRA standard:
   • Bandwidth Agnosticism: The patent explicitly discusses the desire for a "bandwidth-agnostic way to specify the nature of RF channels selected for reception" to allow portable DTV receivers to work across countries with different RF bandwidths (e.g., 6 MHz in North America, 8 MHz in Europe/Asia). The LTE E-UTRA standard directly addresses this need by conveying RF channel bandwidth information within MIBs using its central carriers, making it inherently bandwidth-agnostic. A PHOSITA would be motivated to adopt this known solution from a related COFDM communication system to solve the identified problem in DTV.
   • Robust Metadata Signaling: The patent also notes that "in-band signaling undesirably complicates time-division multiplexing... More important, in-band signaling undesirably complicates de-multiplexing of components of the baseband signal in a COFDM DTV receiver. In-band signaling tends to reduce digital payload". DVB-T2 already uses L1 signaling, but the patent notes that "additional signaling capability may be required, and per custom this has been afforded by so-called 'in-band' signaling wherein control signals replace portions of the broadcast normally allocated to DTV signal." The LTE E-UTRA system's dedicated, robust central carriers for MIBs and synchronization signals provide an alternative, more efficient, and less intrusive method for transmitting critical metadata, avoiding the drawbacks of in-band signaling. A PHOSITA would naturally look to other COFDM-based digital communication systems for solutions to metadata transmission challenges.
   • Signaling New Broadcast Services/Standards: The patent highlights the need for DTV receivers to be signaled about "the general type of DTV broadcasting system or other broadcasting system currently occupied an RF channel" to facilitate receivers determining if they can usefully receive the signal, especially for "universal" standards like ATSC 3.0. The use of unique "signature sequences" (Zadoff-Chu and scrambled PN sequences) in LTE for primary and secondary synchronization, which can inherently convey different types of system information, would provide a clear motivation for a PHOSITA to adapt this robust signaling mechanism for identifying different DTV broadcast standards or new services within the DVB-T2 framework.
   • Efficiency: The patent acknowledges the desire that "as many as possible of the COFDM carriers be dedicated to conveying DTV signals, rather than metadata descriptive of the DTV signals." By dedicating a smaller, central set of carriers for metadata (as in LTE), while the bulk of the spectrum carries DTV content (as in DVB-T2), a PHOSITA would achieve a more efficient spectral allocation for DTV data.
3. Predictable Results: Combining the DVB-T2 system for primary content transmission with the LTE E-UTRA method for robust, bandwidth-agnostic metadata signaling would yield predictable results: a DTV system with improved metadata handling, better interoperability across different RF bandwidths, and a clear mechanism for signaling new broadcast standards without significantly impacting the main DTV data payload. The modifications mentioned in the patent, such as adjusting the number of carriers for metadata (from 72 in LTE to 64 for DTV) and extending sub-frames, would be considered routine engineering choices for a PHOSITA adapting one known system to another.

Specific elements of the claims rendered obvious:

• Claim 1:
  • "broadcasting system for digital television (DTV) signals using coded orthogonal frequency-division multiplexed (COFDM) carrier waves." (Present in DVB-T2).
  • "a DTV signal generator modulating a first set of said COFDM carriers with said DTV signals, said first set of said COFDM carriers being located in frequency bands both below and above a central portion of a radio-frequency (RF) channel." (Present in DVB-T2, as it occupies a frequency band).
  • "a metadata generator modulating a second set of said COFDM carriers with metadata including synchronization signals and transmission-mode signals, said second set of said COFDM carriers being located in said central portion of said RF channel and being distinct from said first set of said COFDM carriers." (Motivated by LTE E-UTRA's use of central carriers for MIBs and synchronization in a bandwidth-agnostic way, applied to DTV to avoid in-band signaling).
  • "said second set of said COFDM carriers signaling when a new broadcast service is used that differs from a previously-used broadcast service, said signaling being provided by modulating said second set of said COFDM carriers with respective elements of signature sequences, each of which signature sequences is composed of Zadoff-Chu sequences and repetitive pseudo-random sequences scrambled by a Zadoff-Chu sequence." (Directly adapting LTE's PSS (Zadoff-Chu) and SSS (scrambled PN31) for signaling system information to the context of indicating new broadcast services in DTV, driven by the need for DTV receivers to recognize different broadcast standards).
• Claim 13:
  • "DTV receiver apparatus for receiving COFDM DTV signals." (Present in DVB-T2 receivers).
  • "a front-end tuner converting said RF COFDM signals to digitized samples of baseband COFDM signals." (Standard receiver component).
  • "a Discrete Fourier Transform (DFT) computer demodulating said COFDM carriers from said digitized samples of said baseband COFDM signals to obtain said DTV signals and said metadata." (Standard COFDM receiver component).
  • "a QAM de-mapper de-mapping said demodulated central COFDM carriers to obtain baseband metadata signal therefrom." (De-mapping central carriers for metadata, motivated by the combined system).
  • "a controller receiving said baseband metadata signal from said QAM de-mapper, said controller responding to said baseband metadata signal to determine when a new broadcast service is used that differs from a previously-used broadcast service, said controller responding to said baseband metadata signal by detecting said signature sequences, each of which signature sequences is composed of Zadoff-Chu sequences and pseudo-random sequences scrambled by a Zadoff-Chu sequence." (Motivated by the need to interpret the LTE-like signaling in the DTV receiver, leveraging known LTE receiver components for synchronization signal detection).
• Claim 14: The method steps mirror the apparatus of Claim 1 and would be obvious for the same reasons as outlined above.

Secondary Considerations

While not explicitly discussed in the patent text, a full obviousness analysis would consider secondary considerations of non-obviousness, such as commercial success, long-felt but unsolved needs, failure of others, and unexpected results. Without this information, the analysis here is limited to the prior art and the motivation to combine.

Conclusion on Obviousness:

Given the explicit incorporation of the DVB-T2 standard for DTV broadcasting and the detailed description of adapting LTE E-UTRA modulation for metadata transmission, a PHOSITA would have been motivated to combine these two known technologies. The desire for bandwidth-agnostic signaling, robust metadata transmission, and the ability to signal new broadcast standards in DTV were recognized problems, and the LTE E-UTRA standard offered well-established solutions for these exact challenges within a COFDM framework. The adaptation of LTE's specific synchronization sequences (Zadoff-Chu and scrambled PN sequences) and MIB concept to the DVB-T2 environment for signaling new services would be considered an obvious design choice to achieve predictable improvements in DTV broadcasting. Therefore, the core claims of US9253428 appear to be obvious under 35 U.S.C. § 103 in light of a combination of the ETSI DVB-T2 standard and the 3GPP LTE E-UTRA standard.