Obviousness

The analysis below identifies combinations of prior art references that would render the claims of US Patent 10,917,272 obvious under 35 U.S.C. § 103, along with the motivation for a person having ordinary skill in the art (PHOSITA) to combine them.

The core of US Patent 10,917,272's independent claims (Claim 1 for transmission, Claim 11 for reception) revolves around a non-transitory computer-readable information storage medium that enables:

1. Two Packet Types: A first type with a header field using two distinct parts (different header bits) over two OFDM symbols, and a second type with a header field using four parts, where the first two parts repeat a first set of header bits and the last two parts repeat a second set of header bits.
2. Repetition with Different Order: For the second packet type, the repeated sets of header bits (e.g., the second OFDM symbol compared to the first, and the fourth OFDM symbol compared to the third) are transmitted or received in a different order.
3. Wireless OFDM Network Context: All within a wireless Orthogonal Frequency Division Multiplexing (OFDM) network.

Prior Art References for Obviousness Analysis

The patent itself discusses and cites several highly relevant prior art documents and technical discussions in its "Background" and "Summary" sections, which reveal the state of the art and the problems the inventors sought to solve:

1. ITU G.9960 ("ITU-T Recommendation G.9960: Next generation wire-line based home networking transceivers—Foundation," January 2009): This standard is explicitly mentioned as defining that "the header containing PHY H bits (header information block) is carried over one or two OFDM symbols (D=1 or 2), and within each symbol, multiple header information blocks are repeated over the entire frequency band." It also states that the "default value of D is 1, but expanding it to 2 in some cases is under discussion." Furthermore, G.9960 emphasizes that it is "essential to decode the header reliably".
2. "G.hn: PHY-Frame Header Extension" (ITU Temporary Document ITU-T SG-15/Q4 09CC-046, August 2009): This document, also cited in the patent's background, discusses the "possibility of carrying more than PHY H bits in the header (H=1 or 2)", implying the concept of an extended header (e.g., "Header Ext" as shown in FIG. 1 of the patent).
3. "G.hn: Using Two Symbols for the Header of PHY Frame on Coax" (ITU Temporary Document ITU-T 5G15/Q4 09XC-100, July 2009): This document, similar to 09CC-046, is noted for discussing the expansion of 'D' to 2.
4. Common General Knowledge in OFDM/Wireless Communications: It is a fundamental and well-known principle in wireless communication systems, especially those employing OFDM, that applying interleaving, scrambling, or reordering of data bits across redundant transmissions (e.g., in different time slots or different frequency subcarriers for repeated data) significantly enhances diversity gain and robustness against channel impairments such as frequency-selective fading and interference. This technique was widely understood and applied prior to the priority date of US10917272 (August 21, 2009).

Obviousness Combination and Rationale for Independent Claims 1 and 11

Combination: ITU G.9960 + "G.hn: PHY-Frame Header Extension" (09CC-046) + Common General Knowledge of Interleaving/Diversity.

Rationale for Combination:

A PHOSITA would have been motivated to combine these references to address the acknowledged challenges in reliable header decoding in OFDM networks, particularly in heterogeneous environments. The patent itself highlights the problem that "the level of frequency diversity is different depending on the bandplan, hence providing different header decodability if D is fixed to 1. If D is fixed to 2, then it increases reliability for the narrowband devices, but may also unnecessarily increase overhead for the wide-band devices." This problem statement, combined with the explicit discussions in the G.hn documents, would drive a PHOSITA to the claimed solution.

1. Variable Repetition of Header Information (Two vs. Four OFDM Symbols):

   • G.9960 explicitly teaches transmitting headers using one or two OFDM symbols (D=1 or 2). This establishes the concept of variable header repetition factors.
   • "G.hn: PHY-Frame Header Extension" introduces the concept of an extended header (H=1 or 2), meaning the header information itself can comprise multiple distinct parts (e.g., a "Header" and a "Header Ext" as depicted in FIG. 1 of US10917272).
   • Combining these, a PHOSITA would readily envision a scenario where an extended header (H=2, meaning two different parts) could be transmitted:
     • With D=1: Each of the two header parts occupies one OFDM symbol, totaling two OFDM symbols for the header. This directly corresponds to the "first packet type" of Claims 1 and 11, where the "first part comprising a first set of header bits... and a second part comprising a second set of header bits... different than the second set" are transmitted using a first and second OFDM symbol, respectively.
     • With D=2: Each of the two header parts is repeated twice over OFDM symbols. This would result in a total of four OFDM symbols dedicated to the header (e.g., first header part in symbol 1, same first header part in symbol 2; second header part in symbol 3, same second header part in symbol 4). This directly corresponds to the "second packet type" of Claims 1 and 11, where the first set of header bits is repeated (first and second parts of the second header field), and the third set of header bits is repeated (third and fourth parts of the second header field). The patent's own description of FIG. 1 states that "the second instance of a block with the same label is a copy of the prior block."

2. Repetition with Different Order for Diversity:

   • G.9960 emphasizes the "essential" need for reliable header decoding. The patent's background further notes the varying levels of "frequency diversity" across different bandplans affecting decodability.
   • Given the objective of enhancing reliability, and knowing that repetition (as taught by G.9960 for D=2) provides redundancy, a PHOSITA would consider how to maximize the benefit of this repetition. It is common general knowledge in wireless communication that simply repeating bits in the exact same order offers some redundancy but may not fully leverage channel diversity. Reordering or interleaving bits across repeated transmissions (e.g., the second OFDM symbol compared to the first, or the fourth compared to the third for the repeated header parts) is a standard and well-understood technique to achieve robust frequency diversity. This ensures that even if certain frequency subcarriers are affected by deep fades in one symbol, the reordered data in the subsequent, redundant symbol has a higher chance of being transmitted over different, more favorable subcarriers, thus increasing the probability of successful decoding.
   • Motivation: A PHOSITA, aiming to improve the "likelihood of correctly communicating header information" (as stated in dependent claims 2, 3, 8, 9, 12, 13, 18, 19), would be motivated to apply this known diversity-enhancing technique to the repeated header OFDM symbols described in G.9960 and its extensions. The phrase in the patent, "The modulation of the copied block may not be exactly the same as the original version", and the claim's "different order" are direct applications of this common general knowledge.

Obviousness of Dependent Claims

• Claims 2, 3, 8, 9, 12, 13, 18, 19 (Diversity for Reliability): These claims state that the transmission/reception of the same header bits in a different order provides diversity to increase the likelihood of correct communication. This is the inherent and well-understood benefit of interleaving/reordering for diversity, making these claims obvious once the "different order" aspect is considered obvious.
• Claims 4, 14 (SmartGrid Applications): The patent states, "The possibility of having narrower bandplans such as 25 MHz-PB and 12.5 MHz-PB are under discussion in order to support, for example, SmartGrid applications." Since the problem of diverse bandplans drove the need for variable header repetition, applying the solution to the identified use case of SmartGrid applications would be an obvious design choice for a PHOSITA.
• Claims 5, 15 (Support for Wireless Standards): The background already identifies IEEE 802.11, IEEE 802.16 (WiMAX), and ITU G.9960 as relevant standards for OFDM systems. Implementing the header repetition scheme within the context of supporting such known wireless standards is a straightforward and obvious application.
• Claims 6, 16 (MAP Frame Indicating D): The patent's summary explicitly mentions, "An exemplary technique is to include D in the TXOP descriptor transmitted in the MAP so that all nodes know in advance what value of D is used for that TXOP." The use of MAP (Media Access Plan) frames and TXOP (Transmission Opportunity) descriptors for conveying control information in managed wireless networks (like WiMAX, mentioned in the background) is conventional. Therefore, signaling the dynamically chosen header repetition factor 'D' (which dictates 2 or 4 OFDM symbols for header information) within a MAP frame's TXOP descriptor would be an obvious implementation detail for managing variable header repetition in a network.
• Claims 7, 17 (Different Channel Bandwidths): The patent clearly articulates the problem related to different bandwidths: "For the power-line medium, G.9960 has defined two overlapped baseband bandplans, 50 MHz-PB and 100 MHz-PB. The possibility of having narrower bandplans such as 25 MHz-PB and 12.5 MHz-PB are under discussion... the level of frequency diversity is different depending on the bandplan, hence providing different header decodability if D is fixed to 1." Applying the variable repetition scheme (less robust for wider bandwidths, more robust for narrower bandwidths) to optimize performance across different channel bandwidths is a direct and obvious response to this identified problem.
• Claims 10, 20 (Communication Between Different Transceivers): The patent is directed to "multi-user communications systems" and a "domain where nodes are operating in different portions of frequency bands." It is inherently obvious that different packet types with varying header repetition schemes would be used for communication between different transceivers in such a multi-user environment, based on their capabilities or channel conditions.

In summary, the specific configurations of header repetition, the use of extended headers, and the application of bit reordering for diversity, particularly in the context of different channel bandwidths and signaling via MAP frames, would have been obvious to a PHOSITA by combining the teachings of ITU G.9960 and its associated G.hn temporary documents with common general knowledge in wireless OFDM system design.