Obviousness

Obviousness Analysis under 35 U.S.C. § 103 for US Patent 10306667

This analysis assesses the obviousness of US patent 10306667, focusing on its independent claims (Claims 1, 9, and 12), by identifying combinations of prior art references that would render the claims obvious to a Person Having Ordinary Skill in the Art (PHOSITA) at the time of the invention (priority date: February 17, 2016).

Identified Problem and Proposed Solution

US patent 10306667 addresses a problem in Wireless Local Area Network (WLAN) systems, particularly within the context of IEEE 802.11ax (High Efficiency, HE) standards, which support multi-user (MU) transmissions. According to the patent, while uplink (UL) multi-user transmissions are typically scheduled by an Access Point (AP) using a dedicated "trigger frame," using a separate trigger frame to receive acknowledgment (ACK) signals in response to downlink (DL) multi-user data causes "delay in the process or unnecessary signaling overhead." [cite: 'if the AP transmits a PPDU for downlink multi-user transmission and a separate trigger frame to receive an acknowledgement signal in response to the PPDU in a multi-user manner as well, it may cause a delay in the process or unnecessary signaling overhead.']

To solve this, the patent proposes transmitting uplink scheduling information (UL trigger information) by including it directly in the downlink Physical Protocol Data Unit (DL PPDU) when data is transmitted in a DL MU manner. [cite: 'To solve this problem, it is proposed in an embodiment of the present invention to transmit UL trigger information by including it in a DL PPDU when data is transmitted in a DL MU manner as shown in FIG. 6.']

Prior Art References for Combination

The following prior art references, as cited in US10306667, are relevant for an obviousness analysis:

• US10306667 (the patent itself): Provides comprehensive background on WLAN operation (FIG. 1), the multi-user transmission scheme in HE systems (FIG. 2), and detailed descriptions of trigger frame formats for uplink scheduling (FIGS. 3-5). Crucially, it explicitly identifies the problem (signaling overhead/delay) and the motivation for improvement. [cite: 'FIG. 1 is a diagram for explaining a general data transmission method for STAs in a WLAN system.', 'FIG. 2 is a diagram for explaining an example of uplink multi-user transmission in an HE system.', 'FIGS. 3 to 5 are diagrams for explaining trigger frame formats used in an HE system.', 'if the AP transmits a PPDU for downlink multi-user transmission and a separate trigger frame to receive an acknowledgement signal in response to the PPDU in a multi-user manner as well, it may cause a delay in the process or unnecessary signaling overhead.']
• Stacey, R., "Specification Framework for TGax", IEEE P802.11 Wireless LANs, doc.: IEEE 80211-15/0132r15, Jan. 2016: This non-patent literature (NPL) outlines the specification framework for the IEEE 802.11ax standard (TGax/HE system), confirming the state of the art regarding multi-user operations and frame structures.
• Porat, R. et al., "SIG-A Fields and Bitwidths", doc.: IEEE 802.11-15/1354r1, Nov. 2015: This NPL likely details the structure and use of the HE-SIG-A field, a critical control information subfield within PPDUs in 802.11ax, which is relevant to embedding scheduling information.
• US20170255659A1 (Intel IP Corp.), filed Jan 29, 2016: Titled "Basic service set identifications for using non-default spatial reuse parameters," this patent application indicates that spatial reuse and its associated signaling were known and actively being optimized in WLAN systems around the priority date of US10306667. [cite: 'Basic service set identifications for using non-default spatial reuse parameters']

Obviousness Argument

A PHOSITA in the field of WLAN systems, particularly those working on the IEEE 802.11ax standard, would have possessed the following knowledge at the time of the invention:

1. Downlink Multi-User (DL MU) Transmissions: It was known that APs transmit data to multiple STAs in a downlink multi-user manner in HE systems. [cite: 'an IEEE 802.11 ax system (hereinafter referred to as a high efficiency (HE) system) uses a multi-user transmission scheme where a plurality of STAs transmit data to an access point (AP) in uplink and the AP transmits data to the plurality of STAs in downlink']
2. Uplink Multi-User (UL MU) Scheduled by Trigger Frames: It was established that APs initiate and schedule UL MU transmissions from multiple STAs using dedicated "trigger frames," which contain essential scheduling information such as Resource Unit (RU) allocation, Modulation and Coding Scheme (MCS), and other parameters. [cite: 'An uplink (UL) multi-user (MU) transmission scheme can be used in the HE system as described above, and an AP can transmit trigger frames to a plurality of STAs (e.g., STA 1 to STA 4 ) to initiate the UL MU transmission.', 'the trigger frame may include UL MU allocation information (e.g., resource location and size, STA IDs, MCS, MU type (e.g., MIMO, OFDMA, etc.)).', 'FIGS. 3 to 5 are diagrams for explaining trigger frame formats used in an HE system.'] These trigger frame mechanisms are explicitly described in US10306667 (FIGS. 2-5) and would be detailed in NPLs like Stacey (2016).
3. Acknowledgement (ACK) for Reliability: ACKs are fundamental to WLAN reliability, with STAs sending ACKs for received data (e.g., FIG. 1 of US10306667). [cite: 'the second STA may transmit an acknowledgement (ACK) frame after receiving the data transmitted from the first STA.']
4. Control Information Subfields in PPDUs: PPDUs are known to contain various control information subfields, such as the HE-SIG-A field in 802.11ax. NPLs like Porat (2015) would describe the structure and function of such fields. The patent also notes the use of an "A-control subfield, which is currently used in the WLAN system." [cite: 'However, embodiments of the present invention are described based on the method of using an A-control subfield, which is currently used in the WLAN system.']

Motivation for Combination

The patent itself provides the explicit motivation for a PHOSITA to combine these known elements: to overcome the "delay in the process or unnecessary signaling overhead" caused by sending a separate trigger frame for scheduling ACK signals in response to DL MU data. [cite: 'if the AP transmits a PPDU for downlink multi-user transmission and a separate trigger frame to receive an acknowledgement signal in response to the PPDU in a multi-user manner as well, it may cause a delay in the process or unnecessary signaling overhead.'] A PHOSITA would inherently be motivated to reduce such inefficiencies.

Combination Rationale for Independent Claims

Claims 1 (STA Method) and 12 (AP Method):
Given the recognized problem and the existing mechanism for UL scheduling via trigger frames (known from US10306667 FIGS. 2-5, and NPLs like Stacey), a PHOSITA would find it obvious to integrate the uplink scheduling information required for ACK responses directly into the downlink PPDU that carries the data being acknowledged. This would eliminate the need for a separate trigger frame and thereby reduce overhead and delay.

The specific parameters listed in the control information subfield (length information of the UL PPDU, RU allocation, MCS information, AP transmit power, and target RSSI of the AP) are all standard scheduling parameters already present in or inferable from trigger frames used for general UL MU transmissions (e.g., as described in US10306667 FIGS. 4 and 5 for trigger frames). Embedding these parameters into an existing control subfield within the DL PPDU (e.g., an A-Control subfield or HE-SIG-A field, as discussed in the patent and by Porat) would be a straightforward engineering adaptation to achieve the desired efficiency gains.

The "disabling spatial reuse" limitation:
Claim 1 and 12 also specify that the control information subfield does not include spatial reuse information, and the STA (or AP processing) is configured to disable spatial reuse for the uplink PPDU. The patent itself explains the rationale: "the gain obtained by applying the spatial reuse to ACK/BA-M-BA transmission for UL MU data transmission is not greater than that obtained by saving the space for signaling." [cite: 'However, the gain obtained by applying the spatial reuse to ACK/BA-M-BA transmission for UL MU data transmission is not greater than that obtained by saving the space for signaling.'] This indicates that spatial reuse and the trade-offs involved were known in the art. US20170255659A1, prior to the priority date, confirms active work on spatial reuse parameters. A PHOSITA, striving for efficiency, would readily understand and implement such a trade-off for short, critical messages like ACKs, deciding to omit spatial reuse signaling and disable the feature to save bits, especially when the benefits are marginal for such traffic.

Claim 9 (STA Apparatus):
Claim 9 describes an STA apparatus comprising a transceiver and a processor configured to perform the method of Claim 1. Given that the method described in Claim 1 is deemed obvious, configuring a standard STA processor and transceiver (components widely known in the art, as illustrated generally in US10306667 FIG. 11) to implement this obvious method would also be an obvious step for a PHOSITA. No specialized hardware beyond standard WLAN components is required, only a reprogramming or configuration of existing elements.

Conclusion

The independent claims of US patent 10306667, particularly the core invention of embedding uplink scheduling information for acknowledgements directly within a downlink PPDU, would have been obvious to a PHOSITA. The motivation for this combination is explicitly stated in the patent itself: to reduce the signaling overhead and delay associated with using a separate trigger frame for ACK responses in a multi-user WLAN environment. The specific elements of the scheduling information and the decision to disable spatial reuse are either standard parameters from existing trigger frame mechanisms or known engineering trade-offs in WLAN optimization. Combining the knowledge of existing multi-user transmission schemes, trigger frame functionality (as described in US10306667 and NPLs like Stacey), and the purpose and structure of PPDU control subfields (as discussed in US10306667 and NPLs like Porat), with the clear motivation to improve efficiency, would lead a PHOSITA to the claimed invention.