Obviousness

Obviousness Analysis of US Patent 10911186 under 35 U.S.C. § 103

This analysis identifies combinations of prior art references that would render the claims of US patent 10911186 obvious to a person having ordinary skill in the art (PHOSITA) as of its priority date (2015-03-04).

Combination of Prior Art References: IEEE 802.11ac in view of the general understanding of Block ACKs, trigger frames for multi-user uplink (MU-UL) transmission, and padding for transmission alignment (as described in the patent itself for uplink data).

Rationale for Obviousness:

A person having ordinary skill in the art (PHOSITA) in the field of wireless local area networks (WLANs) at the time of the invention would have been familiar with the IEEE 802.11 standards and ongoing developments in "next-generation wireless LAN standards" [cite: next-generation wireless LAN standards]. This environment was characterized by efforts to achieve "high-efficiency and high-performance wireless LAN communication technology in a high-density environment" [cite: next-generation wireless LAN standards].

1. Multi-User Communication Context: IEEE 802.11ac, a prior art standard, already supported "multi-user MIMO" and aimed at "high-density modulation," extending concepts like wider wireless frequency bandwidths and more MIMO spatial streams to enable simultaneous wireless LAN speeds for multiple stations [cite: IEEE 802.11ac]. This established the foundational understanding and motivation for managing simultaneous transmissions involving an Access Point (AP) and multiple stations (STAs), including multi-user uplink transmissions. [cite: FIG. 8]

2. Trigger Frames for MU-UL: The patent itself acknowledges that "the multi-user uplink transmission in a non-legacy wireless LAN system may be initiated by a trigger frame." [cite: FIG. 16] This indicates that the concept of an AP transmitting a trigger frame to initiate and coordinate a multi-user uplink transmission was a known or emerging mechanism in the art for efficiently managing shared wireless resources.

3. Reception of MU-UL Data via Allocated Resources: As a natural consequence of initiating a multi-user uplink transmission, the AP would be configured to receive multi-user uplink data from the plurality of terminals through specific "resources" (e.g., channels or sub-channels) allocated for this purpose. This resource allocation and reception mechanism is inherent in multi-user communication systems. [cite: FIG. 9]

4. Block Acknowledgments (ACKs): Block ACKs (BA) were a well-established feature in IEEE 802.11 standards (e.g., introduced in 802.11e) designed to enhance efficiency by allowing a single acknowledgment frame to confirm the reception of multiple data frames. The patent describes the "multiplexed group ACK" as potentially having a "frame format of a block ACK (BA)," further confirming its prior art status and common use for acknowledging multiple transmissions. [cite: FIG. 17] A PHOSITA would routinely use Block ACKs to respond to multi-user uplink data transmissions.

5. Motivation for Simultaneous Termination and Padding for Time Alignment: The patent clearly identifies a problem in multi-user transmissions where "the air time during which actual uplink data transmission is performed may be different for each channel." This leads to an inefficiency where "if the AP cannot simultaneously perform data transmission and reception, the AP cannot transmit an ACK through another channel in which uplink data transmission has been completed while receiving uplink data through a channel in which the air time is long," thereby lowering overall spectral efficiency. [cite: FIG. 9]

   Crucially, the patent explicitly describes a solution for uplink data transmission where "the STAs using the channel in which the air time is short may perform zero padding until the uplink data transmission of a channel having the longest air time is completed, to wait for ACK reception (S 250). That is, the padding is performed on the uplink data transmitted through at least one channel, so that the multi-user uplink data transmission in each channel can be terminated at the same time." [cite: FIG. 9]

   Given this clear understanding in the art (and acknowledged by the patent itself) that padding could be used to align the termination times of uplink data transmissions across different resources to solve the problem of staggered durations, it would have been an obvious extension for a PHOSITA to apply the same concept of padding to align the termination times of downlink Block ACK transmissions from the AP. The motivation would be identical: to address the inefficiencies and potential "malfunction of the wireless LAN network" caused by staggered response times, and to "secure transmission time of a control frame of an AP," as stated in the patent's advantageous effects. [cite: Advantageous Effects]

The choice of specific padding (e.g., zero padding, or "duplicated ACK information" as mentioned in a dependent embodiment [cite: another embodiment]) to achieve this length alignment would be a routine engineering decision based on implementation specifics and desired trade-offs for a PHOSITA already familiar with padding techniques for time synchronization in wireless communication.

Therefore, the combination of established multi-user communication principles (IEEE 802.11ac), standard acknowledgment mechanisms (Block ACKs), trigger frames for initiating MU-UL, and the known technique of padding for transmission alignment (as directly taught by the patent for uplink data in FIG. 9) would have rendered the claims of US patent 10911186 obvious to a PHOSITA.