Obviousness

Obviousness Analysis of US Patent 11368911 under 35 U.S.C. § 103

This analysis evaluates the obviousness of US patent 11368911, specifically claims 1 (method) and 10 (apparatus), by combining teachings from relevant prior art references. The Person Having Ordinary Skill in the Art (PHOSITA) is presumed to be an engineer or researcher knowledgeable in 3GPP wireless communication standards, particularly concerning power saving mechanisms in New Radio (NR) and Long Term Evolution (LTE) systems, including Discontinuous Reception (DRX) and Physical Downlink Control Channel (PDCCH) monitoring.

Independent Claims Overview (Recap)

• Claim 1 (Method): This claim describes a method for a User Equipment (UE) to monitor a PDCCH by:
  1. Receiving a first configuration for a first search space to monitor scheduling signals.
  2. Receiving a second configuration for a second search space to monitor a power saving signal (WUS) indicating wake-up information for DRX.
  3. Starting a DRX on-duration timer if the power saving signal is not received while monitoring the second search space.
  4. Monitoring the first search space when the UE is in DRX active time.
  5. Critically, not monitoring the second search space when the UE is in DRX active time.
• Claim 10 (Apparatus): This claim covers a UE comprising a processor and memory configured to perform the method steps of Claim 1.

Prior Art Background

Prior to the filing date of US11368911 (April 27, 2020), the concepts of DRX for UE power saving and Wake-Up Signals (WUS) were well-established and actively discussed within 3GPP for 5G NR.

1. Discontinuous Reception (DRX): DRX is a fundamental power-saving mechanism in RRC_CONNECTED mode, allowing a UE to periodically wake up during "on-duration" periods to monitor the PDCCH for scheduling grants and then return to a sleep state. This mechanism significantly reduces power consumption compared to continuous monitoring. The DRX active time, including the on-duration and periods influenced by timers like drx-InactivityTimer, designates when the UE is actively monitoring the PDCCH for scheduling signals.
2. Wake-Up Signals (WUS): The WUS was introduced in 3GPP Release 16 (and earlier in LTE for LPWA devices) as an enhancement to DRX, aiming to further reduce unnecessary PDCCH monitoring. A WUS is typically sent by the network before a scheduled DRX on-duration. If the UE successfully receives the WUS, it proceeds to monitor the PDCCH during the upcoming on-duration. If the WUS is not received, the UE can infer that no data is pending and can skip the entire on-duration period, remaining in a deeper sleep state to save power.
3. Dedicated Search Spaces: Both standard PDCCH monitoring for scheduling and WUS monitoring are performed within configured search spaces or Control Resource Sets (CORESETs). US20180332533A1, for instance, explicitly discusses a UE periodically awakening to monitor for a WUS in a "wake-up signal search space."

Obviousness Argument

The claimed invention in US11368911 primarily differentiates itself by two specific behaviors: (1) not monitoring the WUS search space when the UE is already in DRX active time, and (2) starting a DRX on-duration timer if the WUS is not received while monitoring the second search space.

Combination of Prior Art References

A persuasive combination of prior art that would render Claims 1 and 10 obvious includes:

1. US20180332533A1 (Qualcomm): This patent application, with a priority date of May 15, 2017, explicitly teaches a UE periodically awakening to monitor for a Wake-Up Signal (WUS) in a "wake-up signal search space." The WUS is designed to inform the UE whether it should monitor for a control channel communication. This reference clearly establishes the concept of a dedicated search space for a power-saving (wake-up) signal.
2. General knowledge of DRX operation in NR/LTE (e.g., Huawei BLOG, Ericsson, EE World Online): These and numerous other sources detail the conventional DRX mechanism, including the "DRX active time" during which the UE monitors the PDCCH for scheduling grants. This active time typically involves the drx-onDurationTimer and drx-InactivityTimer being active, during which the UE is fully powered up for PDCCH monitoring.

Motivation for Combination

The motivation for a PHOSITA to combine the teachings of a dedicated WUS search space with conventional DRX operation to arrive at the claimed invention is rooted in the widely recognized problem of unnecessary power consumption due to redundant monitoring and the inherent design goal of WUS: to save power.

The '911 patent's own background section (and related art references) highlights the issue: "the running drx-InactivityTimer may keep the UE awake even without PDCCH scheduling, or whether or not there is PDCCH scheduling, the drx-onDurationTimer may still periodically trigger the UE to wake up. This situation may be called PDCCH-only monitoring... which causes unnecessary power consumption in RRC connected mode." Furthermore, the patent acknowledges the scenario where "the time domain of the CORESET (or search space) for the WUS may collide with the CORESET (or search space) for scheduling by the PDCCH, as shown in FIG. 3." This collision during DRX active time would lead to the UE simultaneously monitoring both search spaces, which is explicitly identified as increasing power consumption.

The overarching motivation for implementing WUS in 5G NR is to reduce UE power consumption by allowing the UE to skip PDCCH monitoring when no data is expected.

• "Not monitoring the second search space in response to the UE being in the DRX active time":
  A PHOSITA, observing the known collision scenarios (as illustrated in prior art diagrams like FIG. 3 and FIG. 4 of the '911 patent itself, described as "related art methods") and understanding the fundamental purpose of WUS, would be logically motivated to prevent redundant monitoring. If the UE is already in "DRX active time" (i.e., actively monitoring the PDCCH for scheduling signals), its primary receiver is already awake and consuming power. In this state, monitoring a wake-up signal becomes redundant and unnecessary, as the UE is already "awake." The '911 patent itself explicitly articulates this motivation: "if the UE is already in the DRX active time, it is unnecessary to monitor the WUS. Thus, the UE may not need to monitor the WUS when the UE is in DRX active time, so as to reduce the power consumption." This statement from the patent's detailed description serves as direct evidence of the obvious motivation to a PHOSITA. Eliminating such redundant monitoring directly contributes to the well-known goal of saving UE power.

• "In response to not receiving the power saving signal while monitoring the second search space, starting a DRX on-duration timer":
  The prior art (e.g., Nokia, Huawei BLOG, arXiv) teaches that if the WUS is not received, the UE can skip the on-duration. This implies a decision point. Conversely, if the network has configured the WUS as an advisory signal, or if a robust fallback mechanism is desired such that the UE still enters its scheduled on-duration despite not detecting the WUS (e.g., due to poor WUS reception or to maintain a baseline DRX activity), then starting the drx-onDurationTimer would be a straightforward and logical design choice within the established DRX framework. The patent's own description indicates this as a possible behavior: "the UE may start or restart the drx-onDurationTimer (on a DRX cycle) when the UE does not monitor and/or receive the WUS on the WUS occasion (before the DRX cycle), or when the UE is in the DRX active time." This demonstrates that such timer management in response to WUS non-reception was a contemplated and obvious design choice for managing DRX states.

Conclusion

Given the pervasive desire to optimize UE power consumption in wireless communication, and the well-known mechanisms of DRX and WUS for achieving this, a PHOSITA would have been motivated to combine the concept of dedicated WUS search spaces (as in US20180332533A1) with the established DRX framework (as in Huawei BLOG, Ericsson, EE World Online). The explicit motivation, even stated within the US11368911 patent itself, to avoid redundant WUS monitoring when the UE is already in an active DRX state, would lead a PHOSITA to the "not monitoring the second search space" limitation. Similarly, managing the drx-onDurationTimer based on WUS reception or non-reception represents a logical design choice or fallback mechanism within the known DRX operation to balance power saving with network reachability.

Therefore, the methods of Claim 1 and the apparatus of Claim 10 of US11368911 would have been obvious to a PHOSITA at the time of the invention.