Value Delivered
The client was able to identify a strong prior-art reference that disclosed the core inventive concept: selecting HARQ-ACK feedback granularity based on the PDSCH scheduling search space.
The discovered reference established the relationship between:
- Common Search Space (CSS) scheduling and compact, single-bit Transport Block (TB)-level HARQ-ACK feedback.
- UE-specific Search Space (USS) scheduling and detailed multi-bit Code Block Group (CBG)-level HARQ-ACK feedback.
The key value came from identifying that the search space type itself could determine the HARQ feedback granularity without requiring additional control signaling. This provided the client with a Tier-1 prior-art result that directly addressed the novelty of the invention.
Problem Solved
The challenge was not the absence of relevant technical information. Existing searches, including AI-assisted searches, were able to identify individual concepts such as:
- CBG feedback
- HARQ bundling
- CSS/USS search spaces
- Physical Uplink Control Channel (PUCCH) formats
However, the missing piece was the logical connection between these elements. No clear reference was found that directly tied the search-space type to the HARQ feedback granularity rule in a single disclosure. The challenge was therefore a lack of logical closure rather than a lack of available data.
The research challenge was to move beyond keyword matching and understand the system dependency:
- PDSCH is scheduled through Downlink Control Information (DCI).
- DCI is monitored within a search space.
- HARQ feedback must correspond to the scheduling context.
The team needed to identify where the relationship between CSS/USS scheduling and HARQ-ACK feedback behavior would naturally exist in the technical architecture.
Solution Offered
The research approach shifted from searching around feedback terminology to tracing the system architecture.
The team introduced a new search path centered around DCI formats and investigated:
- 3GPP contributions discussing DCI-based PDSCH scheduling.
- Contributor portfolios, including relevant NTT documents.
- Search-space mapping between CSS and USS.
- The relationship between TB-level and CBG-level HARQ feedback.
This investigative pivot uncovered the missing connection. The identified prior art showed that:
- CSS scheduling uses compact single-bit HARQ-ACK feedback.
- USS scheduling uses detailed CBG-level multi-bit HARQ-ACK feedback.
- The scheduling search-space difference itself defines the feedback behavior without additional signaling.
The outcome demonstrated that the strongest prior art was not found by matching claim language alone, but by following hidden system dependencies and understanding how different protocol components interact.
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