PUSCH Scheduling Back-to-Back Restriction for 5G NR
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Solution Overview
Problem
Current 3GPP specifications for 5G NR do not adequately address back-to-back scheduling of PUSCHs with the same HARQ process ID, particularly for DCIs scrambled by TC-RNTI and CS-RNTI, leading to complexity in UE implementation and unsolved cases for initial transmissions and retransmissions of Msg3 and CG-PUSCH.
Innovation Solution
Proposed methods extend the restriction on PUSCH scheduling to include DCIs scrambled by TC-RNTI and CS-RNTI, ensuring that UE does not expect subsequent PUSCH transmissions until after the completion of the last PUSCH transmission for a given HARQ process, thereby simplifying UE handling and addressing the complexity of back-to-back scheduling across all relevant cases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the current 3GPP restriction on PUSCH scheduling is applied only to DCIs scrambled by C-RNTI or MCS-C-RNTI, then UE implementation complexity is reduced for those specific cases, but gaps remain in handling DCIs scrambled by TC-RNTI and CS-RNTI which require additional complexity
Solution Approach 1:
The patent extends the back-to-back scheduling restriction to apply universally across all DCI types (C-RNTI, MCS-C-RNTI, TC-RNTI, and CS-RNTI) rather than maintaining separate handling rules. This universal application eliminates the need for UE to implement separate logic for different RNTI types, reducing overall implementation complexity while achieving complete coverage of all scheduling cases.
2Productivity
If back-to-back scheduling of PUSCHs with the same HARQ process ID is allowed, then scheduling flexibility and resource utilization are improved, but UE implementation complexity increases due to need to handle multiple overlapping cases
Solution Approach 1:
The patent applies a preliminary restriction that prevents back-to-back scheduling of PUSCHs with the same HARQ process ID before the previous transmission is complete. This preventive measure eliminates the need for UE to implement complex conflict resolution logic for overlapping schedules, as the network proactively avoids creating such scenarios in the first place.
Solution Approach 2:
Instead of allowing back-to-back scheduling and managing conflicts through complex UE logic, the patent inverts the approach by prohibiting such scheduling entirely. This inversion simplifies the system by eliminating the problem rather than managing it, trading slight scheduling flexibility for significant reduction in UE complexity.
3Ease of manufacture
If separate handling rules are maintained for different RNTI types, then specific cases can be optimized, but the overall system complexity increases and gaps in coverage occur
Solution Approach 1:
The patent merges the handling rules for all RNTI types (C-RNTI, MCS-C-RNTI, TC-RNTI, CS-RNTI) into a single unified back-to-back scheduling restriction. This consolidation eliminates the need for separate case-specific logic while maintaining appropriate handling for each RNTI type, reducing overall system complexity and eliminating coverage gaps.
Data Source
AI summary
Various solutions for new procedures for physical uplink shared channel (PUSCH) scheduling in mobile communications are described. An apparatus performs a last PUSCH transmission of one or more PUSCH transmissions associated with a first hybrid automatic repeat request (HARQ) process. The apparatus also receives, after and not before the last PUSCH transmission, a downlink control information (DCI) signal scrambled by a specific radio network temporary identifier (RNTI) and scheduling a subsequent PUSCH transmission for the first HARQ process.