Single DCI Multi-TTI Scheduling for 5G Control Overhead
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Solution Overview
Problem
Current 5G systems face challenges in cross-carrier scheduling, particularly when the subcarrier spacing of the scheduling carrier is smaller than that of the scheduled carrier, as existing methods do not effectively support multi-slot scheduling in such scenarios.
Innovation Solution
The method involves scheduling traffic channels in multiple transmission time intervals (TTIs) through a single downlink control information (DCI), where the subcarrier spacing of the scheduled traffic channel is not smaller than that of the scheduling carrier, allowing for efficient transmission of DCI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple DCIs are used to schedule traffic channels in multiple slots, then scheduling flexibility is improved, but control channel overhead increases and complexity increases
Solution Approach 1:
The patent merges multiple scheduling decisions into a single DCI message. Specifically, one DCI schedules traffic channels across multiple slots by indicating a time domain resource allocation that spans multiple slots, thereby consolidating what would otherwise require multiple separate DCIs into a single control message, reducing overhead while maintaining scheduling flexibility
Solution Approach 2:
The DCI structure is enhanced to perform multiple functions simultaneously: it schedules traffic channels not only within the same slot but also across multiple slots with different subcarrier spacings. This multi-functional DCI can indicate both frequency domain resource allocation and time domain spanning multiple slots, making a single DCI versatile enough to replace multiple specialized DCIs
2Adaptability or versatility
If cross-carrier scheduling is implemented between carriers with different subcarrier spacings, then system adaptability is improved, but scheduling complexity increases
Solution Approach 1:
The patent changes the parameters indicated in the DCI to accommodate different subcarrier spacings. The time domain resource allocation field in the DCI is designed to indicate slot offsets and durations that are interpreted relative to the scheduled carrier's subcarrier spacing, allowing the same DCI structure to work across carriers with different SCS values without requiring separate scheduling mechanisms
Solution Approach 2:
The DCI acts as an intermediary that bridges carriers with different subcarrier spacings. By including explicit time domain resource allocation information that specifies slot offsets and durations, the DCI mediates the scheduling between the scheduling carrier and scheduled carrier with different SCS, translating scheduling intentions into actionable resource allocations that account for the subcarrier spacing difference
3Device complexity
If a single DCI schedules multiple slots, then control channel overhead is reduced, but scheduling precision requirements increase
Solution Approach 1:
The time domain resource allocation indication in the DCI is segmented into multiple fields: a first indication field for slot offset, a second indication field for slot duration, and potentially a third field for symbol-level allocation within slots. This segmentation allows precise specification of multiple slots while keeping each individual field manageable in size, achieving both compact DCI structure and high scheduling precision
Solution Approach 2:
The patent adds temporal dimension to the resource allocation by indicating not just frequency resources but also time spanning multiple slots. The DCI includes time domain resource allocation information that specifies which slots and symbols are allocated, adding the time dimension to the traditional frequency-only resource allocation, thereby enabling precise multi-slot scheduling within a single DCI
Data Source
AI summary
Method and apparatus for transmitting downlink control information (DCI) are provided. The method includes: scheduling traffic channels in multiple transmission time intervals (TTIs) through a single DCI; wherein the scheduling the traffic channels in the plurality of TTIs through the single DCI comprises: indicating, through one bit-field in the single DCI, a number of TTIs and a number of repetitions of a multi-TTI scheduling.