Aggregated DCI for Shortened TTI Resource Efficiency
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Solution Overview
Problem
When the transmission time interval (TTI) length is shortened, the base station needs to transmit downlink control information (DCI) for each TTI to notify terminals of resource allocation and modulation and coding scheme (MCS), leading to an increase in control signal resources and reduced system throughput.
Innovation Solution
A base station and terminal system that generates and transmits a single piece of DCI containing control information for multiple shortened TTIs, where control information on retransmission processing is configured for each TTI, and other control information is shared among TTIs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If DCI is transmitted for each shortened TTI, then resource allocation and MCS notification are achieved, but control signal resources increase and system throughput decreases
Solution Approach 1:
The patent combines multiple DCI messages intended for different shortened TTIs into a single aggregated DCI message. This aggregation merges control information for multiple TTIs, reducing the total number of control signal transmissions and freeing up resource blocks that would otherwise be dedicated to control channels, thereby improving system throughput while maintaining proper resource allocation notification functionality.
Solution Approach 2:
The aggregated DCI message serves multiple functions simultaneously: it notifies resource allocation for multiple TTIs, provides MCS information, and maintains backward compatibility with existing DCI formats. This multi-functionality allows a single control message to replace multiple individual DCI transmissions, reducing control overhead while preserving all necessary control operations.
2Loss of time
If TTI length is shortened, then latency is reduced and CQI reporting frequency increases, but control signal proportion increases
Solution Approach 1:
By aggregating DCI messages for multiple shortened TTIs into one control message, the patent reduces the total quantity of control signals transmitted. This merging approach maintains the low latency benefits of shortened TTIs while counteracting the increase in control signal overhead that would otherwise consume valuable radio resources.
3Loss of information
If DCI amount is kept equal to traditional TTI, then control information completeness is maintained, but number of DCI messages increases
Solution Approach 1:
The patent merges control information for multiple TTIs into a single DCI message structure, maintaining all necessary control information elements (resource allocation, MCS, HARQ acknowledgments) while reducing the total number of separate DCI messages from four (one per TTI) to one aggregated message, thereby simplifying system complexity.
Data Source
AI summary
A base station is disclosed that enables an efficient use of resources even when a TTI length is shortened. In this base station, a PDCCH section (103) generates one piece of downlink control information (DCI) containing control information for a plurality of first transmission time intervals (TTIs) each having a TTI length shorter than a second TTI, and a transmission section (107) transmits the DCI. Control information on retransmission processing for a data signal is configured for each of the plurality of first TTIs while control information other than the control information on the retransmission processing is configured in common among the plurality of first TTIs in the DCI.