PUSCH Control Signaling for Short TTI Latency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current LTE systems face challenges in reducing latency for uplink data transmission on the Physical Uplink Shared Channel (PUSCH) due to increased overhead from frequent transmission of downlink control information and uplink demodulation reference signals, especially with shorter Time Transmission Intervals (TTIs), which complicates processing and efficiency.
Innovation Solution
The solution involves dividing downlink control information into two parts: a slow transmission on the legacy Physical Downlink Control Channel (PDCCH) or Enhanced PDCCH for initial configuration, and mini DCIs transmitted more frequently for each short TTI, along with conditional UL grants and dynamic DMRS allocation to minimize overhead and maintain compatibility with existing systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If frequent transmission of downlink control information is performed for short TTI, then latency is reduced, but overhead increases
Solution Approach 1:
The downlink control information is segmented into two parts: a first part transmitted periodically on the legacy PDCCH/E-PDCCH for initial configuration, and a second part (mini DCI) transmitted frequently on the control channel for each short TTI to provide updated scheduling information. This segmentation allows the system to maintain low latency through frequent mini DCI transmissions while reducing overall overhead by avoiding redundant transmission of the complete control information set.
2Productivity
If frequent transmission of downlink control information is performed for short TTI, then responsiveness is improved, but processing complexity increases
Solution Approach 1:
The control information is divided into a first part containing initial configuration parameters and a second part (mini DCI) containing only the essential scheduling updates for each short TTI. This segmentation enables the UE to process only the critical updates in the mini DCI for each short TTI while maintaining the broader context from the first part, thereby improving responsiveness without proportionally increasing processing complexity.
Solution Approach 2:
The first part of the downlink control information is transmitted periodically in advance to establish the initial configuration and context. This preliminary action allows the UE to have the necessary background information ready before the frequent mini DCI transmissions occur, simplifying the processing required for each short TTI since the UE only needs to process the updates in the mini DCI rather than the complete control information set from scratch.
3Productivity
If conditional PUSCH allocation and flexible DMRS placement are implemented, then system efficiency is enhanced, but compatibility with existing systems is challenged
Solution Approach 1:
The control channel is designed to transmit both the first part of downlink control information (compatible with existing LTE structures) and the second part (mini DCI for short TTI) within the same framework. This multi-functionality allows the system to maintain compatibility with existing LTE devices while enabling the enhanced short TTI PUSCH allocation and flexible DMRS placement features that improve system efficiency.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method and apparatus may include receiving a first signal. The first signal includes first configuration information, second configuration information, and third configuration information. The method may also include detecting a second signal based on the first configuration information. The method may also include transmitting a third signal based on the second configuration information. The method may also include transmitting a fourth signal based on the third configuration information and the detected second signal.