Wireless Carrier Aggregation TTI Reporting Method
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Solution Overview
Problem
Current wireless communication systems face challenges in reducing latency for packet data transmission and supporting carrier aggregation with multiple transmission time intervals (TTIs), which affects the efficiency of uplink data and HARQ feedback in next-generation mobile communication systems like new radio access technology (NRAT) and long-term evolution (LTE).
Innovation Solution
The proposed solution involves a method for user equipment (UE) to efficiently perform carrier aggregation by reporting capability signaling for various TTIs, allowing for flexible implementation of short TTIs (sTTIs) across different carrier combinations, enabling coordinated data transmission and improved processing times for HARQ operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If carrier aggregation with multiple TTIs is implemented, then system adaptability and latency reduction capability are improved, but device complexity and capability reporting overhead increase
Solution Approach 1:
The capability reporting is segmented into multiple independent fields: first capability information indicates support for at least two different TTI lengths, while second capability information indicates support for simultaneous reception on carriers with different TTI lengths. This segmentation allows the network to selectively activate only the capabilities needed for each specific scenario, reducing overall reporting overhead while maintaining full adaptability.
Solution Approach 2:
The system dynamically adapts TTI lengths on different carriers based on service requirements and network conditions. The UE can simultaneously operate with different TTI configurations on different carriers, and the network can flexibly configure which carriers use which TTI lengths, enabling dynamic optimization of latency versus complexity trade-offs.
2Speed
If short TTI (sTTI) is used for latency reduction, then packet data transmission speed is improved, but processing time requirements and system complexity increase
Solution Approach 1:
Different TTI lengths are assigned to different carriers based on local service requirements. sTTI is applied only where low latency is critical, while normal TTI is used where standard performance suffices. This localized application of short TTIs reduces overall processing complexity while achieving latency reduction where needed.
Solution Approach 2:
The system changes the TTI length parameter dynamically based on service type and network conditions. The UE capability reporting includes information about supported TTI length combinations, allowing the network to select appropriate parameter configurations that balance speed requirements against processing complexity.
3Adaptability or versatility
If multiple TTI lengths are supported on different carriers, then uplink transmission flexibility is improved, but capability signaling overhead increases
Solution Approach 1:
The capability signaling is divided into distinct fields: first capability information for TTI length support, second capability information for simultaneous reception support, and optionally third capability information for specific sTTI configurations. This segmentation reduces signaling overhead by allowing the network to request only the relevant capability information needed for each deployment scenario.
Solution Approach 2:
The capability reporting mechanism is designed to be universal, supporting multiple TTI configurations through a single structured reporting framework. The same capability fields can accommodate various combinations of TTI lengths and carrier configurations, eliminating the need for separate signaling for each specific scenario.
Data Source
Figure 1(a)~1(b)
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AI summary
A method for supporting carrier aggregation and a short transmission time interval (sTTI) in a wireless communication system according to an embodiment of the present invention is performed by a terminal, and may comprise a step of reporting the maximum number of component carriers supporting a combination of downlink (DL) and uplink (UL) sTTI lengths, in units of bands or band combinations.