User Terminal Short TTI Embedding for Latency Reduction
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Solution Overview
Problem
Future radio communication systems face challenges in achieving a satisfactory latency-reducing effect when using multiple transmission time intervals (TTIs) of different durations in the same carrier, as existing systems struggle to effectively integrate short and long TTIs for various services like eMBB, mMTC, and URLLC.
Innovation Solution
A user terminal is designed with a receiving section for shorter TTIs embedded within longer TTIs, allowing for control and scheduling of data transmission based on scheduling information, enabling efficient coexistence and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple TTIs of different time durations are used in the same carrier, then various services with different latency requirements can be supported, but a satisfactory latency-reducing effect cannot be achieved
Solution Approach 1:
The patent segments the TTI structure by introducing a short TTI (sTTI) that is embedded within or operates independently from the traditional long TTI (1ms). This segmentation allows different services to use appropriate TTI lengths: URLLC uses sTTI for low latency, while eMBB uses traditional TTI for high throughput. The sTTI can be configured as 2-7 symbols long, creating distinct time granules for different service requirements.
Solution Approach 2:
The patent implements dynamic TTI length adaptation where the system can flexibly switch between long TTI and short TTI configurations based on service requirements. The sTTI position, duration, and resource allocation are dynamically adjustable through RRC signaling and DCI formats, allowing the system to optimize latency for time-sensitive services while maintaining efficiency for other services.
2Loss of time
If short TTIs are embedded in long TTIs, then latency can be reduced for specific services, but system complexity increases
Solution Approach 1:
The patent embeds short TTIs within the structure of long TTIs, creating a nested time structure where sTTIs can be positioned at specific symbol indices within a 1ms frame. This nesting allows the system to maintain the existing long TTI framework while incorporating shorter time granules for low-latency services, reducing the need for entirely separate processing paths.
Solution Approach 2:
The patent designs the sTTI mechanism to serve multiple functions: it can be used for URLLC data transmission, sTTI-based scheduling, cross-carrier scheduling, and coexistence with legacy TTI structures. The same sTTI framework handles both downlink and uplink services, reducing the need for separate specialized mechanisms for each service type.
Data Source
AI summary
A satisfactory latency-reducing effect is achieved when a plurality of transmission time intervals (TTI) of varying time durations are used in the same carrier. In this regard, a user terminal has a receiving section that receives scheduling information pertaining to a second TTI, which is shorter than a first TTI. The user terminal further has a control section that controls receipt and/or transmission of data in the second TTI, which is embedded in the first TTI, based on the scheduling information.