Shortened TTI Random Access Timing Control
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Solution Overview
Problem
In next-generation mobile communication systems, particularly after LTE Rel. 13, there is a need for effective timing control when using shortened transmission time intervals (TTIs) to reduce communication latency, especially for high-frequency bands and applications like IoT, MTC, M2M, D2D, and V2V, which require low-delay communication.
Innovation Solution
A user terminal and radio base station configuration that allows for appropriate timing control using shortened TTIs, with a receiving section for DL signals and a control section for UL signal transmission, enabling control of random access procedures based on both shortened and normal TTIs with durations of one ms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If shortened TTIs are used to reduce communication latency, then communication speed and responsiveness are improved, but timing control complexity increases
Solution Approach 1:
The patent applies dynamics by making the TTI duration adjustable and configurable rather than fixed. The system can dynamically switch between shortened TTIs (e.g., 0.5ms, 0.25ms) and normal TTIs (1ms) based on service requirements, allowing the timing control mechanism to adapt to different communication scenarios while managing complexity through flexible configuration.
Solution Approach 2:
The invention changes the TTI duration parameter from a fixed 1ms value to multiple configurable values including shortened durations. By modifying this key parameter, the system achieves reduced communication latency for time-sensitive applications while maintaining the ability to use longer durations for other services, thus balancing performance improvement with controlled complexity.
2Productivity
If shortened TTIs are used to increase user terminal capacity per unit time, then productivity is improved, but processing complexity increases
Solution Approach 1:
The patent segments the time domain into multiple shorter TTI units. By dividing the traditional 1ms TTI into shorter intervals (e.g., 0.5ms, 0.25ms), the system can schedule more user terminals within the same time frame, thereby increasing overall system capacity and productivity while managing processing complexity through structured time division.
3Speed
If shortened TTIs are used for random access procedures, then access speed is improved, but compatibility with existing systems deteriorates
Solution Approach 1:
The patent implements a universal timing control mechanism that can handle both shortened TTIs and normal 1ms TTIs within the same random access procedure framework. The system maintains compatibility with existing LTE systems by supporting the traditional TTI duration while simultaneously enabling shortened TTIs for enhanced performance, thus achieving multi-functionality and broad adaptability.
Data Source
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Figure 3A~3B
AI summary
The present invention is designed so that adequate timing control is allowed even when shortened TTIs are used. A user terminal communicates using a shortened transmission time interval (TTI), in which the TTI duration is shorter than one ms, and has a receiving section that receives a DL signal transmitted from the radio base station, and a control section that controls transmission of a UL signal based on the DL signal, and the control section controls a random access procedure based on the shortened TTI and/or a normal TTI having a TTI duration of one ms.