Flexible TTI Control for Low-Delay Radio Communication

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Solution Overview

Problem

Existing LTE systems face challenges in achieving low-delay radio frames with excellent power saving performance, as they are controlled on a per subframe basis, making it difficult to satisfy the requirements of future radio communication systems that need efficient signal transmission and reception in a short time, especially in scenarios with no data to be transmitted or received.

Innovation Solution

The solution involves dynamically or semi-dynamically allocating predetermined DL and UL signals within transmission time intervals (TTIs), allowing for multiplexing of signals and control signals within the same TTI or separated TTIs, enabling shorter TTI durations and self-contained communication periods to reduce power consumption and delay.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If communication timing is controlled on a per subframe (one ms) basis as in existing LTE systems, then communication can be maintained with current standards, but it is difficult to achieve low-delay communication and excellent power saving performance required by future radio communication systems

Engineering Contradiction:
Improvecommunication delayVSAvoidcommunication control complexity
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The patent segments the communication timing control from the fixed per-subframe basis into flexible TTI-based control. By dividing the communication frame into variable-length TTIs that can be dynamically adjusted, the system achieves finer granularity in timing control, enabling low-delay communication while maintaining manageable complexity through standardized TTI structures.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic TTI configuration where the base station can flexibly adjust TTI duration and timing based on traffic conditions and service requirements. This dynamic control allows the system to adapt communication timing to achieve low delay when needed while maintaining power efficiency, resolving the contradiction between fixed timing control and flexible low-delay requirements.

Inventive Principle:
Principle #15Dynamics

2Use of energy by moving object

If signals are transmitted continuously as in existing LTE systems, then communication coverage is maintained, but power consumption increases and power saving performance deteriorates

Engineering Contradiction:
Improvepower consumptionVSAvoidcommunication availability
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The patent implements periodic transmission patterns where signals are transmitted only during necessary TTIs and remain silent during idle periods. By using periodic scheduling with variable周期的 based on traffic needs, the system achieves excellent power saving performance while maintaining communication reliability through on-demand signal transmission rather than continuous transmission.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system enables self-service power management where the base station and user equipment autonomously adjust transmission timing based on buffer status and traffic conditions. When no data needs to be transmitted, the system automatically enters low-power states without continuous monitoring, achieving power savings while maintaining communication availability through event-triggered activation.

Inventive Principle:
Principle #25Self-service

3Loss of time

If TTI duration is extended to maintain stable communication, then power saving performance improves, but feedback delay increases and low-delay communication requirements cannot be met

Engineering Contradiction:
Improvefeedback delayVSAvoidpower saving efficiency
Core Design Contradiction:
Loss of timeVSProductivity

Solution Approach 1:

The patent dynamically changes the TTI duration parameter based on service requirements and traffic conditions. By adjusting TTI length from short (for low-delay feedback) to long (for power saving), the system optimizes the trade-off between feedback delay and power saving efficiency, achieving both low-delay communication and power efficiency through adaptive parameter selection.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3879905B1User terminal, radio base station and radio communication method
Publication Date: 2023.11.15 NTT DOCOMO INC
  • EP3879905B1 patent drawingFigure 1
  • EP3879905B1 patent drawingFigure 2A~2B
  • EP3879905B1 patent drawingFigure 3A~3B

AI summary

The present invention is designed so that adequate communication can be carried out even in future radio communication systems. A user terminal communicates using a transmission time interval (TTI), which has a predetermined TTI duration, and has a receiving section that receives a DL signal, a transmission section that transmits a UL signal, and a control section that controls at least one of transmission of a random access preamble, transmission of an SRS, reception of a broadcast channel and reception of a mobility reference signal, based on downlink control information that is included in the same TTI.