Uplink Power Control Across Mixed TTI Durations
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Solution Overview
Problem
Future radio communication systems face challenges in appropriately controlling transmission power of uplink signals at TTIs of different time durations, as existing LTE systems' power control methods are not suitable for dynamically switching between long and short TTIs without reconfiguring Radio Resource Control.
Innovation Solution
A user terminal and radio communication method that controls transmission power of uplink signals by dynamically switching between long and short TTIs using L1/L2 signaling, with accumulation control of Transmission Power Control (TPC) commands for both TTI types, allowing independent or shared accumulation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing LTE power control methods are used, then power control is simple and straightforward, but power control becomes inappropriate when dynamically switching between long and short TTIs
Solution Approach 1:
The patent implements dynamic TTI duration switching by introducing a TTI duration indication field in downlink control information (DCI), allowing the system to dynamically switch between long TTI (1ms) and short TTI configurations without reconfiguring Radio Resource Control. This enables the power control mechanism to adapt to different TTI durations in real-time, resolving the contradiction between adaptability and complexity by making the system dynamically configurable rather than statically complex.
Solution Approach 2:
The patent changes the TTI duration parameter dynamically by introducing a TTI duration indication field that can take different values (e.g., 0 for long TTI, 1 for short TTI). This parameter change mechanism allows the power control to adjust to different TTI durations by modifying the time duration parameter, enabling adaptability without requiring complete reconfiguration of the power control system.
2Speed
If TTI duration is dynamically switched using L1/L2 signaling, then switching speed is fast and RRC reconfiguration is avoided, but power control becomes challenging across different TTI types
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple TTI duration patterns (first TTI duration and second TTI duration) and their corresponding power control parameters before actual transmission. The TTI duration indication field in DCI allows rapid switching between these pre-configured patterns, enabling fast TTI switching while maintaining reliable power control through pre-established parameter sets for each TTI type.
Solution Approach 2:
The patent introduces a TTI duration indication field as an intermediary mechanism in the DCI that mediates between the fast switching requirement and reliable power control. This intermediary field carries the TTI duration information that enables the receiver to correctly interpret and apply the appropriate power control parameters for the current TTI type, ensuring reliability during rapid switching.
3Ease of manufacture
If a single power control method is used for all TTIs, then implementation is simple, but transmission power is not appropriately controlled for different TTI durations
Solution Approach 1:
The patent segments the power control mechanism into separate handling for different TTI durations by introducing a TTI duration indication field that distinguishes between first TTI duration and second TTI duration. This segmentation allows the system to apply appropriate power control parameters for each TTI type while maintaining a unified overall framework, achieving precision without sacrificing implementation simplicity through modular design.
Solution Approach 2:
The patent applies local quality by allowing different power control parameters to be applied locally to different TTI durations based on the TTI duration indication field. This enables precise power control tailored to each TTI type (long TTI vs. short TTI) while maintaining a simple overall implementation structure through conditional parameter selection based on the indication field value.
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
Transmission power of UL signals at a plurality of TTIs of different time durations is appropriately controlled. A user terminal according to the present invention includes: a receiving section that receives a Transmission Power Control (TPC) command for a first UpLink (UL) signal transmitted at a first Transmission Time Interval (TTI) and/or a TPC command for a second UL signal transmitted at a second TTI having a shorter time duration than the first TTI; and a control section that controls accumulation of the TPC command for the first UL signal and/or the TPC command for the second UL signal.