User Terminal Power Control for Shortened TTI Latency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LTE systems face challenges in controlling transmission power effectively when shortened processing times are introduced, particularly with the use of 1-ms subframes, which is essential for reducing latency in future radio communication systems like 5G and NR.
Innovation Solution
The solution involves configuring transmission power control using TPC commands contained in downlink control information at timings based on existing systems, shortened processing times, or synchronized with HARQ feedback and UL scheduling, allowing for proper power management even with shortened processing times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If shortened processing times are introduced to reduce latency, then latency is reduced and productivity increases, but transmission power control becomes difficult and reliability deteriorates
Solution Approach 1:
The patent applies preliminary action by determining transmission power in advance for uplink signals. The base station determines the transmission power of uplink signals in advance, and the user terminal transmits uplink signals according to this predetermined power level. This allows power control to be established before the actual transmission occurs, ensuring reliability even when processing times are shortened.
Solution Approach 2:
The patent implements dynamics by making the transmission power control adaptable to different signal types and conditions. The system dynamically adjusts whether to apply power control based on the specific uplink signal type (data or control signal) and the timing relationships between downlink and uplink transmissions. This dynamic approach ensures accurate power control while accommodating shortened processing times.
2Ease of operation
If 1-ms subframes are used as processing units, then existing LTE compatibility is maintained and ease of operation is preserved, but latency reduction capability is limited
Solution Approach 1:
The patent applies dynamics by enabling flexible timing configurations that can adapt between traditional 1-ms subframe operations and shortened processing time modes. The system dynamically adjusts timing parameters such as k_PUSCH and k_PUCCH based on whether shortened processing time is configured, allowing seamless transition between operational modes while maintaining LTE compatibility.
Solution Approach 2:
The patent implements parameter changes by modifying timing parameters (k_PUSCH, k_PUCCH) and power control application timings based on the configured processing time mode. When shortened processing time is enabled, the system changes these parameters to reflect the reduced timing, allowing the same 1-ms subframe structure to support both traditional and low-latency operations.
3Measurement precision
If transmission power control is applied to all uplink signals, then power management accuracy improves, but processing load on user terminals increases
Solution Approach 1:
The patent applies local quality by differentiating power control application based on the specific type of uplink signal. Control signals (such as HARQ-ACK, CSI, SR) are treated differently from data signals (PUSCH). The system applies power control selectively according to the local characteristics of each signal type, ensuring accurate power management for control signals while reducing processing requirements for data transmissions.
Solution Approach 2:
The patent implements partial action by applying power control only where necessary rather than uniformly to all uplink signals. The system determines whether power control should be applied based on the specific signal type and timing conditions, applying it partially to control signals while potentially omitting or simplifying it for data signals, thus reducing overall processing load while maintaining necessary power management accuracy.
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
The present invention is designed to control transmission power properly even when communication is controlled based on shortened processing time. A user terminal communicates in a cell where a shortened TTI, having a transmission time interval (TTI) length shorter than 1 ms, is used, and/or in a cell where communication is controlled based on shortened processing time, which is shorter than in existing LTE systems, and this user terminal has a receiving section that receives a DL signal, a transmission section that transmits a UL signal in response to the DL signal, and a control section that controls transmission power of the UL signal based on a power control command contained in downlink control information transmitted in a predetermined transmission time interval in which the DL signal is transmitted, or in a transmission time interval located before the predetermined transmission time interval.