User Terminal DMRS and PUCCH Hopping for Short-TTI Interference
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Solution Overview
Problem
In future radio communication systems with shorter transmission time intervals (TTIs) than 1 ms, the challenge lies in appropriately configuring sequences for DMRS and PUCCH to manage inter-cell interference effectively.
Innovation Solution
A user terminal and radio communication method that determine the index of a predetermined sequence for DMRS and PUCCH based on symbol and frequency resource indices, employing hopping patterns and cyclic shifts to randomize sequences across symbols and frequency resources, reducing inter-cell interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a TTI shorter than 1 ms is introduced for future radio communication systems, then transmission speed and latency are improved, but inter-cell interference management becomes more difficult due to shorter sequence hopping periods
Solution Approach 1:
The patent applies dynamics by making the sequence hopping pattern configurable and adaptable to different TTI lengths. The base station can dynamically select and notify the terminal of appropriate hopping patterns (first pattern for normal TTI, second pattern for short TTI) based on the actual transmission time interval being used, allowing the system to optimize sequence hopping behavior for each TTI duration to manage interference effectively.
Solution Approach 2:
The patent changes parameters by introducing different sequence hopping patterns specifically tailored for different TTI lengths. When short TTI is configured, a second hopping pattern with adjusted hopping period and sequence generation parameters is applied, whereas normal TTI uses a first hopping pattern. This parameter adaptation allows effective interference management despite the shorter transmission time interval.
2Object-affected harmful factors
If sequence hopping is applied per slot in existing LTE systems, then inter-cell interference is reduced, but the sequence configuration becomes inappropriate for shorter TTI durations
Solution Approach 1:
The patent makes the sequence hopping configuration dynamic by providing different hopping patterns for different TTI durations. The base station determines the appropriate hopping pattern based on the configured TTI length and notifies the terminal accordingly, allowing the sequence configuration to adapt to varying time interval requirements rather than using a fixed per-slot hopping approach.
Solution Approach 2:
The patent changes the hopping pattern parameters based on TTI configuration. For normal TTI, a first hopping pattern is used, while for short TTI, a second hopping pattern with modified parameters (such as hopping period and sequence generation rules) is applied. This parameter change ensures that sequence hopping remains effective for interference reduction while being appropriate for the specific TTI duration being used.
3Productivity
If DMRS and PUCCH sequences are configured for short TTI, then communication efficiency is improved, but inter-cell interference increases without proper sequence randomization
Solution Approach 1:
The patent applies dynamics by configuring different sequence hopping patterns for short TTI compared to normal TTI. The base station determines and notifies the terminal of the appropriate second hopping pattern when short TTI is configured, enabling effective sequence randomization and interference management specifically tailored for the shorter transmission time interval while maintaining communication efficiency.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
To appropriately configure a sequence to be applied to a DMRS and/or a PUCCH in future radio communication systems, one aspect of a user terminal of the present invention includes a transmitting section that transmits a demodulation reference signal and/or an uplink control channel, and a control section that controls a predetermined sequence to be applied to the demodulation reference signal and/or the uplink control channel, based on at least a symbol index and/or a frequency resource index.