Additional DMRS Mapping Control for Doppler Correction
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Solution Overview
Problem
Current radio communication systems lack effective methods for controlling additional DMRS mapping in second or later slots during time direction bundling, which hinders doppler fluctuation correction.
Innovation Solution
A user terminal with a reception section, control section, and channel estimation section that separates and maps additional DMRS based on channel quality, allowing for controlled doppler fluctuation correction by selecting the presence or absence and position of additional DMRS mapping according to specific rules in second or later slots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional DMRS is mapped in every slot for time direction bundling, then doppler fluctuation correction is improved, but overhead increases
Solution Approach 1:
The patent applies local quality by mapping additional DMRS selectively based on local channel conditions. Specifically, additional DMRS is mapped only in slots where the channel quality indicator (CQI) falls below a predetermined threshold, rather than uniformly across all slots. This localized approach ensures doppler fluctuation correction is applied precisely where needed, improving reliability while reducing overall overhead.
Solution Approach 2:
The patent implements dynamics by making the additional DMRS mapping adaptive to changing channel conditions. The mapping decision is dynamically adjusted based on real-time CQI measurements from each slot. When channel conditions deteriorate (low CQI), additional DMRS is mapped to correct doppler fluctuations; when conditions are good, mapping is reduced. This dynamic adaptation resolves the contradiction between maintaining correction effectiveness and minimizing overhead.
2Device complexity
If additional DMRS mapping position is fixed in second or later slots, then device complexity is reduced, but adaptability to channel quality changes deteriorates
Solution Approach 1:
The patent resolves this contradiction by making the additional DMRS mapping dynamic and adaptive to channel conditions. Instead of using a fixed mapping position regardless of channel quality, the system dynamically determines whether to map additional DMRS in each slot based on CQI thresholds. This dynamic approach increases adaptability to channel quality changes while maintaining relatively simple device complexity through rule-based decision logic.
Data Source
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AI summary
Provided is a user terminal which is used in a future wireless communication system which bundles a plurality of slots (sub-frames) in the time direction. When applying bundling, in the leading slot, Additional DMRS (Demodulation Reference Signal) is mapped according to channel quality (factors which lead to a deterioration in quality, such as Doppler shift, propagation environment, etc.), and in second and subsequent slots, the existence of Additional DMRS mapping or the mapping position is selected on the basis of rules concerning Additional DMRS mapping. The control unit (203) of the user terminal (20) specifies, in second and subsequent slots, the existence of Additional DMRS mapping and the mapping position on the basis of the aforementioned rules.