OFDMA Uplink Control Mapping Around DMRS for Reliable UCI
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Solution Overview
Problem
Current LTE systems face challenges in efficiently multiplexing uplink control information (UCI) with uplink shared channel data using OFDMA waveforms, as existing methods do not account for dynamic DMRS patterns and fail to preserve the performance benefits of SC-FDMA while accommodating symmetric uplink/downlink designs.
Innovation Solution
Novel RE mapping schemes are introduced for UCI and UL-SCH data within a PUSCH transmission based on UL OFDMA waveforms, allowing dynamic adaptation of UCI mapping according to DMRS patterns, UCI payload size, and frequency diversity gains, while maintaining spectral efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UCI is mapped to resource elements using conventional methods, then the mapping process is simple, but frequency diversity is not maximized and channel estimation performance is suboptimal
Solution Approach 1:
The patent applies local quality by differentiating the mapping strategy for different UCI types. ACK/NACK symbols are mapped to resource elements with highest frequency diversity gain, while CSI reports are mapped considering channel estimation performance. This localized optimization of mapping quality for different information types resolves the contradiction between simple mapping and optimized performance.
Solution Approach 2:
The patent implements dynamic mapping strategies where the resource element selection depends on the specific UCI type and channel conditions. The mapping is not fixed but adapts based on whether the UCI contains ACK/NACK information, CSI reports, or other control information, allowing the system to optimize performance dynamically while managing complexity through type-based differentiation.
2Reliability
If UCI symbols are mapped to maximize frequency diversity, then reliability is improved, but the mapping methodology becomes more complex
Solution Approach 1:
The patent segments the UCI mapping process into distinct procedures based on UCI type. Different mapping rules are applied for ACK/NACK UCI versus CSI report UCI. This segmentation allows complex frequency diversity optimization to be broken down into manageable, type-specific mapping procedures, reducing overall system complexity while maintaining high frequency diversity gain.
3Measurement precision
If UCI mapping considers channel estimation performance, then estimation accuracy improves, but mapping complexity increases
Solution Approach 1:
The patent applies local quality by tailoring the mapping strategy to the specific requirements of different UCI types. For CSI reports, mapping prioritizes proximity to reference signals for accurate channel estimation. For ACK/NACK, frequency diversity is prioritized. This localized optimization achieves high measurement precision for channel estimation without requiring complex unified mapping algorithms.
Data Source
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AI summary
Methods and apparatus are described for transmitting uplink control information (UCI) over an OFDMA-based uplink. In some embodiments, UCI symbols are mapped to resource elements (REs) in the time/frequency resource grid to maximise frequency diversity. In some embodiments, UCI is mapped in a manner that takes into account channel estimation performance by mapping UCI symbols to those REs that are closest (in terms of OFDM subcarriers/symbols) to REs that carry reference signals.