DM-RS Frequency Hopping and Port Aggregation for High-Band Demodulation
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Solution Overview
Problem
Existing mobile communication systems face challenges in efficiently managing demodulation reference signal (DM-RS) resources, particularly in high-frequency bands, leading to suboptimal channel estimation and data demodulation performance.
Innovation Solution
Implementing dynamic DM-RS resource allocation and enhancement techniques, including frequency shift/hopping, DM-RS antenna ports aggregation, and pattern determination, to improve DM-RS frequency density and coverage in slots, as well as enhancing PDCCH and PUCCH DM-RS based on subcarrier spacing and operating frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DM-RS resource allocation is increased to improve channel estimation accuracy, then measurement precision improves, but resource overhead increases
Solution Approach 1:
The patent implements dynamic DM-RS resource allocation where the density and positioning of DM-RS resources are adjusted based on channel conditions, mobility states, and service requirements. This allows the system to optimize channel estimation accuracy while adapting resource consumption to actual needs, avoiding static over-provisioning of DM-RS resources.
Solution Approach 2:
The patent applies different DM-RS density configurations to different time-frequency resources based on local channel characteristics. In regions with poor channel conditions or high mobility, higher DM-RS density is allocated, while in stable regions, lower density suffices. This localized optimization improves overall estimation accuracy without uniformly increasing resource overhead across the entire system.
2Reliability
If DM-RS frequency density is increased to improve demodulation performance, then reliability improves, but resource overhead increases
Solution Approach 1:
The system dynamically adjusts DM-RS frequency density based on instantaneous channel conditions, mobility indicators, and service QoS requirements. This enables the network to maintain high demodulation reliability when needed while reducing resource overhead during favorable conditions, achieving adaptive optimization of the reliability-overhead tradeoff.
Solution Approach 2:
The patent changes key parameters including DM-RS frequency density, time density, and resource element positioning based on operating conditions. By modifying these parameters dynamically, the system can optimize demodulation performance for different scenarios (e.g., high mobility vs. static, different frequency bands) without committing to a fixed high-overhead configuration.
3Measurement precision
If frequency shift and hopping of DM-RS are implemented to increase frequency density, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent implements periodic frequency hopping patterns for DM-RS where the frequency position follows predetermined periodic sequences. This periodic structure simplifies the processing complexity compared to arbitrary frequency shifts, as the WTRU can efficiently track and process DM-RS according to known periodic patterns while still achieving frequency domain diversity and improved estimation accuracy.
4Adaptability or versatility
If multiple types of REG with different DM-RS densities are used to adapt to different conditions, then adaptability improves, but device complexity increases
Solution Approach 1:
The system dynamically selects and switches between different REG types with varying DM-RS densities based on current operating conditions such as frequency band, subcarrier spacing, and channel quality. This dynamic adaptation allows the system to optimize performance for different scenarios while the network controls the complexity through centralized configuration rather than requiring complex local decision-making at the WTRU.
Data Source
AI summary
Systems, apparatus and methods are described for dynamic demodulation signal resource allocation. PDSCH/PUSCH DMRS enhancement is provided. A dynamic indication of reference signal functionality may be provided in a slot for an additional DM-RS. A configured CSI-RS/SRS may be dynamically indicated to use as an additional DM-RS in a slot. Frequency shift/hopping of DM-RS as a function of OFDM symbol and/or the order of OFDM symbol containing DM-RS may increase frequency density within a slot. DM-RS antenna port aggregation may increase DM-RS frequency density. One or more DM-RS antenna ports may be used to demodulate the same layer. PDCCH DMRS enhancement is provided. Frequency shift/hopping of PDCCH DMRS may be provided as a function of a REG index within an REG bundle, OFDM symbol index, etc. Use of multiple types of REG (e.g., low and high DM-RS) and REG type may be determined based on subcarrier spacing, operating frequency band, etc.