Uplink Precoder Selection Using Downlink DMRS Measurements
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Solution Overview
Problem
There is a need for improved precoder selection methods in 5G NR communication systems to enhance uplink performance, particularly for reduced capability devices, which face challenges in maximizing resource utilization and power efficiency.
Innovation Solution
The method involves using downlink reference signals, specifically demodulation reference signals (DMRS), to measure and select uplink precoders, enabling more efficient uplink channel transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If codebook-based precoder selection is used, then uplink transmission reliability is improved, but device complexity and power consumption increase for reduced capability devices
Solution Approach 1:
The patent extracts the essential function of precoder selection from the complex codebook-based framework and implements it through a simplified measurement-based approach. The UE measures downlink channel quality using DMRS and selects precoders based on these measurements, eliminating the need for complex codebook management and feedback while maintaining transmission reliability.
Solution Approach 2:
The system enables the UE to autonomously select uplink precoders by measuring downlink channel conditions and applying reciprocity principles. This self-service mechanism eliminates the need for network-controlled precoder selection, reducing signaling overhead and device complexity while maintaining reliable uplink transmission.
2Measurement precision
If more reference signals are used for channel measurement, then measurement precision is improved, but resource utilization deteriorates
Solution Approach 1:
The patent makes the downlink DMRS serve multiple functions: it acts as both a demodulation reference signal for data reception and a channel measurement reference signal for uplink precoder selection. This multi-functionality eliminates the need for separate uplink sounding reference signals, improving resource utilization while maintaining measurement precision through the existing DMRS infrastructure.
3Use of energy by moving object
If uplink precoder selection is optimized for reduced capability devices, then power efficiency is improved, but uplink performance may deteriorate
Solution Approach 1:
The patent changes the operational parameters of reduced capability devices by enabling dynamic precoder selection based on downlink channel measurements. This allows the devices to adapt their transmission parameters to current channel conditions, improving power efficiency by avoiding unnecessary high-power transmissions while maintaining uplink performance through measurement-guided precoder optimization.
Data Source
AI summary
An apparatus, e.g., a UE, for selecting an uplink precoder using a non-codebook-based procedure is disclosed. The UE may receive, from a base station (BS), at least one downlink reference signal comprising at least one DMRS via at least one downlink channel. The UE may measure, based on the at least one downlink reference signal, the at least one downlink channel. The measuring may be based at least in part on the at least one DMRS. The UE may select at least one first uplink precoder for at least one uplink channel corresponding to the at least one downlink channel based on the measuring of the at least one downlink channel. The UE may transmit, to the BS, at least one uplink reference signal based on the at least one first uplink precoder for the at least one uplink channel.