Uplink Channel Quality Estimation via Downlink Beamformer Correlation
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Solution Overview
Problem
In 5G radio networks with analogue receivers, only a single beamformer can be evaluated at a time, making it challenging to change beamformers for user equipment (UE) without valid measurements for the new beamformer, as existing methods lack estimates for uplink transmission parameters when switching between different beamformers.
Innovation Solution
A method that involves receiving measurement reports from user equipment based on measurements from both a first and second downlink reference signal using different beamformers, allowing the network node to estimate the channel quality of an uplink channel and determine transmission parameters for a future uplink channel using a second beamformer by correlating the measurements from the first uplink channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only a single beamformer can be evaluated at a time in analogue receivers, then device complexity is reduced, but the ability to change beamformers for user equipment without valid measurements deteriorates
Solution Approach 1:
The network node performs preliminary actions by transmitting downlink reference signals using multiple different beamformers before uplink transmission parameter determination. This allows the UE to measure and report channel quality for multiple beamformers in advance, so when beamformer switching is needed, valid measurement data already exists for the new beamformer, eliminating the limitation of single beamformer evaluation.
2Measurement precision
If measurements are made on multiple downlink reference signals using different beamformers, then channel quality estimation for uplink transmission improves, but measurement and processing time increases
Solution Approach 1:
The network node transmits downlink reference signals using multiple different beamformers in advance of uplink transmission parameter determination. This preliminary measurement phase allows the UE to accumulate channel quality data for multiple beamformers beforehand, so that when beamformer switching occurs, the channel quality estimate is already available, avoiding time-consuming measurements at the moment of switching.
Solution Approach 2:
The network node continuously transmits downlink reference signals using different beamformers, maintaining an ongoing stream of measurement opportunities. This continuous action ensures that measurement data is always available and up-to-date, eliminating gaps where no valid measurements exist, while distributing the measurement load over time rather than concentrating it in single intensive bursts.
Data Source
AI summary
A method of estimating a channel quality of an uplink channel from a user equipment comprises receiving a measurement report from a user equipment, wherein the measurement report is based on at least one measurement made by the user equipment on a first downlink reference signal previously transmitted to the user equipment using a first downlink beamformer and at least one measurement made by the user equipment on a second downlink reference signal previously transmitted to the user equipment using a second downlink beamformer. The method comprises acquiring an estimate of a channel quality of a first uplink channel from the user equipment, in which a first uplink beamformer has been used to transmit a first uplink signal on the first uplink channel. The method comprises determining at least one transmission parameter for a future second uplink channel from the user equipment, in which a second uplink beamformer is to be used to transmit on the second uplink channel, wherein the at least one transmission parameter is determined based on the received measurement report and the acquired estimate of the channel quality of the first uplink channel.