Wireless Beamforming with SRS Switching for Channel Accuracy
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Solution Overview
Problem
Existing wireless communication systems face inaccuracies in downlink beamforming due to differences between uplink and downlink channels, leading to suboptimal performance, particularly when channel reciprocity is assumed but not fully met.
Innovation Solution
A method involving antenna and beam selection techniques, such as SRS switching, CSI-RS estimation, and PMI determination, is employed to optimize downlink beamforming by adaptively transmitting SRS switching signals and PMIs, leveraging techniques like antenna selection, beam selection, and reinforcement learning to enhance channel estimation and beamforming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If channel reciprocity is assumed for downlink beamforming, then device complexity is reduced, but measurement precision of downlink channel information deteriorates
Solution Approach 1:
The terminal performs uplink channel measurement in advance and feeds back SRS switching signals containing antenna subset information before downlink beamforming is executed. This preliminary action allows the base station to obtain more accurate downlink channel information through reciprocity while maintaining system complexity at acceptable levels.
Solution Approach 2:
The SRS switching signal acts as an intermediary that carries antenna subset information from the terminal to the base station. This intermediary enables the base station to select appropriate antennas for downlink beamforming based on uplink channel characteristics, improving measurement precision without requiring direct downlink channel measurement.
2Measurement precision
If antenna selection is performed to improve channel estimation accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The antenna array is segmented into multiple antenna subsets, each with different characteristics. The terminal evaluates multiple antenna subsets and selects the most appropriate one for SRS transmission, enabling fine-grained optimization of channel estimation accuracy without requiring full-array complexity.
Solution Approach 2:
Instead of using all antennas for SRS transmission, the terminal transmits SRS signals through selected antenna subsets. This partial action reduces the complexity of channel estimation while maintaining or improving accuracy by focusing resources on the most relevant antennas for downlink beamforming.
Data Source
AI summary
A method of operating a wireless communication device including a plurality of antennas according to an exemplary embodiment of the present disclosure includes determining an antenna subset including at least one of the plurality of antennas, transmitting a sounding reference signal (SRS) switching signal to a base station through at least one antenna of the antenna subset, receiving a channel state information-reference signal (CSI-RS) transmitted using a first beam from the base station, selecting a precoding matrix indicator (PMI) based on the CSI-RS, transmitting the selected PMI to the base station, and receiving a signal transmitted from the base station through a second beam determined based on the SRS switching signal and the PMI.