Measurement Pilot Selection for Lower CSI-RS Feedback Overhead
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Solution Overview
Problem
The existing massive MIMO systems face high CSI-RS overheads and uplink feedback overheads due to the large number of antenna ports and resource blocks, which hinder efficient channel matrix estimation and precoding.
Innovation Solution
A method involving frequency-domain and space-domain dimension reduction of measurement pilots by selecting specific frequency domain units and precoding, allowing terminals to directly feed back feedback information without channel estimation or compression, reducing the overheads for channel matrix estimation and feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the quantity of ports and resource blocks increases to implement RB-level precoding with higher spectral efficiency, then spectral efficiency is improved, but CSI-RS overheads and uplink feedback overheads increase significantly
Solution Approach 1:
The patent segments the frequency domain by selecting only specific frequency domain units (e.g., every second RB) for measurement pilot transmission, rather than using all frequency domain units. This segmentation reduces the number of CSI-RS and feedback overheads while maintaining channel matrix estimation accuracy through the selected representative units.
Solution Approach 2:
The patent extracts only the essential information needed for channel matrix estimation by transmitting measurement pilots only in selected frequency domain units and having the terminal feed back only the necessary feedback information from these units, rather than processing all frequency domain units. This extraction reduces overheads while preserving the core functionality.
2Measurement precision
If measurement pilots are transmitted in all frequency domain units to ensure accurate channel matrix estimation, then estimation accuracy is improved, but time-frequency resource overheads increase
Solution Approach 1:
The patent applies partial action by transmitting measurement pilots only in selected frequency domain units rather than all units. The terminal uses channel information samples from these partial units to estimate the downlink channel matrix, achieving sufficient accuracy without the full overhead cost of processing all frequency domain units.
Data Source
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AI summary
This application relates to the field of communication technologies, and provides a signal sending method and apparatus. In the method, an access network device obtains a channel information sample, determines M' frequency domain units in M frequency domain units in an (x+T)th time unit based on the channel information sample, and sends one or more measurement pilots to a terminal in the M' frequency domain units. The measurement pilots are used to measure CSI, and the channel information sample includes channel information in an xth time unit to an (x+T-1)th time unit, where M'<M. In the method, the access network device may determine the M' frequency domain units in the M frequency domain units in the (x+T)th time unit to send the measurement pilots, to implement frequency-domain dimension reduction of the measurement pilots. Compared with a conventional technology in which one or more measurement pilots are sent in M frequency domain units, the method can reduce a quantity of frequency domain units for sending the measurement pilots, and reduce overheads for sending the measurement pilots, so that measurement pilot overheads for estimating a downlink channel matrix are reduced.