Multi-Antenna Reference Signal Distribution for Channel Estimation
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Solution Overview
Problem
In multi-antenna wireless communication systems, existing methods face challenges in efficiently transmitting reference signals for channel measurement, particularly when using a large number of antennas, as they struggle to effectively distribute channel information across multiple ports, leading to increased feedback overhead and potential inaccuracies in channel estimation.
Innovation Solution
The method involves setting a subset of antenna ports as cell-specific reference signal (CRS) ports and demodulation reference signal (DM-RS) ports, allowing for the transmission of CRSs and DM-RSs across multiple horizontal and vertical domains, with feedback on channel measurement information received from user equipment (UE), and applying precoding based on this information to optimize channel estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large number of antennas are used for multi-antenna transmission, then transmission capacity and beamforming performance are improved, but feedback overhead and channel estimation complexity increase
Solution Approach 1:
The patent segments the channel measurement process by introducing two types of reference signals: CRS for wideband channel measurement and DM-RS for subband channel measurement. This segmentation allows the system to obtain channel information at different granularities, reducing the amount of feedback required while maintaining accurate channel estimation for beamforming operations.
Solution Approach 2:
The patent introduces a new dimension of measurement granularity by operating at both wideband and subband levels. Instead of a single measurement approach, the system performs measurements across frequency dimensions (wideband) and within specific frequency subsets (subband), enabling more efficient feedback of channel state information.
2Measurement precision
If channel measurement is performed across all antenna ports, then channel estimation accuracy is improved, but feedback overhead increases
Solution Approach 1:
The patent applies partial measurement action by using DM-RS for subband measurement only where needed for precise beamforming, while using CRS for broader wideband coverage. This partial approach to measurement at different frequency granularities achieves necessary accuracy without the excessive overhead of measuring all antenna ports at all frequency levels.
3Loss of information
If reference signals are transmitted on all antenna ports, then channel information distribution is improved, but system complexity and overhead increase
Solution Approach 1:
The patent makes reference signals universal by designing CRS and DM-RS to serve multiple functions: CRS provides wideband channel measurement for overall channel characterization, while DM-RS provides subband measurement for precise beamforming. This multi-functionality allows a single reference signal framework to address both broad channel information distribution and specific beamforming requirements.
Data Source
AI summary
The present invention relates to a method and an apparatus for transmitting, by a base station, a reference signal in a wireless communication system supporting a multi-antenna consisting of a plurality of horizontal domain antennas and a plurality of vertical domain antennas. Specifically, the method comprises the steps of: configuring, as a cell-specific reference signal (CRS) port, M first antenna ports among a total of N antennas that the base station has (where N and M are positive integers, N>M); transmitting a CRS using the M first antenna ports and transmitting a demodulation reference signal (DM-RS) using O second antenna ports (where O is a positive integer, N>O), to a terminal; and receiving channel measurement information using the CRS and the DM-RS which is fed back from the terminal.