Rank-2 CSI Construction via 1-Layer SRS
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Solution Overview
Problem
Current commercial UEs do not support transmitting SRS from 2 antennas or antenna switching, limiting the availability of dual-layer CSI in BS, which is crucial for achieving higher system throughput in MU-MIMO scenarios.
Innovation Solution
A base station (BS) method to construct a 2-layer channel matrix using a 1-layer SRS by identifying dominant directions and coefficients between antenna polarizations, enabling the transmission of downlink signals based on this constructed matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 2-layer CSI is obtained through 2-antenna SRS transmission or antenna switching, then system throughput is improved, but device complexity and UE capability requirements increase
Solution Approach 1:
The patent creates a virtual copy of the 2-antenna SRS transmission capability at the base station side through signal processing. By receiving only 1-layer SRS from the UE and applying matrix construction algorithms, the base station synthesizes equivalent 2-layer CSI information, effectively copying the functionality of 2-antenna transmission without requiring the UE to actually transmit from 2 antennas.
Solution Approach 2:
The patent introduces an intermediary processing layer at the base station that transforms 1-layer SRS into 2-layer CSI. The matrix construction algorithm acts as an intermediary mechanism, converting limited UE capabilities into enhanced system performance by processing the single-layer signal through mathematical transformations to extract multi-layer channel state information.
2Reliability
If dual-layer CSI is available at BS side, then MU-MIMO performance is improved, but current commercial UEs cannot provide it due to hardware limitations
Solution Approach 1:
The patent makes the base station capable of handling multiple UE types universally. The matrix construction algorithm allows the system to work with UEs that have limited 1-antenna SRS capability while achieving performance equivalent to 2-antenna UEs. This multi-functional approach enables the system to accommodate both simple 1-antenna UEs and potentially future 2-antenna UEs without requiring different processing paths.
Solution Approach 2:
The patent changes the parameter representation of channel state information from direct 2-antenna measurements to mathematically constructed 2-layer CSI from 1-antenna SRS. By transforming the way CSI is obtained and represented, the system achieves dual-layer performance with single-antenna hardware, effectively changing the parameter acquisition method while maintaining the desired performance level.
3Device complexity
If 1-layer SRS is received from UE, then device complexity is reduced, but dual-layer channel matrix construction becomes challenging
Solution Approach 1:
The patent performs preliminary organization of the 1-layer SRS signal at the base station, arranging it according to antenna polarizations before applying matrix construction algorithms. This preliminary preparation of the received signal structure simplifies the subsequent dual-layer matrix construction by pre-organizing the data in a format that facilitates the mathematical transformations needed to extract 2-layer CSI information.
Data Source
AI summary
A method of a base station (BS) in a wireless communication system is provided, The method comprises: receiving, from a user equipment (UE), a 1st layer sounding reference signal (SRS); arranging the 1st layer SRS based on two antenna polarizations of an antenna system of the BS; identifying a dominant direction of a channel based on the 1st layer SRS; identifying a coefficient between two antenna polarizations based on the 1st layer SRS; constructing a 2-layer channel matrix based on the identified dominant direction and the identified coefficient; and transmitting, to the UE, a downlink signal via the antenna system based on the constructed 2-layer channel matrix.