Multi-port Reference Signals for Beam Pair Selection
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Solution Overview
Problem
Current beam management techniques in wireless communications, particularly in MIMO mode, often select beam pairs based on signal strength measurements from synchronization signal blocks (SSBs), which may not optimize spectral efficiency for rank-2 transmissions, leading to suboptimal performance in terms of achievable rate.
Innovation Solution
The use of multi-port reference signals, such as two-port CSI-RS, allows user equipment (UE) to determine spectral efficiency estimates based on signal strength and phase information, enabling the selection of beam pairs that maximize spectral efficiency for communications with the base station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If beam pairs are selected based on signal strength measurements from SSBs, then signal strength is maximized, but spectral efficiency for MIMO transmissions is not optimized
Solution Approach 1:
The patent changes the measurement parameter from signal strength (RSRP) to spectral efficiency estimates. The UE calculates spectral efficiency based on channel quality indicators (CQI) and rank indicators (RI) obtained from multi-port reference signals, thereby selecting beam pairs that optimize spectral efficiency rather than merely signal strength for MIMO transmissions
Solution Approach 2:
The patent introduces multi-port reference signals (specifically two-port CSI-RS) as an intermediary measurement signal. These reference signals enable the UE to obtain channel quality information and phase information necessary for calculating spectral efficiency estimates, serving as a mediator between the transmitted signal and the beam selection decision
2Ease of operation
If SSB measurements are used for beam management, then beam pair selection is simplified, but achievable rate for rank-2 transmissions is suboptimal
Solution Approach 1:
The patent changes the optimization criterion from signal strength to spectral efficiency estimates. By using CQI and RI values derived from multi-port reference signals, the system selects beam pairs that maximize achievable rate for MIMO transmissions while maintaining a relatively simple measurement and reporting process
Solution Approach 2:
The patent implements feedback mechanisms where the UE reports CQI and RI values to the base station based on measurements of multi-port reference signals. This feedback enables the base station to determine appropriate beam pairs and transmission parameters that optimize achievable rate for rank-2 MIMO transmissions
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. In some examples, a base station and a user equipment (UE) may utilize multi-port reference signals to determine a beam pair for rank-2 transmissions. For example, a UE may receive a set of multi-port reference signals, where each multi-port reference signal of the set corresponds to a unique beam pair and is received via two ports associated with two different polarizations. The UE may determine a spectral efficiency estimation for each multi-port reference signal of the set, select a beam pair associated with a multi-port reference signal with the highest determined spectral efficiency estimation of the set, and transmit an indication of the selected beam pair to the base station. Therefore, the UE and the base station may communicate using a beam pair which maximizes the spectral efficiency and rate of rank-2 transmissions.