SRS Antenna Switching for Asymmetric UE UL MIMO
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing asymmetric transmit/receive paths in user equipment (UE) configurations, particularly with advanced antenna setups like 1TX/4RX or 2TX/4RX, leading to complications in SRS antenna switching and uplink channel estimation for DL MIMO precoding.
Innovation Solution
The UE reports its transmit/receive capabilities and antenna switching capabilities to the base station, allowing for closed-loop or open-loop configurations of SRS transmissions, enabling efficient SRS configurations for UL MIMO, carrier aggregation, and aperiodic SRS transmissions based on UE capability and trigger messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SRS antenna switching is implemented to compensate for asymmetric transmit/receive paths, then uplink channel estimation accuracy for DL MIMO precoding is improved, but the complexity of SRS transmission configuration increases significantly
Solution Approach 1:
The patent implements dynamic SRS antenna switching where the UE alternates between different transmit antennas for SRS transmissions in different uplink slots. The base station configures multiple SRS resources associated with different antennas, and the UE dynamically selects which antenna to use based on the current slot, enabling accurate channel estimation for all receive antennas while maintaining manageable configuration complexity through structured resource association.
Solution Approach 2:
The patent segments the SRS transmission configuration into multiple independent SRS resources, each associated with a specific transmit antenna. This segmentation allows the base station to configure separate resources for each antenna without creating a combinatorial explosion of configuration parameters, thereby reducing overall configuration complexity while still enabling comprehensive channel estimation across all antennas.
2Adaptability or versatility
If multiple transmit antennas are configured for SRS transmission to support advanced antenna setups, then the capability to support higher data rates and advanced MIMO configurations is improved, but the complexity of antenna switching mechanisms increases
Solution Approach 1:
The patent creates a universal SRS resource configuration framework where a single set of configured SRS resources can serve multiple transmit antennas through time-division multiplexing. The same SRS resource configuration can be associated with different antennas at different times, allowing the system to support various antenna configurations (1TX/4RX, 2TX/4RX, etc.) without requiring separate dedicated configurations for each antenna combination, thus reducing overall system complexity.
3Productivity
If closed-loop SRS configuration is used to optimize SRS transmissions, then SRS transmission efficiency is improved, but the signaling overhead between UE and base station increases
Solution Approach 1:
The patent implements closed-loop configuration where the base station pre-configures multiple SRS resources and their associations with different transmit antennas before the UE begins SRS transmissions. This preliminary configuration allows the UE to efficiently switch between antennas without requiring real-time signaling for each switch, thereby optimizing SRS transmission efficiency while limiting signaling overhead to the initial configuration phase rather than continuous signaling.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE) may transmit a UE capability message, the UE capability message indicating a supported transmit antenna switching (TxAS) capability for each port of the UE. The UE may receive a configuration message indicating an uplink multiple-input/multiple-output (UL MIMO) configuration for the UE, the UL MIMO configuration being based at least in part on the UE capability message. The UE may identify, based at least in part on the configuration message, a sounding reference signal (SRS) configuration to use for transmitting SRSs in conjunction with the UL MIMO communications, the SRS configuration comprising a configuration for transmission by the UE of SRSs using at least one of the two or more ports of the UE, the SRSs transmitted on one or more antennas of the UE selected according to a TxAS configuration for the respective port.