Closed-Loop Uplink Antenna Selection for Non-Reciprocal Channels
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Solution Overview
Problem
Existing wireless communication systems face challenges in antenna selection due to the lack of reciprocity between downlink and uplink channels, leading to sub-optimal antenna configurations that result in signal degradation, increased recovery errors, and decreased data throughput.
Innovation Solution
Implementing closed-loop antenna selection (CLAS) where a network node selects uplink antenna configurations based on uplink reference signals, linked to specific precoding, to mitigate signal degradation and support a wider variety of user equipment (UEs).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If open-loop antenna selection is used, then device complexity is reduced, but signal quality deteriorates due to lack of reciprocity between downlink and uplink channels
Solution Approach 1:
The patent implements closed-loop antenna selection where the network node provides feedback to the UE about the selected antenna configuration. The network node determines the optimal antenna selection based on uplink reference signals and communicates this selection back to the UE, ensuring that the antenna configuration adapts to actual uplink channel conditions rather than relying on downlink channel reciprocity assumptions.
Solution Approach 2:
The network node performs the antenna selection determination itself based on received uplink reference signals, rather than relying on UE-based selection. This self-service approach allows the network node to directly optimize antenna configuration based on actual uplink channel measurements, improving signal quality while maintaining manageable complexity through centralized control.
2Reliability
If closed-loop antenna selection is implemented, then signal quality is enhanced, but control signaling overhead increases
Solution Approach 1:
The patent leverages existing uplink reference signals that serve multiple purposes: they are used for both channel estimation and antenna selection determination. By making the reference signals serve dual functions, the system avoids additional dedicated signaling for antenna selection, thereby reducing overhead while maintaining the benefits of closed-loop selection.
Solution Approach 2:
The antenna selection information is conveyed using existing uplink grant structures and DCI formats that are already part of the system. Rather than creating entirely new signaling mechanisms, the patent reuses and adapts existing control signaling frameworks to carry antenna selection information, minimizing additional overhead.
3Productivity
If antenna switching time delay is not considered, then productivity is improved through faster transmissions, but reliability decreases due to hardware settling time requirements
Solution Approach 1:
The network node determines the antenna selection in advance based on uplink reference signals received before the actual data transmission. This preliminary determination allows the selected antenna configuration to be prepared and settled before the transmission begins, ensuring hardware stability while maintaining efficient scheduling. The antenna selection is finalized before the uplink grant is issued, allowing adequate settling time.
Solution Approach 2:
The patent incorporates antenna switching time delay considerations into the scheduling and timing of uplink transmissions. By accounting for the hardware settling time in advance, the system ensures that antenna switching is completed and stabilized before data transmission begins, preventing signal instability while minimizing impact on throughput through proper timing coordination.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a network node may receive one or more uplink reference signals that are associated with a plurality of antennas at a user equipment (UE). The network node may transmit an indication of a network-node-based uplink antenna selection for the UE, the network-node-based uplink antenna selection being linked to specific precoding assigned to a future uplink transmission, the network-node-based uplink antenna selection being based at least in part on the one or more uplink reference signals. Numerous other aspects are described.