Uplink Precoder Determination via Downlink Reference Signal Quasi-Co-Location
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Solution Overview
Problem
In wireless communication systems, especially in 5G and NR, the estimation accuracy of UE-specific reference signals for channel properties is inadequate, leading to undesirable link and system performance degradation due to geographical separation of antenna ports and differing statistical properties, and there is a need to reduce uplink interference caused by simultaneous transmissions from multiple UEs.
Innovation Solution
A method where a wireless device determines an uplink precoder based on channel measurements from first and second downlink reference signal resources, enabling a transmission on an uplink reference signal resource that is quasi co-located with the first but not the second, to suppress interference and improve channel estimation quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If UE-specific reference signals are used for channel estimation, then transmission transparency is achieved, but estimation accuracy deteriorates due to geographical separation of antenna ports
Solution Approach 1:
The patent segments the reference signal resources into multiple downlink reference signal resources (first and second resources) with different quasi-co-location relationships. The UE performs separate channel estimations for each resource type, allowing accurate channel estimation for each transmission path while maintaining transmission transparency. This segmentation enables the UE to handle multiple antenna ports independently with appropriate estimation methods for each.
2Productivity
If multiple transmission points transmit control signaling simultaneously, then network flexibility and data rate are improved, but interference increases
Solution Approach 1:
The patent applies local quality by establishing different quasi-co-location relationships for different downlink reference signal resources. The first downlink reference signal resource is configured with quasi-co-location to the uplink reference signal resource, while the second is not. This allows the UE to apply appropriate channel estimation quality assumptions locally to each resource, enabling simultaneous transmissions from multiple points while managing interference through differentiated resource configurations.
3Productivity
If UEs transmit uplink data simultaneously to multiple base stations, then system capacity increases, but uplink interference to other base stations increases
Solution Approach 1:
The patent implements preliminary action by configuring the UE with knowledge of quasi-co-location relationships before uplink transmission. The network provides indication information about which downlink reference signal resources are quasi-co-located with uplink resources. This allows the UE to pre-determine appropriate precoding and transmission parameters that minimize interference to non-serving base stations while maximizing system capacity through simultaneous transmissions.
Data Source
AI summary
Systems and method of reducing interference in a wireless communication system are provided. In one exemplary embodiment, a method by a wireless device (105, 200, 300a, 300b, 500, 1105, 1205, 1207) comprises determining (409, 909) an uplink precoder (107) based on channel measurements on first and second downlink reference signal resources. Further, the precoder enables a transmission (113) on an uplink reference signal resource that is precoded with the uplink precoder and that is quasi co-located (QCL) (121) with a transmission (111) on the first downlink reference signal resource but not QCL (123) with a transmission (115) on the second downlink reference signal resource.