Uplink SRS Precoding for Better Cell-Edge Sounding Quality
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Solution Overview
Problem
Existing wireless communication systems, particularly in NR and LTE, face challenges in improving the sounding quality of uplink SRS transmissions, especially for cell-edge UEs with asymmetrical transmit and receive chains, leading to poor sounding quality.
Innovation Solution
Implementing precoders for uplink SRS transmissions, where the base station provides UE with precoders associated with configured SRS resources, allowing the UE to apply these precoders for improved sounding quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If UE transmits SRS without precoding, then device complexity is reduced, but sounding quality deteriorates for cell-edge UEs with asymmetrical transmit and receive chains
Solution Approach 1:
The base station provides precoder information to the UE in advance before the UE transmits the SRS. This preliminary provision of precoding parameters enables the UE to apply appropriate precoding to improve sounding quality without requiring complex real-time precoder selection or calculation capabilities at the UE side.
Solution Approach 2:
The base station acts as an intermediary by determining and providing the precoder information to the UE. This mediates the asymmetrical capability between UE transmit and receive chains, allowing the UE to achieve improved sounding quality through base station-assisted precoding without requiring equal transmit and receive chain capabilities at the UE.
2Measurement precision
If UE applies precoders for SRS transmission, then sounding quality is improved, but device complexity increases
Solution Approach 1:
The base station provides precoder information to the UE in advance before the UE transmits the SRS. This preliminary provision of precoding parameters enables the UE to apply appropriate precoding to improve sounding quality without requiring complex real-time precoder selection or calculation capabilities at the UE side.
Solution Approach 2:
The UE applies the precoder information provided by the base station to its own SRS transmission. This self-service approach allows the UE to improve its own sounding quality using externally provided parameters without requiring complex inter-device coordination or additional network infrastructure.
3Reliability
If base station provides precoder information to UE, then communication reliability is improved, but network overhead increases
Solution Approach 1:
The provided precoder information serves multiple functions: it improves SRS sounding quality for channel estimation and also enhances uplink data transmission reliability. This multi-functionality justifies the network overhead by providing dual benefits from the same information exchange.
Solution Approach 2:
The base station provides precoder parameters that change according to channel conditions, UE capability, and transmission requirements. By dynamically adjusting these parameters based on system state, the network optimizes the balance between communication reliability and overhead efficiency.
Data Source
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AI summary
Certain aspects of the present disclosure provide techniques for uplink sounding reference signal (SRS) transmission with precoding. A method for wireless communication by a user equipment (UE) includes receiving a SRS configuration that configures one or more SRS resource sets, each resource set including one or more SRS resources, each SRS resource comprising one or more SRS ports. The UE receives a set of precoders via an indicator, the set of precoders including a precoder associated with each SRS resource and determines one or more precoders to apply for one or more SRS transmissions via one or more of the SRS resources.