Uplink Spatial Relation Configuration via MAC-CE Signaling
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Solution Overview
Problem
Current wireless communication systems face inefficiencies in managing uplink reference signals, particularly in updating spatial relations for sounding reference signals, which affects beam management and communication quality due to outdated spatial configurations caused by UE movement.
Innovation Solution
A method and apparatus that determine a set of available spatial relations for transmitting sounding reference signals, with a medium-access-control control element indicating the appropriate spatial relation for transmission, allowing for efficient beam management and reliable communications by reducing latency and overhead in providing updated spatial relations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If spatial relations are updated periodically or through traditional procedures, then beam management maintains stability, but latency increases and communication efficiency deteriorates due to outdated spatial configurations caused by UE movement
Solution Approach 1:
The base station pre-configures multiple spatial relations (spatial relation info) for the UE before actual transmission is needed. When UE movement occurs, the base station can quickly indicate which pre-configured spatial relation to use without requiring time-consuming measurement and reporting procedures, thus reducing latency in spatial relation updates
Solution Approach 2:
The system dynamically selects spatial relations based on current channel conditions and UE movement. The base station can update spatial relation indications through MAC CE or DCI signaling, allowing the spatial configuration to adapt rapidly to changing conditions without fixed periodic updates, thereby improving both speed and reducing time loss
2Measurement precision
If multiple spatial relations are configured and managed, then beam management accuracy improves, but system complexity increases due to additional configuration and signaling overhead
Solution Approach 1:
The spatial relation configuration is segmented into multiple independent spatial relation info entries, each associated with different reference signals (SSB, CSI-RS, SRS). This allows the system to manage complexity by organizing spatial relations in structured groups while maintaining high accuracy through selective application of appropriate spatial relations for different transmission purposes
Solution Approach 2:
The same spatial relation configuration mechanism serves multiple functions: it supports different reference signal types (SSB, CSI-RS, SRS), different transmission purposes (beam management, channel sounding, uplink control), and different update triggers (MAC CE, DCI). This multi-functionality reduces overall system complexity by using a unified framework rather than separate mechanisms for each function
Data Source
AI summary
Methods, systems, and devices for wireless communications are described in which spatial relations for one or more uplink reference signal transmissions, such as sounding reference signal (SRS) transmissions, may be configured and a particular spatial relation indicated in a medium access control (MAC) control element (CE). A base station may configure a pool of available spatial relations for use in SRS transmissions, and the MAC-CE may indicate which spatial relation of the set of available spatial relations is to be used. In other cases, the MAC-CE may provide all of the spatial relation information for an associated SRS transmission. The UE, responsive to receiving the MAC-CE, may transmit a SRS to the base station using the indicated spatial relation.