Secondary-Cell PUCCH Beam Selection Without Spatial Relation Data
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Solution Overview
Problem
User Equipment (UE) faces challenges in efficiently selecting an uplink transmission beam for a secondary cell (SCell) when the base station is in a being-activated state, particularly due to the absence of an uplink spatial relation configuration and beam correspondence support.
Innovation Solution
The UE determines the availability of uplink spatial relation configuration and beam correspondence, and based on these determinations, selects an appropriate uplink transmission beam from multiple beams for PUCCH transmission to the SCell, enabling the SCell to transition from a being-activated state to an activated state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the UE uses a random or default uplink transmission beam for PUCCH transmission to the SCell, then the activation process can proceed without requiring precise beam configuration, but the communication reliability and activation success rate deteriorate due to suboptimal beam selection
Solution Approach 1:
The network performs downlink beam sweeping and SSB transmission before the SCell activation, allowing the UE to measure and identify the optimal downlink beam in advance. This preliminary beam identification enables the UE to select the corresponding uplink transmission beam when activating the SCell, avoiding random beam selection while maintaining operational simplicity.
Solution Approach 2:
The UE provides feedback to the network about the measured downlink beam quality (e.g., RSRP measurements of SSBs). Based on this feedback, the network can confirm or adjust the beam selection for SCell activation, creating a closed-loop system that improves activation success rate while keeping the UE's operation simple.
2Measurement precision
If the UE waits for uplink spatial relation configuration from the network before selecting an uplink transmission beam, then beam selection accuracy improves, but the activation time and process complexity worsen
Solution Approach 1:
The network transmits downlink reference signals (SSBs) and performs beam sweeping before the SCell activation command, allowing the UE to measure and identify the best beam in advance. This preliminary measurement eliminates the need for time-consuming beam configuration during activation, reducing activation time while maintaining high beam selection accuracy.
Solution Approach 2:
The UE autonomously selects the uplink transmission beam based on its own measurements of downlink SSBs and beam correspondence principles, without waiting for explicit network configuration. This self-service approach eliminates configuration delays while achieving accurate beam selection through the UE's own measurement capabilities.
3Device complexity
If the UE supports beam correspondence and uses downlink beam information to determine uplink transmission beam, then the number of required configurations and measurements reduces, but this capability cannot be utilized by UEs that do not support beam correspondence
Solution Approach 1:
The network configures multiple downlink SSBs with different spatial parameters and transmits them via beam sweeping. The UE measures these SSBs and selects the best beam based on its capabilities (beam correspondence or not). This parameter variation approach allows the same mechanism to serve both UE types, reducing configuration complexity while maintaining broad compatibility.
Solution Approach 2:
The downlink SSB transmission mechanism serves dual purposes: it provides reference signals for channel measurement and simultaneously enables beam identification for both beam-correspondence-capable and non-capable UEs. This universal approach allows a single configuration mechanism to support different UE types, reducing overall system complexity while maintaining versatility.
Data Source
AI summary
A user equipment (UE) is provided to select an uplink transmission beam to communicate with a base station in a secondary cell of a carrier aggregation (CA) scheme. The UE can communicate with a first base station in a primary cell (PCell), and receive a command from the wireless network to activate a physical uplink control channel (PUCCH) transmission to a second base station in a secondary cell (SCell). The second base station can be in a being-activated state. The UE can determine whether an uplink spatial relation configuration is provided to the UE, and determine whether the UE supports beam correspondence. Based on the determinations, the UE can select an uplink transmission beam for the PUCCH transmission to the second base station.