Sidelink PRS Resource Patterning With CBR-Based Slot Allocation
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Solution Overview
Problem
The standardization of sidelink (SL) positioning in 3GPP Release 18 requires defining a slot structure for transmitting positioning reference signals (PRS), which was not considered in earlier releases, and existing methods do not support the required accuracy for SL positioning.
Innovation Solution
A method for allocating time and frequency resources in a dedicated resource pool for SL-PRS transmission, including channel busy ratio (CBR) measurement and determining transmission parameters based on CBR, using a UE with a processor and non-transitory computer readable storage medium to manage SL-PRS allocation and CBR measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated resource pool is configured for SL-PRS transmission, then SL positioning accuracy is improved, but resource allocation complexity increases
Solution Approach 1:
The resource pool is segmented into specific slots and symbols dedicated for SL-PRS transmission. The network configures a resource pool indicator that identifies specific time-frequency resources within the SL resource pool, dividing the overall resource space into manageable segments for positioning operations.
Solution Approach 2:
The resource allocation is made dynamic through CBR-based adaptation. The UE measures the channel busy ratio in the dedicated resource pool and adjusts transmission parameters such as power control and resource selection based on the measured CBR, allowing the system to adapt to changing channel conditions while maintaining positioning accuracy.
2Productivity
If CBR measurement is performed in dedicated resource pool, then channel utilization is optimized, but measurement and control complexity increases
Solution Approach 1:
The UE autonomously performs CBR measurements in the dedicated resource pool and self-adjusts its transmission parameters based on the measured values. The UE independently determines whether to transmit SL-PRS in a slot based on CBR thresholds, eliminating the need for network-controlled adjustments and simplifying overall system complexity.
Solution Approach 2:
A feedback mechanism is established where the UE continuously measures CBR in the dedicated resource pool and uses this feedback to adjust transmission parameters. The measured CBR values are fed back into the transmission decision process, creating a closed-loop system that optimizes channel utilization while maintaining manageable complexity through standardized measurement procedures.
3Reliability
If transmission parameters are adjusted based on CBR, then positioning reliability is improved, but processing complexity increases
Solution Approach 1:
Transmission parameters such as power control and resource selection are dynamically changed based on CBR measurements. The UE adjusts transmission power and selects appropriate time-frequency resources according to the measured channel busy ratio, ensuring reliable positioning transmission under varying channel conditions while using standardized parameter adjustment rules.
Data Source
AI summary
A method and a device are provided in which a user equipment (UE) allocates, in a dedicated resource pool for transmitting a sidelink (SL)-positioning reference signal (PRS), a first resource in a slot for SL-PRS symbols, allocates, in the dedicated resource pool, a second resource in a control region of the slot for physical SL control channel (PSCCH) symbols, measures, in the dedicated resource pool, a channel busy ratio (CBR) based on resource elements of at least one of the SL-PRS symbols or the PSCCH symbols, and determine transmission parameters for the SL-PRS based on at least the CBR.