RedCap UE Frequency Hopping for PRS Measurement
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Solution Overview
Problem
Reduced Capability (RedCap) User Equipment (UE) faces challenges in accurately determining its position due to power constraints, cost, and form factor limitations, which restrict its ability to accommodate high bandwidth Position Reference Signals (PRS).
Innovation Solution
The implementation of receive frequency hopping at RedCap UEs, allowing them to measure downlink PRS across multiple frequency hops, with capabilities such as maximum supported PRS bandwidth, possible number of frequency hops, maximum bandwidth per hop, and minimum hop overlap being indicated and configured.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RedCap UE uses narrow bandwidth to satisfy power and cost constraints, then device complexity and power consumption are reduced, but position determination accuracy deteriorates due to inability to accommodate high bandwidth PRS
Solution Approach 1:
The wide bandwidth PRS measurement task is segmented into multiple narrowband frequency hops. The UE measures PRS on individual narrow bandwidth components sequentially across different frequencies, then the network combines these segmented measurements to achieve accurate position determination. This segmentation allows RedCap UEs to measure high-bandwidth PRS without requiring simultaneous wide bandwidth reception capability.
Solution Approach 2:
The solution transitions from a single-dimension (frequency) measurement approach to a multi-dimensional approach by introducing time dimension through frequency hopping. Instead of measuring wide bandwidth at one frequency simultaneously, the UE hops across multiple frequencies in the time domain, effectively measuring the same PRS signal across the wide bandwidth spectrum through sequential narrowband measurements.
2Measurement precision
If RedCap UE increases bandwidth capability to measure high bandwidth PRS, then position determination accuracy improves, but power consumption and device cost increase
Solution Approach 1:
The power-intensive wide bandwidth PRS reception is segmented into multiple low-power narrowband frequency hop measurements. By measuring PRS on narrow bandwidth components sequentially rather than simultaneously across wide bandwidth, the UE significantly reduces instantaneous power consumption while still achieving accurate position determination through network-side combination of the segmented measurements.
Solution Approach 2:
Instead of requiring each RedCap UE to have expensive wide bandwidth reception hardware, the system creates virtual wide bandwidth measurement capability by copying and combining the narrowband measurements from multiple frequency hops. The network reconstructs the equivalent of a wide bandwidth PRS measurement from multiple narrowband copies taken at different frequencies.
3Device complexity
If RedCap UE uses narrow bandwidth PRS measurement, then device complexity is reduced, but measurement precision deteriorates due to insufficient bandwidth for high accuracy positioning
Solution Approach 1:
Multiple narrowband PRS measurements taken at different frequencies are merged to form an equivalent wide bandwidth measurement. The network combines the measurement results from multiple frequency hops, effectively merging the information content to achieve the positioning accuracy that would require wide bandwidth in a single measurement.
Solution Approach 2:
The solution compensates for narrow bandwidth by adding the time dimension through frequency hopping sequences. The UE performs narrowband measurements across multiple frequencies in the time domain, and the network combines these multi-dimensional measurements to achieve wide bandwidth equivalent positioning accuracy without requiring the UE to have wide bandwidth processing capability.
4Measurement precision
If RedCap UE performs frequency hopping to measure high bandwidth PRS, then position determination accuracy improves, but measurement time and complexity increase
Solution Approach 1:
The PRS measurement is structured as periodic frequency hopping across predetermined frequencies. The UE systematically hops through a sequence of frequency points in a periodic manner, measuring narrowband PRS at each hop. This periodic structure allows efficient planning and execution of the measurement campaign, and the network can predict when measurements will be completed based on the known hopping pattern and repetition periods.
Solution Approach 2:
The network pre-configures the frequency hopping pattern, repetition periods, and number of repetitions before the measurement campaign begins. This preliminary configuration allows the UE to efficiently execute the measurement sequence without real-time decision-making, reducing processing overhead and enabling optimized measurement timing that minimizes total measurement duration.
Data Source
AI summary
This disclosure provides systems, methods, and devices for wireless communication that support processing high bandwidth position references signals (PRSs) at a reduced capability (RedCap) User equipment (UE). The UE reports a frequency hopping capability and a measurement gap. In a first aspect, a method of wireless communication includes a method of wireless communication performed at a User Equipment. The UE transmits an indication of a capability of the UE to perform receive frequency hopping to measure a downlink positioning reference signal (DL-PRS), where the indication of the capability includes at least one of a maximum supported PRS bandwidth (BW) with frequency hopping, a possible number of frequency hops, maximum BW per hop, and minimum hop overlap. Optionally, the UE also transmits a report of a total PRS BW measured by the UE and/or an indication that a measurement with frequency hopping was performed. Other aspects and features are also claimed and described.