Sub-Nyquist PRS Sampling for Wideband 5G Positioning
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently handling overlapping channels with different priorities and in accurately determining the location of wireless devices using sub-Nyquist sampling techniques, particularly in 5G networks with increased data transfer speeds and large sensor deployments.
Innovation Solution
Implementing sub-Nyquist sampling for wideband positioning reference signals to enhance spectral efficiency and reduce latency, while using transmit and receive beamforming to improve signal processing and reduce multipath interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sub-Nyquist sampling is used for wideband positioning reference signals, then spectral efficiency is improved and latency is reduced, but signal processing complexity increases
Solution Approach 1:
The patent segments the wideband positioning reference signal into multiple sub-bands, each processed independently through separate filtering and FFT operations. This segmentation allows sub-Nyquist sampling to be applied to each sub-band individually, reducing the overall sampling rate while maintaining positioning accuracy and managing processing complexity through distributed computation.
Solution Approach 2:
The patent introduces an intermediary polyphase filter bank structure between the sub-Nyquist sampler and the FFT processor. This intermediary decomposes the sampled signal into multiple phase components, enabling efficient reconstruction of the wideband signal spectrum without requiring high-rate sampling, thus improving spectral efficiency while controlling processing complexity.
2Loss of time
If sub-Nyquist sampling is used for wideband positioning reference signals, then latency is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent applies preliminary bandpass filtering to isolate the positioning reference signal from other wireless signals before sub-Nyquist sampling. This preliminary action ensures that only the relevant signal components are sampled at the reduced rate, preventing aliasing of out-of-band interference and maintaining measurement precision despite the lower sampling rate.
Solution Approach 2:
The patent changes the sampling rate parameter dynamically, using sub-Nyquist sampling specifically for the positioning reference signal while maintaining higher sampling rates for other channels. This parameter change allows latency reduction for positioning operations without compromising the measurement precision required for accurate location determination.
3Measurement precision
If beamforming is used to reduce multipath interference, then positioning accuracy is improved, but device complexity increases
Solution Approach 1:
The patent implements partial beamforming by applying beamforming techniques only to the specific frequency resources allocated for positioning reference signals, rather than across the entire wideband spectrum. This partial application reduces the computational complexity of beamforming operations while still achieving the interference reduction needed to improve positioning accuracy for the critical positioning measurements.
Data Source
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AI summary
Disclosed are techniques for wireless communication. In an aspect, a band-pass filter of a radio frequency front end (RFFE) of a user equipment (UE) receives an analog radio frequency (RF) signal having a first bandwidth associated with a first sampling rate, the analog RF signal comprising a positioning reference signal (PRS). An analog-to-digital converter (ADC) of the UE samples the analog RF signal at a second sampling rate to generate a digital RF signal representing the analog RF signal, wherein the ADC operates at a second bandwidth lower than the first bandwidth, and wherein the second sampling rate is lower than the first sampling rate by an inverse of a folding factor for the first bandwidth. The digital RF signal is then output to a baseband processor of the UE.