Up-sampling Correlator for BLE Time of Receipt Estimation
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Solution Overview
Problem
Legacy Bluetooth Low Energy (BLE) devices are not compliant with the BLE Indoor Positioning standard, which hinders accurate estimation of the time of receipt of a signal, thereby limiting the precision of distance estimation between communication devices.
Innovation Solution
A method and apparatus that involve generating a plurality of samples from a sampled signal using a higher sampling frequency, processing these samples with a correlator to create a correlation signal, and utilizing a timing estimator to accurately estimate the time of receipt of a transmission signal, incorporating a fractional delay interpolator and timing recovery loop for improved precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If legacy BLE devices use standard sampling frequency for signal processing, then device compatibility is maintained, but time of receipt estimation precision is insufficient
Solution Approach 1:
The patent applies preliminary action by performing up-sampling of the received signal before correlation processing. The up-sampler increases the sampling frequency from the original BLE rate (e.g., 1 MHz) to a higher rate (e.g., 4 MHz or 16 MHz), thereby preparing the signal with finer time resolution prior to timing estimation. This preliminary preprocessing enables more precise time of receipt estimation without requiring changes to the underlying BLE protocol or device architecture.
Solution Approach 2:
The patent introduces an up-sampling intermediary component that acts as a mediator between the received BLE signal and the timing estimation algorithm. This up-sampler serves as a bridge that transforms the signal into a form with enhanced temporal resolution, allowing legacy devices to achieve positioning precision comparable to compliant devices without modifying their fundamental operation. The up-sampled signal serves as an intermediate representation that preserves compatibility while enabling improved measurement capability.
2Measurement precision
If higher sampling frequency is used for signal processing, then time of receipt estimation accuracy is improved, but computational load increases
Solution Approach 1:
The patent applies partial action by performing up-sampling only on the critical portion of the signal that contains the timing information, rather than processing the entire signal at the higher rate. The up-sampling is focused on the preamble and synchronization regions where the time of receipt is encoded, allowing the system to achieve improved timing accuracy while limiting the extent of high-computation processing to only where necessary.
Solution Approach 2:
The patent substitutes a computationally intensive approach with a more efficient signal processing technique. Instead of using complex algorithms or hardware timers to achieve precise timing, the system replaces the mechanical timing measurement approach with signal-based correlation methods applied to up-sampled data. This substitution achieves high precision timing estimation through mathematical processing rather than direct hardware measurement, optimizing the balance between accuracy and computational energy consumption.
Data Source
AI summary
A first communication device generates a plurality of samples from a sampled signal. The sampled signal corresponds to a first sampling frequency, and the plurality of samples correspond to a second sampling frequency that is greater than the first sampling frequency. Additionally, the sampled signal corresponds to a transmission signal transmitted from a second communication device to the first communication device. The first communication device generates a correlation signal using the plurality of samples, and uses the correlation signal to generate an estimate of a time at which the transmission signal was received at the first communication device.