# US 11,310,085 B2 · LoRa advanced receiver

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- Number: US 11,310,085 B2
- Document ID: US11310085B2
- Status: Granted
- Kind: B2
- Application number: 17/114,568
- Filed: 2020-12-08
- Published: 2021-06-17
- Granted: 2022-04-19
- Earliest claimed: 2019-12-11
- Assignees: Semtech Corporation
- Applicants: Semtech Corporation
- Inventors: Olivier Bernard André Seller; Christophe Jean Jacques Devaucelle
- Web page: https://patentgrep.com/patent/US11310085B2

## CPC

- H04B 1/69: Spread spectrum techniques
- H04L 27/103: {Chirp modulation (for spread spectrum techniques H04B1/69)}
- H04L 27/265: {Fourier transform demodulators, e.g. fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators (H04L27/26524 takes precedence)}
- H04L 27/2662: {Symbol synchronisation}
- H04B 2001/6912: {using chirp}
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A LoRa receiver for processing digital chirp spread-spectrum modulated signals with an advanced module for the determination of the timing error and/or of the frequency error arranged to estimate a position of a frequency discontinuity in each symbol, extract one or more frequency-continuous fragments out of each symbol, dechirp the coherent fragments, determine a timing error, and/or a frequency error, and/or a modulation value, and/or a SNR.

## Claims

### Claim 1

Radio receiver device comprising: a signal processor configured to process digital chirp spread-spectrum modulated signals that comprise a plurality of symbols constituted by frequency chirps that are cyclically time-shifted replicas of a base chirp profile, said time-shifts being an encoded representation of a transmitted message, wherein the signal processor is further configured to estimate a position of a frequency discontinuity in each symbol, extract one or more frequency-continuous fragments out of each symbol, dechirp the frequency-continuous fragments, determine a timing error, and/or a modulation value, and/or a SNR.

### Claim 2 (depends on 1)

The radio receiver device of claim 1, wherein the signal processor is further configured to choose dynamically one of the frequency-continuous fragments or the entire symbol for the determination of the timing error, and/or modulation value, and/or SNR, based on a detected SNR or modulation value.

### Claim 3 (depends on 1)

The radio receiver device of claim 1, the signal processor being further configured to select two coherent fragments covering a symbol, determine a timing error and/or a frequency error from the phase jumps present at two phase discontinuity at the boundaries between the selected coherent fragments.

### Claim 4 (depends on 1)

The radio receiver device of claim 1, the signal processor being further configured to compute Fourier transforms of the frequency-continuous fragments and to compute a timing error and/or a frequency error from the amplitudes and/or the phases of the Fourier transforms in the neighbourhood of modulation peaks.

### Claim 5 (depends on 1)

The radio receiver device of claim 1, the signal processor being further configured to determine a timing error and feeding the timing error to a Proportional/Integral tracking loop.

### Claim 6 (depends on 5)

The radio receiver device of claim 5, wherein coefficient of the Proportional/Integral tracking loop are dynamically adapted.

### Claim 7 (depends on 1)

The radio receiver device of claim 1, the signal processor being further configured to determine a timing error and compensate the timing error in the time domain and/or in the frequency domain.

### Claim 8 (depends on 1)

The radio receiver device of claim 1, the signal processor being further configured to determine a timing error and timestamp a received frame by combining an average of the timing error and a value of a counter sampled at a predetermined position in the received frame.

### Claim 9 (depends on 1)

A system comprising a plurality of gateways having each a receiver according to claim 1, the gateways being arranged to synchronise their time references by emitting regular transmission and listening to regular transmission from the other gateways, timestamp the received regular transmission.