Semtech Corporation

Olivier Bernard André Seller

Nicolas Sornin

Christophe Jean Jacques Devaucelle

Ludovic Champion

Baozhu Ning

Martin Wuthrich

Christophe Devaucelle

Fabio André Verna

Baozhou Ning

An extension of the LoRa modulation with an improved ranging mode. A master and a slave device exchange a request and a reply that contain sequences of chirps that are carefully aligned in time, frequency, and preferably also phase, such that the master device can ascertain the propagation delay to the slave by demodulating the reply. Request and reply include chirps having different slopes, preferably slopes of equal absolute value and opposite sign. The slope diversity permits an unbiased estimation of the Doppler shift.

Doppler ranging system

A LoRa transmitter and corresponding receiver where the detection sequence in the preamble is phase-modulated and includes an information that encodes the position in the preamble, such as a countdown index. Nodes that wake up to receive a scheduled download can determine from this information how far the end of the detection sequence is and manage their energy consumption accordingly. The phase modulation is compatible with legacy devices.

Transmitter, receiver, and method for chirp-modulated radio signals

A method of characterizing a LoRa modulated signal or any such signals with a plurality of chirps as symbols. It foresees sampling and storing the signal, determining a phase of at least one chirp in the signal, and determining a timing error and/or a frequency error based on the phase, The timing error is extracted by the height of a discontinuous step in the phase at the position of the cyclical shift, while the frequency error is obtained by the slope of the phase. The method can be applied to a dedicated receiver for the characterization of LoRa transmitters.

Spread spectrum receiver and testing method

A radio transmitting device configured to transmit a spread-spectrum radio signal wherein a carrier frequency changes in a predetermined set of radio channels according to a hopping sequence, the radio signal being organized in packets having each a header transmitted at a first channel in the hopping sequence comprising a detection sequence, and payload data encoding a message transmitted at following channels in the hopping sequence.

Wireless communication network and transceiver

Transmitter for chirp-modulated radio signals comprising a chirp generator configured to generate a series of chirp signals, wherein each chirp carries an element of information encoded as a cyclic shift, and has a phase encoding an error correction code dependent form the cyclic shift of the chirp, the transmitter further comprising a modulator configured to modulate the series of chirp onto a radio signal and a radio transmitter, transmitting the radio signal. receiver for chirp-modulated radio signals, comprising a clock unit and a demodulator configured for demodulating a series of received chirps signal, the demodulator having a dechirp unit, configured for determining a cyclic shift of each received chirp relative to a base chirp and an error correction code based on a phase of the received chirp, the receiver having a synchronism correction unit configured to detect and/or correct an error in the clock unit based on the error correction code.

A radio-transmitting device comprises a radio interface operating in a predetermined frequency band, operatively arranged for modulating a carrier having a frequency in the frequency band, while switching the frequency of the carrier among several hopping frequencies in the frequency band, according to a hopping sequence, to obtain a spread-spectrum modulated signal, wherein the spread-spectrum modulated signal includes, in a preamble portion, a plurality of sync words, each combined with at least one instance of a sequential index, the sync words being transmitted at different frequencies, and a data portion following the preamble portion and including a plurality of frequency hops.

Low-power, frequency-hopping, wide-area network with random medium access

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.

LoRa advanced receiver

Advanced modulation and demodulation schemes for LoRa or equivalent chirp spread spectrum transmissions, with differential modulation and symbol repetition improve the sensitivity in combination with soft demodulation methods.

Low power long-range radio

A hopping spread-spectrum wireless network for IoT applications operating in a predetermined frequency band, with mobile device that have unsynchronized local frequency references and receiving gateways that are capable of detecting whether modulated radio signals will collide in frequency in a collision time interval, and blanking the signals in the collision time. Preferably, the frequency band is subdivided into a sub-bands, and the mobile devices adapt the width of the sub-bands used for transmission based on a synchronization status indicative of the frequency error of the local frequency reference.

Collision mitigation in low-power, frequency-hopping, wide-area network

A hopping spread-spectrum wireless network for IoT applications with mobile device that have unsynchronized local frequency references. The transmitters use hopping sequences defined in term of the relative differences of frequencies, in such a manner that a receiver can determine the hopping sequence of a transmission despite the presence of a large frequency error.

Relative frequency hops in low-power, wide-area network

A ranging and positioning system comprising transmitters and receiver nodes communicating together by chirp-modulated radio signals, that have a ranging mode in which ranging exchange of signals takes place between a master device and a slave device that leads to the evaluation of the range between them. The slave is arranged for recognizing a ranging request and transmit back a ranging response containing chirps that precisely aligned in time and frequency with the chirps in the ranging requests, whereupon the master can receive the ranging response, analyze the time and frequency the chirps contained therein with respect to his own time reference, and estimate a range to the slave.

Ranging and positioning system

Method of timing, in a receiver, a radio signal generated in and transmitted from a transmitter, the radio signal comprising a series of frequency chirps, the system including: receiving the radio signal from the transmitter; synthesizing projection vectors comprising a series of frequency chirps that are a complex-conjugate image of those comprised in the radio signal the projection vectors being time-shifted relative to one another by determined shift intervals of time; multiplying the received radio signal by the projection vectors and accumulating the results; interpolating the accumulating results to determine a peak time shift.

Method and system of timing and localizing a radio signal

A wireless communication system, comprising one or several nodes (A) equipped by a wireless radio interface that is adapted for transmitting digital messages modulated in the form of a series of frequency chirps, for example, LoRa-modulated radio signals. The message is received simultaneously by several base stations (C, D, E), and a server (S) is arranged for dividing the frames by the diverse stations and recombining a corrected frame for the intended recipient (B) based on error codes. Advantageously, the base stations being adapt their timing error compensation strategy when the error codes indicate a corruption of the message.

Wireless communication system with macro diversity

A radio receiver for processing digital chirp spread-spectrum modulated signals that comprise a plurality of frequency chirps that are cyclically time-shifted replicas of a base chirp profile, said time-shifts being an encoded representation of a transmitted message. Includes a soft demapping unit that is adapted for working on fully populated as well as on partial modulation sets, and implements a timing error correction loop that acts back both in the time domain and in the frequency domain.

Low complexity, low power and long range radio receiver

A wireless communication method in a network comprising a plurality of nodes including ranging masters, broadcasting a chirp-modulated ranging requests, and ranging slaves slave, replying with thereto with chirp-modulated ranging responses, whereby mobile nodes can locate themselves passively by listening to the request/reply exchanges, based on the respective time differences of arrival.

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Sainte Soulle, France

Olivier Bernard André Seller