Data acquisition in a chirp spread spectrum (CSS) signal may use a data alignment indicator of a single down chirp signal or single upchirp signal. A receiver may receive part or all of a preamble comprising a sequence of training chirps for symbol alignment followed by a single opposite chirp for data alignment. Training chirps may be processed through a fast-Fourier transform (FFT), and the values from the FFT may be accumulated. The accumulated values may exceed a threshold for detection. The receiver may align, based on the received chirps of the preamble and exceeding the threshold, its symbol reception. Using this symbol alignment, the receiver may await a single opposite chirp after the sequence of training chirps. The single opposite chirp may indicate data alignment. Upon receipt of the opposite chirp, the receiver may start data acquisition based on chirps following the single opposite chirp.

Devices and methods for enhancing forward error correction techniques for communications using chirp spread spectrum are disclosed. Systems, devices, and methods for error correction coding and decoding are described. On the coding side, K bits of data are sequentially loaded into an M bit by N bit (M×N) matrix in a first direction as Q sequences of D bits, each D bit row of data in the M×N matrix is coded with an error correction code to generate an M bit row of coded data, each Q bit column in the M×N matrix is coded with the error correction code to generate N bits of coded data, N sequences of M bits are sequentially unloaded from the M×N matrix in a second direction, and a chirp signal is generated having a plurality of chirps.

Aspects of the present disclosure are directed to injection locking and related apparatuses. As may be implemented in accordance with one or more embodiments, an apparatus includes a plurality of injection-locking circuits configured to receive an injection signal, each injection-locking circuit including a mixer and a lock-detection circuit. In each of the injection-locking circuits, the lock-detection circuit detects a lock-status relationship between the injection signal and a signal output from the injection-locking circuit. In response to the lock-status relationship indicating an unlocked condition, a phase/magnitude of the injection signal is adjusted. In response to the lock-status relationship indicating a locked condition, transmission of an FM continuous wave (FMCW) chirp signal is facilitated.

A multi-user system to simultaneously perform operations such as communication, RADAR, Light Detection and Ranging (LIDAR) and Relative Navigation (RELNAV). The techniques according to an embodiment includes generating a Fourier based orthogonal chirp sequence of length P, a prime number greater than the number of users targeted for communication. The orthogonal chirp sequence is based on an identifier, in the range of one to P−1, associated with one of the targeted users. The method further includes using the orthogonal chirp sequence to generate a spread user signal based on a message directed to the one targeted users. The method further includes generating a sequence of training pulses for insertion into the spread user signal to facilitate reception of the signal. The method further includes transmitting and receiving a reflection of the spread user signal from one of the targeted users, the reflection used to detect and range the user.

An apparatus comprises a frequency accumulator to produce a frequency ramp, and a symbol modulator to receive symbols and to add to the frequency ramp frequency offsets representative of the symbols, to produce a modulated frequency ramp for a modulated chirp. The apparatus includes a spreading factor controller to control a roll-over rate of the modulated frequency ramp responsive to spreading factor and frequency bandwidth control signals, to control a spreading factor and a frequency bandwidth of the modulated chirp. The apparatus includes a center frequency controller to control a center frequency of the modulated frequency ramp responsive to a center frequency control signal. The apparatus includes a phase accumulator to accumulate frequency samples of the modulated frequency ramp to produce phase samples corresponding to the modulated chirp, and a vector rotator to rotate the phase samples based on an input vector to produce a modulated chirp.

A LoRa device for communicating sensor signals in a low power wide area network (LPWAN) includes a physical layer using Hamming encoding and Gray indexing with chirp spread signal (CSS) modulation to encode and modulate the sensor signals and a medium access layer (MAC) including a compressive sensing sub-layer which reduces encoded, modulated signals to sparse vectors. A transmission packet is formed by combining the sparse vectors with a selected set of sparse vectors representing past measurements and the incoming velocity of the sensor signals. A receiver decompresses the transmission packet by reconstructing, at a sparse recovery sub-layer of a receiver MAC layer, the encoded, modulated sensor signals. A decoder path removes the CSS modulation and Gray indexing, and Hamming decodes the sensors signals.

A frequency synthesizer is described that includes: a voltage controlled oscillator, VCO; a VCO bias circuit, operably coupled to the VCO and configured to provide a controllable bias current of the VCO; a temperature sensor, located in the frequency synthesizer, configured to determine an operating temperature of the frequency synthesizer; an analog-to-digital converter, ADC, operably coupled to the temperature sensor and configured to provide a digital representation of the determined operating temperature; and a bias control circuit operably coupled and configured to provide a bias control signal to the VCO bias circuit based on the determined operating temperature of the frequency synthesizer. The VCO bias circuit is configured to adjust the controllable bias current applied to the VCO based on the bias control signal.

A method for allocating resources for a spread-spectrum communication system includes a plurality of communicating devices able to communicate with a server via at least one network access gateway, the method comprising the steps of: measuring a quality metric of the communication link for each communicating device over a given time window, determining at least one statistical indicator of the signal-to-interference ratio between each pair of communicating devices based on the quality metric, allocating each communicating device a spreading factor and at least one time slot to communicate, in accordance with a coexistence criterion dependent on the spreading factor and on the statistical indicator of the signal-to-interference ratio, the time resources being organized in the form of super-frames comprising first communication slots wherein several devices are able to communicate simultaneously using different spreading factors and second communication slots wherein several devices are able to communicate sequentially using the same spreading factor, the first communication slots being allocated to the devices that comply with the coexistence criterion, the second communication slots being allocated to the devices that do not comply with the coexistence criterion.

Data acquisition in a chirp spread spectrum (CSS) signal may use a data alignment indicator of a single down chirp signal or single upchirp signal. A receiver may receive part or all of a preamble comprising a sequence of training chirps for symbol alignment followed by a single opposite chirp for data alignment. Training chirps may be processed through a fast-Fourier transform (FFT), and the values from the FFT may be accumulated. The accumulated values may exceed a threshold for detection. The receiver may align, based on the received chirps of the preamble and exceeding the threshold, its symbol reception. Using this symbol alignment, the receiver may await a single opposite chirp after the sequence of training chirps. The single opposite chirp may indicate data alignment. Upon receipt of the opposite chirp, the receiver may start data acquisition based on chirps following the single opposite chirp.

A dual chirp modulation technique is presented for use in telecommunications. The technique includes: generating a first chirp signal ramping at a first rate; generating a second chirp signal ramping at a second rate which differs from the first rate; combining the first chirp signal with the second chirp signal to form a dual chirped signal; and transmitting, the dual chirped signal from a transmitter to a receiver. At least one first chirp signal, the second chirp signal or the dual chirped signal is preferably modulated. At the receiver, the dual chirped signal is correlated with a local chirp signal to help reject out-of-band interferers.