A New LoRa-like Transceiver Suited for LEO Satellite Communications

Abstract

LoRa is based on the chirp spread spectrum (CSS) modulation, which has been developed for low power and long-range wireless Internet of Things (IoT) communications. The structure of LoRa signals makes their decoding performance extremely sensitive to synchronization errors. To alleviate this constraint, we propose a modification of the LoRa physical layer, which we refer to as differential CSS (DCSS), associated with an original synchronization algorithm. Based on this modification, we are able to demodulate the received signals without performing a complete frequency synchronization and by tolerating some timing synchronization errors. Hence, our receiver can handle ultra narrow band LoRa-like signals since it has no limitation on the maximum carrier frequency offset, as is actually the case in the deployed LoRa receivers. In addition, in the presence of the Doppler shift varying along the packet duration, DCSS shows better performance than CSS, which makes our proposed receiver a good candidate for communication with a low-Earth orbit (LEO) satellite.

Trends in LPWAN Technologies for LEO Satellite Constellations in the NewSpace Context

“…The long-range frequency-hopping spread spectrum (LR-FHSS) is an enhancement of LoRa that aims to improve the capacity and reliability of LoRa networks in high-devicedensity and data-traffic-congested environments [58]. The LR-FHSS provides more flexibility and scalability, offering adjustable data rates.…”

Implementation of A Low-Earth Orbit Satellite Chirped Preamble Detector

“…Eutelsat proposes to provide long-distance, low-bit-rate communication services for IoT using its satellites in low Earth orbit. Eutelsat aims to cover several modulations used in IoT, thus offering multi-modulation connectivity services, regardless of the waveform used (such as LoRa CSS [23], LoRa DCSS [7], LR-FHSS [9], ex-Sigfox [24], Ternwaves Golden Modulation [25], etc. ).…”

Resource Allocation for Cognitive LEO Satellite Systems: Facilitating IoT Communications

“…Thus, it is challenging to allocate a specified spectrum for LEO satellite-enabled IoT communications. On the other hand, unlike human-to-human communications, IoT communications are generally infrequent transmissions and occasionally exchange small amounts of data when transmitting [14][15][16]. In this regard, it would be wasteful to launch a dedicated satellite for IoT communications.…”