An Open-Source LoRa Physical Layer Prototype on GNU Radio

LoRa is the proprietary physical layer (PHY) of LoRaWAN, which is a popular Internet-of-Things (IoT) protocol enabling low-power devices to communicate over long ranges. A number of reverse engineering attempts have been published in the last few years that helped to reveal many of the LoRa PHY details. In this work, we describe our standard compatible LoRa PHY software-defined radio (SDR) prototype based on GNU Radio. We show how this SDR prototype can be used to develop and evaluate receiver algorithms for LoRa. As an example, we describe the sampling time offset and the carrier frequency offset estimation and compensation blocks. We experimentally evaluate the error rate of LoRa, both for the uncoded and the coded cases, to illustrate that our publicly available open-source implementation is a solid basis for further research.Comment: GNU Radio source code available at: https://tcl.epfl.ch/resources-and-sw/lora-phy

Coded LoRa Frame Error Rate Analysis

In this work, we study the coded frame error rate (FER) of LoRa under additive white Gaussian noise (AWGN) and under carrier frequency offset (CFO). To this end, we use existing approximations for the bit error rate (BER) of the LoRa modulation under AWGN and we present a FER analysis that includes the channel coding, interleaving, and Gray mapping of the LoRa physical layer. We also derive the LoRa BER under carrier frequency offset and we present a corresponding FER analysis. We compare the derived frame error rate expressions to Monte Carlo simulations to verify their accuracy

Development of Universal Analyzer for LoRaWAN Using Software-Defined Radio

Práce se zabývá vývojem analyzátoru pro příjem LoRaWAN rámců ve frekvenční oblasti 868 MHz za použití softwarově definovaného rádia pro účely ladění a analýzy zachycené komunikace. Cílem práce je vyvinout software, který by byl schopen pro standardně používané konfigurace přijmout LoRaWAN rámce, demodulovat je a nakonec dekódovat, aniž by byla známá jediná informace o přijatém signálu. Za tímhle účelem byly vyvinuty metody pro detekci šířky pásma a činitele rozprostření, které dosahují vysoké úspěšnosti. Pro zrekonstruování dat byl implementován demodulátor a dekódér, kdy výstup je zprostředkován do softwaru Wireshark. V práci je hojně využíváno pokročilých prostředků pro digitální zpracování signálu jako například FFT a STFT, pracuje se též s analytickým signálem reprezentujícím průběh okamžitého kmitočtu přijatého signálu. Implementovaný software je podroben testu o několika krocích, kde je ověřena jeho funkčnost. V závěru je celé řešení zhodnoceno včetně jeho nedostatků, čímž se otevírají možné směry pro budoucí zkoumání.The thesis deals with the development of an analyzer for the reception of LoRaWAN frames in the 868 MHz frequency band using a software defined radio for the purposes of debugging and analysis of captured communication. The goal of the thesis is to develop software that would be able to receive LoRaWAN frames for standard configurations, demodulate them and finally decode them without knowing any preliminary information about received signal. For this purpose, methods for Bandwidth determination and Spreading Factor determination have been developed. Both methods achieved high success rates. To reconstruct the data, a demodulator and a decoder were implemented. The output of the decoder is passed into the Wireshark software. Advanced tools for digital signal processing such as FFT and STFT are extensively used in the work and an analytical signal representing the instantaneous frequency of the received signal is also used during signal processing. The implemented software is subjected to a test of several steps, where its functionality is verified. In the conclusion, the entire solution is evaluated, including its drawbacks, opening up possible directions for future research.440 - Katedra telekomunikační technikyvýborn