Long-range (LoRa) can provide highly energy-efficient and cost-effective communications for low power wide area networks, playing an indispensable role in the Internet of Things (IoT). However, terrestrial LoRa networks cannot guarantee pervasive connectivity, especially in rural and remote areas. To tackle this problem, exploiting LoRa-based low Earth orbit (LEO) satellite IoT has garnered a growing interest in both academia and industry. In this paper, we provide a novel analytical framework based on spherical stochastic geometry (SG) for characterizing the uplink access probability of LoRa-based LEO satellite IoT. For practical modeling, multiple classes of LoRa end-devices (EDs) are taken into consideration, where each class of EDs is modeled by an independent Poisson point process (PPP). Both the channel characteristics of near-Earth satellite communications and the unique features of LoRa network are considered to derive closed-form analytical expressions for the uplink access probability. Numerical simulations validate the accuracy of our theoretical analysis and provide insightful guidelines for the practical design and implementation of LoRa-based LEO satellite IoT.

Recently, Long-Range (LoRa) based low Earth orbit (LEO) satellite Internet of Things (IoT) has garnered growing interest from both academia and industry, since it can guarantee pervasive connectivity in an energy-efficient and cost-effective manner. In this paper, we provide a novel spherical stochastic geometry (SG) based analytical framework for characterizing the uplink access probability of LoRa-based LEO satellite IoT system. Specifically, multiple classes of LoRa end-devices (EDs) are taken into consideration, where each class of LoRa EDs is modeled by an independent Poisson point process (PPP). Both the channel characteristics of the satellite-to-Earth communications and the unique features of the LoRa network are considered to derive closed-form analytical expressions for the uplink access probability of such a new paradigm. Moreover, the non-trivial impact of the spreading factor, the ED’s density, the orbit altitude, and the satellite effective beamwidth on the system performance is thoroughly investigated. Extensive numerical simulations are conducted, which not only validate the accuracy of our theoretical analysis but also provide useful insights into the practical design and implementation of LoRa-based LEO satellite IoT system.

LoRa is one of the most prominent low-power wide area network (LPWAN) technologies for Internet of Things (IoT) applications. As the core technique of LoRa physical (PHY) layer, chirp spread spectrum (CSS) modulation is employed to support low power and long range communications. Although it provides a compelling tradeoff between coverage and data rate, the relatively low-spectral efficiency (SE) is still a limiting factor for its extensive applications. In this article, we propose two enhanced group-based CSS modulation schemes, named in-phase and quadrature group-based CSS (IQ-GCSS) and time domain multiplexed group-based CSS (TDM-GCSS), which can achieve much higher SE than the conventional LoRa modulation. The transmitter architectures of our proposed modulation schemes are presented along with both coherent and noncoherent detection methods. Moreover, an overall performance analysis of our proposed schemes is provided in terms of bit error rate (BER) and computational complexity. Numerical results not only validate the accuracy of our theoretical analysis but also demonstrate substantial performance improvements of our proposed schemes in terms of effective throughput compared to the classical counterparts.

In recent years, long-range (LoRa) has become one of the most prominent low-power wide-area network (LPWAN) technologies for the Internet of Things (IoT), which is based on a proprietary chirp spread spectrum (CSS) modulation (i.e., LoRa modulation). However, with the ever-increasing transmission demands of various IoT applications, the low-data-rate issue of LoRa modulation has become a critical bottleneck for its extensive deployment. To address this issue, we first formulate a unified framework for CSS-based waveform design and propose a novel layered group-based CSS (LGCSS) modulation scheme to achieve much higher spectral efficiency (SE) and data rate, thus accommodating a wider range of IoT applications. The complete transmitter architecture of LGCSS modulation is presented along with both coherent and non-coherent detection methods. Moreover, a comprehensive performance analysis of our proposed scheme is conducted in terms of orthogonality, bit error probability (BEP), and computational complexity. Extensive numerical simulations are conducted to verify the effectiveness of our theoretical analysis and the superiority of our proposed scheme compared to the traditional counterparts.