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2024 | Book

LoRa Localization

System Design and Performance Analysis


About this book

This book delves deep into the world of low-power Internet of Things (IoT) node positioning, in an era where IoT is revolutionizing connectivity and communication. It focuses on the critical aspect of accurate node positioning, which has transformative potential across various industrial applications. Specifically, this book explores how LoRa (Long Range) technology, known for its long-range wireless capabilities, low power consumption and cost-effectiveness. It can be harnessed to achieve precise and efficient node localization in both indoor and outdoor environments.

In Chapter 1, readers are introduced to the landscape of low-power IoT, providing background information, discussing network architecture and exploring the research landscape surrounding node positioning. Chapter 2 presents a modular hardware platform tailored for IoT applications and delves into wireless positioning techniques. Chapter 3 takes readers on a journey through wide area location using signal flight time and optimization techniques, emphasizing high accuracy, while keeping power consumption low. Chapter 4 showcases a cost-effective LoRa Mesh networking-based positioning system with wide-area coverage capabilities. This book continues by addressing the intricacies of indoor positioning challenges in Chapter 5, leveraging signal arrival angles and antenna array structures for precise localization. Chapter 6 explores fusion localization and tracking through mobile robots, enhancing position estimation and trajectory tracking in diverse environments. Finally, Chapter 7 offers a comprehensive conclusion, summarizing key insights and proposing future research directions in LoRa's fusion positioning for both indoor and outdoor scenarios.

This book is designed for researchers, engineers, and practitioners keen on unlocking the potential of low-power IoT node positioning and contributing to the advancement of IoT technologies. Advanced level students in computer science and electrical engineering interested in this topic will find this book useful as well.

Table of Contents

Chapter 1. Introduction
In this chapter, we first provide the background of Internet of Things, Low Power Wide Area Networks and location-based Internet of Things services. Based on the existing research work, we discuss the remaining problems and challenges related to indoor and outdoor localization and tracking of IoT nodes. Finally, we outline the scope and organization of this monograph.
Zhiguo Shi, Chaojie Gu, Shibo He, Kang Hu
Chapter 2. Wireless Localization Model and Hardware Foundation
In this chapter, we first introduce the basic principle of localization. Based on this, we analyze the distance-based localization model and angle-based localization model. Finally, we design a common hardware platform for various heterogeneous devices and protocols in IoT application and localization research.
Zhiguo Shi, Chaojie Gu, Shibo He, Kang Hu
Chapter 3. LoRa-Based Mobile Localization System
The node location has been regarded as one of the most important pieces of information to many novel applications of Internet of Things (IoT) in recent years. Typically, IoT nodes are always resource-constrained in terms of battery capacity, manufacturing cost, and computing ability. Thus, costly and energy-hungry localization techniques fall short for those applications. In this chapter, we present iLoc, a low-cost, low-power, and wide-area mobile localization system for IoT applications. iLoc is built on the emerging LoRa technologies and overcomes most disadvantages of the local localization techniques. Central to iLoc is a mobile anchor comprised of a simplified gateway and a commercial smartphone. To locate an IoT target node, the mobile anchor moves in a scheduled way, during which the gateway receives its locations from the smartphone and measures the time of flight (ToF) from the target node as well. The measurements are jointly optimized via fusing the RSSI and ToF in the ranging. Meanwhile, the inertial measurement unit, the GPS receiver, and the magnetometer are also fused in the anchor location estimation. We further design an iterative localization algorithm by judiciously deciding the locations of the anchor in an optimized way that not only minimizes the localization error bound but also reduces the system power consumption. We prototype the gateway and IoT node that cost less than 10 and 5 dollars, respectively. The extensive experiments demonstrate that iLoc achieves a mean localization error of 1.19 m and the power consumption is less than 1.06 mAh in an open outdoor environment.
Zhiguo Shi, Chaojie Gu, Shibo He, Kang Hu
Chapter 4. Wide-Area Localization System Based on LoRa Mesh
The positioning task of the Internet of Things (IoT) for outdoor environment requires that the node devices meet the requirements of low power consumption, long endurance and low cost, and that the positioning system can achieve high-precision positioning and wide-area coverage. Traditional IoT positioning technology cannot balance the cost, energy consumption and positioning performance well. Based on LoRa technology, LoRaWAPS, a low-cost, low-power and outdoor positioning system with multi-anchor wireless Mesh networking and multi-dimensional data fusion is designed in this chapter. To meet the need of positioning system, a low-power consumption and high-reliability LoRa Mesh protocol is proposed. Aiming at the problem that the accuracy of LoRa ranging is easily affected by the non-line-of-sight path propagation of signals, a distance estimation algorithm based on the fusion of time of flight (ToF) and received signal strength indicator (RSSI) multi-sampling data is proposed. Furthermore, a position estimation algorithm is designed to minimize a posteriori RSSI error for multi-anchor cooperative estimation scenarios. Based on the LoRa Mesh protocol, and the ranging and positioning algorithm, the prototype of LoRaWAPS is built and tested in the campus environment. The experimental results show that the proposed system can provide good location service for campus area. The peak power consumption of a single device in the system is less than 120 mW and the cost is less than $10, which can meet the outdoor positioning requirements of low-power and low-cost.
Zhiguo Shi, Chaojie Gu, Shibo He, Kang Hu
Chapter 5. Enable Angle of Arrival in LoRa for Efficient Indoor Localization
Though angle of arrival (AoA) has been recently adopted in many localization systems (e.g., WiFi, Bluetooth), it is still an open issue whether it can be enabled in LoRa for long-range localization. There are mainly two challenges: (1) current LoRa platform is not equipped with multiple RF channels for the array, and (2) the phase information is unavailable from the PHY layer. In this chapter, we propose a new method utilizing the ranging information for efficient AoA estimation, showing that multi-channel capability and phase information are not necessary. Specifically, we design a mobile gateway with a virtual array extended by an RF switch on a single channel. We further modify the ranging procedure by optimizing the hopping mechanism and packet format. To improve the AoA performance, we design a binary classification framework that achieves a theoretical error of 180/n degrees, where n is the number of antennas. Further, we propose a “rotate and follow” strategy to create more “virtual antennas” for the AoA estimation. The prototype localization system, RLoc, is built for both LoS and NLoS scenarios. Experiments show that RLoc achieves an average AoA estimation error of 2.4 degrees and is efficient in kilometer-level area, which outperforms to the existing localization systems.
Zhiguo Shi, Chaojie Gu, Shibo He, Kang Hu
Chapter 6. LoRa-Based Indoor Tracking System for Mobile Robots
The robot’s mobility and intelligence have expanded its application in recent years. Specifically, indoor tracking is a fundamental function of public service robots in nursing homes, hospitals, and warehouses. Existing vision-based tracking requires visual information, which may be unavailable and introduce privacy issues in practical deployment. To this end, in this chapter, we propose LTrack, a long-range tracking system based on LoRa, an emerging low-power wide-area networking (LPWAN) technology, with a single transceiver pair. Note that commodity LoRa devices cannot estimate the angle of arrival (AoA) of signals due to hardware limitations. We design a virtual circular antenna array in the mobile rotating anchor via a lightweight hardware modification to multiplex the only RF channel in the low-cost LoRa device. The difference of time of flight (TDoF) measured in the circular antenna array is fused with the rotating orientation to estimate the target AoA. We also redesign and optimize the primitive LoRa ranging engine based on systematic analysis. Further, we present a real-time mobile target tracking algorithm based on the Doppler frequency shift to combat the uncertainty introduced by the target movement. We have developed the prototype of LTrack, which consists of a mobile rotating anchor, a LoRa tag, and a commercial robot. The system is evaluated in both LOS and NOLS indoor scenarios. Experiments show that LTrack supports robust tracking with a median error of 0.12 and 0.45 m in a 137 \(\text{m}^2\) lab space and a 600 \(\text{m}^2\) corridor, respectively.
Zhiguo Shi, Chaojie Gu, Shibo He, Kang Hu
Chapter 7. Conclusion and Future Directions
In this chapter, we summarize the presented research and discuss some future directions for low-power IoT nodes localization.
Zhiguo Shi, Chaojie Gu, Shibo He, Kang Hu
LoRa Localization
Zhiguo Shi
Chaojie Gu
Shibo He
Kang Hu
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Electronic ISBN
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