KRATOS: An Open Source Hardware-Software Platform for Rapid Research in LPWANs

Long-range (LoRa) radio technologies have recently gained momentum in the IoT landscape, allowing low-power communications over distances up to several kilometers. As a result, more and more LoRa networks are being deployed. However, commercially available LoRa devices are expensive and propriety, creating a barrier to entry and possibly slowing down developments and deployments of novel applications. Using open-source hardware and software platforms would allow more developers to test and build intelligent devices resulting in a better overall development ecosystem, lower barriers to entry, and rapid growth in the number of IoT applications. Toward this goal, this paper presents the design, implementation, and evaluation of KRATOS, a low-cost LoRa platform running ContikiOS. Both, our hardware and software designs are released as an open- source to the research community.Comment: Accepted at WiMob 201

Synchronous and Concurrent Transmissions for Consensus in Low-Power Wireless

With the emergence of the Internet of Things, autonomous vehicles and the Industry 4.0, the need for dependable yet adaptive network protocols is arising. Many of these applications build their operations on distributed consensus. For example, UAVs agree on maneuvers to execute, and industrial systems agree on set-points for actuators.Moreover, such scenarios imply a dynamic network topology due to mobility and interference, for example. Many applications are mission- and safety-critical, too.Failures could cost lives or precipitate economic losses.In this thesis, we design, implement and evaluate network protocols as a step towards enabling a low-power, adaptive and dependable ubiquitous networking that enables consensus in the Internet of Things. We make four main contributions:- We introduce Orchestra that addresses the challenge of bringing TSCH (Time Slotted Channel Hopping) to dynamic networks as envisioned in the Internet of Things. In Orchestra, nodes autonomously compute their local schedules and update automatically as the topology evolves without signaling overhead. Besides, it does not require a central or distributed scheduler. Instead, it relies on the existing network stack information to maintain the schedules.- We present A2 : Agreement in the Air, a system that brings distributed consensus to low-power multihop networks. A2 introduces Synchrotron, a synchronous transmissions kernel that builds a robust mesh by exploiting the capture effect, frequency hopping with parallel channels, and link-layer security. A2 builds on top of this layer and enables the two- and three-phase commit protocols, and services such as group membership, hopping sequence distribution, and re-keying.- We present Wireless Paxos, a fault-tolerant, network-wide consensus primitive for low-power wireless networks. It is a new variant of Paxos, a widely used consensus protocol, and is specifically designed to tackle the challenges of low-power wireless networks. By utilizing concurrent transmissions, it provides a dependable low-latency consensus.- We present BlueFlood, a protocol that adapts concurrent transmissions to Bluetooth. The result is fast and efficient data dissemination in multihop Bluetooth networks. Moreover, BlueFlood floods can be reliably received by off-the-shelf Bluetooth devices such as smartphones, opening new applications of concurrent transmissions and seamless integration with existing technologies

Implementation of a LoRa Mesh library

LoRa is a popular communication technology in the Internet of Things (IoT) domain, providing low-power and long-range communications. Most LoRa IoT applications use the LoRaWAN architecture, which builds a star topology between LoRa end nodes and the gateway they connect to. However, LoRa can also be used for the communication between end nodes themselves, forming a mesh network topology. In this paper, we present a library that allows to integrate LoRa end nodes into a LoRa mesh network, in which a routing protocol is used. Thus, an IoT application running on these nodes can use the library to send and receive data packets to and from other nodes in the LoRa mesh network. The designed routing protocol is proactive, and maintains the routing table at each node updated by sending routing messages between neighboring nodes. The implemented library has been tested on embedded boards featuring an ESP32 microcontroller and a LoRa single-channel radio. By using our LoRa mesh library, nodes do not need to connect to a LoRaWAN gateway, but among themselves. This opens the possibility for new, distributed applications solely built upon tiny IoT nodes.This work was supported by the Ministry of Science and Innovation of the Spanish Government through the State Research Agency (AEI) under Project PID2019-106774RB-C21, Project PCI2019-111851-2 (LeadingEdge CHIST-ERA), and Project PCI2019-111850-2 (DiPET CHIST-ERA).Peer ReviewedPostprint (published version

The Contiki-NG open source operating system for next generation IoT devices

Contiki-NG (Next Generation) is an open source, cross-platform operating system for severely constrained wireless embedded devices. It focuses on dependable (reliable and secure) low-power communications and standardised protocols, such as 6LoWPAN, IPv6, 6TiSCH, RPL, and CoAP. Its primary aims are to (i) facilitate rapid prototyping and evaluation of Internet of Things research ideas, (ii) reduce time-to-market for Internet of Things applications, and (iii) provide an easy-to-use platform for teaching embedded systems-related courses in higher education. Contiki-NG started as a fork of the Contiki OS and retains many of its original features. In this paper, we discuss the motivation behind the creation of Contiki-NG, present the most recent version (v4.7), and highlight the impact of Contiki-NG through specific examples

Multi-channel Distributed MAC protocol for WSN-based wildlife monitoring

International audienceSeveral wild animal species are endangered by poaching. As a solution, deploying wireless sensors on animals able to send regular messages and also alert messages has been envisaged recently by several authorities and foundations. In that context, this paper proposes WildMAC, a multichannel, multihop wireless communication protocol for these specific wireless sensor networks that have to collect data from unknown large areas with different QoS requirements. WildMAC is a TDMA based MAC protocol that leverages long range communication properties to propose an efficient data collection mean. Its performance evaluation shows it meets QoS requirements

이기종 IoT 기기간 협력을 통한 네트워크 성능 향상

학위논문(박사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2022. 8. 박세웅.The Internet of Things (IoT) has become a daily life by pioneering applications in various fields. In this dissertation, we consider increasing transmission data rate with energy efficiency, extending transmission coverage with low power, and improving reliability in congested frequency bands as three challenges to expanding IoT applications. We address two issues to overcome these challenges. First, we design a layered network system with a new structure that combines Bluetooth Low Energy (BLE) and Wi-Fi networks in a multi-hop network. Based on the system, we propose methods to increase data rate with energy efficiency and extend transmission coverage in a low-power situation. We implement the proposed system in the Linux kernel and evaluate the performance through an indoor testbed. As a result, we confirmed that the proposed system supports high data traffic and reduces average power consumption in the testbed compared to the existing single BLE/Wi-Fi ad-hoc network in a multi-hop situation. Second, we tackle the adaptive frequency hopping (AFH) problem of BLE through cross-technology communication (CTC) and channel weighting. We design the AFH scheme that weights the channels used by BLE devices with improving reliability in the congested bands of both Wi-Fi and BLE devices. We evaluate the proposed scheme through prototype experiments and simulations, confirming that the proposed scheme increases the packet reception rate of BLE in the congested ISM band compared to the existing AFH algorithm.사물인터넷은 현재 다양한 영역에서 application을 개척하여 생활화되어 왔다. 이 학위 논문에서는 사물인터넷의 응용 사례 확장을 위해 에너지 효율적인 전송 속도 향상, 저전력 상황에서의 전송 범위 확장, 혼잡한 대역에서의 신뢰성 향상을 새로운 도전 과제로 삼고, 이러한 도전 과제를 극복할 두 가지 주제를 다룬다. 첫째, 다중 홉 네트워크 상황에서의 블루투스 저전력과 Wi-Fi 네트워크를 결합 한 새로운 구조의 계층적 네트워크 시스템을 설계하고 이에 기반한 에너지 효율적인 전송 속도 향상 및 저전력 상황에서의 전송 범위확장을 제안한다. 제안된 시스템은 Linux 커널에 구현하여 실내 테스트베드를 통해 성능을 평가한다. 결과적으로 제안 한 기법이 다중 홉 상황에서 기존 블루투스 저전력/Wi-Fi 단일 ad-hoc 네트워크와 비교하여 높은 데이터 트래픽을 지원하며, 테스트베드에서의 평균 전력 소비를 줄 이는 것을 확인한다. 둘째, Cross-technology Communication (CTC)과 채널 가중치를 통한 블루투스 저전력의 Adaptive Frequency Hopping (AFH) 문제를 해결한다. 최종적으로 블루투스 저전력 기기가 사용하는 채널에 가중치를 두는 AFH 기법을 설계하여 Wi-Fi 와 블루투스 저전력 기기가 모두 혼잡한 대역에서의 신뢰성을 향상한다. 프로토타입 실험과 시뮬레이션을 통해 제안한 기법이 기존의 AFH 기법과 비교하여 혼잡한 ISM 대역에서 블루투스 저전력의 패킷 수신율을 증가시키는 것을 확인한다.1 Introduction 1 1.1 Motivation 1 1.2 Contributions and Outline 2 2 Wi-BLE: On Cooperative Operation of Wi-Fi and Bluetooth Low Energy under IPv6 4 2.1 Introduction 4 2.2 Related Work 7 2.2.1 Multihop Connectivity for Wi-Fi or BLE 7 2.2.2 Multi-radio Operation 11 2.3 System Overview 13 2.3.1 Control Plane 13 2.3.2 Data Plane 16 2.3.3 Overall Procedure 16 2.4 MABLE: AODV Routing over BLE 17 2.4.1 BLE Channel Utilization 17 2.4.2 Joint Establishment of Route and Connection 20 2.4.3 Link Quality Metric for BLE Data Channels 22 2.4.4 Bi-directional Route Error Propagation 25 2.5 Wi-BLE: Wi-Fi Ad-hoc over BLE 27 2.5.1 Radio Selection 27 2.5.2 Routing and Radio Wake-up for Wi-Fi 30 2.6 Evaluation 32 2.6.1 BLE Routing 33 2.6.2 Wi-Fi Routing over BLE 35 2.6.3 Radio Selection 38 2.7 Summary 40 3 WBC-AFH: Direct Wi-Fi to BLE Communication based AFH 41 3.1 Introduction 41 3.2 Background 45 3.2.1 Frequency hopping in BLE 45 3.2.2 Cross Technology Communication 47 3.3 Proposed AFH 49 3.3.1 CTC based informing 50 3.3.2 Weighted channel select 51 3.3.3 Hopping set size optimization 52 3.3.4 WBC-AFH 54 3.4 Evaluation 57 3.4.1 Setup 57 3.4.2 Robustness 60 3.4.3 Reliability 61 3.5 Future Work 65 3.6 Summary 66 4 Conclusion 67박