Isolating SDN Control Traffic with Layer-2 Slicing in 6TiSCH Industrial IoT Networks

Recent standardization efforts in IEEE 802.15.4-2015 Time Scheduled Channel Hopping (TSCH) and the IETF 6TiSCH Working Group (WG), aim to provide deterministic communications and efficient allocation of resources across constrained Internet of Things (IoT) networks, particularly in Industrial IoT (IIoT) scenarios. Within 6TiSCH, Software Defined Networking (SDN) has been identified as means of providing centralized control in a number of key situations. However, implementing a centralized SDN architecture in a Low Power and Lossy Network (LLN) faces considerable challenges: not only is controller traffic subject to jitter due to unreliable links and network contention, but the overhead generated by SDN can severely affect the performance of other traffic. This paper proposes using 6TiSCH tracks, a Layer-2 slicing mechanism for creating dedicated forwarding paths across TSCH networks, in order to isolate the SDN control overhead. Not only does this prevent control traffic from affecting the performance of other data flows, but the properties of 6TiSCH tracks allows deterministic, low-latency SDN controller communication. Using our own lightweight SDN implementation for Contiki OS, we firstly demonstrate the effect of SDN control traffic on application data flows across a 6TiSCH network. We then show that by slicing the network through the allocation of dedicated resources along a SDN control path, tracks provide an effective means of mitigating the cost of SDN control overhead in IEEE 802.15.4-2015 TSCH networks

Service-oriented wireless sensor networks and an energy-aware mesh routing algorithm

Service-oriented wireless sensor networks (WSNs) are being paid more and more attention because service computing can hide complexity of WSNs and enables simple and transparent access to individual sensor nodes. Existing WSNs mainly use IEEE 802.15.4 as their communication specification, however, this protocol suite cannot support IP-based routing and service-oriented access because it only specifies a set of physical- and MAC-layer protocols. For inosculating WSNs with IP networks, IEEE proposed a 6LoWPAN (IPv6 over LoW Power wireless Area Networks) as the adaptation layer between IP and MAC layers. However, it is still a challenging task how to discover and manage sensor resources, guarantee the security of WSNs and route messages over resource-restricted sensor nodes. This paper is set to address such three key issues. Firstly, we propose a service-oriented WSN architectural model based on 6LoWPAN and design a lightweight service middleware SOWAM (service-oriented WSN architecture middleware), where each sensor node provides a collection of services and is managed by our SOWAM. Secondly, we develop a security mechanism for the authentication and secure connection among users and sensor nodes. Finally, we propose an energyaware mesh routing protocol (EAMR) for message transmission in a WSN with multiple mobile sinks, aiming at prolonging the lifetime of WSNs as long as possible. In our EAMR, sensor nodes with the residual energy lower than a threshold do not forward messages for other nodes until the threshold is leveled down. As a result, the energy consumption is evened over sensor nodes significantly. The experimental results demonstrate the feasibility of our service-oriented approach and lightweight middleware SOWAM, as well as the effectiveness of our routing algorithm EAMR.<br /

Congestion and medium access control in 6LoWPAN WSN

In computer networks, congestion is a condition in which one or more egressinterfaces are offered more packets than are forwarded at any given instant [1]. In wireless sensor networks, congestion can cause a number of problems including packet loss, lower throughput and poor energy efficiency. These problems can potentially result in a reduced deployment lifetime and underperforming applications. Moreover, idle radio listening is a major source of energy consumption therefore low-power wireless devices must keep their radio transceivers off to maximise their battery lifetime. In order to minimise energy consumption and thus maximise the lifetime of wireless sensor networks, the research community has made significant efforts towards power saving medium access control protocols with Radio Duty Cycling. However, careful study of previous work reveals that radio duty cycle schemes are often neglected during the design and evaluation of congestion control algorithms. This thesis argues that the presence (or lack) of radio duty cycle can drastically influence the performance of congestion control mechanisms. To investigate if previous findings regarding congestion control are still applicable in IPv6 over low power wireless personal area and duty cycling networks; some of the most commonly used congestion detection algorithms are evaluated through simulations. The research aims to develop duty cycle aware congestion control schemes for IPv6 over low power wireless personal area networks. The proposed schemes must be able to maximise the networks goodput, while minimising packet loss, energy consumption and packet delay. Two congestion control schemes, namely DCCC6 (Duty Cycle-Aware Congestion Control for 6LoWPAN Networks) and CADC (Congestion Aware Duty Cycle MAC) are proposed to realise this claim. DCCC6 performs congestion detection based on a dynamic buffer. When congestion occurs, parent nodes will inform the nodes contributing to congestion and rates will be readjusted based on a new rate adaptation scheme aiming for local fairness. The child notification procedure is decided by DCCC6 and will be different when the network is duty cycling. When the network is duty cycling the child notification will be made through unicast frames. On the contrary broadcast frames will be used for congestion notification when the network is not duty cycling. Simulation and test-bed experiments have shown that DCCC6 achieved higher goodput and lower packet loss than previous works. Moreover, simulations show that DCCC6 maintained low energy consumption, with average delay times while it achieved a high degree of fairness. CADC, uses a new mechanism for duty cycle adaptation that reacts quickly to changing traffic loads and patterns. CADC is the first dynamic duty cycle pro- tocol implemented in Contiki Operating system (OS) as well as one of the first schemes designed based on the arbitrary traffic characteristics of IPv6 wireless sensor networks. Furthermore, CADC is designed as a stand alone medium access control scheme and thus it can easily be transfered to any wireless sensor network architecture. Additionally, CADC does not require any time synchronisation algorithms to operate at the nodes and does not use any additional packets for the exchange of information between the nodes (For example no overhead). In this research, 10000 simulation experiments and 700 test-bed experiments have been conducted for the evaluation of CADC. These experiments demonstrate that CADC can successfully adapt its cycle based on traffic patterns in every traffic scenario. Moreover, CADC consistently achieved the lowest energy consumption, very low packet delay times and packet loss, while its goodput performance was better than other dynamic duty cycle protocols and similar to the highest goodput observed among static duty cycle configurations

IEEE 802.15.4e: a Survey

Several studies have highlighted that the IEEE 802.15.4 standard presents a number of limitations such as low reliability, unbounded packet delays and no protection against interference/fading, that prevent its adoption in applications with stringent requirements in terms of reliability and latency. Recently, the IEEE has released the 802.15.4e amendment that introduces a number of enhancements/modifications to the MAC layer of the original standard in order to overcome such limitations. In this paper we provide a clear and structured overview of all the new 802.15.4e mechanisms. After a general introduction to the 802.15.4e standard, we describe the details of the main 802.15.4e MAC behavior modes, namely Time Slotted Channel Hopping (TSCH), Deterministic and Synchronous Multi-channel Extension (DSME), and Low Latency Deterministic Network (LLDN). For each of them, we provide a detailed description and highlight the main features and possible application domains. Also, we survey the current literature and summarize open research issues

A real-time packet scheduling system for a 6LoWPAN industrial application

Nowadays, the industrial Wireless Sensor Networks (WSN) are crucial for the monitoring and control of the modern smart factory floor that is relying on them for critical applications and tasks that were performed by wired systems in the past. For this reason, it is required that the transmission mechanisms of wireless sensor networks are efficient and robust and that they guarantee realtime responses with low data losses. Furthermore, it is required that they utilize common networking standards, such as the Internet Protocol (IP), that provides interoperability with already existing infrastructures and offers widely tested security and transmission control protocols. The theoretical part of this document focuses on the description of the current panorama of the industrial WSN, its applications, design challenges and standardizations. It describes the 6LoWPAN standard and the wireless transmission technology that it uses for its lower layers, the IEEE 802.15.4 protocol. Later, it describes the principles behind the wireless scheduling, a state-of-the-art in the IEEE 802.15.4 scheduled channel access and the features of the most used operating systems for WSN. The practical part presents the real-time packet scheduling system for a 6LoWPAN industrial application proposed by this thesis work that adapts the HSDPA scheduling mechanisms to the IEEE 802.15.4 beacon-enabled mode. The system implemented manages the channel access by allocating Guaranteed Time Slots to sensor nodes according to the priority given by three scheduling algorithms that can be selected according to the traffic condition of the network. The system proposed was programmed using Contiki OS. It is based on the eSONIA 6LoWPAN firmware developed for the European Research Project and it was deployed on the FAST WSN for testing. The results, discussion and conclusions are documented at the final sections of this part

BLE Connectivity and its Multi-hop Extension for IoT Applications

학위논문 (박사)-- 서울대학교 대학원 공과대학 전기·컴퓨터공학부, 2017. 8. 박세웅.Bluetooth Low Energy (BLE) is one of the representative low-power communication protocols that are being used to provide wireless connectivity for resource constrained devices as part of Internet of Things (IoT). Despite its commercial adoption, BLE's current use is limited to short-range applications due to the lack of research about its coverage extension. In this dissertation, we investigate two issues that need to be addressed for BLE's network coverage extension and also consider a new application scenario using a BLE-based multi-hop network. First, we tackle the BLE connection maintenance and energy consumption problems by adaptively controlling one of BLE's link layer parameters (TCI ) under dynamic channel condition. We formulate an optimization problem to find an optimal TCI and design a connection interval adaptation mechanism for BLE to achieve high energy efficiency while maintaining robust connectivity. We evaluate our proposed solutions through testbed experiments and simulation which shows that it reduces energy consumption of BLE in dynamic channel environments. Secondly, we consider a protocol architecture that aims to run IPv6 routing protocol for low power and lossy networks (RPL) over BLE to construct BLE-based multi-hop networks. We design an adaptation layer between BLE and RPL which tightly couples RPL and BLE operation. We implement the adaptation layer in a Linux kernel to realize RPL over BLE. Through extensive experiments in an indoor testbed, we evaluate the performance of RPL over BLE and compare the performance results with that of RPL over IEEE 802.15.4 which shows signicant improvement. Lastly, we consider a new application scenario of BLE using the coverage extension of BLE based on multi-hop networking. We propose a novel layered architecture of Wi-Fi and BLE that constructs an energy efficient and high data rate supportable ad-hoc network for disaster communication. We implement the proposed architecture in Linux kernel and evaluate the performance through our indoor testbed. The result shows that our proposed solution reduces the average power consumption of nodes in the testbed compared to a conventional Wi-Fi ad-hoc network.1 Introduction 1  1.1 Motivation 1  1.2 Related Work 4  1.2.1 Low power consumption of BLE 4  1.2.2 BLE multi-hop networking 5  1.3 Contributions and Outline 6  2 CABLE: Connection Interval Adaptation for BLE in Dynamic Wireless Environments 10  2.1 Introduction 10  2.2 Background and Problem Statement 14  2.2.1 Link layer operation 14  2.2.2 Connection loss due to supervision timeout 16  2.2.3 BLE protocol stack and connection interval set- ting 17  2.2.4 Problem of BLE with xed connection interval 19  2.3 Connection Interval Optimization 22  2.3.1 Problem formulation 22  2.3.2 Problem solution 26  2.4 CABLE System Design 29  2.4.1 PER estimator 30  2.4.2 TCI adjuster 33  2.5 Performance Evaluation 34  2.5.1 Simulation results 35  2.5.2 Experimental results 40  2.6 Summary 41  3 A Synergistic Architecture for RPL over BLE 43  3.1 Introduction 43  3.2 Background 47 3.2.1 RPL operation 47  3.2.2 BLE link layer operation 48  3.2.3 6LoWPAN for BLE 50  3.3 Design of RPL over BLE 52  3.3.1 Synergistic Network Architecture for RPL over BLE 52  3.3.2 DIO broadcast over advertising channels 54   3.3.3 Routing metric for RPL over BLE 57  3.3.4 RPL parent change with BLE connection man- agement 60  3.4 ALBER Implementation 61  3.5 Performance Evaluation 64  3.5.1 Testbed environments 64  3.5.2 Comparison of RPL over BLE vs. RPL over 802.15.4 65  3.5.3 Eect of varying connection interval 70  3.5.4 Eect of ECI-based routing metric 71  3.6 Summary 73  4 Wi-BLE: A Novel Layered Architecture of Wi-Fi & BLE Networks for Disaster Communications 74  4.1 Introduction 74  4.2 Background 78  4.2.1 Application requirements of ad-hoc networks for disaster communications 78  4.2.2 Candidate wireless interfaces for ad-hoc networks 79  4.2.3 Wi-BLE use scenario 79  4.3 Wi-BLE System Overview 80  4.3.1 Protocol Architecture 80  4.3.2 Operation Overview 81  4.4 MABLE: Mobile Ad-hoc for BLE 82  4.4.1 Routing protocol selection for MABLE 82  4.4.2 BLE Channel Usage for AODV over BLE 84  4.5 Wi-BLE: Wi-Fi Ad-hoc over BLE networks 88  4.5.1 Wi-BLE control packet delivery over BLE path 88  4.5.2 Routing protocol for Wi-BLE 89  4.5.3 Wi-Fi on/o control for energy saving 92  4.6 Implementation 92  4.7 Performance Evaluation 94  4.7.1 Testbed Environments 94  4.7.2 Hop distance &Throughput 95  4.7.3 Power Consumption 97  4.8 Summary 98  5 Conclusion 100  5.1 Research Contributions 100  5.2 Further Research Direction 102Docto

Congestion control in wireless sensor and 6LoWPAN networks: toward the Internet of Things

The Internet of Things (IoT) is the next big challenge for the research community where the IPv6 over low power wireless personal area network (6LoWPAN) protocol stack is a key part of the IoT. Recently, the IETF ROLL and 6LoWPAN working groups have developed new IP based protocols for 6LoWPAN networks to alleviate the challenges of connecting low memory, limited processing capability, and constrained power supply sensor nodes to the Internet. In 6LoWPAN networks, heavy network traffic causes congestion which significantly degrades network performance and impacts on quality of service aspects such as throughput, latency, energy consumption, reliability, and packet delivery. In this paper, we overview the protocol stack of 6LoWPAN networks and summarize a set of its protocols and standards. Also, we review and compare a number of popular congestion control mechanisms in wireless sensor networks (WSNs) and classify them into traffic control, resource control, and hybrid algorithms based on the congestion control strategy used. We present a comparative review of all existing congestion control approaches in 6LoWPAN networks. This paper highlights and discusses the differences between congestion control mechanisms for WSNs and 6LoWPAN networks as well as explaining the suitability and validity of WSN congestion control schemes for 6LoWPAN networks. Finally, this paper gives some potential directions for designing a novel congestion control protocol, which supports the IoT application requirements, in future work