Energy Efficient and Reliable Wireless Sensor Networks - An Extension to IEEE 802.15.4e

Collecting sensor data in industrial environments from up to some tenth of battery powered sensor nodes with sampling rates up to 100Hz requires energy aware protocols, which avoid collisions and long listening phases. The IEEE 802.15.4 standard focuses on energy aware wireless sensor networks (WSNs) and the Task Group 4e has published an amendment to fulfill up to 100 sensor value transmissions per second per sensor node (Low Latency Deterministic Network (LLDN) mode) to satisfy demands of factory automation. To improve the reliability of the data collection in the star topology of the LLDN mode, we propose a relay strategy, which can be performed within the LLDN schedule. Furthermore we propose an extension of the star topology to collect data from two-hop sensor nodes. The proposed Retransmission Mode enables power savings in the sensor node of more than 33%, while reducing the packet loss by up to 50%. To reach this performance, an optimum spatial distribution is necessary, which is discussed in detail

Goodbye, ALOHA!

©2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The vision of the Internet of Things (IoT) to interconnect and Internet-connect everyday people, objects, and machines poses new challenges in the design of wireless communication networks. The design of medium access control (MAC) protocols has been traditionally an intense area of research due to their high impact on the overall performance of wireless communications. The majority of research activities in this field deal with different variations of protocols somehow based on ALOHA, either with or without listen before talk, i.e., carrier sensing multiple access. These protocols operate well under low traffic loads and low number of simultaneous devices. However, they suffer from congestion as the traffic load and the number of devices increase. For this reason, unless revisited, the MAC layer can become a bottleneck for the success of the IoT. In this paper, we provide an overview of the existing MAC solutions for the IoT, describing current limitations and envisioned challenges for the near future. Motivated by those, we identify a family of simple algorithms based on distributed queueing (DQ), which can operate for an infinite number of devices generating any traffic load and pattern. A description of the DQ mechanism is provided and most relevant existing studies of DQ applied in different scenarios are described in this paper. In addition, we provide a novel performance evaluation of DQ when applied for the IoT. Finally, a description of the very first demo of DQ for its use in the IoT is also included in this paper.Peer ReviewedPostprint (author's final draft

비대칭 전송전력 기반 무선 센서 시스템 연구

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2016. 2. 박세웅.대규모 마켓의 가격표 업데이트는 단순하고 반복적인 작업이지만, 여전히 대부분의 마켓에서 수동으로 이루어지고 있다. 수동 가격표 업데이트는 잦은 직원들의 실수로 인한 소비자들의 불만과 카운터의 계산 오류를 야기하므로, 상기 업데이트 과정을 자동화하면 많은 이익을 창출할 수 있다. 한편, 최근 전자 잉크와 같은 저전력 디스플레이 기술이 발전하면서 전자 무선 가격표 업데이트 서비스의 실현 가능성이 높아졌다. 본 논문에서 우리는 상기 전자 무선 가격표 업데이트 서비스를 위한 네트워크 아키텍쳐를 제안하고 테스트한다. 우리는 먼저 실제 마켓에서의 예비 실험들을 통해, 현존하는 네트워크 프로토콜들이 바쁜 마켓 환경에서 발생하는 독특한 문제들을 극복하지 못하고, 낮은 성능을 보인다는 것을 밝힌다. 우리는 상기 실험들을 통해 기술적인 도전과제들을 확인하고, 장애물과 인구가 많은 환경에서 하향링크 위주의 트래픽을 전송하기에 적합한 비대칭 전송 전력 기반 시스템인 MarketNet을 제안하여 상기 도전과제들을 해결한다. 우리는 하루에 5000명 이상의 손님이 방문하는 실내 마켓 환경에서 MarketNet의 성능을 평가한다. 상기 성능 평가의 결과들은 MarketNet이 타깃 환경(장애물이 많고 붐비는 마켓)에서 타깃 응용 분야(전자 무선 가격표 업데이트)를 적절히 지원할 수 있을 뿐만 아니라, RPL과 LPL과 같은 기존 프로토콜들보다 현저히 높은 패킷 전송률과 낮은 듀티사이클을 제공한다는 것을 보여준다.Updating price tags in a large-scale market is a recurrent task, still performed manually in most markets. Given that human-errors can easily lead to customer complaints and accounting inaccuracies, the ability to autonomously reconfigure price tags can be of significant benefit. With the introduction of low-power display techniques such as electronic-ink, applications of enabling electronic, wirelessly reconfigurable price tags show potential for future deployment. In this dissertation, we examine networking architectures that can be applied in such scenarios. Through a series of preliminary pilot studies in an actual supermarket, we show that the performance of existing protocols are not ready to overcome the unique challenges of busy market environments. We identify underlying technical challenges and propose MarketNet, an asymmetric transmission power-based system designed for densely populated, obstacle-rich, downwards traffic-oriented environments. We evaluate MarketNet in a large indoor market visited by 5000+ customers per day. Our results show that MarketNet addresses the challenges of the target application and environment, while achieving higher packet delivery performance with noticeably lower radio duty-cycles than existing protocols such as RPL and LPL.1 Introduction 1 1.1 Motivation 1 1.2 Related Work 4 1.2.1 Wireless Price Tag Update System 4 1.2.2 Wireless Systems Community 5 1.2.3 Wireless Network Community 10 1.3 Contributions and Outline 12 2 Target Application: Wireless and Remote Update of e-Price Tags 17 2.1 Price Representation 17 2.2 Application Scenario 19 2.3 System Requirements 22 3 Preliminary Study in Urban Crowded Markets 25 3.1 Introduction 25 3.2 Wireless Channel Characteristics 27 3.3 Performance of Pre-existing Protocols 38 3.3.1 RPL Operation 38 3.3.2 LPL Operation 42 3.3.3 Performance of RPL over LPL 44 3.4 Summary 48 4 MarketNet 1.0: Asymmetric Transmission Power-based Network 50 4.1 Introduction 50 4.2 Applicability of Asymmetric Transmission Power Networks 54 4.3 MarketNet1.0 System Design 58 4.3.1 Design Overview 58 4.3.2 Neighbor Forwarding over LPL 61 4.4 Mathematical Performance Analysis 66 4.4.1 Packet Reception Ratio 67 4.4.2 Latency 69 4.4.3 Power Consumption 70 4.5 Simulation Results 78 4.5.1 Latency 80 4.5.2 Packet Delivery Ratio 81 4.5.3 Power Consumption 82 4.6 Testbed Experiments 84 4.6.1 Implementation and Environment Setting 84 4.6.2 Downward Traffic Scenario 88 4.6.3 Mixed Traffic Scenario 93 4.7 Market Deployment 98 4.8 Summary 102 5 MarketNet 2.0: Network-wide Superframe Architecture 103 5.1 Introduction 103 5.2 MarketNet2.0 System Design 105 5.2.1 Network-wide Superframe Architecture 107 5.2.2 IPv6 and Routing Layers in MarketNet2.0 112 5.3 System Evaluation 115 5.3.1 Testbed Evaluations 115 5.3.2 Market Deployments 120 5.4 Non-technical but Practical Lessons 126 5.5 Summary 127 6 Conclusion 129 6.1 Research Contributions 129 6.2 Further Research Direction 131 Bibliography 135 초 록 150Docto

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

Performance Analyses and Improvements for the IEEE 802.15.4 CSMA/CA Scheme with Heterogeneous Buffered Conditions

Studies of the IEEE 802.15.4 Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) scheme have been received considerable attention recently, with most of these studies focusing on homogeneous or saturated traffic. Two novel transmission schemes—OSTS/BSTS (One Service a Time Scheme/Bulk Service a Time Scheme)—are proposed in this paper to improve the behaviors of time-critical buffered networks with heterogeneous unsaturated traffic. First, we propose a model which contains two modified semi-Markov chains and a macro-Markov chain combined with the theory of M/G/1/K queues to evaluate the characteristics of these two improved CSMA/CA schemes, in which traffic arrivals and accessing packets are bestowed with non-preemptive priority over each other, instead of prioritization. Then, throughput, packet delay and energy consumption of unsaturated, unacknowledged IEEE 802.15.4 beacon-enabled networks are predicted based on the overall point of view which takes the dependent interactions of different types of nodes into account. Moreover, performance comparisons of these two schemes with other non-priority schemes are also proposed. Analysis and simulation results show that delay and fairness of our schemes are superior to those of other schemes, while throughput and energy efficiency are superior to others in more heterogeneous situations. Comprehensive simulations demonstrate that the analysis results of these models match well with the simulation results

Wireless sensor network for health monitoring

Wireless Sensor Network (WSN) is becoming a significant enabling technology for a wide variety of applications. Recent advances in WSN have facilitated the realization of pervasive health monitoring for both homecare and hospital environments. Current technological advances in sensors, power-efficient integrated circuits, and wireless communication have allowed the development of miniature, lightweight, low-cost, and smart physiological sensor nodes. These nodes are capable of sensing, processing, and communicating one or more vital signs. Furthermore, they can be used in wireless personal area networks (WPANs) or wireless body sensor networks (WBSNs) for health monitoring. Many studies were performed and/or are under way in order to develop flexible, reliable, secure, real-time, and power-efficient WBSNs suitable for healthcare applications. To efficiently control and monitor a patient’s status as well as to reduce the cost of power and maintenance, IEEE 802.15.4/ZigBee, a communication standard for low-power wireless communication, is developed as a new efficient technology in health monitoring systems. The main contribution of this dissertation is to provide a modeling, analysis, and design framework for WSN health monitoring systems. This dissertation describes the applications of wireless sensor networks in the healthcare area and discusses the related issues and challenges. The main goal of this study is to evaluate the acceptance of the current wireless standard for enabling WSNs for healthcare monitoring in real environment. Its focus is on IEEE 802.15.4/ZigBee protocols combined with hardware and software platforms. Especially, it focuses on Carrier Sense Multiple Access with Collision Avoidance mechanism (CSMA/CA) algorithms for reliable communication in multiple accessing networks. The performance analysis metrics are established through measured data and mathematical analysis. This dissertation evaluates the network performance of the IEEE 802.15.4 unslotted CSMA/CA mechanism for different parameter settings through analytical modeling and simulation. For this protocol, a Markov chain model is used to derive the analytical expression of normalized packet transmission, reliability, channel access delay, and energy consumption. This model is used to describe the stochastic behavior of random access and deterministic behavior of IEEE 802.15.4 CSMA/CA. By using it, the different aspects of health monitoring can be analyzed. The sound transmission of heart beat with other smaller data packet transmission is studied. The obtained theoretical analysis and simulation results can be used to estimate and design the high performance health monitoring systems