A sub-mW IoT-endnode for always-on visual monitoring and smart triggering

This work presents a fully-programmable Internet of Things (IoT) visual sensing node that targets sub-mW power consumption in always-on monitoring scenarios. The system features a spatial-contrast $128\mathrm{x}64$ binary pixel imager with focal-plane processing. The sensor, when working at its lowest power mode ($10\mu W$ at 10 fps), provides as output the number of changed pixels. Based on this information, a dedicated camera interface, implemented on a low-power FPGA, wakes up an ultra-low-power parallel processing unit to extract context-aware visual information. We evaluate the smart sensor on three always-on visual triggering application scenarios. Triggering accuracy comparable to RGB image sensors is achieved at nominal lighting conditions, while consuming an average power between $193\mu W$ and $277\mu W$, depending on context activity. The digital sub-system is extremely flexible, thanks to a fully-programmable digital signal processing engine, but still achieves 19x lower power consumption compared to MCU-based cameras with significantly lower on-board computing capabilities.Comment: 11 pages, 9 figures, submitteted to IEEE IoT Journa

An Energy Aware and Secure MAC Protocol for Tackling Denial of Sleep Attacks in Wireless Sensor Networks

Wireless sensor networks which form part of the core for the Internet of Things consist of resource constrained sensors that are usually powered by batteries. Therefore, careful energy awareness is essential when working with these devices. Indeed,the introduction of security techniques such as authentication and encryption, to ensure confidentiality and integrity of data, can place higher energy load on the sensors. However, the absence of security protection c ould give room for energy drain attacks such as denial of sleep attacks which have a higher negative impact on the life span ( of the sensors than the presence of security features. This thesis, therefore, focuses on tackling denial of sleep attacks from two perspectives A security perspective and an energy efficiency perspective. The security perspective involves evaluating and ranking a number of security based techniques to curbing denial of sleep attacks. The energy efficiency perspective, on the other hand, involves exploring duty cycling and simulating three Media Access Control ( protocols Sensor MAC, Timeout MAC andTunableMAC under different network sizes and measuring different parameters such as the Received Signal Strength RSSI) and Link Quality Indicator ( Transmit power, throughput and energy efficiency Duty cycling happens to be one of the major techniques for conserving energy in wireless sensor networks and this research aims to answer questions with regards to the effect of duty cycles on the energy efficiency as well as the throughput of three duty cycle protocols Sensor MAC ( Timeout MAC ( and TunableMAC in addition to creating a novel MAC protocol that is also more resilient to denial of sleep a ttacks than existing protocols. The main contributions to knowledge from this thesis are the developed framework used for evaluation of existing denial of sleep attack solutions and the algorithms which fuel the other contribution to knowledge a newly developed protocol tested on the Castalia Simulator on the OMNET++ platform. The new protocol has been compared with existing protocols and has been found to have significant improvement in energy efficiency and also better resilience to denial of sleep at tacks Part of this research has been published Two conference publications in IEEE Explore and one workshop paper

An Adaptive Fault-Tolerant Communication Scheme for Body Sensor Networks

A high degree of reliability for critical data transmission is required in body sensor networks (BSNs). However, BSNs are usually vulnerable to channel impairments due to body fading effect and RF interference, which may potentially cause data transmission to be unreliable. In this paper, an adaptive and flexible fault-tolerant communication scheme for BSNs, namely AFTCS, is proposed. AFTCS adopts a channel bandwidth reservation strategy to provide reliable data transmission when channel impairments occur. In order to fulfill the reliability requirements of critical sensors, fault-tolerant priority and queue are employed to adaptively adjust the channel bandwidth allocation. Simulation results show that AFTCS can alleviate the effect of channel impairments, while yielding lower packet loss rate and latency for critical sensors at runtime.Comment: 10 figures, 19 page

Polling-Based Downlink Communication Protocol for LoRaWAN using Traffic Indication

학위논문 (석사)-- 서울대학교 대학원 : 공과대학 컴퓨터공학부, 2019. 2. 김종권.LPWAN (Low Power Wide Area Network) technologies such as LoRa and SigFox are emerging as a technology of choice for the Internet of Things (IoT) applications where tens of thousands of untethered devices are deployed over a wide area. In such operating environments, energy conservation is one of the most crucial concerns and network protocols adopt various power saving schemes to lengthen device lifetimes. For example, to avoid idle listening, LoRaWAN restricts downlink communications. However, the confined design philosophy impedes the deployment of IoT applications that require asynchronous downlink communications. In this thesis, we design and implement an energy efficient downlink communication mechanism, named TRILO, for LoRaWAN. We aim to make TRILO be energy efficient while obeying an unavoidable trade-off that balances between latency and energy consumption. TRILO adopts a beacon mechanism that periodically alerts end-devices which have pending downlink frames. We implement the proposed protocol on top of commercially available LoRaWAN components and confirm that the protocol operates properly in real-world experiments. Experimental results show that TRILO successfully transmits downlink frames without losses while uplink traffic suffers from a slight increase in latency because uplink transmissions should halt during beacons and downlink transmissions. Computer simulation results also show that the proposed scheme is more energy efficient than the legacy LoRaWAN downlink protocol.전력 공급이 제한적인 수 만개의 디바이스들을 이용하여 넓은 지역을 바탕으로 운영되는 사물인터넷 시스템을 구축하는 데에 있어서 LoRa, SigFox와 같은 저전력 광역 네트워크 기술(LPWA)이 주목받고 있다. 이러한 시스템 환경에서 에너지 절약은 중요한 관심사 중 하나이며 네트워크 프로토콜들은 다양한 절전 방식을 채택하여 디바이스의 수명을 보장하려 하고 있다. 예를 들어, 불필요한 대기 청취로 인한 에너지 손실을 방지하기 위해서 LoRaWAN은 다운링크 통신을 제한하고 있는데, 이러한 설계 철학은 비동기적인 다운링크 통신을 필요로 하는 IoT 애플리케이션의 요구 사항을 충족시키지 못하는 문제점을 가지고 있다. 따라서 본 논문에서는 LoRaWAN에서 다운링크를 효과적으로 컨트롤할 수 있도록 TRILO라는 에너지 효율적인 다운링크 통신 메커니즘을 설계하고 구현하였다. TRILO는 다운링크 프레임이 팬딩되어 있는 엔드 디바이스들의 리스트 정보를 주기적으로 네트워크에 알리는 비콘 메커니즘을 채택하였고, 서버와 디바이스들이 각각 정해진 순서에 따라 다운링크 전송 및 수신을 스케줄링하도록 하였다. 설계한 프로토콜이 제대로 동작하는지 검증하기 위해서 기존 LoRaWAN의 구성 요소 위에 제안된 프로토콜을 구현한 후 실제 테스트 베드를 구축하여서 실험을 진행하였다. 실험 결과에 따르면 TRILO는 기존 프로토콜의 업링크 통신 성능을 저해하지 않으면서도 추가적인 다운링크 프레임을 손실 없이 성공적으로 전송 및 수신하였고, 컴퓨터 시뮬레이션 결과 또한 제안된 기법이 기존의 LoRaWAN 다운링크 프로토콜보다 더 에너지 효율적으로 동작하는 것을 보여주었다.ABSTRACT ........................................................................................................... ⅰ CONTENTS ........................................................................................................... ⅲ LIST OF FIGURES ............................................................................................ ⅳ LIST OF TABLES .............................................................................................. ⅵ CHAPTER Ⅰ: Introduction ................................................................................ 1 CHAPTER Ⅱ: Related Work ............................................................................. 8 CHAPTER Ⅲ: A Primer on LoRa and LoRaWAN .................................. 11 CHAPTER Ⅳ: Downlink Communications Scheme .................................. 17 4.1 Comparison of Two Polling Schemes ..................................... 19 4.2 Proposed Downlink Communications Scheme ....................... 26 CHAPTER Ⅴ: Implementation ........................................................................ 28 CHAPTER Ⅵ: Evaluation ................................................................................. 31 6.1 Experimental Results .................................................................... 32 6.2 Simulation Results ......................................................................... 37 CHAPTER Ⅶ: Discussion ................................................................................. 42 CHAPTER Ⅷ: Conclusion ................................................................................. 45 BIBLIOGRAPHY ................................................................................................... 47 초록 ........................................................................................................................... 51Maste

Energy efficiency in short and wide-area IoT technologies—A survey

In the last years, the Internet of Things (IoT) has emerged as a key application context in the design and evolution of technologies in the transition toward a 5G ecosystem. More and more IoT technologies have entered the market and represent important enablers in the deployment of networks of interconnected devices. As network and spatial device densities grow, energy efficiency and consumption are becoming an important aspect in analyzing the performance and suitability of different technologies. In this framework, this survey presents an extensive review of IoT technologies, including both Low-Power Short-Area Networks (LPSANs) and Low-Power Wide-Area Networks (LPWANs), from the perspective of energy efficiency and power consumption. Existing consumption models and energy efficiency mechanisms are categorized, analyzed and discussed, in order to highlight the main trends proposed in literature and standards toward achieving energy-efficient IoT networks. Current limitations and open challenges are also discussed, aiming at highlighting new possible research directions

Energy-efficient wireless communication

In this chapter we present an energy-efficient highly adaptive network interface architecture and a novel data link layer protocol for wireless networks that provides Quality of Service (QoS) support for diverse traffic types. Due to the dynamic nature of wireless networks, adaptations in bandwidth scheduling and error control are necessary to achieve energy efficiency and an acceptable quality of service. In our approach we apply adaptability through all layers of the protocol stack, and provide feedback to the applications. In this way the applications can adapt the data streams, and the network protocols can adapt the communication parameters