Low-power Wireless Networks Research Articles

Real Time Wireless Sensor Network (WSN) based Indoor Air Quality Monitoring System

This paper presents the development and implementation of a number of wirelessly connected sensor units to monitor indoor air quality parameters for real time visualisation and recording of the measured data. This is achieved by utilising infrared based sensor technology that measures carbon dioxide (CO2), temperature and humidity, low power wireless networking and Geo-statistic methods for spatial prediction. The platform consists an MBED LPC 1768 development board that retrieves data from the sensor unit and transmits it wirelessly using a ZigBee module to a central base station where it is analysed and stored. Spatial prediction is also performed in real time on live data. Initial measurements are performed in an office environment.

Atomic-SDN: Is Synchronous Flooding the Solution to Software-Defined Networking in IoT?

The adoption of Software Defined Networking (SDN) within traditional networks has provided operators the ability to manage diverse resources and easily reconfigure networks as requirements change. Recent research has extended this concept to IEEE 802.15.4 low-power wireless networks, which form a key component of the Internet of Things (IoT). However, the multiple traffic patterns necessary for SDN control makes it difficult to apply this approach to these highly challenging environments. This paper presents Atomic-SDN, a highly reliable and low-latency solution for SDN in low-power wireless. Atomic-SDN introduces a novel Synchronous Flooding (SF) architecture capable of dynamically configuring SF protocols to satisfy complex SDN control requirements, and draws from the authors' previous experiences in the IEEE EWSN Dependability Competition: where SF solutions have consistently outperformed other entries. Using this approach, Atomic-SDN presents considerable performance gains over other SDN implementations for low-power IoT networks. We evaluate Atomic-SDN through simulation and experimentation, and show how utilizing SF techniques provides latency and reliability guarantees to SDN control operations as the local mesh scales. We compare Atomic-SDN against other SDN implementations based on the IEEE 802.15.4 network stack, and establish that Atomic-SDN improves SDN control by orders-of-magnitude across latency, reliability, and energy-efficiency metrics.

Constructive Interference in 802.15.4: A Tutorial

Constructive interference (CI) can happen when multiple wireless devices send the same frame at the same time. If the time offset between the transmissions is less than 500 ns, a receiver will successfully decode the frame with high probability. CI can be useful for achieving low-latency communication or low-overhead flooding in a multi-hop low-power wireless network. The contribution of this paper is threefold. First, we present the current state-of-the-art CI-based protocols. Second, we provide a detailed hands-on tutorial on how to implement CI-based protocols on TelosB motes, with well documented open-source code. Third, we discuss the issues and challenges of CI-based protocols, and list open issues and research directions. This paper is targeted at the level of practicing engineers and advanced researchers and can serve both as a primer on CI technology and a reference to its implementation.

Long Range SigFox Communication Protocol Scalability Analysis Under Large-Scale, High-Density Conditions

In recent years, the IoT concept is more and more powerful, having set the goal of integrating billions of devices to the Internet. Thus, from this perspective, the interest allocated to low-power wireless networks of sensors is higher than ever. In this paper, the SigFox scalability is analyzed from the IoT concept point of view. In the scientific research, there are a series of papers which tackle the SigFox issues, oftentimes at a comparative study level, without evaluating the performance level of the communication protocol. This paper comes to fill this gap by creating a realistic SigFox communication model. Moreover, a developed and tested generator of SigFox traffic has been implemented, using SDRs. This allows the possibility of evaluating the performance level of WSN networks, of a large-scale high-density-type. Both of the suggested instruments represent the novelty of this paper. The obtained results show that the maximum number of sensors that can transmit data at the same time, using the proposed scenarios, is of approximately 100, in order to obtain a high level of performance when the number of available channels is 360. If we are to increase the number of sensors, an avalanche effect ensues which triggers the sharp decrease of the performance of the SigFox network. At the end of this work, a series of solutions are being suggested with the main purpose of increasing the performance level of large-scale, high-density SigFox networks.

TESLA: Traffic-Aware Elastic Slotframe Adjustment in TSCH Networks

Low-power wireless network for the emerging Internet of Things (IoT) should be reliable enough to satisfy the application requirements, and also energy-efficient for embedded devices to remain battery powered. Synchronized communication methods such as Time Slotted Channel Hopping (TSCH) have shown promising results for these purposes, achieving end-to-end reliability over 99% with low duty-cycles. However, they lack one thing: flexibility to support a wide variety of applications and services with unpredictable traffic load and routing topology due to “fixed” slotframe sizes. To this end, we propose TESLA, a traffic-aware elastic slotframe adjustment scheme for TSCH networks which enables each node to dynamically self-adjust its slotframe size at run time. TESLA aims to minimize its energy consumption without sacrificing reliable packet delivery by utilizing incoming traffic load to estimate channel contention level experienced by each neighbor. We extensively evaluate the effectiveness of TESLA on large-scale 110-node and 79-node testbeds, demonstrating that it achieves up to 70.2% energy saving compared to Orchestra (the de facto TSCH scheduling mechanism) while maintaining 99% reliability.

A New Method for Battery Lifetime Estimation Using Experimental Testbed for Zigbee Wireless Technology

Many Zigbee-based wireless sensor networks have been developed for outdoor applications such as agriculture monitoring. The main attractiveness of Zigbee wireless module is in its potential to set up self-organizing network that requires no network backbone and extremely low cost with low-power wireless networking. Many simulations have been performed for testing the capabilities of wireless communication device and the battery lifetime. However, the results from the simulation do not capture the actual environment effects and the simulators allow users to isolate certain factors by tuning to different parameters. This paper provides experimental results on actual voltage drop using Zigbee protocol devices when communicating temperature, humidity and soil moisture data using a 900mAh battery both in indoor and outdoor environments. It is observed that the wireless nodes are capable of relaying data up to 143 meters on unobstructed line of sights in an outdoor environment with some observation of packet drop. The results differ from previous researches that perform the experiments on shorter range which only covers 50 cm distance between transmitter node and receiver node for 2 bytes of data transfer. The paper proposes a new method for battery lifetime estimation which is derived from number of times data packet can be transmitted. This study also suggests to conduct experiment by including the environmental factors to capture the actual performance of wireless device and the impact to packet drop. The experiment concludes the suitability of Zigbee wireless communication for short-range applications of up to 143 meters which is significantly farther than other reported experiments.

A Review on the Contemporary Research on Radio Frequency Energy Harvesting

Radio Frequency harvesting has recently become one of the alternate approaches to power up low power wireless networks. This evolving technology opens the gate for positive energy renewal for wireless components. This paper presents a comprehensive review which includes all the important components in a RF energy harvesting system which are microstrip patch antennas, rectifier modules and power management modules. Different types of microstrip patch antennas and its designs and outputs are discussed. Rectifier modules with Schottky diodes operating under two different frequency bands are also compared and discussed. In addition, different methods of available power management circuits with different methods are also deliberated in this paper. This review also explores various key design issues and envisions some open research directions.

System for monitoring and supporting the treatment of sleep apnea using IoT and big data

Sleep apnea has become in the sleep disorder that causes greater concern in recent years due to its morbidity and mortality, higher medical care costs and poor people quality of life. Some proposals have addressed sleep apnea disease in elderly people, but they have still some technical limitations. For these reasons, this paper presents an innovative system based on fog and cloud computing technologies which in combination with IoT and big data platforms offers new opportunities to build novel and innovative services for supporting the sleep apnea and to overcome the current limitations. Particularly, the system is built on several low-power wireless networks with heterogeneous smart devices (i.e, sensors and actuators). In the fog, an edge node (Smart IoT Gateway) provides IoT connection and interoperability and pre-processing IoT data to detect events in real-time that might endanger the elderly’s health and to act accordingly. In the cloud, a Generic Enabler Context Broker manages, stores and injects data into the big data analyzer for further processing and analyzing. The system’s performance and subjective applicability are evaluated using over 30 GB size datasets and a questionnaire fulfilled by medicals specialist, respectively. Results show that the system data analytics improve the health professionals’ decision making to monitor and guide sleep apnea treatment, as well as improving elderly people’s quality of life.

Intelligent Containers Based on a Low-Power Sensor Network and a Non-Invasive Acquisition System for Management and Tracking of Goods

This paper presents a prototype of a system for intermodal freight transport with electronics management of goods. The system is based on low-power wireless networks connecting intelligent containers. The proposed intelligent container can be configured with different types of sensors inside. With the objective to preserve the sealing of the container, the data collected inside the container are transmitted through a metal communication channel based on ultrasonic techniques. Outside the container, the implemented system is composed by a long range and low-power scalable wireless network. Finally, a management subsystem has been designed for tracking, monitoring, and alarm reporting.

ETRT – Cross layer model for optimizing transmission range of nodes in low power wireless networks – An Internet of Things Perspective

Internet of Things network is managed by battery operated devices and low power radio links since they are referred to low power networks. In present communication era, many research works are concentrating on low power wireless network. Cross layer design is one of the acclaimed technique that decidedly improves the network performance. In this article, we come up with the cross-layer model that satisfies distinct network requirements and prolongs network lifetime. It integrates physical layer, data link layer (Media Access Control) and network layer in the protocol stack. In our model, a threshold value called ETRT (Expected Transmission Range Threshold) is introduced, which is computed with the help of routing information. Later, MAC based power control technique utilizes the ETRT value and assigns optimum transmission range for every node. The idea at the heels of proposed cross layer model is estimating the capability (ETRT value) of the particular node and assigning the suitable transmission power for every node, based on its capability (ETRT value). Hence, assigning optimum transmission power based on ETRT information prolongs the network lifetime with better reliability and Quality of Service(QoS). From our results, it is noticed that the ETRT based cross layer model performs twice better than the standard model.

Mitigating stealthy jamming attacks in low-power and lossy wireless networks

Jamming in wireless networks has advanced to be more stealthy and long-lasting with limited energy. Stealthy attackers transmit short jamming signals to become less detectable with less energy, and yet powerful enough to ruin entire packet transmission procedures. In this article, we deal with three types of stealthy attacks: ‘Reactive jamming’, ‘Jamming ACK’, and ‘Fake ACK’ attacks. These attacks are fatal to low-power and lossy wireless network (LLN) applications because they not only interfere with communication, but also cause LLN devices to quickly drain their batteries. To counter these attacks, we present Dodge-Jam, a lightweight anti-jamming technique suitable for LLN environments to address the stealthy jamming attacks. It protects ACK packet by switching the ACK exchange channel to a channel calculated based on the content of a data packet. Moreover, by partitioning a packet into multiple blocks and performing logical shifts of the blocks when retransmitting the packet, it helps the receiver recover the original packet from received multiple erroneous packets. We implement Dodge-Jam on practical embedded devices, and evaluate its performance through mathematical analysis and experiments on a multi-hop LLN testbed. Our results show that Dodge-Jam successfully avoids many stealthy jamming attacks, recovers jammed packets, and significantly improves packet delivery performance of single-hop and multi-hop networks with small overhead.1

Bandit Learning with Concurrent Transmissions for Energy-Efficient Flooding in Sensor Networks

Concurrent transmissions, a novel communication paradigm, has been shown to effectively accomplish a reliable and energy-efficient flooding in low-power wireless networks. With multiple nodes explo ...

Using SmartMesh IP in Smart Agriculture and Smart Building applications

We deploy two low-power wireless networks, one in a Smart Agriculture setting (a peach orchard), one in a Smart Building. Both networks use out-of-the-box SmartMesh IP technology to gather sensor values, as well as extensive network statistics. This article presents an in-depth analysis of the performance of both networks, and compares them. Nodes in both exhibit end-to-end reliability of 100%, with an expected lifetime between 4 and 8 years. We show how – contrary to popular belief – wireless links are symmetrical. Thanks to the use of Time Slotted Channel Hopping (TSCH), the network topology is stable, with at most 15 link changes on average per day in the network. We conclude that TSCH as implemented by SmartMesh IP is a perfectly suitable IoT solution for Smart Agriculture and Smart Building applications.

Implementation of Internet of Things (IoT) Based on IPv6 over Wireless Sensor Networks

Background & Objective: The Internet of things (IoT) refers to the connection of smart electronics devices to the Internet which enables these devices to collect and exchange data. Wireless sensor networks (WSNs) are effectively connected in an ad-hoc manner which consists of collaborative sensing devices that have limited resources capabilities. The sensor nodes can work together to organize real-time monitoring, sensing, and collecting information about the various environments within the event area. Method: Connecting WSNs to the internet will allow new generations of WSN applications to appear. One of the main standards of Internet of Things (IoT) over WSN is IPv6 over Low-power Wireless Personal Area Network (6LoWPAN) which has been designed to enable low-power wireless personal area network devices to integrate with IPv6 networks. This paper presents a 6LoWPAN test bed which has been conducted using MICAZ and TELOSB platforms. It implements TCP/IPv6 layers using Berkeley IP (BLIP) in TELOSB and MICAZ platforms. Conclusion: The finding in this paper opens up new Internet applications over WSNs. Keywords: Internet of Things, 6LoWPAN, WSNs, BLIP, electronic devices, sensor nodes.

Enhanced secure time synchronisation protocol for IEEE802.15.4e‐based industrial Internet of Things

Time synchronisation is a fundamental requirement for the IEEE802.15.4e-based industrial Internet of Things, allowing it to reach low-power and high-reliability wireless network through time synchronisation. If malicious adversaries launch time synchronisation attacks to IEEE802.15.4e-based networks, the entire network communication will be paralysed. In this study, the authors introduce two types of time synchronisation attacks: (i) absolute slot number (ASN) and (ii) timeslot template attack. In ASN attack, the new nodes may receive an incorrect ASN value, which prevents synchronisation with the typical network, while in the timeslot template attack, the malicious node can make the legitimate nodes calculate the error clock offset. The authors propose an enhanced secure time synchronisation protocol to defend against these attacks, which include Sec_ASN and TOF algorithm. The Sec_ASN and threshold filter (TOF) algorithms are used to defend against ASN attack and timeslot template attacks, respectively. Finally, the authors run a thorough set of simulations to assess the effectiveness of the proposed attacks as well as the proposed countermeasure. The results show that the attacks can significantly destroy the time synchronisation protocol, but can be successfully defended using the proposed mechanisms.

A current-reuse dual-channel bio-signal amplifier for WBAN nodes

This paper presents a dual-channel low-noise bio-signal amplifier for the low-power wireless body area network (WBAN) nodes. A dual-channel three-input current-reuse (DTCR) structure is proposed to optimize the noise performance of amplifier. The chopper-stabilized technique is employed to reduce 1/f noise and the offset voltage. Moreover, a high input impedance is achieved by using the pre-charge technique. In addition, a DC offset canceling loop is employed to suppress the electrode offset. The proposed amplifier is implemented in a standard 0.18 μm CMOS process with an active area of about 0.68 × 0.73 mm2. The experimental results demonstrate that an input referred noise of 1.12 μVrms has been achieved over a bandwidth from 0.35 Hz to 150 Hz. The total power consumption of each channel is about 1.44 μW at the supply voltage of 1.2 V. And the amplifier achieves an input impedance of about 200 MΩ, a CMRR of 111 dB at 50 Hz and a PSRR of 87.5 dB at 50 Hz.

Reducing hops without extra power: Impact of deployment height on low-power multihop wireless network

Many low-power wireless network system deployments are planned on a two-dimensional plane, while in reality, we live in a three-dimensional space. Therefore, although it is essential to well consider the impact of height on the overall wireless system performance, this aspect has often been overlooked if not neglected with simplifying assumptions. Our work takes an empirical effort in quantifying the impact of height on a low-power wireless system’s performance. Specifically, we use CC2420 radio–based wireless sensor network motes to quantify the impact of device deployment height on the connectivity and energy efficiency of low-power wireless networks. In addition, to validate the newly proposed sub-GHz low-power radios, we also experiment on the performance of CC1200 narrowband low-power radios to show that increasing a small amount of height in the node deployment phase can lead to drastic improvements in radio coverage and packet delivery performance. Such an observation can naturally lead to the reduction of network depth in a multihop wireless network for a given target deployment field; thus, it can potentially improve the energy efficiency of the overall system by suppressing the number of packet relay transmissions. We support our findings and observations through experiments on real embedded devices.

An Algorithm for Timely Transmission of Solicitation Messages in RPL for Energy-Efficient Node Mobility.

The IPv6 Routing Protocol for Low Power and Lossy Networks (RPL) was proposed for various applications of IPv6 low power wireless networks. While RPL supports various routing metrics and is designed to be suitable for wireless sensor network environments, it does not consider the mobility of nodes. Therefore, there is a need for a method that is energy efficient and that provides stable and reliable data transmission by considering the mobility of nodes in RPL networks. This paper proposes an algorithm to support node mobility in RPL in an energy-efficient manner and describes its operating principle based on different scenarios. The proposed algorithm supports the mobility of nodes by dynamically adjusting the transmission interval of the messages that request the route based on the speed and direction of the motion of mobile nodes, as well as the costs between neighboring nodes. The performance of the proposed algorithm and previous algorithms for supporting node mobility were examined experimentally. From the experiment, it was observed that the proposed algorithm requires fewer messages per unit time for selecting a new parent node following the movement of a mobile node. Since fewer messages are used to select a parent node, the energy consumption is also less than that of previous algorithms.

Accurate and Generic Sender Selection for Bulk Data Dissemination in Low-Power Wireless Networks

Data dissemination is a fundamental service offered by low-power wireless networks. Sender selection is the key to the dissemination performance and has been extensively studied. Sender impact metric plays a significant role in sender selection, since it determines which senders are selected for transmission. Recent studies have shown that spatial link diversity has a significant impact on the efficiency of broadcast. However, the existing metrics overlook such impact. Besides, they consider only gains but ignore the costs of sender candidates. As a result, existing works cannot achieve accurate estimation of the sender impact. Moreover, they cannot well support data dissemination with network coding, which is commonly used for lossy environments. In this paper, we first propose a novel sender impact metric, namely, γ, which jointly exploits link quality and spatial link diversity to calculate the gain/cost ratio of the sender candidates. Then, we develop a generic sender selection scheme based on the γ metric (called γ-component) that can generally support both types of dissemination using native packets and network coding. Extensive evaluations are conducted through real testbed experiments and large-scale simulations. The performance results and analysis show that γ achieves far more accurate impact estimation than the existing works. In addition, the dissemination protocols based on γ-component outperform the existing protocols in terms of completion time and transmissions (by 20.5% and 23.1%, respectively).

Adaptive Real-Time Communication for Wireless Cyber-Physical Systems

Low-power wireless technology promises greater flexibility and lower costs in cyber-physical systems. To reap these benefits, communication protocols must deliver packets reliably within real-time deadlines across resource-constrained devices , while adapting to changes in application requirements (e.g., traffic demands) and network state (e.g., link qualities). Existing protocols do not solve all these challenges simultaneously, because their operation is either localized or a function of network state, which changes unpredictably over time. By contrast, this article claims a global approach that does not use network state information as input can overcome these limitations. The Blink protocol proves this claim by providing hard guarantees on end-to-end deadlines of received packets in multi-hop low-power wireless networks, while seamlessly handling changes in application requirements and network state. We build Blink on the non-real-time Low-Power Wireless Bus (LWB) and design new scheduling algorithms based on the earliest-deadline-first policy. Using a dedicated priority queue data structure, we demonstrate a viable implementation of our algorithms on resource-constrained devices. Experiments show that Blink (i) meets all deadlines of received packets, (ii) delivers 99.97% of packets on a 94-node testbed, (iii) minimizes communication energy consumption within the limits of the underlying LWB, (iv) supports end-to-end deadlines of 100ms across four hops and nine sources, and (v) runs up to 4.1 × faster than a conventional scheduler implementation on popular microcontrollers.