Mote Platform Research Articles

Token-Based Security for the Internet of Things With Dynamic Energy-Quality Tradeoff

In this paper, token-based security protocols with dynamic energy-security level tradeoff for Internet of Things (IoT) devices are explored. To assure scalability in the mechanism to authenticate devices in large-sized networks, the proposed protocol is based on the OAuth 2.0 framework, and on secrets generated by on-chip physically unclonable functions. This eliminates the need to share the credentials of the protected resource (e.g., server) with all connected devices, thus overcoming the weaknesses of conventional client–server authentication. To reduce the energy consumption associated with secure data transfers, dynamic energy-quality tradeoff is introduced to save energy when lower security level (or, equivalently, quality in the security subsystem) is acceptable. Energy-quality scaling is introduced at several levels of abstraction, from the individual components in the security subsystem to the network protocol level. The analysis on an MICA 2 mote platform shows that the proposed scheme is robust against different types of attacks and reduces the energy consumption of IoT devices by up to 69% for authentication and authorization, and up to 45% during data transfer, compared to a conventional IoT device with fixed key size.

An All-Digital Unified Physically Unclonable Function and True Random Number Generator Featuring Self-Calibrating Hierarchical Von Neumann Extraction in 14-nm Tri-gate CMOS

This paper describes a unified static/dynamic entropy generator based on a 512-b common entropy source (ES) array fabricated in 14-nm tri-gate CMOS with reconfigurable and adaptive post-processing circuits implemented on Arria 10 FPGA, targeted for flexible and secure privacy preserving mutual authentication on compact trusted mote platforms at the edge of internet of things. Several conditioning techniques that include temporal majority voting (TMV)-assisted ES array segregation with integrated bias tracking, three-way in-line self-calibration for tolerance to process–voltage–temperature variation, tri-level hierarchical Von Neumann (VN) extraction to maximize entropy harvesting, soft-dark bit masking for improving physically unclonable function (PUF) stability, and selective stress hardening to co-optimize the ES array for static-dynamic entropy with bias aware device aging enable simultaneous PUF and true random number generator (TRNG) operation with 1.48 and 0.56 Gb/s throughput, respectively, measured at 650 mV, 70 °C. The all-digital design with a compact layout footprint of 2114 $\mu \text{m}^{2}$ facilitates seamless integration in area constrained system-on-chips while achieving: 1) 25% area savings over conventional separate PUF and TRNG implementations; 2) cryptographic quality TRNG stream that passes all NIST randomness tests with 0.38 average p-value; 3) $1.6\times $ higher extractor performance at $9\times $ lower area with 750-gate hierarchical VN circuit over conventional light-weight entropy extractors; 4) 0.9996/0.99997 static/dynamic Shannon entropy indicating unbiased PUF/TRNG streams; 5) ultra-low energy consumption of 2.5 and 0.46 pJ/bit measured at 650 mV, 70 °C in TRNG and PUF modes; 6) 40% higher TRNG throughput with three-way self-calibration featuring coarse-grain column swap, fine-grain incremental ES substitution, and residual entropy recycling; 7) resistance to power injection attacks as measured by 64% higher performance over un-calibrated design in the presence 200-mV supply noise; 8) 2.8% PUF bit-error measured at 0.55–0.75 V, 25 °C–110 °C with 15-way TMV and soft dark-bit masking over a window of 100 cycles; 9) $14.8\times $ inter and intra-PUF hamming distance separation; and 10) 56% reduction in discarded ES cells with selective stress hardening to opportunistically reinforce/nullify pre-existing bias in PUF/TRNG candidate cells. To our knowledge, this is the first reported unified PUF-TRNG implementation enabling simultaneous generation of high-entropy chip-ID and encryption keys in real time.

Performance Analysis of Time Synchronization Protocols on Different Commercial Mote Platforms

Wireless sensor networks (WSNs) have astounding advantages for monitoring environmental properties and object movement. The small size of sensors in a WSN is used very craftily and is ideal for obscured observations. However, for these observations, the sensor clocks should be synchronized within a few microseconds of each other to accurately determine the point of origin. This paper shows the performance analysis of different time synchronization protocols over different mote platforms. Time synchronization protocols like Reference Broadcast Synchronization (RBS), Timing-Sync Protocol for Sensor Networks (TPSN), Hybrid Energy-Aware protocol and Minimum Distance Clustering Hybrid Synchronization (MDCHS) protocol are simulated over different mote platforms viz., MICA2Dot433, MICA2Dot916, MICAz and TelosB. Different performance metrics like Energy Usage and Synchronization Time are used to analyse the performance of these protocols. The model is simulated using MATLAB. The effects of changes in network topology and node density are also studied.

Sparsity Based Efficient Cross-Correlation Techniques in Sensor Networks

Cross-correlation is a popular signal processing technique used in numerous location tracking systems for obtaining reliable range information. However, its efficient design and practical implementation has not yet been achieved on mote platforms that are typical in wireless sensor network due to resource constrains. In this paper, we propose StructS-XCorr : cross-correlation via structured sparse representation, a new computing framework for ranging based on $\ell _1$ -norm minimization [1] and structured sparsity. The key idea is to compress the ranging signal samples on the mote by efficient random projections and transfer them to a central device; where a convex optimization process estimates the range by exploiting the sparse signal structure in the proposed correlation dictionary. Through theoretical validation, extensive empirical studies and experiments on an end-to-end acoustic ranging system implemented on resource limited off-the-shelf sensor nodes, we show that the proposed framework can achieve up to two orders of magnitude better performance compared to other approaches such as working on DCT domain and downsampling. Compared to the standard cross-correlation, it is able to obtain range estimates with a bias of 2-6 cm with 30 percent and approximately 100 cm with 5 percent compressed measurements. Its structured sparsity model is able to improve the ranging accuracy by 40 percent under challenging recovery conditions (such as high compression factor and low signal-to-noise ratio) by overcoming limitations due to dictionary coherence.

Communication performances of IEEE 802.15.4 wireless sensor motes for data-intensive applications: A comparison of WaspMote, Arduino MEGA, TelosB, MicaZ and iMote2 for image surveillance

In this paper, we are investigating the communication performances of low-resources sensor motes that are commonly found in recent smart cities test-beds or used by the research community. We focus here on 802.15.4 radio and we will present a performance study of sending and receiving capabilities of Libelium WaspMote, Arduino-based motes, Telosb-based motes, MicaZ motes and iMote2 motes when a large number of packets needs to be sent from sources to sink node. We provide measures for the minimum time spent in send procedure, minimum time needed to read data into application memory space and maximum sender/receiver throughput. We will highlight the main sources of delays assuming no flow control nor congestion control to determine the best case performance level. Our contribution is therefore in determining the maximum realistic level of performance for commonly found mote platforms in order to predict end-to-end performances for surveillance applications. Finally, we illustrate our study with an image transmission test case for intrusion detection surveillance applications.

DZ50: Energy-efficient Wireless Sensor Mote Platform for Low Data Rate Applications

A low cost and energy e_cient wireless sensor mote platform for low data rate monitoring applications is presented. The new platform, named DZ50, is based on the ATmega328P micro-controller and the RFM12b transceiver, which consume very low energy in low-power mode. Considerable energy saving can be achieved by reducing the power consumption during inactive (sleep) mode, notably in low data rate applications featured by long inactive periods. Without loss of generality, spot monitoring in a Smart Parking System (SPS) and soil moisture in a Precision Irrigation System (PIS) are selected as typical representative of low data rate applications. The performance of the new platform is investigated for typical scenarios of the selected applications and compared with that of MicaZ and TelosB. Energy measurements have been carried out for di_erent network operation states and settings, where the results reveal that the proposed platform allows to multiply the battery lifetime up to 7 times compared to MicaZ and TelosB motes in 10s sampling period scenarios.

A Simulation Platform for Evaluating RFID and WSN’s Energy Efficiencies

Advances in the wireless, RFID and sensor technologies has given rise to a plethora of diverse WSN motes that can be used in association with numerous applications. Experimenting with new MAC algorithms and various functionalities on a real sensor network to obtain energy efficiency is both time consuming and expensive especially when these different mote platforms are deployed in one application. Generally Simulators are used to approximate the performance of MAC protocols. Out of the numerous simulators available, none can simulate the energy efficiencies given different types of motes and environments in one application. Hence, the need of a simulation platform for a mix deployment of different types of WSNs and RFIDs is felt to access application performance requirements while curtailing energy consumption to enhance application lifetime. In this paper, we presents an extension of our effort EnergySim [1], which is a simulation platform developed dedicatedly for evaluating energy efficiencies. In this paper we have discussed the simulation modes, methodology and architecture of our proposed simulator with some future extensions presented at the end of the paper.

COMPARISON OF FEASIBILITY OF RISK MONITORING IN BUILDINGS IN TWO WIRELESS SENSOR NETWORK: MICA MOTE AND MEMS

In this paper feasibility of risk monitoring of buildings in two wireless sensor network is presented, firstly by using MICA Mote and then by MEMS. Also, it will be verified that the MEMS sensors are superior as it provides high quality sensor data and no data loss as compared to MICA Mote. In order to assess earthquakes the structures is monitored firstly by using a smart sensor based on the Berkeley Mote platform. The Mote has on-board microprocessor and ready-made wireless communication capabilities. In this paper, the performance of the Mote is investigated through shaking table tests employing a two-story steel structure. The feasibility of risk monitoring for buildings is also discussed. In building monitoring using MEMS, a low power wireless network employing capacitive MEMS which is custom-developed,3D accelerated sensor and a low power readout ASIC is used at the sensor nodes. After the the earthquake, the plastic hinge activation of structure is being measured using MEM sensor either periodically or on demand by the base station. During an earthquake the accelerometers are used to measure the seismic response of the structure. The seismic response is recorded by the accelerometer based on the local acceleration data and remote triggering from the base station. The base station is based on acceleration data from multiple sensors across the structure. In a 800 MHZ band, a low power architecture had been implemented over an 802.15.4 MAC.

Link Performance Enhancement for Image Transmission with FEC in Wireless Sensor Networks

Wireless Sensor Networks (WSN) is formerly created to support text-based data communication. However, by improving link level mechanism of WSN with Error Control Coding (ECC), reliable multimedia transmission could be realized. This paper addresses the performance issue of transferring multimedia data, particularly still image data, using real sensor motes platform. An X-ray image is transferred from one mote to other mote in one hop scenario. Forward Error Correction (FEC) and interleaving technique are used to design the code that capable of handling both erasure and noise in the received packet. The results show that erasure code can effectively combat the effect of random noise in one packet despite its number as well as recover small quantity of lost packet. Furthermore, the scheme can increase the image PSNR (Peak Signal to Noise Ratio) up to 18.41 dB as compared to the uncoded counterpart.

A localized algorithm for Structural Health Monitoring using wireless sensor networks

Structural Health Monitoring (SHM) has been proving to be a suitable application domain for wireless sensor networks, whose techniques attempt to autonomously evaluate the integrity of structures, occasionally aiming at detecting and localizing damage. In this paper, we propose a localized algorithm supported by multilevel information fusion techniques to enable detection, localization and extent determination of damage sites using the resource constrained environment of a wireless sensor network. Each node partakes in different network tasks and has a localized view of the whole situation, so collaboration mechanisms and multilevel information fusion techniques are key components of this proposal to efficiently achieve its goal. Experimental results with the MICAz mote platform showed that the algorithm performs well in terms of network resources utilization.

Remote corrosion monitoring of the RC structures using the electrochemical wireless energy-harvesting sensors and networks

Essentially, the corrosion process of the steel bar in reinforcing concrete structures is a series of electrochemical reactions. Therefore, the released energy during these reactions provides the opportunities to identify the corrosion status and power the wireless corrosion monitoring sensors. Furthermore, the recognition of the corrosion status has been realized with active monitoring techniques (AMTs) and passive monitoring techniques (PMTs). Additionally, the sensor mote platform that harvests the corrosion energy has been designed for corrosion monitoring, and then how to network these sensors to remotely access the corrosion data has been discussed. The preliminary experiment has been conducted to validate the micro corrosion energy.

On enabling cooperative communication and diversity combination in IEEE 802.15.4 wireless networks using off-the-shelf sensor motes

This paper presents the `Generalized Poor Man's SIMO System' (gPMSS) which combines two approaches, cooperative communication and diversity combination, to reduce packet losses over links in wireless sensor networks. The proposed gPMSS is distinct from previous cooperative communication architectures in wireless sensor networks which rely on a relay channel, and also distinct from implementations in 802.11 networks that require a wired infrastructure or hardware changes for cooperation. gPMSS foregoes the need for any changes to mote hardware and it works within the current IEEE 802.15.4 standard. We describe the gPMSS protocol that governs the cooperation between receivers. Three variants are evaluated including selection diversity, equal gain and maximal ratio combining. First, we demonstrate gPMSS on bit error traces in a fully reproducible manner. This is followed by an implementation of gPMSS in C# on the .NET Micro Framework edition of the recently released Imote2 mote platform. We demonstrate by means of experiments an increase in the packet reception rate from 22---30% to 73---76%, a relative increase of 150---245%. We also analyzed the power consumed by the transmitter per delivered packet and observe a reduction of up to 68%. We also take into account the retry limit of the IEEE 802.15.4 protocol and demonstrate that gPMSS is able to provide 99% packet delivery at the protocol's default retry parameters against 65---75% without it.

An Interlaced Extended Information Filter for Self-Localization in Sensor Networks

Wireless Sensor Networks (WSNs) are at the forefront of emerging technologies due to the recent advances in Microelectromechanical Systems (MEMSs). The inherent multidisciplinary nature of WSN attracted scientists coming from different areas stemming from networking to robotics. WSNs are considered to be unattended systems with applications ranging from environmental sensing, structural monitoring, and industrial process control to emergency response and mobile target tracking. Most of these applications require basic services such as self-localization or time synchronization. The distributed nature and the limited hardware capabilities of WSN challenge the development of effective applications. In this paper, the self-localization problem for sensor networks is addressed. A distributed formulation based on the Information version of the Kalman Filter is provided. Distribution is achieved by neglecting any coupling factor in the system and assuming an independent reduced-order filter running onboard each node. The formulation is extended by an interlacement technique. It aims to alleviate the error introduced by neglecting the cross-correlation terms by "suitably” increasing the noise covariance matrices. Real experiments involving MICAz Mote platforms produced by Crossbows along with simulations have been carried out to validate the effectiveness of the proposed self-localization technique.

Broadcast Secrecy via Key-Chain-Based Encryption in Single-Hop Wireless Sensor Networks

Broadcast is used in wireless sensor networks for operations such as software updates, network queries, and command dissemination. Applications such as battlefield control and natural resource management require not only authentication of broadcast messages, but also secrecy against eavesdroppers. In this paper we design, implement, and evaluate a novel scheme that meets the requirements of secrecy, authenticity, integrity, and freshness of broadcast messages in the context of a single-hop wireless sensor network. Our contributions are three-fold: first, we propose the use of time-varying keys (based on a key-chain) for broadcast encryption, emphasising advantages such as non-forgeability, protection against old-key compromise, and allowance for dynamic data. Second, we extend the basic key-chain mechanism to incorporate limited protection against key loss, allowing legitimate receivers to recover even if they have lost a small number of keys. Third, we prototype our scheme by incorporating it into Deluge, the network programming protocol distributed with TinyOS, and quantify its cost in terms of time, space, and power consumption on a TelosB mote platform. Our scheme represents a practical, efficient and scalable means of delivering broadcast data secretly to a large number of low-power sensor nodes.

Wireless Sensor Network Radio Power Management and Simulation Models~!2009-02-13~!2010-01-15~!2010-02-23~!

Wireless sensor networks (WSNs) create a new frontier in collecting and processing data from remote loca- tions. The IEEE 802.15.4 wireless personal area network-low rate (WPAN-LR) WSNs rely on hardware simplicity to make sensor field deployments both affordable and long-lasting without maintenance support. WSN designers strive to extend network lifetimes while meeting application-specific throughput and latency requirements. Effective power man- agement places sensor nodes (or motes) into one of the available energy-saving modes based upon the sleep period dura- tion and the current state of the radio. The newest generation of WPAN-LR-based sensor platform radios operates at a 250 kbps data rate and does not provide adequate time to completely power off the radio between the 128-byte constrained IEEE 802.15.4 transmissions. A new radio power management (RPM) algorithm presented in this paper exploits addi- tional energy-saving opportunities introduced with the new generation of faster platform transceivers. The RPM algorithm optimizes radio sleep capabilities by transitioning nodes to intermediate power level states. Additionally, this experimen- tal mote research also provides characterizations for the radio power levels, the mote platform state transition times, and the state transition energy costs of an IEEE 802.15.4 compliant sensor platform for improved accuracy in simulating WSN energy consumption.

Secure key loss recovery for network broadcast in single-hop wireless sensor networks

Symmetric encryption of data at the base-station using time-varying keys has been proposed as an attractive method for securing broadcasts in wireless sensor networks: symmetric decryption keeps computational costs at sensor nodes low, while time-varying group keys protect the network against key compromise at any of the receivers. However, a significant problem is that interference or disconnections may cause a receiver to miss broadcast packets and the dynamic keys contained therein, rendering it unable to participate in subsequent broadcasts. In this paper, we develop a scheme which allows receivers to recover from key loss in a secure, efficient, and scalable manner. Our scheme appends recovery information to each broadcast message to help out-of-sync receivers reattach probabilistically using an older key. We analyze our scheme to quantify the recovery probability as a function of system parameters, and deduce fundamental asymptotic bounds on recovery. We further prototype our scheme on the MicaZ mote platform and show that it is lightweight and efficient. Our solution offers a highly configurable, efficient and scalable method for key recovery in large sensor networks that require secure broadcasts.

Design and Implementation of a SecureWireless Mote-Based Medical Sensor Network

A medical sensor network can wirelessly monitor vital signs of humans, making it useful for long-term health care without sacrificing patient comfort and mobility. For such a network to be viable, its design must protect data privacy and authenticity given that medical data are highly sensitive. We identify the unique security challenges of such a sensor network and propose a set of resource-efficient mechanisms to address these challenges. Our solution includes (1) a novel two-tier scheme for verifying the authenticity of patient data, (2) a secure key agreement protocol to set up shared keys between sensor nodes and base stations, and (3) symmetric encryption/decryption for protecting data confidentiality and integrity. We have implemented the proposed mechanisms on a wireless mote platform, and our results confirm their feasibility.

An Energy Optimization Protocol Based on Cross-Layer for Wireless Sensor Networks

Survivability is one of the critical issues and the most important research topics in the fields of wireless sensor networks (WSNs). Energy efficiency is one of the determining factors for survivability and lifetime of WSNs. In the WSNs, severe energy issue necessitates energy-efficient approach to fulfill application objectives. In this paper, we propose an Energy Optimization Approach based on Cross-Layer for Wireless Sensor Networks named as EOA, which consider the joint optimal design of the physical, medium access control (MAC), and routing layer. The focus of EOA is on the computation of optimal transmission power, routing, and duty-cycle schedule that optimize the WSNs energy-efficiency. We first propose a feedback algorithm that computes the proper transmission power level between nodes. Then, routing protocol can make use of the transmission power as a metric by choosing route with optimal power consumption to forward packets. Finally, the cross-layer routing information is exploited to form a duty-cycle schedule in MAC layer. EOA is validated on a CROSSBOW’s MicaZ mote platform, and evaluated using the TOSSIM simulator, the simulation results show that EOA is an energy-efficient approach and able to achieve significant performance improvement as well.

Laser-scanning structural health monitoring with wireless sensor motes

A highly compact laser-scanning device that can be used as an in situ detection and monitoring device for metal fatigue is described. A prototype is built on a Mica2 wireless sensor mote platform with TinyOS-based firmware. This device is shown to be capable of detecting fatigue-related changes in the surface bidirectional reflectance distribution (BRDF) of an aluminum test coupon, and detectable changes in BRDF are measured at a very early stage of fatigue development, when no cracks larger than 50 µm in length have yet developed at the monitored location. The system power requirements are compatible with standard sensor mote architectures such as the Mica and Telos series, enabling the potential for multiyear lifetimes without battery replacement. Such an in situ optical fatigue sensor could be used in a variety of structural health monitoring applications, including aerospace, rail transport, and civil structures.

On the feasibility of high-power radios in sensor networks

Wireless sensor nodes are constrained by limited energy resources. A significant portion of this limited energy is spent in communication, making energy efficiency of the radio a very important factor in increasing the overall lifetime of a sensor node. An ideal radio, in terms of energy efficiency (ignoring issues of transmission range and delay), should satisfy two requirements. First, it should minimize the energy used per bit when transmitting or receiving. Second, its idle time energy consumption should be minimal. Unfortunately, no such "ideal" radio exists. Current sensor radios (e.g., CC2420) meet the second requirement - the energy consumption in the inactive states is very low in comparison to IEEE 802.11 radios, which are comparatively energy-inefficient due to high switching-on cost and idle state energy consumption. On the other hand, IEEE 802.11 radios perform much better when it comes to energy consumption per bit. So the natural question to ask is whether there exists a way to combine the positive features of these two types of radios leading to increased energy conservation. We argue that this objective can indeed be achieved by adding a high-power IEEE 802.11 radio to the mote platform alongside the already existing sensor radio and managing them by an energy-efficient scheme as proposed in this work.