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This paper aims at presenting an experimented low power Internet of Things architecture, that could be integrated to underwater monitoring systems like Autonomous Underwater Vehicles for wireless underwater sensing. The proposed hardware architecture of the sensor nodes is based on an ultra-low-power Flash Micro-controller that takes measurements from water sensors, and synchronizes the network by...
We developed a field management system with a field server that helps decrease farmers workload. It will be also enable the transfer of knowledge to the next generation of farmers in Japan. In order to reduce the burden of agricultural work, less frequent maintenance of the field server is desired. In this paper, we explain construction method of a local wireless network to cut the power consumption...
This paper provides a methodology to study the PHY layer vulnerability of wireless protocols in hostile radio environments. Our approach is based on testing the vulnerabilities of a system by analyzing the individual subsystems. By targeting an individual subsystem or a combination of subsystems at a time, we can infer the weakest part and revise it to improve the overall system performance. We apply...
We propose and experimentally demonstrate a downlink 60-GHz millimeter-wave radio-over-fiber fronthaul incorporating coordinated multipoint (CoMP) transmission scheme. CoMP function is implemented in the centralized baseband unit to obtain the transmission diversity. Space-time diversity gain is exploited to improve the data rate of cell-edge users as well as the coverage of 60-GHz small cells. To...
This paper describes a distributed wireless acoustic sensor network (WASN) platform called WHISPER that is capable of synchronous multichannel sampling at different spatial locations with a sampling clock whose relative jitter is less than 300 ns. The platform comprises up to four data acquisition modules with onboard computing capabilities, and that can form an ad-hoc Wi-Fi network allowing an additional...
Dense Wi-Fi and Bluetooth (BT) environments become increasingly common so that the coexistence issue between Wi-Fi and BT is imperative to solve. In this paper, we propose BlueCoDE, a coordination scheme for multiple neighboring BT piconets, to make them collision-free and less harmful to Wi-Fi. BlueCoDE reuses BT's existing PHY and MAC design, thus making it practically feasible. We implement a prototype...
Machine-to-machine (M2M) communication is an up-and-coming technology for Internet of Things. However, current wireless cellular network such as LTE-A that is originally designed for human-to-human (H2H) communication falls short in supporting massive number of bursty random access (RA) requests from machine type communication (MTC) devices. Specifically, random access network (RAN) overload due to...
Time synchronization, aiming to provide a common timescale among distributed sensor nodes, is a key enabling technology for many applications, such as collaborative condition monitoring and localization detection. Due to the complexity of time synchronization in wireless sensor networks, the Discrete Event Simulator is recommended to adopt resulting from the feature that the behavior of a complex...
With the continuous progress of rural construction, the problem of rural drinking water pollution is increasingly prominent. In view of water pollution, a design of rural drinking water monitoring system based on wireless sensor networks is proposed that nodes take STM32 as the core chip and WLK01L39 as well as its peripheral circuits are used as wireless communication modules and Beidou S1216 is...
This paper investigates a high power factor switch-based wireless power transfer front-end circuit for heterogeneous systems. This circuit uses an integrated switching rectifier, implemented in 0.18um 1.8V/5V CMOS process. An integrated pair of phase synchronizers is used to align the waveshape of a wirelessly-coupled sinusoidal voltage source in the receiving coil to the corresponding conducting...
Precision time synchronization is critical for distributed sensing, and coordinated actuation in various low-range wireless applications in Internet of Things and Robotics. The state-of-the-art time synchronization protocol however, known as Precision Time Protocol (PTP) is designed for wired networks. In this work, we make an effort to enable PTP for Low Range Wireless Personal Area Networks (LR-WPAN)...
An electric network frequency (ENF) signal can be found in multimedia recordings due to propagation from the power grid. There a variety of applications based on ENF signal use, such as video and audio stream synchronization, and origin determination of multimedia recordings. In this paper, we propose the use of ENF to synchronize real-time audio streams from different, non-synchronized sound devices,...
As wireless sensor networks become more ubiquitous in the world, the need for lightweight, resilient time synchronization protocols is apparent. Wireless nodes' internal clocks are subject to drift over time due to manufacturing imperfections and environmental changes. While various protocols have been introduced that attempt to correct for this drift, they each have their own peculiarities and issues...
IEEE 802.15.4e network aims at providing highly reliable communication links via time slotted channel hopping (TSCH) technology for lossy wireless channels. In such network, all nodes remain synchronized via message exchange periodically to compensate for the clock drift. In this paper, we derive theoretical average time for a node to remain in synchronized status with its parent node under the noisy...
Water management is an important issue in economics and environment. Recently, amount of water control system has been proposed and developed. For the type of intelligent water control, the related parameters will be the input of the control system. Hence, there is a need of developing a scalable, flexible and reliable sensor network for related parameters monitoring. To install and replace water...
We consider a collision channel model without feedback based on a time-slotted communication channel shared by K users. In this model, packets transmitted in the same time slot collide with each other and are unrecoverable. Each user accesses the channel according to an internal periodical pattern called protocol sequence. Due to the lack of feedback, users cannot synchronize their protocol sequences,...
The continuous fluctuation of electric network frequency (ENF) presents a fingerprint indicative of time, which we call natural timestamp. This paper studies the time accuracy of these natural timestamps obtained from powerline electromagnetic radiation (EMR), which is mainly excited by powerline voltage oscillations at the rate of the ENF. However, since the EMR signal is often weak and noisy, extracting...
This paper studies a system where a set of relay nodes harvest energy from the signal received from a source to later utilize it when forwarding the source's data to a destination node via distributed beamforming. To this end, we derive (approximate) analytical expressions for the mean SNR at destination node when relays employ: i) time-switching based energy harvesting policy, ii) power- splitting...
In this paper we present methods to reach 10-years of battery life for Industrial Internet of Things (IIoT) wireless sensor network (WSN) using a platform called the I3Mote. I3Mote provides connected sensor nodes for tough industrial environment and a number of I3Motes can form a large-scale coverage of data collectors or actuators. The goal is to achieve 10-years network life time for all the connected...
Several communication protocols based on channel hopping have been proposed for wireless sensor networks. One prominent example is IEEE 802.15.4e, which relies on the concept of time-slotted channel hopping (TSCH). TSCH effectively mitigates poor channel conditions (caused, e.g., by fading) by means of channel changes according to a pre-defined hopping sequence. In order for nodes to participate in...
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