Time synchronization in WSN Research Papers (original) (raw)

In the Distributed Systems (DS) the nodes are communicating with each other using message passing. Many real-time applications such as banking systems, reservation systems that are implemented on distributed systems, it is important to execute each transaction/event in an ordered manner. Ordering of events is essential for proper allocation of available resources and mutual allocation. This can be implemented using clock synchronization. The paper presents a comparative study of clock synchronization algorithms in distributed systems. The paper also discusses time protocol such as Network Time Protocol and Simple Network Time Protocol.

Time synchronization in wireless sensor networks is a critical requirement for distributed and collaborative processing among the nodes. This paper presents a coarse grained hierarchical time synchronization scheme ‘LevelSync’ which synchronizes nodes in a sensor network with regards to their distance from the sink or master node. A hierarchical tree is dynamically constructed during the synchronization with master node acting as the root. The master node initiates and controls the synchronization phase and is responsible for normalizing the virtual time with the corresponding UTC. Each node is assigned a level and maintains a virtual clock which runs at a frequency different than that of its physical clock. Virtual clocks run at a fixed frequency calculated by the root or reference nodes hence are free from the drifts. LevelSync decreases the number of messages required for the synchronization and the resynchronization periods. We evaluate the performance and energy efficiency of the LevelSync through simulation and compare with existing time synchronization protocols. LevelSync is computationally light, energy efficient and achieves long lasting synchronizations.

- by Dhyanendra S Rathore and +1
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- Time synchronization in WSN

In this paper, we apply adaptive control method to derive new results for the global chaos synchronization of 4-D chaotic systems, viz. identical Lorenz-Stenflo(LS) systems (Stenflo, 2001), identical Qi systems (Qi, Chen and Du, 2005) and non-identical LS and Qi systems. In this paper, we shall assume that the parameters of both master and slave systems are unknown and we devise adaptive control schemes for synchronization using the estimates of parameters for both master and slave systems. Our adaptive synchronization schemes derived in this paper are established using Lyapunov stability theory. Since the Lyapunov exponents are not required for these calculations, the adaptive control method is very effective and convenient to synchronize identical and non-identical LS and Qi systems. Numerical simulations are shown to demonstrate the effectiveness of the proposed adaptive synchronization schemes for the identical and non-identical, uncertain LS and Qi 4-D chaotic systems.

Time synchronization for wireless sensor networks (WSNs) has been studied in recent years as a
fundamental and significant research issue. Many applications based on these WSNs assume local clocks
at each sensor node that need to be synchronized to a common notion of time. Time synchronization in a
WSN is critical for accurate time stamping of events and fine-tuned coordination among the sensor nodes
to reduce power consumption. This paper proposes a bidirectional, reference based, tree structured time
synchronization service for WSNs along with network evaluation phase. This offers a push mechanism for
(i) accurate and (ii) low overhead for global time synchronization. Analysis study of proposed approach
shows that it is lightweight as the number of required broadcasting messages is constant in one
broadcasting domain.

- by Prof (Dr) Surendra Rahamatkar and +1
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- Wireless Sensor Networks, Broadcasting, Temperature Sensors, Clock synchronization

A significant challenge when implementing time synchronization protocols is minimizing timestamp uncertainties. The major problem of time synchronization is not only that this packet delay exists, but also being able to predict the time spent on each can be difficult. This paper aims to reduce these uncertainties by estimating them in the transmitter and receiver thus greatly increasing the performance of the time synchronization technique.

In this book we examined the implications of design space of Time Synchronization in Wireless Sensor Network and found that existing techniques are not adequate to provide appropriately support to some important regions in the design space. We suggested a new approach to fill this gap, by extending the existing time synchronization methods and combined in new ways in order to provide services that can meet the need of applications. We suggested an algorithm to be used by each sensor node to efficiently flood the network to construct a logical hierarchical structure from a designated source point then proposed a Tree Structured Referencing Time Synchronization (TSRT) scheme to minimize the complexity of the synchronization, which works in two phases. The proposed TSRT scheme is further extended for multi-hop Time Synchronization. We described comparison study of proposed scheme with similar existing synchronization protocols. In this we presented a survey and analysis of existing clock synchronization protocols with the suggested features of TSRT for wireless sensor networks.

- by Prof (Dr) Surendra Rahamatkar
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- Time synchronization in WSN

Time synchronization for wireless sensor networks (WSNs) has been studied in recent years as a fundamental and significant research issue. Many applications based on these WSNs assume local clocks at each sensor node that need to be synchronized to a common notion of time. Time synchronization in a WSN is critical for accurate time stamping of events and fine-tuned coordination among the sensor nodes to reduce power consumption. This paper proposes a bidirectional, reference based, tree structured time synchronization service for WSNs along with network evaluation phase. This offers a push mechanism for (i) accurate and (ii) low overhead for global time synchronization. Analysis study of proposed approach shows that it is lightweight as the number of required broadcasting messages is constant in one broadcasting domain.

- by AJAY AGARWAL
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- Computer Science, Cluster Computing, Broadcasting, Temperature Sensors

Time Synchronization aims towards synchronizing the local time for some or all nodes in the network is a necessity for many applications. Time synchronization help to find the computer clock difference and real time difference of transmission of message in wireless sensor network. We proposed a new technique based on time synchronization in wireless sensor network. This technique is derived by message exchange of level discovery phase in time synchronization protocol. We explain the basic level discovery phase technique to understand the time of data transmission in between sensor nodes and to make improvement in new and large area of sensor network.

- by Pooja Chaudhary
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- Computer Networks, Embedded Systems, Energy Conservation, Protocol Design

This work studies the dynamics, control and synchronization of hyperchaotic Lorenz-stenflo system and its application to secure communication. The proposed designed nonlinear feedback controller control and globally synchronizes two identical Lorenz-stenflo hyperchaotic systems evolving from different initial conditions with unknown parameters. Adaptive synchronization results were further applied to secure communication. The numerical simulation results were presented to verify the effectiveness of the designed nonlinear controller and its success in secure communication application.

Low power and limited processing are characteristics of nodes in Wireless sensor networks. Therefore, optimal
consumption of energy for WSN protocols seems essential. In a number of WSN applications, sensor nodes sense data
periodically from environment and transfer it to the sink. Because of limitation in energy and selection of best route,
for the purpose of increasing network remaining energy a node with most energy level will be used for transmission
of data. The most part of energy in nodes is wasted on radio transmission; thus decreasing number of transferred
packets in the network will result in increase in node and network lifetimes. In algorithms introduced for data
transmission in such networks up to now, a single route is used for data transmissions that results in decrease in
energy of nodes located on this route which in turn results in increasing of remaining energy. In this paper a new
method is proposed for selection of data transmission route that is able to solve this problem. This method is based
on learning automata that selects the route with regard to energy parameters and the distance to sink. In this method
energy of network nodes finishes rather simultaneously preventing break down of network into two separate parts.
This will result in increased lifetime. Simulation results show that this method has been very effective in increasing of
remaining energy and it increases network lifetime.

Sistem pendeteksi kendaraan di area parkir pada umumnya menggunakan metode konvensional, yaitu metode yangg menggunaan mikrokontroler sebagai control system, sensor sebagai komponen pengambil data dan kabel sebagai media pengiriman data. Pada umumnya sistem tersebut menggunakan satu mikrokontroler dalam mengolah data dari banyak sensor node secara bersamaan. Hal ini dapat menimbulkan masalah berupa data collision atau tabrakan data. Ketika data dikirimkan secara bersamaan, data dapat saling menginterferensi satu sama lain dan memungkinkan hilangnya informasi yang dikirimkan oleh masing-masing sensor node. Selain itu, penggunaan kabel sebagai media komunikasi data dianggap kurang efisien apabila diterapkan pada lingkup area yang luas jika dibandingkan dengan media komunikasi wireless yang praktis dan proses instalasi mudah. Untuk mencegah permasalah tersebut, pada penelitian ini diterapkan metode penjadwalan pengiriman data menggunakan protokol Time Division Multiple Access (TDMA) pada masing-masing node client. Diterapkan juga metode penyetaraan waktu Timing-synch Protocol for Sensor Network (TPSN) untuk menunjang metode penjadwalan. Pada penelitian ini juga menerapkan komunikasi data berbasis wireless dengan menggunakan modul wireless nRF24L01. Dari hasil implementasi, didapatkan hasil pengiriman data menggunakan protokol TDMA oleh masing-masing node client. Selain itu, node client dapat mengirimkan data sesuai jadwal yang telah didapatkan tanpa terjadi data collision. Pengiriman data tersebut telah berhasil dilakukan sesuai dengan slot waktu pengiriman yang telah diterapkan, dimana pada implementasinya slot waktu pengiriman dibagi menjadi 5 buah slot. Implementasi penyetaraan waktu juga telah berhasil diimplementasikan dengan rata-rata waktu dalam proses penyetaraan kurang dari 50 detik.

Time synchronization of nodes in WSNs is a challenging and ongoing problem. Several synchronization protocols for WSNs have been proposed recently over the years, addressing many issues such as synchronization accuracy, energy efficiency, message loss over the wireless channel and changes in the clock frequency due to environmental changes such as temperature. The variation in the supply voltage is one of the major contributing factors leading to clock drift between different sensor nodes. This paper presents an algorithm for the wireless sensor nodes clock drift compensation taking into account the supply voltage, which is measured by using a voltage divider circuit.

Wireless sensor networks (WSNs) have emerged as an attractive and key research area over the last decade. Time synchronization is a vital part of infrastructure for any distributed system. In embedded sensor networks, time synchronization is an essential service for correlating data among nodes and communication scheduling. This is realized by exchanging messages that are time stamped using the local clocks on the nodes. Various time synchronization protocols have been proposed aiming to attain high synchronization accuracy, high efficiency and low communication overhead. However, it requires that the time between resynchronization intervals to be as large as possible to obtain a system which is energy efficient having low communication overhead. This paper presents a simple but effective skew compensation algorithm that measures the skew rate of the sensor nodes with respect to the reference node and calibrates itself to compensate for the difference in the frequencies of the nodes. The proposed method can be incorporated with any existing time synchronization protocol for WSNs.

- by Shiu Kumar
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- Embedded Systems, Wireless Sensor Networks, Time synchronization in WSN

The metrology field has been progressed with the appearance of the wireless intelligent sensor systems providing more capabilities such as signal processing, remote multi-sensing fusion etc. This kind of devices is rapidly making their way into medical and industrial monitoring, collision avoidance, traffic control, automotive and others applications. However, numerous design challenges for wireless intelligent sensors systems are imposed to overcome the physical limitations in data traffic, such as system noise, real time communication, signal attenuation, response dynamics, power consumption, and effective conversion rates etc, especially for applications requiring specific performances. This paper analyzes the performance metrics of the mentioned sensing devices systems which stands for superior measurement, more accuracy and reliability. Study findings prescribe researchers, developers/ engineers and users to realizing an optimal sensing motes design strategy that offers operati...

Time synchronization for wireless sensor networks (WSNs) has been studied in recent years as a fundamental and significant research issue. Many applications based on these WSNs assume local clocks at each sensor node that need to be synchronized to a common notion of time. Time synchronization in a WSN is critical for accurate time stamping of events and fine-tuned coordination among the sensor nodes to reduce power consumption. This paper proposes a bidirectional, reference based, tree structured time synchronization service for WSNs along with network evaluation phase. This offers a push mechanism for (i) accurate and (ii) low overhead for global time synchronization. Analysis study of proposed approach shows that it is lightweight as the number of required broadcasting messages is constant in one broadcasting domain.

- by AJAY AGARWAL
- •
- Wireless Sensor Networks, Cluster Computing, Broadcasting, Temperature Sensors