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Distributed beamforming technique has been introduced in the wireless sensor network (WANs) in order to increase the transmission range and signal strength of sensor node. The identical data is transmitted to the destination by all nodes which have timing and carrier synchronously. Then, the data transmissions are combined gainfully at the destination. Thus accuracy of reference signal for synchronization...
Heterogeneous networks have the potential to improve coverage, throughput, and energy efficiency of wireless networks through the use of specialized cellular structures, in particular femtocells and macrocells. However, to reduce interference between different cells, ensure smooth hand-offs from cell to cell, and achieve seamless operation the overall network needs to be synchronized. In this paper...
Time synchronization plays a critical role in distributed network systems. In this paper, we investigate the time synchronization problem in the context of underwater sensor networks (UWSNs). We propose a pairwise, cross-layer, time synchronization scheme for mobile underwater sensor networks, called TSMU. Facilitated by the Kalman Filter, the proposed method greatly improves the dynamic propagation...
BitTorrent(BT) has emerged as one of the most popular protocols for content sharing in recent years. Most BT applications are network-oblivious which brings great challenges to traffic engineering. As basic input information, network-wide BT traffic distribution is of vital importance for service providers (SP) or carriers to enforce appropriate control policies. Direct online measurement of network-wide...
This paper proposes a preamble detection-based cooperative transmit time pre-synchronization technique specially for Concurrent Cooperative Transmission (CCT). CCT enables a collection of power-constrained radios to transmit as a group and achieve a transmit range that is much greater than the range of a single device. In the absence of a GPS system or a globally synchronized clock, each cooperating...
With the advance of computer and communication technologies, wireless sensor networks (WSNs) are increasingly used in many aspects of our daily life. However, since the battery lifetime of WSN nodes is restricted, the WSN lifetime is also limited. Therefore, it is crucial to determine this limited lifetime in advance for preventing service interruptions in critical applications. This paper proposes...
Underwater acoustic sensor networks are quite different from terrestrial wireless sensor networks. Localization for underwater applications is different due to the bandwidth limited acoustic communication, sparsely distributed network deployment, and more expensive and powerful sensor nodes. In this paper, we propose a new scheme to achieve better localization accuracy for underwater acoustic sensor...
The peer-to-peer (P2P) network paradigm has been introduced in order to overcome some shortcomings of the client-server architecture by providing such features as decentralization, self-organization, scalability, and fault-tolerance. Bootstrapping is the initial process through which new nodes can join an existing P2P overlay network. Typically, a joining peer must first contact a bootstrap peer,...
This paper presents PariSync, a distributed system for clock synchronization in DHT-based peer to peer networks. PariSync is formed by two modules: a topology module, that chooses for each node a small subset of neighbors with which to exchange timing information (piggybacking on the DHT link structure) and an extimation module, that assembles the information into an extimate of the node's offset...
Monitoring of industrial and community environments and infrastructures are increasing targets for wireless sensor network (WSN) applications. Such applications are distributed by their nature and require essentially timing synchronization and location awareness of the sensor nodes. In this paper we present a WSN platform suitable for environment and condition monitoring applications. Time synchronization...
Multiple antenna systems have been shown to provide significant performance improvements for network nodes; however, the vast majority of nodes in military networks will be limited to single channel devices due to mobility (size and power) and ease of use considerations. In this paper we apply a new joint synchronization-pilot sequence (JSPS) optimization design technique to multiple transmitter OFDM...
The duty cycle of a wireless sensor node is a key factor that determines the life time of a wireless sensor network. In general, sensor medium access control protocols reduce the duty cycle to achieve longer lifetime. However, we found out that their performance improvements substantially decrease under extremely low duty cycles (<0.1%). Our proposed W-MAC protocol targets achieving low energy...
Direct application of network coding at the physical layer - physical layer network coding (PNC) - is a promising technique for two-way relay wireless networks. In a two-way relay network, relay nodes are used to relay two-way information flows between pairs of end nodes. This paper proposes a precise definition for PNC. Specifically, in PNC, a relay node does not decode the source information from...
Sensor nodes are small-size, low-cost embedded systems capable of local processing and RF communication. In a sensor network, nodes need to organize their operations to perform distributed sensing tasks, and need therefore to be time synchronized to a common reference. In this paper we present a time-synchronization approach for wireless sensor networks(WSNs), denoted as accuracy-driven synchronization...
In multihop wireless sensor networks, global clock error will accumulate as the hops grow. Sensors far away from the root are likely to suffer larger synchronization errors, which may deteriorate the accuracy of sensing data or even result in the failure of TDMA MAC protocols. A novel algorithm based on vector Kalman filter using multiple parents (KFMP) is proposed to address this problem. It's pointed...
Previous works in P2P streaming provide many kinds of solutions to construct an effective streaming overlay, they either lack of flexibility or can not gain global optimal performance. A new synchronization based approach proposed in this paper use a fully distributed scheme to achieve optimal peer selection and dynamic peer management. Especially, the working set discrepancy between peers is taken...
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