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We consider the clock synchronization problem in wireless mobile ad hoc networks in the presence of Byzantine nodes. The communication topology is dynamic: nodes move randomly within a geographical area. We propose a clock synchronization protocol which is based on the linear approximate consensus method. Periodically each correct node broadcasts its current timestamp and gathers the timestamps provided...
In order to decrease the complexity of popular distributed slot synchronization algorithms for adhoc networks, a new method using average weighting is proposed based on Vicsek model, which is basic model of multi-agent systems. The slot starting time of each node is updated by using a simple local rule based on the average of its own slot starting time plus neighbors. Finally, all nodes have the same...
This paper presents Nest, a novel system using wirelessly connected smartphones to localize remote targets based on sound and image inputs. The system has four major components: image-based localization, acoustics-based localization, wireless ad-hoc networking, and middle-ware services for time synchronization and secure communication. Single-image, two-image, and TDOA-acoustics based methods have...
In this paper, a fully distributed synchronization scheme for wide-range TDMA Ad-Hoc networks is described. This synchronization scheme provides a simple algorithm with low overhead requirements to achieve high clock synchronization accuracy in a fully distributed approach. Our work is based on the clock sampling mutual network synchronization (CS-MNS) algorithm. It extends it by including the propagation...
In the past various protocols inspired by nature and biology have been proposed to disseminate or transfer data in mobile or static ad-hoc networks. Many of them are designed for usage in wireless sensor networks or vehicular ad-hoc networks. Recently, we have developed and designed a general purpose data dissemination protocol called AutoCast in this field that we evaluated in detail by simulations...
As one of the key technologies in Ad hoc networks, clock synchronization is the prerequisite of important network functions. Main consideration in clock synchronization are the choice of global clock and the accuracy, in which the existing clock synchronization methods still suffer lack. In this paper, the network delay is measured in networking process, and the network nodes complete synchronization...
Utilizing service oriented architectures to enhance seamless collaborations and information sharing among nodes in mobile ad hoc networks with limited communication capability is a challenging task. In this paper a novel tree-based service discovery mechanism, able to achieve high accuracy in the process of service discovery, is proposed, which affords wireless communication overheads nearly linear...
In mobile ad hoc networks (MANETs), time synchronization can be achieved by distributing time information among nodes. This type of time synchronization, however, does not work well under considerable long delay caused by sparse population. In this paper, we propose a simple yet effective scheme for relative time synchronization. When two mobile nodes meet, they exchange their clock information and...
Wormhole attacks in mobile ad hoc networks (MANET) have long been considered a serious threat to MANET's routing. Most of the existing proposals rely on GPS devices and require that the node's clocks are synchronized. Such constraints naturally lead to limitations of applicability since GPS does not operate well in obstructed areas, and clock synchronization in MANET is not always accurate. In this...
In this paper, we present black burst synchronization (BBS), a novel protocol for decentralized network-wide tick synchronization in wireless ad hoc networks, located at MAC level. We argue that tick synchronization is sufficient for multi- hop medium slotting, and that it can be used as a basis for time synchronization. BBS is based on the exchange of synchronized tick frames, which are protected...
We propose QUEST (QUality ESTimation), a new method that accurately estimates IEEE 802.11 wireless link quality with no in-band signaling overhead. Existing link quality estimation methods either are based on hello exchanges by fixing or varying transmission rates or rely on the history (e.g., delivery ratio) of previously sent data packets in a per-rate/-neighbor manner. QUEST on the other hand,...
IEEE 1588 is a new standard to synchronize independent clocks running on separate nodes of a distributed measurement and control system. It is intended for high-accuracy implementations on compact systems such as a single subnet. This paper examines potential accuracy limitations introduced by the physical layer of the IEEE 802.11b wireless local area network. Experimental results are presented that...
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