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This paper proposes a Delay Asymmetry Correction (DAC) Model to enhance clock synchronization protocols based on a Master-Slave arrangement such as the IEEE 1588 PTP protocol. The purpose of this work is to mitigate the effects of unpredictable packet delay variations (PDV), which may aggravate asymmetric link delays on timing packets, in order to improve the synchronization accuracy of the slave...
Congestion control mechanisms include three phases: congestion detection, congestion notification and rate adjustment. So far diverse congestion detection methods for sensor networks are proposed. In this paper we introduce numerous congestion detection parameters and examine them in various respects; finally we choose one of them as the best parameter for video traffic in wireless sensor networks...
One-way delay (OWD) is an important measurand for network management. It can indicate routing problems, network congestion, and is useful for tracking down application problems to network effects. While active measurements deliver high accuracy, measuring OWD actively on all paths of large networks results in high effort. Thus, passive measurements are attractive. Our approach for measuring OWD is...
Duty cycling is often used to reduce the energy consumption caused by idle listening in Wireless Sensor Networks (WSNs). Most studies on WSN protocols define a common duty cycle value throughout the network to achieve synchronization among the nodes. On the other hand, a few studies propose adaptation of the duty cycle according to uniform traffic conditions, which is beneficial assuming one-to-one...
Several underwater network characteristics, including long propagation delays and a bandwidth dependent on distance, provide unique challenges to protocol designers. In this paper we present STUMP-WR, a distributed routing and channel scheduling protocol, designed for heavily loaded underwater networks. STUMP-WR selects and schedules links using a distributed algorithm to overlap communications by...
In this paper we investigate the ratio of dwelling time in control channel (CCH) and service channel (SCH) for single channel devices deploying WAVE (Wireless Access in Vehicular Environments) protocols. Based on analytical model for both channels and four traffic types we present tradeoffs in channel performance when CCH/SCH duty cycle is changing. Our results show that, when video traffic is absent,...
A crucial aspect of mission-critical vehicles is their reaction to environmental or system-internal changes. Ideally, the new situation is autonomously assessed and the vehicle's behavior is adapted accordingly. Modern mission-critical vehicles realize a network-centric design approach, for one reason because it follows the inherent requirements of interconnecting the sensors and actuators of a control...
The development of network convergence and multimedia service are driving the management of heterogeneous devices. According to the disadvantages of the existing device management mechanisms, a converged protocol for the management of heterogeneous devices is proposed to facilitate the convergence of service. Following the top-down model, the converged device management protocol (CDMP) is designed...
Network-assisted diversity multiple access (NDMA) was recently developed to resolve collision and achieve high throughput. The blind NDMA method using independent component analysis (ICA), named ICA-NDMA, has been shown to overcome the difficulties of synchronization and orthogonal identification codes required by the training-based NDMA protocols. In this paper, we propose a novel blind collision...
In this paper we address the Quality of Service (QoS) issues for applications such as voice and video that generate bursty traffic in mobile ad hoc networks while asynchronous power saving protocols are applied to wireless hosts. To provide QoS, we propose our new quorum-based power saving protocol called "consecutive quorum-based power saving (CQPS)". Within this torus-based protocol each...
Combining wireless sensor networks (WSNs) with delay-tolerant networking (DTN) has the potential to extend their use in a multitude of previously impossible applications. However, and despite numerous proposed solutions, there is still wide debate as to how to best route messages in these networks and, more importantly, how to do it in an energy-efficient way. This paper proposes CHARON (Convergent...
Wireless communications in the industrial automation world still suffer from lack of standardization. WirelessHART, released in September 2007, is still the only open communication standard specifically designed for real-time process control applications. This paper presents an innovative distributed tool for capturing WirelessHART packets in the field. In fact, even if tools for compliance assessment...
Botnets with the centralized architecture provide a simple, low-latency, anonymous and efficient real-time communication platform for the botnet controllers. To our knowledge, most of the latest detected large-scale botnets are based on the centralized structure with HTTP or customized protocols. Therefore, centralized botnets detection helps greatly improve control of unwanted traffic. The main contribution...
Medium access control (MAC) protocols play a crucial role in energy-efficiency, latency reduction for sensor networks. Many research efforts have been made to reduce energy consumption and shorten delay in multi-hop WSNs. Although some existing MAC protocols are energy-efficient and are able to mitigate the end-to-end delivery latency, there are great potential for further improvements. In this paper,...
Time synchronization of wireless sensor network (WSN) nodes is essential to schedule orderly communication and monitoring tasks. In this paper, a synchronization algorithm based on linear control theory is used to compensate at run-time both time offsets and clock frequency skews. The proposed approach is innovative for two reasons. First of all, the controller correcting the local timers is able...
Peer-to-peer (P2P) systems, which are realized as overlays on top of the underlying Internet routing architecture, contribute a significant portion of today's Internet traffic. They have recently absorbed a lot of attention from the Internet users and the research community. Regarding the difficulty and cost for a large scale living deployment, many proposed P2P protocols were evaluated by a simulator...
This paper focuses on feasibility of the time-triggered IEEE 802.15.4 protocol to satisfy the network-based control systems(NCS) performance. The IEEE 802.15.4 protocol is considered to be unsuitable for industrial networks because its medium access control method is contention-based CSMA/CA, which exhibits unstable performance with an unbounded delay distribution under heavy traffic. To avoid these...
A novel concept for robust and precise clock synchronization in wireless networks is introduced. The concept is based on a Kalman filter that is parallelly distributed on all network nodes. Each node uses the state estimates of other nodes to determine a local estimate of the global clock. A voting algorithm that evaluates the state estimates of several nodes is used to adjust the virtual global clock...
We experimentally investigate data protocol transparent 3times43 Gb/s to 129 Gb/s WDM-to-OTDM conversion based on an asynchronous retiming scheme, for buffer-less OTDM traffic grooming. We demonstrate worst-case power penalty of less than 3.5 dB.
Extending system lifespan by managing power on mobile nodes is critical and primordial in wireless ad hoc networks. Recent work has shown that, by appropriately powering off nodes, energy may be significantly saved, especially when node density is high. Such approaches rely on the selection of a virtual backbone of the topology to forward ongoing traffic, coupled with functions to reorganize (manually...
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