Ahmed Ayadi

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Low-power and Lossy Networks (LLNs), like wireless networks based upon the IEEE 802.15.4 standard, have strong energy constraints, and are moreover subject to frequent transmission errors, not only due to congestion but also to collisions and to radio channel conditions. This paper introduces an analytical model to compute the total energy consumption in an(More)
New wireless sensor network applications (e.g., military surveillance) require higher reliability than a simple best effort service could provide. Classical reliable transport protocols like Transmission Control Protocol (TCP) are not well suited for wireless sensor networks due to both the characteristics of the network nodes (low computing power, strong(More)
The 6LoWPAN layer was recently introduced as a means to enable the transmission of IPv6 datagrams over Low-power and Lossy Networks (LLNs). That layer provides schemes for fragmenting the network-layer datagrams and reassembling link-layer fragments. However, the loss of one fragment of the original datagram will lead to the loss of the latter, and(More)
In vision-based medical applications involving tools attached to a robotic arm, it is essential to be able to accurately localize these tools in the robot end-effector frame. Indeed, inaccurate tool-calibration has a direct impact on the accuracy of the task. In this paper, we introduce a versatile and robust calibration technique to estimate the relative(More)
The development of new medical therapies often require experiments on small animals. In order to improve the medical protocol during treatments with needles, we propose a new robotic needle insertion system using CT-scan imaging and visual servoing. The biologist defines the skin entry point and the target to be reached in the CT-image. The needle target is(More)
Reliable transport protocols like TCP are in principle not well suited for wireless sensor networks (WSNs), due to both the characteristics of the network nodes (low computing power, strong energy constraints) and those of the typical applications running on such nodes (low data rates). Indeed, TCP has not been designed with energy efficiency in mind, and(More)
Transmission Control Protocol (TCP) was considered unsuitable for Low power and Lossy Networks (LLNs) due to the characteristics LLN devices (low computing power, strong energy constraint, etc.) and to the absence of IP layer on the network layer. Recently, the IPv6 over Low power Wireless Personal Area Networks (6LoWPANs) has been introduced as an(More)
This paper presents an experimental study of TCPHC, a novel algorithm for compressing the Transmission Control Protocol (TCP) header to reduce its overhead in IPv6-enabled Low-power and Lossy Networks (6LoWPANs). Results show that TCPHC outperforms TCP both in low-loss and high-loss networks. In fact, TCPHC can reduce the TCP header to 6 bytes in more than(More)
Recently, Wireless Sensor Networks (WSN) became one of the most important areas of research in the world. The Quality of Services (QoS) is the cornerstone of WSN efficiency due to providing the network with all requirements for efficient sending and receiving of data. Because of WSN different infrastructures, there are different QoS parameters required for(More)