showing 15 related works from this author
Performance of H.264 compressed video streams over 802.11b based MANETs
2004
We address the problem of video streams transmission in 802.11b based mobile ad-hoc networks (MANETs). Through the study of the delivery of a live encoded video stream, we expose the characteristics of different routing protocols and the infeasibility to provide QoS. The analysis shows the impact of a MANET on H.264 real-time video flows in terms of packet loss, end-to-end delay, jitter and distortion, and the behavior of H.264 error resilience tools in order to determine their effectiveness on such network scenarios. The results show that video traffic has demands that are hard to be met by a standard MANET, and that improvements are required in terms of routing protocols and QoS provision…
A MANET Autoconfiguration System based on Bluetooth Technology
2006
The availability of both Wi-Fi and Bluetooth technologies on currently available devices offers the possibility to combine both in order to make the most out of their capabilities. In this paper we propose using Bluetooth technology to solve the configuration problem of the terminals conforming an IEEE 802.11-based ad-hoc network. The main objective of mobile ad- hoc networks (MANETs) is to extend the connectivity range of nodes through packet forwarding, thereby avoiding the use of a fixed infrastructure. However, since configuration of nodes is a complex issue, we provide a fast and reliable solution to auto-configure MANET terminals. Our solution is adequate for the quick setup and deplo…
A New FEC Scheme for Real-time Transmission of High Definition Video over IP Network
2007
Increasing the applicability of ubiquitous computing, minimizing energy consumption and hardware cost are mandatory in real world applications. In this paper we present our platform prototype for ubiquitous computing, which has been implemented based on commercial Bluetooth off-the-shelf components. It allows every object to be augmented with processing and communication capabilities in order to make them "smart". We validate our proposal by evaluating the trade-off between power consumption and performance of the experimental prototype.
A low-cost embedded IDS to monitor and prevent Man-in-the-Middle attacks on wired LAN environments
2007
A man-in-the-middle (MitM) attack is, in the scope of a LAN, a technique where an attacker is able to redirect all traffic between two hosts of that same LAN for packet sniffing or data manipulation, without the end hosts being aware of it. Usually these attacks exploit security flaws in the implementation of the ARP protocol at hosts. Up to now, detecting such attacks required setting up a machine with special-purpose software for this task. As an additional problem, few intrusion detection systems (IDS) are able to prevent MitM attacks. In this work we present a low-cost embedded IDS which, when plugged into a switch or hub, is able to detect and/or prevent MitM attacks automatically and …
Assessing the effectiveness of IEEE 802.11e in multi-hop mobile network environments
2004
The IEEE 802.11e technology is receiving much interest due to the promising enhancements it offers to wireless local area networks in terms of QoS support. Until now, research has focused on single hop, access point based environments, which are the most common. We review the enhancements proposed in the last IEEE 802.11e draft (version 8.0). We analyze the performance of the IEEE 802.11e protocol on ad-hoc networks (multi-hop) in terms of throughput and end-to-end delay. We also measure the effectiveness for static and fully dynamic networks with a variable number of source stations. Finally, we analyze the performance of IEEE 802.11e when legacy IEEE 802.11 stations (no IEEE 802.11e suppo…
Supporting scalable video transmission in MANETs through distributed admission control mechanisms
2009
Emerging multimedia applications over mobile devices are becoming very popular, especially over infrastructure wireless networks such as cellular and WLANs. However, providing this kind of services over infrastructureless networks like ad hoc networks presents many additional problems. One of these problems is how to share resources fairly among the users involved. In this article we propose a QoS framework supporting scalable video streaming in mobile ad hoc networks based on distributed admission control and video traffic awareness. Our framework promotes fairness between video flows in terms of resource consumption. It also guarantees a significant reduction of the idle times experienced…
On the Interaction Between IEEE 802.11e and Routing Protocols in Mobile Ad-Hoc Networks
2005
The upcoming IEEE 802.11e standard was developed to offer QoS capabilities to WLAN, offering significative improvements to multimedia traffic. MANETs also benefit from this new technology since the most widely deployed and used wireless interfaces are IEEE 802.11 based. In this paper we expose results relative to the interaction of reactive routing protocols for MANETs and the IEEE 802.11e technology. We find that very substantial improvements in terms of throughput and normalized routing overhead are achieved due to increased routing responsiveness. We also detail the relation between the behavior experienced in each case and the internal mechanisms of the routing protocol being used, offe…
Evaluating the Performance of Real Time Videoconferencing in Ad Hoc Networks Through Emulation
2008
The validation of new video protocols and applications for mobile ad hoc networks in a real environment is an important task. In this work we present Castadiva, a test-bed architecture that allows validating software solutions for ad hoc networks using low-cost, off-the-shelf devices and open source software. We use this tool to test a videocall using the OLSR protocol in different scenarios, varying the number of hops between the caller and the receiver. The results obtained in this paper show that, for an ad hoc network with a large number of hops, the quality of videocalls suffers a significant degradation even in the absence of mobility.
Modeling of mobility and groups in inter-vehicular MANET-based networks
2007
This paper evaluates the behavior of mobile ad hoc networks when group mobility is involved. We concentrate on group mobility because road vehicles tend to form groups or fleets whose behavior depends on the behavior of the close-by vehicles. We propose four different group mobility models and present a mobility pattern generator, called grcmob that we designed to be used with the ns-2 simulator. We evaluate the performance of vehicular ad hoc networks under a wide number of scenarios using both TCP and UDP data traffic. We show that the number of groups is more important than the number of nodes and that the impact of area size is almost negligible. We also reveal that the mixture of inter…
A Wireless Mesh Network-based System for Hotspots Deployment and Management
2007
In recent years Wireless Local Area Networks (WLANs) or hotspots, as they are commonly known, have emerged as a promising networking platform to extend network connectivity in public venues, providing local coverage for Internet applications on the move in urban areas and rural environments. Wireless hotspots using 802.11-based technology have popped up in corporate offices, coffeehouses, airports, restaurants and bookstores worldwide. For all their utility and ease of use the 802.11 wireless protocol, known as WiFi, has become the mobile connectivity mechanism of choice for business people, travelers, villagers, and everyone else. Unfortunately, even with the protocol's ease of use and its…
Castadiva: A Test-Bed Architecture for Mobile AD HOC Networks
2007
Evaluating and deploying all sorts of protocols and applications designed for wireless ad hoc networks in a real environment is an important and urgent task. Traditionally, all the proposals made rely solely on simulator results. However, as different research groups develop different solutions to solve problems related to these new networks, it becomes more and more important to migrate the proposed solutions to a real environment. In this work we present Castadiva, a test-bed architecture that allows validating software solutions for ad hoc networks using low-cost, of the-shelf devices and open source software. Through a friendly user interface, Castadiva offers the possibility to define …
Evaluation of the Impact of Multipath Data Dispersion for Anonymous TCP Connections
2007
Despite recent research efforts, wireless ad hoc networking technology remains especially prone to security attacks. In this work our contribution focuses on determining the optimal trade-off between traffic dispersion and TCP performance to reduce the chances of successful eavesdropping, while maintaining acceptable levels of throughput. For our experiments we propose a multipath-enhanced version of DSR, and we compare Tahoe, Reno and Sack TCP variants. Results show that multipath traffic dispersion impact on TCP throughput is bounded to a maximum of 25-35%, and that there is only a minimal dependence on the number of routes used, the number of consecutive packets sent on each route, the r…
Building a research prototype to provide pervasive services in hospitals
2008
Research into the nature of pervasive computing has now been around for more than a decade. Nowadays pervasive applications exploit mobile wireless communication technologies to interconnect computing devices along with various sensing technologies, setting up a new kind of intelligent environment where applications can transparently search and use services without userspsila intervention. However, there are few examples of real world deployment of pervasive computing moving out from academic laboratories into our everyday life. We present BlueHospital - a research prototype that provides context-aware information and location based services to clinicians in hospitalspsila recovery wards. T…
A flexible and tunable route discovery mechanism for on-demand protocols
2004
Mobile ad-hoc networks are characterized by multihop wireless links and absence of cellular infrastructure. For the last years, routing has been the area under most intensive research. In particular, on-demand routing protocols proposed are extremely attractive due to their low-overhead and efficiency. Currently, wireless ad-hoc networks lack multipath routing protocols. Multipath routing enables increased QoS support, load balancing and enhanced route stability. In this paper we present a new route discovery solution that increases the number of routes found, while reducing the routing overhead when compared to previous proposals. Simulation results show that the additional routing overhea…
Multipath extensions to the DYMO routing protocol
2007
Multipath routing is a technique that can improve performance, specially in mobile ad hoc networks. Due to traffic dispersion it can perform load balancing; minimize the energy consumed by nodes or prevent traffic analysis. In this work we focus on enhancing the DYMO protocol to support multipath routing. We study the impact of traffic dispersion on both UDP and TCP traffic when varying a set of parameters.