[show abstract][hide abstract] ABSTRACT: The increasing popularity of network-based multimedia applications poses many challenges for content providers to supply efficient and scalable services. Peer-to-peer (P2P) systems have been shown to be a promising approach to provide large-scale video services over the Internet since, by nature, these systems show high scalability and robustness. In this paper, we propose and analyze an object management policy approach for video web cache in a P2P context, taking advantage of object's metadata, for example, video popularity, and object's encoding techniques, for example, scalable video coding (SVC). We carry out trace-driven simulations so as to evaluate the performance of our approach and compare it against traditional object management policy approaches. In addition, we study as well the impact of churn on our approach and on other object management policies that implement different caching strategies. A YouTube video collection which records over 1.6 million video's log was used in our experimental studies. The experiment results have showed that our proposed approach can improve the performance of the cache substantially. Moreover, we have found that neither the simply enlargement of peers' storage capacity nor a zero replicating strategy is effective actions to improve performance of an object management policy.
International Journal of Digital Multimedia Broadcasting 01/2012; 2012.
[show abstract][hide abstract] ABSTRACT: In this paper, we propose a newly distributed protocol called Advanced Diffusion of Classified Data (ADCD) to manage information harvesting and distribution in vehicular sensor networks. ADCD aims at reducing the generated overhead, avoiding network congestions as well as long latency to deliver the harvested information. The concept of ADCD is based on the characterization of sensed information (i.e., based on its importance, location, and time of collection) and the diffusion of this information accordingly. Furthermore, ADCD uses an adaptive broadcasting strategy to avoid overwhelming users with messages in which they have no interest. Also, we propose in this paper a new probabilistic model for ADCD based on Markov chain. This one aims to optimally tune the parameters of ADCD, such as the optimal number of broadcaster nodes. The analytical and simulation results based on different metrics, such as the overhead, the delivery ratio, the probability of a complete transmission, and the minimal number of hops, are presented. These results illustrate that ADCD allows mitigating the information redundancy and its delivery with an adequate latency while making the reception of interesting data for the drivers (related to their location) more adapted. Moreover, the ADCD protocol reduces the overhead by 90% compared with the classical broadcast and an adapted version of MobEyes. The ADCD overhead is kept stable whatever the vehicular density.
Wireless Communications and Mobile Computing 11/2011; 11(12):1689–1701. · 0.86 Impact Factor
[show abstract][hide abstract] ABSTRACT: Over the last decade cooperative communication in wireless sensor networks (WSN) received much attention. A lot of works have been done to propose a MAC layer that supports cooperative communication. However the impact of the association of a cooperative communication technique with a low power listening scheme was not studied in the literature. In this paper we propose CL-MAC, a Cooperative Low power mac protocol for WSNs. CL-MAC implements jointly Low Power Listening and cooperative communication. More precisely, we propose two variants of this protocol: a proactive version CL-MAC(P) and a reactive version CL-MAC(R). In order to evaluate the performances of the two proposed CL-MAC variants, we compare its to those of X-MAC. Simulation results proved that our protocol is able to enhance the use of the channel and to reach promising energy preservation especially in dense networks.
Communications (ICC), 2011 IEEE International Conference on; 07/2011
[show abstract][hide abstract] ABSTRACT: The relay-assisted Orthogonal Frequency-Division Multiple Access (OFDMA) cellular system is one of the most promising technology thanks to the enhancements of the system capacity and coverage it provides. However, some special features may lower its positive aspects. In multiple relay case, the asymmetric link problem in the two stages forming the relaying process may result in important resource wastage. Such resource wastage can even be more serious than in the case where only a single relay is used in the system. Only few works consider this resource wastage problem. In this paper, we first define a new term, channel holes, to denote the potential resource wastage in single and multiple relay systems. Then based on this new concept, we propose a novel resource management scheme for multiple relay systems, i.e. channel-hole based cooperative scheduling in multiple relay systems. In order to evaluate the performances of such resource management schemes, we build a system model and propose the corresponding analytical derivation, which helps analyzing the average queue length and the average packet delay. Simulations are used to validate and reinforce our theoretical analysis. Then using simulations, we compare our proposed scheduling algorithm to other algorithms from the literature. Hence, we show that our proposed algorithm performs better than others. In addition we also observe that our proposed scheduling algorithm performs a resource-aware relay selection that is more efficient than the one obtained using the ideal relay selection scheme.
Communications (ICC), 2011 IEEE International Conference on; 07/2011
[show abstract][hide abstract] ABSTRACT: Over the last decade cooperative communication in wireless sensor networks (WSN) received much attention. A lot of works have been done to propose a MAC layer that supports cooperative relaying. The majority of these works tried to adapt the IEEE 802.11 MAC protocol to sensor networks. The adapted protocols use a lot of overhead (such as the use of RTS/CTS as well as other messages used to allow cooperation) that consumes energy. In this paper we propose a CSMA/CA based MAC protocol that supports cooperative communication with a minimum overhead: COSMIC (A Cooperative MAC Protocol for WSN with Minimal Control Messages). Relay selection in this new protocol is performed using both the channel state information (CSI) and the remaining energy. Simulation results show that COSMIC is able to increase the network lifetime by 25%.
New Technologies, Mobility and Security (NTMS), 2011 4th IFIP International Conference on; 03/2011
[show abstract][hide abstract] ABSTRACT: This paper describes CoZi, a new packet scheduling mechanism for large scale ZigBee networks. CoZi aims at enhancing the reliability of the data delivery and the bandwidth utilization of the network. Based on simple network coding, instead of the classic packet forwarding, our algorithm takes advantage of the shared nature of the wireless medium as well as the cluster-tree topology of IEEE 802.15.4 networks to increase the global throughput and to reduce transmissions in end-to-end and dissemination-based communications.
Global Telecommunications Conference (GLOBECOM 2010), 2010 IEEE; 01/2011
[show abstract][hide abstract] ABSTRACT: This paper introduces a network coding scheme that significantly increases the performances of clustering algorithms in wireless multi-hop networks. Knowing the promising capabilities of network coding over broadcast mediums, we propose a simple and non-invasive packet scheduling mechanism based on proactive code selection and overheard messages to optimize intra and inter-cluster communications. Our solution uses bitwise XOR operations at the packet level to combine several messages in one transmission. Simulations show an important gain in the network reliability, and a major enhancement of the throughput without any substantial computation or network overhead.
Proceedings of the IFIP Wireless Days Conference 2011, Niagara Falls, ON, Canada, October 10-12, 2011; 01/2011
[show abstract][hide abstract] ABSTRACT: Smart phones, PDA, Sensors, Actuators, Phidgets and Smart Objects (i.e. objects with processing and networking capabilities) are more and more present in everyday's life. Merging all these technologies with the Internet is often described as 'Internet of Things' (IoT). In the IoT vision, Things around us provide a pervasive network of interacting and interconnected devices. However building IoT applications is a long and arduous work, reserved for specialists, requiring specific knowledge's in terms of network protocols and programming languages. The lack of widespread and easy-to-configure solutions is an obstacle for the development of this area. A universal framework, offering simplification and standardization, could facilitate the emergence of this promising field in terms of applications and business. IoT needs a solid foundation for rapid, simple development and deployment of new services. In this paper, we present D-LITe, a universal framework for building IoT applications over heterogeneous sets of small devices. D-LITe offers solutions for deploying application's logic, and executing it on Smart Objects despite their heterogeneity. An implementation of D-LITe on tiny devices, such as TelosB motes, allows to show that our framework is realistic even with the constraints of such devices.
[show abstract][hide abstract] ABSTRACT: The proliferation of low power networks like Wireless Sensor Networks (WSN) rose up new challenges. Power conservation and channel quality become the most important parameters. Obviously, hop count based routing protocols are no more adapted to such networks having power limitations and channel problems. Several alternatives were suggested to cope with these constraints. In MAC layer for example, cooperative protocols were designed to enhance the channel use: the neighbor nodes help the source to retransmit its packets. However, if the path proposed by the routing protocol contains poor channels, the cooperative communications will not save all the packets. Therefore, the design of new routing protocol becomes compulsory. In this paper we propose ECAR, a routing protocol that optimizes two objectives at the same time: energy and Channel State Information (CSI). Compared to AODV, ECAR provides considerable enhancements in delivery ratio, end-to-end delay and power consumption.
IEEE 22nd International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2011, Toronto, ON, Canada, September 11-14, 2011; 01/2011
[show abstract][hide abstract] ABSTRACT: TCP suffers dramatically when implemented within wireless multi-hop ad-hoc networks due to its specific characteristics (e.g. mobility and being battery dependant). Being battery operated, ad-hoc network nodes have to be energy conservative. Many researches investigated the performance of TCP in terms of throughput and/or energy consumption. Energy consumption studies, however, were only partial. This paper introduces complete, detailed measurements of TCP’s energy consumption resulting from both communication and computational energy costs. Our measurements are realized using a hybrid approach, combining simulations and realistic test-bed configuration. Our study is conducted taking into account different TCP variants facing various data loss situations within the network. The obtained results show the impact of TCP’s congestion control algorithm on TCP’s energy cost.
[show abstract][hide abstract] ABSTRACT: Extensive research addressing IEEE 802.11e enhanced distributed channel access (EDCA) performance analysis, by means of analytical models, exist in the literature. Unfortunately, the currently proposed models, even though numerous, do not reach this accuracy due to the great number of simplifications that have been done. Particularly, none of these models considers the 802.11e contention free burst (CFB) mode which allows a given station to transmit a burst of frames without contention during a given transmission opportunity limit (TXOPLimit) time interval. Despite its influence on the global performance, TXOPLimit is ignored in almost all existing models. To fill in this gap, we develop in this paper a new and complete analytical model that (i) reflects the correct functioning of EDCA, (ii) includes all the 802.11e EDCA differentiation parameters, (iii) takes into account all the features of the protocol, and (iv) can be applied to all network conditions, going from nonsaturation to saturation conditions. Additionally, this model is developed in order to be used in admission control procedure, so it was designed to have a low complexity and an acceptable response time. The proposed model is validated by means of both calculations and extensive simulations.
[show abstract][hide abstract] ABSTRACT: The increasing popularity of network-based multimedia applications poses many challenges for multimedia content providers to supply efficient and scalable multimedia services. Peer-to-Peer (P2P) networks have been shown to be a promising approach to provide large scale video services over Internet since they increase the scalability and robustness. In this paper, we propose and analyze an object management policy approach for video web cache in a P2P context, taking advantage of object's meta-data, e.g video popularity, and object's encoding techniques, e.g Scalable Video Coding (SVC). We exploit the peer-to-peer based approach to carry out the replication then eviction of videos in different web cache according to their popularity. Since videos are typically large and require high communication bandwidth for delivery, many peers may be unwilling to cache them in whole to serve others. Accordingly, we address this problem by proposing a new web caching approach for videos encoded in layers. Furthermore, in the proposed approach cooperation amongst the web caches may make it possible to replicate the video on several caches when this one is very popular. Afterward, we can gradually eliminate the replicas from the caches as the video popularity decrease. In addition, we structure our peer-to- peer network using interest-based communities. This network is made by ordinary nodes and super-nodes, and with peers clustered into communities. These communities are built around subjects (e.g., Science and Sports). The performance measurements we carried out allowed analyzing the traffic volume that flows from the community super-node to the first server into our content delivery network. The main goal is to measure how much our content-oriented management policy can help to decrease the demands put over the community output link. These measurements showed that the proposed approach (i) reduces the traffic volume, (ii) maximizes the overall bit rate of community demands, and-
(iii) optimizes the use of network resources.
IEEE Latin America Transactions 09/2010; · 0.22 Impact Factor
[show abstract][hide abstract] ABSTRACT: Most of current works related to relay selection algorithms in cooperative communications use the Channel State Information (CSI) to decide whether to use one or another neighbor as a relay. Therefore in wireless sensor networks where the energy is the major constraint such algorithms may lead to quick battery drain of the nodes having the best links. In this paper we propose to enhance the relay selection decision process by taking into account the energy metric in addition to CSI. The results show that we can redistribute the consumed energy when we use the energy as a relay selection metric.
[show abstract][hide abstract] ABSTRACT: Vehicular ad hoc networks (VANETs) have received considerable attention in recent times. Multihop data delivery between vehicles is an important aspect for the support of VANET-based applications. Although data dissemination and routing have extensively been addressed, many unique characteristics of VANETs, together with the diversity in promising applications, offer newer research challenges. This paper introduces the improved greedy traffic-aware routing protocol (GyTAR), which is an intersection-based geographical routing protocol that is capable of finding robust and optimal routes within urban environments. The main principle behind GyTAR is the dynamic and in-sequence selection of intersections through which data packets are forwarded to the destinations. The intersections are chosen considering parameters such as the remaining distance to the destination and the variation in vehicular traffic. Data forwarding between intersections in GyTAR adopts an improved greedy carry-and-forward mechanism. Evaluation of the proposed routing protocol shows significant performance improvement in comparison with other existing routing approaches. With the aid of extensive simulations, we also validate the optimality and sensitivity of significant GyTAR parameters.
IEEE Transactions on Vehicular Technology 12/2009; · 2.06 Impact Factor