The increasing spread of mobile nodes along with the technical advances in multi-hop MANETs (Mobile Ad hoc NETworks) make this kind of networks an important type of access network of next generation. The demand of multimedia services from these networks is expected to significantly grow in the next years. Multimedia services, though, require the provision of Quality of Service (QoS). Nevertheless, the highly dynamic nature of MANETs, the energy constraints, the lack on centralized infrastructure and the variable link capacity, makes the QoS provision over MANETs a matter that challenges attention. These features make self-configuration and system adaptation questions of major importance when developing a QoS-aware framework. To tackle this issue, we have designed a-MMDSR (adaptive-Multipath Multimedia Dynamic Source Routing), a multipath routing protocol able to self-configure dynamically depending on the state of the network. The approach includes cross-layer techniques especially designed to improve the end-to-end performance of video-streaming services over IEEE 802.11e Ad Hoc networks. Besides, a straightforward analytical model to estimate the path error probability is presented. This model is used by the routing scheme to estimate the lifetime of the paths. In this way, proper proactive decisions can be made before the paths get broken. The model simplicity is appropriate for low capacity wireless devices. Simulation results validate the proposal and show the improvement on standard DSR (Dynamic Source Routing) and on a previous static version.
End-to-end Quality of Service (QoS) provision to video-streaming applications over Mobile Ad hoc Networks (MANETs) poses a specially challenging problem. In this paper we propose a Cross-Layer (XL) network architecture design to optimize the overall performance of video-streaming services over MANETs, called ViStA-XL. The idea relies on applying several optimization strategies to different network layers in a holistic way. In our proposal, a real-time XL Optimizer (XLO) collects information about the node and network states from different layers of the network's protocol stack. Then, in order to minimize the error between received and transmitted video, the XLO module takes the necessary decisions to act dynamically over different layers' parameters. In addition, our proposal exploits path diversity as a mean to reinforce QoS provision to layered-coded video-streaming applications, by protecting the most important video information packets. To show the advantages of our approach, we have developed an algorithm based on ViStA-XL. Simulation results show that our proposed network design can improve the performance of videostreaming transmissions over MANETs in spite of frequent changes in network topology and node's conditions.
Mobile Ad hoc NETworks (MANETs) are nowadays being used much more than some years ago. One of the major reasons is the increasing number of devices that have risen lately capable of forming part of such networks. This situation makes feasible the development of new services. Especially, videostreaming is one of the most successful services demanded by the customers. In this paper we propose a QoS-aware multipath DSR-based (Dynamic Source Routing) routing protocol which helps to improve the reliability of the connections while balancing the load and decreasing the end-to-end delay. Several multipath routing designs have been evaluated seeking to get better global performance of the network. Besides, we propose a QoS-aware architecture that includes a cross-layer scheme in which a network layer scheduler manages different priority traffics and operates according to the IEEE 802.11e MAC (Medium Access Control) layer. Extensive simulations have been carried out to show the benefits of our scheme in providing different levels of QoS, including user-level QoS parameters.
The number of portable electronic devices capable of maintaining wireless communications increases day by day. Such mobile nodes may easily self-configure to form a Mobile Ad Hoc Network (MANET) without the help of any established infrastructure. As the number of mobile devices grows, the demand of multimedia services such as video-streaming from these networks is foreseen to increase as well. This paper presents a proposal which seeks to improve the experience of the end users in such environment. The proposal is called dCW-MMDSR (dynamic Contention Window-Multipath Multimedia Dynamic Source Routing), a cross-layer multipath routing protocol which includes techniques to achieve a dynamic assignment of the Contention Window of the IEEE 802.11e MAC level. In addition, it includes multipath routing suitable for layered coded video to improve the performance of the service. The operation is simple and suitable for low capacity wireless devices. Simulations show the benefits under different scenarios.
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