Pau Arce

A QoS-aware routing protocol with adaptive feedback scheme for video streaming for mobile networks

One of the major challenges for the transmission of time-sensitive data like video over mobile ad-hoc networks (MANETs) is the deployment of an end-to-end QoS support mechanism. Therefore, several approaches and enhancements have been proposed concerning the routing protocols. In this paper we propose a new QoS routing protocol based on AODV (named AQA-AODV), which creates routes according to application QoS requirements. We have introduced link and path available bandwidth estimation mechanisms and an adaptive scheme that can provide feedback to the source node about the current network state, to allow the application to appropriately adjust the transmission rate. In the same way, we propose a route recovery approach into the AQA-AODV protocol, which provides a mechanism to detect the link failures in a route and re-establish the connections taking into account the conditions of QoS that have been established during the previous route discovery phase. The simulation results reveal performance improvements in terms of packet delay, number of link failures and connection setup latency while we make more efficient use of the available bandwidth than other protocols like AODV and QAODV. In terms of video transmission, the obtained results prove that the combined use of AQA-AODV and the scalable video coding provides an efficient platform for supporting rate-adaptive video streaming.

SVCEval-RA: an evaluation framework for adaptive scalable video streaming

Multimedia content adaption strategies are becoming increasingly important for effective video streaming over the actual heterogeneous networks. Thus, evaluation frameworks for adaptive video play an important role in the designing and deploying process of adaptive multimedia streaming systems. This paper describes a novel simulation framework for rate-adaptive video transmission using the Scalable Video Coding standard (H.264/SVC). Our approach uses feedback information about the available bandwidth to allow the video source to select the most suitable combination of SVC layers for the transmission of a video sequence. The proposed solution has been integrated into the network simulator NS-2 in order to support realistic network simulations. To demonstrate the usefulness of the proposed solution we perform a simulation study where a video sequence was transmitted over a three network scenarios. The experimental results show that the Adaptive SVC scheme implemented in our framework provides an efficient alternative that helps to avoid an increase in the network congestion in resource-constrained networks. Improvements in video quality, in terms of PSNR (Peak Signal to Noise Ratio) and SSIM (Structural Similarity Index) are also obtained.

Performance Evaluation of Scalable Video Streaming in Mobile Ad hoc Networks

The development of video streaming services on wireless ad hoc networks is a challenge task as a consequence of different limitations such as bandwidth-constrained, variable capacity links and energy-constrained operation. Moreover, the dynamic topology of nodes causes frequent link failures and high error rates. We propose in this paper a performance evaluation of the scalable video streaming over mobile ad hoc networks. In particular, we focus on the rate-adaptive strategy for streaming scalable video (H.264/SVC). In order to provide QoS mechanisms in the routing process, a new routing protocol is introduced. This protocol estimates the available bandwidth value, which is sent to video source in order to adapt the bit rate during the video transmission. We also propose a simulation framework that supports evaluation studies for scalable video streaming. In the simulation experiments, SVC streams with combined scalability (quality and temporal scalability) were used. As quality scalability method, we used Medium Grain Scalability (MGS). The results reveal that the rate-adaptive method helps avoid or reduce the congestion in MANETs obtaining a better quality in the received videos.

Route Recovery Algorithm for QoS-Aware Routing in MANETs

The communications inside MANETs usually show frequent disruptions due to changes in topology and the condition of having a shared physical channel. It is necessary to implement a mechanism to maintain connectivity and ensure Quality of Service (QoS). In this paper we introduce a route recovery mechanism for a QoS routing protocol called AQA-AODV (Adaptive QoS-Aware AODV) which is an extension of the AODV protocol. Our proposal provides a mechanism to detect the link failures in a route and reestablish the connections taking into account the conditions of QoS that have been established during the route discovery phase. The simulation results reveal performance improvements in terms of packet delay, number of link failures and connection setup latency while the end-to-end throughput is not affected compared with the throughput achieved by other protocols like AODV.

Simulation and experimental testbed for adaptive video streaming in ad hoc networks

This paper presents a performance evaluation of the scalable video streaming over mobile ad hoc networks. In particular, we focus on the rate-adaptive method for streaming scalable video (H.264/SVC). For effective adaptation a new cross-layer routing protocol is introduced. This protocol provides an efficient algorithm for available bandwidth estimation. With this information, the video source adjusts its bit rate during the video transmission according to the network state. We also propose a free simulation framework that supports evaluation studies for scalable video streaming. The simulation experiments performed in this study involve the transmission of SVC streams with Medium Grain Scalability (MGS) as well as temporal scalability over different network scenarios. The results reveal that the rate-adaptive strategy helps avoid or reduce the congestion in MANETs obtaining a better quality in the received videos. Additionally, an actual ad hoc network was implemented using embedded devices (Raspberry Pi) in order to assess the performance of the proposed adaptive transmission mechanism in a real environment. Additional experiments were carried out prior to the implementation with the aim of characterizing the wireless medium and packet loss profile. Finally, the proposed approach shows an important reduction in energy consumption, as the study revealed.

Hybrid FLUTE/DASH video delivery over mobile wireless networks

This paper describes how File Delivery over Unidirectional Transport FLUTE and Dynamic Adaptive Streaming over Hypertext Transfer Protocol DASH can be used to provide mobile video streaming services over broadcast wireless networks. FLUTE is a multicast protocol for multimedia file download. In this proposal, the protocol is adapted to provide video streaming services in crowded environments. Thus, video is delivered over a single connection to all viewers, reducing the traffic in the network. FLUTE incorporates an application-layer forward error correction AL-FEC mechanism in order to improve the reliability of the broadcast communication channel. For streaming applications, AL-FEC improves the relationship between the peak signal-to-noise ratio PSNR of the received video and the bandwidth allocated to the broadcast connection. The AL-FEC hereby presented applies simple unequal error protection schemes to favour the download of key frames. Furthermore, the proposal is based on the same video segmentation mechanism as DASH, and therefore, clients can connect to a DASH repository to repair errors in the segments. This paper shows that FLUTE and DASH can be seamlessly integrated into a hybrid broadcast/unicast streaming technology, providing flexibility to trade off PSNR and bandwidth depending on the conditions of the mobile network. Copyright

Effect of the Multiple Description Coding over a Hybrid Fixed-AdHoc Video Distribution Network

Offering a real time video transmission service, using mobile ad hoc networks (MANETs) and granting a specific Quality of Service (QoS) is a hard challenge. In fact, the network topology is extremely unstable and its variability causes the loss of transmitted information. However, powerful mechanisms against channel failures can be incorporated to avoid the system breakdown. In this paper, we evaluate the effect of Multiple Description Coding (MDC) technique for improving video quality in a multimedia content distribution system. The architecture proposed is a hybrid fixed and wireless ad hoc network where nodes can move freely. Due to multipoint to point nature of this system, multidescription can be combined with multipath transmission to increase its efficiency and, at last, the Quality of Experience (QoE) of the final receiver. The simulation lets us compare the quality of the video streaming paying attention to quality parameters (PSNR, packet delivery ratio, decodable frame rate and interruptions). Results show that MDC improves video quality in high mobility scenarios.

Simulation and Testbed Evaluation for Optimizing Energy Consumption in Ad Hoc Networks based on OLSR Protocol

This paper presents a proposal to optimize energy consumption in ad hoc networks based on the OLSR protocol. This approach focuses on the set up of routes with less congestion level and higher energy capacity. Therefore, in addition to the remaining energy of nodes, a new metric is introduced, the strategic value, which reports the importance of a specific node in the network based on the numbers of neighbors it has. In order to obtain valuable results, the evaluation was performed in a simulation environment (NS3) and on a real testbed. In that sense, an actual ad hoc network was implemented using embedded devices (Raspberry Pi). Results show a decrease in energy consumption, especially in zones with the highest device density, as well as an increase of the time of operation for nodes with higher amount of neighbors. Additionally, the performed evaluation shows a positive effect in the quality of traffic flows, avoiding route breakages and packet losses.

Energy optimization for video monitoring system in agricultural areas using single board computer nodes and wireless ad hoc networks

This paper presents the design and implementation of a set of prototype nodes that have the ability to establish communication links in ad hoc mode. The prototypes were implemented using low cost, single board computers with embedded Linux (Raspberry Pi devices). The implemented stations aim to set a wireless sensor network for the capture of variables applied to agricultural environments. In particular, a camera module has been included on a node for remote video monitoring of farming zones, and also a GPS module for the capture of geolocation information. Nodes can be accessed remotely by means of the developed web interface. The routing process between nodes is carried out using the S-OLSR mechanism (OLSR modification) in order to set up routes taking into account the energy limitations as well as the location of each device in the topology. Results describe the contribution of this work to the design of monitoring applications on agricultural zones by means of the deployment of autonomous ad hoc nodes and energy routing optimization.

Buffering Technique for Optimizing Energy Consumption in the Transmission of Multimedia Traffic in Ad-Hoc Networks

Energy constraints on wireless nodes represent a current field of research. Such restrictions are particularly significant because of the great amount of features and applications currently available on devices, which contribute to dramatically increase energy consumption. However, when transmitting delay-sensitive data, such as multimedia streaming, a balance between energy optimization and quality of service is required. In this sense, there are many works that address this issue from different layers of network architecture separately; however, a more efficient solution could be achieved by combining the management capabilities of the different layers and the joint use of such information, which is called a cross-layer mechanism. Moreover, despite the fact that the IEEE 802.11 standard defines an energy management mechanism at MAC level, it is envisaged only for structured networks, leaving just general guidelines for other kind of networks, such as Ad-Hoc networks. Therefore, as a first step towards the design of a cross-layer scheme, this paper analyzes the flaws of IEEE 802.11 standard as regards the infrastructureless mode and proposes an optimization mechanism for energy management in Ad-Hoc networks. The proposed approach is based on a buffering mechanism, which is able to increase power-saving periods of time in Ad-Hoc nodes. Simulations using NS3 indicate that it is possible to obtain higher levels of residual energy at the end of a transmission using the proposed scheme.