Alberto J. Gonzalez

A fuzzy logic approach to beaconing for vehicular ad hoc networks

Vehicular Ad Hoc Network (VANET) is an emerging field of technology that allows vehicles to communicate together in the absence of fixed infrastructure. The basic premise of VANET is that in order for a vehicle detect other vehicles in the vicinity. This cognizance, awareness of other vehicles, can be achieved through beaconing. In the near future, many VANET applications will rely on beaconing to enhance information sharing. Further, the uneven distribution of vehicles, ranging from dense rush hour traffic to sparse late night volumes creates a pressing need for an adaptive beaconing rate control mechanism to enable a compromise between network load and precise awareness between vehicles. To this end, we propose an intelligent Adaptive Beaconing Rate (ABR) approach based on fuzzy logic to control the frequency of beaconing by taking traffic characteristics into consideration. The proposed ABR considers the percentage of vehicles traveling in the same direction, and status of vehicles as inputs of the fuzzy decision making system, in order to tune the beaconing rate according to the vehicular traffic characteristics. To achieve a fair comparison with fixed beaconing schemes, we have implemented ABR approach in JIST/SWANs. Our simulation shows that the proposed ABR approach is able to improve channel load due to beaconing, improve cooperative awareness between vehicles and reduce average packet delay in lossy/lossless urban vehicular scenarios.

Context-aware multimedia service composition using quality assessment

With the proliferation of multimedia capable devices, media services have to deal with heterogeneous environments where very different types of terminals wish to receive content anywhere and anytime. This situation motivates the appearance of multimedia services that adapt contents to the specific context of users. However, current Internet architecture is based on a rigid layered model, which makes difficult to introduce new functionalities efficiently. To solve this, Service Oriented Architectures (SOA) appear with the goal of proposing new architectures based on services that can be invoked when and where necessary. This work introduces how SOA paradigm can be applied to context-aware multimedia communications. In addition, a scoring function for selecting different service implementations is presented and particularized for a case of selecting transcoding functions taking into account different quality assessment metrics.

Fuzzy redundancy adaptation and joint source-network coding for VANET video streaming

Video communication VANETs has many applications, such as emergency video transmission or inter-vehicle entertainment. However, delivering video to high mobile vehicles faces challenges such as packet loss due to intermittent connectivity and channel variations. Thus, designing a reliable approach for video streaming over such harsh scenarios is needed. Hence, we propose a reliable approach based on random practical network coding and source coding. This approach integrates the benefits of network coding with Multiple Description Coding to achieve robust streaming over VANET. Furthermore, we propose a redundancy controller based on fuzzy inference system to adjust the amount of redundant packets based on vehicular traffic density and SNR of the channel. Simulation shows the proposed approach achieves better protection against packet loss, application layer throughput and video quality.

Costing framework for service-oriented future internet architectures: empowering requester's choice

Internet is evolving fast thanks to the rising of new services and applications. This situation allowed realizing about current Internet deficiencies. Nowadays, researchers are proposing novel Internet architectures avoiding the rigidity of the layered structure posed by the TCP/IP stack. Service Oriented Architectures (SOA) principles are appropriate for proposing a flexible and scalable Internet architecture, which relies on the combination of services according to the requester needs. In this context it is necessary to introduce a framework for cost and price that enables requesters and providers to interact and create new business models for the Future Internet (FI). This work proposes a novel costing framework for providing services adapted to requester requirements.

Structured Peer-to-Peer Real Time Video Transmission over Vehicular Ad Hoc Networks

Video communication over Vehicular Ad Hoc Networks (VANET) has several applications such as road safety, commercial advertisements and on-road entertainment. In this paper we present a structured peer-to-peer (P2P) network designed for the distribution of live-content, with low bandwidth consumption, within a VANET. This P2P network is modelled using a media distribution graph. The implementation of a structured network allows a peer to schedule consecutive data chunks produced by the media source by means of a scheduling algorithm. In our analysis we obtain a bound for the maximum delay between the media source and any of the peers of the network and the buffer size needed to allow consecutive scheduling. We study a type of media distribution graph and we calculate its order and diameter, which means that under stable conditions we can ensure certain quality-of-service parameters. The results of simulation over NS2 show the fitness of the mathematical analysis.

Evaluating MDC with incentives in P2PTV systems

The popularity of P2P video streaming is raising the interest of broadcasters, operators and service providers. Concretely, mesh-pull based P2P systems are the most extended ones. Despite these systems address scalability efficiently, they still present limitations that difficult them to offer the same user experience in comparison with traditional TV. These ones are mainly the free-riding effect, long start-up delays and the impact of churn and bandwidth heterogeneity. In this paper we study the performance of Multiple Description Coding (MDC) combined with the use of incentives for redistribution in order to mitigate some of them by means of simulations. Simulation results show that the use of MDC and incentive-based scheduling strategies improve the overall performance of the system. Moreover, an extended version of the P2PTVSim simulator has been developed to support MDC and incentives.