Fernando Cerdán

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TCP, the dominant transport protocol for Internet applications, suffers severe performance degradation due to packet losses when a wireless link is present in the end-to-end path. For this reason, the 3G specification entity, 3GPP, has defined a reliable link layer protocol, RLC, to support packet switched services over UMTS. RLC provides error recovery in(More)
In this paper we present a new mechanism to provide an assured service in terms of target rate and fair excess bandwidth, like the Internet Assured Service. Research in Internet Assured Service faced up both questions in separate ways proposing different traffic conditioners to work with the RIO buffer management, and proposing different modifications to(More)
Traffic conditioners play a key role in implementing the Assured Service in the framework of the DiffServ approach. Many research papers have focused on finding the best traffic conditioner able to assure contracted target rates and to fairly distribute the excess bandwidth among competing sources. Nevertheless, none of the proposals presented so far(More)
A key objective of ATM-based networks is to provide at the same time guaranteed QoS to real time and non-real time services. This calls for thoroughly engineered traffic control methods for those service categories as well as for the overall integration strategy. The main objective of this paper is to investigate CAC in an ATM testbed with real switches and(More)
Recent demands for new applications are giving rise to an increasing need of Quality of Service (QoS). Nowadays, most IP-based networks tend to use the DiffServ architecture to provide end-to-end QoS. Traffic conditioners are a key element in the deployment of DiffServ. In this paper, we introduce a new approach for traffic conditioning based on feedback(More)
— Transport channel synchronization in 3G access networks is currently based on a simple algorithm that tries to track the delay of the link by adding or subtracting a constant step. We propose an algorithm that improves the responsiveness of the system under abrupt delay changes, reducing frame losses. Our proposal is faster than the proportional tracking(More)
TCP performance over 3G links can be enhanced by means of Active Queue Management (AQM) techniques at the downlink buffer of the mobile network link layer (RLC). In this paper we describe Slope Based Discard (SBD), a novel deterministic buffer management technique whose discarding policy is based on the observation of the filling rate of the buffer. By(More)
This paper describes a simulator of dedicated channels in 3G radio access networks, with TCP traffic. The design principles of this simulator and the experiments performed in it are explained in depth. We provide specific implementation details of RLC functions in OMNeT++. The main objective of the simulator is RLC parameter configuration. Although many(More)