Catálogo de publicaciones - libros

This paper proposes an integrated network management framework for inter-domain outbound traffic engineering. The framework consists of three functional blocks (monitoring, optimization and implementation) to make the outbound traffic engineering adaptive to network condition changes such as inter-domain traffic demand variation, inter-domain routing changes and link failures. The objective is to keep the inter-domain link utilization balanced under any of these changes while reducing service disruptions and reconfiguration overheads. Simulation results demonstrate that the proposed framework can achieve better load balancing with less service disruptions and re-configuration overheads in comparison to alternative approaches.

In this paper an endpoint-based admission control mechanism for VoIP over WLAN is proposed. The mechanism operates by first measuring the utilisation of the channel and comparing this to a pre-determined threshold, if the channel utilisation exceeds this threshold, the call is rejected. One important aspect of the mechanism is that it can operate in the presence of hidden terminals. This is done by using the Request-to-Send/Clear-to-Send WLAN signalling to determine channel utilisation. The scheme is designed to be flexible; it can operate with heterogeneous data rates, with varying traffic types and in the presence of legacy 802.11 nodes. The scheme was developed and evaluated using the Qualnet network simulator. An empirical approach was used to determine appropriate admission thresholds. Then, simulations were performed to demonstrate the successful operation of the scheme.

Stability is an important issue in multicast, especially in mobile environment where joining and leaving behaviors occur much more frequently. In this paper, we propose a scheme to improve the multicast stability by the use of motion prediction. The mobile node (MN) predicts the staying time before entering the new network, if the time is long enough, it will ask the new network to join the multicast tree as usual. Otherwise, the new network should create a tunnel to the multicast agent of MN to receive multicast packets. Considering that networks usually have different power range, the staying time is not predicted directly, and the Average Staying Time is used instead. The prediction algorithm is effective but practical which requires little calculation time and memory size. The simulation results show that the proposed scheme can improve the stability of multicast tree remarkably while bring much smaller cost.

The paper addresses the end-to-end QoS problem of MPEG4-FGS video streaming traffic delivery over a heterogeneous IP/UMTS network. It proposes and validates an architecture that explores the joint use of packet prioritization and scalable video coding together with the appropriate mapping of UMTS traffic classes to the DiffServ traffic classes. A set of simulation scenarios, involving eight different video sequences, demonstrates the quality gains of both scalable video coding and prioritized packetization.