Pubs:2006

<bibtex> @inproceedings{170, author={C. Thorpe; S. Murphy; L. Murphy}, title={Seamless Handover in Heterogeneous Radio Access Networks}, booktitle={IT&T}, year={2006}, abstract={This paper provides a detailed discussion of the problem of Seamless Handover in Heterogeneous Radio Access Networks. Brief descriptions of several wireless access technologies are included to provide some background information and to illustrate the importance of solving the seamless handover problem for network subscribers. Several approaches to providing a handover solution have been proposed, some of which will be described and compared, in order to indicate possible directions for continuing to search for a seamless handover solution. Various problems are present in the existing solutions, and are discussed in this paper. These problems are significant enough to warrant further investigation in the handover area, and leave scope for modifications and improvements.}, keywords={Seamless Handover, Heterogenous Networks, SCTP}, pdf={christina-itt06-cameraReady.pdf}, } </bibtex> <bibtex> @inproceedings{161, author={C. Thorpe; L. Murphy}, title={A Survey of Seamless Handover in Heterogeneous Radio Access Networks}, booktitle={ACM/IEEE International Symposium on Modeling, Analysis and Simulation of Wireless and Mobile Systems}, year={2006}, abstract={This paper provides a detailed discussion of the problem of Seamless Handover in Heterogeneous Radio Access Networks. Several approaches to providing a handover solution have been proposed, some of which will be described and compared, in order to indicate possible directions for continuing to search for a seamless handover solution. Various problems are present in the existing solutions, and are discussed in this paper. }, keywords={Seamless Handover, Heterogenous Networks, SCTP}, pdf={Christina-MSWIM-Oct-2006.pdf}, } </bibtex> <bibtex> @inproceedings{213, author={J. Fitzpatrick, S. Murphy and J. Murphy}, title={An Approach to Transport Layer Handover of VoIP over WLAN}, booktitle={CCNC}, year={2006}, abstract={In this paper a transport layer handover mechanism for Voice over Internet Protocol (VoIP) using the Stream Control Transmission Protocol (SCTP) is proposed. This handover mechanism utilizes the multi-homing feature of SCTP to allow connection to multiple wireless networks. Each available wireless network is probed with simulated VoIP data to obtain network performance metrics. Handover decisions are made based on the Mean Opinion Score (MOS) calculated from the ITU-T E-Model for voice quality assessment using the obtained measurements. Implementation and simulations were carried out using the NS2 network simulator. The results show the MOS obtained using the proposed handover mechanism on IEEE 802.11b WLAN access points (APs) under varying load conditions. High correlation is shown between the MOS from the proposed handover scheme and the MOS experienced by a VoIP node present in the network. A simulation showing an SCTP endpoint handover between AP’s is presented.}, keywords={SCTP, E-Model, VoIP, Handover, Heterogeneous Networks}, } </bibtex> <bibtex> @inproceedings{214, author={J. Fitzpatrick, and S. Murphy, and J. Murphy,}, title={SCTP based Handover Mechanism for VoIP over IEEE 802.11b Wireless LAN with Heterogeneous Transmission Rates}, booktitle={Communications, 2006. ICC '06. IEEE International Conference on}, year={2006}, abstract={In this paper a transport layer handover mechanism for Voice over Internet Protocol (VoIP) in 802.11b using the Stream Control Transmission Protocol (SCTP) is proposed. The multi-homing feature of SCTP is used to allow connections to several 802.11b Access Points (AP's). Probing packets that model VoIP encoded data at various transmission rates are used to obtain quality metrics from each of the available networks. Handover decisions are made based on the Mean Opinion Score (MOS) calculated from the ITU-T E-Model for voice quality assessment using the obtained measurements. The handover mechanism is shown to operate in 802.11b networks with heterogeneous transmission rates using multiple VoIP codecs. The results show a high correlation between the MOS predicted by the proposed mechanism and the MOS experienced by a VoIP call present in the network. Results verify the accurate operation of the scheme using multiple VoIP codecs at various transmission rates. A simulation showing an SCTP endpoint handover between heterogeneous transmission rate AP's is presented.}, keywords={SCTP, VoIP}, } </bibtex> <bibtex> @inproceedings{215, author={J. Fitzpatrick, S. Murphy, J. Murphy}, title={RTS/CTS Based Endpoint Admission Control for VoIP Over 802.11e}, booktitle={MMNS}, year={2006}, abstract={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.}, keywords={Call Admission Control, VoIP, 802.11e, RTS/CTS}, } </bibtex> <bibtex> @inproceedings{311, author={Carrig,B.;Denieffe,D.;Murphy,J.}, title={A Relative Delay Minimization Scheme for Multiplayer Gaming in Diffrentiated Services Network}, booktitle={ACM SIGCOMM Workshop on Network & System Support for Games}, year={2006}, abstract={Multiplayer gaming over the Internet continues to grow in popularity, despite a lack of Quality of Service (QoS) mechanisms. Future QoS-aware networks such as those based on the Differentiated Services (DiffServ) framework will provide an opportunity for gamers to enhance their game-playing experience. An important QoS metric for networked games is a user’s delay relative to the delay of other users. In this paper, we propose a Relative Delay Minimization (RDM) algorithm for use in DiffServ environments. Simulation results are described and presented showing that the algorithm can reduce the Relative Delay Variation (RDV) between users in a DiffServ environment.}, keywords={Network Games, Relative Delay, DiffServ, QoS}, pdf={a relative delay.pdf}, } </bibtex>