@article{hui_devetsikiotis_2008, title={The use of metamodeling for VoIP over WiFi capacity evaluation}, volume={7}, ISSN={["1558-2248"]}, DOI={10.1109/TWC.2008.05754}, abstractNote={The increasing popularity of wireless fidelity (Wi-Fi) networks at home, in public areas and in the enterprise motivates extensive modeling and analysis of their performance measures, such as network capacity and quality of service (QoS) capabilities. Some of the easier performance problems can be solved by analytical modeling methods, but most of the complicated ones, involving several design parameters from multiple layers, can only be answered through simulation studies that are typically implicit and less suitable for design and optimization. Hence, we believe it is crucial to obtain explicit mathematic models, that are effective in representing system behavior and a basis for performance optimization. Here, we first advocate the application of formal empirical modeling techniques to performance studies of Wi-Fi networks, in order to find usable, if approximate, closed-form mathematical models. Subsequently, by applying these metamodeling techniques, we perform a case study with very useful results: our VoWiFi (voice over Wi-Fi) admission capacity metamodel gives a much tighter bound than those existing in the literature and leads to a more effective admission control scheme. Our work, therefore, points out a new direction for future performance studies of Wi-Fi networks.}, number={1}, journal={IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS}, author={Hui, Jie and Devetsikiotis, Michael}, year={2008}, month={Jan}, pages={1–5} }
 @inproceedings{hui_devetsikiotis_2006, title={Metamodeling of Wi-Fi Performance}, DOI={10.1109/icc.2006.254849}, abstractNote={The increasing popularity of Wireless Fidelity (Wi-Fi) networks at home, in public areas and in the enterprise motivates extensive modeling and analysis of their performance measures, such as network capacity, resource requirements and quality of service (QoS) capabilities. Some of the easier performance problems can be solved by analytical modeling methods, but most of the complicated ones, involving too many factors from multiple layers, can only be answered through validated simulation models. However, an explicit mathematic model is always the most effective way to represent the system behavior and the most convenient basis for performance optimization. Here, we first advocate the application of metamodeling techniques to performance studies of Wi-Fi networks, in order to find usable, if approximate, closed-form mathematical models. Subsequently, we formulate a general metamodeling framework for Wi-Fi networks. Our results in two relevant case studies, after applying this framework, support the validity of our metamodeling methodology: our capacity metamodel for 802.11 Distributed Coordination Function (DCF) is validated by a well-known analytical model and displays an interesting log-linear relationship between capacity and number of users; our voice over Wi-Fi admission capacity metamodel gives a much tighter bound than bounds existing in the literature and composes a more practical admission control scheme. Our work, therefore, points out a new direction for future performance studies of Wi-Fi networks.}, booktitle={2006 ieee international conference on communications, vols 1-12}, author={Hui, J. and Devetsikiotis, M.}, year={2006}, pages={527–534} }
 @article{hui_devetsikiotis_2005, title={A unified model for the performance analysis of IEEE 802.11e EDCA}, volume={53}, ISSN={["1558-0857"]}, DOI={10.1109/tcomm.2005.855013}, abstractNote={Rapid deployment of IEEE 802.11 wireless local area networks (WLANs) and their increasing quality of service (QoS) requirements motivate extensive performance evaluations of the upcoming 802.11e QoS-aware enhanced distributed coordination function (EDCA). Most of the analytical studies up-to-date have been based on one of the three major performance models in legacy distributed coordination function analysis, requiring a large degree of complexity in solving multidimensional Markov chains. Here, we expose the common guiding principle behind these three seemingly different models. Subsequently, by abstracting, unifying, and extending this common principle, we propose a new unified performance model and analysis method to study the saturation throughput and delay performance of EDCA, under the assumption of a finite number of stations and ideal channel conditions in a single-hop WLAN. This unified model combines the strengths of all three models, and thus, is easy to understand and apply; on the other hand, it helps increase the understanding of the existing performance analysis. Despite its appealing simplicity, our unified model and analysis are validated very well by simulation results. Ultimately, by means of the proposed model, we are able to precisely evaluate the differentiation effects of EDCA parameters on WLAN performance in very broad settings, a feature which is essential for network design.}, number={9}, journal={IEEE TRANSACTIONS ON COMMUNICATIONS}, author={Hui, J and Devetsikiotis, M}, year={2005}, month={Sep}, pages={1498–1510} }