Análisis de tráfico, modelación y simulación del tráfico de video en redes Wi-Fi 802.11e

Las WLAN (Wireless LAN) basadas en IEEE 802.11 se han vuelto las redes más populares en el acceso a los servicios de red y de banda ancha móvil/wireless a Internet. Y se espera que en los próximos años los servicios y aplicaciones de streaming o interactivos de video, alcancen hasta un 70% del tráfico total sobre dichas redes. En orden a satisfacer los requerimientos de QoS (Quality of Service - Calidad de Servicio) se introdujo la tecnología Wi-Fi EDCA (Enhanced Distributed Channel Access) 802.11e. Diferentes líneas de investigación estudian el comportamiento de la norma 802.11e, para mejorar sus mecanismos de diferenciación de tráfico a nivel MAC, en orden a gestionar y priorizar aún más eficientemente los diferentes perfiles de tráfico. En este trabajo de investigación se pretende efectuar capturas y mediciones de tráfico de video en redes Wi- Fi 802.11e, obtener su modelación y simulación usando Redes de Petri con el simulador Möbius (Universidad de Illinois). El objetivo es determinar por simulación, en escenarios previstos al efecto, el impacto cuantitativo y cualitativo que tendrá en la QoS de las redes Wi-Fi 802.11e, la mezcla de tráficos diversos con alta presencia de tráfico de streaming de video o tráfico de videoconferencias.Eje: Arquitectura, Redes y Sistemas OperativosRed de Universidades con Carreras en Informática (RedUNCI

Análisis de tráfico, modelación y simulación del tráfico de video en redes Wi-Fi 802.11e

Las WLAN (Wireless LAN) basadas en IEEE 802.11 se han vuelto las redes más populares en el acceso a los servicios de red y de banda ancha móvil/wireless a Internet. Y se espera que en los próximos años los servicios y aplicaciones de streaming o interactivos de video, alcancen hasta un 70% del tráfico total sobre dichas redes. En orden a satisfacer los requerimientos de QoS (Quality of Service - Calidad de Servicio) se introdujo la tecnología Wi-Fi EDCA (Enhanced Distributed Channel Access) 802.11e. Diferentes líneas de investigación estudian el comportamiento de la norma 802.11e, para mejorar sus mecanismos de diferenciación de tráfico a nivel MAC, en orden a gestionar y priorizar aún más eficientemente los diferentes perfiles de tráfico. En este trabajo de investigación se pretende efectuar capturas y mediciones de tráfico de video en redes Wi- Fi 802.11e, obtener su modelación y simulación usando Redes de Petri con el simulador Möbius (Universidad de Illinois). El objetivo es determinar por simulación, en escenarios previstos al efecto, el impacto cuantitativo y cualitativo que tendrá en la QoS de las redes Wi-Fi 802.11e, la mezcla de tráficos diversos con alta presencia de tráfico de streaming de video o tráfico de videoconferencias.Eje: Arquitectura, Redes y Sistemas OperativosRed de Universidades con Carreras en Informática (RedUNCI

Video traffic modeling and delivery

Video is becoming a major component of the network traffic, and thus there has been a great interest to model video traffic. It is known that video traffic possesses short range dependence (SRD) and long range dependence (LRD) properties, which can drastically affect network performance. By decomposing a video sequence into three parts, according to its motion activity, Markov-modulated self-similar process model is first proposed to capture autocorrelation function (ACF) characteristics of MPEG video traffic. Furthermore, generalized Beta distribution is proposed to model the probability density functions (PDFs) of MPEG video traffic. It is observed that the ACF of MPEG video traffic fluctuates around three envelopes, reflecting the fact that different coding methods reduce the data dependency by different amount. This observation has led to a more accurate model, structurally modulated self-similar process model, which captures the ACF of the traffic, both SRD and LRD, by exploiting the MPEG structure. This model is subsequently simplified by simply modulating three self-similar processes, resulting in a much simpler model having the same accuracy as the structurally modulated self-similar process model. To justify the validity of the proposed models for video transmission, the cell loss ratios (CLRs) of a server with a limited buffer size driven by the empirical trace are compared to those driven by the proposed models. The differences are within one order, which are hardly achievable by other models, even for the case of JPEG video traffic. In the second part of this dissertation, two dynamic bandwidth allocation algorithms are proposed for pre-recorded and real-time video delivery, respectively. One is based on scene change identification, and the other is based on frame differences. The proposed algorithms can increase the bandwidth utilization by a factor of two to five, as compared to the constant bit rate (CBR) service using peak rate assignment

Resource Allocation for Cellular/WLAN Integrated Networks

The next-generation wireless communications have been envisioned to be supported by heterogeneous networks using various wireless access technologies. The popular cellular networks and wireless local area networks (WLANs) present perfectly complementary characteristics in terms of service capacity, mobility support, and quality-of-service (QoS) provisioning. The cellular/WLAN interworking is thus an effective way to promote the evolution of wireless networks. As an essential aspect of the interworking, resource allocation is vital for efficient utilization of the overall resources. Specially, multi-service provisioning can be enhanced with cellular/WLAN interworking by taking advantage of the complementary network strength and an overlay structure. Call assignment/reassignment strategies and admission control policies are effective resource allocation mechanisms for the cellular/WLAN integrated network. Initially, the incoming calls are distributed to the overlay cell or WLAN according to call assignment strategies, which are enhanced with admission control policies in the target network. Further, call reassignment can be enabled to dynamically transfer the traffic load between the overlay cell and WLAN via vertical handoff. By these means, the multi-service traffic load can be properly shared between the interworked systems. In this thesis, we investigate the load sharing problem for this heterogeneous wireless overlay network. Three load sharing schemes with different call assignment/reassignment strategies and admission control policies are proposed and analyzed. Effective analytical models are developed to evaluate the QoS performance and determine the call admission and assignment parameters. First, an admission control scheme with service-differentiated call assignment is studied to gain insights on the effects of load sharing on interworking effectiveness. Then, the admission scheme is extended by using randomized call assignment to enable distributed implementation. Also, we analyze the impact of user mobility and data traffic variability. Further, an enhanced call assignment strategy is developed to exploit the heavy-tailedness of data call size. Last, the study is extended to a multi-service scenario. The overall resource utilization and QoS satisfaction are improved substantially by taking into account the multi-service traffic characteristics, such as the delay-sensitivity of voice traffic, elasticity and heavy-tailedness of data traffic, and rate-adaptiveness of video streaming traffic

Radio Resource Management for Wireless Mesh Networks Supporting Heterogeneous Traffic

Wireless mesh networking has emerged as a promising technology for future broadband wireless access, providing a viable and economical solution for both peer-to-peer applications and Internet access. The success of wireless mesh networks (WMNs) is highly contingent on effective radio resource management. In conventional wireless networks, system throughput is usually a common performance metric. However, next-generation broadband wireless access networks including WMNs are anticipated to support multimedia traffic (e.g., voice, video, and data traffic). With heterogeneous traffic, quality-of-service (QoS) provisioning and fairness support are also imperative. Recently, wireless mesh networking for suburban/rural residential areas has been attracting a plethora of attentions from industry and academia. With austere suburban and rural networking environments, multi-hop communications with decentralized resource allocation are preferred. In WMNs without powerful centralized control, simple yet effective resource allocation approaches are desired for the sake of system performance melioration. In this dissertation, we conduct a comprehensive research study on the topic of radio resource management for WMNs supporting multimedia traffic. In specific, this dissertation is intended to shed light on how to effectively and efficiently manage a WMN for suburban/rural residential areas, provide users with high-speed wireless access, support the QoS of multimedia applications, and improve spectrum utilization by means of novel radio resource allocation. As such, five important resource allocation problems for WMNs are addressed, and our research accomplishments are briefly outlined as follows: Firstly, we propose a novel node clustering algorithm with effective subcarrier allocation for WMNs. The proposed node clustering algorithm is QoS-aware, and the subcarrier allocation is optimality-driven and can be performed in a decentralized manner. Simulation results show that, compared to a conventional conflict-graph approach, our proposed approach effectively fosters frequency reuse, thereby improving system performance; Secondly, we propose three approaches for joint power-frequency-time resource allocation. Simulation results show that all of the proposed approaches are effective in provisioning packet-level QoS over their conventional resource allocation counterparts. Our proposed approaches are of low complexity, leading to preferred candidates for practical implementation; Thirdly, to further enhance system performance, we propose two low-complexity node cooperative resource allocation approaches for WMNs with partner selection/allocation. Simulation results show that, with beneficial node cooperation, both proposed approaches are promising in supporting QoS and elevating system throughput over their non-cooperative counterparts; Fourthly, to further utilize the temporarily available radio spectrum, we propose a simple channel sensing order for unlicensed secondary users. By sensing the channels according to the descending order of their achievable rates, we prove that a secondary user should stop at the first sensed free channel for the sake of optimality; and Lastly, we derive a unified optimization framework to effectively attain different degrees of performance tradeoff between throughput and fairness with QoS support. By introducing a bargaining floor, the optimal tradeoff curve between system throughput and fairness can be obtained by solving the proposed optimization problem iteratively