Qualidade de serviço em redes IEEE 802.16 com topologia em malha

Mestrado em Engenharia Electrónica e TelecomunicaçõesO IEEE 802.16 apresenta-se actualmente como a tecnologia mais avançada e aliciante para o acesso de banda larga metropolitano. A sua topologia pontomultiponto (PMP) foi desenvolvida desde o início com suporte para qualidade de serviço (QoS) gerida pelo controlador ou operador da rede, podendo assim complementar, as actuais soluções móveis de terceira geração. Por outro lado, a topologia opcional “em malha” (Mesh) permite a criação de redes autoconfiguráveis e com encaminhamento de tráfego através de vários pontos da rede. No entanto, as especificações e mecanismos de QoS apresentados na norma não são consistentes para estes dois modos de operação. Com a presente dissertação pretende-se estudar e avaliar uma arquitectura de QoS para o modo Mesh, baseada nos mecanismos delineados para a topologia PMP, permitindo a coexistência dos dois modos de operação. A arquitectura apresentada foca-se numa gestão eficiente da largura de banda utilizando mensagens de controlo ao nível MAC introduzidas pelo standard IEEE 802.16. Os resultados obtidos mostram a eficiência das classes de serviço implementadas, convergindo com os requisitos de QoS do modo PMP. ABSTRACT: The IEEE 802.16 standard is by now the most advanced and attractive technology for the metropolitan broadband access. The point-to-multipoint (PMP) topology was developed from the beginning with quality of service (QoS) support, managed by the network operator, thus complementing the existing third-generation mobile solutions. On the other hand, the alternative Mesh topology allows the creation of self-configuring networks with traffic routing through various nodes. However, the QoS specifications and mechanisms presented in the standard are not consistent for these two operation modes. The present work aims to study and evaluate a QoS architecture for the Mesh mode, based on mechanisms designed to PMP and thus allowing the coexistence of the two operation modes. The proposed architecture focuses on an efficient network bandwidth management, using control messages at the MAC level as suggested in the IEEE 802.16 standard. The results show the efficiency of the implemented service classes, coming to a convergence with the quality requirements announced by PMP mode

WiMAX Basics From Deployments to PHY Improvements

© ASEE 2014WiMAX (Worldwide Interoperability for Microwave Access) is an emerging broadband wireless technology for providing Last mile solutions for supporting higher bandwidth and multiple service classes with various quality of service requirement. The unique architecture of the WiMAX MAC and PHY layers that uses OFDMA to allocate multiple channels with different modulation schema and multiple time slots for each channel allows better adaptation of heterogeneous user’s requirements. The main architecture in WiMAX uses PMP (Point to Multipoint), Mesh mode or the new MMR (Mobile Multi hop Mode) deployments where scheduling and multicasting have different approaches. In PMP SS (Subscriber Station) connects directly to BS (Base Station) in a single hop route so channel conditions adaptations and supporting QoS for classes of services is the key points in scheduling, admission control or multicasting, while in Mesh networks SS connects to other SS Stations or to the BS in a multi hop routes, the MMR mode extends the PMP mode in which the SS connects to either a relay station (RS) or to Bs. Both MMR and Mesh uses centralized or distributed scheduling with multicasting schemas based on scheduling trees for routing. In this paper a broad study is conducted About WiMAX technology PMP and Mesh deployments from main physical layers features with differentiation of MAC layer features to scheduling and multicasting approaches in both modes of operations

Seamless Infrastructure independent Multi Homed NEMO Handoff Using Effective and Timely IEEE 802.21 MIH triggers

Handoff performance of NEMO BS protocol with existent improvement proposals is still not sufficient for real time and QoS-sensitive applications and further optimizations are needed. When dealing with single homed NEMO, handoff latency and packet loss become irreducible all optimizations included, so that it is impossible to meet requirements of the above applications. Then, How to combine the different Fast handoff approaches remains an open research issue and needs more investigation. In this paper, we propose a new Infrastructure independent handoff approach combining multihoming and intelligent Make-Before-Break Handoff. Based on required Handoff time estimation, L2 and L3 handoffs are initiated using effective and timely MIH triggers, reducing so the anticipation time and increasing the probability of prediction. We extend MIH services to provide tunnel establishment and switching before link break. Thus, the handoff is performed in background with no latency and no packet loss while pingpong scenario is almost avoided. In addition, our proposal saves cost and power consumption by optimizing the time of simultaneous use of multiple interfaces. We provide also NS2 simulation experiments identifying suitable parameter values used for estimation and validating the proposed mode

An architecture for IEEE 802.16 MAC scheduler design

Copyright © 2007 IEEEThe scheduling algorithm for IEEE 802.16 broadband wireless access system has been left open in the standard. In this paper, we consider three criteria that we have identified as important criteria for an 802.16 scheduler: Service Type differentiation, dynamic sub-frame partition and Subscriber Station differentiation. We investigate the scheduler design from a general perspective, based on these three criteria