An improved resource allocation scheme for WiMAX using channel information

In recent years, tremendous progress has been made in wireless communication systems to provide wireless coverage to end users at different data rates. WiMAX technology provides wireless broadband access over an extended coverage area in both fixed and mobility environments. Most of the existing resource allocation schemes allocate resources based on respective service class of the incoming users’ requests. However, due to variation in channel conditions, user mobility and diverse resource requirements QoS based resource allocation either results in over or under utilization of allocated resources. Therefore, resource allocation is a challenging task in WiMAX. This research proposes an improved resource management mechanism that performs resource allocation by taking into consideration not only the user service class but also the respective channel status. Based on these two parameters, this research aims to achieve improved resource allocation in terms of resource utilization, fairness and network throughput. First, a Channel Based Resource Allocation scheme is introduced where priority in resource allocation is given to users’ requests with relatively higher service classes and better channel status. To maintain fairness in resource allocation process, a Fair Resource Allocation Based Service mechanism is developed where priority is given to users’ requests having less additional resources demand. Finally, to improve throughput of the network, a Channel Based Throughput Improvement approach is proposed which dynamically selects a threshold level of channel gain based on individual channel gain of users. During resource allocation process, users above the threshold level are selected for resource allocation such that priority is given to users with high channel gain. Different simulation scenario results reveal an overall improved resource utilization from 87% to 91% and the throughput improves up to 15% when compared to existing schemes. In conclusion the performance of resource utilization is improved if channel status is considered as an input parameter

Mechanisms for quality of service provision in IEEE 802.16 networks

Orientador: Nelson Luis Saldanha da FonsecaTese (doutorado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: O padrão IEEE 802.16 para acesso sem fio em banda larga, também conhecido como WiMAX (Worldwide Interoperability for Microwave Access Forum), é uma solução de baixo custo para o acesso à Internet em áreas metropolitanas e rurais. Outro atrativo desta tecnologia está no fato de incluir uma arquitetura para provisão de Qualidade de Serviço (QoS) para aplicações de tempo real e aplicações que demandam altas taxas de transmissão. Esta arquitetura de QoS inclui um mecanismo de sinalização entre a estação base e as estações cliente, cinco níveis de serviço, para priorização e diferenciação do tráfego, um mecanismo de escalonamento e um mecanismo de controle de admissão de novas conexões. Entretanto, as políticas que devem ser utilizadas na implementação dos mecanismos de escalonamento e controle de admissão não foram definidas pelo padrão. O mecanismo de escalonamento tem como objetivo garantir a banda passante requisitada pelas estações cliente bem como promover o uso eficiente do enlace sem fio, equanto o mecanismo de controle de admissão restringe o número de conexões simultaneamente presentes na rede, de forma a evitar a saturação do enlace sem fio e, conseqüentemente, a violação dos requisitos de QoS. Esta tese propõe políticas para os mecanismos de escalonamento e de controle de admissão para a provisão de QoS em redes baseadas no padrão IEEE 802.16. A política de escalonamento proposta nesta tese é compatível com as especificações do padrão IEEE 802.16 e é capaz de atender os cinco tipos de serviço bem como o conjunto de parâmetros de QoS a eles associado. Requisitos de latência máxima e taxa mínima são garantidos para cada conexão aceita na rede, sem que os limites impostos pelos requisitos de taxa máxima e tamanho máximo da rajada sejam violados. Cinco soluções são propostas para o mecanismo de controle de admissão. Estas soluções visam atingir três objetivos principais: restringir o número de conexões simultaneamente presentes na rede para que o escalonador tenha recursos suficientes para atender os requisitos de QoS de cada conexão, atender as expectativas do provedor de serviço através da maximização do lucro e maximizar a satisfação dos usuários através da disponibilização de recursos extras. As soluções propostas foram avaliadas através de experimentos de simulação, utilizando um módulo para simulação de redes IEEE 802.16 desenvolvido para conduzir esta pesquisaAbstract: The IEEE 802.16 standard for broadband wireless access, also known as WiMAX (Worldwide Interoperability for Microwave Access Forum), is a low cost solution for Internet access in metropolitan and rural areas. Another advantage of this technology is the fact that it includes an architecture for the provision of Quality of Service (QoS) for real time and bandwidth demanding applications. This QoS architecture includes a signaling mechanism between base station and subcriber stations, five types of service, for traffic priorization and differentiation, a scheduling mechanism and a connection admission control mechanism. However, policies for the implementation of these mechanisms are not defined by the standard. The scheduling mechanism aims at guaranteeing the bandwidth required by the subscriber stations as well as enabling the efficient wireless link usage, while the connection admission control restricts the number of users simultaneously present in the network so as to avoid the wireless link saturation and, consequently, violation of QoS contracts. This theses proposes policies for scheduling and connection admission control mechanisms for the provision of QoS in IEEE 802.16 networks. The proposed scheduling policy is standard compliant and supports the five types of service as well as the QoS parameters associated with them. Maximum latency and minimum rate requirements are guaranteed without violating maximum rate and maximum traffic burst requirements. Five solutions are proposed for the connection admission control mechanism. These solutions aim to support three main goals: to restrict the number of simultaneous connections in the system so that the resources available to the scheduler are sufficient to guarantee the QoS requirements of each connection, to support the service provider expectations by maximizing the revenue, and to maximize the users satisfaction by providing extra resources. The proposed solutions were evaluated through simulation experiments using a module for the simulation of IEEE 802.16 networks developed to conduct this researchDoutoradoRedes de ComputadoresDoutor em Ciência da Computaçã