rtPS uplink scheduling algorithms for IEEE 802.16 networks

IEEE 802.16 MAC provides flexible bandwidth allocation and QoS mechanisms for users with different requirements. However, QoS scheduling is not specified by the 802.16 standard and is thus left open for vendors' implementation. In this paper, we propose an uplink scheduler to be used in WiMAX Base Station (BS) for rtPS type of connections. We propose that the base station maintains a leaky bucket for each rtPS connection to police and schedule rtPS traffic for uplink traffic management. The proposed scheduler is studied via simulations in MATLAB and throughput and fairness properties of the scheduler are demonstrated. Copyright ©2008 by Boǧaziçi University

A Survey on Scheduling in IEEE 802.16 Mesh Mode

Cataloged from PDF version of article.IEEE 802.16 standard (also known as WiMAX) defines the wireless broadband network technology which aims to solve the so called last mile problem via providing high bandwidth Internet even to the rural areas for which the cable deployment is very costly. The standard mainly focuses on the MAC and PHY layer issues, supporting two transmission modes: PMP (Point-to-Multipoint) and mesh modes. Mesh mode is an optional mode developed as an extension to PMP mode and it has the advantage of having an improving performance as more subscribers are added to the system using multi-hop routes. In 802.16 MAC protocol, mesh mode slot allocation and reservation mechanisms are left open which makes this topic a hot research area. Hence, the focus of this survey will mostly be on the mesh mode, and the proposed scheduling algorithms and performance evaluation methods

Performance analysis of diversity techniques for OFDM and base station cooperation

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Science of Bilkent University, 2010.Thesis (Master's) -- Bilkent University, 2010.Includes bibliographical references leaves 76-80.The main goal of the next generation wireless communication systems is to provide high data rate services. In order to deal with performance-limiting challenges that include frequency selective fading channels, power and bandwidth constraints, multiple input multiple output (MIMO) and orthogonal frequency division multiplexing (OFDM) techniques have been proposed as effective techniques to combat fading and to provide high rate reliable transmission. In this thesis we first give an overview of WiMAX as an example of an OFDM system and study the performance of the WiMAX physical layer under different MIMO techniques. We also analyze space-frequency coding and propose a threaded algebraic space-time (TAST) based code. Secondly, since the mobile bandwidth is an expensive and scarce resource, it seems likely that a high frequency reuse will be employed in the future cellular networks to increase spectral efficiency. This means that base stations (BSs) will operate in the same frequency band and therefore cause cochannel interference (CCI) to the users at other cells. CCI is an important performance degrading factor. Therefore our second aim is to investigate BS cooperation techniques to mitigate CCI. We assume that channel state information (CSI) is available at the cooperating BSs and analyze the performance gains due to cooperation when used in conjunction with Alamouti space-time coding.Üzeler, HandeM.S

Uplink scheduling algorithms for the rtPS traffic class for IEEE 80216 networks

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent University, 2008.Thesis (Master's) -- Bilkent University, 2008.Includes bibliographical references leaves 83-86.IEEE 802.16 MAC provides extensive bandwidth allocation and QoS mechanisms for various types of applications. However, the scheduling mechanisms for the uplink and downlink are unspecified by the IEEE 802.16 standard and are thus left open for vendors’ own implementations. Ensuring QoS requirements at the MAC level for different users with different QoS requirements and traffic profiles is also another challenging problem in the area. The standard defines five different scheduling services one of them being the real-time Polling Service (rtPS). In this thesis, we propose an uplink scheduler to be implemented on the WiMAX Base Station (BS) for rtPS type connections. We propose that the base station maintains a leaky bucket for each rtPS connection to police and schedule rtPS traffic for uplink traffic management. There are two scheduling algorithms defined in this study: one is based on a simpler round robin scheme using leaky buckets for QoS management, whereas the other one uses again leaky buckets for QoS management but also a proportional fair scheme for potential throughput improvement in case of varying channel conditions. The proposed two schedulers are studied via simulations using MATLAB to demonstrate their performance in terms of throughput, fairness and delay. We show that the leaky bucket based scheduler ensures the QoS commitments of each user in terms of a minimum bandwidth guarantee whereas the proportional fair algorithm is shown to opportunistically take advantage of varying channel conditions.Ertürk, Mustafa CenkM.S

WIMAX 802.16 PHYSICAL LAYER IMPLEMENTATION AND WIMAX COVERAGE AND PLANNING.

Over the last decade, the impact of wireless communication on the way we live and carry out business has been surpassed only by impact of the internet. But wireless communications is still in its infancy and the next stage of its development will be supplementing or replacing network infrastructure that was traditionally wired. The advent and adoption of the computer and the myriad software packages available for it offered the ability to generate a new wave of communication combining art, pictures, music and words into a targeted multimedia presentation. These presentations are large so that is requires higher bandwidth transmission facilities. Coupling this with the need for mobility, the solution would be wireless data delivery putting in consideration the bandwidth request. WiMAX technology is based on the IEEE 802.16 standard, it was only recently when the first IEEE 802.16 based equipment broadband began to enter the market. The additional spectrum, bandwidth and throughout capabilities of 802.16 will remarkably improve wireless data delivery and should allows even more wireless data service areas to be deployed economically. In this Final Year Project, a study about the IEEE 802.16 standard and mainly concentrate on the 802.16 PHY Layer behaviors was performed. A Simulink based model for the 802.16 PHY Layer was built for simulation and performance evaluation of WiMAX. MATLA

Assessment and Real Time Implementation of Wireless Communications Systems and Applications in Transportation Systems

Programa Oficial de Doutoramento en Tecnoloxías da Información e das Comunicacións en Redes Móbiles. 5029V01[Resumo] Os sistemas de comunicación sen fíos de cuarta e quinta xeración (4G e 5G) utilizan unha capa física (PHY) baseada en modulacións multiportadora para a transmisión de datos cun gran ancho de banda. Este tipo de modulacións proporcionan unha alta eficiencia espectral á vez que permiten corrixir de forma sinxela os efectos da canle radio. Estes sistemas utilizan OFDMA como mecanismo para a repartición dos recursos radio dispoñibles entre os diferentes usuarios. Este repartimento realízase asignando un subconxunto de subportadoras a cada usuario nun instante de tempo determinado. Isto aporta unha gran flexibilidade ó sistema que lle permite adaptarse tanto ós requisitos de calidade de servizo dos usuarios como ó estado da canle radio. A capa de acceso ó medio (MAC) destes sistemas encárgase de configurar os diversos parámetros proporcionados pola capa física OFDMA, ademais de xestionar os diversos fluxos de información de cada usuario, transformando os paquetes de capas superiores en paquetes da capa física. Neste traballo estúdase o deseño e implementación das capas MAC e PHY de sistemas de comunicación 4G ademais da súa aplicabilidade en sistemas de transporte ferroviarios. Por unha parte, abórdase o deseño e implementación en tempo real do estándar WiMAX. Estúdanse os mecanismos necesarios para establecer comunicacións bidireccionais entre unha estación base e múltiples dispositivos móbiles. Ademais, estúdase como realizar esta implementación nunha arquitectura hardware baseada en DSPs e FPGAs, na que se implementan as capas MAC e PHY. Dado que esta arquitectura ten uns recursos computacionais limitados, tamén se estudan as necesidades de cada módulo do sistema para poder garantir o funcionamento en tempo real do sistema completo. Por outra parte, tamén se estuda a aplicabilidade dos sistemas 4G a sistemas de transporte públicos. Os sistemas de comunicacións e sinalización son unha parte vital para os sistemas de transporte ferroviario e metro. As comunicacións sen fíos utilizadas por estes sistemas deben ser robustas e proporcionar unha alta fiabilidade para permitir a supervisión, control e seguridade do tráfico ferroviario. Para levar a cabo esta avaliación de viabilidade realízanse simulacións de redes de comunicacións LTE en contornos de transporte ferroviarios, comprobando o cumprimento dos requisitos de fiabilidade e seguridade. Realízanse diferentes simulacións do sistema de comunicacións para poder ser avaliadas e seleccionar a configuración e arquitectura do sistema máis axeitada en función do escenario considerado. Tamén se efectúan simulacións de redes baseadas en Wi-Fi, dado que é a solución máis utilizada nos metros, para confrontar os resultados cos obtidos para LTE. Para que os resultados das simulacións sexan realistas débense empregar modelos de propagación radio axeitados. Nas simulacións utilízanse tanto modelos deterministas como modelos baseados nos resultados de campañas de medida realizadas nestes escenarios. Nas simulacións empréganse os diferentes fluxos de información destes escenarios para comprobar que se cumpren os requisitos de calidade de servicio (QoS). Por exemplo, os fluxos críticos para o control ferroviario, como European Train Control System (ETCS) ou Communication-Based Train Control (CBTC), necesitan unha alta fiabilidade e un retardo mínimo nas comunicacións para garantir o correcto funcionamento do sistema.[Resumen] Los sistemas de comunicación inalámbricos de cuarta y quinta generación (4G y 5G) utilizan una capa física (PHY) basada en modulaciones multiportadora para la transmisión de datos con un gran ancho de banda. Este tipo de modulaciones han demostrado tener una alta eficiencia espectral a la vez que permiten corregir de forma sencilla los efectos del canal radio. Estos sistemas utilizan OFDMA como mecanismo para el reparto de los recursos radio disponibles entre los diferentes usuarios. Este reparto se realiza asignando un subconjunto de subportadoras a cada usuario en un instante de tiempo determinado. Esto aporta una gran flexibilidad al sistema que le permite adaptarse tanto a los requisitos de calidad de servicio de los usuarios como al estado del canal radio. La capa de acceso al medio (MAC) de estos sistemas se encarga de configurar los diversos parámetros proporcionados por la capa física OFDMA, además de gestionar los diversos flujos de información de cada usuario, transformando los paquetes de capas superiores en paquetes de la capa física. En este trabajo se estudia el diseño e implementación de las capas MAC y PHY de sistemas de comunicación 4G además de su aplicabilidad en sistemas de transporte ferroviarios. Por una parte, se aborda el diseño e implementación en tiempo real del estándar WiMAX. Se estudian los mecanismos necesarios para establecer comunicaciones bidireccionales entre una estación base y múltiples dispositivos móviles. Además, se estudia cómo realizar esta implementación en una arquitectura hardware basada en DSPs y FPGAs, en la que se implementan las capas MAC y PHY. Dado que esta arquitectura tiene unos recursos computacionales limitados, también se estudian las necesidades de cada módulo del sistema para poder garantizar el funcionamiento en tiempo real del sistema completo. Por otra parte, también se estudia la aplicabilidad de los sistemas 4G a sistemas de transporte públicos. Los sistemas de comunicaciones y señalización son una parte vital para los sistemas de transporte ferroviario y metro. Las comunicaciones inalámbricas utilizadas por estos sistemas deben ser robustas y proporcionar una alta fiabilidad para permitir la supervisión, control y seguridad del tráfico ferroviario. Para llevar a cabo esta evaluación de viabilidad se realizan simulaciones de redes de comunicaciones LTE en entornos de transporte ferroviarios, comprobando si se cumplen los requisitos de fiabilidad y seguridad. Se realizan diferentes simulaciones del sistema de comunicaciones para poder ser evaluados y seleccionar la configuración y arquitectura del sistema más adecuada en función del escenario planteado. También se efectúan simulaciones de redes basadas en Wi-Fi, dado que es la solución más utilizada en los metros, para comparar los resultados con los obtenidos para LTE. Para que los resultados de las simulaciones sean realistas se deben utilizar modelos de propagación radio apropiados. En las simulaciones se utilizan tanto modelos deterministas como modelos basados en los resultados de campañas de medida realizadas en estos escenarios. En las simulaciones se utilizan los diferentes flujos de información de estos escenarios para comprobar que se cumplen sus requisitos de calidad de servicio. Por ejemplo, los flujos críticos para el control ferroviario, como European Train Control System (ETCS) o Communication-Based Train Control (CBTC), necesitan una alta fiabilidad y un retardo bajo en las comunicaciones para garantizar el correcto funcionamiento del sistema.[Abstract] The fourth and fifth generation wireless communication systems (4G and 5G) use a physical layer (PHY) based on multicarrier modulations for data transmission using high bandwidth. This type of modulations has shown to provide high spectral efficiency while allowing low complexity radio channel equalization. These systems use OFDMA as a mechanism for distributing the available radio resources among different users. This allocation is done by assigning a subset of subcarriers to each user in a given instant of time. This provides great flexibility to the system that allows it to adapt to both the quality of service requirements of users and the radio channel state. The media access layer (MAC) of these systems is in charge of configuring the multiple OFDMA PHY layer parameters, in addition to managing the data flows of each user, transforming the higher layer packets into PHY layer packets. This work studies the design and implementation of MAC and PHY layers of 4G communication systems as well as their applicability in rail transport systems. On the one hand, the design and implementation in real time of the WiMAX standard is addressed. The required mechanisms to establish bidirectional communications between a base station and several mobile devices are also evaluated. Moreover, a MAC layer and PHY layer implementation is presented, using a hardware architecture based in DSPs and FPGAs. Since this architecture has limited computational resources, the requirements of each processing block of the system are also studied in order to guarantee the real time operation of the complete system. On the other hand, the applicability of 4G systems to public transportation systems is also studied. Communications and signaling systems are a vital part of rail and metro transport systems. The wireless communications used by these systems must be robust and provide high reliability to enable the supervision, control and safety of rail traffic. To carry out this feasibility assessment, LTE communications network simulations are performed in rail transport environments to verify that reliability and safety requirements are met. Several simulations are carried out in order to evaluate the system performance and select the most appropriate system configuration in each case. Simulations of Wi-Fi based networks are also carried out, since it is the most used solution in subways, to compare the results with those obtained for LTE. To perform the simulations correctly, appropriate radio propagation models must be used. Both deterministic models and models based on the results of measurement campaigns in these scenarios are used in the simulations. The simulations use the different information flows present in the railway transportation systems to verify that its quality of service requirements are met. For example, critical flows for railway control, such as the European Train Control System (ETCS) or Communication-Based Train Control (CBTC), require high reliability and low delay communications to ensure the proper functioning of the system

WiMAX for Smart Grid Applications and the Influence of Impulsive Noise

In order to adapt the power grid to today’s level of electricity consumption, growing investments are made in a smart power grid. The employment of this novel architecture brings advantages such as efficiency of energy production and consumption, availability and reliability of the service, scalability, self-healing grid, environment friendly, consumer participation in electricity production with harvested energy through solar panels and wind turbines. The rising power demand curve can be restrained by a smart implementation of the new electrical power grid. The smart grid brings out an additional layer that will interconnect and manage all the generation, transmission and distribution sectors of the power grid. Many other features will be brought by the smart grid that will improve its reliability and efficiency and will lead towards renewable and sustainable energy development. In this thesis, we analyze the performances of a smart grid in which the communication layer is implemented using Worldwide Interoperability for Microwave Access (WiMAX) communication technology. Parameters such as throughput, network capacity, packet loss, latency are studied by analyzing the traffic model generated by using several applications in the Distribution Area Network (DAN) of the Smart Grid. The applications whose traffic was simulated using OPNET are the following four: metering and pricing, electrical car, video surveillance and voice support for workforce. The capacity of a base station in the distribution area network is obtained for each smart grid application individually as well as for the combined traffic of all applications. Furthermore, this thesis also discusses the effects of the impulsive noise over the communication layer. An Orthogonal Frequency Division Multiplexing (OFDM) structure using WiMAX physical layer characteristics was simulated with and without the influence of impulsive noise using MATLAB. The results highlighted the effects of the impulsive noise over performances such as bit error rate, packet error rate, throughput and the overall capacity of the network. For a better understanding, the outcomes are presented with and without the presence of impulsive noise