1,005 research outputs found

    ADAPTIVE RESOURCE ALLOCATION FOR WIRELESS MULTICAST MIMO-OFDM SYSTEMS

    Get PDF
    Multiple antenna orthogonal frequency division multiple access (OFDMA) is a promissing technique for the high downlink capacity in the next generation wireless systems, in which adaptive resource allocation would be an important research issue that can significantly improve the performance with guaranteed QoS for users. Moreover, most of the current source allocation algorithms are limited to the unicast system. In this paper, dynamic resource allocation is studied for multiple antenna OFDMA based systems which provide multicast service. The performance of multicast system is simulated and compared with that of the unicast system. Numerical results also show that the propossed algorithms improve the system capacity significantly compared with the conventional scheme

    Video QoS/QoE over IEEE802.11n/ac: A Contemporary Survey

    Get PDF
    The demand for video applications over wireless networks has tremendously increased, and IEEE 802.11 standards have provided higher support for video transmission. However, providing Quality of Service (QoS) and Quality of Experience (QoE) for video over WLAN is still a challenge due to the error sensitivity of compressed video and dynamic channels. This thesis presents a contemporary survey study on video QoS/QoE over WLAN issues and solutions. The objective of the study is to provide an overview of the issues by conducting a background study on the video codecs and their features and characteristics, followed by studying QoS and QoE support in IEEE 802.11 standards. Since IEEE 802.11n is the current standard that is mostly deployed worldwide and IEEE 802.11ac is the upcoming standard, this survey study aims to investigate the most recent video QoS/QoE solutions based on these two standards. The solutions are divided into two broad categories, academic solutions, and vendor solutions. Academic solutions are mostly based on three main layers, namely Application, Media Access Control (MAC) and Physical (PHY) which are further divided into two major categories, single-layer solutions, and cross-layer solutions. Single-layer solutions are those which focus on a single layer to enhance the video transmission performance over WLAN. Cross-layer solutions involve two or more layers to provide a single QoS solution for video over WLAN. This thesis has also presented and technically analyzed QoS solutions by three popular vendors. This thesis concludes that single-layer solutions are not directly related to video QoS/QoE, and cross-layer solutions are performing better than single-layer solutions, but they are much more complicated and not easy to be implemented. Most vendors rely on their network infrastructure to provide QoS for multimedia applications. They have their techniques and mechanisms, but the concept of providing QoS/QoE for video is almost the same because they are using the same standards and rely on Wi-Fi Multimedia (WMM) to provide QoS

    Multicast Scheduling and Resource Allocation Algorithms for OFDMA-Based Systems: A Survey

    Get PDF
    Multicasting is emerging as an enabling technology for multimedia transmissions over wireless networks to support several groups of users with flexible quality of service (QoS)requirements. Although multicast has huge potential to push the limits of next generation communication systems; it is however one of the most challenging issues currently being addressed. In this survey, we explain multicast group formation and various forms of group rate determination approaches. We also provide a systematic review of recent channel-aware multicast scheduling and resource allocation (MSRA) techniques proposed for downlink multicast services in OFDMA based systems. We study these enabling algorithms, evaluate their core characteristics, limitations and classify them using multidimensional matrix. We cohesively review the algorithms in terms of their throughput maximization, fairness considerations, performance complexities, multi-antenna support, optimality and simplifying assumptions. We discuss existing standards employing multicasting and further highlight some potential research opportunities in multicast systems

    Capacity Behaviour using WSDV Scheme over WiMAX

    Get PDF
    The objective of this project is to create Mobile Worldwide Interoperability for Microwave Access (WiMAX) for 4th generation mobile wireless networks in which it is foreseen that mobile Television (TV) services will reproduce rapidly. In television applications are bandwidth hogs that cause a challenging capacity problem in wireless networks. To address this challenge, a novel scheme for mobile Television services over WiMAX network, called the Wireless Switched Digital Video (WSDV) scheme, is proposed. Compared with the conventional broadcast or unicast schemes, the hybrid approach introduced in the proposed WSDV approach exploits the merits of two conventional schemes and mitigates their demerits, which enables it to increase wireless capacity for mobile Television services. The analytical model can capture the details of WiMAX resource allocation and take into consideration the popularity of the mobile Television contents being viewed by users enabling it to provide an accurate estimate of the amount of bandwidth required for WiMAX TV services and also enabling a designer to optimally select the number of channels via the WSDV service while meeting a desired level of blocking probability. The proposed optimized scheme outperforms the conventional schemes with respect to blocking probability. Finally, an end-to-end solution to the WSDV scheme is also presented
    • …
    corecore