365 research outputs found

    Achieving Frequency Reuse 1 in WiMAX Networks with Beamforming

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    In this chapter, we examine the performance of adaptive beamforming in connection with three different subcarrier permutation schemes (PUSC, FUSC and AMC) in WiMAX cellularnetwork with frequency reuse 1. Performance is evaluated in terms of radio quality parameters and system throughput. We show that organization of pilot subcarriers in PUSC Majorgroups has a pronounced effect on system performance while considering adaptive beamforming. Adaptive beamforming per PUSC group offers full resource utilization without need of coordination among base stations. Though FUSC is also a type of distributed subcarrier permutation, its performance in terms of outage probability is somewhat less than that of PUSC. We also show that because of lack of diversity, adjacent subcarrier permutation AMC has theleast performance as far as outage probability is concerned. Results in this chapter are based on Monte Carlo simulations performed in downlink.</p

    Quantifying Potential Energy Efficiency Gain in Green Cellular Wireless Networks

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    Conventional cellular wireless networks were designed with the purpose of providing high throughput for the user and high capacity for the service provider, without any provisions of energy efficiency. As a result, these networks have an enormous Carbon footprint. In this paper, we describe the sources of the inefficiencies in such networks. First we present results of the studies on how much Carbon footprint such networks generate. We also discuss how much more mobile traffic is expected to increase so that this Carbon footprint will even increase tremendously more. We then discuss specific sources of inefficiency and potential sources of improvement at the physical layer as well as at higher layers of the communication protocol hierarchy. In particular, considering that most of the energy inefficiency in cellular wireless networks is at the base stations, we discuss multi-tier networks and point to the potential of exploiting mobility patterns in order to use base station energy judiciously. We then investigate potential methods to reduce this inefficiency and quantify their individual contributions. By a consideration of the combination of all potential gains, we conclude that an improvement in energy consumption in cellular wireless networks by two orders of magnitude, or even more, is possible.Comment: arXiv admin note: text overlap with arXiv:1210.843

    Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things: Key Technologies, Opportunities, and Challenges

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    With the rapid development of marine activities, there has been an increasing number of maritime mobile terminals, as well as a growing demand for high-speed and ultra-reliable maritime communications to keep them connected. Traditionally, the maritime Internet of Things (IoT) is enabled by maritime satellites. However, satellites are seriously restricted by their high latency and relatively low data rate. As an alternative, shore & island-based base stations (BSs) can be built to extend the coverage of terrestrial networks using fourth-generation (4G), fifth-generation (5G), and beyond 5G services. Unmanned aerial vehicles can also be exploited to serve as aerial maritime BSs. Despite of all these approaches, there are still open issues for an efficient maritime communication network (MCN). For example, due to the complicated electromagnetic propagation environment, the limited geometrically available BS sites, and rigorous service demands from mission-critical applications, conventional communication and networking theories and methods should be tailored for maritime scenarios. Towards this end, we provide a survey on the demand for maritime communications, the state-of-the-art MCNs, and key technologies for enhancing transmission efficiency, extending network coverage, and provisioning maritime-specific services. Future challenges in developing an environment-aware, service-driven, and integrated satellite-air-ground MCN to be smart enough to utilize external auxiliary information, e.g., sea state and atmosphere conditions, are also discussed

    Development of Interference Mitigation Schemes in 4G Technology Using Smart Antennas

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    With the increase in demand of mobile users and high speed data requirements, the world is now migrating towards 4G. this has led to increase in Co-Channel interference and multipath in urban/dense urban environment by which the network capacity has been reduced. Hence there is a necessity of developing new schemes and methods which can optimally exploit the limited resources and minimize the interference for higher user capacity and qualitative wireless communication. Smart Antenna has now come to the rescue of the changing trends in wireless communication. It efficiently reduces the effect of CCI and Multipath by adapting the antenna pattern to track and locate the desired user while eliminating the undesired ones. So this project aims in modelling, analysis and simulation of an efficient smart antenna system by studying and comparing various weight updating algorithms of Direction of Arrival (DOA) like MUSIC algorithm and ESPRIT algorithm and adaptive beam forming algorithms like Least Mean Square algorithm, Sample Matrix Inversion algorithm and Conjugate Gradient Method Algorithm choosing the most efficient ones for the system desig
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