88 research outputs found

    Cell sectoring for CDMA cellular systems.

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    Shen Fangzhong.Thesis (M.Phil.)--Chinese University of Hong Kong, 2002.Includes bibliographical references (leaves 55-57).Abstracts in English and Chinese.Abstract --- p.iAcknowledgements --- p.iiiList of Figures --- p.viList of Tables --- p.ixChapter Chapter 1. --- Introduction --- p.1Chapter 1.1. --- Motivation --- p.1Chapter 1.2. --- Related Work --- p.2Chapter 1.3. --- Our Work --- p.2Chapter 1.4. --- Some Assumptions --- p.2Chapter 1.4.1. --- Beamforming --- p.2Chapter 1.4.2. --- Downlink Channel --- p.2Chapter 1.4.3. --- Single Cell --- p.3Chapter 1.5. --- Thesis Road Map --- p.3Chapter Chapter 2. --- Preliminaries of Cell Sectoring --- p.4Chapter 2.1. --- Introduction --- p.4Chapter 2.2. --- Beamforming --- p.4Chapter 2.2.1. --- Linear Array --- p.5Chapter 2.2.2. --- Circular Array --- p.8Chapter 2.2.3. --- Butler Beamforming Network --- p.9Chapter 2.2.4. --- Dynamic Beamforming --- p.10Chapter 2.3. --- Power Control --- p.16Chapter Chapter 3. --- Dynamic Cell Sectoring --- p.19Chapter 3.1. --- Introduction --- p.19Chapter 3.2. --- Minimum Total Transmission Power sectoring --- p.21Chapter 3.2.1. --- Problem Statement --- p.21Chapter 3.2.2. --- Shortest Path Problem Formulation --- p.23Chapter 3.2.3. --- Shortest Path Algorithm and Complexity --- p.26Chapter 3.2.4. --- Graph Reduction --- p.28Chapter 3.2.5. --- Example --- p.30Chapter 3.3. --- Power Equalization Sectoring --- p.33Chapter 3.3.1. --- Relationship Between MinTTP Sectoring and PE Sectoring --- p.33Chapter 3.3.2. --- Power Equalization Sectoring Algorithm --- p.36Chapter 3.4. --- Numerical Results --- p.37Appendix --- p.44Chapter Chapter 4. --- Resectoring Algorithms --- p.46Chapter 4.1. --- Introduction --- p.46Chapter 4.2. --- Nyquist Sampling Theorem --- p.47Chapter 4.3. --- MinTTP Resectoring --- p.47Chapter 4.4. --- PE Resectoring --- p.43Chapter 4.5. --- Handoff --- p.48Chapter 4.5.1. --- Handoff Load --- p.49Chapter 4.6. --- Performance --- p.49Chapter Chapter 5. --- Conclusion and Future Work --- p.53Chapter 5.1. --- Thesis Summary --- p.53Chapter 5.2. --- Future Work --- p.54Bibliography --- p.5

    Robust Schemes to Enhance Energy Consumption Efficiency for Millimeter Wave-Based Microcellular Network in Congested Urban Environments

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    Future wireless communication networks will be largely characterized by small cell deployments, typically on the order of 200 meters of radius/cell, at most. Meanwhile, recent studies show that base stations (BS) account for about 80 to 95 % of the total network power. This simply implies that more energy will be consumed in the future wireless network since small cell means massive deployment of BS. This phenomenon makes energy-efficient (EE) control a central issue of critical consideration in the design of future wireless networks. This paper proposes and investigates (the performance of) two different energy-saving approaches namely, adaptive-sleep sectorization (AS), adaptive hybrid partitioning schemes (AH) for small cellular networks using smart antenna technique. We formulated a generic base-model for the above-mentioned schemes and applied the spatial Poisson process to reduce the system complexity and to improve flexibility in the beam angle reconfiguration of the adaptive antenna, also known as a smart antenna (SA). The SA uses the scalable algorithms to track active users in different segments/sectors of the microcell, making the proposed schemes capable of targeting specific users or groups of users in periods of sparse traffic, and capable of performing optimally when the network is highly congested. The capabilities of the proposed smart/adaptive antenna approaches can be easily adapted and integrated into the massive MIMO for future deployment. Rigorous numerical analysis at different orders of sectorization shows that among the proposed schemes, the AH strategy outperforms the AS in terms of energy saving by about 52 %. Generally, the proposed schemes have demonstrated the ability to significantly increase the power consumption efficiency of micro base stations for future generation cellular systems, over the traditional design methodologies

    A survey of self organisation in future cellular networks

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    This article surveys the literature over the period of the last decade on the emerging field of self organisation as applied to wireless cellular communication networks. Self organisation has been extensively studied and applied in adhoc networks, wireless sensor networks and autonomic computer networks; however in the context of wireless cellular networks, this is the first attempt to put in perspective the various efforts in form of a tutorial/survey. We provide a comprehensive survey of the existing literature, projects and standards in self organising cellular networks. Additionally, we also aim to present a clear understanding of this active research area, identifying a clear taxonomy and guidelines for design of self organising mechanisms. We compare strength and weakness of existing solutions and highlight the key research areas for further development. This paper serves as a guide and a starting point for anyone willing to delve into research on self organisation in wireless cellular communication networks

    Planning for Small Cells in a Cellular Network

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    In this thesis, we analyze the effect of deploying small cells on the performance of a network comprising several macro cells. We identify potential locations for low-power base-stations based on the coverage patterns of the macro cells and propose three schemes for placing the small cells. We show that by judiciously installing just two small cells for every macro base-station at these locations and allocating separate resources to all the small cells on a global level, we can increase the performance of the network significantly (~ 45%). An added benefit of our schemes is that we can switch o the macro base-stations at night (when the number of active users is low) and significantly reduce their operation cost.4 month

    Advanced array processing techniques and systems

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    Research and development on smart antennas, which are recognized as a promising technique to improve the performance of mobile communications, have been extensive in the recent years. Smart antennas combine multiple antenna elements with a signal processing capability in both space and time to optimize its radiation and reception pattern automatically in response to the signal environment. This paper concentrates on the signal processing aspects of smart antenna systems. Smart antennas are often classified as either switched-beam or adaptive-array systems, for which a variety of algorithms have been developed to enhance the signal of interest and reject the interference. The antenna systems need to differentiate the desired signal from the interference, and normally requires either a priori knowledge or the signal direction to achieve its goal. There exists a variety of methods for direction of arrival (DOA) estimation with conflicting demands of accuracy and computation. Similarly, there are many algorithms to compute array weights to direct the maximum radiation of the array pattern toward the signal and place nulls toward the interference, each with its convergence property and computational complexity. This paper discusses some of the typical algorithms for DOA estimation and beamforming. The concept and details of each algorithm are provided. Smart antennas can significantly help in improving the performance of communication systems by increasing channel capacity and spectrum efficiency, extending range coverage, multiplexing channels with spatial division multiple access (SDMA), and compensating electronically for aperture distortion. They also reduce delay spread, multipath fading, co-channel interference, system complexity, bit error rates, and outage probability. In addition, smart antennas can locate mobile units or assist the location determination through DOA and range estimation. This capability can support and benefit many location-based services including emergency assistance, tracking services, safety services, billing services, and information services such as navigation, weather, traffic, and directory assistance

    Principles of Mobile Communication

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    Performance Analysis of Joint Base-Station Multiantenna Multibeam and Channel Assignment Scheme for Hierarchical Cellular System

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    Different from the traditional configuration of hierarchical cellular, we introduce the joint base-station multi-antenna multi-beam and channel assignment scheme for hierarchical cellular in this paper. The proposed scheme is based on multi-beam base-station antenna splitting in the elevation-radiating plane, and a dynamic channel allocation scheme by combining the adaptive antenna technologies. Simulation results show that the proposed configuration of the hierarchical cellular can enhance the spectral efficiency remarkably
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