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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
111

Twenty-First Century Live Play - Recent Developments

Reid, Robert J., Callaghan, Nancy 10 1900 (has links)
International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / The 21st Century Live Play (21CLP) program is developing a mobile, low cost, wireless networking system that supports applications to provide a number of services for military use. 21CLP is a joint Defense Advanced Research Projects Agency (DARPA) and Central Test and Evaluation Investment Program (CTEIP) project. The Naval Undersea Warfare Center, Division Newport (NUWCDIVNPT), Code 382 has been assigned as the program manager for a T&E version of the 21CLP system. The 21CLP vision is a common instrumentation function that links, in real-time, live land, air and maritime entities together with a virtual battlespace in any location where forces are deployed or being trained, weapons systems are being tested and evaluated, and ultimately where missions are being conducted. This vision will be realized with an embedded, mobile, distributed, untethered system that requires little or no site preparation.
112

A Modular Scheme to Detect and Combat Sinusoidal Variation in Fading Channels

Sastry, Sushruth, Kosbar, Kurt 10 1900 (has links)
ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV / Fading estimation in wireless communication systems depend on an expected fading model and assumptions about the channel itself. The bit error rate (BER) performance of the communication system is affected by how closely the assumptions made in de- signing the estimation technique match the deployment environment. Any unforeseen disturbances or hindrances in the environment deteriorate the BER performance of the system when the estimation system is not designed to combat the same. To combat such obstacles, estimation techniques must either be reinforced with modular systems which combat such observed types of disturbances, or be redesigned as a whole considering such observations of disturbances. In this paper a modular scheme to detect and combat sinusoidal variation in fading power is developed and tested by employing the developed scheme in a multiple-input-multiple-output (MIMO) wireless communication system which adopts Space-Time Block Coding (STBC) techniques.
113

Modeling of Multiple-Input Multiple-Output Radio Propagation Channels

Yu, Kai January 2002 (has links)
<p>In recent years, multiple-input multiple-output (MIMO)systems appear to be very promising since they can provide highdata rates in environments with sucient scattering byexploiting the spatial domain. To design a real MIMO wirelesssystem and predict its performance under certain circumstances,it is necessary to have accurate MIMO wireless channel modelsfor dierent scenarios. This thesis presents dierent models forindoor MIMO radio propagation channels based on 5.2 GHz indoorMIMO channel measurements.The recent research on MIMO radio channel modeling isbriey reviewed in this thesis. The models are categorized intonon-physical and physical models. The non-physical modelsprimarily rely on the statistical characteristics of MIMOchannels obtained from the measured data while the physicalmodels describe the MIMO channel (or its distribution) via somephysical parameters. The relationships between dierent modelsare also discussed.For the narrowband case, a non line-of-sight (NLOS)indoor MIMO channel model is presented. The model is based on aKronecker structure of the channel covariance matrix and thefact that the channel is complex Gaussian. It is extended tothe line-of-sight (LOS) scenario by estimating and modeling thedominant component separately.As for the wideband case, two NLOS MIMO channel modelsare proposed. The rst model uses the power delay prole and theKronecker structure of the second order moments of each channeltap to model the wideband MIMO channel while the second modelcombines a simple single-input single-output (SISO) model withthe same Kronecker structure of the second order moments.Monte-Carlo simulations are used to generate indoor MIMOchannel realizations according to the above models. The resultsare compared with the measured data and good agreement has beenobserved.</p>
114

Space-time Coded Modulation Design in Slow Fading

Elkhazin, Akrum 08 March 2010 (has links)
This dissertation examines multi-antenna transceiver design over flat-fading wireless channels. Bit Interleaved Coded Modulation (BICM) and MultiLevel Coded Modulation (MLCM) transmitter structures are considered, as well as the used of an optional spatial precoder under slow and quasi-static fading conditions. At the receiver, MultiStage Decoder (MSD) and Iterative Detection and Decoding (IDD) strategies are applied. Precoder, mapper and subcode designs are optimized for different receiver structures over the different antenna and fading scenarios. Under slow and quasi-static channel conditions, fade resistant multi-antenna transmission is achieved through a combination of linear spatial precoding and non-linear multi-dimensional mapping. A time-varying random unitary precoder is proposed, with significant performance gains over spatial interleaving. The fade resistant properties of multidimensional random mapping are also analyzed. For MLCM architectures, a group random labelling strategy is proposed for large antenna systems. The use of complexity constrained receivers in BICM and MLCM transmissions is explored. Two multi-antenna detectors are proposed based on a group detection strategy, whose complexity can be adjusted through the group size parameter. These detectors show performance gains over the the Minimum Mean Squared Error (MMSE)detector in spatially multiplexed systems having an excess number of transmitter antennas. A class of irregular convolutional codes is proposed for use in BICM transmissions. An irregular convolutional code is formed by encoding fractions of bits with different puncture patterns and mother codes of different memory. The code profile is designed with the aid of extrinsic information transfer charts, based on the channel and mapping function characteristics. In multi-antenna applications, these codes outperform convolutional turbo codes under independent and quasi-static fading conditions. For finite length transmissions, MLCM-MSD performance is affected by the mapping function. Labelling schemes such as set partitioning and multidimensional random labelling generate a large spread of subcode rates. A class of generalized Low Density Parity Check (LDPC) codes is proposed, to improve low-rate subcode performance. For MLCM-MSD transmissions, the proposed generalized LDPC codes outperform conventional LDPC code construction over a wide range of channels and design rates.
115

Distributed resource allocation for self-organizing small cell networks: a game theoretic approach

Semasinghe, Lakshika 09 September 2016 (has links)
Future wireless networks are expected to be highly heterogeneous and ultra dense with different types of small cells underlaid with traditional macro cells. In the presence of hundreds of different types of small cells, centralized control and manual intervention in network management will be inefficient and expensive. In this case, self-organization has been proposed as a key feature in future wireless networks. In a self-organizing network, the nodes are expected to take individual decisions on their behavior. Therefore, individual decision making in resource allocation (i.e., Distributed Resource Allocation) is of vital important. The objective of this thesis is to develop a distributed resource allocation framework for self-organizing small cell networks. Game theory is a powerful mathematical tool which can model and analyze interactive decision making problems of the agents with conflicting interests. Therefore, it is a well-appropriate tool for modeling the distributed resource allocation problem of small cell networks. In this thesis, I consider three different scenarios of distributed resource allocation in self-organizing small cell networks i.e., i). Distributed downlink power and spectrum allocation to ensure fairness for a small cell network of base stations with bounded rationality, ii). Distributed downlink power control for an ultra dense small cell network of base stations with energy constraints, iii). Distributed joint uplink-downlink power control for a small cell network of possibly deceitful nodes with full-duplexing capabilities. Specifically, I utilize evolutionary games, mean field games, and repeated games to model and analyze the three aforementioned scenarios. I also use stochastic geometry, which is a very powerful mathematical tool that can model the characteristics of the networks with random topologies, to design the payoff functions for the formulated evolutionary game and the mean field game. / October 2016
116

Optical wireless communications for micro-machines

Yuan, Wei Wen January 2011 (has links)
The main objective of this thesis is to develop a communication system that can minimize the micro-machine size and power consumption and maximize the link range and the number of micro-machines that can communicate simultaneously with the base station. Several possible communication systems are compared, including RF communications and active and passive free space optical communications. A directed, half duplex LOS link using a Ferroelectric liquid crystal (FLC) or multiple quantum well (MQW) modulating retroreflector-base passive uplink is then examined in more detail. Two potential geometries are described. In a broad-beam system, light from a source is broadcast to all micro-machines within the field of view (FOV). However, simulations show that the performance is unacceptable for most applications. In a narrow-beam system, light is holographically steered to active micro-machines within the same FOV. Therefore, the link budget has been improved. For a BER not exceeding 10-9, the 850 nm LC narrowbeam system can support maximum range of 146 m at a data rate of 10kbits/s, and the 1525 nm MQW narrowbeam system can support a maximum range of 34 m at a data rate of 10Mbits/s, when the transmitted power in the diffracted beam of the positive first order is 0.5 mW. Experiments have been carried out to verify the model. These were initially carried out with MQW Modulating RetroReflector (MRR). Results were then be used to modify the characteristics of these components in the model. Available components and discrete electronics have been used to set up a simple retro-reflecting link. Experiments have been performed at a limited data rate of 1 kbits/s over a limited range of 1m due to creating a uniform interrogation beam spot, and the active area of the receiver of 1 mm diameter. An algorithm to find the MQW MRR within the FOV is designed and tested.
117

A comparative investigation on performance and which is the preferred methodology for spectrum management; geo-location spectrum database or spetrum sensing

Ezebuka, Chijioke Ifakandu January 2016 (has links)
A Research Report submitted to the Faculty of Engineering and the Built Environment, University of Witwatersrand, in the partial fulfilment of the requirements for the degree of Master of Science in Engineering Johannesburg, 2015. / Due to the enormous demand for multimedia services which relies hugely on the availability of spectrum, service providers and technologist are devising a means or method which is able to fully satisfy these growing demands. The availability of spectrum to meet these demands has been a lingering issue for the past couple of years. Many would have it tagged as spectrum scarcity but really the main problem is not how scarce the spectrum is but how efficiently allocated to use is the spectrum. Once such inefficiency is tackled effectively, then we are a step closer in meeting the enormous demands for uninterrupted services. However, to do so, there are techniques or methodologies being developed to aid in the efficient management of spectrum. In this research project, two methodologies were considered and the efficiency of these methodologies in the areas of spectrum management. The Geo-location Spectrum Database (GLSD) which is the most adopted technique and the Cognitive radio spectrum sensing technique are currently the available techniques in place. The TV whitespaces (TVWS) was explored using both techniques and certain comparison based on performances; implementation, practicability, cost and flexibility were used as an evaluation parameter in arriving at a conclusion. After accessing both methodologies, conclusions were deduced on the preferred methodology and how its use would efficiently solve the issues encountered in spectrum management
118

Performance Analysis of Spectrum Sensing Schemes Based on Fractional Lower Order Moments for Cognitive Radios in Alpha- Stable Noise Environments

Unknown Date (has links)
Natural and manmade noise signals tend to exhibit impulsive behaviors. Therefore modeling those signals as α-stable processes is better suited towards the development of a practical spectrum sensing scheme. However, the performances of detectors operating in an α-stable noise environment are difficult to evaluate. This is because an α-stable random variable can usually only be modeled by the characteristic function since closed-form expressions are usually not available except for the special values of the characteristic exponent that correspond to the Cauchy and Gaussian noise distributions. In this thesis, we derive a general closed-form expression for the probability density function (PDF) of symmetric alpha stable processes having rational characteristic exponent (0<α≤2). Consequently, we obtain analytical expressions for the PDF and corresponding complementary cumulative distribution function (CCDF) of the proposed fractional lower order moment (FLOM) detector. Utilizing false alarm and detection probabilities, the performance analysis of the proposed spectrum sensing scheme is conducted with the assumption that the cognitive radio (CR) users are operating in non-fading channels. We validate the analytical results with Monte Carlo simulations. The effect of the distribution parameters on the receiver operating characteristic (ROC) curves is verified. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection
119

Dynamic resource allocation using stochastic optimization in wireless communications. / CUHK electronic theses & dissertations collection

January 2012 (has links)
無處不在的無線業務以其不斷增長的需求促進了對稀缺無線資源的高效利用。多年來,優化技術被廣泛地運用在無線資源分配的方案設計上,從而達到改善系統性能之目的。在此領域的大部分工作中,用於定義優化問題的系統參數被假設為精確可知。然而,實際的系統參數往往是時變且隨機的。忽略系統參數的不確定性極易導致資源分配決策偏離最優狀態,或者甚至違反系統運行約束而使分配決策不可行。 / 本論文提出了一套用於無線通信的動態資源分配的隨機優化框架。具體而言,本文抓住了不確定系統參數的隨機本質,從而建立結合實際的問題模型,並且開發了高效的算法,以獲得最佳的分配決策。本文將提出的框架成功地應用於三個很有前景的無線通信系統中:自適應正交頻分多址接入(OFDMA)系統,多輸入多輸出(MIMO)天線系統,以及位置感知網絡。每一個應用系統中都存在與實踐相關的挑戰,而這些挑戰則源自於傳統基於靜態優化的設計在提供滿意的服務質量(QoS)中遇到的困難。結果表明,使用隨機優化的動態資源分配,可達到了更加穩健的QoS性能,並且顯著增強系統的實用性。 / 在自適應OFDMA系統中,本文提出了一套“慢適應“的最優子載波分配方案。該方案通過採用更新遠慢於無線信道波動的資源分配策略,從而使計算複雜度和控制信令大大降低。本文根據不同的應用背景,將慢適應子載波分配問題描述成為幾個不同的隨機規劃問題。其中,我們設計了一個高效的算法專門用以求解機會約束規劃類型的子載波分配問題。 / 在MIMO天線系統中,本文提出了一套天線和發射功率聯合分配的方案,使利用多天線支持單一移動終端上的多個無線電模塊同時運行成為可能。該方案最大化了長期系統吞吐量,同時以容許偶爾違反系統約束的方式滿足每個無線模塊的短期傳輸速率需求。結果表明,最優天線和發射功率分配顯著提高系統的吞吐量和滿足QoS的成功概率;而最優天線分配與最優功率分配相比,對提高系統吞吐量有更大的貢獻。 / 在位置感知網絡中,本文提出了一套魯棒功率分配方案,用以抵抗網絡參數的不確定性,這些參數包括用戶位置以及信道狀態。本文提出了一種新的魯棒優化方法,用以獲得最優功率分配,從而提高定位精度和網絡能效。結果表明,魯棒方案顯著優於非魯棒的功率分配和平均分配方案。 / 本論文著眼於縮短傳統基於靜態優化的設計與其現實針對性之間的差距。鑒於許多無線系統的參數在本質上都具有隨機性,本文所提出的採用隨機優化的資源分配方法,有望在未來無線通信中得到更多的應用。 / The growing demand of ubiquitous wireless services has prompted the efficient utilization of scarce radio resources. Over the years, optimization techniques have been widely employed to design optimal resource allocation schemes to achieve performance improvement. Most work in this area assumes that the system parameters defining the optimization problem are precisely known. In practical systems, however, these parameters are often time varying and random. Ignoring the parameter uncertainties would easily lead to suboptimality or even infeasible solutions that violate system operation constraints. / This thesis presents a stochastic optimization framework for the dynamic resource allocation in wireless communications. In particular, practice-relevant problem formulations are proposed to capture the stochastic nature of the uncertain system parameters, and efficient algorithms are developed to obtain the optimal allocation decisions. The proposed framework has been successfully applied in three promising wireless systems: adaptive orthogonal frequency division multiple access (OFDMA) systems, multiple-input and multiple-output (MIMO) antenna systems, and location-aware networks. Each application contains practice-relevant challenges, where the conventional designs using deterministic optimization fail to provide satisfactory quality of service (QoS). The results demonstrate that the dynamic resource allocation using stochastic optimization achieves more robust QoS performance and remarkably enhances the system practicality. / In adaptive OFDMA systems, a slow adaptation scheme is proposed for optimal subcarrier allocation. The proposed scheme updates the resource allocation decisions on a much slower timescale than that of channel fluctuation, which drastically reduces the computational complexity and control signaling overhead. The problems are formulated into several stochastic programs based on different application scenarios. An efficient algorithm is developed for solving the chance constrained subcarrier allocation problem. / In MIMO antenna systems, an antenna-and-power allocation scheme is proposed to enable the use of multiple antennas to support multiple radios co-operating on the same mobile device. The proposed scheme maximizes the long-term system throughput while satisfying the short-term data rate requirement of each radio transmission with occasional outage. The results show that both system throughput and success probability of QoS satisfaction are improved, and the optimal antenna allocation contributes to a larger portion of throughput increase comparing with the optimal power allocation. / In location-aware networks, robust power allocation schemes are proposed to combat the uncertainties in network parameters including user positions and channel conditions. A novel robust optimization method is developed to obtain the optimal power allocation, which improves both localization accuracy and network energy efficiency. The results show that the robust schemes remarkably outperform both non-robust power allocation and uniform allocation. / The goal of this thesis is to bridge the gap between the current designs under the deterministic optimization framework and their practical relevance. Given the fact that many wireless system parameters are stochastic in nature, the proposed resource allocation methods using stochastic optimization are expected to find further applications in wireless communications. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Li, Weiliang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 157-175). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / 摘要 / Abstract --- p.iii / Acknowledgement --- p.vi / Contents --- p.ix / List of Figures --- p.xiii / List of Tables --- p.xvii / List of Acronyms --- p.xviii / List of Notations --- p.xxi / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Resource Allocation in Wireless Communications --- p.2 / Chapter 1.2 --- Stochastic Optimization and Its Applications --- p.4 / Chapter 1.2.1 --- Robust Optimization --- p.5 / Chapter 1.2.2 --- Chance Constrained Optimization --- p.8 / Chapter 1.3 --- Motivation and Research Focus --- p.10 / Chapter 1.3.1 --- Motivation --- p.10 / Chapter 1.3.2 --- OFDM and OFDMA Systems --- p.14 / Chapter 1.3.3 --- MIMO Antenna Systems --- p.16 / Chapter 1.3.4 --- Location-Aware Networks --- p.18 / Chapter 1.4 --- Contributions --- p.20 / Chapter 1.5 --- Organization --- p.23 / Chapter 2 --- Slow Subcarrier Allocation in Adaptive OFDMA Systems --- p.25 / Chapter 2.1 --- System and Channel Model --- p.29 / Chapter 2.1.1 --- Channel Model --- p.29 / Chapter 2.1.2 --- Slow Adaptive OFDMA --- p.30 / Chapter 2.2 --- Slow Adaptive OFDMA with Average Rate Constraints for Elastic Traffics --- p.32 / Chapter 2.2.1 --- Problem Formulation --- p.33 / Chapter 2.2.2 --- Computation of Expected Average Data Rate --- p.34 / Chapter 2.2.3 --- Numerical Results --- p.37 / Chapter 2.3 --- Slow Adaptive OFDMA with Average Rate Constraints for Inelastic Traffics --- p.40 / Chapter 2.3.1 --- Problem Formulation --- p.40 / Chapter 2.3.2 --- Numerical Results --- p.43 / Chapter 2.4 --- Slow Adaptive OFDMA with Probabilistic Rate Constraints --- p.46 / Chapter 2.4.1 --- Problem Formulation --- p.47 / Chapter 2.4.2 --- Safe Tractable Constraints --- p.48 / Chapter 2.4.3 --- Algorithm Design --- p.51 / Chapter 2.4.4 --- Problem Size Reduction --- p.59 / Chapter 2.4.5 --- Numerical Results --- p.61 / Chapter 2.5 --- Summary --- p.70 / Chapter 3 --- Dynamic Antenna-and-Power Allocation in Composite Radio MIMO Networks --- p.72 / Chapter 3.1 --- System Model --- p.76 / Chapter 3.1.1 --- Composite Radio System --- p.76 / Chapter 3.1.2 --- Channel Model --- p.77 / Chapter 3.1.3 --- Dynamic Antenna-and-Power Allocation --- p.78 / Chapter 3.2 --- Problem Formulation --- p.80 / Chapter 3.2.1 --- MIMO Channel Capacity --- p.80 / Chapter 3.2.2 --- Chance Constrained Formulation --- p.81 / Chapter 3.2.3 --- Safe Tractable Formulation --- p.82 / Chapter 3.3 --- Search for Feasible Solutions --- p.85 / Chapter 3.3.1 --- Algorithm Design --- p.87 / Chapter 3.4 --- Approach to Optimal Solution --- p.89 / Chapter 3.4.1 --- Cutting-Plane-Based Algorithm --- p.91 / Chapter 3.4.2 --- Optimal Antenna-and-Power Allocation --- p.95 / Chapter 3.5 --- Simulation Results --- p.96 / Chapter 3.6 --- Summary --- p.106 / Chapter 4 --- Robust Power Allocation for Energy-Efficient Location-Aware Networks --- p.107 / Chapter 4.1 --- System Model --- p.110 / Chapter 4.1.1 --- Network Settings --- p.110 / Chapter 4.1.2 --- Position Error Bound --- p.111 / Chapter 4.1.3 --- Directional Decoupling of SPEB --- p.113 / Chapter 4.2 --- Optimal Power Allocation via Conic Programming --- p.115 / Chapter 4.2.1 --- Problem Formulation Based on SPEB --- p.115 / Chapter 4.2.2 --- Problem Formulation Based on mDPEB --- p.117 / Chapter 4.2.3 --- Formulations with QoS Guarantee --- p.120 / Chapter 4.3 --- Robust Power Allocation under Imperfect Network Topology Parameters --- p.122 / Chapter 4.3.1 --- Robust Counterpart of SPEB Minimization --- p.123 / Chapter 4.3.2 --- Robust Counterpart of mDPEB Minimization --- p.131 / Chapter 4.4 --- Efficient Robust Algorithm Using Distributed Computations --- p.132 / Chapter 4.4.1 --- Algorithm for SPEB Minimization --- p.132 / Chapter 4.4.2 --- Algorithm for mDPEB Minimization --- p.136 / Chapter 4.5 --- Simulation Results --- p.137 / Chapter 4.5.1 --- Power Allocation with Perfect Network Topology Parameters --- p.137 / Chapter 4.5.2 --- Robust Power Allocation with Imperfect Network Topology Parameters --- p.140 / Chapter 4.6 --- Summary --- p.144 / Chapter 5 --- Conclusions and Future Work --- p.145 / Chapter 5.1 --- Conclusions --- p.145 / Chapter 5.1.1 --- Slow Adaptive OFDMA Systems --- p.146 / Chapter 5.1.2 --- Composite Radio MIMO Networks --- p.147 / Chapter 5.1.3 --- Energy-Efficient Location-Aware Networks --- p.148 / Chapter 5.2 --- Future Work --- p.150 / Chapter A --- Bernstein Approximation Theorem --- p.153 / Chapter B --- Ergodic MIMO Capacity and Moment Generating Function --- p.155 / Bibliography --- p.157
120

Non-orthogonal multiple access for 5G : design and performance enhancement

Liu, Yuanwei January 2016 (has links)
Spectrum scarcity is one of the most important challenges in wireless communications networks due to the sky-rocketing growth of multimedia applications. As the latest member of the multiple access family, non-orthogonal multiple access (NOMA) has been recently proposed for 3GPP Long Term Evolution (LTE) and envisioned to be a key component of the 5th generation (5G) mobile networks for its potential ability on spectrum enhancement. The feature of NOMA is to serve multiple users at the same time/frequency/code, but with di erent power levels, which yields a signi cant spectral e ciency gain over conventional orthogonal multiple access (OMA). This thesis provides a systematic treatment of this newly emerging technology, from the basic principles of NOMA, to its combination with simultaneously information and wireless power transfer (SWIPT) technology, to apply in cognitive radio (CR) networks and Heterogeneous networks (HetNets), as well as enhancing the physical layer security and addressing the fairness issue. First, this thesis examines the application of SWIPT to NOMA networks with spatially randomly located users. A new cooperative SWIPT NOMA protocol is proposed, in which near NOMA users that are close to the source act as energy harvesting relays in the aid of far NOMA users. Three user selection schemes are proposed to investigate the e ect of locations on the performance. Besides the closed-form expressions in terms of outage probability and throughput, the diversity gain of the considered networks is determined. Second, when considering NOMA in CR networks, stochastic geometry tools are used to evaluate the outage performance of the considered network. New closed-form expressions are derived for the outage probability. Diversity order of NOMA users has been analyzed based on the derived outage probability, which reveals important design insights regarding the interplay between two power constraints scenarios. Third, a new promising transmission framework is proposed, in which massive multipleinput multiple-output (MIMO) is employed in macro cells and NOMA is adopted in small cells. For maximizing the biased average received power at mobile users, a massive MIMO and NOMA based user association scheme is developed. Analytical expressions for the spectrum e ciency of each tier are derived using stochastic geometry. It is con rmed that NOMA is capable of enhancing the spectrum e ciency of the network compared to the OMA based HetNets. Fourth, this thesis investigates the physical layer security of NOMA in large-scale networks with invoking stochastic geometry. Both single-antenna and multiple-antenna aided transmission scenarios are considered, where the base station (BS) communicates with randomly distributed NOMA users. In addition to the derived exact analytical expressions for each scenario, some important insights such as secrecy diversity order and large antenna array property are obtained by carrying the asymptotic analysis. Fifth and last, the fundamental issues of fairness surrounding the joint power allocation and dynamic user clustering are addressed in MIMO-NOMA systems in this thesis. A two-step optimization approach is proposed to solve the formulated problem. Three e cient suboptimal algorithms are proposed to reduce the computational complexity. To further improve the performance of the worst user in each cluster, power allocation coe cients are optimized by using bi-section search. Important insights are concluded from the generated simulate results.

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