Ng, Yuen Sum. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references. / Abstract also in Chinese. / Chapter 1. --- INTRODUCTION --- p.11 / Chapter 1.1 --- Motivation --- p.11 / Chapter 1.2 --- Specifications --- p.12 / Chapter 1.3 --- Organization of the Thesis --- p.16 / Chapter 1.4 --- References --- p.16 / Chapter 2. --- BASIC THEORY OF POWER AMPLIFIER AND TRANSMITTER FRONT-END --- p.18 / Chapter 2.1 --- Classification of Power Amplifier --- p.18 / Chapter 2.1.1 --- Class A --- p.20 / Chapter 2.1.2 --- Class B --- p.21 / Chapter 2.1.3 --- Class AB --- p.22 / Chapter 2.1.4 --- Class C --- p.23 / Chapter 2.1.5 --- Class D --- p.24 / Chapter 2.1.6 --- Class E --- p.25 / Chapter 2.1.7 --- Class F --- p.28 / Chapter 2.2 --- Figure-of-Mhrit of Power Amplifier --- p.28 / Chapter 2.2.1 --- Small Signal Analysis --- p.29 / Chapter 2.2.1.1 --- S-parameter --- p.29 / Chapter 2.2.1.2 --- Gain and Stability --- p.29 / Chapter 2.2.2 --- Large Signal Analysis --- p.32 / Chapter 2.2.2.1 --- 1-dB compression point --- p.33 / Chapter 2.2.2.2 --- Third-order intermodulation point --- p.33 / Chapter 2.2.2.3 --- Power Gain --- p.35 / Chapter 2.2.2.4 --- Drain Efficiency and Power Added Efficiency --- p.35 / Chapter 2.2.2.5 --- AM-AM and AM-PM conversion --- p.36 / Chapter 2.2.3 --- Modulation Analysis --- p.36 / Chapter 2.2.3.1 --- Constellation Diagram and Error Vector Magnitude --- p.36 / Chapter 2.3 --- Reference --- p.37 / Chapter 3. --- CIRCUIT DESIGN OF POWER AMPLIFIER --- p.39 / Chapter 3.1 --- Introduction --- p.39 / Chapter 3.2 --- Topology of the Power Amplifier Design --- p.39 / Chapter 3.3 --- Design in Power Amplifier --- p.40 / Chapter 3.2.1 --- Power Stage --- p.40 / Chapter 3.2.2 --- Driver Stage and Input matching --- p.46 / Chapter 3.4 --- Simulation Result on Power Amplifier --- p.49 / Chapter 3.5 --- Layout consideration --- p.50 / Chapter 3.6 --- Measurement Result on Power Amplifier --- p.51 / Chapter 3.4.1 --- Small signal measurement --- p.52 / Chapter 3.4.2 --- Large signal measurement --- p.55 / Chapter 3.4.3 --- Modulation measurement --- p.56 / Chapter 3.7 --- Performance Summary --- p.58 / Chapter 3.8 --- Reference --- p.59 / Chapter 4. --- CIRCUIT DESIGN OF TRANSMITTER FRONT-END --- p.60 / Chapter 4.1 --- Introduction --- p.60 / Chapter 4.2 --- Topology of the Transmitter Front-End Design --- p.61 / Chapter 4.3 --- Design in transmitter front-end circuit --- p.64 / Chapter 4.2.1 --- I/Q Modulator --- p.64 / Chapter 4.2.2 --- Power Amplifier --- p.66 / Chapter 4.2.3 --- On-chip LC Balun --- p.72 / Chapter 4.4 --- Simulation Result of the Transmitter Front-End Design --- p.74 / Chapter 4.5 --- Layout consideration --- p.75 / Chapter 4.6 --- Measurement Result of the Transmitter Front-End Design --- p.76 / Chapter 4.4.1. --- Transmitter Front-End Measurement --- p.77 / Chapter 4.4.1.1 --- Output Reflection coefficient --- p.77 / Chapter 4.4.1.2 --- Large Signal Measurement --- p.78 / Chapter 4.4.1.3 --- Modulation Measurement --- p.81 / Chapter 4.4.2. --- LC Balun Measurement --- p.84 / Chapter 4.7 --- Performance Summary of the transmitter front-end circuit --- p.86 / Chapter 4.8 --- Reference --- p.89 / Chapter 5. --- CONCLUSION --- p.90 / Chapter 6. --- FUTURE WORK --- p.91

Multiple-input multiple-output (MIMO) antennas can be exploited to provide high data rate using a limited bandwidth through multiplexing gain. MIMO combined with orthogonal frequency division multiplexing (OFDM) could potentially provide high data rate and high spectral efficiency in frequency-selective fading channels. MIMO-OFDM technology has been widely employed in modern communication systems, such as Wireless Local Area Network (WLAN), Long Term Evolution (LTE) and Worldwide Interoperability for Microwave Access (WiMAX). However, most of the conventional schemes either are computationally prohibitive or underutilize the full performance gain provided by the inherent merits of MIMO and OFDM techniques. In the first part of this dissertation, we firstly study the channel matrix inversion which is commonly required in various MIMO detection schemes. An algorithm that exploits second-order extrapolation in the time domain is proposed to efficiently reduce the computational complexity. This algorithm can be applied to both linear detection and non-linear detection such as ordered successive interference cancellation (OSIC) while maintaining the system performance. Secondly, we study the complexity reduction for Lattice Reduction Aided Detection (LRAD) of MIMO-OFDM systems. We propose an algorithm that exploits the inherent feature of unimodular transformation matrix that remains the same for relatively highly correlated frequency components. This algorithm effectively eliminates the redundant brute-force lattice reduction iterations among adjacent subcarriers. Thirdly, we analyze the impact of channel coherence bandwidth on two LRAD algorithms. Analytical and simulation results demonstrate that carefully setting the initial calculation interval according to the coherence bandwidth is essential for both algorithms. The second part of this dissertation focuses on efficient multi-user (MU) scheduling and coordination for the uplink of WLAN that uses MIMO-OFDM techniques. On one hand, conventional MU-MIMO medium access control (MAC) protocols require large overhead, which lowers the performance gain of concurrent transmissions rendered by the multi-packet reception (MPR) capability of MIMO systems. Therefore, an efficient MU-MIMO uplink MAC scheduling scheme is proposed for future WLAN. On the other hand, single-user (SU) MIMO achieves multiplexing gain in the physical (PHY) layer and MU-MIMO achieves multiplexing gain in the MAC layer. In addition, the average throughput of the system varies depending on the number of antennas and users, average payload sizes, and signal-to-noise-ratios (SNRs). A comparison on the performance between SU-MIMO and MU-MIMO schemes for WLAN uplink is hence conducted. Simulation results indicate that a dynamic switch between the SU-MIMO and MU-MIMO is of significance for higher network throughput of WLAN uplink. / Graduation date: 2013

L.B. Arguimbau ... [et al.]. / "September 20, 1954." / Bibliography: p. 49. / Army Signal Corps Contract DA36-039 sc-42607 Project 132B Dept. of the Army Project 3-99-12-022

This thesis studies cooperative techniques that rely on femtocell user diversity to improve the downlink communication quality of macrocell users. We analytically analyze and evaluate the achievable performance of these techniques in the downlink of Rayleigh fading channels. We provide an approximation of both the bit-error rate (BER) and the data throughput that macrocell users receive with femtocell user cooperation. Using simulations, we show that under reasonable SNR values, cooperative schemes enhance the performances of macrocells by improving the BER, outage probability, and data throughput of macrocell users significantly when compared with the traditional, non-cooperative schemes. / Graduation date: 2012

Not available

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

No description available.

Wireless communication is a rapidly growing field with many of its aspects undergoing constant enhancement. The use of cross-layer design (CLD) in current technologies has improved system performance in terms of Quality-of-Services (QoS) guarantees. While multimedia transmission is difficult to achieve, CLD is capable of incorporating techniques to achieve multimedia transmission without high complexity. Many systems have incorporated some form of adaptive transmission when using a cross-layer design approach. Various challenges must be overcome when transmitting multimedia traffic; the main challenge being that each traffic type, namely voice; image; and data, have their own transmission QoS; delay; Symbol Error Rate (SER); throughput; and jitter requirements. Recently cross-layer design has been proposed to exchange information between different layers to optimize the overall system performance. Current literature has shown that the application layer and physical layer can be used to adequately transmit multimedia over fading channels. Using Reed-Solomon coding at the application layer and Rate Adaption at the physical layer allows each media type to achieve its QoS requirement whilst being able to transmit the different media within a single packet. The following dissertation therefore strives to improve traffic through-put by introducing an unconventional rate adaption scheme and by using power adaption to achieve Symbol Error Rate (SER) QoS in multimedia transmission. Firstly, we introduce a system which modulates two separate sets of information with different modulation schemes. These two information sets are then concatenated and transmitted across the fading channel. The receiver uses a technique called Blind Detection to detect the modulation schemes used and then demodulates the information sets accordingly. The system uses an application layer that encodes each media type such that their QoS, in terms of SER, is achieved. Simulated results show an increase in spectral efficiency and the system achieves the required Symbol Error Rate constraint at lower Signal to Noise Ratio (SNR) values. The second approach involves adapting the input power to the system rather than adapting the modulation scheme. The two power adaptive schemes that are discussed are Water- Filling and Channel Inversion. Channel Inversion allows the SER requirement to be maintained for low SNR values, which is not possible with Rate Adaption. Furthermore, the system uses an application layer to encode each media type such that their QoS is achieved. Simulated results using this design show an improvement in through-put and the system achieves the SER constraint at lower SNR values. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2013.

Thesis (MScEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The high performance of present digital phase-locked loops makes it the preferred choice for the generation of stable, low noise, tunable local oscillators in wireless communications applications. Most transmitters use superheterodyn techniques for up-conversion of the modulated signal to the required transmission frequency. Another technique is to inject the modulation signal into a phase-locked loop and consequently generate a frequency modulated signal directly at the transmission frequency. The aim of this study is to obtain a synthesizer configuration for the effective generation of wideband FM, considering both passive and active loop filters. The selection is based on synthesizer output signal quality, settling time and loop response to the modulation signal. / AFRIKAANSE OPSOMMING: Die hoe werksverrigting van fase-sluit lusse maak dit die verkiesde keuse vir die generasie van stabiele, lae ruis, verstelbare ossillators vir draadlose kommunikasie toepassings. Meeste senders gebruik "superheterodyn" tegnieke vir die op-menging van die gemoduleerde sein na die verlangde uitsaai frekwensie. 'n Ander tegniek is om die modulasie sein in 'n fase-sluit Ius te voer en so doende 'n gemoduleerde sein direk by die transmissie frekwensie te genereer. Die doel van hierdie studie is om 'n sintetiseerder konfigurasie te verkry vir die effektiewe opwekking van 'n wyeband FM sein, deur beide passiewe en aktiewe Ius filters in konsiderasie te neem. Die seleksie geskiet gebaseer op sintetiseerder uittree sein kwaliteit, sluit tyd en Ius gedrag as gevolg van die modulasie sein.

Orientador: José Cândido Silveira Santos Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-22T14:30:38Z (GMT). No. of bitstreams: 1 Nunes_AdailtonAntonioGaliza_M.pdf: 941738 bytes, checksum: 0240eca4ba132d2f778db9941bcfaeee (MD5) Previous issue date: 2013 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The abstract is available with the full electronic document / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica