published_or_final_version / abstract / Electrical and Electronic Engineering / Master / Master of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

Architectures of matched filter in packet detector, CFO corrector, FFT output reorder buffer and phase tracking block are optimized for low complexity. Implemented in O.13-mum CMOS technology, the proposed baseband receiver system has the core area of 2.5 mm2 and the estimated power consumption is 170 mW, which is equivalent to the energy efficiency of 88 pJ/b at 480 Mbps data rate. The implementation results verify the robustness, low complexity and power efficiency of the proposed MB-OFDM UWB baseband receiver. / As an OFDM-based system, MB-OFDM UWB is vulnerable and sensitive to carrier frequency offset (CFO). We employ multipartite table method (MTM) to implement arctangent and sin/cos functions for frequency synchronization. Compared with traditional algorithms, MTM has the advantages of low cost, low power consumption and higher processing speed. Residual phase distortion is corrected by a highly simplified phase tracking method, which also has better performance compared with traditional phase tracking scheme. / Synchronization plays the key role for the performance of the whole baseband receiver system. In this dissertation, a dual-threshold (DT) packet detection scheme is proposed for timing synchronization. Compared with traditional cross-correlation algorithm, DT has much better detection performance, especially in high noise environment. / Ultra-wideband (UWB) technology, targeting at wireless personal area networks (WPANs),brings the convenience of high-speed and short-range wireless interconnects. As a novel communication technique, multi-band orthogonal frequency division multiplexing (MB-OFDM) UWB has the features of high spectrum efficiency, multiple access capability and robustness against narrow band interference. However, its inherent high complexity and the requirement of powerful processing for good performance are the obstacles for practical application. / Fan, Wen. / Adviser: Choy Chiu-Sing. / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 105-112). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Hu Fan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 77-81). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Evolution of Mobile Communications --- p.1 / Chapter 1.2 --- Overview of Multicarrier Systems --- p.3 / Chapter 1.3 --- Outline of This Thesis --- p.5 / Chapter 2 --- Multicarrier Communication Systems --- p.7 / Chapter 2.1 --- Introduction --- p.7 / Chapter 2.2 --- Multicarrier Modulation (MCM) Scheme versus Single Carrier Modulation (SCM) Scheme --- p.8 / Chapter 2.3 --- Orthogonal Frequency Division Multiplexing (OFDM) Systems --- p.12 / Chapter 2.4 --- Multicarrier CDMA --- p.16 / Chapter 2.4.1 --- MC-CDMA --- p.17 / Chapter 2.4.2 --- MC-DS-CDMA --- p.18 / Chapter 2.4.3 --- MT-CDMA --- p.19 / Chapter 3 --- Optimization for MC-CDMA Systems --- p.22 / Chapter 3.1 --- System Model --- p.22 / Chapter 3.2 --- Optimization with Normalized Power --- p.27 / Chapter 3.2.1 --- Transmission Time Minimization --- p.27 / Chapter 3.2.2 --- Throughput Maximization --- p.32 / Chapter 3.2.3 --- Performance --- p.33 / Chapter 3.3 --- Mathematical Programming --- p.36 / Chapter 3.3.1 --- Nonlinear Programming --- p.37 / Chapter 3.3.2 --- Convex Programming --- p.39 / Chapter 3.4 --- Optimization with Power Allocation --- p.42 / Chapter 3.4.1 --- Transmission Time Minimization with Power Allocation --- p.42 / Chapter 3.4.2 --- Throughput Maximization with Power Allocation --- p.43 / Chapter 3.4.3 --- Power Minimization --- p.44 / Chapter 3.5 --- Long-range Optimization --- p.45 / Chapter 3.5.1 --- Long-range Transmission Time Minimization --- p.46 / Chapter 3.5.2 --- Long-range Throughput Maximization --- p.50 / Chapter 3.5.3 --- Long-range Power Minimization --- p.51 / Chapter 3.5.4 --- Performance --- p.53 / Chapter 4 --- Joint Scheduling and Resource Allocation --- p.58 / Chapter 4.1 --- Queueing Model --- p.58 / Chapter 4.2 --- Problem Formulation --- p.62 / Chapter 4.3 --- Suboptimal Algorithm --- p.64 / Chapter 4.4 --- Performance --- p.69 / Chapter A --- Convexity Proof of Problem (3.32) --- p.73 / Chapter B --- Convexity Proof of Problem (3.36) --- p.75 / Bibliography --- p.77

No description available.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Leonard J. Cimini, Jr., Electrical and Computer Engineering. Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Recent years, Orthogonal Frequency Division Multiplexing (OFDM) system gets more and more attentions for its great benefit to the optical fiber communication system for improving the transmission performance. Not only better performance in long distance transmission but also high bit-rate is attractive feature of the OFDM system. The OFDM technology has been developed for the wireless communication system, and is now used in Asymmetric Digital Subscriber Line (ADSL), ETSI Digital Audio Broadcasting (DAB), Digital Video Broadcasting (DVB), High Definition Television (HDTV), Wireless Local Area Network (WLAN) and so on. The OFDM is extensively used in broadband wired and wireless communication systems, and it solves the problem of intersymbol interference (ISI) effectively. Actually, the OFDM is a kind of Multi-Carrier Modulation (MCM), and it is not a brand-new technology. The history of the OFDM can be traced back to 1966 when Chang of Bell Labs introduced the concept of the OFDM. In this thesis, I will briefly introduce the background of optical fiber communication system, then, explain my motivation and the structure of this thesis. Next, theoretical study has been conducted. For the simulation, I discuss the performance of the OFDM system related to the number of subcarriers and the erbium-doped fiber amplifier (EDFA) repeater output power. It revealed that small number of subcarriers had better transmission performance. In my study case, repeater output power of 0dBm was the optimum condition. In addition, experimental study has been conducted. For the experiment, the waveform required for the OFDM signal generation was calculated offline, and it was realized by the Arbitrary Waveform Generator (AWG). Finally, this thesis is concluded.

Long Term Evolution (LTE) developed by Third Generation Partnership Project (3GPP) is expected to be the standard of the Fourth-Generation (4G) of wireless communication system. LTE supports Frequency Division Duplex (FDD) and Time Division Duplex (TDD), and both of them are based on Orthogonal Frequency Division Multiplexing (OFDM) system in downlink. OFDM systems are sensitive to timing and frequency offset. Therefore, synchronization plays an important role in OFDM systems. In this thesis, we study synchronization problems of a LTE FDD baseband receiver. Particularly, we develop a complete procedure to deal with the synchronization problems. The basic design concept and procedure are as follows: The receiver estimates and compensates the timing and frequency offset by using the repetition property of the cyclic prefix. In the meanwhile, the receiver also detects cyclic prefix mode (or the length of the cyclic prefix). After the frequency offset has been compensated, the receiver then processes cell search. To this end, we multiply each subcarrier by the synchronization sequence provided by LTE specification and transform them into time domain. We then estimate the channel energy in time domain to detect the Cell Identity (Cell ID). Using computer simulations, we verify that the designed receiver performs well.

Orthogonal Frequency Division Multiple Access (OFDMA) uplink systems have been adopted generally in wireless communication in recent years. By combining Orthogonal Frequency Division Multiplexing (OFDM) with Frequency Division Multiple Access (FDMA), OFDMA systems divide all subcarriers in frequency domain into several mutually exclusive subbands, and assign the subbands to different user, transmitting different kinds of data by the orthogonality between subcarriers. The users¡¦ Carrier Frequency Offsets (CFO) caused by Doppler effects and/or misadjusted local oscillators may destroy the orthogonality between subcarriers, then lead to Multiple Access Interference (MAI) for all users, the MAI may degrade the performance of bit error rate. Several MAI suppression or cancellation schemes have been investigated to mitigate the effect of MAI, however, these schemes work on the hypothesis of known CFOs. As the result, it is the crucial issue for the multiuser CFOs estimation in OFDMA uplink systems. In this paper, we propose the Minimum Mean Square Error Criterion (MMSEC) estimation scheme to achieve multiuser CFOs estimation in Additive White Gaussian Noise (AWGN) environment. By modifying the MAI suppression weighting in [9], the MMSEC scheme search desired user¡¦s true CFO with CFO trial parameter, while the CFO trial parameter is equal to true CFO, the modified MAI suppression weighting will suppress the MAI ideally and then separate the desired user¡¦s estimated signal from received signal. Thus the distribution of estimated signal is highly concentrated in each of quadrant in the signal constellation, and it will have the minimum mean square error in each of quadrant. Compare with the MUtiple SIgnal Classification (MUSIC) scheme [12] and the Estimation of Signal Parameter via Rotational Invariance Technique (ESPRIT) scheme [13], they deal with the fully loaded problem by extending cyclic prefix, that may cause the redundant power consumption or degrade data throughput, the advantage of the MMSEC scheme is that it can works on fully load without extending cyclic prefix. Because despite fully loaded, the CFO trial parameter search desired user¡¦s true CFO in reasonable range until it causes minimum mean square error. The simulation result shows that the non-fully loaded system mean square error (MSE) performance is superior to the MUSIC and ESPRIT schees at high signal to noise ratio, while system is fully loaded, the system MSE performance is also acceptable.