This thesis presents RF front-end system design for both WLAN (Wireless Local Area Network) and SDARS (Satellite Digital Audio Radio System) applications using adaptive smart antenna technique. It is important to understand that smart antenna system with adaptive beam-forming provides the following advantages: 1. It can concentrate radio transmission on specific directions by modifying transmit/receive phase and amplitude characteristics, and therefore provides greater coverage and increased capacity. 2. It can greatly reduce multi-path fading effect and co-channel interference. This thesis first presents a complete 4-element smart antenna system for IEEE 802.11b/g WLAN applications. The prototype presented can interconnect with an of-the-shelf WLAN network card. The system is controlled via a microcontroller that adjusts the array pattern to capture the best signal. Measurements show that the system can increase the RSSI (Received Signal Strength Indicator) level significantly and therefore the SNR (Signal to Noise Ratio). This prototype is the first step towards a novel DBF (Digital Beam-Forming) smart antenna architecture. The second part of the thesis presents a 2-element smart antenna system for SDARS application. This prototype can be connected with an of-the-shelf SDARS digital receiver. The system was tested in a chamber and measurements show a controlled beam and increased gain. Ansoft HFSS was used to simulate the 2-element smart antenna and validate the testing results.

WiMAX is one of the most important broadband wireless technologies and is anticipated to be a viable alternative to traditional wired broadband techniques due to its cost efficiency. Being an emerging technology, WiMAX supports multimedia applications such as voice over IP (VoIP), voice conference and online gaming. It is necessary to provide Quality of Service (QoS) guaranteed with different characteristics, quite challenging, however, for Broadband Wireless Access (BWA) networks. Therefore, an effective scheduling is critical for the WiMAX system. Many traffic scheduling algorithms are available for wireless networks, e.g. Round Robin, Proportional Fairness (PF) scheme and Integrated Cross-layer scheme (ICL). Among these conventional schemes, some cannot differentiate services, while some can fulfill the service differentiation with a high-complexity implementation. This thesis proposes a novel scheduling algorithm for Orthogonal Frequency Division Multiplex/Time Division Multiple Access (OFDM/TDMA)-based systems, which extends the PF scheme to multiple service types with diverse QoS requirements. The design objective is to provide differentiated services according to their QoS requirements, while the objective can be achieved by adjusting only one unique parameter, the time window for evaluating the average throughput. By extensive simulation, it is shown that the proposed scheduling algorithm exploits the advantage of the PF scheme, enhancing the throughput, and distinguishes the services in terms of the average delay. Afterward, we prove the superiority of the new scheme over the conventional ones by showing simulation results.

Microwave filters possessing various forms are essential components in radar, satellite, and mobile communication systems. Increased demands for low-loss, miniature filters that can be mass produced at low cost have provided a significant challenge reinforcing the need for improving or even replacing the conventional microwave filters. In recent years, the concept of Photonic/Electromagnetic Bandgap (PBG/EBG) structures has attracted the attention of the microwave engineering community. The main feature of PBG/EBG structures is the existence of a bandgap in the frequency spectrum of a propagating photonic/electromagnetic wave. The motivation for adopting EBG structures stems from their capability to eliminate unwanted wave propagations in various microwave devices. This thesis investigates and proposes novel planar microstrip filters employing EBG structures in the form of slots etched on the ground plane. Such filters are not only compact, but also can improve the RF performance in both the passband and the stopband. This proposed concept is further extended to implement low-loss tunable lowpass filters, both digital and analogue, by integrating tuning elements directly into the slots. Transmission line circuit models are developed to design the proposed microstrip filters and tunable lowpass filters. To verify the concept and the validity of the developed circuit models, theoretical and experimental results are presented and carefully compared. Currently, dielectric resonator (DR) filters have been widely employed in wireless and satellite communication systems. Over the past two decades, tremendous progress has been made to reduce the size, and enhance the in-band and out-of-band performance of DR filters. However, the current approaches for implementing DR filters are relatively expensive and hardly amenable to mass production. Cost reduction remains a key limiting factor that needs to be addressed now. A new configuration of DR filters is presented in this thesis. The novel concept simplifies the assembly, integration, and alignment of DR filters, significantly reducing production time and costs. Not only is the design of the proposed multi-pole DR filters and diplexers examined, but also the fabrication technique. The experimental measurement results confirm the validity of the theoretical designs of the new filters, which makes this concept very attractive for further applications in both wireless and satellite communication.

The revolutionary concept of space-time coding introduced in the last decade has demonstrated that the deployment of multiple antennas at the transmitter allows for simultaneous increase in throughput and reliability because of the additional degrees of freedom offered by the spatial dimension of the wireless channel. However, the use of antenna arrays is not practical for deployment in some practical scenarios, e. g. , sensor networks, due to space and power limitations. <br /><br /> A new form of realizing transmit diversity has been recently introduced under the name of user cooperation or cooperative diversity. The basic idea behind cooperative diversity rests on the observation that in a wireless environment, the signal transmitted by the source node is overheard by other nodes, which can be defined as "partners" or "relays". The source and its partners can jointly process and transmit their information, creating a "virtual antenna array" and therefore emulating transmit diversity. <br /><br /> Most of the ongoing research efforts in cooperative diversity assume frequency flat channels with perfect channel knowledge. However, in practical scenarios, e. g. broadband wireless networks, these assumptions do not apply. Frequency-selective fading and imperfect channel knowledge should be considered as a more realistic channel model. The development of equalization and channel estimation algorithms play a crucial element in the design of digital receivers as their accuracy determine the overall performance. <br /><br /> This dissertation creates a framework for designing and analyzing various time and frequency domain equalization schemes, i. e. distributed time reversal (D-TR) STBC, distributed single carrier frequency domain (D-SC-FDE) STBC, and distributed orthogonal frequency division multiplexing (D-OFDM) STBC schemes, for broadband cooperative communication systems. Exploiting the orthogonally embedded in D-STBCs, we were able to maintain low-decoding complexity for all underlying schemes, thus, making them excellent candidates for practical scenarios, such as multi-media broadband communication systems. <br /><br /> Furthermore, we propose and analyze various non-coherent and channel estimation algorithms to improve the quality and reliability of wireless communication networks. Specifically, we derive a non-coherent decoding rule which can be implemented in practice by a Viterbi-type algorithm. We demonstrate through the derivation of a pairwise error probability expression that the proposed non-coherent detector guarantees full diversity. Although this decoding rule has been derived assuming quasi-static channels, its inherent channel tracking capability allows its deployment over time-varying channels with a promising performance as a sub-optimal solution. As a possible alternative to non-coherent detection, we also investigate the performance of mismatched-coherent receiver, i. e. , coherent detection with imperfect channel estimation. Our performance analysis demonstrates that the mismatched-coherent receiver is able to collect the full diversity as its non-coherent competitor over quasi-static channels. <br /><br /> Finally, we investigate and analyze the effect of multiple antennas deployment at the cooperating terminals assuming different relaying techniques. We derive pairwise error probability expressions quantifying analytically the impact of multiple antenna deployment at the source, relay and/or destination terminals on the diversity order for each of the relaying methods under consideration.

While the RF building blocks of narrowband system-on-chip designs have increasingly been created in CMOS during the past decade, researchers have started to look at the possibility of implementation of broadband transceivers in CMOS technology. High speed optical links with operating frequencies of up to 40 GHz and ultra wideband (UWB) wireless systems operating in 3 to 10 GHz frequency band are examples of these broadband applications. CMOS offers a low fabrication cost, and a higher level of integration compared with compound semiconductor technologies that currently claim broadband RFIC applications. <br /><br /> In this work, we focus on the design of broadband low-noise amplifiers: the fundamental building blocks of high data rate wireline and wireless telecommunication systems. A well established microwave engineering technique -distributed amplification- with a potential bandwidth up to the cut-off frequency of transistors is employed. However, the implementation of distributed amplifiers in CMOS imposes new challenges, such as gain attenuation because of substrate loss of on-chip inductors, a typical large die area, and a large noise-figure. These problems have been addressed in this dissertation as described below. <br /><br /> On-chip inductors, the essential components of the distributed amplifiers' gate and drain transmission lines, dissipate more and more power in silicon substrates as well as in metal lines as frequency increases, which in turn reduces the gain and deteriorates the input/output matching. Using active negative resistors implemented by a capacitively source degenerated configuration, we have fully compensated the loss of the transmission lines in order to achieve a flat gain of 10 dB over the entire DC-to-44 GHz bandwidth. <br /><br /> We have addressed another drawback of distributed amplifiers, large die area, by utilizing closely-placed RF transmission lines instead of spiral inductors. Because of a more compact implementation of transmission lines, the area of the distributed amplifiers is considerably reduced at the expense of extra design steps required for the modeling of the closely-placed RF transmission lines. A post-layout simulation method is developed to take into account the effect of inductive and capacitive coupling by incorporating a 3D EM simulator into the design process. A 9-dB 27-GHz distributed amplifier has been fabricated in an area as small as 0. 17 <em>mm</em>² using 180nm TSMC's CMOS process. <br /><br /> For wireless applications (UWB), a very low-noise figure is required for the broadband preamplifier. Conventional distributed amplifiers fail to provide a low noise figure mainly because of the noise injected by the terminating resistor of the gate transmission lines. We have replaced the terminating resistor with a frequency-dependent resistor which trades off the low frequency input matching of the distributed amplifier (not required for UWB) with a better noise performance. Our proposed design provides a gain of 12 dB with an average noise figure of 3. 4 dB over the entire 3-10 GHz band, advancing the state-of-the-art implementation of broadband LNAs.

With the recent advances in the development of wireless communication networks, Wireless Mesh Networks (WMNs) have been receiving considerable research interests in recent years. Many challenges need to be addressed for successful WMN deployment. One of the fundamental challenges is the need to support integrated services and provision different Quality of Service (QoS) for various applications. In order to allow differentiated services, Medium Access Control (MAC) has to provide priority management techniques at the link layer. In Code Division Multiple Access (CDMA) based WMNs, the interference phenomenon and the simultaneous transmissions must be considered. We propose two priority schemes for a distributed CDMA-based MAC WMNs. We take into account interference, multiple services, QoS requirements for each type of traffic, and the simultaneous transmission in CDMA. The first priority scheme is within a node. Each node has independent queues for each traffic class. According to QoS requirements, the queue that should be served first is determined. The second priority scheme is among neighbour nodes. It is proposed for possible multiple simultaneous transmissions with CDMA. This scheme gives a higher chance of correct transmission to high priority traffic than low priority traffic. In addition, we propose to use an adaptive spreading gain and a frame structure to achieve high resource utilization. Simulation results demonstrate that the proposed schemes can achieve effective QoS guarantee.

The problem of rank deficient multiple input multiple out (MIMO) systems arises when the number of transmit antennas M is greater than number of receive antennas N or when the channel gains are strongly correlated. Most of the optimal algorithms that deal with uncoded rank-deficient (under-determined) V-BLAST MIMO systems (e.g. Damen ,Meraim and Belfiore) suffer from high complexity and large processing time. Recently, some new optimal algorithms were introduced with low complexity for small constellations like 4-QAM yet they still suffer from very high complexity and processing time with large constellations like the 16 QAM. In order to reduce the complexity and the processing time of the decoding algorithms, some suboptimal algorithms were introduced. One of the most efficient suboptimal solutions for this problem is based on the Minimum mean square error decision-feedback equalizer (MMSE-DFE) followed by either sphere decoder or fano decoder. The performance of these algorithms is shown to be a fraction of dB from the maximum likelihood decoders while offering outstanding reduction in complexity compared to the most efficient ML algorithms (e.g. Cui and Tellambura algorithm). These suboptimal algorithms employ a two stage approach. In the first stage, the channel is pre-processed to transform the original decoding problem into a simpler form which facilitates the search decoding step. The second stage is basically the application of the sphere decoding search algorithm in the case of MMSE-DFE sphere decoding step or Fano decoder in the case of MMSE-DFE Fano decoder. In this study, various algorithms which deal with rank deficient MIMO systems such as Damen,Meraim and Belfiore algorithm ,Dayal and Varansi algorithm, and Cui and Tellambura algorithm are discussed and compared. Moreover, the MMSE-DFE sphere decoding algorithm and MMSE-DFE fano decoding algorithm are applied on uncoded V-BLAST rank deficient MIMO systems. The optimality of MMSE-DFE sphere decoding algorithm is analyzed in the case of V-BLAST 4-QAM. Furthermore, Simulation results show that when these algorithms are extended to cover large constellations, their performance falls within a fraction of dB behind the ML while achieving a significant decrease in the processing time by more than an order of magnitude when compared to the least

A gel electrophoresis technology based on absorption of ultraviolet radiation for fragment sizing of bio-molecular segments such as protein and nucleic acid is introduced for the first time. The new technology has the potential to improve conventional gel electrophoresis method by lowering the cost and increasing the throughpxcvfut. A cost effective, high sensitivity, short wavelength selective detector is an essential component to enable the proposed technology. In this thesis, hydrogenated amorphous silicon (a-Si:H) metal semiconductor metal(MSM) are investigated as the short wavelength detector of choice. The operation of planar MSM photoconductor-based photo detectors with very thin a-Si:H film thickness and aluminium electrodes is investigated. Experimental results of photocurrent measurements as well as responsivity and quantum efficiency are presented. The MSM photodetectors presented are fully compatible with state-of-the-art staggered gate thin film transistor (TFT) fabrication processes to enable large area pixel arrays for bio-molecular imaging.

An all-IP pervasive networking system provides a comprehensive IP solution where voice, data and streamed multimedia can be delivered to users at anytime and anywhere. Network selection is a key issue in this converged heterogeneous networking environment. A traditional way to select a target network is only based on the received signal strength (RSS); however, it is not comprehensive enough to meet the various demands of different multimedia applications and different users. Though some existing schemes have considered multiple criteria (e.g. QoS, security, connection cost, etc.) for access network selection, there are still several problems unsettled or not being solved perfectly. In this thesis, we propose a novel model to handle this network selection issue. Firstly, we take advantage of IEEE 802.21 to obtain the information of neighboring networks and then classify the information into two categories: 1) compensatory information and 2) non-compensatory information; secondly, we use the non-compensatory information to sort out the capable networks as candidates. If a neighboring network satisfies all the requirements of non-compensatory criteria, the checking of the compensatory information will then be triggered; thirdly, taking the values of compensatory information as input, we propose a hybrid ANP and RTOPSIS model to rank the candidate networks. ANP elicit weights to compensatory criteria and eliminates the interdependence impact on them, and RTOPSIS resolves the rank reversal problem which happens in some multiple criteria decision making (MCDM) algorithms such as AHP, TOPSIS, and ELECTRE. The evaluation study verifies the usability and validity of our proposed network selection method. Furthermore, a comparison study with a TOPSIS based algorithm shows the advantage and superiority of the proposed RTOPSIS based model.

In this thesis, I mainly focus on the evaluation of the upper bounds to the capacity of wireless networks. With the consideration of the two measures, the maximal transmission rate for any source-destination pair and the transport capacity of wireless networks, I summarize the most recent results to the upper bounds of these two measures first in this thesis. At the same time, I also improve and modify the previous results given in these papers. Moreover, I present a proof to the upper bound of maximal transmission rate with high probability by taking the fading of the channel into account when the full CSI is only known to the receivers. With a simple extension of the result, I derive an upper bound to the transport capacity of wireless networks without full CSI at the receiver side. A linear scaling of the upper bound to transport capacity is also derived when the path loss exponent is greater than three. Compared with the previous results, it is shown that the upper bound given in this thesis is much better for relatively large alpha and a minimum distance constraint.