"In the design of any antenna radiator, single or multi-element, a significant amount of time and resources is spent on impedance matching. There are broadly two approaches to impedance matching; the first is the distributed impedance matching approach which leads to modifying the antenna geometry itself by identifying appropriate degrees of freedom within the structure. The second option is the lumped element approach to impedance matching. In this approach instead of modifying the antenna geometry a passive network attempts to equalize the impedance mismatch between the source and the antenna load. This thesis introduces a new technique of impedance matching using lumped circuits (passive, lossless) for electrically small (short) non-resonant dipole/monopole antennas. A closed form upper-bound on the achievable transducer gain (and therefore the reflection coefficient) is derived starting with the Bode-Fano criterion. A 5 element equalizer is proposed which can equalize all dipole/monopole like antennas. Simulation and experimental results confirm our hypothesis. The second contribution of this thesis is in the design of broadband, small size, modular arrays (2, 4, 8 or 16 elements) using the distributed approach to impedance matching. The design of arrays comprising a small number of elements cannot follow the infinite array design paradigm. Instead, the central idea is to find a single optimized radiator (unit cell) which if used to build the 2x1, 4x1, 2x2 arrays, etc. (up to a 4x4 array) will provide at least the 2:1 bandwidth with a VSWR of 2:1 and stable directive gain (not greater than 3 dB variation) in each configuration. Simulation and experimental results for a solution to the 2x1, 4x1 and 2x2 array configurations is presented. "

Finally, we extend the threshold optimization algorithm to solve a more general N-state distributed estimation problem. We combine multiple observations of a signal process via the maximum function for decision-making and find out that the optimal decision function can be implemented by means of thresholds under suitable technical conditions. We propose here a training sequence based algorithm for threshold adjustment. The algorithm is a variation of the Kiefer-Wolfowitz algorithm with expending truncations and randomized differences. Convergence of this algorithm is also established. / Prior to timing jitter robust receiver design, a measurement campaign was carried out on indoor UWB signal propagation in order to characterize the UWB indoor channel and provide a simulation platform. Channel parameters are analyzed based on measurement data, including path loss, RMS delay spread, amplitude distribution and correlation properties. / Ultra-wideband (UWB) technique has been the subject of extensive research in recent years due to its unique capabilities and potential applications, particularly in short-range multiple access wireless communications. Despite of many advantages over traditional narrow band systems, UWB impulse radio is sensitive to timing jitter effect. In this thesis, we devote to design a high speed UWB receiver which is robust under timing jitter. The basic idea is that the received signal is over-sampled within the sampling window and its maximum value or maximum absolute value is selected as the decision variable and to be compared with a threshold. A main advantage of this scheme is that its performance will not degrade if the timing jitter is shorter than half of the window length. Therefore, the proposed scheme is robust against timing jitter and no precise synchronization between the transmitter and receiver is required. However, how to determine the optimal threshold value is a critical issue for this new scheme. In this thesis, we propose a simple stochastic approximation (SA) approach to adjust the threshold recursively. The approach is based on a version of SA known as the Kiefer-Wolfowitz (KW) algorithm with expanding truncations and randomized differences. Corresponding to two different decision-making structures, two SA algorithms are presented and their convergence properties are analyzed, respectively. The proposed algorithms are effective in threshold optimization and the convergence rate is fast, as demonstrated by the numerical results. / Li Qiang. / "June 2005." / Adviser: Wing Shing Wong. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0440. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (p. 133-138). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

by Kin-Yu Cheung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 64-[68]). / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Multistage Interconnection Architectures --- p.2 / Chapter 1.2 --- Interconnection Topologies --- p.4 / Chapter 1.3 --- Design of Switch Module-An Example of Multichannel Switch --- p.7 / Chapter 1.4 --- Organization --- p.8 / Chapter 1.5 --- Publication --- p.9 / Chapter 2 --- BMSN and SpiderNet: Two Large Scale ATM Switches --- p.13 / Chapter 2.1 --- Introduction --- p.13 / Chapter 2.2 --- Architecture --- p.14 / Chapter 2.2.1 --- Topology --- p.14 / Chapter 2.2.2 --- Switch Modules --- p.15 / Chapter 2.3 --- Routing --- p.17 / Chapter 2.3.1 --- VP/VC Routing --- p.18 / Chapter 2.3.2 --- VP/VC Routing Control --- p.22 / Chapter 2.3.3 --- Cell Routing --- p.23 / Chapter 2.3.4 --- Alternate Path Routing for Fault Tolerance --- p.24 / Chapter 2.4 --- SpiderNet --- p.25 / Chapter 2.5 --- Performance and Discussion --- p.26 / Chapter 2.5.1 --- BMSN vs SpiderNet --- p.26 / Chapter 2.5.2 --- Network Capacity --- p.29 / Chapter 2.6 --- Concluding Remarks --- p.30 / Chapter 3 --- Multichannel ATM Switching --- p.39 / Chapter 3.1 --- Introduction --- p.39 / Chapter 3.2 --- Switch Design --- p.40 / Chapter 3.3 --- Channel Allocation Algorithms --- p.41 / Chapter 3.3.1 --- VC-Based String Round Robin (VCB-SRR) Algorithm --- p.41 / Chapter 3.3.2 --- Implementation of the VCB-SRR Algorithm --- p.43 / Chapter 3.3.3 --- Channel Group Based Round Robin (CGB-RR) Algorithm --- p.50 / Chapter 3.3.4 --- Implementation of the CGB-RR Algorithm --- p.51 / Chapter 3.4 --- Performance and Discussion --- p.53 / Chapter 3.5 --- Concluding Remarks --- p.57 / Chapter 4 --- Conclusion --- p.62 / Bibliography --- p.64

by Wai-Hung Kwok. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Preliminaries - Routing in Classical Circuit Switching Clos Net- work --- p.9 / Chapter 2.1 --- Formulation of route assignment as bipartite multigraph coloring problem --- p.10 / Chapter 2.1.1 --- Definitions --- p.10 / Chapter 2.1.2 --- Problem formulation --- p.11 / Chapter 2.2 --- Edge-coloring of bipartite graph --- p.12 / Chapter 2.3 --- Routing algorithm - Paull's matrix --- p.15 / Chapter 3 --- Principle of Routing Algorithm --- p.18 / Chapter 3.1 --- Definitions --- p.18 / Chapter 3.1.1 --- Bandwidth quantization --- p.18 / Chapter 3.1.2 --- Connection splitting --- p.20 / Chapter 3.2 --- Non-blocking conditions --- p.20 / Chapter 3.2.1 --- Rearrangeably non-blocking condition --- p.21 / Chapter 3.2.2 --- Strictly non-blocking condition --- p.22 / Chapter 3.3 --- Formulation of route assignment as weighted bipartite multigraph coloring problem --- p.23 / Chapter 3.4 --- Edge-coloring of weighted bipartite multigraph with edge splitting --- p.25 / Chapter 3.4.1 --- Procedures --- p.25 / Chapter 3.4.2 --- Example --- p.27 / Chapter 3.4.3 --- Validity of the color rearrangement procedure --- p.29 / Chapter 4 --- Routing Algorithm --- p.32 / Chapter 4.1 --- Capacity allocation matrix --- p.32 / Chapter 4.2 --- Connection setup --- p.34 / Chapter 4.2.1 --- Non-splitting stage --- p.35 / Chapter 4.2.2 --- Splitting stage --- p.36 / Chapter 4.2.3 --- Recursive rearrangement stage --- p.37 / Chapter 4.3 --- Connection release --- p.40 / Chapter 4.4 --- Realization of route assignment in packet level --- p.42 / Chapter 5 --- Performance Studies --- p.45 / Chapter 5.1 --- External blocking probability --- p.45 / Chapter 5.1.1 --- Reduced load approximation --- p.46 / Chapter 5.1.2 --- Comparison of external blocking probabilities --- p.48 / Chapter 5.2 --- Connection splitting probability --- p.50 / Chapter 5.3 --- Recursive rearrangement probability --- p.50 / Chapter 6 --- Conclusions --- p.52

R.M. Fano. / "January 2, 1948." / Bibliography: p. 34. / Army Signal Corps Contract W-36-039 sc-32037.

Thesis (M.S.)--Brigham Young University. Dept. of Electrical and Computer Engineering, 2006. / Includes bibliographical references (p. 53-54).

A significant challenge for fourth generation cellular systems is the reliable delivery of high speed (up to 1 gigabit per second) data to mobile or nomadic users throughout a cluttered urban environment. The wireless channel is a difficult channel over which to achieve high rate reliable communications. The wireless channel suffers many impairments such as small-scale multipath fading, shadowing, high path loss, co-channel interference, and Doppler shift due to mobility of the terminals and mobility in the propagation environment. Since radio spectrum is a scarce resource it is necessary to build cellular networks with high spectral efficiency. Two promising methods to solve this problem are multihop (MH) relaying and multiple-input multiple-output (MIMO) antenna techniques. The most difficult mobile users to serve reliably are those close to cell edges and those shadowed by large objects such as buildings. With MH relaying, a number of simple and inexpensive wireless relays are deployed throughout the cell to relay transmissions around obstacles and to reduce the path loss to distant mobile users. Also, MH relaying enables the deployment of small subcells throughout the cell, increasing the system's area averaged spectral efficiency. Various MIMO techniques can be used in scattering channels to increase capacity and reliability of data links in a wireless network. MH relaying and MIMO are key inclusions in emerging cellular standards such as IEEE 802.16 and LTE-Advanced, so it is necessary to study how these may be used jointly in a cellular environment. We look at various techniques available in MH relaying and MIMO, and assess the benefits and difficulties of these techniques when used in cellular systems. We put together a realistic cellular system model, with typical cellular topologies and well-accepted propagation models, and assess the performance of a multihop MIMO system. We find that there are tradeoffs in using these techniques jointly since they provide gains by somewhat conflicting methods. MH relaying lowers path loss and mitigates scattering in the channel, while MIMO benefits from significant scattering. As a result, it is necessary to understand how to design a MH-MIMO network carefully in order to maximize the net benefit. / Communications

Energy economy in mobile devices is becoming an increasinglyimportant factor as the devices become more advancedand rich in features. A large part of the energy footprint of amobile device comes from the wireless communication module,and even more so as the amount of trac increases.In this paper we study the energy footprint of a mobilebroadband hardware module, and how it is aected by software,by performing systematic power consumption measurements.We show that there are several cases where thesoftware does not properly take into account the eect thatdata communication has on the power consumption. Thisopens up for potential energy savings by creating better applicationsthat are aware of the energy characteristics of thecommunication layer.

<p>Communication tools such as text-based instant messaging, voice and video relay services, real-time video chat and mobile SMS and MMS have successfully been used among Deaf people.&nbsp / Several years of field research with a local Deaf community revealed that disadvantaged South African Deaf people preferred to communicate with both Deaf and hearing peers in South African&nbsp / Sign Language as opposed to text. Synchronous video chat and video relay services provided such opportunities. Both types of services are commonly available in developed regions, but not in&nbsp / developing countries like South Africa. This thesis reports on a workaround approach to design and develop an asynchronous video communication tool that adapted synchronous video codecs&nbsp / to store-and-forward video delivery. This novel asynchronous video tool provided high quality South African Sign Language video chat at the expense of some additional latency. Synchronous video&nbsp / codec adaptation consisted of comparing codecs, and choosing one to optimise in order to minimise latency and preserve video quality. Traditional quality of service metrics only addressed real-time video quality and related services. There was no such standard for asynchronous video communication. Therefore, we also enhanced traditional objective video quality&nbsp / metrics with subjective assessment metrics conducted with the local Deaf community.&nbsp / </p>

This thesis starts with a discussion of different classes of operation of power amplifiers (PAs). Comparing advantages and disadvantages of these classes, class AB is chosen as the best initial candidate for the design of broadband PA. Different methods for design of matching networks are first discussed. Some of them fall into the group of narrowband matching networks, while others are suitable for a broadband context. Broadband design methodologies are categorized into two groups of real-to-real transformations and complex-to-real transformations. Complex-to-real transformations are the most useful methods for this project, since design of power amplifiers deals with complex loads rather than just real loads. The design of broadband matching networks exploiting filter theory is presented in this thesis for synthesizing broadband and highly efficient power amplifiers (PAs). Starting with sets of optimum impedances over the targeted frequency band, the matching networks are designed using a systematic approach. The effects of load termination at the 2nd and 3rd harmonic on the PA performance (efficiency) are studied. The significance of proper termination, especially at the 2nd harmonic, is highlighted. To prevent further complication of the design process, though, specific harmonic termination (stubs) is avoided and special arrangement of the matching network (position of the bias network) is preferred, as it is found to lead to acceptable efficiency. Two PA prototypes were designed with the proposed methodology using 25W GaN devices. The designs targeted two frequency bands: 1.8 to 2.2 GHz (20% BW) and 1.8 to 2.7 GHz (40% BW). For the former, drain efficiency (DE) of 70% (+/–5%) and output power of 45.5 dBm (+/- 1.0dB) was measured while the latter achieved very promising efficiency of about 60% over the entire bandwidth.