The fourth generation cellular mobile communication system in the future needs to provide high data rate transmissions. Multi-Tone CDMA (MT-CDMA) system combines the advantages of CDMA and OFDM, and it is one of the promising choices for the fourth cellular mobile communication system. In order to raise the performance, we amend MT-CDMA named Modified MT-CDMA. We use different pilot arrangement in different channel to enhance the channel estimation of system. The receiver architecture includes a baseband signal detection and a channel estimation. We use a pilot symbol to estimation the channel. In this thesis, we make a study of pilot arrangement on different channel estimation performance of system. We use Least Square estimation(LS)¡Blinear interpolation¡Bspline interpolation¡BFFT/IFFT interpolation and spline interpolation combine FFT/IFFT algorithm to estimate the system performance.

Multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) technology has been used widely in many wireless communication systems. Signals will be distorted when they are transmitted in wireless channels. For the reason that wireless channel is time or location variant, we have to estimate the channel impulse response and use the channel state information to compensate the channel distortion. Pilot signals can be spaced separated in the transmitted symbols. In the receiver, the channel impulse response can be estimated at the positions of pilot signals. The other channel information at the data signals can be obtained by interpolating the estimated channel impulse response. However, error caused by channel interpolation can not be avoided. In this paper we propose a pilot-aided iterative maximum likelihood (ML) channel estimation algorithm for MIMO OFDM systems. At first, an ML channel estimate is obtained by using pilot tones. The receiver uses the estimated channel to help the detection/decision of data signals. And then the channel estimation treats the detected signals as known data to perform a next stage channel estimation iteratively. By utilizing the iterative channel estimation and signal detection process we can reduce the estimation error caused by channel interpolation between pilots. The accuracy of the channel estimation can be improved by increasing the number of iteration process. Simulation results demonstrate the iterative ML channel estimation algorithm can provide better mean-square-error and bit-error-rate performance than conventional methods. By changing the system parameters we can see that the improvement provided by this algorithm is different. Systems with fewer pilots have more improvement from the iterative ML algorithm. On the other hand, systems with more pilots have less improvement from the iterative algorithm. Finally, several channel environments are also considered in this thesis to compare the performance improvement introduced by the iterative algorithm.

Many satellite applications require a model that represents a surface as it deforms over time. Yet, space applications demand a precise, low-weight, low-volume, and easy to implement solution. A metrology sensing system is presented in this thesis, consisting of a series of cameras and laser dot projectors positioned along the length of the antenna. This system accurately models the geometry of the surface to meet the demands of a space based radar. Each laser dot projector casts a matrix of points onto the antenna surface. The points are then imaged simultaneously by a pair of cameras, each having a different, but overlapping, viewpoint. Given the two overlapping images, a Gaussian nonlinear least squares algorithm solves the stereo-triangulation problem which provides the coordinates of the projected points and thereby maps the surface. There are three different strategies discussed in this thesis. The first strategy assumes the positions and orientations of the cameras are absolutely known. This produces an extremely accurate result; yet it is unrealistic to assume absolute knowledge of cameras locations and orientations for the application. The next strategy assumes the positions and orientations of the cameras are completely unknown in addition to the unknown surface. This program produces a less accurate, but more realistic, result considering the dynamic nature of rigid structures in space. To increase the accuracy and improve the robustness of these results, the third method employs a global metrology sensing system to reduce the uncertainty in the location and orientation of the outboard cameras relative to the center camera. This approach estimates the surface extremely accurately and, although more complex, offers advantages and addresses the desire for a family of designs wherein higher accuracy is achievable by further optimization.

This thesis will investigate the impact of the use of the Phasor Measurement Units (PMU) on the state estimation problem. First, incorporation of the PMU measurements in a conventional state estimation program will be discussed. Then, the effect of adding PMU measurements on the state estimation solution accuracy will be studied. Bad data processing in the presence of PMU measurements will also be presented. Finally, a multiarea state estimation method will be developed. This method involves a two level estimation scheme, where the first level estimation is carried out by each area independently. The second level estimation is required in order to coordinate the solutions obtained by each area and also to detect and identify errors in the boundary measurements. The first objective of this thesis is to formulate the full weighted least square state estimation method using PMUs. The second objective is to derive the linear formulation of the state estimation problem when using only PMUs. The final objective is to formulate a two level multi-area state estimation scheme and illlustrate its performance via simulation examples.

This research analyzes and demonstrates the local position determination problem on Earth using a novel instrument, the Compass Star Tracker. Special focus is given to the theoretical development of the mathematics of local position determination, the design and fabrication of a proof-of-concept instrument, an error source analysis, and the experimental tests used to validate the position determination concepts. Star sensors are typically used as attitude determination instruments on spacecraft orbiting Earth. In this capacity, the star sensor determines the orientation of the spacecraft using digital images of the stars. This research utilizes the basic functionality of the star sensor in a new way; the orientation information from the star image is used to determine a user's latitude and longitude coordinates on Earth. This concept is valuable because it allows users to determine their position autonomously. The fundamental concepts that enable local position determination were originally published in Drs. Samaan, Mortari, and Junkins (AAS 04-007). This research improves upon that work by eliminating the zenith-orientation constraint and providing several crucial theoretical corrections. In addition to the position determination mathematics, this research provides analysis of the theoretical and practical error sources associated with the position determination problem. This research also details the design, fabrication, and experimental test program of a proof-of-concept Compass Star Tracker. Together, the theoretical development, error analysis, instrument design, and test program serve as validation of the the position determination concept. This work is intended as the first of many steps toward eventual deployment of autonomous position determination sensors on the Moon and Mars.

The direct sequence ultra-wideband (DS-UWB) system has the characteristics of low transmission power constraints and wide transmitted bandwidth. The wide bandwidth will introduce fine timing resolution and severe inter-symbol interference (ISI), which will is cause larger delay spread. Therefore, the traditional acquisition methods are no longer suitable here. A modified acquisition method and a coarse channel estimation algorithm are proposed in this thesis. Three different strategies with composition of acquisition and channel estimation are compared. Based on three strategies, the tasks of coarse acquisition and channel estimation can be achieved with limited length of acquisition sequence. From simulation results, the parallel strategy is robust enough to operate under the UWB channel in severe ISI conditions and the time duration for completing the tasks of coarse acquisition and channel estimation meets the specification of IEEE 802.15.3a.

With the rapid growth of multimedia information, video coding standards have become crucial when transmitting large amount of video data. Motion estimation promises to be the key to high performance in video coding by removing the temporal redundancy of video data for storage and transmission. Video transcoding also becomes a significant scheme applied in different bandwidth transform. Due to their fundamentality, research works on motion estimation and video transcoding have been conducted extensively. In this thesis, an overview of video compression technique is presented with emphasis on motion estimation. Then, a survey of most representative motion estimation search algorithms and the proposed motion estimation algorithms are introduced. The evaluation and analysis of these algorithms based on a number of experiments on several famous test video sequences is presented. In addition, an efficient video transcoding via visual attention model with Lagrange optimization to minimum rate-distortion cost is proposed. Finally, an investigation of the future trend of video coding is discussed. Through the proposed algorithms of motion estimation, the computational complexity can be significantly reduced despite the fact that the objective quality of motion compensated images is slightly degraded. Moreover, through the proposed video transcoding method, the bit rate can be reduced to fit the requirement of bandwidth.

Multimedia on network has been an integral part of our life because of the development of network and the evolution of video transmission technology. Motion estimation algorithm is an important part of video transmission technology. If we can parallelize the calculation, the efficiency of will be raised in order to be realized on embedded system. At present, the more common estimation algorithm is Full Search, Three-Step Search, Diamond Search and so on. We will optimize the Three-Step Search and the Diamond Search. IBM Cell platform architecture with a PPE and eight SPE is a heterogeneous type multi-core system. It can be thread-level and data-level to a high degree of parallel processing, and has a rapid memory parallel system of information processing demand for data bandwidth problem. In addition, IBM provides a very convenient virtual platform, so we have chosen to explore as a means of bringing the platform. In this paper, the best way to optimize the algorithm is based on characteristics of Cell processor such as the and high-speed data channel, vector instructions, NUMA (Non-Uniform Memory Access) the heterogeneity of multi-core architecture, the design of multiple buffering of DMA (Direct Memory Access) mechanisms and using vector SIMD computer mechanism to replace the original scalar computing mechanism and to reduce the number of branch instructions to avoid causing the penalty due to branch miss. Based on the acceleration of the above mechanism, we design algorithms for motion estimation in the use of CIF image size and the use of reference images of five cases the experimental results can be achieved for each image processing speed of 13.26ms.

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains viii, 111 p. Includes abstract. Includes bibliographical references (p. 109-111).

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2001. / "Funding was provided by the Office of Naval Research under grant N00014-01-1-0257 and the WHOI Education Office." "June, 2001." Includes bibliographical references (p. 207-215).