| Summary: | 博士 === 國立中正大學 === 電機工程研究所 === 99 === In this dissertation work, two wireless indoor positioning systems aiming for decimeter positioning accuracy, low circuit complexity, and multipath suppression, were investigated and developed. In both systems, only the received signal strength (RSS) information is required for the target’s direction-of-arrival (DOA) estimation so that the system complexity as well as infrastructure cost can be significantly reduced. However, large positioning error could occur due to the multi-path fading effect on the received signal strength. Therefore, the indoor multipath channel modeling for linear and planar array was also derived mathematically. To eliminate the multipath signals, two positioning technologies were proposed, including the non-orthogonal beamforming and the selection-and-average error correct algorithm.
The first wireless indoor positioning system based on the non-orthogonal beam linear arrays was implemented by incorporating two linear array receivers to determine the position of target. The circular-polarized antenna array with high directivity was chosen to suppress the multipath interference. In addition, the beam orthogonality was demoted on purpose so that the angular position can be estimated based on the power ratio of two adjacent beams.
The second wireless indoor positioning system was implemented by using a 2×2 planar array with the selection-and-average error correction algorithm. The multiple power ratio detection curves were generated due to the beam steering, while the selection-and-average error correction algorithm was proposed to improve the location accuracy. The proposed 2-D precise DOA estimation can be achieved by 1-D pattern calibrations in two axils only.
Additionally, numerous tunable phase shifter MMICs, which are the essential component in phased array system, were designed and implemented aiming for low loss-variation performance over quadrants of phase-shift range. The inductively over-coupled quadrature hybrids were theoretically analyzed, such that the phase, amplitude imbalance, and circuit size can be significantly reduced. During the course of this work, four phase shifters MMICs designed at 2.45, 24, and 60 GHz were implemented in 0.18-um CMOS technology.
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