| Summary: | 碩士 === 淡江大學 === 電機工程學系碩士班 === 98 === The geometrical shape of antenna arrays for maximizing the average channel capacity of the system in a multiple-input multiple-output (MIMO) link is investigated. The optimum element spacing of the transmitting antenna is also included. In this paper, channel capacity of multiple-input multiple-output narrowband system in indoor wireless channels at 5-GHz U-NII (Unlicensed-National Information Infrastructure) bands is calculated. An optimization procedure for the element spacing of the antenna transmitter in narrowband wireless communication system is presented. The frequency responses of different transceiver antenna element spacing are computed by shooting and bouncing ray/image (SBR/Image) techniques, and the channel frequency response is further used to calculate corresponding channel capacity. The transmitter is in the center of the indoor environment and the receivers are uniform intervals distribution, which 150 measurements with 0.25m intervals in the whole wooden table in indoor environment. And the inter-element separation of Receiver antennas (Rx) is 0.03m. Linear shaped array, L shaped array, T shaped array and rectangular shaped array geometries with non-uniform inter-element spacing are investigated for both line-of-sight (LOS) and non-LOS (NLOS) scenarios. The optimal element spacing of antenna for maximizing the channel capacity is searched by dynamic differential evolution (DDE). Numerical results have shown that our proposed method is effective for increasing average channel capacity. It is also found that L shaped array has the highest channel capacity and the improvement ratio for rectangular shaped array is largest.
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