| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 91 === In the thesis, we build up the channel model of multiple input and multiple output wireless communication system, and compare the noise performance between the close-loop transmit model and the open-loop transmit model. Since close-loop transmit diversity is applied especially in low mobility environment, it have inferior performance than those with single antenna. This is due to the fact that feedback channel parameters can’t reflect channel immediately in high mobility environment. Although the performance of the open-loop transmit diversity is inferior compared to that of the close-loop one, this scheme is with has lower complexity and is easier to implement.
In order to improve the noise performance of the open-loop transmit model, we employ the space-time spreading technique (STS), which improve the diversity gain both in space and time domain. But in reality of channel transmit model, the angle spread and the antenna spacing correlate due to the fact of the time-domain correlation between Doppler spread and the delay spread. We analyze the noise performance space-time spreading technique in non-independent channel environment. The insufficiency of time diversity in space-time spreading technique is also investigated by simulation. We also incorporate the Time Division Duplexing (TDD) concept to the space-time spreading technique, and then form a modified space-time spreading technique. The noise performance of the space-time coding technique (STC) is also analyzed for various scenarios. We observe from the results of simulations, that the modified space-time spreading technique has better performance in any abominable environment.
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