| Summary: | 碩士 === 國立中興大學 === 電機工程學系 === 90 === We propose a multi-user detection scheme for downlink channel and uplink link channel, including multi-path effect. The Quasi-Decorrelating detector (QDD) is a linear detector but the decorrelating algorithm is performed without inverse matrix transform, as an effort to overcome the problem associated with the DD.
The QDD can be implemented by multi-stage feed-forward filters, the number os which can be made scalable to trade MAI suppression for noise enhancement reduction according to varying channel conditions. On the contrary, the DD has a rigid structure and is unable to adapt to changing operation environment.
For downlink channel, we considering the multi-path and fading effect, and we assume that there are 12 kinds of channels to simulation. To improve the system performance, two different types of RAKE receiver structures, equal gain combining RAKE and maximum ratio combining RAKE, are also considered for CDMA systems to mitigate multi-path fading effects of mobile channels. For uplink channel, the assumption are the same with downlink channel, the different is just the users are asynchronous each other.
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