Chun-Jung Wu

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Time-domain channel estimation techniques have been proposed for OFDM systems for their ability to yield relatively accurate estimates with only a few pilots. Key information needed in such techniques is the multipath delays of the channel. Prior approaches to estimation of multipath delays require regular pilot structures and may not work in slow fading.(More)
In channel estimation for OFDM transmission over sparse channels, the time-domain approach requires estimation of much fewer parameters than the frequency-domain approach, but one needs to estimate both the delay and the gain of each path. We consider the time-domain approach and propose an algorithm that finds a set of delays under a certain criterion on(More)
We consider the design of a multi-input multi-output (MIMO) transmission system equipped with distributed, single-antenna amplify-and-forward relays. In particular, we consider how to optimize the complex forwarding coefficients of the relays to maximize the system capacity. Existing studies on MIMO relay network designs mostly concentrate on the case of(More)
Relays can potentially enhance the transmission performance of multi-input multi-output (MIMO) systems. A parallel single-antenna relay network has additional advantages in flexibility, diversity and cost, but also poses significant design problems because the absence of inter-antenna connections over different relays makes the underlying mathematical(More)
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