Yuan-Hwui Chung

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In this paper, we study the joint estimation of I/Q imbalance, CFO and channel response for OFDM systems. Using two repeated OFDM blocks for training, we propose a new method to solve the joint estimation problem. The implementation complexity is low. Simulation results show that the proposed method has a good performance and its BER is very close to the(More)
In this paper, we first introduce a new method for joint estimation of IQ imbalance and channel response in OFDM systems under the assumption of perfect frame synchronization. The proposed method needs only one OFDM block for training and the solution is given in closed form. Then the method is applied to the scenario when the OFDM frame is not(More)
Discrete multitone (DMT) systems have been widely adopted in broadband communications. When the transmission channel is frequency selective, there will be interblock interference (IBI). IBI can be avoided by zero-padding (ZP) [1]. Another solution is to allow IBI during transmission, and at the receiver the samples that contain IBI are removed by(More)
—This paper studies unitary precoders for space-time coded orthogonal frequency division multiplexing (ST-OFDM) systems using Alamouti space-time block codes (STBC). We consider two channel models: 1) the LTI case where the channels are invariant for two consecutive OFDM blocks; 2) the time-varying case where the channels are invariant within one OFDM block(More)
In this paper, we consider channel estimation for orthogonal frequency division multiplexing (OFDM) systems when both the transmitter and receiver suffer from in-phase and quadrature-phase (I/Q) imbalance. By exploiting the fact that the block size of an OFDM system is usually larger than the channel order, we propose a new method which can jointly estimate(More)
In this paper, we study joint estimation of in-phase and quadrature-phase (I/Q) imbalance and channel response for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems using training sequence. A new class of optimal sequences, called circularly-shift orthogonal sequences, are introduced for estimating the MIMO(More)
In this paper a reduced-complexity partial transmit sequences (PTS) approach is proposed for the reduction of peak-to-average power ratio (PAPR) in OFDM systems. In the PTS scheme, we need several IFFTs (inverse fast Fourier transforms) to compute the partial transmit sequences. There are two main contributions in the paper. Firstly, we propose to partition(More)