Yuan-Hwui Chung

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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 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)
In this paper, we study the estimation of carrier frequency offset (CFO) in the presence of the receiver in-phase and quadrature-phase (I/Q) imbalance for orthogonal frequency division multiplexing (OFDM) systems. By minimizing the energy of the samples on the virtual subcarriers, our proposed algorithm can jointly estimate the CFO and I/Q parameters using(More)
In this paper, we study the channel estimation in the presence of the receiver in-phase and quadrature-phase (I/Q) imbalance and carrier frequency offset (CFO) for orthogonal frequency division multiplexing (OFDM) systems using pilot symbols. The concept of channel residual energy (CRE) [9] is used to solve the joint estimation problem. By minimizing the(More)
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)
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)