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In all-optical orthogonal frequency division multiplexing (AO-OFDM) systems, symbol time misalignment (STM) and subcarrier frequency offset (ScFO) result in intercarrier-interference and intersymbol interference, leading to degradation of bit error rate (BER) performance. In this study, an analytical study of the impacts of STM and ScFO on AO-OFDM system performance is conducted. In the presence of...
We present an improved estimator of the phase noise θ(t) in OFDM systems, based on the approximation of the time-varying phasor exp(jθ(t)) by a discrete-cosine transform (DCT) basis expansion, containing only a few terms. Using pilot symbols, an initial least-squares estimate of the phase noise is obtained. The initial estimate is iteratively improved by also exploiting the soft decisions from the...
A distortion-compensation scheme is proposed for the PAPR reduction of orthogonal frequency division multiplexing (OFDM) signal. In the transmitter, clipping the peak envelope of the input signal to a predetermined value will cause in-band distortion. This distortion is encoded as clipping information and transmitted in the next block. In the receiver, the in-band distortion is compensated by the...
It is conventionally supposed that the periodicity of superimposed training (ST) sequence designed for channel estimation has no impact on the ST system's performance, as long as the channel identification condition is satisfied. Accordingly the shortest sequence period equal to channel length is always preferred in ST-OFDM systems for its computational tractability. However, with additional consideration...
Wavelet Packet Modulation (WPM) is a novel multicarrier modulation (MCM) technique and a promising alternative to the well established OFDM. However a few key research questions remain to be addressed before WPM can become practically viable. One of them is their sensitivity and vulnerability to time synchronization errors. This is particularly interesting because WPM symbols overlap in the time domain...
This paper proposes a new system called the collision-captured multicarrier modulation system which can realize the capture of a packet collision. Based on the OFDM system using partial symbol transmission, the transmitter can select a specific duration to achieve promising PAPR characteristics and realize the capture of a packet collision. The simulated results show that over 90% collision occurrences...
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