We show that inserting pilot tones with frequency intervals inversely proportional to the subcarrier index exhibits greatly improved dispersion estimation performance when compared to the equal spacing design in optical fast orthogonal frequency division multiplexing (F-OFDM). With the proposed design, a 20-Gbit/s four amplitude shift keying optical F-OFDM system with 840-km transmission withou...

As a generalization of orthogonal frequency-division multiplexing (OFDM) systems, multi-input multi-output (MIMO) OFDM systems are very sensitive to carrier frequency offset (CFO). This paper proposes a blind CFO estimation method based on power spectrum analysis, which has high bandwidth efficiency and is much less complex. This method can be used to estimate the residual CFO, which is less th...

In this paper, we consider the Type-II Hybrid ARQ schemes with the LDPC codes having the rate of 0.5 through MIMO-OFDM Spatial Multiplexing (SM) schemes for high speed and high throughput transmission. MMSE nulling and MLD are used for the signal separation and detection method in SM. We also have used the channel estimation per subcarrier with MMSE criterion. The uncoded Hybrid ARQ schemes wit...

Orthogonal Frequency Division Multiplexing (OFDM) is one of the techniques against the multipath fading channel for wireless communications. However, the high Peak-to-Average Power Ratio (PAPR) problem of OFDM is a major drawback of multicarrier transmission system which leads to power inefficiency in RF section of the transmitter. This paper presents different PAPR reduction techniques with an...

Conventional orthogonal frequency-division multiplexing receivers disregard the guard interval in channels with small dispersion even though its unconsumed portion can be exploited for improved demodulation by applying a Nyquist-shaped window in the receiver. The transmitter does not need to be modified, subcarrier orthogonality in the receiver is preserved, and the receiver discrete Fourier tr...

We experimentally demonstrate the superior performance of a 40-Gbps 16-QAM half-cycle Nyquist subcarrier modulation (SCM) transmission over a 100-km uncompensated standard single-mode fiber using dual-drive Mach-Zehnder modulator-based vestigial sideband intensity modulation and direct detection. The impact of modulator chirp on the system performance is experimentally evaluated. This Nyquist-S...

In this paper a complete analytical model for BER (Bit Error Rate) calculation of OFDM (Orthogonal Frequency Division Multiplexing) system with polarization diversity is presented. The assumed system consists of one transmit and dual polarized receive antenna. Propagation environment is characterized with Ricean fading and novel method for analytical determination of the system BER performance ...

I. INTRODUCTION Orthogonal frequency-division multiplexing (OFDM) [1] is one of the promising techniques for very high-speed data transmissions in a severe frequency-selective fading channel [2]. However, since OFDM uses a numerous number of narrowband orthogonal subcarriers to transmit data in parallel, the problem of high peak-to-average power ratio (PAPR) arise. To alleviate the PAPR problem...

Low-cost, high-capacity optical transmission systems are required for metropolitan area networks. Direct-detected multi-carrier systems are attractive candidates, but polarization mode dispersion (PMD) is one of the major impairments that limits their performance. In this paper, we report the first experimental analysis of the PMD tolerance of a 288Gbit/s NRZ-OOK Coherent Wavelength Division Mu...