Visible light communication (VLC) system for small range transmission uses visible spectrum which provides illumination simultaneously. Designing cost of light emitting diodes was reduced in order to make this communication possible. A modulation technique which can effectively employ the bandwidth is orthogonal frequency division multiplexing (OFDM) technique. This technique has a unique form ...

Background: Orthogonal frequency division multiplexing has been regarded as one of the promising technologies for the optical access systems application. However, high peak-to-average power ratio will cause the signal distortion and enable the used amplifier to operate in nonlinear section. Methods: In this paper, a modified selected mapping technique is introduced for reducing the peak-to-aver...

Orthogonal Frequency Division Multiplexing (OFDM) is multiplexing technology of orthogonal multicarrier, and the channel estimation model based on pilot in OFDM systems is analyzed; Now that, the channel estimation based on pilot needs interpolation, in order to reduce the complexity of the interpolation algorithm, the FFT channel estimation algorithm based on pilot is studied. Because of the d...

The main limitation in employing orthogonal frequency division multiplexing (OFDM) system is high peak-toaverage power ratio (PAPR) of the transmitted signal. A new nonlinear companding algorithm that transforms the OFDM signals into the desirable statistics form defined by a linear piecewise function is proposed. The more adjustability in companding form and an effective trade-off between the ...

In Orthogonal Frequency Division Multiplexing (OFDM) systems, the peak to average power ratio (PAR) is much high. The clipping signal scheme is a useful method to reduce PAR. Clipping the OFDM signal, however, increases the overall noise level by introducing clipping noise. It is necessary to recover the figure of the original signal at receiver in order to reduce the clipping noise. Considerin...

Orthogonal Frequency Division Multiplexing (OFDM) is sensitive to the carrier frequency offset (CFO). We introduce the Peak Interference-to-Carrier Ratio (PICR) to measure the resulting intercarrier interference (ICI). This paper shows that PICR can be reduced by Partial Transmit Sequence (PTS) and Selected Mapping (SLM) approaches. In PTS, each block of subcarriers is multiplied by a constant ...

This paper provides a novel orthogonal frequency division multiplexing (OFDM), called orthogonal frequency division multiplexing with index modulation (OFDM-IM). In this scheme the information is conveyed not only by M-ary signal constellations but also by the indices of the sub carriers. The error performance analysis is provided for this scheme operating under ideal channel conditions. Then t...

There has been greatly increasing interest in orthogonal frequency division multiplexing (OFDM) for broadband wireless transmission due to its robustness against multipath fading. However, OFDM signals have high peak-toaverage power ratio (PAPR), and thus, a power amplifier must be operated with a large input power backoff (IBO). Recently, OFDM combined with time division multiplexing (OFDM/TDM...

A carrier separated OFDM system is proposed to support high data rates in mobile multiple access environments. OFDM is considered to support high data rates and carrier separation is introduced to combat multipath fading. The performance is comparable to that of a frequency hopped OFDM system. While promising robustness against multipath fading, the computational complexity of a carrier separat...

In an Orthogonal Frequency Division Multiplexing (OFDM) systems, the Peak to Average power Ratio (PAR) is high. The clipping signal scheme is a useful and simple method to reduce the PAR. However, it introduces additional noise that degrades the systems performance. We propose an oversampling scheme to deal with the received signal in order to reduce the clipping noise by using finite impulse r...