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...

In this paper, a new peak-to-average power ratio (PAPR) reduction scheme for orthogonal frequency division multiplexing (OFDM) is proposed based on the selected mapping (SLM) scheme. The proposed SLM scheme generates alternative OFDM signal sequences by cyclically shifting the connections in each subblock at an intermediate stage of inverse fast Fourier transform (IFFT). Compared with the conve...

The resource allocation in multiuser Orthogonal Frequency Division Multiplexing (OFDM) systems is addressed, which aims to maximize the user-perceived quality of services instead of the conventional objective metrics. By introducing the previous application-centric Mean Opinion Score (MOS) assessment model, the problem is formulated as a bounded optimization problem, which is non-concave and di...

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...

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...

Orthogonal frequency division multiplexing (OFDM) is a popular method for high data rate wireless transmission. OFDM is combined with antenna to increase the diversity gain to enhance the system capacity on time-variant and frequency-selective channels, resulting in a multiple-input multiple-output (MIMO) configuration. To better handle fading channel, Space frequency block code (SFBC) MIMO-OFD...

Space-frequency coded Orthogonal Frequency Division Multiplexing (OFDM) is capable of realizing both spatial and frequency-diversity gains in multipath multiple-input multipleoutput (MIMO) fading channels. This naturally leads to the question of variable allocation of the channel’s degrees of freedom to multiplexing and diversity transmission modes. In this paper, we provide a systematic method...