In this paper, it is proposed to enhance coherent optical orthogonal frequency-division multiplexing (OFDM) system by using index modulation in terms of bit error rate (BER) and spectral efficiency for different levels the fiber nonlinearity. OFDM with (CO-OFDM-IM), information conveyed not only through activated subcarriers but also indices active subcarrier that are dynamically updated at tra...

In this chapter, we propose two novel peak-to-average power ratio (PAPR) reduction schemes for the asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) scheme used in the visible light communications (VLC) system. In the first scheme, we implement the Toeplitz matrix based Gaussian blur method to reduce the high PAPR of ACO-OFDM at the transmitter and use the ort...

This paper results clipping and filtering technique for peak to average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM). Our simulation results show that this technique removes inband and out of band distortion along with 1dB reduction in peak to average power ratio when crest ratio changes from 1.4 to 1.2. KeywordsClipping, Crest ratio, Orthogonal frequency di...

The complementary M-ary orthogonal spreading with frequency division multiplexing (CMOS-OFDM) is an efficient scheme for providing high bit error rate (BER) performance and low peak to mean envelop power ratio (PMEPR) in (HF) communications system. In the CMOS-OFDM, OFDM implemented based on sequence pairs where there issue that one data symbol transmitted through two symbols. this paper, we pr...

Orthogonal frequency division multiplexing (OFDM) combined with time division multiplexing (TDM) bridges the conventional OFDM and single carrier (SC) transmission. For a coded OFDM/TDM system with frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion in a frequency-selective fading channel, there is a trade-off between coding gain and frequency diversity effec...

The Performance of the Orthogonal Frequency Division Multiplexing (OFDM) systems degrade due to Doppler frequency or frequency drift between transmitter and receiver oscillator which causes frequency offset and hence leads to a number of impairments in the received signal, thereby making its detection incorrect. In this paper, a threshold-based frequency offset estimation algorithm for orthogon...

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...

Abstract: For alleviating the high peak-to-average power ratio (PAPR) problem of orthogonal frequency division multiplexing (OFDM) while improving the bit error rate (BER) performance, the OFDM combined with time division multiplexing (TDM) using frequency-domain equalization (FDE) is proposed. In this paper, the theoretical BER analysis of the OFDM/TDM in a frequency-selective fading channel i...

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 wireless system for communication uses the orthogonal frequency division multiplexing in these days. The rapid growth of high data rate transmission makes a need to improve the performance of a network. This can be made easy by using Orthogonal Frequency Division Multiplexing. OFDM is an approach in which the multicarrier transmission technique has been used for wireless communication. Here...