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...

N-continuous orthogonal frequency division multiplexing (NC-OFDM) is a promising technique to achieve significant sidelobe suppression of baseband OFDM signals. However, the high complexity limits its application. Based on conventional NC-OFDM, in this paper, a new technique, called time-domain N-continuous OFDM (TD-NC-OFDM), is proposed to transfer the original frequency-domain processing to t...

This paper investigates the performance of MultipleInput Multiple-Output (MIMO) feedback system combined with Orthogonal Frequency Division Multiplexing (OFDM). Two types of codebook based channel feedback techniques are used in this work. The first feedback technique uses a combination of both the long-term and short-term channel state information (CSI) at the transmitter, whereas the second t...

Problem statement: MB-OFDM UWB systems have attractive features and received a great attention. It has the capability of sending/receiving data at rates in access of 100 Mbits sec. Owing to the sensitivity of OFDM systems to synchronization errors, a fast synchronization algorithm is required to discern for the start of OFDM symbol. Existing approaches to OFDM time synchronization rely on their...

In this paper an attempt is made to study the theoretical fundamentals for Coherent optical orthogonal frequency division multiplexing (CO-OFDM) for high speed, long haul optical transmission and investigated the nonlinear effect of a 16-QAM CO-OFDM and WDM CO-OFDM at 10Gbps data rate. We then demonstrated the transmission performance through simulation for single channel COOFDM and multi-chann...

OFDM offers many advantages in terms of resilience to fading, reflections and the like. OFDM also offers a high level of spectrum efficiency. However to reap the rewards, it is necessary that the OFDM system operates correctly, and to achieve this, it is necessary for the OFDM synchronization to be effective. There are a number of areas in which the OFDM synchronization is critical to the opera...

High Peak-to-Average Power Ratio (PAPR) is one of the major drawback of Orthogonal Frequency Division Multiplexing (OFDM) based systems that can cause intermodulation among the subcarriers due to the nonlinearities of the fiber. The high PAPR increases the complexity of the Analog to Digital (A/D) and Digital to Analog (D/A) converters. In this paper, I present an analysis of Discrete Fourier T...

In this paper, a new adaptive transmit diversity selection (ATDS) scheme is proposed for future wireless communication system to provide high spectral efficiency (SE) and good quality of service (QOS) .The ATDS scheme selects the space time block code (STBC) orthogonal frequency division multiplexing (OFDM) scheme for flat fading channel and it selects space frequency block code (SFBC) OFDM sch...

Polynomial cancellation coding (PCC) is a method of mapping data onto the subcarriers of OFDM which results in reduced sensitivity to frequency offset. [1] – [4]. In this paper it is shown that the amplitude statistics for PCC OFDM are different from ordinary OFDM and the statistics are not Gaussian. The results of simulations for OFDM and PCC OFDM are presented. It is shown that the signal sta...

This paper investigates performance degradation of conventional Orthogonal Frequency Division Multiplexing (OFDM) and Discrete Wavelet Transform based OFDM (DWT-OFDM) systems when the signals are passed through a nonlinear High Power Amplifier (HPA) and fading channel. In the case of DWT-OFDM, several wavelets such as Daubechies, Symlet and Biorthogonal are evaluated. Simulation results in term...