In this paper, we investigate channel estimation algorithms in an OFDM system which is exposed to pulsed interference. It will be examined how the interference affects the performance of the channel estimation and how the channel estimation can be adapted to cope with the interference. The performance of the channel estimation will be given by means of the mean square error. In addition, bit er...

OFDM is being widely used in many communication systems for its ability to enhance the data rate and reduce the bandwidth. The paper gives a comparison of the performance of OFDM system using different modulation schemes under the influence of AWGN and Rayleigh fading channel. Simulations of OFDM signals are carried out with Rayleigh faded signals to understand the effect of channel fading and ...

In this paper, we consider orthogonal space-frequency transmit diversity schemes for OFDM systems in broadband wireless channels. We propose a compensation method to prevent error floor caused by unequal subchannels in the space-frequency block coded OFDM systems for 2 and 3 transmit antennas while providing diversity gain. We will show that for 2 antennas case, the proposed compensation method...

Non-orthogonal multiple access (NOMA) is deemed to be a prospective technology of the next generation. However, in visible light communication (VLC), when advanced hybrid optical orthogonal frequency division multiplexing (O-OFDM), such as asymmetrically clipped O-OFDM (HACO-OFDM), combined with NOMA, error propagation induced, which degrades system performance. Therefore, novel reconstructed O...

In the mobile radio environment, signals are usually impaired by fading and multipath delay phenomenon. In such channels, severe fading of the signal amplitude and inter-symbol-interference (ISI) due to the frequency selectivity of the channel cause an unacceptable degradation of error performance. Orthogonal frequency division multiplexing (OFDM) is an efficient scheme to mitigate the effect o...

Abstract Intensity Modulated (IM) optical communication over an LED channel requires the use of a non-negative signal that can also cope with low-pass nature LEDs. For this purpose, dedicated schemes such as Flip-OFDM and Assymetrically Clipped Optical (ACO)-OFDM have been proposed. We derive common mathematical description on which both rely. Exploiting insight, we propose Continuous Phase (CP...

In this paper we compare the performance of OFDM with a cyclic prefix (CP) and isotropic orthogonal transform algorithm (IOTA) OFDM without cyclic prefix under typical system imperfections such as channel estimation errors and frequency offset. The IOTA-OFDM system is based on offset quadrature amplitude modulation (OQAM) and promises an increased immunity to both inter-carrier interference (IC...

This paper proposes an efficient scheme to track the time variant channel induced by multi-path Rayleigh fading in mobile wireless multiple input multiple output–orthogonal frequency division multiplexing (MIMO–OFDM) systems with null sub-carriers. In the proposed method, a blind channel response predictor is designed to cope with the time variant channel. The proposed channel tracking scheme c...

Orthogonal Frequency Division Multiplexing (OFDM) is a promising technique for high data rate wireless communications because it can combat inter-symbol interference caused by the dispersive fading of wireless channels. A FDM channel is like water flow out of a faucet, in contrast the OFDM signal is like a shower. In a faucet all water comes in one big stream and cannot be subdivided. OFDM show...

This paper deals with synchronization and channel estimation in a filtered multitone (FMT) modulated system. An FMT based system differs from the popular OFDM scheme in the deployment of sub-channel shaping filters. Although the synchronization problem in OFDM is well understood, in an FMT system it presents several challenges. The approach herein presented is based on the deployment of appropr...