In this paper, we will focus on channel estimation (CE) in orthogonal frequency-division multiplexing (OFDM) systems. The time-varying (TV) channels are modeled by a basis expansion model (BEM). Due to the time-variation, the channel matrix in the frequency domain is no longer diagonal, but approximately banded. We use a pilot-aided algorithm for estimation of rapidly varying wireless channels ...

Abstract: Orthogonal frequency division multiplexing combined with time division multiplexing (OFDM/TDM) was proposed to overcome the high peak-to-average-power ratio (PAPR) of conventional OFDM. Clipping and filtering can be used to further reduce the PAPR. OFDM/TDM with minimum mean square error (MMSE) frequency-domain equalization (FDE) requires accurate channel estimation (CE). In this pape...

—Orthogonal Frequency Division Multiplexing (OFDM) has been a popular scheme for digital communication systems, which is widely used in digital television and audio broadcasting, wireless networks, powerline networks, and the Fourth Generation (4G) mobile communications. In OFDM scheme, channel estimation is a necessary technique for improving the system’s performance. Linear Least Square (LLS...

The Digital Video Broadcasting (DVB) project has developed digital broadcasting system specifications which have been adapted worldwide. The family of DVB standards includes DVB-S for satellite, DVB-C for cable and DVB-T for terrestrial system. This DVB-T system has proven its capability and thus accepted as the standard for terrestrial system in m o s t c o u n t r i e s. D V B-T 2 i s t h e e...

Alomouti’s space-time coding scheme for Multi-Input Multi-Output (MIMO) system has drawn much attention in 4G wireless technologies. Orthogonal frequency division multiplexing (OFDM) is a popular method for high data rate wireless transmission. OFDM may be combined with antenna arrays at the transmitter and receiver to increase the diversity gain and enhance the system capacity on time variant ...

The goal of this contribution1 is twofold: i) an overview on the vast literature on recent advances related to OFDM modulators is given: Cyclic-Prefix OFDM, Zero-Padded OFDM, PseudoRandom-Postfix OFDM and IOTA-OFDM; these are identified to be potential candidates for fourth generation mobile communication networks in the framework of the IST-WINNER project. ii) The advantages/disadvantages of t...

In this paper, we study the channel estimation in the presence of the receiver in-phase and quadrature-phase (I/Q) imbalance and carrier frequency offset (CFO) for orthogonal frequency division multiplexing (OFDM) systems using pilot symbols. The concept of channel residual energy (CRE) [9] is used to solve the joint estimation problem. By minimizing the CRE, we can jointly estimate the receive...

OFDM combined with TDM (OFDM/TDM) can be used to reduce a high peak-to-average power ratio (PAPR) of OFDM, but the PAPR reduction is not sufficient. To further reduce the PAPR, an amplitude clipping can be applied. In this letter, we investigate the effect of clipping on OFDM/TDM with and without channel coding. It is shown that amplitude clipped OFDM/TDM has an advantage over clipped OFDM with...

In wireless communication, multiplexing & multiple access concept is most important. In most communication systems require, sharing of channels. In Multiple Access techniques types such as FDMA, TDMA, CDMA, & OFDM. OFDM based transmission system uses CP in an MB-OFDM symbol in order to maintain the orthogonality of Trasmission.Present days ultra-wideband systems use multi-band OFDM techniques f...

Due to the high spectral efficiency (SE) and fast synchronization, time-domain synchronization orthogonal frequency division multiplexing (TDS-OFDM) system has gotten much more attraction of researchers as compared cyclic-prefix (CP) zero padding (ZP) OFDM in terrestrial well underwater acoustic communication. Inter-block interference (IBI) degrades TDS-OFDM performance due its long-delay multi...