OFDM and its extension Multi-band OFDM (MB-OFDM) are considered as the modulation schemes for many future communications systems. But these schemes cause high PAPR which should be reduced before power amplification otherwise non-linearities can occur. In this paper Tone Reservation method is used for OFDM PAPR reduction where a corrective signal is added to the original signal to reduce its PAP...

Orthogonal frequency-division multiplexing (OFDM) with multiple transmit and multiple receive antennas (MIMO-OFDM) is considered a candidate for high-data rate communication in various existing and forthcoming system standards. To achieve the usually desired low frame and bit error rates, MIMO-OFDM should be combined with adaptive bit loading (ABL) and forward error correction (FEC) coding, whe...

We present the performance of OFDM systems with coding, spreading, and clipping. Low-Density Parity-Check (LDPC) codes give coding gains and spreading by the Walsh Hadamard transform gives gains in terms of increased frequency diversity as well as reduced peak-toaverage power ratio (PAPR) of the transmitted OFDM signal. By evaluating both the IFFT transform (OFDM) and the Walsh Hadamard transfo...

This paper compares the performance of a Turbo coded OFDM wireless link for SISO, SIMO, MISO and MIMO system with uncoded OFDM wireless link for SISO, SIMO, MISO and MIMO system in the in the presence of rayleigh fading. Turbo encoder encodes the input information bits and sends to QPSK or 16 QAM or 64 QAM modulator. Modulated symbols are mapped by STBC. Outputs of STBC are split into n streams...

Recently, the demand of high-speed network in home is increasing. PLC (Power Line Communication) is expected as one method of realizing it. OFDM is one of the methods, which realizes high-speed PLC. But the minimum stopband attenuation of OFDM modulation is only -13dB. It indicates that OFDM subchannels are not spectrally isolated, therefore OFDM is sensitive to the locations of narrow band int...

Preamble design for LS channel estimation in OFDM/OQAM cooperative systems is investigated in this paper. A simple but important setup is considered, consisting of a pair of single-antenna terminals (source and destination) assisted in their communication by an AF relay and following a well-established two-phase transmission protocol. The so-called sparse preamble case (i.e., pilot tones surrou...

Constant-power adaptive transmission technique adopting UL-coded spectrally-precoded orthogonal frequencydivision multiplexing (SP-OFDM) signals with one tap zeroforcing equalization is studied on the flat fading channel. By jointly adapting the precoding order for spectral precoder and the component modulation for OFDM, constant-power ULcoded adaptive SP-OFDM is shown to outperform conventiona...

With its robustness against multipath fading, orthogonal frequency division multiplexing (OFDM) has become the modulation of choice for many modern wireless standards. However, OFDM is very sensitive to offsets in frequency and time. This makes synchronization an essential part of an OFDM system. This paper aims to motivate and analyze past work on OFDM synchronization techniques.

The popular modulation scheme which offers reliable high bit rate wireless system with reasonable complexity is Orthogonal Frequency Division Multiplexing (OFDM). OFDM is preferred in most high bandwidth efficient transmission systems because it effectively resists Intersymbol Interference (ISI) and is robust towards multipath fading. One of the main factor affecting the performance of an OFDM ...

We propose a four-dimensional (4D) coded multiband-OFDM scheme suitable for beyond 1.4 Tb/s serial optical transport. The proposed scheme organizes the N-dimensional (ND) signal constellation points in the form of signal matrix; employs 2D-inverse FFT and 2D-FFT to perform modulation and demodulation, respectively; and exploits both orthogonal polarizations. This scheme can fully exploit advant...