This paper proposes an efficient transmission scheme, Quasi-Orthogonal Time Division Multiplexing (QOTDM), which employs the shift orthogonal property of the pulse function with raised-cosine spectral shape, and the signal waveforms are quasiorthogonal in time domain. Comparing to orthogonal frequency division multiplexing (OFDM), QOTDM is less sensitive to carrier frequency offset and power am...

Abstract— In this paper, we propose the use of verticalBell Labs layered space-time (V-BLAST) detection for orthogonal frequency division multiplexing code division multiplexing (OFDM-CDM) systems. Considering the properties of the VBLAST detection as well as the frequency diversity from CDM, we propose a new CDM transform matrix to improve the performance of V-BLAST detection of OFDM-CDM signa...

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.

Recently, orthogonal frequency division multiplexing (OFDM) techniques have received great interest in wireless communications for their high speed data transmission. OFDM improves robustness against narrowband interference or severely frequency-selective channel fades caused by long multipath delay spreads and impulsive noise. A single fade or interferer can cause the whole link to fail in a s...

In several wireless communication systems and standards, Orthogonal Frequency Division Multiplexing (OFDM) is used widely due to its high spectral efficiency, high data rate, multipath delay spread tolerance, power efficiency, robustness to multipath fading channels and immunity to the frequency selective fading channels. However, the main challenge for OFDM system implementation is high PAPR, ...

Orthogonal frequency division multiplexing (OFDM) is a special case of multicarrier transmission, where a single data stream is transmitted over a number of lower rate subcarriers. Orthogonal frequency division multiplexing (OFDM) has been chosen as modulation technique for different application wireless communications. OFDM can provide large data rates with sufficient robustness to radio chann...

Orthogonal Frequency Division Multiplexing (OFDM) is an efficient method of data transmission for high speed communication systems. However, the main drawback of OFDM system is the high Peak to Average Power Ratio (PAPR) of the transmitted signal. OFDM consist of large number of independent subcarriers, as a result of which the amplitude of such signal can have high peak values. Pulse shaping u...

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...

Orthogonal frequency division multiplexing (OFDM) is a multi-carrier transmission technique that has been recently recognized as an excellent method for high speed bi-directional wired/wireless data communication. High capacity and variable bit rate information transmission with high bandwidth efficiency are just some of the requirements that the modern transceivers have to meet in order for a ...

---------------------------------------------------------------------***----------------------------------------------------------------Abstract –Orthogonal Frequency Division Multiplexing (OFDM)is the promising candidate of a multiple carrier modulation technique because it does not require equalizers. OFDM is robust in adverse channel conditions and allows a high level of spectral efficiency....