Rapid time variations of the mobile communication channel have a dramatic effect on the performance of multicarrier modulation. This paper models the Doppler spread and computes its effect on the bit error rate (BER) for multicarrier code division multiple access (MC-CDMA) transmission and compares it to orthogonal frequency division multiplexing (OFDM). Also, we evaluate the transmission capac...

In this paper, Optimum adaptive loading algorithms are applied to Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMOOFDM) system. Chaw’s and Compello’s algorithms have been implemented to obtain a bit and power allocation for each subcarrier assuming instantaneous channel knowledge. Channel matrix singular value decomposition (SVD) method has been employed in MIMO-O...

Inter-carrier Interference (ICI) is a severe problem in orthogonal frequency division multiplexing (OFDM) systems. Any offset between the subcarrier frequencies of the transmitter and receiver ruins the orthogonality of OFDM subcarriers and introduces ICI to an OFDM system. There are various methods to mitigate the effects of ICI. In this paper various ICI self-cancellation (ICI-SC) techniques ...

In this paper, we propose the new technique adopting power control to MIMO(multi-input multi-output)OFDM(orthogonal frequency division multiplexing) system with multi-beamformer. Through the proposed technique, we can iteratively control the transmitting power and update the weight of beamformer simultaneously. Therefore, the beam is formed toward the desired direction and the SNIR at each subc...

This paper investigates the effects of phase noise on the performance of Orthogonal Frequency Division Multiplexing (OFDM) systems using an Intercarrier Interference (ICI) cancellation scheme. In this case, the Common Phase Error (CPE) and ICI caused by phase noise depend on the overall spectrum of each weighted group of subcarriers rather than on the spectrum of each individual subcarrier. Thi...

A novel Orthogonal Frequency Division Multiplexing detection technique compatible to standard (e.g. Wireless LAN) transmitters is proposed. It features enhanced error-rate performance with flexible computational complexity and robustness to imperfect channel estimation. It is based on exploitation of the redundancy available in the cyclic prefix after cancellation of interference from the prece...

The flexible adaption of the transmission scheme to the current channel state becomes more and more a key issue in future communication systems. One efficient solution in multicarrier systems like Orthogonal Frequency Division Multiplexing (OFDM) has been proven to be adaptive modulation (AM) where the modulation scheme is selected on a subcarrier-basis or group of subcarriers. A lot of researc...

This paper proposes a blind multiuser detection and channel estimation method for multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems based on blind source separation (BSS). Using multiple antennas for transmission and reception the multiuser detection problem can be cast as a BSS problem of linear instantaneous mixtures. The proposed method uses BSS ...

Orthogonal Frequency Division Multiplexing (OFDM) is multicarrier modulation scheme for combating channel impairments such as severe multipath fading and impulsive noise. However, the principal disadvantage of OFDM is that it is highly susceptible to carrier frequency offset (CFO). Carrier frequency offset occurs due to frequency discrepancies between transmitter and receiver and Doppler shift ...

We address the problem of carrier frequency offset (CFO) synchronization in Orthogonal Frequency Division Multiplexing (OFDM) communications systems in the context of frequency-selective fading channels. The mathematic model of OFDM systems with cyclic prefix (CP) and virtual subcarrier is derived. And we propose the shift-invariance CFO estimation algorithm based on DOA-MATRIX method. After th...