Orthogonal multi-carrier direct sequence code division multiple access (orthogonal MC DS-CDMA) is a combination of time-domain spreading and orthogonal frequency division multiplexing (OFDM). In orthogonal MC DS-CDMA, the frequency diversity gain can be obtained by applying frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion to a block of OFDM symbols and can...

Recently, frequency-domain equalization (FDE) has been attracting much attention as a way to improve single-carrier (SC) signal transmission in a frequency-selective wireless channel. Since the SC signal spectrum is spread over the entire signal bandwidth, FDE can take advantage of channel frequency-selectivity and achieve the frequency diversity gain. SC with FDE is a promising wireless signal...

In this paper, we propose a joint carrier frequency synchronization and channel estimation algorithm for multipleinput and multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. A major challenge to MIMO-OFDM systems is how to obtain the channel state information accurately and promptly for coherent detection of information symbols and channel synchronization. MIMOOFDM ...

Wireless communication systems targeting at broadband and mobile transmissions commonly face the challenge of fading channels that are both time and frequency selective. Therefore, design of effective equalization and estimation algorithms for such channels becomes a fundamental problem. Although multi-carrier transmissions demonstrate prominent potential to combat doubly selective fading, seve...

For the purpose of various synchronization tasks (including carrier phase, time, frequency, and frame synchronization), one may add a known pilot sequence, typically a pseudo-noise sequence, to the unknown data sequence. This approach is known as a spread-spectrum pilot technique or as a superimposed pilot sequence technique. In previous work, we applied the superimposed pilot sequence techniqu...

~ince the Co.de Division Multiple Access (CDMA) system was proposed for the next generation of mobile communications, several multiuser detection· methods have been develope? to cope with the Multi-Access Interference inherent in the CDMA system. Fading and. multIpath ch~acteristi~sof the mobile radio channel present significant challenges to the designer of multiuser receivers. The fading phen...

Orthogonal synchronization has been a major problem in Cooperative Orthogonal Frequency Division Multiplexing (CO-OFDM) under the influence of both carrier frequency offset and timing offset with unknown channel gains. CO-OFDM network performance can be improved by employing Amplify-and-Forward (AF) relay strategy. The OFDM network comprises of many sub-carriers which requires an adjustment of ...

Generalized multi-carrier (GMC) CDMA transceivers equipped with frequency hopping are developed in this paper. Through judicious code design, multiuser interference (MUI) is eliminated deterministically and symbol recovery is guaranteed, relying on a minimum number of redundant subcarriers. This, together with subcarrier frequency hopping (FH), improves BER performance in the presence of freque...

In this paper, we investigate the performance of a downlink multiple-input multiple-output (MIMO) multi-carrier code division multiple access (MC-CDMA) system employing a receiver with iterative channel estimation (ICE). The MC-CDMA system transmits several data symbols per user and per orthogonal frequency division multiplexing (OFDM) symbol in parallel, with each data symbol being spread with...

Orthogonal frequency division multiplexing (OFDM) is a multi-carrier transmission technique, which divides the available spectrum into many subcarriers, each one being modulated by a low data rate stream[1]. Compare with the traditional ways, the OFDM system has the features of resisting frequency selective fading and high frequency-band utility ratio and so on. OFDM has been successfully appli...