| In the past few years, cellular phones have been penetrating into our society at an explosive growth rate. For more than a decade, research has been constantly conducted to find a technology allowing the introduction of multimedia capabilities into mobile communications. One of the most critical aspects in the transmission line is the radio interface and more particularly, the multiple access procedure. The channel for mobile communications is a particularly hostile transmission environment, simultaneously containing multipaths, noise and interference that make the transmission of high bit-rates difficult.;To overcome these shortcomings, a hybrid technique between OFDM (Orthogonal Frequency Division Multiplexing) and CDMA (Code Division Multiple Access) is suggested in this paper. The system is called MC-DS-CDMA (Multicarrier Direct Sequence CDMA) and it consists of a multicarrier signaling technique applied to a direct-sequence CDMA system. This type of signaling has the desirable properties of exhibiting an inter-symbol interference suppression effect, along with robustness to fading. It does not require the use of neither an explicit Rake structure nor an interference suppression filter. Moreover, the spectral efficiency is doubled compared to the one of the DS-CDMA techniques thanks to the overlapping carrier spectra. (Abstract shortened by UMI.). |
