Boumediene Lasri

Multi-carrier Cdma over Multi-path Fading Channel Boumediene Lasri

Multi-Carrier (MC) modulation has recently evolved as an efficient modulation technique which can provide similar frequency diversity in the system. It is basically derived from orthogonal frequency division multiplexing (OFDM). Due to the dispersive nature of the mobile communications channels, MultiCarrier Code Division Multiple Access (MC-CDMA) signals will be affected by Inter channel interference (ICI), Inter symbol interference (ISI) and Multiple Access Interference (MAI). The precedent problems lead to the loss of subcarrier orthogonality. To solve the interference problem, a cyclic extension was introduced to the transmitted symbols, but its introduction results into spectral efficiency loss. Firstly, we use the Frequency-Time MMSE equalizer (FTE) to regain the corresponding loss in performance. Secondly, we derive the Multicarrier Equalization by Restoration of redundancy (MERRY) algorithm blind. We can use the adaptive channel shortening algorithm for updating a Time-domain Equalizer (TEQ) in a system employing MC-CDMA modulation. We show that the MERRY algorithm employee to the MC-CDMA system converges considerably more rapidly than has that to apply for (OFDM) system.