Multicarrier code division multiple access (MC-CDMA), is a promising multiplexing technique for future communication systems. In this study, we employ the well-known Walsh-Hadamard spreading codes for synchronous downlink transmission of MC-CDMA systems. The spreading codes allow that the frequency diversity to be efficiently exploited. However, multipath propagation may cause orthogonality among users is distorted, and this distortion produces multiple access interference (MAI). To eliminate this effect, we propose a pre-filtering-based MC-CDMA system which uses a pre-filtering technique at the transmitter and an equal gain combining (EGC) scheme at the receivers, respectively. Our proposed prefiltering technique transforms the transmitted signals so that the MAI can be eliminated, and the EGC scheme weights the signals received from all subcarriers so that channel distortions can be compensated. Furthermore, the proposed technique can calculate the transmitted power over all subcarriers to satisfy the required quality of service of each user and archive MAI-free. In this paper, performance in terms of bit error rate is analyzed; in comparison with the EGC, orthogonal restoring combining, and maximal ratio combining schemes at receiver, respectively.Recently, the demand for wireless communication services has expanded to encompass new applications. Now, wireless communication service includes not only traditional services, such as e-mail, ftp, and web applications, but also multimedia services, such as audio, video, and images. Therefore, the ability to provide users with a high data transmission rate is becoming increasingly important in wireless communication systems. The multicarrier code division multiple access (MC-CDMA), also known as OFDM-CDMA [1,2], is an attractive technique for achieving high data rate wireless data transmission in frequency-selective fading channels. While transferring data, the MC-CDMA system splits a high-rate data stream into several lowrate data streams, and duplicates each of these low-rate streams into multi-copies; each of these low-rate streams are multiplied by a specific spreading code. Because a transmission signal is spread in a frequency domain, the MC-CDMA system can efficiently make use of frequency diversity techniques to improve the system performance. The techniques have been shown to counteract the effect of multipath propagation. Several researchers have studied the exact performance of the bit error rate (BER) of MC-CDMA systems over a multipath channel [3--5]. Generally, MC-CDMA signals transmitted over a fading channel will be influenced by delay spread which leads to multiple access interference (MAI) for which the orthogonality of the spreading code among users is distorted [6].MAI is the major interference that limits the performance of CDMA-based systems [3--5]. To mitigate MAI, signal detection techniques for MC-CDMA systems are discussed and compared in Ref. [1]. Several researchers have studied multiuser detection (MUD) techniques [1,7--10] for MC-CDMA sy...