A frame synchronization scheme for uplink MC-CDMA

Most present synchronization techniques for downlink MC-CDMA (multi-carrier code division multiple access) are not suitable for uplink MC-CDMA because users' signals reach the base station asynchronously. In this paper, a frame synchronization scheme for uplink MC-CDMA with asynchronous transmission is suggested. This technique uses a time domain signal which is produced when the spreading code of MC-CDMA is given in the frequency domain. The correlation of already known information, that is, IDFT of the spreading code and sampled received signal, becomes the metric of frame synchronization. In order to obtain good correlation characteristics in the time domain, a new spreading code scheme is suggested. The proposed scheme uses no other information than already known spreading code and does not need FFT operation. Also, the scheme performs well in multipath fading channels.