A reduced complexity partial sampling MMSE receiver for asynchronous MC-CDMA systems

In multi-carrier CDMA (MC-CDMA) system, timing of the starting point of the desired signal must be estimated to demodulate the desired signal. Especially for asynchronous MC-CDMA systems, rather a complicated timing estimation is needed, due to the random delays of all users. Zong, Wang and Bar-Ness (see VTC2001)proposed a partial sampling MMSE (PS-MMSE) receiver which does not require timing estimation. However, it requires several times more filter´s taps than the conventional MC-CDMA receiver. The number of taps is a multiple of, and depends on, the number of subcarriers (i.e., the processing gain). A reduced complexity partial sampling MMSE (RPS-MMSE) receiver is proposed, which can be adaptively implemented by using the least-mean-square (LMS) algorithm. The proposed structure allows one to choose the number of taps independent of the number of subcarriers, hence having more flexibility in choosing the number of taps than with PS-MMSE receiver. With this structure, we can use fewer taps than with the PS-MMSE receiver and still can obtain comparable performance