Generic MMSE Decision Directed Channel Estimation for OFDM and MC-CDMA

In this letter we propose a Minimum Mean Square Error (MMSE) Channel Impulse Response (CIR) estimator-aided Decision Directed Channel Estimation (DDCE) method, which is suitable for employment in both OFDM and MC-CDMA systems. Firstly, we outline the difficulty associated with the employment of the Least Squares (LS) approach to the problem of a posteriori Frequency Domain Channel Transfer Function (FDCTF) estimation in the context of a MC-CDMA system and derive a suitable MMSE-based CIR estimator, which circumvents the LS method’s deficiencies. Secondly, we demonstrate that the computational complexity associated with the conventional MMSE estimation method is relatively high compared to that of the LS method. Thus a reduced-complexity version of the MMSE estimator is proposed, which has a complexity similar to that exhibited by the LS-aided estimator. The MC-CDMA system using the reduced-complexity MMSE estimator proposed is shown to outperform the corresponding OFDM-based scheme.