A novel channel identification method for downlink multicarrier CDMA systems

This paper presents a new blind channel identification method for downlink multicarrier CDMA (MC-CDMA) systems. This technique uses subspace decomposition for channel identification and exploits the orthogonality property between the noise subspace and the received user codes to obtain a channel identification algorithm. It is shown that in order to increase the number of simultaneous users, and to still have a good estimation of the channel, a modification of the MC-CDMA system has to be considered by using codes larger than the spreading gain. The performance of this algorithm is analyzed by deriving a theoretical expression of the mean square error (MSE) estimation. This expression is compared with numerical results of some computer simulations to illustrate the validity of the analysis. The paper also introduces a linear detector for this environment.