MMSE based joint channel estimation for time division CDMA

In the TDD mode of UTRA (UMTS Terrestrial Radio Access) and IMT-2000 (International Mobile Telecommunications-2000) the multiple access scheme TD-CDMA (time division CDMA) is utilized. The combination of TD-CDMA with adaptive array processing in order to improve the data detection is presented and evaluated in many publications. Although multi-antenna receivers are considered in TD-CDMA, the conventional channel estimation technique which is state of the art in TD-CDMA does not take advantage of the directional inhomogeneity of the mobile radio channel. A minimum mean square error (MMSE) based joint channel estimation approach for TD-CDMA is presented, which allows consideration of the correlation properties of the desired and the undesired user signals in the space and time domains in order to improve the channel estimation and, subsequently, data detection. The achievable system performance improvements are illustrated by simulation results.