Channel estimation methods adequate to space time transmit diversity receiver in the W-CDMA IMT-2000 system

This paper presents some channel estimation methods adequate to the space time transmit diversity (STTD) receiver that coherently demodulates signals from each path of two transmit antennas. The STTD mode receiver estimates the channel information of each antenna path from the received common pilot channel (CPICH) signals with known orthogonal patterns transmitted by two antennas of the base station. The conventional channel estimation methods using pilot filter result in serious Inter-antenna interference caused by Imperfect orthogonal processing of signals between the two antennas. Another drawback Is the Inter-symbol interference caused by lack of orthogonality between two symbols which is the basic premise of STTD decoding algorithm. This paper analyzes the effects of the inter-symbol interferences and proposes some robust channel estimation methods to reduce the effects of the inter-symbol interference. This paper also compares the performance of the proposed channel estimation methods in various fading channel environments through the effective signal to interference ratio (SIR) and the bit error rate (BER).