Space time block code for cdma2000 with pilot channel estimation

The space time block code (STBC) has attracted much attention for its ability to achieve significant diversity gain. And most of the papers related to the STBC have discussed in its applications to the wideband code division multiple access (W-CDMA) system. Only a few papers have studied its application to cdma2000 system. The paper in Wu et al. (2001) is one of them. Each user in a forward link employs a STBC encoder and the number of the STBC encoders is equal to the number of users, and the channel estimation is not discussed in Wu et al. However, this paper employs only one STBC encoder for the multiple users at a base station, and provides a practical channel estimation scheme using the STBC and the pilot channel in cdma2000 together. For the sake of simplicity, we consider two transmit antennas and one receive antenna. No error correction coding is employed. Also Jakes´ model is employed for the Rayleigh fading channel simulation. Multiple access interference is modeled as additive white Gaussian noise (AWGN). A RAKE receiver of three fingers is employed for three unequal strength multipaths, based on ITU-R M.1225. The simulation results show that the STBC can improve bit error rate (BER) significantly. For example, the STBC with the channel estimation can make improvement of 4 dB in signal-to-noise ratio at BER=10^-2, compared to the one transmit antenna system without STBC.