Influence of channel estimation on the performance of a coherent DS-CDMA system

Direct-sequence code division multiple access (DS-CDMA) has become one of the favourite candidates for future mobile radio communication systems. The uplink of a coherent DS-CDMA system is investigated. The channel estimation is carried out via a control channel, which is transmitted simultaneously to the data channel. This concept is very closely related to the CODIT-CDMA concept. In the channel estimation, an averaging process is involved, which for long averaging periods, suppresses the noise influence efficiently. On the other hand, long averaging intervals lead to systematic errors in the estimated channel coefficients due to the time-variant behavior of the channel. Taking into account these effects, a closed-form analysis of the data-channel symbol-error rate (SER) is presented. This analysis allows the prediction of the system's performance and helps to optimize the parameter settings for channel estimation.