INFLUENCE OF CHANNEL ESTIMATION ON THE PERFORMANCE OF A COHERENT DS-CDMA SYSTEM

In this paper, the uplink of a coherent direct-sequence code division multiple access (DS-CDMA) system will be investigated. The channel est imation is tarried out via a control channel, which is transmitted sim ultaneously to the data channel, This concept is very closely related to the CODIT-CDMA concept, In the channel estimation, an averaging pro cess is involved, which for long averaging periods, suppresses the noi se influence efficiently. On the other hand, long averaging intervals Lead to systematic errors in the estimated channel coefficients due to tile 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 predicting the system's perfo rmance and helps to optimize the parameter settings for the channel es timation.