Channel estimation filter using time-multiplexed pilot channel for coherent RAKE combining in DS-CDMA mobile radio

An improved, pilot symbol-assisted channel estimation filter, called the weighted multi-slot averaging (WMSA)channel estimation filter, is presented for DS-CDMA transmission links using coherent RAKE combining. Known pilot symbols are periodically time-multiplexed with the sequence of transmitted data symbols; they are placed at the beginning of each data slot. The WMSA channel estimation filter extends the observation interval over several slots. The. average bit error rate (BER) performance achievable with coherent RAKE combining using the proposed WMSA channel estimation filter is evaluated by computer simulations in a frequency selective multipath Rayleigh fading channel and the results are compared with those achievable with the use of other channel estimation filters such as an interpolation filter. The DS-CDMA reverse link requires fast transmit power control(TPC). In this paper, we also consider fast TPC based on the measurement of signal-to-interference plus background noise ratio(SIR). The average BER performance with the time-multiplexed pilot channel is also compared with that with the parallel pilot channel.