Performance of Kalman equalization for the UMT FDD downlink in two-path fading channels

The performance of a discrete Kalman filter used as a chip-level channel equalizer in the downlink of the universal mobile telecommunication system (UMTS) with frequency-division duplex (FDD-UMTS) is analyzed in terms of chip estimation error and bit-error probability. The dependence of the chip estimation error on the signal-to-noise ratio, the transmission channel characteristics, and the filter length is derived and discussed for a two-path frequency-selective static channel. It is shown by simulation that the result for the chip error is also valid for two-path frequency-selective fading channels. A semianalytical approach is utilized to derive the bit-error probability of the Kalman equalizer, and the expression is verified by simulations in a fast-fading FDD-UMTS environment.