This paper proposes probability-based rake receiver (PRR) as a new concept of error concealment in ultra-wideband multiple access systems in the presence of frequency-selective fading according to the COST*207 channel model. To form a beam pattern, after despreading with specified user code and signal integrating by a bank of integrator, signal weights are calculated based on signal strength at each finger of rake receiver. Afterward, the matched signals are summed up with maximal-ratio combining and are passed through frame decision unit (FDU), which requires additionally a priori information in terms of estimated bit error probabilities. In fact, we exploit a practical rake combining scheme and probabilitybased error degradation technique before any decoding applications. Monte Carlo simulations have been used to evaluate the receiver bit-error rate performance in frequencyselective mobile radio channel environments.