A novel finger assignment algorithm for RAKE receivers in CDMA systems

In CDMA systems, assignment of the RAKE fingers to the correct multipath components is crucial for the receiver to combat fading and to take advantage of the multipath diversity. This is particularly important since the number of fingers available is normally limited in order to maintain low receiver complexity. In this paper, we introduce a new RAKE receiver finger assignment algorithm (FAA) based on estimates of the signal-to-interference ratio (SIR) per path, as opposed to signal strength in the conventional schemes. We also introduce a simple algorithm to produce these SIR estimates. A performance comparison between the proposed scheme and the already existing schemes is presented. We show that the proposed scheme provides a significant performance improvement relative to that of the conventional schemes. For instance, the proposed scheme provides gains of up to 3.0 dB at bit error rate 10^-4, relative to the conventional scheme.