Soft Handover Overhead Reduction by RAKE Reception with Finger Replacement

Abstract

We propose and analyze a new finger replacement technique that is applicable for RAKE receivers when they operate in the soft handover (SHO) region. In the SHO region, the receiver uses by default the strongest paths from the serving base station (BS) and only when the combined signal-to-noise ratio falls below a certain pre-determined threshold, the receiver uses more resolvable paths from the target BS to improve the performance. Instead of changing the configuration for all fingers, the receiver just compares the sum of the weakest paths from the serving BS with that of other paths from the target BS and select the better group. Applying some recent results on order statistics, we attack the statistics of two partial sums of order statistics and provide an analytical framework for the performance evaluation of the proposed scheme. By investigating the tradeoff between the error performance and the SHO overhead, we show through numerical examples that the new scheme can save some SHO overhead load.