Performance of Simplified Receiver Diversity Schemes in 3G Systems

The paper describes a few simple solutions for a two-antenna receiver diversity combining scheme applied to the mobile terminal of a WCDMA cellular system. All schemes assume that combination takes place right after the low noise amplifiers following the receiving antennas, thus avoiding the need for duplication of the receiver chain. Combining strategies include optimal combining, suboptimal combining and selection combining, in addition to a new, very simple scheme exploiting the turbo code diversity. Different schemes are compared by simulating them in a very realistic 3GPP scenario, with a receiver including Rake, turbo decoder and channel estimation. To check the obtained performance with information-theoretical limits, a mixed analytical-simulation technique is used to evaluate bounds to the outage probability. The paper also addresses the problem of the feedback control algorithms that govern the RF combination through some suitable baseband signal processing.