Decouple-and-Forward Relaying for Dual-Hop Alamouti Transmissions

In this letter, decouple-and-forward (DCF) relaying for dual-hop Alamouti transmissions is proposed as enhanced amplify-and-forward (AF) relaying to achieve spatial diversity gain especially provided by a two-antenna relay. DCF relaying that consists of decoupling, re-encoding and amplifying needs a little more complicated relay than AF relaying but a less complicated one than decode-and-forward (DF) relaying. Assuming uncorrelated Rayleigh fading channels, we derive a probability density function (PDF) of end-to-end signal-to-noise ratio (SNR) for the DCF system and provide its bit error rate (BER) performance. Numerical investigation shows that the analysis provided in this letter is exact and in dual-hop Alamouti transmissions, DCF achieves BER close to DF and even better BER when SNR is low.