Distributed STBC With Soft Information Relay Based on Gaussian Approximation

We consider a system where the source transmits signals to the destination via two-relays where distributed space time block codes (STBC) are used. It is assumed that the signals are coded at the source and decoded at the relays. In the general case, the decoding at relays might not be perfect and hence the soft information is forwarded. Considering the independent Rayleigh channels and using the Gaussian approximation of the soft information, we theoretically derive the system Bit Error Rate (BER) performance at the destination with the space-time decoding. This result permits the numerical performance evaluation and may have other potential applications such as the power allocation between the relays.