The BEP of incremental cooperative OSTBC MIMO systems using decode and forward protocol

The main aim of wireless network designer is to minimize the wasting of channel resources. In regular cooperative Decode-and-Forward (DF) systems, relays forward source signals to the destination regardless of channel conditions which constitute a significant loss in radio resources. To overcome this drawback, incremental relaying was proposed in which the destination decides after receiving a source signal to decode it or to request the help of a relay. In this paper, we analyze the performances of an incremental Multiple Input Multiple Output (MIMO) DF relaying based on an Orthogonal Space Time Block Code (OSTBC) where all transmissions are done over independent identically distributed Rayleigh fading channels. We derive closed-form expressions of the Bit Error Probability (BEP) at the destination. We provide a study on the effect of the signal to noise ratio (SNR) threshold and the relay´s positions on the system performances. The obtained results show that an incremental cooperative MIMO system offers better performances compared with an incremental cooperative SISO one.