SNR thresholds to meet a given error rate with practical cooperative relaying

Compared to direct transmission, cooperative relaying can substantially decrease the receiver's Signal-to-Noise Ratio (SNR) threshold to reach a given error rate. These SNR gains can be utilized to improve the error rate, energy consumption, or spectral efficiency of a wireless network. Focusing on practical half-duplex relaying, we derive the outage probability for a simple combining scheme, called Frame Selection (FS). We show that FS experiences only a minor performance drop compared to Maximum Ratio Combining (MRC) but makes cooperation easy to implement at the link layer. In addition, we provide numerical examples of SNR thresholds that can immediately be applied to choose the transmit power and rate in IEEE 802.15-based cooperative Wireless Sensor Networks (WSNs).