D2D discovery approach based on spreading technique for public safety

Geological processes such tornados, avalanches or earthquakes can unleash adverse effects especially life losses, when we miss detect the presence of victims in devastated area. Statistics prove that death toll caused by natural hazards is becoming more prevalent from year to another. Meanwhile, telecommunications are booming with arising broadband networks. Besides, new wireless applications lead to the necessity of emerging a new communication fashion, especially in sensitive situation like public safety. Device to Device (D2D) communication, is one of promising alternative to circumvent public safety and to enhance emergency communications capabilities. The non assisted peer discovery concept over LTE raises some significant challenges so that in this paper, we propose a new approach that relies on spreading technique using orthogonal codes. Every victim signal will be spreaded by a code drawn from an orthogonal matrix called Hadamard matrix. Doing so, we improve the probability of successful detection of victims while keeping very low the probability of False Alarm thanks to the strengthening of signal by the spread process. The reliability of our proposal scheme is underlying by numerical simulations. Detection decision considers a correlation coefficient between the amount of received signal and the expected one spreaded to every orthogonal code. The coefficient is compared to a threshold in order to conclude a peer presence.