An OFDM-DCSK based Approach for D۲D Emergency Communications

In a critical situation such as a flood, storm, and earthquake, where the communication infrastructures have been seriously destroyed, Device to Device (D۲D) communications can be connected without the assistance of any operators. In addition, Equip the existing D۲D systems to provide high reliability, robustness, and other specific needs of the emergency services during the disasters seems to be unavoidable. In this paper, an Orthogonal Frequency Division Multiplexing based Differential Chaos Shift Keying system (OFDM-DCSK) based approach is presented to overcome the problems in emergency situations. An OFDM-DCSK receiver needs no channel estimation for data detection. Moreover, the combination of a blind power allocation scheme with a non-coherent receiver is very desirable because these techniques save power, without the need for communication infrastructure like Base Stations (BSs). On the other hand, the proposed system benefits from the additional advantages of DCSK-based systems such as reliability and robustness. We assign power coefficients to sub-carriers to guarantee a given level of outage probability.  To this aim, we calculate the outage probability for a power allocated OFDM-DCSK system using instantaneous signal-to-noise ratio expression. The power that guarantees a given level of outage probability can be calculated by a simple numerical algorithm. Simulation results validate the feasibility of the proposed scheme.