Secure Connectivity Using Randomize-and-Forward Strategy in Cooperative Wireless Networks

In this letter, we study the problem of secure connectivity for colluding eavesdropper using randomize-and-forward (RF) strategy in cooperative wireless networks, where the distribution of the eavesdroppers is a homogenous Poisson point process (PPP). Considering the case of fixed relay, the exact expression for the secure connectivity probability is obtained. Then we obtain the lower bound and find that the lower bound gives accurate approximation of the exact secure connectivity probability when the eavesdropper density is small. Based on the lower bound expression, we obtain the optimal area of relay location and the approximate farthest secure distance between the source and destination for a given secure connectivity probability in the small eavesdropper density regime. Furthermore, we extend the model of fixed relay to random relay, and get the lower bound expression for the secure connectivity probability.