Physical Layer Security for Cooperative Multihop Routing in Wireless Networks

Physical layer (PHY) security that is based on information-theoretic secrecy has recently emerged as an alternative option for traditional cryptographic techniques to secure wireless networks. In this paper, we study the problems related to routing scheme along with PHY security for a multihop wireless network so that full diversity can be achieved at each hop. We propose a hop-by-hop best relay selection for the multihop ad-hoc wireless network consisting several relays at each hop in presence of an eavesdropper such that a secure routing scheme to transmit a confidential message from transmitter to legitimate receiver is achieved. The selection is performed considering the instantaneous channel conditions of relay as well as eavesdropper at each hop. We derive a closed form expressions for the probability of non-zero secrecy capacity along with end to end probability of secrecy outage at a normalized secrecy rate. Moreover, we provide an asymptotic expression to gain insights on the diversity gain.