Multihop Decode-and-Forward Relay Networks: Secrecy Analysis and Relay Position Optimization

Relay communication has advantages over direct transmission in terms of secrecy capacity. In this paper, the performance of secrecy, offered by multihop decode-and-forward relaying, is investigated and compared to its counterpart in direct transmission. Three key performance measures are derived over Rayleigh fading channels: probability of non-zero secrecy capacity, secure outage probability and secrecy capacity, which are valid for an arbitrary number of hops. Based on the tractable form of the probability of non-zero secrecy capacity, the optimization problem of trusty relay replacement is also studied. Numerical results indicate that a proper relay replacement can increase the network security without extra network resources. The correctness of analytical results is confirmed by using a MATLAB-based independent simulation model. Keywords– Secrecy capacity, decode-and-forward, multihop networks, probability of non-zero secrecy capacity, secure outage probability. This work was supported under Project 39/2012/HÐ/NÐT granted by the Ministry of Science and Technology of Vietnam.