The Generalized Secretary Problem Algorithm for Secrecy-Achieving Relay Selection: A Good Complexity-Security Trade-off?

Abstract

In this work, a low-complexity generalized secretary problem (GSP) algorithm-based multi-relay selection scheme is proposed for enhancing the secrecy level of delay-sensitive communications. In detail, a number (i.e., K) of relays are suboptimally selected among a total of N ones in a dual-hop multi-relay wireless communication system to perform cooperative diversity. The signals reaching the destination from such selected relays are combined through the maximal-ratio combining technique under the presence of multiple eavesdroppers aiming to intercept the signals broadcasted by the selected relays. A novel analytical framework is derived, illustrating the probability of optimal selection using the proposed GSP-based approach. Then, the GSP’s algorithm performance in terms of security and complexity is evaluated and compared against the well-known optimal generalized selection combining scheme.