Adaptive resource allocation for secure two-hop communication

Abstract

This paper develops novel transmission schemes to support secure dual-hop Alice-Ray-Bob relaying communication in the presence of a passive eavesdropper (Eve). Due to unknown eavesdropper channel conditions, data transmissions from Alice (to Ray) and from Ray (to Bob) are required to satisfy the secrecy constraint in terms of maximum acceptable secrecy outage probability (SOP). The throughput maximization problem is studied for two scenarios: 1) fixed (Alice and Ray) power allocation; and 2) adaptive power allocation. The resulting constrained optimization problems are solved using the Lagrangian approach. In each frame, either Alice or Ray or neither can be scheduled for transmission depending on the instantaneous main channel conditions. Numerical results demonstrate the effectiveness of the proposed schemes over the existing schemes under various secrecy constraint and signal-to-noise power ratio (SNR) regimes.