Joint optimal power allocation and relay selection to establish secure transmission in uplink transmission of untrusted relays network

摘要

In this paper, the authors deal with secure transmission in two-hop amplify-and-forward network with untrusted relays. To prevent the untrusted relays from intercepting the source message and to achieve positive secrecy rate, the destination-based cooperative jamming technique is used. The authors propose joint secure best relay selection (BRS) and optimal power allocation (OPA) for uplink transmission of a cellular network when the base station is equipped with very large-scale antenna arrays. Then, the common performance metrics such as ergodic secrecy rate (ESR) and secrecy outage probability are evaluated for the optimised network. Moreover, the diversity order and diversity-multiplexing tradeoff of the system are examined. The authors obtain that the diversity order of joint BRS and OPA scenario is equal to number of relays. Finally, some numerical and simulation results are presented to validate the theoretical analysis and to show the advantages offered by the presented systems. They reveal interesting results that, by increasing number of untrusted relay nodes, the system performance improves. For example, for target ESR 2 bits/s/Hz and ten untrusted relay nodes, the optimised network saves about 5 dB for uplink transmission, in comparison with the system applying the BRS and equal power allocation.