Abstract
Relay strategies can increase coverage range and improve reliability for power-limited sensors. In this study, cooperative jamming schemes are investigated for security communications in two-hop multi-sensors relay networks where a passive eavesdropper can wiretap the relay channels in both hops. The normally inactive nodes can be used as cooperative jamming sources to confuse the eavesdropper. Artificial noise (AN) is maximised to degrade the signal-to-interference-plus-noise ratio (SINR) level at the eavesdropper, while satisfying the individual power constraint of each relay sensor and SINR constraint at the desired receiver. Assuming that CSI is perfect, relay beamforming weights can be obtained by solving a second-order cone programming problem. However, the available CSI is impossible to be perfect in practice. Therefore, a robust beamforming scheme is also presented. The transmit power used for AN is maximised, while satisfying the power constraint of each relay sensor and worst-case SINR constraint at the desired receiver under a bounded spherical region for the norm of the CSI error vector from the relays to the destination. Robust beamforming weight vector can be obtained by using S-procedure and rank relaxation techniques. The benefits of the proposed schemes are shown in simulation results.
Published Version
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