Physical Layer Network Coding with Multiple Untrusted Relays for Physical Layer Security

We proposed the physical layer security (PLS) under the untrusted relay in the wireless communication with the physical layer network coding (PLNC). In PLNC, the two information source accesses the relay station, simultaneously and thus it is difficult for the relay station to demodulate each signal due to the masking-effect from the other signal. As a result, the leakage of information to the untrusted relay is avoidable. The transmit power control (TPC) for the balancing between the two received signal powers is powerful. The secure capacity is enlarged but has not been optimized for maximizing the secure capacity. In this paper, the quasi-optimization of TPC for enlarging secure capacity is derived in the wireless communication with the untrusted relay and PLNC.