Because of the broadcasting nature of wireless communications, passive eavesdropping is a well-known security loophole. Generally there are two basic ideas to deal with the eavesdropper at physical layer: friendly jamming and channel state information dependent encoding. Based on the channel quantized physical-layer network coding (CQ-PNC), we propose a secured CQ-PNC scheme to combine both ideas aforementioned to prevent the eavesdropper from obtaining the messages.
Specifically, the CQ-PNC consists of co-channel signal superposition in the air (friendly jamming) and channel state information dependent mapping (PNC mapping). As a result, the information is more difficult to be detected at the eavesdropper, meanwhile there is almost no rate loss at the legal receiver. To verify the effectiveness of the proposed secure CQ-PNC, we implemented the scheme on a software defined radio (USRP) experimental platform.