One transmission scheme based on variable MSK modulator for wireless physical layer security

In this paper, we study the generating methods of MSK (minimum-shift keying) signal and present 8 types of MSK modulator structures. Results show that the MSK modulator structure has the certain waveform encryption function for the input messages. Base on this discovery and the idea of frequency-hopping communication, we propose a physical layer transmission scheme with MSK modulation, where the MSK modulator structure can be changed according to a secret between the source and the destination. Through theoretical analysis and experimental simulation, we show that the BER (bit error rate) as high as about 50% makes demodulating practically infeasible for the eavesdropper in the proposed scheme, thus securing the communication between the source and the destination. Furthermore, this security transmission scheme is independent on the channel variations of the wireless environment, and is very suitable for the wireless networks where the channel remains static for most of the network lifetime.