Security Transmission in MIMO Ubiquitous Power Internet of Things Systems

Power line communication (PLC) is a promising technique because of its wide distribution and low cost. However, due to the feature of PLC channel, the communication quality is unsatisfactory and there exists security risks. In this paper, we design a frequency division (FD) multiple-input and multiple-output (MIMO) PLC system. Firstly, since power line channels have frequency selectivity problems, it is necessary to select an appropriate frequency band for communication, so we adopt digital front-end (DFE) in the PLC system. The DFE is used to adjust the frequency and bandwidth configuration of the carrier signal. In order to determine the optimal frequency point for upstream and downstream communication, a sweep mechanism under the FD PLC system is designed. The analysis of the sweeping mechanism finds that the sweeping overhead only requires
2N
+1 communications, which greatly improves the sweeping efficiency. Secondly, we find this frequency division technology can also be used to enhance the security of MIMO PLC. The real signal can be hidden in the frequency domain and obfuscated in the time domain by using DFEs to adjust the frequency and bandwidth information of the real signal and artificial interference noise. Simulation indicates that the proposed method can guarantee the correct reception and demodulation at the legitimate receiving user end, while the BER at the eavesdropping user end fluctuates around 0.5, thus cannot correctly demodulate the real signal.