Eavesdropping-resilient wireless communication system based on modified OFDM/QAM air interface

Modern military communication systems are currently facing an important issue with the security. The rapid technological development provides us with the new advanced weaponry, including robots and unmanned vehicles, which rely on the communication system in background. Thus, it is important to provide the reliable and secure wireless communications channels, which are resilient to intrusions and data interceptions by enemies. In this paper, we propose a new approach for signal modulation based on the conventional orthogonal frequency division multiplexing and quadrature amplitude modulation. The novelty of this scheme is that only one signal component is physically transmitted through the channel, while other is added in the received according to the specific rules. Receiver adds the second component taking into account received signal amplitude, subcarrier index and data transmission mode. All possible combinations of these parameters are summarized in the mapping table, which is known only by transmitter and receiver. We propose multiple combinations of the proposed modulation scheme, which differs in terms of spectral efficiency, energy efficiency and security. Moreover, proposed approach provides opportunity to mix the signal within the large set of available subcarriers and create thousands possible options to confuse the eavesdropper. Simulations have been conducted to assess the performance of the proposed modulation waveforms over non-line-of-sight channels. Simulation results show that proposed quadrature amplitude modulation provides better performance in terms of bit error rate due to the absence of IQ-imbalance and phase noises in the modified waveforms.