Physical Layer Security with Spatial Modulation: Current Advances and Future Directions

摘要

Spatial modulation (SM) and its power to address physical layer security (PLS) issues have been under vibrant investigation. In this paper, we present an overview of PLS with SM in a methodological manner. The advantages and drawbacks of these techniques are specified. Next, we propose a cost- and energy-efficient secure SM scheme based on the concepts of the reconfigurable antenna (RA) and multiplicative noise. Specifically, the transmitter is equipped with a single RA and the receiver has multiple conventional antennas. In each transmission, one symbol duration is equally divided into multiple sub-symbol periods. During each sub-symbol period, a specific radiation pattern is activated and a weighted sub-symbol is sent through the RA. The receiver sums up the received signals in all sub-symbol periods to demodulate the information. The weighting coefficients are properly designed such that the summed received signals have a single non-zero element, of which the position delivers additional spatial information. In addition, the weighting coefficients serve as a source of multiplicative interference to unintended eavesdroppers. The proposed scheme does not require knowledge of the wiretap channel and, in contrast to conventional jamming-aided schemes, all transmit power is saved for useful signals. Finally, several prospective directions are identified for future research along the line of PLS-SM.