Index-Modulation Embedded Mode Hopping for Antijamming

The emerging orbital angular momentum (OAM), which is a property describing the helical phase fronts of electromagnetic waves, offers the potential to improve reliability and increase the SE in wireless communications. To achieve efficient antijamming and increase the SE of wireless communications with slight computational complexity cost, in this article, we propose an index-modulation embedded mode-hopping (IM-MH) scheme, which simultaneously activates several OAM modes for hopping along with additional index information and signal information transmission. We analyze the average bit error rates (ABERs) for our proposed IM-MH scheme with perfect channel state information (CSI) and imperfect CSI, respectively. We also propose the index-modulation embedded double-serial MH (IM-DSMH) scheme, which randomly activates one OAM mode as the serial second hop to transmit the hopping signals in the IM-MH scheme, to further decrease the ABER of wireless communications. Extensive numerical results demonstrate that our proposed schemes within a narrowband can achieve the low ABER and significantly increase the SE. Also, the ABERs of our proposed IM-MH and IM-DSMH schemes are around 25% and 10%, respectively, compared with that of the mode hopping scheme.