Index Modulation Based Frequency Hopping: Anti-Jamming Design and Analysis

Reactive symbol-level jammer has attracted attention due to its low energy cost and high jamming efficiency. With the development of software-defined radio (SDR), the implementation of reactive symbol-level jamming has become more practical and efficient. To combat the reactive jammer, this paper proposes an index modulation based frequency hopping spread spectrum (IM-FHSS) scheme. Specifically, the current available frequencies are determined by multiple orthogonal frequency hopping (FH) patterns, and bit information is transmitted through the index of the active FH pattern. At the receiving side, we design an energy detector to distinguish the active and idle frequencies. With such implementation, IM-FHSS can obtain the improved resistance of reactive symbol-level jammer. Subsequently, we propose the alternative spectral efficiency (SE) mode of IM-FHSS in order to meet the high SE and low-power jamming scenarios. Furthermore, we analyze the BER of this scheme for the reactive symbol-level jamming under the cases of energy correlation, jamming rate, and phase offset. Theoretical analysis and simulation results show that IM-FHSS exhibits enhanced resistance to reactive symbol-level jamming than traditional FH scheme.