The Degradation of Cooperative Jamming Suppression for Frequency Mismatch in FH Secure Systems

In the communication systems employing cooperative jamming (CJ), frequency mismatch will degrade its jamming suppression performance. This paper aims to investigate the suppression performance degradation of the CJ sheltered frequency hopping (FH) systems under unknown frequency mismatch. First, the system transceiver architecture is detailed illustrated. Then, the residual CJ after suppression is mathematically depicted, and the closed-form expression for the CJ suppression ratio (CJSR) is provided. Finally, the expectation and cumulative distribution function (CDF) of CJSR are derived to measure the degradation of suppression performance for unknown frequency mismatch. Theoretical and simulation results confirm that frequency mismatch in actual FH systems will degrade its CJ suppression performance, and this degradation will get worse for longer hop length or larger CJ power, which guides the actual transceiver design.