Anti-Jam Analysis of Frequency Hopping M-ary Frequency Shift Keying Communication Systems in High Frequency Rayleigh Fading Channels.

摘要

A certain type of M-ary Frequency Shift Keying (MFSK) communication systems, which use Frequency Hopping (FH) to combat jamming is studied in this work. In particular, the performance of such systems over High Frequency (HF) sky-wave channels, when subjected to intentional jamming, is the main topic of this study. The channels considered are characterized by Rayleigh fading and additive Gaussian noise. To combat jamming the communication system hops over the total spread spectrum bandwidth, which is many times larger than the 'instantaneous' bandwidth occupied by the MFSK signal. Located within the HF band and using sky-wave as the dominant propagation mode, the spread spectrum bandwidth is typically nonuniform, time dependent, and congested by many other users of the electromagnetic spectrum. In such an environment, Frequency Hopping FH mfsk systems seem to be more practical than 'Direct Sequence' spectrum spreading techniques. A FH/MFSK system can be easily programmed to use a noncontiguous band, thereby avoiding strong interfering signals that should not be interfered with.