A Robust Ratio-Threshold Technique to Mitigate Tone and Partial Band Jamming in Coded Frequency Hopped Communication Links

摘要

Frequency hopping has long been regarded as an effective technique to thwart intentional and unintentional interference. The latter includes also fading and multipath. An advantage of frequency hopping, as compared to direct sequence spread spectrum techniques, is that phase coherence is not required. This makes frequency hopped systems more robust, since they are dependent on one less parameter, which is particularly significant for fading channels wherein rapid phase variations make it difficult if not impossible to track. On the negative side, noncoherent systems performance is inferior to coherent systems, particularly when the number of bits per hop is small (or worse yet, fractional). More serious is the fact that tone or partial band jammers can cause severe degradations (of orders of magnitude) relative to full band Gaussian jammers.