Distributed Carrier Waveform With Joint Equalization for Covert Links

The patent divides the single-carrier base waveform into multiple frequency strips and redistributes them across multiple subcarriers in a pseudo-random order. This segmentation allows the signal to achieve LPI/LPD characteristics through distributed spectral presence while maintaining high data rates by utilizing the aggregate bandwidth of multiple subcarriers rather than requiring excessive bandwidth from traditional spreading techniques.

The patent employs asymmetric pseudo-random redistribution of frequency strips across subcarriers, creating an irregular spectral pattern that lacks the repeating sequences characteristic of traditional spread spectrum signals. This asymmetry prevents blind cyclostationary and spectral analysis detection methods from identifying periodic structures, while the pseudo-random nature maintains security against eavesdropping.

The patent transitions from single-carrier modulation to multi-carrier distributed modulation, adding a dimensional aspect of frequency distribution. By spreading data across multiple subcarriers with pseudo-randomly assigned frequency strips, the system achieves high data rates through the combined capacity of multiple carriers rather than relying solely on high-order modulation of a single carrier, thereby maintaining spectral energy density while increasing throughput.

The patent assigns different pseudo-random patterns and frequency strip distributions to different subcarriers, creating local variations in spectral characteristics. This local quality differentiation means that even if an adversary intercepts the signal with geographical advantage, the distributed and varied spectral presence across subcarriers makes it difficult to detect and reconstruct the original waveform, as each subcarrier contains only a fragment of the overall signal structure.