A family of wavelet-related sequences as a basis for an LPI/D communications system prototype

Waveform and Transceiver Designs for Smart Radio

“…Interestingly, comparisons with QPSK reveal a noticeable improvement in non-detectability using fourth power law detectors. Another paper with similar content [51] is authored by the same team and so will not be expounded upon here. It is worthwhile to note, however that in this paper an actual hardware testbed for demonstrating and implementing the LPI/D nature of this method is discussed.…”

“…However, a trade-off with frequency localization spreading due to increased filter bank decomposition keeps this performance increase within practical limits. 51 …”

Orthogonal transmultiplexers in communication: a review

“…Second, a DFT-based DMT modulation scheme has become the standard for asymmetric digital subscriber line (ADSL) communications, which provide an efficient solution to the last mile problem (e.g., providing high-speed connectivity to subscribers over the unshielded twisted pair (UTP) copper cables) [21], [22], [24], [25]. In addition to these two successful applications of multicarrier modulation, we also highlight several emerging application areas, including spread spectrum orthogonal transmultiplexers for CDMA [15] and low probability of intercept (LPI) communications [48], [49] (which might further benefit from the discussions presented). The time-frequency and orthogonality properties of function sets, or filter banks, are the unifying theme of the topics presented in the paper.…”

“…A dynamic or timevarying orthogonal signature-generation procedure is a critical component of LPI communication systems. Therefore, several hopping techniques (e.g., frequency hopping, time hopping, frequency and time hopping) along with the pseudo-random direct sequence (DS) structures are widely used in practical systems [32], [48], [49].…”

“…The block transforms like Walsh-Hadamard and DFT bases have been widely used for LPI communications. More recently, subband transforms have been forwarded for this application due to their flexible time-frequency properties [48], [49]. We expect more studies in this application area in the near future, including their extensions for commercial communication scenarios.…”