In this paper we introduce a new class of communications systems called wavelet transform domain (WTD) systems. WTD systems are transmultiplexer (TMUX) structures in which information to be communicated over a channel is encoded, via an inverse discrete wavelet transform (IDWT), as the wavelet coefficients of the transmitted signal, and extracted at the receiver by a discrete wavelet transform (DWT). WTD constructs can be used for covert, or low probability of intercept/detection (LPI/D) communications, baseband bandwidth efficient communications, or code-division multiple access (CDMA). This paper concentrates on the spread spectrum applications.
Richard S. Orr,
Michael J. Lyall,
"Wavelet transform domain communication systems", Proc. SPIE 2491, Wavelet Applications II, (6 April 1995); doi: 10.1117/12.205394; https://doi.org/10.1117/12.205394