Digital coding by means of linear periodic time-varying filters

In modern telecommunications applications, the interest of linear periodic time-varying filters has been often demonstrated. They can be used for scrambling, multi-user access or channel modeling. Recently, the authors have shown that any linear periodic filter can be attractively realized by means of periodic clock changes. Nevertheless, all the solutions based on periodic clock changes correspond to analogue filtering cases that spread the spectrum. The original part of this paper consists of using periodic clock changes for binary signals with a non-spreading spectrum solution. We first recall the definition of linear periodic filters. In particular, it is shown that a stationary process subjected to such a filter becomes cyclostationary. The paper proposes then to use a periodic clock change on a binary signal as a coding. It is followed by a modulation that permits to obtain a spectrally efficient solution. We present the reconstruction method of the initial signal. An example illustrates a binary sequence transmission by means of a periodic clock change.