Evolution of Interplex Scheme with Variable Signal Constellation

Abstract

In this paper we present a modification of a multiplexing scheme for DS-CDMA signals, known as interplex scheme. The interplex allows to map several binary DS-CDMA signals onto a constant envelope signal, resulting in a signal that can be efficiently amplified. In order to obtain a constant envelope constellation, some additional power is transmitted that is not used for data transmission. This so called inter-modulation (IM) power can be too much compared to the useful power or the High Power Amplifier (HPA) non-linearities are not so severe to demand a perfectly constant envelope signal. The basic idea of this work is to adapt the interplex signal to the HPA at hand.