Multiplex modulation techniques for a navigation constellation simulator

Nowadays, GNSS signals offer different services on the same signal frequency band. This requires for at least three components to be multiplexed to the same signal. The system designer is facing the challenge to combine multiple signal components to achieve a constant envelope composite signal with the highest combination efficiency. Several equivalent mathematical descriptions of this signal type are known. In addition, there are various algorithms to find the optimal solution related to the minimization of the undesired inter-modulation products. The objective of this paper is to analyze different mathematical representations of the multiplex scheme and identify the most suitable one. The goal is to find a hardware efficient solution which can handle all current state-of-art and future multiplexing schemes. The latter part is fundamental to implement it in a Navigation Constellation Simulator with the aim to support all existing and future GNSS signals with this multiplex schema. The evaluation of the optimal multiplex schemes is an ongoing process and it is probable that the solution is based on numerical simulations. A simulator can contribute to the verification process in regards to non ideal signals.