The present paper deals with indoor positioning based on a technique combining the characteristics of two systems: pseudolites and repeaters. This solution tries to combine the best of each method: for pseudolites, the ability to cope with carrier phase measurements to improve the accuracy and reduce the effect of multipath, and for repeater the simplicity of the infrastructure and the automatic synchronisation with the satellite constellation. A pseudolite is a long established and relatively well-known concept: it consists of ground based stations broadcasting GNSS-like signals. A receiver based on the ground can process this signal exactly as if it was a satellite signal and use it as satellite data in the computation of a navigation solution. Thus it is possible to deploy a ground based constellation of “pseudo-satellites” in order to compute a position inside buildings or any places where GNSS signals are too weak to be processed by classical or highly sensitive GNSS receivers. Since the signal has the same structure as the outdoor signal, precise measurements can be carried out like carrier phase measurements allowing the multipath error to be mitigated. However, there are limitations to this method. First is the synchronisation of the ground based constellation. As in any GNSS system, synchronisation is vital and it can be very expensive to have a stable clock on each pseudolite. Second is the potentiality of high interference between the pseudolites. As the distances of propagation are relatively small and the indoor environment has a propensity to raise obstacles in the signal trajectory, the difference of power between two signals can be high enough to lead to the disruption of the weakest by the strongest. (There is also potential interference with the GNSS signals but it does not concern the present discussion.) This phenomenon is called the Near-far problem. Thus, pseudolites are interesting but limited by the synchronisation and the Near-far problem. The repeater based technique has several declinations as shown in the section II.B of the paper, but the main principle remains. It consists of collecting GPS signals from an outdoor antenna and then forwarding them indoors in a sequential switching mode without any further treatment other than amplification. Each repeater, which consists of an antenna and a cable linked to the sequential switcher, transmits signals over a specific period while the others are switched off. Signal switching induces an offset of phase on the signal received by an indoor receiver. This offset corresponds to the difference of time of arrival between two successive repeaters. Four such Time of Difference Of Arrival measurements are then necessary to compute a position. With such a method, there is no interference between repeaters, thus no longer a Near-far problem. In addition, there is no need for expensive synchronisation of the constellation, but the switching induces signal discontinuities that limit the possibility of carrier phase measurements. Consequently, it increases the influence of multipaths on the computed solution. The proposed method, called the Repealite method, consists of transmitting a repeated signal as for the repeaters. But, instead of switching, the transmission on each antenna is delayed in such a way that the codes (Which are the same, though delayed, for all satellite signals received.) transmitted on each repealite do not interfere once they arrive at the receiver antenna. The principles of this method were presented in [1] and [2]. It is clear that the continuity of the signal allows carrier phase measurements and it is also clear that no synchronisation is required. However, the Near-far problem remains and can even be worse than in the case of pseudolites. The point we want to focus on this paper is the high level of interference than can occur because of simultaneous broadcasting of different satellite signals. This can induce severe interference that can disrupt the signal. This paper mainly focuses on methods developed in order to improve correlation mitigating the effect of the interference between repealites, interference that we call systemic interference. After the state of art of the GNSS based indoor positioning techniques in section II, the principles of the Repealite method are presented in section III which ends with a theoretical description of the received signal. Section IV provides simulations from a typical indoor positioning situation in standard conditions in order to illustrate the interference influences and to study solutions that could be carried out to mitigate them. Section V summarises the paper and describes future works.