Positioning is next to communication the most important field of applications for wireless radio transmissions. In indoor scenarios, multipath reception degrades the accuracy of time of arrival based position estimation as long as the receiver uses standard methods. Strategies to mitigate multipath effects on ranging estimates are in general based on the estimation of the channel impulse response. All these methods have in common that they determine the multipath in order to remove the influence on the delay estimate of the line-of-sight path. ChannelSLAM, however, accurately estimates the position by using multipath compared to traditional mitigation approaches. Measurements with a moving receive antenna showed, that multipath components are visible for several meters of receiver movement. For positioning, the novel approach treats multipath components as signals from virtual transmitters which are time synchronized to the physical transmitter and fixed in their position. Therefore, multipath propagation increases the number of transmitters such that the position estimation accuracy can be improved. The proposed ChannelSLAM algorithm is able to estimate and track the receiver position using only one physical transmitter, without requiring any prior information such as room layout or a database for finger printing.