Integration of different types of sensors for navigation is essential to incorporate the best of their features for more robust and accurate positioning. Global Positioning System (GPS) and NavIC systems provide poor vertical position accuracy. This can be improved by integrating ground-based pseudolites (Pseudo-satellites) with NavIC & GPS. Integration of GPS, NavIC & Pseudolite systems not only improves position accuracy & signal availability but also reduces geometrical errors, especially Vertical Dilution of Precision (VDOP). Therefore, in this paper, a detailed analysis of positioning performance of combined GPS, NavIC and Pseudolite systems has been done using simulated data of GPS & NavIC generated from Spirent simulator combined with Pseudolite data from an identified location in India. Furthermore, data was corrupted by introducing Gaussian noise of 10 m mean & standard deviation of 3 m into generated ranges of GPS, NavIC & Pseudolite to assess the effect on position accuracy in the presence of noise. It has been observed from the analysis that the 3D position accuracy of combined GPS, NavIC & Pseudolite systems is reduced to 1.75 m from 10 m with NavIC only position. This is particularly useful for aviation applications where better vertical position accuracy is required.