Application of the Recursive Signal processing of the Floating Solution in Multipath Environment

In general, a roving user experiences a limitation in the performance of a floating solution because it carried out independent signal processing of a single epoch measurement value for every epoch. The existing carrier-phase differential GPS (CDGPS) using multi-epoch measurements is capable of achieving good floating solution performance because it employs a batch signal processing technique aimed at precise positioning at a fixed location. However, because it uses the measurement values in all epochs, it has the drawback of an exponential increase in the computational cost. In this paper, we apply a recursive signal processing technique for improving the performance of an initial floating solution for the roving users of the CDGPS. The applied signal processing technique estimates a floating solution at the current time using a position determined by the measurements at the previous times and the measurement at the current time. The applied signal processing technique incurs a computational cost comparable to that of the epoch-by-epoch signal processing technique and demonstrates the same floating solution performance as the batch signal processing technique, as proven in tests using actual signals in multipath environment. Users at a fixed position use multi-epoch measurements to determine the accurate initial position and integer ambiguities. The batch signal processing technique using the existing multi-epoch-based batch signal processing technique has the drawback of an exponentially increasing computational cost as the number of multi-epoch measurements increase. This makes it inappropriate for roving users, and therefore, it has been mostly used for post-processing precise positioning The recursive signal processing technique proposed in this paper improved floating solution precision and reduced computational cost as compared to the existing epoch-by-epoch and batch signal processing techniques by effectively employing multi-epoch measurements. The performance analysis results revealed that the applied technique had a performance level comparable with the batch signal processing technique and exhibited a computational time similar to that of the existing epoch-by-epoch signal processing technique despite the increased multi-epoch measurements in multipath environment.