Prof. Gao from the University of IL has developed an algorithm to incorporate measurements from multiple low-cost, light weight GPS receivers on one UAV to improve accuracy and reliability.
They have implemented an Extended Kalman Filter for the purpose of integrating the pseudorange measurements from multiple receivers.
The measurement matrix in the EKF can be further extended to include the carrier phase measurements from the receivers – attitude.
Publication(s) - Shetty, Akshay, and Grace Xingxin Gao. "Measurement Level Integration of Multiple Low-Cost GPS Receivers for UAVs." Proceedings of the 2015 International Technical Meeting of The Institute of Navigation, Dana Point, California. 2015.