LAMBDA – Least-squares Ambiguity Decorrelation Adjustment

The LAMBDA method is a statistics-based computational method for solving the integer least-squares estimation problem arising in carrier-phase GNSS positioning and other mixed integer-real estimation problems. The method maximizes the ambiguity success-rate, i.e. probability of correct integer estimation, within the class of elliptically contoured distributions.

The LAMBDA method achieves computational efficiency by combining its sequential conditional integer search with an integer-preserving decorrelating transformation of the carrier-phase ambiguities. The method is widely used in high-precision GNSS positioning, such as real-time kinematic (RTK) positioning, precise point positioning with ambiguity resolution (PPP-AR), carrier-phase attitude determination, and array-based precise pose (A-PPP) determination.