Performance enhancements for embedded software implementation of GNSS navigation algorithms

Calculation of a navigation solution in a GNSS receiver requires a number of different calculations to be carried out. In this paper, a number of software optimizations that can be used in the calculation of a navigation solution without decreasing the accuracy of the result are presented. Also, some optimizations that appeared to be unsuitable for navigation solution and could not be used are shown. Some attention is put on limited capabilities of embedded hardware (e.g. single-precision FPU) that may be used in GNSS receiver. Software was implemented in ANSI-compatible C language, built for ARM platform and executed on ARM instruction set simulator. Its performance was measured in execution time and estimated Whetstone FLOPs. Presented complexity budget shows the amount of calculations required by each stage of the solution.