Carrier to noise power estimation for enhanced sensitivity Galileo/GPS receivers

Most market surveys predict exceptionally strong growth for location based services on mobile phone platforms. However, conventional GPS receivers cannot satisfy the requirements for these applications. Enhanced reception sensitivity is particularly important for next generation consumer market Galileo/GPS receivers targeted for location based services, E-911, and moderate indoor reception. Moderate indoor reception requires sensitivities in the range of -185 dBW carrier power corresponding to a 20 dBHz ratio of carrier power to noise power spectral density. This paper shows how carrier to noise power estimation can significantly improve the reception sensitivity of Galileo/GPS receivers. Statistical signal processing techniques are applied to derive the difference in probability of detection between a receiver that has no knowledge of the carrier to noise power and one that can use the knowledge of carrier to noise power to optimally adjust the acquisition detection threshold. Simulation results are provided for a GPS C/A receiver with 20 ms coherent integration time. The maximally achievable sensitivity gain is 3.2 dB for 30 ms total observation time, 4.3 dB for 100 ms, 5.8 dB for 300 ms, 7.7 dB for 1 s, 9.6 dB for 3 s, and 12 dB for 10 s. Furthermore, this paper analyzes a suitable method for carrier to noise power estimation based on the second and fourth non-central moments. Simulation results for the convergence of this estimation method are also provided