Enhanced Error Correction for Satellite Navigation Message Based on CRC Codes

To improve the performance of satellite navigation by using error messages, an enhanced error correcting method based on CRC code was proposed. The CRC-24 error checking code of navigation message was used to correct one-bit error pattern. The minimum hamming weight and error correcting capability of CRC-24 code were proved by mathematical analysis and computer searching. The performance improvement of navigation using CRC correction was analyzed based on message format and the model of error bit distribution. A low complexity implementation was schemed based on looking-up table. The performance of enhanced error correcting was simulated with GPS CNAV navigation message. The results show that the CRC-assisted correction can reduce frame error ratio by 1~2 orders of magnitude. Without changing the signal structure of navigation message, the reliability of navigation is improved by using the enhanced correction.