GPS and advanced MEMS technology can overcome the combination of poor accuracy of the shortcomings. Acceleration sensors and gyroscopes based on MEMS technology, with a very small size, is very easy to integrate GPS systems. DR system but to enhance the accuracy, often on-line sensor calibration, then the position on the need for GPS signals to fix the parameters of DR sensors; In addition, MEMS can be realized while high-precision, but because of its high cost, which The inevitable rise in costs.

Forward-looking technology 2: Galileo project
GPS has now been familiar and widely applied, but some people may not know the actual structures by the U.S. military's global satellite navigation system. Other countries in the world in the commercial and national security, and other factors to consider, also are planning similar navigation systems.

Galileo plan is led by the EU; its operating units are private organizations, major technology from the European Space Agency (ESA). Since the scheme by private business institutions, markets and profits is the largest of its consideration, the Galileo project planned for a total of three different frequencies: Lower L-band the E5a and E5b, Middle L-band and the Upper L-E6 band of E2-L1-E1, to provide differentiated services fees.

Galileo provide a total of four service levels, that is, open services (OS), life and safety services (SoL), business services (CS), and public service regulations (PRS), which SoL and CS is to pay for, free of charge An operating frequency in 1560 - 1591MHz between, with the GPS 1575.42 MHz use the same antenna reception. Galileo used special modulation techniques to reduce the multi-path interference, and improve the accuracy of business; its horizontal and vertical direction can be achieved respectively four meters and eight meters accuracy.

Galileo and GPS and GNSS systems have interoperability, an integrated GPS and Galileo systems of the two duplex mode receiver than the accuracy of the above-mentioned values can enhance one another, that is, the horizontal direction can be Of 3 to 4 meters, vertical direction for six to eight meters.

Galileo project will require a total of 30 satellites launched so that any place can see four more satellites, but the Galileo satellite orbit and the equatorial plane of the greater inclination to reach 56 degrees, the high latitudes of the Nordic region Can provide better services. Galileo's first satellite (GIOVE-A) was successfully launched by the end of 2005, is expected in 2008 will officially open commercial use.

Table 1 The specifications difference between GPS and Galileo

Conclusion
Automotive GPS navigation system is currently a prospect market, but in the future integration of services and technology, it also faces many challenges. More closely combination of GPS and communications systems is one of the future trends. The integrated system can provide transportation, tourist attractions information, and other LBS services. The introduction of DR functions, the system will be able to achieve continuous positioning navigation. In addition, since the implementation of Galileo, it is expected it will form a dual-mode with GPS in the next-generation navigation system.