An Assisted GPS Acquisition Method using L2 Civil Signal in Weak Signal Environment

Deuk Jae Cho, Chansik Park, Sang Jeong Lee

Department of Electronics, Chungnam National University, Korea.
Division of Electrical and Computer Engineering, Chungnam National University, Korea.
School of Electrical and Computer Engineering, Chungbuk National University, Korea.

DOI:                 

Abstract

Recently, there has been increasing demands on the positioning capability in weak signal environment such as inside building and urban area. The present assisted GPS technology uses GPS L1 signals only. Meanwhile, according to the GPS modernization plan, Block IIR-M GPS satellite will be first launched in 2005, transmitting the civil code in L2 frequency as well as in L1 frequency with the updated signal structure. Since the L2 civil code has a worst-case cross correlation performance of 45 dB (over 251 times better than 21 dB cross correlation performance of the L1 C/A code), it will be much more effective in weak signal environment. This paper proposes an assisted GPS acquisition method using L2 civil signals. It will show that the acquisition success rate of the proposed assisted GPS acquisition method is better than that of the existing assisted GPS method using L1 signals in the same environment. The constellation of the next generation GPS satellites is scheduled to launch in 2005. Therefore, in order to design and test the assisted GPS acquiring the L2 civil signal, it is necessary to design a signal generator which can generate the L2 civil signal. The signal generator will be designed using the pseudo random noise (PRN) code generation method and navigation message protocol defined in GPS ICD PIRN 200C-007B. Finally, through the simulations using the designed signal transmitter, the success rate of the proposed assisted GPS acquisition method will be compared with that of the existing assisted GPS method to show the performance improvements.

Keywords

Acquisition, L2 Civil Signal, Weak Signal

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	C. Kee; H. Jun; D. Yun (2000): Development of Indoor Navigation System using Asynchronous Pseudolites, Proceedings of the ION GPS-2000, 1038-1045.
[2]	F. van Diggelen; C. Abraham (2001): Indoor GPS Technology, Presented at CTIA Wireless-Agenda, Dallas.
[3]	M.M. Chansarkar; L. Garin (2000): Acquisition of GPS signals at very low signal to noise ratio, Proceedings of the ION 2000 National Technical Meeting, 731-737.
[4]	Richard D. Fontana; Wai Cheung; Tom Stansell (2001): The Modernized L2 Civil Signal, GPS World Magazine, 28-34.
[5]	Richard D. Fontana; Wai Cheung; Paul M. Novak; Tom Stansell (2001): The New L2 Civil Signal, Proceedings of the ION 2001 International Technical Meeting, 617-631. Sang Jeong Lee; Deuk Jae Cho; Sang Hyun Park (2003): A Digital Correlator Design for Assisted GPS, Proceedings of the International Symposium on Information Science and Electrical Engineering 2003 (ISEE 2003), ACROS Fukuoka, Japan, 275-278.
[6]	S.G. Glisic, et al. (1999): New PN code acquisition scheme for CDMA network with low signal-to-noise ratios, IEEE Transactions on communications, Vol. 47, No. 2.
[7]	S. Soliman; S. Glazko; P. Agashe (1999): GPS receiver sensitivity enhancement in wireless applications, Proceedings of 1999 IEEE MTT-S Symposium, 181-186.
[8]	T. Haddrell; A. R. Pratt (2001): Understanding the indoor GPS signal, Proceedings of the ION 2001 International Technical Meeting, 1487-1499.
[9]	T. Hartman; L. Boyd; D. Koster; J. Rajan; J. Harvey (2000): Modernizing the GPS Block IIR Spacecraft, Proceedings of the ION GPS-2000, 2115-2121.
[10]	W. Marquis (2001): M is for Modernization: Block IIR-M Satellites Improve on a classic, GPS World Magazine, 38-44.