High Sensitivity Techniques for GNSS Signal Acquisition - Global Navigation Satellite Systems: Signal,Theory and Applications - page 30

& &

× ×

' '

10 − 3 : (a) M

Fig. 14. Mean acquisition time T A vs. C / N 0 values when P fa =

=

1; (b) M

=

50

For all C / N 0 and K values, (B-C) results in the smallest T A , because of its high sensitivity
(i.e. detection capability) and also moderate complexity (only one correlator required, but
assistance is needed). For K

= ≤ < 1 and 33 (dB-Hz) C / N 0 36 (dB-Hz), due to the significant

× sensi tiv ity improvement of the DC, (B C), and CC strategies with respect to the SC strategy,

their T A values are smaller than that of the SC strategy, see Fig. 14(a). However, for C / N 0 ≥
35.7 (dB-Hz), the sensitivity improvement of the SC strategy is sufficient to reduce its T A
to be lower than that of the stand-alone joint strategies. For K = 50, due to the sensitivity

improvement of all the strategies, the turning point appears earlier at C / N 0 = 24.3 (dB-Hz).

see Fig. 14(b).

7. Conclusions

This Chapter focused on high sensitivity signal acquisition problems. Throughout the
chapter, some challenges to HS signal acquisition such as unknown data transitions, Doppler
effects on carrier frequency and PRN code rate, local oscillator instability as well as
sensitivity-complexity trade-off were discussed in details in order to define the requirements
of HS acquisition strategies suitable for different operational scenarios. Then three HS
acquisition approaches, namely stand-alone, external-aiding and channel combining, have
been introduced. Finally, the applications of these approaches to specific GNSS signals are
demonstrated for readers' better understanding.

8. References

3GPP (2008a). Radio resource control (RRC) - release 7, Organizational Partners .
3GPP (2008b). Radio resource LCS protocol (RRLP) - release 7, Organizational Partners .
Audoin, C. & Guinot, B. (2001). The Measurements of Time - Time, Frequency and the Atomic Clock ,
Cambridge University Press.
Betz, J. W. (2001). Binary Offset Carrier Modulations For Radionavigation, Journal of Navigation
48: 227-246.
Chansarkar, M. & Garin, L. (2000). Acquisition of GPS Signals at Very Low Signal to Noise
Ratio, Proceedings of the 2000 National Technical Meeting of the Institute of Navigation
(ION NTM 2000), Anaheim, CA, USA , pp. 731-737.