High Sensitivity Techniques for GNSS Signal Acquisition - Global Navigation Satellite Systems: Signal,Theory and Applications - page 29

chosen to be the decision variable

m = 1 max S ( B − C ) , m , S ( B + C ) , m

M

=

S CC M (55)

The analytical expressions of the performance parameters of these strategies are presented in
(Ta et al., 2010).

6.2 Performance analyses

Fig. 13 clearly shows the improvement of the joint data/pilot strategies over the conventional
SC. The benchmark values P fa 10 − 3 0.9 for the hypothesis testing in GNSS

receivers are used to quantitatively estimate the improvement.

=

and P d

=

When only one full code

2.8 (dB ) 1 .8 (d B )

Joint Strategies

$

$

&

&

10 − 3 : (a) Fig. 13. Detection probability of all the strategies vs. C / N 0 values when P fa =

M

=

1; (b) M

=

50

period is considered (i.e. M

=

1), as shown in Fig. 13(a), the joint data/pilot strategies holds

the sensitivity enhancement 3 dB over the conventional SC. Among the joint strategies, the

assisted (B-C) outperforms the others, because the assistance data always guarantees the local
generated signal matching the most to the received one. As for the other stand-alone joint
strategies, the difference in P d is small, but one still can realize that CC is the best one.
When K

∼

50, the assisted (B-C) is far better than the others, because the coherent combination
applied in this strategy brings more performance improvement than the other strategies using
the non-coherent technique suffering from the squaring loss phenomenon. This loss also
reduces the enhancement (from 2.8 dB to 1.8) dB) of the stand-alone joint strategies with
respect to the SC, see Fig. 13(b). Among the stand-alone joint strategies, in this scenario,
DC takes the position of CC to be the best.

=

×

While (B C) degrades significantly, because

unlike K 1, to secure the accumulation, the absolute values of the differential

operation's outputs are used in the non-coherent combination. This fact makes the averaging
not thorough.

=

1, for K

>

Fig. 14 shows the T A values of all the strategies. It should be note that T A simultaneously
consider the influences of both the computational complexity and the sensitivity of a strategy.