Page 206 - 卫星导航2021年第1-2合期

Wang et al. Satell Navig (2021) 2:4 Page 6 of 9

Table 1 Implementation complexity
Method Code sequence generator Percentage Correlator Percentage
number increased (%) increased
Non-authentication Authentication Non-authentication Authentication (%)

1 1 2 100 6 7 16.7
2 1 2 100 6 7 16.7
3 2 3 50 12 14 16.7

Fig. 6 Performance simulation of authentication module Fig. 7 C N degradation
0
Performance simulation of three authentication methods authentication codes is K , signal amplitude is A , and the
2
at receiver end power of noise is σ , then the C N of the non-authen-

0
Te simulation parameters are as follows: code rate tication signal is 2σ 2 2 · N . For the receivers which do not
A
R c = 1.023 Mcps , phase hopping amplitude ϕ PH = 5 , participate in authentication, the C N is A 2 2 · (N−K) 2 .

◦
N
C N = 40 dB·Hz, coherent integration time 1000 ms, So, the C N degradation is 0 2σ

0
0
and false alarm probability 10 .
−4
2
Te simulation result is shown in Fig. 6. In the fgure, �C N = 10 log (1 − p u ) (19)
10
0
"PN_I" represents the method of using the data chan-
nel for authentication, "PN_Q" represents the method where p u is the ratio of the authentication part in a signal,
of using the pilot channel for authentication. Te detec- that is, the ratio of the unpredictable sequence inserted in
tion probability curves of the two methods coincide. the spreading code sequence.
"Combination" represents the method of using both pilot For the binary phase hopping based SCA technique,

channel and data channel for authentication. When both the C N degradation is
0
channels are used, the signal power is fully utilized, so �C N 0 = 10 log (1 − p u ) (20)

its performance is optimal. Te coherent accumulation 10
time required to achieve the same detection probability is where p u is the ratio of the authentication part in a signal,
reduced by a half. and the relationship with the phase hopping amplitude is
2
p u = (sin ϕ PH ) (21)
Performance loss of receivers not participating
in authentication it is known that theoretically the C N degradation of
0
For the existing civil receivers which do not include iden- the binary phase hopping based SCA technique is lower,
tity authentication module. Te authentication compo- which is a half of that for the inserting chip based SCA
nent in the signal is regarded as noise, which will degrade technique.
C N . Figure 7 shows the simulation results of C N degrada-

0
0
For the inserting chip based SCA technique, assum- tion of the two SCA techniques. Te theoretical results
ing the spreading code length is N, the length of the coincide with the simulation results. Te binary phase