Physical Layer Security 137
physical layer security can be used either to provide direct secure data communication
or to facilitate the distribution of cryptographic keys in the 5G networks [29].
Figure 6.14 depicts how the WBPLSec can be applied to 5G networks. In accordance
to the schema already presented in this chapter, the base station (BS), marked as Alice,
sends the watermarked signal to the mobile terminal (MT), marked as Bob. We assumed
that Bob has multiple radio interfaces to both receive and jam the received signal. The
WBPLSec technique creates a secure region around Bob, in which any other MT, such
as Eve, cannot eavesdrop the information.
In the previous sections, we assumed isotropic antennas for all the stakeholders
involved in the communication. On the other hand, future cellular network will exploit
the smart antenna technology to improve the SINR to the legitimate receiver, Bob.
Exploiting the smart antennas installed in the BS, Alice can enhance the directivity and
the Bob’s SINR, as shown in Figure 6.15. This produces an advantage to Bob regarding
to Eve and the secure region around will be wider.
W at er m ar ke d si gn al
MT
BOB
EVE
BS
ALICE
5G
j a m m i n g
Figure 6.14 WBPLSec applied
to 5G network.
EVE
G T = 1
MT
BOB
5G
BS
ALICE
G T < 1
Figure 6.15 Enhancement of the
WBPLSec security region in the context
of cellular network.