Page 38 - Use cases and requirements for the vehicular multimedia networks - Focus Group on Vehicular Multimedia (FG-VM)

Figure 11 – Convergence of different networks for vehicular multimedia content

Consider live television service as an example. Currently, live television service is delivered solely
by satellite broadcast network. To protect the television video content from being received at
unauthorized terminals, the following conditional access (CA) technique is applied. The architecture
of the satellite broadcast system with CA support is illustrated in Figure 11. At the head end, the
multimedia stream for each channel is scrambled by a control word (CW). The CW is encrypted by
the product key (PK) to obtain the entitlement control message (ECM). The PK is encrypted by the
personal distribution key (PDK) to obtain the entitlement management message (EMM). Scrambled
data, ECMs, and EMMs are multiplexed into a transport stream (TS) before it is transmitted over
satellite broadcast channels. At the terminal, the transport stream is demultiplexed to recover the
scrambled data, ECMs, and EMMs. Then, the PK is decrypted from the EMM by the PDK stored at
the CA terminal. Next, the CW 1 for channel 1 is decrypted from the ECM by the PK. Finally, the
multimedia stream for channel 1 can be obtained by descrambling the data for channel 1 with CW 1.
Note that PDK is unique for each terminal, and, therefore, the EMM for a terminal would be different
from those for other terminals. By using the above CA technique, for each terminal the access to the
live television service can be controlled (i.e., access to the content is either allowed or denied).

28 FGVM-01R1 (2019)