Ericsson Radio Systems AB PKRC1311004-1 Manual De Usuario

Encryption

This function is initiated during the set up of an encrypted channel
between MS and RBS. The BSC controls initiation of encryption mode.

Description

To set up a dedicated logical channel, encryption mode has to be set.
The RBS supports two encryption modes, "No encryption shall be
used"and "encryption" (encrypted by a specific GSM encryption
algorithm), see /GSM 08.58/. The RBS receives information of which
encryption mode to use, from BSC in a Channel_Activation message
containing "Encryption Information" (via ABIS RSL interface). This
command starts the function, and the traffic channel is encrypted
according to chosen algorithm.

The function is terminated when a "Channel_Activation_ Acknowledge"
is sent to BSC.

26.3

Encryption Mode Change

Purpose

This function is used to change the encryption mode (key and
algorithm) on an established dedicated channel.

Precondition and initiation

Encryption Mode change is defined in the section above.

This function is initiated when RBS receives an Encryption Command
from BSC.

Description

The RBS starts deciphering when the encryption command is received.
A Ciphering Mode Command is sent to start the encryption at the MS.
The MS then sends a Ciphering Mode Complete /GSM 04.08:-9.1.10/
as an acknowledgement to the RBS.

When the RBS receives a Ciphering Mode Complete, the encryption is
initiated in the network, and a DI (Data Indication) is sent back to the
BSC.

230 (421)

EN/LZT 720 0008

R1A

2001-06-26