Question: What is the purpose of the DIRECTION bit in the ciphering algorithm NEA?
Option 1: To determine the length of the keystream required
Option 2: To identify whether the transmission is uplink or downlink
Option 3: To specify the type of encryption used
Option 4: To indicate the bearer identity
Explanation: The DIRECTION bit is a critical input parameter in the ciphering algorithm NEA, and its purpose is to identify whether the transmission is uplink (0) or downlink (1). This information is essential for generating the correct keystream and ensuring secure encryption of the plaintext.