The analysis of patterns in communications for the purpose of gaining intelligence about a system or its users. Traffic analysis does not require examination of the content of the communications, which may or may not be decipherable. For example, an adversary may be able to detect a signal from a reader that could enable it to infer that a particular activity is occurring (e.g., a shipment has arrived, someone is entering a facility) without necessarily learning an identifier or associated data.
Sources:
NIST SP 800-98
under Traffic Analysis