A Novel IM Sync Message-Based Cross-Device Tracking

Table 1

Summary of notations.

Symbol	Meaning
,	An outgoing packet, an incoming packet
,	The set of devices, the set of users
,	The set of personal computers, the set of mobile phones
	The set of sync message timestamps of the PC
	The set of sync message timestamps of the mobile phone
	The set of sync message timestamps of the PC and the mobile phone successfully matched
	The result of matching sync messages in the mobile phone with the message of the PC
	The likelihood ratio
	The probability of sync message matching when two devices are not correlated
	The probability of sync message matching when two devices are correlated
,	The upper boundary, the lower boundary
,	The false-positive rate, the false-negative rate
	The average time interval between user receiving sync messages
	The packet interval threshold
	The time offset of the network environment