Patent ID: 11962479
Assignee: PANASONIC INTELLECTUAL PROPERTY CORPORATION OF AMERICA
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 8:
9. The abnormality detection method according to claim 3, further comprising:
calculating, for each of one or more reference packet streams made up of a plurality of reference packets that are consecutive, each of a plurality of reference distances between the plurality of reference packets; and
extracting, using each of the plurality of reference distances calculated, a reference feature amount of a corresponding one of the one or more reference packet streams, wherein
in the calculating of each of the plurality of reference distances, a Levenshtein distance between payloads of the plurality of reference packets is used to calculate each of the plurality of reference distances,
the Levenshtein distance between the payloads of the plurality of reference packets is calculated for each pair of reference packets that are N packets apart from each other in each of the one or more reference packet streams, and the calculation is applied in units of M bits to at least a portion of bit strings included in the payloads, N being an integer greater than or equal to 1, M being an integer between 1 and 16, inclusive, and
in the extracting of the reference feature amount of each of the one or more reference packet streams, for each of one or more windows made up of W consecutive reference packets in each of the one or more reference packet streams, a frequency distribution of the plurality of reference distances calculated for pairs of reference packets belonging to the window is calculated, the frequency distribution of the plurality of reference distances calculated is extracted as the reference feature amount of the reference packet stream, and the reference feature amount of the reference packet stream that has been extracted is stored as a corresponding one of the plurality of reference frequency distributions stored in advance, W being an integer greater than or equal to 2.