The invention provides a nominal packet filling value indication method, a nominal packet filling value determination method and a
communication device, which are used for reducing the overhead of a
physical layer packet extension threshold field. The indication method comprises: a first device generating a PPDU and sending the PPDU to a second device, a
physical layer packet extension threshold
information field included in the PPDU comprising a plurality of packet extension threshold sub-field sets corresponding to different nominal packet filling values, each packet extension threshold sub-field set being used for indicating a modulation threshold corresponding to an RU with an NSS of n and a serial number of b, when the value of the RU index
mask field of the RU with the serial number of y is 0, the value range of b does not include y; in the packet extension threshold sub-field set corresponding to the same nominal packet filling value, the value of the RU index
mask field of the RU with the serial number being y is 0 and is used for indicating that NSS is n, the modulation threshold of the RU with the serial number being y is the modulation threshold corresponding to the RU with the serial number being m1, and NSTS is n.