A receiving device is disclosed that receives a non-EHT PPDU that includes a service field and that is sent by a sending device, where the service field includes a first field whose bit quantity is m, and m≥1; and the receiving device determines, based on the first field, an initialization state of a scrambling code sequence corresponding to an extremely-high throughput physical layer protocol data unit EHT PPDU, where a bit quantity of the initialization state of the scrambling code sequence is greater than the bit quantity of the first field.