Sensing method and apparatus, and system

A sensing method, wherein the method comprises:

• receiving, by a second device from a first device, a training unit, wherein a quantity of training subfields for one station (STA) in the training unit is based on a quantity of second devices participating in sensing measurement;
• wherein when the quantity of second devices participating in the sensing measurement increases, the quantity of training subfields for one STA decreases;
• and
• processing, by the second device, the training unit.

A first device, comprising:

• at least one processor;
• a transceiver that is coupled to the at least one processor;
• and
• a communication interface receiving programming instructions, wherein the at least one processor executes the programming instructions to determine a quantity of training subfields for one station (STA) in a training unit based on a quantity of second devices participating in sensing measurement;
• wherein when the quantity of second devices participating in the sensing measurement increases, the quantity of training subfields for one STA decreases;
• and
• wherein the transceiver is configured to send the training unit to a second device.