Delay measurement method and apparatus

A delay measurement method, comprising:

• sending, by a second communications device, a data unit to a first communications device, wherein the data unit comprises time information, wherein the time information is used to indicate a first moment at which the second communications device sends the data unit, and wherein the time information includes a part of bits of a frame number at the first moment;
• and
• receiving, by the second communications device, delay information from the first communications device, wherein the delay information indicates a delay from the second communications device to the first communications device, wherein the delay is determined based on the first moment and a second moment, and wherein the second moment is a moment at which the first communications device receives the data unit.

A delay measurement apparatus, wherein the apparatus is a first communications device and comprises:

• a receiver, the receiver configured to receive a data unit from a second communications device, wherein the data unit comprises time information, wherein the time information is used to indicate a first moment at which the second communications device sends the data unit, and wherein the time information includes a part of bits of a frame number at the first moment;
• and
• at least one processor, the at least one processor configured to determine a delay from the second communications device to the first communications device based on the first moment and a second moment, wherein the second moment is a moment at which the first communications device receives the data unit.

A delay measurement apparatus, wherein the apparatus is a second communications device and comprises:

• a transmitter, the transmitter configured to send a data unit to a first communications device, wherein the data unit comprises time information, wherein the time information is used to indicate a first moment at which the second communications device sends the data unit, and wherein the time information includes a part of bits of a frame number at the first moment;
• and
• a receiver, the receiver configured to receive delay information from the first communications device, wherein the delay information indicates a delay from the second communications device to the first communications device, wherein the delay is determined based on the first moment and a second moment, and wherein the second moment is a moment at which the first communications device receives the data unit.