Synchronization information sending method, synchronization information receiving method, base station, and communications node

A communications node, comprising:

• a receiving unit, configured to receive a subframe and an identifier of the subframe that are sent by a base station;
• a processing unit, configured to:
• obtain a pulse per second (PPS);
• obtain a first time T1 based on the PPS;
• obtain a second time T2 based on the subframe received by the receiving unit, wherein the second time T2 is a time at which the subframe arrives at the communications node;
• determine a first time difference (TD) 1 based on a difference between the first time T1 and the second time T2;
• obtain a timing advance (TA) corresponding to the base station;
• and
• obtain a second time difference (TD) 2 based on the first time difference (TD) 1 and the TA, wherein the second time difference (TD) 2 is a difference between a time at which the base station sends the subframe and the first time T1;
• and
• a sending unit, configured to send the second time difference (TD) 2, the first time T1, and the identifier of the subframe to the base station.

A synchronization information receiving method, comprising:

• sending, by a base station, a subframe and an identifier of the subframe to a communications node;
• receiving, by the base station, a second time difference (TD) 2, a first time T1, and the identifier of the subframe that are sent by the communications node, wherein
• the first time T1 is obtained based on a pulse per second PPS obtained by the communications node, and
• the second time difference (TD) 2 is obtained based on a first time difference (TD) 1 and a timing advance (TA), wherein
• the second time difference (TD) 2 is a difference between a time at which the base station sends the subframe and the first time T1,
• the first time difference (TD) 1 is determined based on a difference between the first time T1 and a second time T2,
• the second time T2 is obtained based on the subframe and being a time at which the subframe arrives at the communications node, and
• the TA is a TA corresponding to the communications node and the base station;
• and
• adjusting, by the base station, a sending time of a to-be-sent subframe and an identifier of the to-be-sent subframe based on the second time difference (TD) 2, the first time T1, and the identifier of the subframe.