Timing advance TA determining method and communications apparatus

A method for determining timing advance, comprising:

• obtaining, by a terminal, a first parameter and a second parameter, wherein the first parameter comprises positioning information of the terminal, and the second parameter comprises one or more of the following information:
• ephemeris information of a serving satellite, or common timing advance (TA) information;
• updating, by the terminal, the first parameter or the second parameter at a first moment;
• receiving, by the terminal, a timing advance command (TAC) at a jth moment, and updating a first timing advance value NTA based on the TAC, wherein the jth moment is an invalidation moment of the first parameter or the second parameter, or the ith moment is a moment before the invalidation moment of the first parameter or the second parameter, and 2≤j<N;
• and
• determining, by the terminal at an Nth moment, a TA adjustment value based on a component of updated NTA at an (N−1)th moment, and communicating with the serving satellite based on the TA adjustment value, wherein the component of NTA is αNTA, and 0≤α≤1.

A communications apparatus implemented in a terminal, comprising:

• at least one processor;
• and
• one or more memories coupled to the at least one processor and storing programming instructions for execution by the at least one processor to perform operations comprising:
• determining a validity duration of a first parameter and a validity duration of a second parameter, wherein the first parameter comprises positioning information of the terminal, and the second parameter comprises one or more of the following information:
• ephemeris information of a serving satellite, or common timing advance (TA) information;
• determining an invalidation moment of the first parameter and an invalidation moment of the second parameter based on a validation moment of the first parameter, a validation moment of the second parameter, the validity duration of the first parameter, and the validity duration of the second parameter;
• updating the first parameter and the second parameter at or before an earlier invalidation moment in the invalidation moment of the first parameter and the invalidation moment of the second parameter;
• determining a TA adjustment value based on an updated first parameter and an updated second parameter;
• and
• communicating with the serving satellite based on the TA adjustment value.