Method and device for processing timing advance (ta), and method and device for sending indication information

A method for processing a timing advance (TA), comprising:

• in response to a TA of a terminal being in an invalid state, executing one of the following operations:
• sending, by the terminal, a random access signal used for a non-contention-based random access procedure;
• sending, by the terminal, a random access signal on a first-type resource;
• sending, by the terminal, a random access signal used for a contention-based random access procedure;
• receiving, by the terminal from a base station, signaling that triggers the non-contention-based random access procedure;
• or
• receiving, by the terminal from the base station, a signaling that triggers the contention-based random access procedure.

A method for sending indication information, comprising:

• sending, by a terminal, first indication information to a base station;
• wherein the first indication information indicates at least one of the followings:
• a timing advance (TA) of the terminal is in an invalid state;
• the terminal fails to receive from the base station hybrid automatic repeat request acknowledgement information (HARQ-ACK) feedback information for uplink data sent on a first-type resource;
• a coverage enhancement level of the terminal changes;
• a serving cell of the terminal changes;
• a number of repeatedly sending by the terminal the uplink data sent on the first-type resource changes;
• or
• a service mode of the terminal corresponding to the uplink data sent on the first-type resource changes.