Small data transmission method and apparatus, and terminal device

A terminal device, comprising:

• a processor and a memory, wherein the memory is configured to store a computer program, and the processor is configured to call and run the computer program stored in the memory to perform a method for transmitting small data, comprising:
• determining a first data volume, wherein the first data volume comprises a data volume of pending UL data across all Radio Bearers (RBs);
• and
• determining whether to initiate inactive small data transmission based on the first data volume,
• wherein the determining whether to initiate the inactive small data transmission based on the first data volume comprises:
• determining to initiate the inactive small data transmission, if the first data volume is less than or equal to a first threshold and a channel quality measurement value measured by the terminal device is greater than or equal to a second threshold,
• wherein the method further comprises:
• receiving a system message sent by a network device,
• wherein the system message comprises one data volume threshold and one channel quality threshold, the one data volume threshold being the first threshold, and the channel quality threshold being the second threshold;
• and
• the method further comprises:
• comparing the first data volume with the data volume threshold;
• if the first data volume is less than or equal to the data volume threshold, comparing the channel quality measurement value with the channel quality threshold, and
• if the second threshold is less than or equal to the channel quality measurement value, indicating to an upper layer that conditions for initiating small data transmission procedure are fulfilled.

A method for transmitting small data, comprising:

• sending, by a network device, Radio Resource Control (RRC)-specific signaling to a terminal device, wherein
• the terminal device is configured to determine a first data volume, wherein the first data volume comprises a data volume of pending UL data across all Radio Bearers (RBs);
• the terminal device is further configured to determine whether to initiate inactive small data transmission based on the first data volume;
• the terminal device has N Data Radio Bearers (DRBs), where N is a positive integer;
• and
• the RRC-specific signaling carries first indication information, and the first indication information is used for indicating that M DRBs among the N DRBs support the inactive small data transmission, where M is a positive integer less than or equal to N,
• wherein the terminal device is further configured to:
• determine to initiate the inactive small data transmission, if the first data volume is less than or equal to a first threshold and a channel quality measurement value measured by the terminal device is greater than or equal to a second threshold,
• wherein the method further comprises:
• sending, by the network device, a system message to the terminal device,
• wherein the system message comprises one data volume threshold and one channel quality threshold, the one data volume threshold being the first threshold, and the channel quality threshold being the second threshold;
• and
• the terminal device is further configured to:
• compare the first data volume with the data volume threshold;
• if the first data volume is less than or equal to the data volume threshold, compare the channel quality measurement value with the channel quality threshold;
• and
• if the second threshold is less than or equal to the channel quality measurement value, indicate to an upper layer that conditions for initiating small data transmission procedure are fulfilled.