a first transmitter, transmitting a first signal;

wherein the first signal carries a target identifier, the target identifier being either a first identifier or a second identifier; when the target identifier is the first identifier, the first signal carries a first message; when the target identifier is the second identifier, the first signal carries a second message; a first logical channel is used for bearing the first message, while a second logical channel is used for bearing the second message, the first logical channel being different from the second logical channel, the first message and the second message coming from an Access Stratum; the first signal carries a first data block, the first data block being from a Non-Access Stratum; a size of the first signal is used to determine the target identifier; the first node is in a Radio Resource Control (RRC) Inactive state when transmitting the first signal; the first identifier includes a Medium Access Control (MAC) layer identifier; the second identifier includes a Medium Access Control (MAC) layer identifier; the first data block comprises a PDCP SDU.