System message transmission method, terminal device, and network device

A system message transmission method, wherein the method is executed by a relay terminal, and the method comprises:

• receiving a first request for system information SI or system information block SIB sent by a remote terminal;
• and
• sending a target SI or SIB to the remote terminal;
• wherein the sending a target SI or SIB to the remote terminal comprises at least one of the following:
• in a case that the stored SI or SIB does not match the system message currently broadcast by the network device, sending a second request for SI or SIB to the network device to obtain the target SI or SIB;
• and
• in a case that no SI or SIB is stored, sending a second request for SI or SIB to the network device to obtain the target SI or SIB;
• wherein the obtaining the target SI or SIB comprises:
• in a case that a first trigger condition is satisfied, receiving the target SI or SIB sent by the network device through broadcast or by using dedicated RRC signaling, wherein the first trigger condition comprises:
• Uu quality being lower than a predetermined threshold, the remote terminal being located out of network coverage, and a PC5 connection between the remote terminal and the relay terminal having been established successfully;
• wherein the obtaining the target SI or SIB further comprises:
• in a case that a second trigger condition is satisfied, receiving the target SI or SIB sent by the network device by using dedicated RRC signaling, wherein the second trigger condition comprises:
• that a prohibit timer for allowing a dedicated SI or SIB request has been configured and the prohibit timer is in a non-running state;
• wherein, after the sending, by the remote terminal, a first request for system information SI or SIB to a relay terminal,
• the prohibit timer is started or restarted;
• and
• the prohibit timer is stopped after the target SI or SIB sent by the relay terminal is received by the remote terminal;
• wherein before the receiving, by the remote terminal, a target SI or SIB sent by the relay terminal,
• the prohibit timer is stopped in a case that a stop timing condition is satisfied, wherein the stop timing condition comprises at least one of the following conditions:
• that radio link transmission fails on a sidelink between the remote terminal and the relay terminal;
• that a PC5 connection between the remote terminal and the relay terminal has been released;
• and
• that a reselection condition for the relay terminal is satisfied.

A system message transmission method, wherein the method is executed by a network device, and the method comprises:

• receiving a second request for SI or SIB sent by a relay terminal, wherein the second request comprises a SI or SIB requirement of a remote terminal;
• and
• sending a target SI or SIB in response to the second request;
• wherein the sending the target SI or SIB comprises:
• in a case that a first trigger condition is satisfied, sending the target SI or SIB through broadcast or by using dedicated RRC signaling, wherein the first trigger condition comprises:
• Uu quality being lower than a predetermined threshold, the remote terminal being located out of network coverage, and a PC5 connection between the remote terminal and the relay terminal having been established successfully;
• wherein the sending the target SI or SIB further comprises:
• in a case that a second trigger condition is satisfied, sending the target SI or SIB by using dedicated RRC signaling, wherein the second trigger condition comprises:
• that a prohibit timer for allowing a dedicated SI or SIB request has been configured and the prohibit timer is in a non-running state;
• wherein, after the sending, by the remote terminal, a first request for system information SI or SIB to a relay terminal,
• the prohibit timer is started or restarted;
• and
• the prohibit timer is stopped after the target SI or SIB sent by the relay terminal is received by the remote terminal;
• wherein before the receiving, by the remote terminal, a target SI or SIB sent by the relay terminal,
• the prohibit timer is stopped in a case that a stop timing condition is satisfied, wherein the stop timing condition comprises at least one of the following conditions:
• that radio link transmission fails on a sidelink between the remote terminal and the relay terminal;
• that a PC5 connection between the remote terminal and the relay terminal has been released;
• and
• that a reselection condition for the relay terminal is satisfied.