Communication method and apparatus
A communication method and apparatus are provided. The method includes: A source network device generates and sends a first message, where the first message is for handing over a terminal device from the source network device to a target network device, the first message includes first indication information, and the first indication information indicates to perform a random access-free process and/or a handover complete message-free process in a handover process. In this way, if cell jump occurs in a source cell, the terminal device may not perform a random access process and/or not send a handover complete message in a process of handover from the source cell to a target cell. This avoids uplink congestion of the target cell caused by simultaneous handover of a plurality of UEs to the target cell, effectively reduces signaling overheads, and improves network performance of a target base station.
1 . A communication method comprising:
sending, to a target network device, a first request message requesting a handover of a terminal to the target network device, the first request message comprising effective-time information of a handover configuration and first information indicating that the handover is for a satellite cell jump wherein a plurality of terminals, including the terminal, are handed over at a same time from a source cell of a source network device to a target cell of the target network device; and
sending a handover message, to the terminal, for handing over the terminal from the source network device to the target network device, the handover message comprising the effective-time information and indication information indicating to perform a random access-free process or a handover complete message-free process in a handover process.
2 . The method according to claim 1 , further comprising:
receiving a first acknowledgment message from the target network device indicating that the terminal is allowed to be handed over to the target network device.
3 . The method according to claim 2 , wherein the first acknowledgment message comprises second information or resource information, wherein
the second information is used by the terminal to determine a timing advance from the terminal to the target network device, and
the resource information indicates an uplink time-frequency resource scheduled for the terminal.
4 . The method according to claim 3 , wherein the second information indicates the timing advance from the terminal to the target network device, or the second information indicates an offset of the timing advance from the terminal to the target network device.
5 . The method according to claim 3 , wherein the handover message further comprises one or more of the second information and the resource information.
6 . The method according to claim 2 , wherein the first request message further comprises one or more of the following information: third information, fourth information, and fifth information, wherein
the third information indicates a distance between the source network device and a satellite;
the fourth information indicates a timing advance from the source network device to the satellite; and
the fifth information indicates a timing advance from the terminal to the satellite.
7 . The method according to claim 2 , wherein sending the first request message to the target network device comprises:
sending a second request message to a core network device to enable the core network device to send the first request message to the target network device based on the second request message; and
receiving the first acknowledgment message from the target network device comprises:
receiving a second acknowledgment message from the core network device, wherein the second acknowledgment message is sent by the core network device after the core network device receives the first acknowledgment message from the target network device.
8 . The method according to claim 1 , wherein the effective-time information indicates a jump time of the source cell or an appearance time of the target cell.
9 . The method according to claim 1 , wherein the method further comprises:
receiving capability information of the terminal indicating that the terminal supports a random access process-free handover mechanism or a handover complete message-free handover mechanism.
10 . A communication system comprising:
a source network device and a target network device, wherein:
the source network device being configured to send a first request message to the target network device for requesting a handover of a terminal to the target network device, the first request message comprising effective-time information of a handover configuration and first information indicating that the handover is for a satellite cell jump wherein a plurality of terminals, including the terminal, are handed over at a same time from a source cell of the source network device to the target cell of the target network device;
the source network device being further configured to send a handover message, to the terminal, for handing over the terminal from the source network device to the target network device, the handover message comprising the effective-time information and indication information indicating to perform a random access-free process or a handover complete message-free process in a handover process; and
the target network device being configured to receive the first request message.
11 . The communication system according to claim 10 , wherein the target network device is further configured to send a first acknowledgment message to the source network device, wherein the first acknowledgment message indicates that the terminal is allowed to be handed over to the target network device.
12 . The communication system according to claim 10 , wherein the effective-time information indicates a jump time of the source cell or an appearance time of the target cell.
13 . The communication system according to claim 10 , wherein the target network device is further configured to receive uplink data sent by the terminal, or feedback information sent by the terminal after the terminal receives downlink data from the target network device.
14 . The communication system according to claim 10 , wherein the target network device is further configured to
receive a second request message from a core network device, wherein the second request message is sent by the core network device after the core network device receives the first request message from the source network device; and
to send the first acknowledgment message to the core network device.
15 . A communication apparatus, comprising:
at least one processor and a transceiver, wherein the at least one processor is configured to implement program instructions in order to:
send, to a target network device, a first request message requesting a handover of a terminal to the target network device, the first request message comprising effective-time information of a handover configuration and first information indicating that the handover is for a satellite cell jump wherein a plurality of terminals, including the terminal, are handed over at a same time from a source cell of a source network device to a target cell of the target network device; and
send a handover message, to the terminal, for handing over the terminal from the source network device to the target network device, the first handover message comprising first indication information indicating to perform a random access-free process or a handover complete message-free process in a handover process.
16 . The communication apparatus according to claim 15 , wherein the at least one processor is configured to implement the program instructions in order to further:
receive a first acknowledgment message from the target network device indicating that the terminal is allowed to be handed over to the target network device.
17 . The communication apparatus according to claim 16 , wherein the first acknowledgment message comprises second information or first resource information, wherein
the second information is used by the terminal to determine a timing advance from the terminal to the target network device, and
the first resource information indicates an uplink time-frequency resource scheduled for the terminal.
18 . The communication apparatus according to claim 17 , wherein the second information indicates the timing advance from the terminal to the target network device, or the second information indicates an offset of the timing advance from the terminal to the target network device.
19 . The communication apparatus according to claim 15 , wherein the effective-time information indicates a jump time of the source cell or an appearance time of the target cell.