Method and apparatus for spectrum defragmentation, device, and system

A transmit end, comprising:

• a processor configured to adjust, on a first line, a frequency band for a target data stream from a to-be-adjusted frequency band to a target frequency band;
• and
• a transceiver coupled to the processor and configured to:
• obtain the target data stream carrying a sequence identifier of a data unit of the target data stream, wherein the sequence identifier indicates a transmission sequence of the data unit;
• send, on the first line, the target data stream using the to-be-adjusted frequency band;
• responsive to determining to defragment spectrum resources on the first line, switch transmission of the target data stream from the first line to a second line, wherein the first line and the second line are selected from a plurality of transmission lines available to the transmit end;
• use the first line or the second line to assist in spectrum defragmentation of a third line selected from the plurality of transmission lines;
• switch, after the processor adjusts the frequency band for the target data stream to the target frequency band, transmission of the target data stream from the second line to the first line by using the target frequency band to transmit the target data stream on the first line;
• record a sequence identifier X of a second data unit that is last sent on the second line when the target data stream is switched from the second line to the first line;
• and
• send, on the target frequency band of the first line, the target data stream starting from a third data unit whose sequence identifier is equal to X+1 using the target frequency band.

A receive end, comprising:

• a processor configured to adjust, on a first line, a frequency band for a target data stream from a to-be-adjusted frequency band to a target frequency band;
• and
• a transceiver coupled to the processor and configured to:
• receive, on the first line, the target data stream using the to-be-adjusted frequency band, wherein the target data stream carries a sequence identifier of a data unit of the target data stream, and wherein the sequence identifier indicates a transmission sequence of the data unit of the target data stream;
• switch reception of the target data stream from the first line to a second line after spectrum defragmentation is started, wherein the first line and the second line are selected from a plurality of transmission lines;
• use the first line or the second line to assist in spectrum defragmentation of a third line selected from the plurality of transmission lines;
• switch, after the processor adjusts the frequency band for the target data stream to the target frequency band, reception of the target data stream from the second line to the first line;
• record a sequence identifier X of a second data unit that is most recently received on the second line when the target data stream is switched from the second line to the first line;
• and
• receive, on the target frequency band of the first line, the target data stream starting from a third data unit whose sequence identifier is equal to X+1 using the target frequency band.