NR RLC segment concatenation
Transmitters consider the size of a gap segment adjacent to at least one negatively acknowledged (NACKed) Radio Link Control (RLC) Service Data Unit (SDU) when considering when and/or how to concatenate one or more NACKed SDU segments for retransmission. Depending on which RLC SDU segment(s) is/are NACKed, e.g., considering the size of NACKed segments in relation to Protocol Data Unit (PDU) header size(s) needed, the transmitter implements a single RLC SDU retransmission or multiple RLC SDU segment retransmissions. In so doing, the solution presented herein not only defines how such transmissions occur, but also provides improved efficiency when retransmitting such NACKed SDU segments.
1. A method performed by a transmitter for transmitting a Radio Link Protocol (RLC) Service Data Unit (SDU) to a receiver in wireless communication with the transmitter, the method comprising:
transmitting a plurality of segments to the receiver, each of said segments comprising one or more bytes of the SDU;
receiving at least one NACK from the receiver identifying a corresponding negatively acknowledged segment, wherein each negatively acknowledged segment comprises one of the plurality of transmitted segments for which the transmitter received the NACK;
identifying a gap segment adjacent to at least one of the negatively acknowledged segments, said gap segment comprising at least one non-negatively acknowledged segment;
generating at least one retransmission packet responsive to a size of the gap segment, each of the at least one retransmission packets comprising a header and at least one of the negatively acknowledged segments; and
transmitting the at least one retransmission packet to the receiver.
2. The method of claim 1 wherein said receiving the at least one NACK comprises:
receiving a first NACK identifying a first negatively acknowledged segment for the SDU; and
receiving a second NACK identifying a second negatively acknowledged segment for the SDU;
wherein the first and second negatively acknowledged segments are adjacent to, and spaced within the SDU by, the gap segment.
3. The method of claim 2 wherein said generating the at least one retransmission packet comprises generating a retransmission packet comprising the header, the gap segment, and the first and second negatively acknowledged segments when a size of the header exceeds the size of the gap segment.
4. The method of claim 2 further comprising reducing a size of the header by an offset to determine a reduced header with a reduced header size, wherein said generating the at least one retransmission packet comprises generating a retransmission packet comprising the reduced header, the gap segment, and the first and second negatively acknowledged segments when the reduced header size exceeds the size of the gap segment.
5. The method of claim 2 wherein:
the first negatively acknowledged segment corresponds to a first segment of the SDU and the second negatively acknowledged segment corresponds to any other segment of the SDU;
a first header associated with a retransmission of the first negatively acknowledged segment has a first header size and a second header associated with a separate retransmission of the second negatively acknowledged segment has a second header size larger than the first header size; and
said generating the at least one retransmission packet comprises generating a retransmission packet comprising the first header, the gap segment, and the first and second negatively acknowledged segments when the second header size exceeds the size of the gap segment.
6. The method of claim 1 wherein said receiving the at least one NACK comprises:
receiving a first NACK identifying a first negatively acknowledged segment of the SDU;
receiving a second NACK identifying a second negatively acknowledged segment of the SDU adjacent to the first negatively acknowledged segment and adjacent to the gap segment; and
receiving a third NACK identifying a third negatively acknowledged segment of the SDU adjacent to the gap segment;
wherein the second and third negatively acknowledged segments are spaced within the SDU by the gap segment.
7. The method of claim 6 wherein said generating the at least one retransmission packet comprises:
generating a retransmission packet comprising the header, the gap segment, and the first, second, and third negatively acknowledged segments when a size of the header exceeds the size of the gap segment; and
generating first and second retransmission packets when the size of the gap segment exceeds the size of the header, said first retransmission packet comprising the header and the first and second negatively acknowledged segments and said second retransmission packet comprising the header and the third negatively acknowledged segment.
8. The method of claim 6 wherein:
the first negatively acknowledged segment corresponds to a first segment of the SDU, the second negatively acknowledged segment corresponds to a second segment of the SDU, and the third negatively acknowledged segment corresponds to any other segment of the SDU;
a first header associated with a retransmission of the first negatively acknowledged segment has a first header size and a second header associated with a separate retransmission of the second or third negatively acknowledged segments has a second header size larger than the first header size; and
said generating the at least one retransmission packet comprises:
generating a retransmission packet comprising the first header, the gap segment, and the first, second, and third negatively acknowledged segments when the second header size exceeds the size of the gap segment; and
generating first and second retransmission packets when the size of the gap segment exceeds the second header size, said first retransmission packet comprising the first header and the first and second negatively acknowledged segments and said second retransmission packet comprising the second header and the third negatively acknowledged segment.
9. The method of claim 1 wherein the gap segment is between the negatively acknowledged segment and the end of the SDU.
10. The method of claim 9 wherein:
the gap segment comprises at least one segment that has not yet been acknowledged or negatively acknowledged;
the transmitter anticipates that the at least one segment in the gap segment that has not yet been acknowledged or negatively acknowledged will be negatively acknowledged; and
said generating the at least one retransmission packet further comprises generating the at least one retransmission packet comprising the header, the gap segment, and the at least one of the negatively acknowledged segments responsive to the anticipation.
11. The method of claim 1 wherein the gap segment includes a first segment of the SDU and wherein each negatively acknowledged segment comprises one of the plurality of segments following the first segment of the SDU.
12. The method of claim 11 wherein a first header associated with a retransmission including the first segment has a first header size and a second header associated with a separate retransmission that does not include the first segment has a second header size larger than the first header size, and wherein said generating the at least one retransmission packet comprises:
generating a retransmission packet comprising the first header, the gap segment, and one or more of the negatively acknowledged segments when the second header size exceeds the size of the gap segment; and
generating a retransmission packet comprising the second header and one or more of the negatively acknowledged segments when the size of the gap segment exceeds the second header size.
13. The method of claim 1 wherein said generating the at least one retransmission packet comprises generating a retransmission packet comprising two or more negatively acknowledged segments when a size of the header exceeds the size of the gap segment, wherein two of the two or more negatively acknowledged segments are adjacent to and separated by the gap segment.
14. The method of claim 1 wherein each of the at least one non-negatively acknowledged segments of the gap segment comprises a not yet transmitted segment of the SDU, an already acknowledged segment of the SDU, or a transmitted segment of the SDU that has not yet been acknowledged or negatively acknowledged.
15. The method of claim 1 wherein:
the gap segment comprises at least one segment that has not yet been acknowledged or negatively acknowledged;
the transmitter anticipates that the at least one segment in the gap segment that has not yet been acknowledged or negatively acknowledged will be negatively acknowledged; and
said generating the at least one retransmission packet further comprises generating the at least one retransmission packet comprising the header, the gap segment, and the at least one of the negatively acknowledged segments responsive to the anticipation.
16. The method of claim 1 wherein the transmitter is comprised in a wireless device or is comprised in a network node.
17. A transmitter in wireless communication with a receiver, the transmitter comprising processing circuitry configured to:
transmit a plurality of segments to the receiver, each of said segments comprising one or more bytes of a Service Data Unit (SDU);
receive at least one NACK from the receiver identifying a corresponding negatively acknowledged segment, wherein each negatively acknowledged segment comprises one of the plurality of transmitted segments for which the transmitter received the NACK;
identify a gap segment adjacent to at least one of the negatively acknowledged segments, said gap segment comprising at least one non-negatively acknowledged segment;
generate at least one retransmission packet responsive to a size of the gap segment, each of the at least one retransmission packets comprising a header and at least one of the negatively acknowledged segments; and
transmit the at least one retransmission packet to the receiver.
18. The transmitter of claim 17 wherein the transmitter is comprised in a wireless device or is comprised in a network node.
19. The transmitter of claim 17 wherein the transmitter is comprised in a network node.
20. A non-transitory computer-readable medium storing a computer program product for controlling a wireless transmitter, the computer program product comprising software instructions which, when run on at least one processing circuit in the wireless transmitter, causes the wireless transmitter to:
transmit a plurality of segments to a receiver, each of said segments comprising one or more bytes of a Service Data Unit (SDU);
receive at least one NACK from the receiver identifying a corresponding negatively acknowledged segment, wherein each negatively acknowledged segment comprises one of the plurality of transmitted segments for which the transmitter received the NACK;
identify a gap segment adjacent to at least one of the negatively acknowledged segments, said gap segment comprising at least one non-negatively acknowledged segment;
generate at least one retransmission packet responsive to a size of the gap segment, each of the at least one retransmission packets comprising a header and at least one of the negatively acknowledged segments; and
transmit the at least one retransmission packet to the receiver.