Link layer acknowledgement and retransmission for cellular telecommunications
First Claim
1. A mobile telecommunications system comprising:
- a mobile user equipment unit;
at least one node through which a packet switched data session is established between the user equipment until and a data network;
wherein one of the node and the user equipment unit servers as a transmitter of segments of data packets and the other of the node and the user equipment unit serves as a receiver of the segments of data packets; and
wherein the receiver, upon arrival of a segment which is sequenced to a first lost segment, detects loss of the first lost segment and, in response to the arrival and detection of the loss, sends a first acknowledgment message to the transmitter, and wherein if (1) the first lost segment is not received within a timed interval initiated in conjunction with detection of the loss of the loss of the first lost segment and (2) the receiver subsequently determines that a second lost segment has been lost during the timed interval, at expiration of the timed interval the receiver sends a second acknowledgment message to the transmitter, the second selective acknowledgment message indicating loss of both the first lost segment and the second lost segment.
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Accused Products
Abstract
A mobile telecommunications system comprises a mobile user equipment unit and at least one node through which a packet switched data session is established between the user equipment unit and a data network. One of the node and the user equipment unit serves as a transmitter of segments of data packets and the other of the node and the user equipment unit serves as a receiver of the segments of data packets. If the first lost segment is not received within a timed interval, and if a second lost segment is also lost during the timed interval, at expiration of the timed interval the receiver sends a selective acknowledgment message to the transmitter which requests retransmission of both the first lost segment and the second lost segment. The acknowledgment messages of the system have a unique format including start sequence number and a variable size bitmap field. The start sequence number (ssn) is mapped to a first non-received segment in a receive buffer; the first bit in the bitmap maps to a segment with a sequence number equal to the start sequence number. In differing embodiments, the bitmaps of the acknowledgment messages may have or may not have a stop bit. The transmitter has a poll timer that is started/restarted and canceled in accordance with novel timer operational rules.
156 Citations
32 Claims
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1. A mobile telecommunications system comprising:
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a mobile user equipment unit;
at least one node through which a packet switched data session is established between the user equipment until and a data network;
wherein one of the node and the user equipment unit servers as a transmitter of segments of data packets and the other of the node and the user equipment unit serves as a receiver of the segments of data packets; and
wherein the receiver, upon arrival of a segment which is sequenced to a first lost segment, detects loss of the first lost segment and, in response to the arrival and detection of the loss, sends a first acknowledgment message to the transmitter, and wherein if (1) the first lost segment is not received within a timed interval initiated in conjunction with detection of the loss of the loss of the first lost segment and (2) the receiver subsequently determines that a second lost segment has been lost during the timed interval, at expiration of the timed interval the receiver sends a second acknowledgment message to the transmitter, the second selective acknowledgment message indicating loss of both the first lost segment and the second lost segment. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
a buffer for storing segments to be transmitted to the receiver;
a poll timer, and wherein the poll timer is started/restarted when any of the following occur;
(1) a sequence number of a segment to be sent from the transmitter to the receiver is greater than or equal to V(a)+MaxWin−
MaxP, wherein V(a) is a sequence number of a first segment in a transmission window, MaxWin is the size of the transmission window, and MaxP is an integer less than MaxWin;
(2) one or more segments are to be retransmitted from the transmitter to the receiver if the poll timer is already running;
(3) a segment to be transmitted is a last segment in the buffer.
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9. The system of claim 8, wherein the integer MaxP is dynamically determined.
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10. The system of claim 8, wherein the integer MaxP depends on a number of consecutive lost acknowledgment messages allowed.
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11. The system of claim 10, wherein MaxP is determined by the following expression:
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12. The system of claim 8, wherein the integer MaxP depends on a frequency of negative acknowledgment messages.
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13. The system of claim 8, wherein a time out value for the poll timer is dynamically determined.
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14. The system of claim 8, wherein the poll timer is canceled if:
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(1) a segment to be transmitted is the last segment in the transmission buffer; and
(2) an acknowledgment message has been received which has a start sequence number field which is greater than the sequence number of the last transmitted segment.
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15. The system of claim 8, wherein the poll timer is canceled if:
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(1) a segment to be transmitted is not a last segment in the transmission buffer; and
any acknowledgment message is received which includes a start sequence number which is greater than the first segment (V(a)) in the transmission window.
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16. A method of operating a mobile telecommunications system comprising at least one node through which a packet switched data session is established between a user equipment unit and a data network, the method comprising:
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using one of the node and the user equipment unit to serve as a transmitter of segments of data packets and using the other of the node and the user equipment unit to serve as a receiver of the segments of data packets;
upon arrival of a segment which is sequenced subsequent to a first lost segment, detecting loss of the first lost segment;
in response to the arrival and detection of the loss, sending a first acknowledgment message from the receiver to the transmitter; and
when (1)the first lost segment is not received within a timed interval initiated in conjunction with the detection of the loss of the first lost segment and (2) a second lost segment is subsequently lost during the timed interval, the method further comprises sending from the receiver, at expiration of the timed interval, a second selective acknowledgment message to the transmitter, the second selective acknowledgment message indicating loss of both the first lost segment and the second lost segment. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
(1) a sequence number of a segment to be sent from the transmitter to the receiver is greater than or equal to V(a)+MaxWin−
MaxP, wherein V(a) is a sequence number of a first segment in a transmission window, MaxWin is the size of the transmission window, and MaxP is a predefined integer less than MaxWin;
(2) one or more segments are to be retransmitted from the transmitter to the receiver if the poll timer is already running;
(3) a segment to be transmitted is a last segment in the buffer.
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24. The method of claim 23, wherein the integer MaxP is dynamically determined.
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25. The method of claim 23, wherein the integer MaxP depends on a number of consecutive lost acknowledgment messages allowed.
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26. The method of claim 25, wherein MaxP is determined by the following expression:
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27. The method of claim 23, wherein the integer MaxP depends on a frequency of negative acknowledgment messages.
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28. The method of claim 23, wherein a time out value for the poll timer is dynamically determined.
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29. The method of claim 23, further comprising canceling the poll timer if:
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(1) a segment to be transmitted is the last segment in the transmission buffer; and
(2) an acknowledgment message has been received which has a start sequence number field which is greater than the sequence number of the last transmitted segment.
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30. The method of claim 23, further comprising canceling the poll timer if:
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(1) a segment to be transmitted is not a last segment in the transmission buffer; and
(2) any acknowledgment message is received which includes a start sequence number which is greater than the first segment (V(a)) in the transmission window.
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31. A mobile telecommunications system comprising a node through which a packet switched data session is established with a user equipment unit, wherein the node serves as a receiver of segments of data packets, and
wherein the receiver, upon arrival of a segment which is sequenced subsequent to a first lost segment, detects loss of the first lost segment and, in response to the arrival and detection of the loss, sends a first acknowledgment message to the transmitter, and wherein if (1) the first lost segment is not received within a timed interval initiated in conjunction with detection of the loss of the first lost segment and (2) the receiver subsequently determines that a second lost segment has been lost during the timed interval, at expiration of the timed interval the receiver sends a second acknowledgment message to the transmitter, the second selective acknowledgment message indicating loss of both the first lost segment and the second lost segment.
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32. A mobile user equipment unit which serves as a receiver of segments of data packets in a packet switched data session, and
wherein the receiver, upon arrival of a segment which is sequenced subsequent to a first lost segment, detects loss of the first lost segment and, in response to the arrival and detection of the loss, sends a first acknowledgment message to the transmitter, and wherein if (1) the first segment is not received within a timed interval initiated in conjunction with detection of the loss of the first lost segment and (2) the receiver subsequently determines that a second lost segment has been lost during the timed interval, at expiration of the timed interval the receiver sends a second acknowledgment message to the transmitter, the second selective acknowledgment message indicating loss of both the first lost segment and the second lost segment.
Specification