System and method for implementing a semi reliable retransmission protocol
DC CAFC
First Claim
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1. A telecommunications system for transmitting data packets using a semi-reliable retransmission protocol that utilizes selective repeat automatic repeat request, comprising:
- a transmitter having a data link layer therein for receiving a service data unit containing a plurality of said data packets, said data link layer segmenting said service data unit into at least one protocol data unit;
a discard timer within said transmitter for monitoring a retransmission time of said at least one protocol data unit, said discard timer being initialized when said service data unit is received by said data link layer; and
a receiver for receiving said at least one protocol data unit from said transmitter over an air interface and transmitting an acknowledgment message to said transmitter over said air interface after determining that said at least one protocol data unit is received correctly, said service data unit being discarded by said transmitter and said receiver when said acknowledgment message is not transmitted for said at least one protocol data unit and said discard timer expires.
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Abstract
A telecommunications system and method is disclosed for implementing a semi-reliable retransmission protocol that utilizes both selective repeat Automatic Repeat Request (ARQ) and segmentation and assembly of data packets. The new semi-reliable retransmission protocol includes a timer based triggering of a retransmission timeout for retransmission protocols, which allows the retransmission timeout to become insensitive to variations in the channel rate. In addition, the retransmission timeout can be defined based upon the maximum delay allowable for the retransmission of corrupted data packets over the air interface. For every data packet received a timer monitoring the transmission time of the data packet is initialized. If the timer elapses for the data packet this data packet is marked as discarded in the transmitter, and a request is sent to the receiver to ensure that transmissions carrying that data packet are discarded in the receiver.
138 Citations
37 Claims
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1. A telecommunications system for transmitting data packets using a semi-reliable retransmission protocol that utilizes selective repeat automatic repeat request, comprising:
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a transmitter having a data link layer therein for receiving a service data unit containing a plurality of said data packets, said data link layer segmenting said service data unit into at least one protocol data unit;
a discard timer within said transmitter for monitoring a retransmission time of said at least one protocol data unit, said discard timer being initialized when said service data unit is received by said data link layer; and
a receiver for receiving said at least one protocol data unit from said transmitter over an air interface and transmitting an acknowledgment message to said transmitter over said air interface after determining that said at least one protocol data unit is received correctly, said service data unit being discarded by said transmitter and said receiver when said acknowledgment message is not transmitted for said at least one protocol data unit and said discard timer expires. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
a network layer for transmitting said service data unit to said data link layer; and
a physical layer for receiving said at least one protocol data unit from said data link layer and transmitting said at least one protocol data unit to said receiver over said air interface.
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3. The telecommunications system of claim 1, wherein said receiver further comprises:
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a physical layer for receiving said at least one protocol data unit from said transmitter over said air interface;
a data link layer for receiving said at least one protocol data unit from said physical layer, transmitting said acknowledgment message for each said at least one protocol data unit that is received correctly, and assembling said at least one protocol data unit back into said service data unit; and
a network layer for receiving said service data unit from said data link layer.
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4. The telecommunications system of claim 1, wherein said transmitter further comprises:
a transmit buffer for storing said at least one protocol data unit until said acknowledgment message is received for each said at least one protocol data unit or until said discard timer expires.
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5. The telecommunications system of claim 1, wherein said transmitter further comprises:
means for transmitting a “
move receiving window”
request message to said receiver when said discard timer expires and said acknowledgment message for each said at least one protocol data unit has not been received.
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6. The telecommunications system of claim 5, wherein said receiver further comprises:
a receiver buffer for storing said at least one protocol data unit, said at least one protocol data unit being removed from said receiver buffer when said “
move receiving window”
request message is received.
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7. The telecommunications system of claim 6, wherein said transmitter further comprises:
a receive timer for monitoring a reception time of said “
move receiving window”
request message, said receive timer being initialized when said “
move receiving window”
request message is transmitted by said transmitter, said transmitter retransmitting said “
move receiving window”
request message to said receiver if said receiver timer expires and a “
move receiving window”
acknowledgment message has not been received by said transmitter.
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8. The telecommunications system of claim 1, wherein said service data unit has a header associated therewith, said header having a dedicated field therein for storing a default value for said discard timer.
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9. The telecommunications system of claim 8, wherein said default value is based on a maximum retransmission delay allowable for data within said data packets.
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10. The telecommunications system of claim 1, further comprising:
an interval timer within said transmitter for monitoring a time interval between an arrival time of said service data unit at said data link layer and an arrival time of a successive service data unit at said data link layer, said interval timer being first initialized when said service data unit is received by said data link layer, said successive service data unit being time stamped with the current value of said interval timer when said successive service data unit is received by said data link layer and said discard timer has not expired.
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11. A transmitter for transmitting data packets over an air interface to a receiver using a semi-reliable retransmission protocol that utilizes selective repeat automatic repeat request, comprising:
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a data link layer for receiving a service data unit containing a plurality of said data packets, said data link layer segmenting said service data unit into at least one protocol data unit; and
a discard timer for monitoring the retransmission time of said at least one protocol data unit to said. receiver, said discard timer being initialized when said service data unit is received by said data link layer, said service data unit being discarded by said data link layer when an acknowledgment message is not received for each said at least one protocol data unit and said discard timer expires. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
a network layer for transmitting said service data unit to said data link layer; and
a physical layer for receiving said at least one protocol data unit from said data link layer and transmitting said at least one protocol data unit to a receiver over said air interface.
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13. The transmitter of claim 11, further comprising:
a transmit buffer for storing said at least one protocol data unit until said acknowledgment message is received for each said at least one protocol data unit or until said discard timer expires.
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14. The transmitter of claim 11, further comprising:
means for transmitting a “
move receiving window”
request message to a receiver when said discard timer expires and said acknowledgment message for each said at least one protocol data unit has not been received.
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15. The transmitter of claim 14, further comprising:
a receive timer for monitoring a reception time of said “
move receiving window”
request message, said receive timer being initialized when said “
move receiving window”
request message is transmitted by said transmitter, said transmitter retransmitting said “
move receiving window”
request message if said receiver timer expires and a “
move receiving window”
acknowledgment message has not been received by said transmitter.
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16. The transmitter of claim 11, wherein said service data unit has a header associated therewith, said header including a dedicated field for storing a default value for said discard timer.
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17. The transmitter of claim 16, wherein said default value is based on a maximum retransmission delay allowable for data within said data packets.
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18. The transmitter of claim 11, further comprising:
an interval timer for monitoring the time interval between an arrival time of said service data unit at said data link layer and an arrival time of a successive service data unit at said data link layer, said interval timer being initialized when said service data unit is received by said data link layer, said successive service data unit being time stamped with the current value of said interval timer when said successive service data unit is received by said data link layer and said discard timer has not expired.
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19. A method for transmitting data packets from a transmitter to a receiver over an air interface using a semi-reliable retransmission protocol that utilizes selective repeat automatic repeat request, comprising the steps of:
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receiving, by a data link layer within said transmitter, a service data unit containing a plurality of said data packets;
segmenting, by said data link layer, said service data unit into at least one protocol data unit;
initializing a discard timer within said transmitter when said service data unit is received by said data link layer;
transmitting said at least one protocol data unit from said transmitter over said air interface to said receiver;
transmitting an acknowledgment message from said receiver to said transmitter over said air interface after determining that said at least one protocol data unit is received correctly; and
discarding said service data unit by said transmitter and said receiver when said acknowledgment message is not transmitted for said at least one protocol data unit and said discard timer expires. - View Dependent Claims (20, 21, 22, 23, 24, 25)
storing, in a transmit buffer within said transmitter, said at least one protocol data unit until said acknowledgment message is received for each said at least one protocol data unit or until said discard timer expires.
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21. The method of claim 19, wherein said step of discarding further comprises the step of:
transmitting a “
move receiving window”
request message from said transmitter to said receiver when said discard timer expires and said acknowledgment message for each said at least one protocol data unit has not been received.
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22. The method of claim 21, wherein said step of discarding further comprises the step of:
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storing, within a receiver buffer within said receiver, said at least one protocol data unit; and
removing said at least one protocol data unit from said receiver buffer when said “
move receiving window”
request message is received.
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23. The method of claim 22, wherein said step of discarding further comprises the steps of:
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initializing a receive timer when said “
move receiving window”
request message is transmitted by said transmitter; and
retransmitting said “
move receiving window”
request message to said receiver if said receiver timer expires and a “
move receiving window”
acknowledgment message has not been received by said transmitter.
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24. The method of claim 19, further comprising the steps of:
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initializing an interval timer when said service data unit is received by said data link layer;
receiving a successive service data unit by said data link layer; and
appending a time stamp to said successive service data unit received by said data link layer, said time stamp being the current value of said interval timer when said discard timer has not expired.
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25. The method of claim 24, further comprising the steps of:
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stopping said discard timer when said acknowledgment message for each of said at least two protocol data units associated with said service data unit are received by said transmitter or when said discard timer expires; and
reinitializing said discard timer for said successive service data unit with a value of said time stamp.
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26. A receiver for receiving data packets over an air interface from a transmitter using a semi-reliable retransmission protocol that utilizes a selective repeat automatic repeat request technique, comprising:
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means for receiving at least one protocol data unit segmented from a service data unit containing a plurality of said data packets from said transmitter over said air interface;
means for transmitting an acknowledgment message to said transmitter over said air interface after determining that said at least one protocol data unit is received correctly;
means for requesting retransmission of each said at least one protocol data unit that is received incorrectly using said selective repeat automatic repeat request technique;
means for receiving a discard message from said transmitter when a discard timer monitoring the retransmission time of said at least one protocol data unit expires prior to the transmission of said acknowledgment message; and
means for discarding said service data unit upon receipt of said discard message. - View Dependent Claims (27, 28, 29)
a receive buffer for storing said at least one protocol data unit, said at least one protocol data unit being removed from said receive buffer upon receipt of said discard message.
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28. The receiver of claim 26, wherein said service data unit has a header associated therewith, said header having a dedicated field therein for storing a default value for said discard timer.
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29. The receiver of claim 28, wherein said default value is based on a maximum retransmission delay allowable for data within said data packets.
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30. A method for transmitting data packets over an air interface to a receiver using a semi-reliable retransmission protocol that utilizes selective repeat automatic repeat request, comprising:
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segmenting a service data unit containing a plurality of said data packets into at least one protocol data unit;
initializing a discard timer for monitoring the retransmission time of said at least one protocol data unit to said receiver;
transmitting said at least one protocol data unit from said transmitter to said receiver over said air interface; and
discarding said service data unit when an acknowledgment message is not received for each said at least one protocol data unit prior to the expiration of said discard timer. - View Dependent Claims (31, 32, 33, 34, 35)
storing, in a transmit buffer within said transmitter, each said at least one protocol data unit until said acknowledgment message is received for each said at least one protocol unit or until said discard timer expires.
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32. The method of claim 30, wherein said step of discarding further comprises the step of:
transmitting a discard message from said transmitter to said receiver upon expiration of said discard timer.
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33. The method of claim 32, wherein said step of discarding further comprises the steps of:
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initializing a receive timer upon transmission of said discard message; and
retransmitting said discard message to said receiver if said receiver timer expires prior to receipt of a discard acknowledgment message from said receiver.
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34. The method of claim 30, further comprising the steps of:
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initializing an interval timer upon receipt of said service data unit by a data link layer within said transmitter;
receiving a successive service data unit by said data link layer; and
appending a time stamp to said successive service data unit received by said data link layer, said time stamp being the current value of said interval timer when said discard timer has not expired.
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35. The method of claim 34, further comprising the steps of:
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stopping said discard timer when said acknowledgment message for each said at least one protocol data unit associated with said service data unit is received by said transmitter or when said discard timer expires; and
reinitializing said discard timer for said successive service data unit with a value of said time stamp.
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36. A method for receiving data packets over an air interface from a transmitter using a semi-reliable retransmission protocol that utilizes a selective repeat automatic repeat request technique, comprising the steps of
receiving at least one protocol data unit segmented from a service data unit containing a plurality of said data packets from said transmitter over said air interface; -
transmitting an acknowledgment message to said transmitter over said air interface after determining that said at least one protocol data unit is received correctly;
requesting retransmission of each said at least one protocol data unit that is received incorrectly using said selective repeat automatic repeat request technique;
receiving a discard message from said transmitter when a discard timer monitoring the retransmission time of said at least one protocol data unit expires prior to the transmission of said acknowledgment message; and
discarding said service data unit upon receipt of said discard message. - View Dependent Claims (37)
storing, within a receive buffer within said receiver, said at least one protocol data unit, said at least one protocol data unit being removed from said receive buffer upon receipt of said discard message.
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Specification
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Litigation Data
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Current AssigneeWi-Fi One, LLC (Inception Holdings, LLC)
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Original AssigneeTelefonaktiebolaget LM Ericsson
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InventorsWager, Stefan Henrik Andreas, Ludwig, Reiner
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Primary Examiner(s)VANDERPUYE, KENNETH N
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Application NumberUS09/287,392Time in Patent Office1,407 DaysField of Search370/469, 370/389, 370/395, 370/278, 370/216, 714/748, 714/749, 714/750US Class Current370/216CPC Class CodesH04L 1/1809 Selective-repeat protocolsH04L 1/1812 Hybrid protocols; Hybrid au...H04L 1/1877 for semi-reliable protocols...H04L 1/188 Time-out mechanisms
