PROTOCOL SYNCHRONIZATION FOR HARQ BACKGROUND

• US 20130266001A1
• Filed: 06/18/2013
• Published: 10/10/2013
• Est. Priority Date: 10/09/2006
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Peisa, Janne, Meyer, Michael, Parkvall, Stefan, Stattin, Magnus, Sgfors, Mats, Torsner, Johan
• Granted Patent: US 9,485,059 B2
• Time in Patent Office: Days
• US Class Current: 370/350
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/1607 Details of the supervisory signal
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 69/324 in the data link layer [OSI layer 2], e.g. HDLC
• CPC Class Codes: H04L 7/0079 Receiver details
• CPC Class Codes: H04W 56/001 Synchronization between nodes

Abstract

A method and apparatus according to the present invention addresses and/or prevents lost protocol synchronization in HARQ systems caused by ACK/NACK errors. One embodiment detects lost synchronization errors for NDI-based retransmission protocols and restores synchronization by sending an explicit RESET message. In response to the RESET message, the transmitter aborts the transmission of a current PDU and transmits a new PDU and corresponding NDI. Another embodiment prevents protocol synchronization errors by sending scheduling grants on a packet by packet basis. The receiver sends a subsequent explicit scheduling grant to the transmitter based on an error evaluation of a received PDU. The transmitter will not send the next PDU unless it receives the subsequent explicit scheduling grant.

Claims

1. A method for improving link layer protocol synchronization between a transmitter and receiver in a wireless communication system, the method comprising:

transmitting a plurality of successive protocol data units from the transmitter to the receiver, each protocol data unit having a corresponding new data indicator to distinguish each succeeding protocol data unit from a preceding protocol data unit;

receiving a reset request from the receiver indicating that a protocol synchronization error has occurred; and

aborting transmission of a current protocol data unit responsive to said reset request and transmitting the succeeding protocol data unit to said receiver with the corresponding new data indicator to distinguish the succeeding protocol data unit from the aborted protocol data unit.

2. The method of claim 1 wherein each new data indicator comprises a single bit that toggles each time a new PDU is transmitted by the transmitter.

3. The method of claim 1 wherein each new data indicator comprises two or more bits that are set to a predetermined value each time a new PDU is transmitted by the transmitter.

4. A method for improving link layer protocol synchronization between a transmitter and receiver in a wireless communication system, the method comprising:

receiving a new data indicator and a corresponding protocol data unit at the receiver;

detecting a protocol synchronization error between the transmitter and the receiver based on the new data indicator; and

transmitting a reset message to the transmitter responsive to the detected protocol synchronization error to correct the protocol synchronization error between the transmitter and the receiver.

5. The method of claim 4 further comprising determining a type of the protocol synchronization error, wherein transmitting the reset message comprises transmitting the reset message when the protocol synchronization error comprises an unrecoverable protocol synchronization error.

6. The method of claim 5 further comprising correcting protocol settings at the receiver when the protocol synchronization error comprises a recoverable protocol synchronization error.

7. The method of claim 5 wherein determining the type of the protocol synchronization error comprises determining the type of the protocol synchronization error based on a soft combining of a current received protocol data unit and at least one previous received protocol data unit.

8. The method of claim 7 wherein the step of soft combining comprises soft combining the current received protocol data unit and the at least one previous received protocol data unit to determine whether the protocol synchronization error comprises a new data indicator error, an ACK error, or a NACK error.

9. The method of claim 8 wherein the new data indicator error and the ACK error comprise recoverable protocol synchronization errors, and wherein the NACK error comprises an unrecoverable protocol synchronization error.

10. A transmitter in communication with a remote receiver in a wireless communication system, the transmitter comprising a transmit processor configured to:

transmit a plurality of successive protocol data units from the transmitter to the receiver, each protocol data unit having a corresponding new data indicator to distinguish each succeeding protocol data unit from a preceding protocol data unit;

receive a reset request from the receiver indicating that a protocol synchronization error has occurred; and

abort transmission of a current protocol data unit responsive to said reset request and transmit the succeeding protocol data unit to said receiver with the corresponding new data indicator to distinguish the succeeding protocol data unit from the aborted protocol data unit.

11. The transmitter of claim 10 wherein each new data indicator comprises a single bit that toggles each time a new PDU is transmitted by the transmitter.

12. The transmitter of claim 10 wherein each new data indicator comprises two or more bits that are set to a predetermined value each time a new PDU is transmitted by the transmitter.

13. A receiver in communication with a remote transmitter in a wireless communication system, the receiver comprising a receive processor configured to:

receive a new data indicator and a corresponding protocol data unit at the receiver;

detect a protocol synchronization error between the receiver and the remote transmitter based on the new data indicator; and

transmit a reset message to the transmitter responsive to the detected protocol synchronization error to correct a protocol synchronization error between the transmitter and the receiver.

14. The receiver of claim 13 further comprising an error processor configured to determine a type of the protocol synchronization error, wherein the receive processor is configured to transmit the reset message by transmitting the reset message when the protocol synchronization error comprises an unrecoverable protocol synchronization error.

15. The receiver of claim 14 wherein the receive processor is further configured to correct protocol settings at the receiver when the protocol synchronization error comprises a recoverable protocol synchronization error.

16. The receiver of claim 14 wherein the error processor comprises a soft combiner to soft combine a current received protocol data unit and at least one previous received protocol data unit to determine the type of the protocol synchronization error.

17. The receiver of claim 16 wherein the soft combiner soft combines the current received protocol data unit and the at least one previous received protocol data unit to determine whether the protocol synchronization error comprises a new data indicator error, an ACK error, or a NACK error.

18. The receiver of claim 17 wherein the new data indicator error and the ACK error comprise recoverable protocol synchronization errors, and wherein the NACK error comprises an unrecoverable protocol synchronization error.