Retransmission In Wireless Communication Systems

• US 20080089314A1
• Filed: 12/17/2004
• Published: 04/17/2008
• Est. Priority Date: 12/17/2004
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Ludwig, Reiner, Meyer, Michael
• Granted Patent: US 8,050,248 B2
• Time in Patent Office: Days
• US Class Current: 370/349
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/26 using explicit feedback to the source, e.g. choke packets
• CPC Class Codes: H04W 28/02 Traffic management, e.g. flow control or congestion control
• CPC Class Codes: H04W 8/04 Registration at HLR or HSS [Home Subscriber Server]

Abstract

The invention relates to retransmissions in wireless communication systems. It is proposed to reduce the retransmission delays by utilizing feedback associated with a lower protocol layer than the conventional feedback messages of the ARQ functionality. After sending a packet from a transmitter towards a receiver, the transmitter monitors the link for a low-level control signal from the receiver. The low-level control information can e.g. comprise power control commands or be related to link quality indicators. Based on this signal, it is decided whether a retransmission is to take place, e.g. at the transmitter or at an external control unit.

Claims

1. A method for reducing retransmission delays in a wireless communication system with Automatic Repeat reQuest (ARQ) retransmission functionality, comprising the steps of:

sending a protocol data unit (PDU) from a transmitting side towards a receiving side;

monitoring, at the transmitting side, a low-level control signal from the receiving side, the low-level control signal being associated with a lower protocol layer than the layer of the ARQ retransmission functionality; and

deciding whether a retransmission of the PDU is to take place based on the low-level control signal.

2. The method of claim 1, wherein the low-level control signal comprises feedback being faster or more frequent than explicit feedback of the ARQ retransmission functionality and reflecting the transmission status of the PDU at the receiving side.

3. The method of claim 1, wherein the monitoring and deciding steps are performed while the transmitting side is in a waiting state with regard to the explicit feedback of the ARQ retransmission functionality.

4. The method of claim 1, wherein the ARQ retransmission functionality belongs to a data link layer and the low-level control signal is associated with a physical layer.

5. The method of claim 4, wherein the ARQ retransmission functionality comprises layer two ARQ feedback and the low-level control signal comprises layer one feedback.

6. The method of claim 1, wherein the low-level control signal is a power control command.

7. The method of claim 6, wherein the deciding step in turn comprises determining the number of power up commands from the receiving side for a predetermined period of time, whereby a high number of power up commands is an indication for retransmission.

8. The method of claim 1, wherein the low-level control signal is a link quality indicator.

9. The method of claim 8, wherein the link quality indicator relates to at least one of modulation mode;

coding rate;

signal-to-noise ratio; and

carrier-to-interference ratio.

10. The method of claim 1, further comprising the step of retransmitting the PDU from the transmitting side towards the receiving side in accordance with the deciding step and without having received an ARQ response message for the PDU.

11. The method of claim 1, further comprising the step of determining the amount of retransmission data based on characteristics of the low-level control signal.

12. The method of claim 1, in a single-hop scenario, comprising the steps of:

sending the PDU from a transmitting node on the transmitting side towards a receiving node at the receiving side;

monitoring, at the transmitting node, the low-level control signal from the receiving node; and

deciding, at the transmitting node, whether a retransmission of the PDU is to take place based on the low-level control signal.

13. The method of claim 1, in an uplink scenario, comprising the steps of:

sending the PDU from a terminal on the transmitting side towards a first communication node on the receiving side, said first communication node including ARQ functionality;

monitoring, at the terminal, the low-level control signal from a second communication node on the receiving side; and

deciding, at the terminal, whether a retransmission of the PDU is to take place based on the low-level control signal.

14. The method of claim 1, in a downlink scenario, comprising the steps of:

sending the PDU from a first communication node on the transmitting side towards a terminal on the receiving side said first communication node including ARQ functionality;

monitoring, at a second communication node on the transmitting side, the low-level control signal from the terminal;

communicating a recommendation on retransmission of the PDU together with an identifier for the PDU from the second communication node to the first communication node; and

deciding, at the first communication node, whether a retransmission is to take place based on the retransmission recommendation.

15. A wireless communication system with ARQ retransmission functionality and means for reducing retransmission delays, comprising:

means for sending a PDU from a transmitting side towards a receiving side;

means for monitoring, at the transmitting side, a low-level control signal from the receiving side, the low-level control signal being associated with a lower protocol layer than the layer of the ARQ retransmission functionality; and

means for deciding whether a retransmission is to take place based on the low-level control signal.

16. The system of claim 15, wherein the low-level control signal comprises feedback being faster or more frequent than the explicit feedback of the ARQ retransmission functionality and reflecting the transmission status of the PDU at the receiving side.

17. The system of claim 15 comprising means for running the monitoring means and the deciding means while the transmitting side is in a waiting state with regard to explicit feedback of the ARQ retransmission functionality.

18. The system of claim 15, wherein the ARQ retransmission functionality belongs to a data link layer and the low-level control signal is associated with a physical layer.

19. The system of claim 15, wherein the low-level control signal is a power control command.

20. The system of claim 15, wherein the low-level control signal is a link quality indicator.

21. The system of claim 15, further comprising means for retransmitting the PDU from the transmitting side towards the receiving side in accordance with the decision by the deciding means and without having received an ARQ response message.

22. The system of claim 15, comprising:

means for sending the PDU from a terminal on the transmitting side towards a first communication node on the receiving side, said first communication node including ARQ functionality;

means for monitoring, at the terminal, the low-level control signal from a second communication node on the receiving side; and

means for deciding, at the terminal, whether a retransmission of the PDU is to take place based on the low-level control signal.

23. The system of claim 15, comprising:

means for sending the PDU from a first communication node on the transmitting side towards a terminal on the receiving side said first communication node including ARQ functionality;

means for monitoring, at a second communication node on the transmitting side, the low-level control signal from the terminal;

means for communicating a recommendation on retransmission of the PDU together with an identifier for the PDU from the second communication node to the first communication node; and

means for deciding, at the first communication node, whether retransmission is to take place based on the retransmission recommendation.

24. A communication unit with means for reducing retransmission delays arranged at a transmitting side in a wireless communication system with ARQ retransmission functionality, comprising:

means for monitoring a low-level control signal from a receiving side upon transmission of a PDU from the transmitting side towards the receiving side, the low-level control signal being associated with a lower protocol layer than the layer of the ARQ retransmission functionality; and

means for performing a retransmission decision based on the low-level control signal.

25. The communication unit of claim 24, comprising:

means for sending the PDU towards the receiving side;

means for deciding whether a retransmission is to take place based on the low-level control signal; and

means for retransmitting the PDU towards the receiving side in accordance with the decision by the deciding means and without having received an ARQ response message for the PDU.

26. The communication unit of claim 24, comprising:

means for deciding whether a retransmission is to be recommended based on the low-level control signal; and

means for communicating a recommendation on retransmission of the PDU together with an identifier for the PDU to another communication unit at the transmitting side, the other communication unit including ARQ retransmission functionality.

27. The communication unit of claim 24, wherein the low-level control signal comprises feedback being faster or more frequent than explicit feedback of the ARQ retransmission functionality and reflecting the transmission status of the PDU at the receiving side.

28. The communication unit of claim 25, comprising means for running the monitoring means and the deciding means while the transmitting side is in a waiting state with regard to explicit feedback of the ARQ retransmission functionality.

29. The communication unit of claim 24, wherein the ARQ retransmission functionality belongs to a data link layer and the low-level control signal is associated with a physical layer.

30. The communication unit of claim 24, wherein the low-level control signal is a power control command.

31. The communication unit of claim 24, wherein the low-level control signal is a link quality indicator.

32. The communication unit of claim 24, comprising means for determining the amount of retransmission data based on characteristics of the low-level control signal.

33. A communication unit with ARQ retransmission functionality and means for reducing retransmission delays arranged at a transmitting side in a wireless communication system, comprising:

means for sending a PDU towards a receiving side of the wireless communication system;

means for receiving a recommendation on retransmission of the PDU together with an identifier for the PDU from another communication node at the transmitting side; and

means for deciding whether retransmission is to take place based on the retransmission recommendation.

34. The communication unit of claim 33, further comprising means for retransmitting the PDU towards the receiving side in accordance with the decision by the deciding means and without having received an ARQ response message for the PDU.

35. The communication unit of claim 33, wherein the low-level control signal comprises feedback being faster or more frequent than explicit feedback of the ARQ retransmission functionality and reflecting the transmission status of the PDU at the receiving side.

36. The communication unit of claim 33, wherein the ARQ retransmission functionality belongs to a data link layer and the low-level control signal is associated with a physical layer.

37. The communication unit of claim 33, wherein the low-level control signal is a power control command.

38. The communication unit of claim 33, wherein the low-level control signal is a link quality indicator.