Bandwidth efficient HARQ scheme in relay network

• US 20070190933A1
• Filed: 01/17/2007
• Published: 08/16/2007
• Est. Priority Date: 01/17/2006
• Status: Active Grant

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Zheng, Haihong, Saifullah, Yousuf, Swami, Yogesh, Zhang, JianZhong
• Granted Patent: US 8,149,757 B2
• Time in Patent Office: Days
• US Class Current: 455/7
• CPC Class Codes: H04B 7/15557 Selecting relay station operation mode, e.g. between amplify and forward mode, decode and forward mode or FDD - and TDD mode
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1867 Arrangements specially adapted for the transmitter end
• CPC Class Codes: H04L 2001/0092 Error control systems characterised by the topology of the transmission link
• CPC Class Codes: H04L 2001/0097 Relays

Abstract

The present invention provides an enhanced H-ARQ scheme that optimizes bandwidth utilization and spectrum efficiency. When an H-ARQ attempt is unsuccessful due to loss or error over a hop between the BS and MS/SS, then only the first node in the hop chain that fails to decode the packet transmits another H-ARQ attempt. The BS determines the first node that fails on decoding based on certain information such as the feedback information sent from the nodes on the path. The previous node of the failed node is then instructed to retransmit by the BS.

Claims

1. A method comprising:

sending an attempt from a base station to at least one relay station;

receiving an acknowledgement from a mobile station when the attempt is successfully decoded by the at least one relay station, and forwarded from the at least one relay station to the mobile station; and

when the attempt is not successfully decoded, identifying a first relay station which did not successfully receive and decode the attempt, and instructing a previous relay station to generate and send the attempt that was not successfully decoded.

2. The method of claim 1, wherein the sending of the attempt comprises sending a hybrid automatic repeat request attempt.

3. The method of claim 2, wherein the sending of the attempt comprises sending a packet.

4. The method of claim 1, further comprising receiving, at the base station, feedback information from the at least one relay station.

5. The method of claim 4, further comprising identifying, at the base station, the first relay station which did not successfully receive and decode the attempt based on certain information.

6. The method of claim 5, wherein the certain information comprises the feedback information received from the at least one relay station.

7. The method of claim 4, wherein the feedback information comprises an acknowledgment (ACK) or non-acknowledgment (NAK).

8. A method comprising:

sending an attempt from a mobile station to at least one relay station;

receiving an acknowledgement from a base station when the attempt is successfully decoded by the at least one relay station, and forwarded from the at least one relay station to the base station; and

when the attempt is not successfully decoded, identifying a first relay station which did not successfully receive and decode the attempt, and instructing a previous relay station to generate and send the attempt that was not successfully decoded.

9. The method of claim 8, wherein the sending of the attempt comprises sending a hybrid automatic repeat request attempt.

10. The method of claim 8, wherein the sending of the attempt comprises sending a packet.

11. The method of claim 8, further comprising receiving feedback information from the at least one relay station.

12. The method of claim 11, further comprising identifying the first relay station which did not successfully receive and decode the attempt based on certain information.

13. The method of claim 12, wherein the certain information comprises the feedback information received from the at least one relay station.

14. The method of claim 8, wherein, when the attempt is successfully decoded by the at least one relay station, the at least one relay station sends an acknowledgment to a previous relay station in order to clear a buffer in the previous relay station.

15. A communications system comprising:

a plurality of relay stations;

a base station; and

at least one mobile station,

wherein an attempt is forwarded from the base station, through the relay stations, to the at least one mobile station, and

wherein the base station is configured to identify a first relay station which did not successfully receive and decode the attempt and to instruct a previous relay station to generate the attempt that was not successfully decoded.

16. The communications system of claim 15, wherein the attempt comprises a hybrid automatic repeat request attempt.

17. The communications system of claim 15, wherein the attempt comprises a packet.

18. The communications system of claim 15, wherein feedback information is sent from the at least one relay station to the base station.

19. The communications system of claim 18, wherein the base station is configured to identify the first relay station which did not successfully receive and decode the attempt based on the feedback information received from the at least one relay station.

20. A base station comprising:

a transmitter configured to transmit an attempt to at least one relay station;

a receiver configured to receive an acknowledgement from a mobile station when the attempt is successfully decoded by the at least one relay station, and forwarded from the at least one relay station to the mobile station;

an identifying unit configured to identify, when the attempt was not successfully decoded, a first relay station that did not successfully receive and decode the attempt; and

an instructing unit configured to instruct a previous relay station to generate the attempt which was not successfully decoded and to forward the attempt to the first relay station that did not successfully receive and decode the attempt.

21. The base station of claim 20, wherein the transmitter is configured to transmit a hybrid automatic repeat request attempt.

22. The base station of claim 20, wherein the transmitter is configured to transmit a packet.

23. The base station of claim 20, wherein feedback information is sent from the at least one relay station to the base station.

24. The base station of claim 23, wherein the base station is configured to identify the first relay station which did not successfully receive and decode the attempt based on the feedback information received from the at least one relay station.

25. A communications system comprising:

sending means for sending an attempt to at least one relay station, wherein the at least one relay station is configured to decode the attempt and to forward the attempt;

receiving means for receiving an acknowledgement when the attempt is successfully decoded;

identifying means for identifying a first relay station which did not successfully receive and decode the attempt; and

instructing means for instructing a previous relay station to generate the attempt which was not successfully decoded by the first relay station and forwarding the attempt to the first relay station.

26. A mobile station comprising:

a transmitter configured to transmit an attempt to at least one relay station; and

a receiver configured to receive an acknowledgement from a base station when the attempt is successfully decoded by the at least one relay station, and forwarded from the at least one relay station to the base station;

wherein, when the attempt was not successfully decoded, a first relay station that did not successfully receive and decode the attempt is identified, and

wherein a previous relay station is instructed to generate the attempt which was not successfully decoded and to forward the attempt to the first relay station that did not successfully receive and decode the attempt.

27. The mobile station of claim 26, wherein the transmitter is configured to transmit a hybrid automatic repeat request attempt.

28. The mobile station of claim 26, wherein the transmitter is configured to transmit a packet.

29. The mobile station of claim 26, wherein feedback information is sent from the at least one relay station to the mobile station.

30. The mobile station of claim 29, wherein the first relay station which did not successfully receive and decode the attempt is identified based on the feedback information received from the at least one relay station.