Scheduling in a Wireless Multi-Hop Relay Network

• US 20080274692A1
• Filed: 11/29/2005
• Published: 11/06/2008
• Est. Priority Date: 11/29/2005
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Larsson, Peter
• Granted Patent: US 8,135,337 B2
• Time in Patent Office: Days
• US Class Current: 455/24
• CPC Class Codes: H04B 7/15592 Adapting at the relay station communication parameters for supporting cooperative relaying, i.e. transmission of the same data via direct - and relayed path cooperative diversity H04B7/024
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 2001/0097 Relays
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0057 Physical resource allocation for CQI
• CPC Class Codes: H04W 40/28 for reactive routing
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff

Abstract

A wireless relaying network having a number of network nodes including a designated originating node, at least one relaying node, and at least two receiving nodes. The designated originating node transmits a pilot signal, and the relaying node(s) receives and forwards the pilot signal to the receiving nodes, each of which measures channel quality based on the received pilot signal. At least part of the receiving nodes feed information on the measured channel quality all the way back to the designated originating node, and the originating node then schedules data for transmission to at least one selected node of the receiving nodes based on the received channel quality information. Subsequently, the designated originating node transmits data to the selected receiving node(s) via the same relaying node(s) that forwarded the pilot signal. In this way, multi-user diversity scheduling is introduced to relaying networks that provides significant data rate enhancements.

Claims

1. A method for relaying information in a wireless relaying network having a number of network nodes, said network comprising a designated originating node, at least one relaying node, and at least two receiving nodes, wherein said method comprises the steps of:

said designated originating node transmitting a pilot signal;

said at least one relaying node receiving and forwarding said pilot signal;

each of said receiving nodes receiving said pilot signal and measuring channel quality based on the received pilot signal;

at least part of said receiving nodes feeding back information on the measured channel quality all the way to said designated originating node;

said designated originating node scheduling data for transmission to at least one selected node of said receiving nodes based on received channel quality information;

said designated originating node transmitting said data to the selected receiving node(s) via the same at least one relaying node that forwarded the pilot signal.

2. The method of claim 1, wherein said wireless relaying network is a cooperative relaying network.

3. The method of claim 2, wherein said cooperative relaying network is a relay-assisted two-hop network.

4. The method of claim 1, wherein said at least one relaying node comprises at least two relaying nodes, for pilot transmission, concurrently and on the same frequency transmitting said pilot signal, and for data transmission, concurrently and on the same frequency transmit data.

5. The method of claim 4, further comprising the step of allocating, to each one of a number of selected relaying nodes, transmit power at least partly based on average link quality for the link between said relay nodes and a selected set of said receiving nodes.

6. The method of claim 5, wherein said step of allocating transmit power is also based on average link quality for the link between said originating node and said set of selected relaying nodes.

7. The method of claim 1, wherein said step of scheduling comprises:

selecting receiving node(s) among those nodes that have the highest value of a channel quality based metric, and;

selecting data associated with the selected node(s) for transmission.

8. The method of claim 1, wherein said network is based on OFDM (Orthogonal Frequency Division Multiplexing) or OFDMA (Orthogonal Frequency Division Multiple Access), and said originating transmitting node and said at least one relaying node are adapted for enabling a direct signal from said originating node and a relayed signal from said at least one relaying node to be received concurrently at said receiving nodes to provide constructive interference of said direct and relayed signals.

9. The method of claim 8, wherein said at least one relaying node is operable for receiving a signal from said originating node and with a latency substantially smaller than the OFDM symbol duration transmitting the signal in the same frequency band.

10. The method of claim 8 or 9, wherein said OFDM(A) network is a cyclic-prefix-based OFDM(A) network, and said designated transmitting node is configured with a cyclic prefix adapted to the power delay profile of the equivalent channel of the relayed signal and the direct signal.

11. The method of claim 1, wherein at least some of said originating node, said at least one relaying node and said receiving nodes have multiple antennas for improved communication operation.

12. The method of claim 11, wherein said originating node and at least one of said receiving nodes have multiple antennas for MIMO/MISO operation and said at least one relaying node each has at least one antenna, and one receiving node is selected for MIMO/MISO based communication.

13. The method of claim 12, wherein said MIMO operation is a spatial multiplexing based MIMO operation.

14. The method of claim 11, wherein said originating node have multiple antennas, and said receiving nodes and said at least one relaying node each have at least one antenna, and at least two receiving nodes are selected for concurrent spatial multiplexing based MISO or MIMO communication.

15. A system for relaying information in a wireless relaying network having a number of network nodes, said network comprising a designated originating node, at least one relaying node, and at least two receiving nodes, wherein said system comprises:

means, in said designated originating node, for transmitting a pilot signal;

means, in said at least one relaying node, for receiving and forwarding said pilot signal;

means, in each of said receiving nodes, for receiving said pilot signal and for measuring channel quality based on the received pilot signal;

means, in at least part of said receiving nodes, for feeding back information on the measured channel quality all the way to said designated originating node;

means, in said designated originating node, for scheduling data for transmission to at least one selected node of said receiving nodes based on received channel quality information;

means, in said designated originating node, for transmitting said data to the selected receiving node(s) via the same at least one relaying node that forwarded the pilot signal.

16. The system of claim 15, wherein said wireless relaying network is a cooperative relaying network.

17. The system of claim 16, wherein said cooperative relaying network is a relay-assisted two-hop network.

18. The system of claim 15, wherein said at least one relaying node comprises at least two relaying nodes, for pilot transmission, concurrently and on the same frequency transmitting said pilot signal, and for data transmission, concurrently and on the same frequency transmitting data.

19. The system of claim 18, further comprising means for allocating, to each one of a number of selected relaying nodes, transmit power at least partly based on average link quality for the link between said relay nodes and a selected set of said receiving nodes.

20. The system of claim 19, wherein said means for allocating transmit power is also based on average link quality for the link between said originating node and said set of selected relaying nodes.

21. The system of claim 15, wherein said means for scheduling comprises:

means for selecting receiving node(s) among those nodes that have the highest value of channel quality; and

means for selecting data associated with the selected node(s) for transmission.

22. The system of claim 15, wherein said at least one relaying node is an amplify-and-forward node.

23. The system of claim 15, wherein said at least one relaying node is a decode-and-forward node.

24. The system of claim 15, wherein said originating node is a base station and said receiving nodes are mobile terminals.

25. The system of claim 15, wherein said network is based on OFDM (Orthogonal Frequency Division Multiplexing) or OFDMA (Orthogonal Frequency Division Multiple Access), and said originating transmitting node and said at least one relaying node are adapted for enabling a direct signal from said originating node and a relayed signal from said at least one relaying node to be received concurrently at said receiving nodes to provide constructive interference of said direct and relayed signals.

26. The system of claim 25, wherein said at least one relaying node is operable for receiving a signal from said originating node and with a latency substantially smaller than the OFDM symbol duration transmitting the signal in the same frequency band.

27. The system of claim 25 or 26, wherein said OFDM(A) network is a cyclic-prefix-based OFDM(A) network, and said designated transmitting node is configured with a cyclic prefix adapted to the power delay profile of the equivalent channel of the relayed signal and the direct signal.

28. The system of claim 15, wherein at least some of said originating node, said at least one relaying node and said receiving nodes have multiple antennas for improved communication operation.

29. An apparatus for use in a relaying network, said apparatus comprising:

a transmitting module for transmitting a pilot signal for the purpose of channel quality measurements in at least two receiving nodes, said pilot signal being received and forwarded to said receiving nodes by at least one relaying node;

a receiving module for receiving channel quality information from said receiving nodes;

a multi-user diversity scheduler for scheduling data for transmission to at least one selected node of said receiving nodes based on said channel quality information obtained from said receiving nodes;

a transmitting module for transmitting said data to the selected receiving node(s) via said at least one relaying node.

30. The apparatus of claim 29, wherein said apparatus is implemented in a network node.

31. A method for improved macro-diversity operation in a wireless communication network, said network comprising a controller, and at least two base stations, in connection with said controller, for communication with at least two mobile terminals, wherein said method comprises the steps of:

said base stations transmitting a pilot signal;

each of said mobile terminals receiving said pilot signal and measuring channel quality based on the received pilot signal;

each of said mobile terminals feeding back information on the measured channel quality all the way to said controller;

said controller scheduling data for transmission to at least one selected terminal of said mobile terminals based on received channel quality information;

transmitting said data to the selected mobile terminal(s) via said base stations.

32. The method of claim 31, further comprising the step of allocating, to each of said at least two base stations, transmit power at least partly based on average link quality for the link between said base stations nodes and a selected set of said mobile terminals.

33. A system for improved macro diversity operation in a wireless communication network, said network comprising a controller, and at least two base stations, in connection with said controller, for communication with at least two mobile terminals, wherein said system comprises:

means, in said base stations, for transmitting a pilot signal;

means, in each of said mobile terminals, for receiving said pilot signal and for measuring channel quality based on the received pilot signal;

means, in each of said mobile terminals, for feeding back information on the measured channel quality all the way to said controller;

means, in said controller, for scheduling data for transmission to at least one selected terminal of said mobile terminals based on received channel quality information;

means for transmitting said data to the selected mobile terminal(s) via said base stations.

34. The system of claim 33, further comprising means for allocating, to each of said at least two base stations, transmit power at least partly based on average link quality for the link between said base stations nodes and a selected set of said mobile terminals.

35. A controller apparatus for connection with at least two base stations in a wireless communication network, said base stations transmitting a pilot signal to at least two mobile terminals for the purpose of channel quality measurements, wherein said controller apparatus comprises:

a receiving module for receiving pilot-based channel quality information from said mobile terminals;

a multi-user diversity scheduler for scheduling data for transmission to at least one selected terminal of said mobile terminals via said base stations based on said pilot-based channel quality information obtained from said mobile terminals.

36. The controller apparatus of claim 35, wherein said controller apparatus comprises a Radio Network Controller (RNC).