Scheduling in a wireless multi-hop relay network

• US 8,135,337 B2
• Filed: 11/29/2005
• Issued: 03/13/2012
• Est. Priority Date: 11/29/2005
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Larsson, Peter
• Primary Examiner(s): Rego, Dominic E
• Application Number:
  US12/095,478
• Publication Number:
  US 20080274692A1
• Time in Patent Office: 2,296 Days
• Field of Search: 455/3.02, 455/427, 455/7, 455/11.1, 455/12.1, 455/13.1, 455/13.2, 455/16, 370/226, 370/293, 370/246, 370/274, 370/279, 370/315, 370/316, 370/492, 370/501
• US Class Current: 455/11.1
• 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 by selecting at least one of said receiving nodes based on received channel quality information and selecting data associated with the selected receiving node(s) for transmission;

said designated originating node transmitting a signal comprising said selected data and a cyclic prefix to the selected receiving node(s) via the same at least one relaying node that forwarded the pilot signal, wherein said network is based on OFDM (Orthogonal Frequency Division Multiplexing) or OFDMA (Orthogonal Frequency Division Multiple Access), and wherein said cyclic prefix is adapted to a power delay profile of an equivalent channel between the designated originating node and the selected receiving node(s) via the at least one relaying node,

said at least one relaying node receiving the signal transmitted by said originating node, and with a latency substantially smaller than the OFDM symbol duration, transmitting the signal in the same frequency band, wherein the signal transmitted by the relaying node constructively interferes with the signal transmitted by the designated originating node when received by the selected receiving node(s).

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 information.

8. 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.

9. The method of claim 8, wherein said originating node and at least one of said receiving nodes have multiple antennas for Multiple-Input Multiple-Output (MIMO)/Multiple-Input Single-Output (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.

10. The method of claim 9, wherein said MIMO operation is a spatial multiplexing based MIMO operation.

11. The method of claim 8, 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 Multiple-Input Multiple-Output (MIMO) or Multiple-Input Single-Output (MISO) communication.

12. 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 by selecting at least one of said receiving nodes based on received channel quality information and selecting data associated with the selected receiving node(s) for transmission;

means, in said designated originating node, for transmitting a signal comprising said selected data and a cyclic prefix to the selected receiving node(s) via the same at least one relaying node that forwarded the pilot signal, wherein said network is based on OFDM (Orthogonal Frequency Division Multiplexing) or OFDMA (Orthogonal Frequency Division Multiple Access), and wherein said cyclic prefix is adapted to a power delay profile of an equivalent channel between the designated originating node and the selected receiving node(s) via the at least one relaying node,

means, in said at least one relaying node, for receiving the signal transmitted by said originating node, and with a latency substantially smaller than the OFDM symbol duration, transmitting the signal in the same frequency band, such that the signal transmitted by the relaying node constructively interferes with the signal transmitted by the designated originating node when received by the selected receiving node(s).

13. The system of claim 12, wherein said wireless relaying network is a cooperative relaying network.

14. The system of claim 13, wherein said cooperative relaying network is a relay-assisted two-hop network.

15. The system of claim 12, 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.

16. The system of claim 15, 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.

17. The system of claim 16, 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.

18. The system of claim 12, 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.

19. The system of claim 12, wherein said at least one relaying node is an amplify-and-forward node.

20. The system of claim 12, wherein said at least one relaying node is a decode-and-forward node.

21. The system of claim 12, wherein said originating node is a base station and said receiving nodes are mobile terminals.

22. The system of claim 12, 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.

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

a transmitting module configured to transmit 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 configured to receive channel quality information from said receiving nodes;

a multi-user diversity scheduler configured to schedule for data for transmission by selecting at least one of said receiving nodes based on said channel quality information obtained from said receiving nodes and to select data associated with the selected receiving node(s) for transmission;

a transmitting module configured to transmit a signal comprising said selected data and a cyclic prefix to the selected receiving node(s) via said at least one relaying node, wherein said transmitting module is configured to transmit in an OFDM—

(Orthogonal Frequency Division Multiplexing) or OFDMA—

(Orthogonal Frequency Division Multiple Access) based network, and wherein said cyclic prefix is adapted to a power delay profile of an equivalent channel between the apparatus and the selected receiving node(s) via said at least one relaying node.

24. The apparatus of claim 23, wherein said apparatus is implemented in a network node.