Efficient training schemes for MIMO based wireless networks

• US 20070230373A1
• Filed: 03/31/2006
• Published: 10/04/2007
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Li, Qinghua, Perahia, Eldad, Holt, Keith, Stephens, Adrian, Lin, Xintian
• Granted Patent: US 7,804,800 B2
• Time in Patent Office: Days
• US Class Current: 370/267
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0447 utilizing uniform distribution
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0636 Feedback format
• CPC Class Codes: H04B 7/0643 Feedback on request

Abstract

Schemes are disclosed for efficiently training MIMO channels in wireless networks. In at least one embodiment, multiple STAs in a network may share a single channel sounding packet to develop corresponding beamforming matrices or CSI.

Claims

1. A method comprising:

transmitting a channel sounding packet from a first location, via multiple antennas, said channel sounding packet including;

(a) identification information identifying multiple wireless communication devices that are each to generate a beamforming matrix or channel state information (CSI) in response to said channel sounding packet, and (b) an order in which said multiple wireless communication devices are to return packets to said first location in response to said channel sounding packet; and

monitoring a receiver for the arrival of said packets from said multiple wireless communication devices.

2. The method of claim 1, wherein:

said identification information is part of a multicast feedback request within said channel sounding packet, said multicast feedback request requesting said multiple wireless communication devices to each return a feedback packet to said first location that includes a corresponding beamforming matrix or CSI.

3. The method of claim 2, wherein:

monitoring a receiver includes monitoring said receiver for the arrival of said feedback packets from said multiple wireless communication devices.

4. The method of claim 3, further comprising:

receiving said feedback packets in said receiver; and

using said beamforming matrices or CSI in said feedback packets to transmit beamformed data to corresponding wireless communication devices via said multiple antennas.

5. The method of claim 4, wherein:

at least one of said received feedback packets includes a recommendation for a modulation and coding scheme (MCS) to be used to transmit data to a corresponding wireless communication device.

6. The method of claim 4, further comprising:

determining a transmit order in which to transmit data to said multiple wireless communication devices before using said beamforming matrices or CSI to transmit beamformed data.

7. The method of claim 6, wherein:

determining a transmit order includes determining said transmit order based at least upon a channel variation speed associated with each of said multiple wireless communication devices.

8. The method of claim 6, wherein:

determining a transmit order includes determining said transmit order based at least upon an amount of data to be transmitted to each of said multiple wireless communication devices.

9. The method of claim 1, wherein:

said identification information is part of a multicast transmit request within said channel sounding packet, said multicast transmit request requesting said multiple wireless communication devices to each return a beamformed data packet to said first location, said beamformed data packet to be generated using a corresponding beamforming matrix or CSI.

10. The method of claim 9, wherein:

monitoring a receiver includes monitoring said receiver for the arrival of said beamformed data packets from said multiple wireless communication devices.

11. The method of claim 10, further comprising:

receiving said beamformed data packets in said receiver; and

transmitting a block acknowledgement (ACK) packet to said multiple wireless communication devices to acknowledge the successful receipt of said beamformed data packets.

12. The method of claim 11, wherein:

said block ACK packet includes a second multicast transmit request for a subsequent group of data transmissions from wireless communication devices.

13. The method of claim 1, wherein:

said channel sounding packet further includes information identifying a modulation and coding scheme (MCS) that should be used to transmit data.

14. An apparatus comprising:

a wireless transceiver to support wireless communication with remote wireless entities; and

a controller to manage communication activity for the apparatus, said controller including logic to;

generate a channel sounding packet for transmission from said wireless transceiver that includes;

(a) identification information identifying multiple wireless communication devices that are each to generate a beamforming matrix or channel state information (CSI) in response to said channel sounding packet, and (b) an order in which said multiple wireless communication devices are to return packets to said apparatus in response to said channel sounding packet; and

monitor a receiver of said wireless transceiver for the arrival of said packets from said multiple wireless communication devices.

15. The apparatus of claim 14, wherein:

said identification information is part of a multicast feedback request within said channel sounding packet, said multicast feedback request requesting said multiple wireless communication devices to each return a feedback packet to said first location that includes a corresponding beamforming matrix or CSI.

16. The apparatus of claim 14, wherein:

said identification information is part of a multicast transmit request within said channel sounding packet, said multicast transmit request requesting said multiple wireless communication devices to each return a beamformed data packet to said first location, said beamformed data packet to be generated using a corresponding beamforming matrix or CSI.

17. A system comprising:

a plurality of antennas, said plurality of antennas including at least one dipole antenna,

a wireless transceiver, coupled to said plurality of antennas, to support wireless communication with remote wireless entities; and

a controller to manage communication activity for the system, said controller including logic to;

generate a channel sounding packet for transmission from said wireless transceiver that includes;

(a) identification information identifying multiple wireless communication devices that are each to generate a beamforming matrix or CSI in response to said channel sounding packet, and (b) an order in which said multiple wireless communication devices are to return packets to said system in response to said channel sounding packet; and

monitor a receiver of said wireless transceiver for the arrival of said packets from said multiple wireless communication devices.

18. The system of claim 17, wherein:

said identification information is part of a multicast feedback request within said channel sounding packet, said multicast feedback request requesting said multiple wireless communication devices to each return a feedback packet to said first location that includes a corresponding beamforming matrix or CSI.

19. The system of claim 17, wherein:

said identification information is part of a multicast transmit request within said channel sounding packet, said multicast transmit request requesting said multiple wireless communication devices to each return a beamformed data packet to said first location, said beamformed data packet to be generated using a corresponding beamforming matrix or CSI.

20. An article comprising a storage medium having instructions stored thereon that, when executed by a computing platform, operate to:

generate a channel sounding packet including;

(a) identification information identifying multiple wireless communication devices that are each to generate a beamforming matrix or CSI in response to said channel sounding packet, and (b) an order in which said multiple wireless communication devices are to return packets in response to said channel sounding packet;

cause said channel sounding packet to be transmitted via multiple antennas; and

monitor a receiver for the arrival of said packets from said multiple wireless communication devices.

21. The article of claim 20, wherein:

said identification information is part of a multicast feedback request within said channel sounding packet, said multicast feedback request requesting said multiple wireless communication devices to each return a feedback packet that includes a corresponding beamforming matrix or CSI.

22. The article of claim 20, wherein:

said identification information is part of a multicast transmit request within said channel sounding packet, said multicast transmit request requesting said multiple wireless communication devices to each return a beamformed data packet, said beamformed data packet to be generated using a corresponding beamforming matrix or CSI.

23. A method comprising:

transmitting a channel sounding packet from a first location, via multiple antennas, said channel sounding packet including a feedback request requesting a first wireless communication device to generate a first beamforming matrix or CSI using said channel sounding packet and to feed back said first beamforming matrix or CSI to said first location;

receiving a feedback packet from said first wireless communication device that includes said first beamforming matrix or CSI;

transmitting a beamformed data packet to said first wireless communication device using said first beamforming matrix from said feedback packet; and

receiving a feedback packet from a second wireless communication device that includes a second beamforming matrix or CSI, said second beamforming matrix or CSI having been generated within said second wireless communication device using said beamformed data packet transmitted to said first wireless communication device.

24. The method of claim 23, wherein:

said beamformed data packet transmitted to said first wireless communication device includes a feedback request requesting said second wireless communication device to generate said second beamforming matrix or CSI using said beamformed data packet and to feed back said second beamforming matrix or CSI to said first location.

25. The method of claim 23, wherein:

said second beamforming matrix or CSI was generated by said second wireless communication device and fed back to said first location without a feedback request, said second wireless communication device having knowledge, before generating said second beamforming matrix or CSI , that data exists at said first location that needs to be transmitted to said second wireless communication device.

26. The method of claim 23, further comprising:

matrix multiplying said first beamforming matrix and said second beamforming matrix to achieve a third beamforming matrix; and

transmitting a second beamformed data packet to said second wireless communication device using said third beamforming matrix.

27. The method of claim 26, wherein:

said second beamformed data packet that is transmitted to said second wireless communication device includes a feedback request requesting a third wireless communication device to generate a fourth beamforming matrix using said second beamformed data packet and to feed back said fourth beamforming matrix to said first location.

28. The method of claim 23, wherein:

said second wireless communication device uses at least one of the following from said beamformed data packet to generate said second beamforming matrix;

a preamble, beacons, pilots, and user data.

29. An apparatus comprising:

a wireless transceiver to support wireless communication with remote wireless entities; and

a controller to manage communication activity for said apparatus, said controller including logic to generate a sounding packet, for transmission from said wireless transceiver, that is to be shared by multiple remote wireless communication devices to generate corresponding beamforming matrices or channel state information (CSI).

30. The apparatus of claim 29, wherein:

said controller includes logic to generate a first packet, before said sounding packet is generated, that includes;

(a) identification information identifying said multiple wireless communication devices that are to share said sounding packet, (b) a time offset of a scheduled downlink transmission that is to include said sounding packet, and (c) time offsets of scheduled uplink transmissions from said multiple wireless communication devices, said uplink transmissions to include beamforming matrices or CSI associated with said multiple wireless communication devices.

31. The apparatus of claim 30, wherein:

said controller includes logic to monitor a receive channel for said scheduled uplink transmissions at said corresponding time offsets.

32. The apparatus of claim 30, wherein:

said first packet further includes;

(d) duration information specifying a duration of said scheduled downlink transmission, and (e) duration information specifying durations of said scheduled uplink transmissions.

33. The apparatus of claim 29, wherein said sounding packet includes:

identification information identifying said multiple remote wireless communication devices; and

an order in which said multiple remote wireless communication devices are to return packets to said first location in response to said sounding packet.