Calibration systems and techniques for distributed beamforming

• US 20080003948A1
• Filed: 06/29/2006
• Published: 01/03/2008
• Est. Priority Date: 06/29/2006
• Status: Abandoned Application

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Mitran, Patrick
• Application Number:
  US11/477,244
• Publication Number:
  US 20080003948A1
• Time in Patent Office: Days
• US Class Current: 455/67.11
• CPC Class Codes: H04B 17/14 of the whole transmission and reception path, e.g. self-test loop-back
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0617 for beam forming

Abstract

Various embodiments of calibration systems and techniques for distributed beamforming are described. In one embodiment, an apparatus may comprise a first transmitter node to cooperate with a second transmitter node for cooperatively communicating with a receiver node. Effective channel knowledge may be acquired for channels between the first and second transmitter nodes and the receiver node. The transmit and receive chains of the first and second transmitter nodes may be calibrated based on the effective channel knowledge. Other embodiments are described and claimed.

Claims

1. An apparatus comprising:

a first transmitter node to cooperate with a second transmitter node for cooperatively communicating with a receiver node by acquiring effective channel knowledge of channels between the first and second transmitter nodes and the receiver node and calibrating transmit and receive chains of the first and second transmitter nodes based on the effective channel knowledge.

2. The apparatus of claim 1, the first transmitter node to send a sounding frame to the second transmitter node.

3. The apparatus of claim 1, the first transmitter node to receive a sounding frame from the second transmitter node.

4. The apparatus of claim 1, at least one of the first transmitter node and the second transmitter node to receive a sounding frame from the receiver node.

5. The apparatus of claim 1, the first and second transmitter nodes to pre-multiply transmissions to the receiver node by a scalar based on the acquired effective channel knowledge.

6. The apparatus of claim 1, the receiver node to realize one or more of beamforming gain and an improved signal-to-noise ratio.

7. The apparatus of claim 1, wherein:

the effective channel knowledge for the channel H_AB between the first transmitter node and the second transmitter node comprises β

_BH_ABα

_A, where α

_A models the transmit chain of the first transmitter node and β

_B models the receive chain of the second transmitter node; and

the effective channel knowledge for the channel H_BA between the second transmitter node and the first transmitter node comprises β

_AH_BAα

_B, where α

_B models the transmit chain of the second transmitter node and β

_A models the receive chain of the first transmitter node.

8. The apparatus of claim 7, wherein:

the effective channel knowledge for the channel H_DA between the receiver node and the first transmitter node comprises β

_AH_DAα

_D, and the effective channel knowledge for the channel H_DB between the receiver node and the second transmitter node comprises β

_BH_DBα

_D, where α

_D models the transmit chain of the receiver node.

9. The apparatus of claim 8, the first transmitter node to pre-multiply a transmission by a complex scalar β

_AH_BAα

_B(β

_AH_DAα

_D)*, and the second transmitter node to pre-multiply the transmission by a complex scalar β

_BH_ABα

_A(β

_BH_DBα

_D)*, where the (*) denotes complex conjugation.

10. The apparatus of claim 8, the first transmitter node to pre-multiply a transmission by a complex scalar β

_AH_BAα

_B(β

_AH_DAα

_D)*/N₁, and the second transmitter node to pre-multiply the transmission by a complex scalar β

_BH_ABα

_A(β

_BH_DBα

_D)*/N₂, where the (*) denotes complex conjugation, N₁ comprises a real valued normalization factor, and N₂ comprises a real-valued normalization constant.

11. The apparatus of claim 8, wherein a transmitted symbol (s) received at the receiver node comprises:

12. The apparatus of claim 1, the receiver node to acquire effective channel knowledge of channels from the first and second transmitter nodes.

13. A system comprising:

a first transmitter node to cooperate with a second transmitter node for cooperatively communicating with a receiver node by acquiring effective channel knowledge of channels between the first and second transmitter nodes and the receiver node and calibrating transmit and receive chains of the first and second transmitter nodes based on the effective channel knowledge; and

a source node coupled to the first transmitter node through a communication medium to deliver a packet for delivery to the receiver node.

14. The system of claim 13, the first transmitter node and the second transmitter node to exchange sounding frames.

15. The system of claim 13, the first transmitter node and the second transmitter node to receive a sounding frame from the receiver node.

16. The system of claim 13, the first and second transmitter nodes to pre-multiply transmissions to the receiver node by a scalar based on the acquired effective channel knowledge.

17. The system of claim 13, the receiver node to realize one or more of beamforming gain and an improved signal-to-noise ratio.

18. The system of claim 13, wherein the receiver node is not in range of the source node.

19. The system of claim 18, wherein the range of the source node is increased by phase adjustments based on channel knowledge.

20. A method comprising:

sounding effective channels between transmitter nodes;

sounding effective channels between the transmitter nodes and a receiver node; and

collaboratively communicating between the transmitter nodes and the receiver node.

21. The method of claim 20, further comprising acquiring effective channel knowledge of channels between the transmitter nodes and the receiver node.

22. The method of claim 21, further comprising calibrating transmit and receive chains of the transmitter nodes based on the acquired effective channel knowledge.

23. The method of claim 21, further comprising pre-multiplying transmissions from the transmitter nodes to the receiver node by a scalar based on the acquired effective channel knowledge.

24. The method of claim 20, further comprising:

acquiring channel knowledge for a channel H_AB between a first transmitter node and a second transmitter node comprising β

_BH_ABα

_A, where α

_A models a transmit chain of the first transmitter node and β

_B models a receive chain of the second transmitter node; and

acquiring effective channel knowledge for a channel H_BA between the second transmitter node and the first transmitter node comprising β

_AH_BAα

_B, where α

_B models a transmit chain of the second transmitter node and β

_A models a receive chain of the first transmitter node.

25. The method of claim 24, further comprising:

acquiring effective channel knowledge for a channel H_DA between the receiver node and the first transmitter node comprising β

_AH_DAα

_D, and effective channel knowledge for a channel H_DB between the receiver node and the second transmitter node comprising β

_BH_DBα

_D, where α

_D models a transmit chain of the receiver node.

26. The method of claim 25, further comprising:

transmitting a symbol (s) from the first transmitter node comprising;

β

_AH_BAα

_B(β

_AH_DAα

_D)*s/|β

_AH_BAα

_Bβ

_AH_DAα

_D|; and

transmitting the symbol (s) from the second transmitter node comprising;

β

_BH_ABα

_A(β

_BH_DBα

_D)*s/|β

_BH_ABα

_Aβ

_BH_DBα

_D|.

27. The method of claim 26, further comprising receiving the symbol (s) at the receiver node comprising:

28. An article comprising a machine-readable storage medium containing instructions that if executed enable a system to:

sound effective channels between transmitter nodes;

sound effective channels between the transmitter nodes and a receiver node; and

collaboratively communicate between the transmitter nodes and the receiver node.

29. The article of claim 28, further comprising instructions that if executed enable a system to acquire effective channel knowledge of channels between the transmitter nodes and the receiver node.

30. The article of claim 29, further comprising instructions that if executed enable a system to calibrate transmit and receive chains of the transmitter nodes based on the acquired effective channel knowledge.

31. The article of claim 29, further comprising instructions that if executed enable a system to pre-multiply transmissions from the transmitter nodes to the receiver node by a scalar based on the acquired effective channel knowledge.

32. The article of claim 28, further comprising instructions that if executed enable a system to send and receive sounding frames.