METHOD AND APPARATUS FOR RELAYING SPATIALLY-MULTIPLEXED SIGNALS

• US 20080002601A1
• Filed: 06/30/2006
• Published: 01/03/2008
• Est. Priority Date: 06/30/2006
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Schott, Wolfgang H., Coronel, Pedro E.
• Application Number:
  US11/427,833
• Publication Number:
  US 20080002601A1
• Time in Patent Office: Days
• US Class Current: 370/315
• CPC Class Codes: H04B 7/026 Co-operative diversity, e.g. using fixed or mobile stations as relays
• CPC Class Codes: H04B 7/0434 using multiple eigenmodes
• CPC Class Codes: H04B 7/0465 taking power constraints at power amplifier or emission constraints, e.g. constant modulus, into account
• CPC Class Codes: H04B 7/155 Ground-based stations H04B7/204 takes precedence
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user

Abstract

The present invention discloses a MIMO relay apparatus comprising a data source node, a relay node, and a destination node. The data source node sends a source send data x over a first radio channel H. The relay node receives a relay receive data y_r from said first radio channel H, applying a relay transformation Φ to relay receive data y_r to obtain a relay send data x_r. The relay node further sends relay send data x_r over a second radio channel G. The destination node receives a destination receive data y from second radio channel G, and applies a destination transformation Ψ to destination receive data y to obtain a destination output data r representing an estimate of said source send data x. Relay transformation Φ and said destination transformation Ψ are jointly tuned with respect to each other.

Claims

1. A MIMO relay apparatus comprising:

a data source node sending a source send data x over a first radio channel H;

a relay node receiving a relay receive data y_r from said first radio channel H, applying a relay transformation Φ

to said relay receive data y_r to obtain a relay send data x_r, and sending relay send data x_r over a second radio channel G; and

a destination node receiving a destination receive data y from said second radio channel G, and applying a destination transformation Ψ

to said destination receive data y to obtain a destination output data r representing an estimate of said source send data x;

wherein said relay transformation Φ and

said destination transformation Ψ

are jointly tuned with respect to each other.

2. The MIMO relay apparatus of claim 1, wherein the joint tuning of said relay transformation Φ

and said destination transformation Ψ

reduces a mean square error (MSE) between said source send data x and said destination output data r.

3. The MIMO relay apparatus of claim 1, wherein said relay transformation Φ

and said destination transformation Ψ

are jointly tuned by applying the Lagrange method and Karush-Kuhn-Tucker conditions to the problem of reducing the mean square error (MSE) between said source send data x and said destination output data r.

4. The MIMO relay apparatus of claim 1, wherein said relay transformation Φ

and said destination transformation Ψ

are chosen so that said destination output data r is the maximum-likelihood estimate of said source send data x.

5. The MIMO relay apparatus of claim 1, wherein at least one of said data source node, said relay node, and said destination node is a wireless communication device compliant with a communication standard selected from a group consisting of Institute of Electrical and Electronics Engineers (IEEE) 802.11n Wireless Local Area Network (WLAN), IEEE 802.16 Wireless Metropolitan Area Network (WMAN), IEEE 802.16a WMAN, IEEE 802.20 Mobile Broadband Wireless Access (MBWA), Third Generation Partnership Project 2 (3GPP2), and 4th Generation (4G).

6. A MIMO wireless network node for operating within a network having a source send data x supplied by a data source node in the network and a destination output data r generated by a destination node, said MIMO wireless network node comprising:

a data processor configured to apply at least one of a relay transformation Φ

or a destination transformation Ψ

to data supplied to said data processor;

when relay transformation Φ

is applied, relay transformation Φ

is jointly tuned with respect to destination transformation Ψ and

, when destination transformation Ψ

is applied, destination transformation Ψ

is jointly tuned with respect to relay transformation Φ

.

7. The MIMO wireless node of claim 6, wherein the joint tuning of said relay transformation Φ

and said destination transformation Ψ

reduces the mean square error (MSE) between said source send data x and said destination output data r.

8. The MIMO wireless network node of claim 6, wherein said relay transformation Φ

and said destination transformation Ψ

are jointly tuned by applying the Lagrange method and Karush-Kuhn-Tucker conditions to the problem of reducing the mean square error (MSE) between said source send data x and said destination output data r.

9. The MIMO wireless network node of claim 6, wherein said data processor applies said relay transformation Φ

on a relay receive data y_r to get a relay send data x_r.

10. The MIMO wireless network node of claim 6, wherein said data processor applies said destination transformation Ψ

on a destination receive data y to get destination output data r.

11. The MIMO wireless network node claim 6, wherein said relay transformation Φ

and said destination transformation Ψ

are chosen so that said destination output data r is the maximum-likelihood estimate of said source send data x.

12. The MIMO wireless network node of claim 6, wherein said data processor is coupled with a wireless communication device compliant with a communication standard selected from a group consisting of Institute of Electrical and Electronics Engineers (IEEE) 802.11n Wireless Local Area Network (WLAN), IEEE 802.16 Wireless Metropolitan Area Network (WMAN), IEEE 802.16a WMAN, IEEE 802.20 Mobile Broadband Wireless Access (MBWA), Third Generation Partnership Project 2 (3GPP2), and 4th Generation (4G).

13. An apparatus for relaying a source send data x from a data source node to a destination node, said apparatus comprising:

a Multiple-Input Multiple-Output (MIMO) antenna array to receive a relay receive data y_r and to send a relay send data x_r; and

a relay data processor for performing a relay transformation Φ

on said relay receive data y_r to form said relay send data x_r, wherein said relay transformation Φ

is jointly tuned with a destination transformation Ψ

, wherein said destination node applies said destination transformation Ψ

to compute a destination output data r.

14. The apparatus of claim 13, wherein said relay transformation Φ

is jointly tuned with said destination transformation Ψ

to reduce the mean square error (MSE) between said source send data x and said destination output data r.

15. The apparatus of claim 13, wherein said relay transformation Φ

and said destination transformation Ψ

are jointly tuned by applying the Lagrange method and Karush-Kuhn-Tucker conditions to the problem of reducing the mean square error (MSE) between said source send data x and said destination output data r.

16. The apparatus of claim 13, wherein said relay data processor comprises:

a singular value decomposition logic configured to perform singular value decomposition of matrices representing said first radio channel H and said second radio channel G, to obtain first singular values σ

_K and second singular values λ

_K;

a pair-wise product calculation logic configured to compute pair-wise products δ

_K of said first singular values σ

_K and said second singular values λ

_K;

a sorting logic configured to sort said pair-wise products δ

_K in descending order;

a Lagrange logic configured to calculate an Lagrange multiplier μ

using said pair-wise products δ

_K and said second singular values λ

_K;

a diagonal elements calculation logic configured to calculate a relay vector d_Φ

and a destination vector d_Ψ

using said Lagrange multiplier μ

;

an MSE calculation logic configured to calculate the expected MSE between said source send data x and said destination output data r if said relay transformation Φ and

said destination transformation Ψ

are formed using said relay vector d_Φ

and said destination vector d_Ψ

;

a control logic configured to identify a chosen permutation π

^# of said second singular values λ

_K that yields the least MSE between said destination output data r and said source send data x; and

transformation forming logic configured to form at least one of said relay transformation Φ and

said destination transformation Ψ

using said relay vector d_Φ

and said destination vector d_Ψ

corresponding to said chosen permutation π

^#.

17. The apparatus of claim 13, wherein said relay transformation Φ

and said destination transformation Φ

are chosen so that said destination output data r is the maximum-likelihood estimate of said source send data x.

18. An apparatus for receiving a source send data x from a data source node through a relay node, said apparatus comprising:

a Multiple-Input Multiple-Output (MIMO) antenna array to receive a destination receive data y; and

a destination data processor for performing a destination transformation Ψ

on said destination receive data y to form a destination output data r, wherein said destination transformation Ψ

is jointly tuned with a relay transformation Φ

, wherein said relay node applies said relay transformation Φ

for relaying data.

19. The apparatus of claim 18, wherein said destination transformation Ψ

is jointly tuned with said relay transformation Φ

to reduce the mean square error (MSE) between said source send data x and said destination output data r.

20. The apparatus of claim 18, wherein said relay transformation Φ

and said destination transformation Ψ

are jointly tuned by applying Lagrange tuning and Karush-Kuhn-Tucker conditions to the problem of reducing the mean square error (MSE) between said source send data x and said destination output data r.

21. The apparatus of claim 18, wherein said destination data processor comprises:

a singular value decomposition logic configured to perform singular value decomposition of matrices representing said first radio channel H and said second radio channel G, to obtain first singular values σ

_K and second singular values λ

_K;

a pair-wise product calculation logic configured to compute pair-wise products δ

_K of said first singular values σ

_K and said second singular values λ

_K;

a sorting logic configured to sort said pair-wise products δ

_K in descending order;

a Lagrange logic configured to calculate an Lagrange multiplier μ

using said pair-wise products δ

_K and said second singular values λ

_K;

a diagonal elements calculation logic configured to calculate a relay vector d_Φ

and a destination vector d_Ψ

using said Lagrange multiplier μ

,

an MSE calculation logic configured to calculate the expected MSE between said source send data x and said destination output data r if said relay transformation Φ and

said destination transformation Ψ

are formed using said relay vector d_Φ

and said destination vector d_Ψ

;

a control logic configured to identify a chosen permutation π

^# of said second singular values λ

_K that yields the least MSE between said destination output data r and said source send data x; and

transformation forming logic configured to form at least one of said relay transformation Φ and

said destination transformation Ψ

using said relay vector d_Φ

and said destination vector d_Ψ

corresponding to said chosen permutation π

^#.

22. The apparatus of claim 18, wherein said relay transformation Φ

and said destination transformation Ψ

are chosen so that said destination output data r is the maximum-likelihood estimate of said source send data x.

23. A method of operating MIMO wireless network node within a network having a source send data x supplied by a data source node in the network and a destination output data r generated by a destination node, said method comprising:

applying at least one of a relay transformation Φ

or a destination transformation Ψ

to data supplied to said MIMO wireless network node;

when relay transformation Φ

is applied, relay transformation Φ

is jointly tuned with respect to destination transformation Ψ and

, when destination transformation Ψ

is applied, destination transformation Ψ

is jointly tuned with respect to relay transformation Φ

.

24. The method of claim 23, wherein said relay transformation Φ

and said destination transformation Ψ

are jointly tuned by applying the Lagrange method and Karush-Kuhn-Tucker conditions to the problem of reducing the mean square error (MSE) between said source send data x and said destination output data r.

25. The method of claim 23 further comprising:

performing singular value decomposition of said first radio channel H to obtain a set of first singular values σ

_K;

performing singular value decomposition of said second radio channel G to obtain a set of second singular values λ

_K;

for at least one permutation π

of pairing of said first singular values σ

_K and said second singular values λ

_K, performing the following steps;

computing pair-wise products δ

_K of said first singular values σ

_K and said second singular values λ

_K for said permutation π

;

sorting said pair-wise products δ

_K in descending order;

calculating an Lagrange multiplier μ

for said permutation π

;

calculating a relay vector d_Φ

and a destination vector d_Ψ

using said Lagrange multiplier μ

; and

calculating the mean square error (MSE) between said destination output data r and said source send data x using said Lagrange multiplier μ

, said relay vector d_Φ

, and said destination vector d_Ψ

;

selecting a chosen permutation π

^# that yields the least MSE between said destination output data r and said source send data x; and

forming at least one of said relay transformation Φ and

said destination transformation Ψ

using said relay vector d_Φ

and said destination vector d_Ψ

corresponding to said chosen permutation π

^#.

26. The method of claim 25, wherein calculating said Lagrange multiplier μ

comprises;

initializing a mode count to the number of sub-signals Ms in said source send data x;

computing a value of Lagrange multiplier μ

;

testing said value of Lagrange multiplier μ

for an admissibility condition;

decrementing said mode count and returning to said step of computing, if said value of Lagrange multiplier μ

fails the admissibility condition test; and

identifying said value of Lagrange multiplier μ

as said Lagrange multiplier μ

, if said value of Lagrange multiplier μ

passes the admissibility condition test.

27. The method of claim 23, wherein said relay transformation Φ

and said destination transformation Ψ

are chosen so that said destination output data r is the maximum-likelihood estimate of said source send data x.