Antenna Systems and Methods for massive MIMO Communication

• US 20140307814A1
• Filed: 09/30/2013
• Published: 10/16/2014
• Est. Priority Date: 04/15/2013
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: JALLOUL, Louay, MOBASHER, Amin, ALEX, Sam
• Granted Patent: US 9,407,337 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0404 the mobile station comprising multiple antennas, e.g. to provide uplink diversity
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0684 using different training sequences per antenna
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04L 25/0202 Channel estimation
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals

Abstract

Antenna systems and methods for Massive Multi-Input-Multi-Output (MIMO) (M-MIMO) communication are provided. Antennas systems include a M-MIMO transmitter architecture with a hybrid matrix structure. The hybrid matrix structure protects against transmit path component failures and ensures that a spatial rate of the MIMO transmitter is not degraded by the failures. Antenna systems and methods also include antenna selection schemes for selecting a subset of antennas from a plurality of antennas to transmit to a receiver.

Claims

1. A Multi-Input-Multi-Output (MIMO) antenna system, comprising:

a plurality of first antennas; and

a measurement module, coupled to the plurality of first antennas, configured to estimate a channel from the plurality of first antennas to a plurality of second antennas and to select a subset of the plurality of first antennas, based on the estimated channel, for transmitting a plurality of signals to the plurality of second antennas.

2. The MIMO antenna system of claim 1, wherein the plurality of first antennas are located at a base station, and the plurality of second antennas are located at a user equipment (UE).

3. The MIMO antenna system of claim 1, further comprising:

an antenna selection matrix configured to receive the plurality of signals for transmission,

wherein the measurement module is further configured to control the antenna selection matrix to couple the plurality of signals to the selected subset of the plurality of first antennas.

4. The MIMO antenna system of claim 3, wherein the antenna selection matrix includes an M-input N-output switch matrix, where M is equal to the number of the plurality of signals and N is equal to the number of the plurality of first antennas.

5. The MIMO antenna system of claim 4, further comprising:

a first M-input M-output hybrid matrix configured to receive a plurality of input signals and to generate a respective plurality of hybrid signals, wherein each of the plurality of hybrid signals is a combination of the plurality of input signals;

a plurality of power amplifiers (PAs) each configured to receive a respective one of the plurality of hybrid signals and to generate a respective one of a plurality of amplified hybrid signals; and

a second M-input M-output hybrid matrix configured to receive the plurality of amplified hybrid signals and to generate the plurality of signals, wherein each of the plurality of signals is a combination of the plurality of amplified hybrid signals.

6. The MIMO antenna system of claim 1, wherein the measurement module is further configured to receive, from at least one of the plurality of first antennas, a plurality of reference signals transmitted respectively by the plurality of second antennas and to estimate the channel using the plurality of reference signals.

7. The MIMO antenna system of claim 6 wherein the plurality of reference signals include sounding reference signals (SRS).

8. The MIMO antenna system of claim 1, wherein the size of the selected subset of the plurality of first antennas is equal to M, and wherein the measurement module is further configured, for each subset of size M of the plurality of first antennas:

form, using the estimated channel, a sub-channel matrix h corresponding to a sub-channel between the subset and the plurality of second antennas;

form a channel matrix A equal to a product of the conjugate transpose of h by h;

perform a singular value decomposition (SVD) of A to determine a unitary matrix U, a diagonal matrix D having positive diagonal elements, and an orthogonal matrix V; and

compute a function of the positive diagonal elements of the diagonal matrix D.

9. The MEMO antenna system of claim 8, wherein the function is a sum of the positive diagonal elements of the diagonal matrix D.

10. The MIMO antenna system of claim 8, wherein the measurement module is further configured to choose the subset with the largest function as the selected subset of the plurality of first antennas.

11. The MIMO antenna system of claim 1, wherein the size of the selected subset of the plurality of first antennas is equal to M, and wherein the measurement module is further configured to:

determine a matrix H wherein each column vector h of H corresponds to a respective sub-channel between the plurality of first antennas and a respective one of the plurality of second antennas;

form, for each column vector h of H, a respective vector y by squaring each element of the column vector h;

form a vector S by adding the vectors y;

determine the M largest elements of the vector S; and

select M antennas of the plurality of first antennas that correspond to the M largest elements of vector S as the selected subset of the plurality of first antennas.

12. A method for Massive Multi-Input-Multi-Output (MIMO) (M-MIMO) antenna selection, comprising:

estimating a channel from a plurality of first antennas to a plurality of second antennas;

selecting, based on the estimated channel, a subset of the plurality of first antennas; and

transmitting a plurality of signals to the plurality of second antennas using the subset of the plurality of first antennas.

13. The method of claim 12, *herein the plurality of first antennas are located at a base station, and the plurality of second antennas arc located at a user equipment (UE).

14. The method of claim 12, further comprising:

receiving, from at least one of the plurality of first antennas, a plurality of reference signals transmitted respectively by the plurality of second antennas; and

estimating the channel using the plurality of reference signals.

15. The method of claim 12, wherein the size of the selected subset of the plurality of first antennas is equal to M, and wherein the method further comprises, for each subset of size M of the plurality of first antennas:

forming, using the estimated channel, a subset channel matrix h corresponding to a sub-channel between the subset and the plurality of second antennas;

forming a channel matrix A equal to a product of the conjugate transpose of h by h;

performing a singular value decomposition (SVD) of A to determine a unitary matrix U, a diagonal matrix D having positive diagonal elements, and an orthogonal matrix V; and

computing a function of the positive diagonal elements of the diagonal matrix D.

16. The method of claim 15, wherein the function is a sum of the positive diagonal elements of the diagonal matrix D.

17. The method of claim 15, further comprising:

choosing the subset with the largest function as the selected subset of the plurality of first antennas.

18. The method of claim 12, wherein the size of the selected subset of the plurality of first antennas is equal to M, and wherein the method further comprises:

determining a matrix H wherein each column vector h of H corresponds to a respective sub-channel between the plurality of first antennas and a respective one of the plurality of second antennas;

forming, for each column vector h of H, a respective vector y by squaring each element of the column vector h;

forming a vector S by adding the vectors y;

determining the M largest elements of the vector S; and

selecting M antennas of the plurality of first antennas that correspond to the M largest elements of vector S as the selected subset of the plurality of first antennas.

19. A Multi-Input-Multi-Output (MIMO) antenna system, comprising:

a first hybrid matrix configured to receive a plurality of input signals and to generate a respective plurality of hybrid signals, wherein each of the plurality of hybrid signals is a combination of the plurality of input signals;

a plurality of power amplifiers (PAs) each configured to receive a respective one of the plurality of hybrid signals and to generate a respective one of a plurality of amplified hybrid signals;

a second hybrid matrix configured to receive the plurality of amplified hybrid signals and to generate a respective plurality of output signals, wherein each of the plurality of output signals is a combination of the plurality of amplified hybrid signals; and

a plurality of antennas each configured to transmit a respective one of the plurality of output signals.

20. The MIMO antenna system of claim 19, wherein the first hybrid matrix and the second hybrid matrix have inverse transfer functions.