DYNAMIC SPACE DIVISION DUPLEX (SDD) WIRELESS COMMUNICATIONS WITH MULTIPLE ANTENNAS USING SELF-INTERFERENCE CANCELLATION

• US 20130114468A1
• Filed: 11/07/2011
• Published: 05/09/2013
• Est. Priority Date: 11/07/2011
• Status: Active Grant

• Current Assignee: SAGO Strategic Solutions LLC
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Hui, Dennis, Guey, Jiann-Ching
• Granted Patent: US 9,019,849 B2
• Time in Patent Office: Days
• US Class Current: 370/277
• CPC Class Codes: H01Q 3/2611 Means for null steering; Adaptive interference nulling
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0478 Special codebook structures directed to feedback optimisation
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04B 7/0874 using subgroups of receive antennas
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex

Abstract

A system and method to perform Full Duplex (FD) Space Division Duplex (SDD) communication using a Self-Interference Cancelling (SIC) precoder that applies different antenna phase shifts and amplitude scales to the transmitted signals to force them to be in the null space of the selected receive antennas. Thus, a wireless communication unit can place nulls at each of its receive antennas digitally at baseband for one or more frequency bands. The SIC precoder may be computed based on the self-interference channel from the transmit chain(s) to the receive chain(s). Different SIC precoders may be adaptively selected and stored digitally for different frequency bands. Subsequent single or multi-user precoder can be applied in concatenation with the SIC precoder to transmit signals to one or more users while receiving signals from one or more users simultaneously over the same frequency band.

Claims

1. A method of providing full-duplex communication in a pre-determined frequency band using a wireless communication unit having a plurality of antennas, the method comprising the steps of:

the wireless unit receiving one or more receive data streams in the pre-determined frequency band utilizing a first subset of the plurality of antennas, wherein the first subset includes at least one antenna from the plurality of antennas as a receive antenna;

the wireless unit simultaneously transmitting one or more transmit data streams in the pre-determined frequency band utilizing a second subset of the plurality of antennas, wherein the second subset includes less than or equal to the total number of antennas in the plurality of antennas as transmit antennas; and

the wireless unit adjusting the relative amplitudes and relative phases of radio signals carrying the transmit data streams that are transmitted through the transmit antennas in the pre-determined frequency band, thereby configuring all transmit antennas to collectively place a substantial null at each receive antenna when transmitting in the predetermined frequency band.

2. The method of claim 1, wherein the first subset of the plurality of antennas includes a fixed number of antennas from the plurality of antennas to operate as receive antennas.

3. The method of claim 1, wherein the pre-determined frequency band includes any frequency band from a plurality of pre-determined frequency bands.

4. The method of claim 3, wherein the step of wireless unit adjusting the relative amplitudes and relative phases of transmitted radio signals includes:

the wireless unit determining a plurality of Self-Interference Cancelling (SIC) precoders, each SIC precoder corresponding to one of the plurality of pre-determined frequency bands; and

the wireless unit selecting a SIC precoder from the plurality of SIC precoders depending on which of the pre-determined frequency bands the radio signals are transmitted in.

5. The method of claim 1, wherein the step of wireless unit receiving data streams utilizing the first subset of the plurality of antennas includes:

the wireless unit dynamically selecting one or more of the plurality of antennas to be included in the first subset in a frequency-dependent manner.

6. The method of claim 5, wherein the step of wireless unit dynamically selecting one or more of the plurality of antennas includes:

the wireless unit selecting one or more of the plurality of antennas to be included in the first subset associated with the pre-determined frequency band in such a manner as to maximize a weighted sum of a transmission throughput and a reception throughput, wherein the transmission throughput is associated with Multiple-Input Multiple-Output (MIMO) transmissions from the wireless unit to a first plurality of users, and wherein the reception throughput is associated with MIMO receptions by the wireless unit from a second plurality of users.

7. The method of claim 1, wherein the step of wireless unit receiving data streams utilizing the first subset of the plurality of antennas includes:

the wireless unit dynamically selecting one or more of the plurality of antennas to be included in the first subset in a time-dependent manner.

8. The method of claim 1, wherein the step of wireless unit transmitting one or more transmit data streams includes:

the wireless unit transmitting the one or more transmit data streams to a first plurality of users,

and wherein in the step of wireless unit receiving one or more receive data streams includes;

the wireless unit receiving the one or more receive data streams from a second plurality of users.

9. The method of claim 1, wherein the step of wireless unit adjusting the relative amplitudes and relative phases of transmitted radio signals includes:

the wireless unit adjusting the relative amplitudes and relative phases of transmitted radio signals using a Self-Interference Cancelling (SIC) precoder.

10. The method of claim 9, wherein the step of wireless unit adjusting the relative amplitudes and relative phases of transmitted radio signals further includes:

the wireless unit determining the SIC precoder based on an estimate of Self Interference (SI) channel matrix for the pre-determined frequency band, wherein the SI channel matrix includes a plurality of matrix elements, and wherein a matrix element in the i^th row and j^th column of the SI channel matrix represents a channel response from the j^th transmit antenna in the plurality of antennas to the i^th receive antenna at a given frequency in the pre-determined frequency band corresponding to a communication channel established between the j^th transmit antenna and the i^th receive antenna; and

applying the SIC precoder to each transmission in the pre-determined frequency band from each transmit antenna, thereby shaping all transmissions to collectively produce the substantial null at each receive antenna upon being transmitted from the corresponding transmit antennas.

11. The method of claim 10, wherein the step of wireless unit determining the SIC precoder includes one of the following:

the wireless unit determining the SIC precoder as those eigenvectors of a projection matrix K₁(f)≡

I−

Ĥ

_SI^H(f)(Ĥ

_SI(f)Ĥ

_SI^H(f))<sup>−

1</sup>Ĥ

_SI(f) that correspond to non-zero eigenvalues of K₁(f), wherein “

I”

is an identity matrix, Ĥ

_SI(f) is the estimate of the SI channel matrix H_SI(f), Ĥ

_SI^H(f) is a Hermitian transpose of Ĥ

_SI(f), and f is the given frequency in the predetermined frequency band;

the wireless unit determining the SIC precoder as those eigenvectors of K₂(f)≡

Ĥ

_SI^H(f)(Ĥ

_SI(f)Ĥ

_SI^H(f))<sup>−

1</sup>Ĥ

_SI(f) that correspond to the zero eigenvalue of K₂(f); and

the wireless unit determining the SIC precoder as a matrix whose columns represent a set of orthonormal basis vectors of the right null space of Ĥ

_SI(f).

12. The method of claim 10, further comprising the steps of:

the wireless unit transmitting a first pre-determined number of pilot signals, wherein each pilot signal in the first pre-determined number of pilot signals is transmitted in the predetermined frequency band utilizing a first subset of the transmit antennas, wherein the first subset includes at least one of the transmit antennas;

the wireless unit determining an initial version of the estimate of the SI channel matrix based on receptions of the first pre-determined number of pilot signals at each receive antenna; and

the wireless unit determining an initial version of the precoder based on the initial version of the estimate of the SI channel matrix.

13. The method of claim 12, further comprising the step of:

the wireless unit iteratively refining the initial versions of the estimate of the SI channel matrix and the precoder until a pre-determined criterion is satisfied.

14. The method of claim 13, wherein the step of wireless unit iteratively refining the initial versions of the estimate of the SI channel matrix and the precoder includes:

the wireless unit applying the initial version of the precoder to a second predetermined number of pilot signals;

the wireless unit transmitting the precoder-applied second pre-determined number of pilot signals in the pre-determined frequency band utilizing a second subset of the transmit antennas, wherein the second subset of the transmit antennas includes less than or equal to all transmit antennas;

the wireless unit determining an updated version of the estimate of the SI channel matrix based on receptions of the second pre-determined number of pilot signals at each receive antenna;

the wireless unit determining an updated version of the precoder based on the updated version of the estimate of the SI channel matrix; and

until the pre-determined criterion is satisfied, the wireless unit iteratively refining the updated versions of the estimate of the SI channel matrix and the precoder through transmissions and receptions of the second pre-determined number of pilot signals having been applied the most-recently updated version of the precoder prior to each iteration-specific transmission.

15. The method of claim 14, wherein the pre-determined criterion includes one of the following:

a pre-determined number of iterations being reached;

a change in a measure of a channel estimation error based on receptions of the second pre-determined number of pilot signals at each receive antenna being smaller than a pre-determined threshold prior to next iteration; and

a maximum transmit power level being reached for each pilot signal in the second pre-determined number of pilot signals.

16. The method of claim 14, further comprising:

the wireless unit increasing the transmit power level of each pilot signal in the second pre-determined number of pilot signals prior to each iteration.

17. The method of claim 9, wherein the wireless communication unit is configured to perform Multi-User (MU) Multiple-Input Multiple-Output (MIMO) transmissions to a plurality of user devices, and wherein the method further comprises the steps of:

the wireless unit determining a user device-specific MU precoder for the predetermined frequency band using the SIC precoder for the pre-determined frequency band; and

the wireless unit applying the user device-specific MU precoder and the SIC precoder to each user device-specific transmission therefrom in the pre-determined frequency band.

18. The method of claim 17, wherein the step of wireless unit determining the user-device specific MU precoder includes:

the wireless unit determining a user-device specific channel response matrix for the pre-determined frequency band for at least one of the plurality of user devices, wherein each user-device specific channel response matrix includes a corresponding plurality of matrix elements, and wherein a matrix element in the x^th row and y^th column of the user-device specific channel response matrix represents a channel response from the y^th transmit antenna of the wireless unit to the x^th receive antenna of the corresponding user device at a given frequency in the pre-determined frequency band, corresponding to a communication channel established between the y^th transmit antenna of the wireless unit and the x^th receive antenna of the corresponding user device; and

the wireless unit combining at least one user-device specific channel response matrix with the SIC precoder as part of determining a corresponding user device-specific MU precoder.

19. The method of claim 1, wherein the method further comprises:

the wireless unit receiving a total of n_S number of Multiple-Input Multiple-Output (MIMO) data streams from a plurality of user devices using receiver combining weights with an N_R number of receive antennas, wherein N_R>

n_S;

the wireless unit computing a modified channel matrix taking into account the receiver combining weights;

the wireless unit determining a Self-Interference Cancelling (SIC) precoder based on the modified channel matrix; and

the wireless unit simultaneously transmitting a number of transmit data streams through the SIC precoder.

20. The method of claim 1, wherein the wireless unit configures all transmit antennas to collectively digitally place the substantial null at each receive antenna.

21. In a method to provide self-interference cancellation during full-duplex communication in a pre-determined frequency band using a multi-antenna wireless system that simultaneously transmits and receives signals during the full-duplex communication using one or more antennas thereof, the improvement comprising:

adjusting the relative amplitudes and relative phases of signals transmitted in the pre-determined frequency band through the transmitting antennas of the wireless system in such a manner as to place a substantial null at each receiving antenna of the wireless system receiving at least a portion of the transmitted signals.

22. A wireless communication unit having a plurality of antennas to provide full-duplex communication at a given frequency in a pre-determined frequency band, wherein the wireless communication unit is configured to perform the following:

receive one or more receive data streams in the pre-determined frequency band utilizing a first subset of the plurality of antennas, wherein the first subset includes at least one antenna from the plurality of antennas as a receive antenna;

simultaneously transmit one or more transmit data streams in the pre-determined frequency band utilizing a second subset of the plurality of antennas as transmit antennas, wherein the subset includes less than or equal to the total number of antennas in the plurality of antennas; and

adjust the relative amplitudes and relative phases of radio signals carrying the transmit data streams that are transmitted through the transmit antennas in the predetermined frequency band, thereby configuring all transmit antennas to collectively place a substantial null at each receive antenna when transmitting in the pre-determined frequency band.

23. The wireless unit of claim 22, wherein the wireless unit is configured to adjust the relative amplitudes and relative phases of transmitted radio signals using a digital Self-Interference Cancelling (SIC) precoder.

24. The wireless unit of claim 22, wherein at least two antennas from the plurality of antennas are at geographically-distributed locations.