# US 2014/0153510 A1 · Interference Management in Wireless Multi-Access Communication Networks

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- Number: US 2014/0153510 A1
- Document ID: US20140153510A1
- Status: Published application
- Kind: A1
- Application number: 14/093,093
- Filed: 2013-11-29
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: Avago Technologies General IP (Singapore) Pte. Ltd.
- Applicants: Broadcom Corporation
- Inventors: Krishna Srikanth GOMADAM; Djordje TUJKOVIC
- Web page: https://patentgrep.com/patent/US20140153510A1

## CPC

- H04L 5/0073: {Allocation arrangements that take into account other cell interferences}
- 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
- H04B 7/0456: Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
- H04B 7/0634: {Antenna weights or vector/matrix coefficients}
- H04B 7/0639: {Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04B: TRANSMISSION

## Abstract

Embodiments provide systems and methods for interference management in wireless multi-access communication networks, and more particularly systems and methods to enable reduction and/or suppression of interference. Embodiments for interference reduction include, without limitation, systems and methods to enable interference alignment, interference avoidance, and/or joint transmission to a user equipment (UE). Embodiments for enabling suppression of interference include, without limitation, systems and methods for feedback (from a UE to a network) or feedforward (from the network to the UE) signaling to enable interference estimation at the network/UE.

## Claims

### Claim 1

A user equipment (UE), comprising:
a channel estimation module configured to generate first and second channel estimates from first and second interfering cells;
an interference management module configured to compute first and second precoder matrix indicators (PMIs) for the first and second interfering cells respectively based on the first and second channel estimates, wherein the first and second PMIs substantially align first and second interfering signals received from the first and second interfering cells; and
one or more antennas configured to signal the first and second PMIs to a network entity.

### Claim 2 (depends on 1)

The UE of claim 1, wherein the interference management module is further configured to select the first and second interfering cells from multiple available cells.

### Claim 3 (depends on 2)

The UE of claim 2, wherein the interference management module is configured to compute the first and second PMIs according to:
(
i
opt
,
j
opt
)
=
arg


max
i
,
j

〈
H
2

W
i

H
2

W
i

,
H
3

W
j

H
3

W
j

〉
where iopt and jopt correspond respectively to indices of the first and second PMIs, H2 corresponds to the first channel estimate from the first interfering cell, H3 corresponds to the second channel estimate from the second interfering cell, Wi corresponds to the first PMI, and Wj corresponds to the second PMI, and denotes a dot-product operation.

### Claim 4 (depends on 2)

The UE of claim 2, wherein the interference management module is further configured to select a serving cell of the UE and the first and second interfering cells from the multiple available cells.

### Claim 5 (depends on 4)

The UE of claim 4, wherein the interference management module is further configured to select the serving cell and the first and second interfering cells to increase a data throughput to the UE.

### Claim 6 (depends on 4)

The UE of claim 4, wherein the interference management module is further configured to compute a PMI for the serving cell and the first and second PMIs according to:
(
i
opt
,
j
opt
,
k
opt
)
=
arg


max
i
,
j
,
k

logdet

(
I
+
H
1

W
i

W
i
*

H
1
*

(
H
2

W
j

W
j
*

H
2
*
+
H
3

W
k

W
k
*

H
3
*
+
I
)
-
1
)
where iopt, jopt, kopt correspond respectively to indices of the PMI and the first and second PMIs, I corresponds to an identity matrix, H1 corresponds to a channel estimate from the serving cell, H2 corresponds to the first channel estimate from the first interfering cell, H3 corresponds to the second channel estimate from the second interfering cell, Wi corresponds to the PMI for the serving cell, Wj corresponds to the first PMI, Wk corresponds to the second PMI, and det( ) denotes a matrix determinant operation.

### Claim 7 (depends on 1)

The UE of claim 1, wherein the interference management module is further configured to compute at least one of the first and second PMIs to reduce interference from at least one of the first and second interfering cells.

### Claim 8

A user equipment (UE), comprising:
a channel estimation module configured to generate channel estimates from multiple available cells;
an interference management module configured to select a cell combination from the multiple available cells based at least in part on the channel estimates, the cell combination configured to increase a signal strength of a joint transmission from the cell combination to the UE; and
one or more antennas configured to signal the cell combination to a network entity.

### Claim 9 (depends on 8)

The UE of claim 8, wherein the interference management module is further configured to select a joint transmission level determining a number of cells of the multiple available cells participating in the joint transmission to the UE.

### Claim 10 (depends on 9)

The UE of claim 9, wherein a size of the cell combination is equal to the joint transmission level.

### Claim 11 (depends on 9)

The UE of claim 9, wherein the interference management module is further configured to determine a joint precoder matrix indicator (PMI) for the cell combination.

### Claim 12 (depends on 11)

The UE of claim 11, wherein the joint PMI maximizes the signal strength of the joint transmission from the cell combination to the UE.

### Claim 13 (depends on 11)

The UE of claim 11, wherein the cell combination includes first and second cells of the multiple available cells, and wherein the interference management is further configured to select the cell combination and the joint PMI according to:
(
i
opt
,
j
opt
,
k
opt
)
=
arg


max
i
,
j
,
k


[
H
i
H
j
]

W
k

2
where iopt and jopt correspond respectively to indices of the first and second cells, kopt corresponds to an index of the joint PMI, Hi corresponds to a first channel estimate from the first cell, Hj corresponds to a second channel estimate from the second cell, and Wk corresponds to the joint PMI.

### Claim 14

A user equipment (UE), comprising:
a channel estimation module configured to generate a channel estimate from a cell;
an interference management module configured to decompose the channel estimate to generate a left singular matrix and to quantize the left singular matrix to generate a quantized left singular matrix; and
one or more antennas configured to signal the quantized left singular matrix to a network entity.

### Claim 15 (depends on 14)

The UE of claim 14, wherein the quantized left singular matrix reduces an error between the channel estimate and a network version of the channel estimate.

### Claim 16 (depends on 14)

The UE of claim 14, wherein the interference management module is configured to generate the quantized left singular matrix according to:
U
opt
=
arg

min
U
∈
C


H
-
U
*

S


N


R

(
cqi
)
*
V
*

where Uopt corresponds to the quantized left singular matrix, C corresponds to a set of possible left singular matrix quantizations of the left singular matrix, U corresponds to a left singular matrix quantization from the set C, H corresponds to the channel estimate, SNR(CQI) corresponds to an estimate of signal-to-noise ratio (SNR) at the UE, and V corresponds to a right singular matrix of the channel estimate.

### Claim 17

A user equipment (UE), comprising:
an interference management module configured to receive an interference correlation matrix index from a network entity, and compute an interference covariance matrix based at least in part on the interference correlation matrix index; and
a demodulator configured to demodulate a desired signal using the interference covariance matrix.

### Claim 18 (depends on 17)

The UE of claim 17, wherein the interference management module is further configured to determine an interference correlation matrix based on the interference correlation matrix index; generate a magnitude matrix from a noise power estimate; and compute the interference covariance matrix using the interference correlation matrix and the magnitude matrix.

### Claim 19 (depends on 18)

The UE of claim 18, wherein the interference correlation matrix index specifies a correlation coefficient of the interference correlation matrix.

### Claim 20 (depends on 17)

The UE of claim 17, wherein the UE comprises a plurality of antennas, and wherein the interference correlation matrix index is selected based on a physical structure of the plurality of antennas.