# US 8,787,480 B2 · Method of determining channel state information

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- Number: US 8,787,480 B2
- Document ID: US8787480B2
- Status: Granted
- Kind: B2
- Application number: 13/217,043
- Filed: 2011-08-24
- Published: 2013-02-28
- Granted: 2014-07-22
- Earliest claimed: 2011-08-24
- Assignees: BlackBerry Limited
- Applicants: Chandra-Prakash Gupta; Martin Kosakowski; Ernst Slawomir Zielinski
- Inventors: Chandra-Prakash Gupta; Martin Kosakowski; Ernst Slawomir Zielinski
- Web page: https://patentgrep.com/patent/US8787480B2

## CPC

- H04L 25/03: Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04B 7/063: {Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection}
- H04B 7/0639: {Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection}
- H04L 1/0031: {Multiple signaling transmission (H04L1/1664, F15 take precedence)}
- H04L 1/0026: {Transmission of channel quality indication}
- H04L 5/0023: {Time-frequency-space}
- H04L 5/0057: {Physical resource allocation for CQI}
- H04L 27/2647: {Arrangements specific to the receiver only (equalisation H04L27/01)}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04B: TRANSMISSION

## Abstract

A method for estimating channel state information (CSI) for a communication channel is disclosed. Theoretical channel capacities are calculated using combinations of rank indicator (RI) and precoding matrix index (PMI) values. A number of these theoretical channel capacities are selected and used for determining an optimum combination of channel quality indicator (CQI) values, RI values and PMI values. This combination of values is subsequently transmitted as CSI.

## Claims

### Claim 1

A method of estimating channel state information (CSI) for a communication channel comprising:
calculating a number of theoretical channel capacities using a plurality of combinations of values of an indicator of rank and an indicator of precoding;
selecting a plurality M of said theoretical channel capacities and their associated values of the indicator of rank and indicator of precoding; and,
determining the optimum combination of values of an indicator of channel quality, the indicator of rank and indicator of precoding, from the selected M values of the indicator of rank and indicator of precoding.

### Claim 2 (depends on 1)

The method of claim 1, wherein the step of calculating theoretical channel capacities comprises calculating effective channel matrices from said combinations of values of the indicator of rank and indicator of precoding.

### Claim 3 (depends on 1)

The method of claim 1, wherein the step of calculating theoretical channel capacities is dependent on post-detector SNR values.

### Claim 4 (depends on 1)

The method of claim 1, wherein the M theoretical channel capacities are the largest M theoretical channel capacities.

### Claim 5 (depends on 1)

The method of claim 1, wherein the M theoretical channel capacities are the largest M/N capacities from each rank, where N≦M.

### Claim 6 (depends on 1)

The method of claim 1, wherein the M theoretical channel capacities includes the largest M-N capacities from a specified rank and the remaining largest N capacities from adjacent ranks, where N<M.

### Claim 7 (depends on 1)

The method of claim 1, wherein M is greater than 1 and less than the total number of theoretical channel capacities.

### Claim 8 (depends on 1)

The method of claim 1, wherein determining the optimum combination of values of the indicator of channel quality, indicator of rank and indicator of precoding comprises performing a modulation coding scheme (MCS) search and finding the values of the indicator of channel quality, indicator of rank and indicator of precoding associated with the maximum data rate and an error rate below a predetermined threshold.

### Claim 9 (depends on 8)

The method of claim 8, wherein the MCS search is performed on the M theoretical channel capacities in decreasing order.

### Claim 10 (depends on 1)

The method of claim 1, wherein the step of calculating theoretical channel capacities is terminated if the highest theoretical channel capacity associated with rank i+1 is lower than the highest theoretical channel capacity associated with rank i.

### Claim 11 (depends on 1)

The method of claim 1, wherein the step of calculating theoretical channel capacities comprises utilising pre-calculated results stored in a look-up table.

### Claim 12 (depends on 1)

The method of claim 1, further comprising the step of transmitting the determined optimum combination of values.

### Claim 13 (depends on 1)

A method according to claim 1, when implemented by a user equipment connected to a wireless LTE network.

### Claim 14 (depends on 1)

The method of claim 1, wherein the indicator of rank is rank indication (RI), the indicator of precoding is a precoding matrix index (PMI) and the indicator of channel quality is channel quality indicator (CQI).

### Claim 15

A user equipment comprising:
one or more processors configured to:
calculate a number of theoretical channel capacities using a plurality of combinations of values of an indicator of rank and an indicator of precoding;
select a plurality M of said theoretical channel capacities and their associated values of the indicator of rank and indicator of precoding; and,
determine the optimum combination of values of an indicator of channel quality, the indicator of rank and indicator of precoding, from the selected M values of the indicator of rank and indicator of precoding.

### Claim 16 (depends on 15)

The user equipment of claim 15, wherein the one or more processors configured to calculate theoretical channel capacities comprises the one or more processors configured to calculate effective channel matrices from said combinations of values of the indicator of rank and indicator of precoding.

### Claim 17 (depends on 15)

The user equipment of claim 15, wherein the step of calculating theoretical channel capacities is dependent on post-detector SNR values.

### Claim 18 (depends on 15)

The user equipment of claim 15, wherein the M theoretical channel capacities are the largest M theoretical channel capacities.

### Claim 19 (depends on 15)

The user equipment of claim 15, wherein the M theoretical channel capacities are the largest M/N capacities from each rank, where N≦M.

### Claim 20 (depends on 15)

The user equipment of claim 15, wherein the M theoretical channel capacities includes the largest M-N capacities from a specified rank and the remaining largest N capacities from adjacent ranks, where N<M.

### Claim 21 (depends on 15)

The user equipment of claim 15, wherein M is greater than 1 and less than the total number of theoretical channel capacities.

### Claim 22 (depends on 15)

The user equipment of claim 15, wherein the one or more processors configured to determine the optimum combination of values of the indicator of channel quality, indicator of rank and indicator of precoding comprises the one or more processors configured to perform a modulation coding scheme (MCS) search and finding the values of the indicator of channel quality, indicator of rank and indicator of precoding associated with the maximum data rate and an error rate below a predetermined threshold.

### Claim 23 (depends on 22)

The user equipment of claim 22, wherein the MCS search is performed on the M theoretical channel capacities in decreasing order.

### Claim 24 (depends on 15)

The user equipment of claim 15, wherein the one or more processors configured to calculate theoretical channel capacities is terminated if the highest theoretical channel capacity associated with rank i+1 is lower than the highest theoretical channel capacity associated with rank i.

### Claim 25 (depends on 15)

The user equipment of claim 15, wherein the step of calculating theoretical channel capacities comprises utilising pre-calculated results stored in a look-up table.

### Claim 26 (depends on 15)

The user equipment of claim 15, the one or more processors further configured to transmit the determined optimum combination of values.

### Claim 27 (depends on 15)

The user equipment of claim 15, wherein the indicator of rank is rank indication (RI), the indicator of precoding is a precoding matrix index (PMI) and the indicator of channel quality is channel quality indicator (CQI).