# US 2018/0027437 A1 · Channel estimation enhancement

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- Number: US 2018/0027437 A1
- Document ID: US20180027437A1
- Status: Published application
- Kind: A1
- Application number: 15/389,337
- Filed: 2016-12-22
- Published: 2018-01-25
- Earliest claimed: 2016-07-22
- Assignees: QUALCOMM Incorporated
- Applicants: QUALCOMM Incorporated
- Inventors: Pavan Kumar Vitthaladevuni; June Namgoong; Joseph Binamira Soriaga; Jay Kumar Sundararajan
- Web page: https://patentgrep.com/patent/US20180027437A1

## CPC

- H04W 24/10: Scheduling measurement reports {; Arrangements for measurement reports}
- H04B 17/318: Received signal strength
- H04B 17/347: {Path loss}
- H04L 1/0026: {Transmission of channel quality indication}
- H04L 1/1887: {Scheduling and prioritising arrangements}
- H04L 1/20: using signal quality detector
- H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)}
- H04L 5/006: {Quality of the received signal, e.g. BER, SNR, water filling}
- H04L 25/0224: {using sounding signals}
- H04W 52/10: Open loop power control
- H04W 52/146: {Uplink power control}
- H04W 52/242: {taking into account path loss}
- H04W 52/325: {Power control of control or pilot channels}
- H04W 52/343: {taking into account loading or congestion level}
- H04W 52/38: TPC being performed in particular situations
- H04W 72/0446: Resources in time domain, e.g. slots or frames
- H04W 72/20: Control channels or signalling for resource management
- H04W 72/542: using measured or perceived quality
- H04W 52/383: {power control in peer-to-peer links}
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Aspects of the present disclosure provide for enhanced channel estimation in a wireless communication network. Uplink channel estimation may be enhanced by increasing the uplink transmit power of an uplink reference signal. For example, the uplink transmit power may be increased by multiplying a measured downlink path loss by a predetermined factor to produce an increased downlink path loss and calculating the uplink transmit power based on the increased downlink path loss. Downlink channel estimation may be enhanced by increasing a number of tones on a downlink reference signal assigned to a scheduled entity relative to the number of tones assigned to other scheduled entities.

## Claims

### Claim 1

A method of channel estimation in a wireless communication network, the method comprising:
measuring a downlink path loss to produce a measured downlink path loss;
multiplying the measured downlink path loss by a predetermined factor to produce an increased downlink path loss having a value greater than the measured downlink path loss when the measured downlink path loss is greater than a threshold;
calculating an uplink transmit power using the increased downlink path loss; and
transmitting an uplink reference signal with the uplink transmit power to enable an uplink channel estimation.

### Claim 2 (depends on 1)

The method of claim 1, wherein multiplying the measured downlink path loss by the predetermined factor to produce the increased downlink path loss further comprises:
multiplying the measured downlink path loss by a path loss compensation factor having a value greater than one to produce the increased downlink path loss.

### Claim 3 (depends on 2)

The method of claim 2, further comprising:
setting the value of the path loss compensation factor based on resource utilization information indicating an amount of resources in use in the wireless communication network.

### Claim 4 (depends on 2)

The method of claim 2, wherein calculating the uplink transmit power further comprises:
calculating the uplink transmit power for a Sounding Reference Signal (SRS).

### Claim 5 (depends on 4)

The method of claim 4, wherein transmitting the uplink reference signal further comprises:
transmitting the SRS with the uplink transmit power for the SRS.

### Claim 6 (depends on 1)

The method of claim 1, wherein measuring the downlink path loss to produce the measured downlink path loss further comprises:
measuring the downlink path loss based on a downlink reference signal.

### Claim 7 (depends on 6)

The method of claim 6, wherein measuring the downlink path loss based on the downlink reference signal further comprises:
receiving a channel state information reference signal;
measuring a reference signal received power of the channel state information reference signal; and
subtracting the reference signal received power from a known downlink transmit power to produce the measured downlink path loss.

### Claim 8 (depends on 6)

The method of claim 6, wherein measuring the downlink path loss based on the downlink reference signal further comprises:
receiving a downlink demodulation reference signal;
measuring a reference signal received power of the downlink demodulation reference signal; and
subtracting the reference signal received power from a known downlink transmit power to produce the measured downlink path loss.

### Claim 9 (depends on 6)

The method of claim 6, wherein:
the downlink reference signal comprises a plurality of tones;
each of the plurality of tones is assigned to a respective scheduled entity of a set of scheduled entities;
each scheduled entity of the set of scheduled entities is assigned a respective number of the plurality of tones; and
the number of tones assigned to at least one scheduled entity of the set of scheduled entities is different than the number of tones assigned to other scheduled entities of the set of scheduled entities.

### Claim 10 (depends on 9)

The method of claim 9, further comprising:
estimating, by a select scheduled entity of the set of scheduled entities, one or more parameters of a downlink channel between a scheduling entity and the select scheduled entity using the number of tones in the downlink reference signal assigned to the select scheduled entity.

### Claim 11 (depends on 10)

The method of claim 10, wherein the number of tones assigned to the select scheduled entity is greater than the number of tones assigned to at least one other scheduled entity of the set of scheduled entities.

### Claim 12 (depends on 10)

The method of claim 10, wherein estimating the one or more parameters of the downlink channel further comprises:
calculating channel state information for the downlink channel using the number of tones in the downlink reference signal assigned to the select scheduled entity; and
transmitting the channel state information to the scheduling entity.

### Claim 13

An apparatus for wireless communication, comprising:
a processor;
a transceiver communicatively coupled to the processor; and
a memory communicatively coupled to the processor,
wherein the processor is configured to:
measure a downlink path loss to produce a measured downlink path loss;
multiply the measured downlink path loss by a predetermined factor to produce an increased downlink path loss having a value greater than the measured downlink path loss when the measured downlink path loss is greater than a threshold;
calculate an uplink transmit power using the increased downlink path loss; and
transmit an uplink reference signal with the uplink transmit power to enable an uplink channel estimation.

### Claim 14 (depends on 13)

The apparatus of claim 13, wherein to measure the downlink path loss to produce the measured downlink path loss, the processor is further configured to:
measure the downlink path loss based on a downlink reference signal.

### Claim 15 (depends on 14)

The apparatus of claim 14, wherein to measure the downlink path loss based on the downlink reference signal, the processor is further configured to:
receive a channel state information reference signal;
measure a reference signal received power of the channel state information reference signal; and
subtract the reference signal received power from a known downlink transmit power to produce the measured downlink path loss.

### Claim 16 (depends on 14)

The apparatus of claim 14, wherein to measure the downlink path loss based on the downlink reference signal, the processor is further configured to:
receive a downlink demodulation reference signal;
measure a reference signal received power of the downlink demodulation reference signal; and
subtract the reference signal received power from a known downlink transmit power to produce the measured downlink path loss.

### Claim 17 (depends on 14)

The apparatus of claim 14, wherein:
the downlink reference signal comprises a plurality of tones;
each of the plurality of tones is assigned to a respective scheduled entity of a set of scheduled entities;
each scheduled entity of the set of scheduled entities is assigned a respective number of the plurality of tones; and
the number of tones assigned to at least one scheduled entity of the set of scheduled entities is different than the number of tones assigned to other scheduled entities of the set of scheduled entities.

### Claim 18

A method for channel estimation in a wireless communication network, the method comprising:
measuring an uplink path loss for a scheduled entity of a set of scheduled entities;
generating a downlink reference signal including a plurality of tones;
assigning each of the plurality of tones to a respective scheduled entity of the set of scheduled entities, wherein a number of the plurality of tones assigned to the scheduled entity of the set of scheduled entities is different than the number of the plurality of tones assigned to at least one other scheduled entity of the set of scheduled entities based on the uplink path loss; and
transmitting the downlink reference signal including the plurality of tones to the set of scheduled entities to enable downlink channel estimations at each of the scheduled entities of the set of scheduled entities.

### Claim 19 (depends on 18)

The method of claim 18, wherein the number of the plurality of tones assigned to the scheduled entity of the set of scheduled entities is greater than the number of the plurality of tones assigned to the at least one other scheduled entity of the set of scheduled entities when the uplink path loss for the scheduled entity is greater than a threshold and the uplink path loss for the at least one other scheduled entity is less than the threshold, the method further comprising
signaling an assignment of the plurality of tones to the scheduled entity.

### Claim 20 (depends on 18)

The method of claim 18, wherein the number of the plurality of tones assigned to the scheduled entity of the set of scheduled entities is less than the number of the plurality of tones assigned to the at least one other scheduled entity of the set of scheduled entities when the uplink path loss for the scheduled entity is less than a threshold and the uplink path loss for the at least one other scheduled entity is greater than the threshold, the method further comprising
signaling an assignment of the plurality of tones to the scheduled entity.

### Claim 21 (depends on 18)

The method of claim 18, wherein measuring the uplink path loss further comprises:
measuring a reference signal received power of an uplink reference signal received from the scheduled entity of the set of scheduled entities; and
subtracting the reference signal received power from a known uplink transmit power of the scheduled entity to determine the uplink path loss.

### Claim 22 (depends on 21)

The method of claim 21, wherein measuring the reference signal received power further comprises:
receiving a sounding reference signal; and
measuring the reference signal received power of the sounding reference signal.

### Claim 23 (depends on 22)

The method of claim 22, wherein receiving the sounding reference signal further comprises:
receiving the sounding reference signal transmitted with an increased uplink transmit power calculated using an increased downlink path loss relative to a measured downlink path loss.

### Claim 24 (depends on 23)

The method of claim 23, further comprising:
estimating one or more parameters of an uplink channel between a scheduling entity and the scheduled entity using the sounding reference signal.

### Claim 25 (depends on 23)

The method of claim 23, further comprising:
estimating one or more parameters of a downlink channel between a scheduling entity and the scheduled entity using the sounding reference signal.

### Claim 26

An apparatus for wireless communication, comprising:
a processor;
a transceiver communicatively coupled to the processor; and
a memory communicatively coupled to the processor,
wherein the processor is configured to:
measure an uplink path loss for a scheduled entity of a set of scheduled entities;
generate a downlink reference signal including a plurality of tones;
assign each of the plurality of tones to a respective scheduled entity of the set of scheduled entities, wherein a number of the plurality of tones assigned to the scheduled entity of the set of scheduled entities is different than the number of the plurality of tones assigned to at least one other scheduled entity of the set of scheduled entities based on the uplink path loss; and
transmit the downlink reference signal including the plurality of tones to the set of scheduled entities to enable downlink channel estimations at each of the scheduled entities of the set of scheduled entities.

### Claim 27 (depends on 26)

The apparatus of claim 26, wherein to measure the uplink path loss, the processor is further configured to:
measure a reference signal received power of an uplink reference signal received from the scheduled entity of the set of scheduled entities; and
subtract the reference signal received power from a known uplink transmit power of the scheduled entity to determine the uplink path loss.

### Claim 28 (depends on 27)

The apparatus of claim 27, wherein to measure the reference signal received power, the processor is further configured to:
receive a sounding reference signal; and
measure the reference signal received power of the sounding reference signal.

### Claim 29 (depends on 28)

The apparatus of claim 28, wherein to receive the sounding reference signal, the processor is further configured to:
receive the sounding reference signal transmitted with an increased uplink transmit power calculated using an increased downlink path loss relative to a measured downlink path loss.