# US 2008/0188186 A1 · Apparatus and method for transmitting channel sounding signal in wireless communication system

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- Number: US 2008/0188186 A1
- Document ID: US20080188186A1
- Status: Published application
- Kind: A1
- Application number: 12/012,382
- Filed: 2008-01-31
- Published: 2008-08-07
- Earliest claimed: 2007-02-05
- Assignees: Samsung Electronics Co., Ltd.; Korea University Industrial & Academic Collaboration Foundation
- Inventors: Keun-Chul Hwang; Sung-Ho Lee; Soon-Young Yoon; In-Kyu Lee; Seok-Hwan Park
- Web page: https://patentgrep.com/patent/US20080188186A1

## CPC

- H04B 7/0808: {comparing all antennas before reception}
- H04L 25/0224: {using sounding signals}
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Provided is an apparatus and method for transmitting a channel sounding signal from a user terminal in a multiple antenna system. In the method, a channel for each of a plurality of antennas is estimated. The receiving signal power of each of the antennas is calculated using the channel information obtained through the channel estimation. The antenna with the highest RX signal power is selected. Therefore, it is possible to enhance the signal reception performance of the user terminal.

## Claims

### Claim 1

A method for transmitting a channel sounding signal from a user terminal in a multiple antenna system, the method comprising:
estimating a channel for each of a plurality of antennas;
calculating a receiving (RX) signal power of each of the antennas by using channel information obtained through the channel estimation; and
selecting the antenna with a highest RX signal power.

### Claim 2 (depends on 1)

The method of claim 1, further comprising transmitting a channel sounding signal to a base station through the selected antenna.

### Claim 3 (depends on 2)

The method of claim 2, further comprising allocating a sounding channel for transmission of the channel sounding signal from the base station.

### Claim 4 (depends on 1)

The method of claim 1, wherein the antenna with the highest RX signal power is selected using the following equation:
k
=
arg max
i
=
1
,
…

,
M
r


Hw
i

2
where Mr denotes a total number of antennas of the user terminal, wi denotes a beamforming weight of an ith antenna, H denotes a channel matrix, and |Hwi|2 denotes the RX signal power of the ith antenna which is calculated using the channel matrix H and the beamforming weight wi of the ith antenna.

### Claim 5 (depends on 4)

The method of claim 4, wherein the beamforming weight is calculated using the following equation:
w
i
=
h
*

h
i

where hi denotes the channel information of the ith antenna obtained through the channel estimation and * denotes a complex conjugate transpose.

### Claim 6 (depends on 1)

The method of claim 1, wherein the channel is estimated using a pilot signal included in a downlink signal.

### Claim 7

An apparatus for transmitting a channel sounding signal from a user terminal in a multiple antenna system, the apparatus comprising:
a channel estimator for estimating a channel for each of a plurality of antennas;
a receiving (RX) signal power calculator for calculating a RX signal power of each of the antennas by using channel information obtained through the channel estimation; and
an antenna selector for selecting an antenna with the highest RX signal power.

### Claim 8 (depends on 7)

The apparatus of claim 7, further comprising a transmitting TX/RX switch for transmitting a channel sounding signal to a base station through the selected antenna.

### Claim 9 (depends on 8)

The apparatus of claim 8, wherein the TX/RX switch transmits the channel sounding signal over a sounding channel allocated by the base station.

### Claim 10 (depends on 8)

The apparatus of claim 8, wherein the TX/RX switch comprises:
an antenna switch for outputting a data signal received from a baseband modem to a switch connected to the antenna for transmission and reception of the data signal, and outputting the channel sounding signal received from the baseband modem to the switch connected to the selected antenna; and
switches for the respective antennas for outputting a signal received from the antenna switch to a connected antenna, and outputting the signal from the connected antenna to the baseband modem.

### Claim 11 (depends on 7)

The apparatus of claim 7, wherein the antenna selector selects the antenna using the following equation:
k
=
arg max
i
=
1
,
…

,
M
r


Hw
i

2
where Mr denotes a total number of antennas of the user terminal, wi denotes a beamforming weight of a ith antenna, H denotes a channel matrix, and |Hwi|2 denotes the RX signal power of the ith antenna which is calculated using the channel matrix H and the beamforming weight wi of the ith antenna.

### Claim 12 (depends on 11)

The apparatus of claim 11, wherein the beamforming weight is calculated using the following equation:
w
i
=
h
i
*

h
i

where hi denotes the channel information of the ith antenna obtained through the channel estimation and * denotes a complex conjugate transpose.

### Claim 13 (depends on 7)

The apparatus of claim 7, wherein the channel estimator estimates the channel using a pilot signal included in a downlink signal.

### Claim 14

A method for transmitting data from a base station in a multiple antenna system, the method comprising:
receiving a channel sounding signal transmitted from user terminals through an antenna with a highest receiving (RX) signal power among a plurality of user terminal antennas;
estimating a channel between a channel sounding signal transmitting antenna of each user terminal and base station antennas by using the received channel sounding signal from each user terminal; and
calculating a beamforming weight for each user terminal by using channel information of each antenna obtained through the channel estimation.

### Claim 15 (depends on 14)

The method of claim 14, further comprising multiplying a transmitting (TX) data signal by the calculated beamforming weight and transmitting a resulting signal to the user terminals.

### Claim 16 (depends on 14)

The method of claim 14, wherein the beamforming weight is calculated using the following equation:
w
i
=
h
i
*

h
i

where hi denotes the channel information of a ith antenna obtained through the channel estimation and * denotes a complex conjugate transpose.

### Claim 17 (depends on 14)

The method of claim 14, further comprising selecting the user terminals to be provided with a service in a current frame, among user terminals located in a service area, by using the channel information of each user terminal obtained from the channel estimation.

### Claim 18 (depends on 17)

The method of claim 17, wherein the user terminals to be provides with the service are selected using the following equation:
p
_
=
arg max
i
=
1
,
…

,
M
r

tr

(
(
H
p

H
p
H
)
-
1
)
where P denotes a user terminal set of all possible combinations including a predetermined number of user terminals among all the user terminals located in the service area, p denotes the selected user terminal set, Hp denotes a matrix including the channel information of the user terminals included in the user terminal set, and tr( ) denotes a trace function for obtaining a sum of all diagonal elements of a matrix in ( ).

### Claim 19 (depends on 14)

The method of claim 14, further comprising allocating the user terminals a sounding channel for transmission of the channel sound signal.

### Claim 20

An apparatus for transmitting data from a base station in a multiple antenna system, the apparatus comprising:
a transmitting (TX) and receiving (RX) switch for receiving a channel sounding signal transmitted from user terminals through an antenna with a highest RX signal power among a plurality of user terminal antennas;
a channel estimator for estimating a channel between a channel sounding signal transmitting antenna of each user terminal and base station antennas by using the received channel sounding signal from each user terminal; and
a beamforming controller for calculating a beamforming weight for each user terminal by using channel information of each antenna obtained through the channel estimation.

### Claim 21 (depends on 20)

The apparatus of claim 20, further comprising a beamformer for multiplying a TX data signal by the calculated beamforming weight and transmitting a resulting signal to the user terminals through the TX/RX switch.

### Claim 22 (depends on 20)

The apparatus of claim 20, wherein the beamforming controller calculates the beamforming weight using the following equation:
w
i
=
h
i
*

h
i

where hi denotes the channel information of the ith antenna obtained through the channel estimation and * denotes a complex conjugate transpose.

### Claim 23 (depends on 20)

The apparatus of claim 20, further comprising a scheduler for selecting the user terminal to be provided with a service in a current frame, among user terminals located in a service area, by using the channel information of each user terminal obtained from the channel estimation.

### Claim 24 (depends on 23)

The apparatus of claim 23, wherein the scheduler selects the user terminals to be provided with the service, by using the following equation:
p
_
=
arg min
p
∈
P
r

tr

(
(
H
p

H
p
H
)
-
1
)
where P denotes a user terminal set of all possible combinations including a predetermined number of user terminals among all the user terminals located in the service area, p denotes the selected user terminal set, Hp denotes a matrix including the channel information of the user terminals included in the user terminal set, and tr( ) denotes a trace function for obtaining a sum of all diagonal elements of a matrix in ( ).

### Claim 25 (depends on 20)

The apparatus of claim 20, wherein the TX/RX switch receives the channel sounding signal over a sounding channel allocated to the user terminals.