# US 10,313,075 B2 · Method and apparatus for performing cell on/off operation in wireless communication system

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- Number: US 10,313,075 B2
- Document ID: US10313075B2
- Status: Granted
- Kind: B2
- Application number: 15/306,694
- Filed: 2015-04-28
- Published: 2017-02-16
- Granted: 2019-06-04
- Earliest claimed: 2014-04-28
- Assignees: LG Electronics Inc.
- Applicants: LG Electronics Inc.
- Inventors: Yunjung Yi; Joonkui Ahn; Kijun Kim; Byounghoon Kim
- Web page: https://patentgrep.com/patent/US10313075B2

## CPC

- 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)}
- H04W 8/005: {Discovery of network devices, e.g. terminals}
- H04W 52/0206: {in access points, e.g. base stations}
- H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal
- H04L 5/001: {the frequencies being arranged in component carriers}
- H04W 28/26: Resource reservation
- Y02D 30/70: in wireless communication networks
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

A method and apparatus for transmitting a periodic reference signal in a wireless communication system is provided. An evolved NodeB (eNB) configures a periodic reference signal, and transmits the periodic reference signal in a specific duration. The periodic reference signal may be a discovery reference signal (DRS) or a channel state information reference signal (CSI RS). The periodic reference signal may be transmitted flexibly or transmitted by performing listen-before-talk (LBT) with reservation of transmission of the periodic reference signal.

## Claims

### Claim 1

A method for transmitting, by an evolved NodeB (eNB) which operates in LTE in an unlicensed (LTE-U) spectrum, a discovery reference signal (DRS) in a wireless communication system, the method comprising:
configuring, by the eNB, a periodic transmission of the DRS with DRS occasion;
starting, by the eNB, carrier sensing on a channel related to a wireless local area network (WLAN), before the DRS occasion by an amount of time equal to a maximum allowed channel occupancy time of the WLAN;
detecting, by the eNB, when the channel is idle;
occupying, by the eNB, the channel immediately after the channel becomes idle;
transmitting, by the eNB, a reservation signal until the DRS occasion; and
transmitting, by the eNB, the DRS in the DRS occasion,
wherein a periodicity of the DRS occasion is longer than the maximum allowed channel occupancy time.

### Claim 2 (depends on 1)

The method of claim 1, wherein the DRS occasion consists of 3 subframes every 40 ms.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
performing listen-before-talk (LBT) before transmitting the DRS.

### Claim 4 (depends on 3)

The method of claim 3, further comprising:
transmitting the reservation signal after performing the LBT and the channel becomes idle.

### Claim 5

An evolved NodeB (eNB) which operates in LTE in an unlicensed (LTE-U) spectrum, the eNB comprising:
a memory;
a transceiver; and
a processor, operatively coupled to the memory and the transceiver, wherein the processor is configured to:
configure a periodic transmission of a discovery reference signal (DRS) with DRS occasion:
start carrier sensing on a channel related to a wireless local area network (WLAN), before the DRS occasion by an amount of time equal to a maximum allowed channel occupancy time of the WLAN;
detect when the channel is idle;
occupy the channel immediately after the channel becomes idle;
control the transceiver to transmit a reservation signal until the DRS occasion; and
control the transceiver to transmit DRS in the DRS occasion,
wherein a periodicity of the DRS occasion is longer than the maximum allowed channel occupancy time.