KR102321191B1 - Method for performing discontinuous reception in wireless communication system and apparatus using the method - Google Patents

Abstract

A method and apparatus for operating Discontinuous Reception (DRX) in a wireless communication system supporting Licensed Assisted Access (LAA) are provided. In a wireless communication system supporting carrier aggregation between a serving cell of a licensed band and a serving cell of an unlicensed band, the DRX operation method of the terminal includes configuration information on the serving cell of the unlicensed band. ) based on the step of configuring at least one secondary serving cell on the unlicensed band, receiving a channel acquisition indicator for the at least one secondary serving cell from the base station, and the at least one secondary serving cell based on the channel acquisition indicator It may include performing a DRX operation on the serving cell.

Description

Discontinuous reception operation method and apparatus in a wireless communication system

The present invention relates to a method and apparatus for each terminal to apply a discontinuous reception (DRX) operation to an unlicensed band in a wireless communication system.

Cellular is a concept proposed to overcome the limitations of the service area, frequency and subscriber capacity, and divides the mobile communication service area into several small cell units so that frequencies can be spatially reused. . However, in a specific area such as a hotspot inside a cell, a particularly high communication demand occurs, and the reception sensitivity of radio waves may decrease in a specific area such as a cell edge or a coverage hole. Accordingly, for the purpose of enabling communication in a hotspot, a cell boundary, a coverage hole, etc., in a macro cell, small cells, for example, a pico cell, a femto cell, etc. , a micro cell, a remote radio head (RRH), a relay, a repeater, etc. are installed together. Such a network is called a heterogeneous network. In a heterogeneous network environment, a macro cell is a cell having a relatively large coverage, and a small cell such as a femto cell and a pico cell is a cell having a small coverage.

However, with the rapid increase in wireless communication traffic, despite the active use of the small cell as described above, securing more frequencies is still an urgent issue. Accordingly, a method of performing wireless communication using frequencies of not only a licensed band but also an unlicensed band such as a WiFi band based on carrier aggregation (CA) is being discussed. CA is a technology for efficiently using fragmented small bands. In the frequency domain, physically continuous or non-continuous bands are bundled together to achieve the same effect as using a logically large band. it is to do

On the other hand, in general, the power consumption by the receiving circuit of the terminal is a level that cannot be ignored, and the continuous operation of the receiving circuit increases the power consumption of the terminal. Accordingly, the wireless communication system supports discontinuous reception (DRX) in order to reduce power consumption of the terminal. DRX refers to a function that allows the UE to stop monitoring the Packet Data Control CHannel (PDCCH) for a predetermined period (ie, sleep period or inactive time) Repeat the inactivity time. Here, the active time means a time for monitoring the PDCCH, and the inactive time means a time for stopping monitoring of the PDCCH.

However, since the unlicensed band allows competitive access, when the CA is configured between the serving cell of the licensed band and the serving cell of the unlicensed band, the existing DRX operation cannot be applied as it is. For example, when a channel of an unlicensed band is acquired during an inactive time, a problem occurs that the terminal cannot receive a PDCCH from the base station due to a DRX operation despite acquiring a channel of the unlicensed band. In order to prevent this, if the terminal always monitors the PDCCH through the serving cell of the unlicensed band even during the DRX operation, there is a problem in that the terminal's power is consumed excessively. Therefore, it is necessary to define a DRX operation to solve this problem.

An object of the present invention is to provide a method and apparatus for operating DRX for an unlicensed band in a wireless communication system.

Another technical object of the present invention is to provide a method and apparatus for operating DRX for data reception in a wireless communication system in which carrier aggregation is configured using a serving cell of a licensed band and a serving cell of an unlicensed band.

According to an aspect of the present invention, a method of operating Discontinuous Reception (DRX) of a terminal in a wireless communication system supporting carrier aggregation between a serving cell of a licensed band and a serving cell of an unlicensed band is described above. Configuring at least one secondary serving cell on the unlicensed band based on configuration information on the serving cell of the unlicensed band, receiving a channel acquisition indicator for the at least one secondary serving cell from the base station; The method may include performing a DRX operation for the at least one secondary serving cell based on the channel acquisition indicator.

According to another aspect of the present invention, in a wireless communication system supporting carrier aggregation between a serving cell of a licensed band and a serving cell of an unlicensed band, the terminal is based on the configuration information on the serving cell of the unlicensed band at least one on the unlicensed band. Controls the DRX operation for the at least one secondary serving cell based on a configuration unit configuring a secondary serving cell of It may include a control unit that

Even when carrier aggregation is configured between the serving cell of the licensed band and the serving cell of the unlicensed band, the DRX operation for efficiently receiving data transmitted by the base station is possible. Therefore, it has the advantage of correctly supporting the DRX operation for power consumption of the terminal. In addition, as the data is received through the unlicensed band, it has the advantage of reducing the cost for the user to use the service.

1 shows a wireless communication system to which the present invention is applied.
2 shows examples of LAA deployment scenarios to which the present invention is applied.
3 is a diagram illustrating a DRX operation method according to an embodiment of the present invention.
4 is a diagram for explaining DRX.
5 shows an example of timing for contention-based channel acquisition.
6 is a diagram illustrating a DRX operation method according to another embodiment of the present invention.
7 is a diagram illustrating a DRX operation method according to another embodiment of the present invention.
8 is a flowchart illustrating an operation of a terminal according to an embodiment of the present invention.
9 is a flowchart illustrating an operation of a base station according to an embodiment of the present invention.
10 is a block diagram illustrating a wireless communication system according to an embodiment of the present invention.

Hereinafter, some embodiments will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated on different drawings. In addition, in describing the embodiments of the present specification, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present specification, the detailed description thereof will be omitted.

In addition, this specification describes a wireless communication network, and the work performed in the wireless communication network is performed in the process of controlling the network and transmitting data in a system (eg, a base station) having jurisdiction over the wireless communication network, or the corresponding wireless communication network. The operation may be performed in a terminal connected to the network.

1 shows a wireless communication system to which the present invention is applied.

The network structure shown in FIG. 1 may be an Evolved-Universal Mobile Telecommunications System (E-UMTS) network structure. The E-UMTS system may include a Long Term Evolution (LTE), an advanced LTE (LTE-A) system, and the like. Wireless communication systems are widely deployed to provide various communication services such as voice, packet data, and the like.

On the other hand, there is no limitation on the multiple access technique applied to the wireless communication system. Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA (SC-FDMA), OFDM-FDMA, OFDM-TDMA , various multiple access schemes such as OFDM-CDMA can be used.

Referring to FIG. 1 , the E-UTRAN includes at least one base station (BS) 20 that provides a control plane and a user plane to a terminal. The terminal 10 (User Equipment, UE) may be fixed or mobile, and other term can be called.

The base station 20 generally refers to a station communicating with the terminal 10, and an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, and a femto-eNB. ), a pico base station (pico-eNB), a home base station (Home eNB), may be referred to as other terms such as relay (relay). The base station 20 may provide at least one cell to the terminal. A cell may mean a geographic area in which the base station 20 provides a communication service, or may mean a specific frequency band. A cell may mean a downlink frequency resource and an uplink frequency resource. Alternatively, the cell may mean a combination of a downlink frequency resource and an optional uplink frequency resource. In addition, in general, when carrier aggregation (CA) is not considered, uplink and downlink frequency resources are always present as a pair in one cell.

An interface for transmitting user traffic or control traffic may be used between the base stations 20 . The source base station (Source BS, 21) means a base station in which a radio bearer is currently established with the terminal 10, and the target base station (Target BS, 22) is a new terminal after the terminal 10 disconnects the radio bearer with the source base station 21. It means a base station to handover to establish a radio bearer. The base stations 20 may be connected to each other through an X2 interface. The X2 interface is used to send and receive messages between the base stations 20 . In addition, the base station 20 is connected to an Evolved Packet System (EPS), more specifically, a Mobility Management Entity (MME)/Serving Gateway (S-GW) 30 through the S1 interface. The S1 interface supports a many-to-many-relation between the base station 20 and the MME/S-GW 30 . The PDN-GW 40 is used to provide packet data service to the MME/S-GW 30 .

Hereinafter, downlink means communication from the base station 20 to the terminal 10 , and uplink means communication from the terminal 10 to the base station 20 . The downlink is also called a forward link, and the uplink is also called a reverse link. In the downlink, the transmitter may be a part of the base station 20 , and the receiver may be a part of the terminal 10 . In the uplink, the transmitter may be a part of the terminal 10 , and the receiver may be a part of the base station 20 . In a wireless communication system, a Time Division Duplex (TDD) method transmitted using different times may be used as uplink transmission and a downlink transmission method, or a Frequency Division Duplex (FDD) method transmitted using different frequencies may be used. can be used

Meanwhile, carrier aggregation (CA) supports a plurality of carriers and is also referred to as spectrum aggregation or bandwidth aggregation. An individual unit carrier bundled by carrier aggregation is called a component carrier (CC). Each component carrier is defined by its bandwidth and center frequency. For example, if five component carriers are allocated as a granularity of a carrier unit having a bandwidth of 20 MHz, a bandwidth of up to 100 MHz may be supported.

Hereinafter, a multiple carrier system includes a system supporting carrier aggregation (CA). A serving cell may be defined as a component frequency band that may be aggregated by CA based on a multiple component carrier system. The serving cell includes a primary serving cell (PCell) and a secondary serving cell (SCell). The primary serving cell provides a security input and Non-Access Stratum (NAS) mobility information in a Radio Resource Control (RRC) connection (establishment) or re-establishment state. It means a serving cell. According to the capabilities of the terminal, at least one cell may be configured to form a set of serving cells together with a primary serving cell. The at least one cell is referred to as a secondary serving cell. A set of serving cells configured for one UE may be configured with only one primary serving cell, or may include one primary serving cell and at least one secondary serving cell. Each serving cell may be operated in an activated or deactivated state.

2 shows examples of an LAA deployment scenario to which the present invention is applied.

It is difficult to meet the increasing demand for data services by simply dividing cells into macro cells and micro cells. Accordingly, small cells such as a pico cell, a femto cell, and a wireless relay may be used for a data service. In general, since a small cell serves a smaller area compared to a macro cell, it is advantageous compared to a macro cell in terms of throughput that can be provided to a single terminal. However, as wireless communication traffic rapidly increases, securing more frequencies in order to improve throughput is emerging as an urgent problem. Accordingly, a method for performing wireless communication using frequencies of not only a licensed band but also an unlicensed band such as a WiFi band is being discussed. In order to smoothly support wireless communication in the unlicensed band, wireless communication in the unlicensed band may be provided under the support of the communication technique of the licensed band.

Hereinafter referred to as License Assisted Access (LAA), the CA operation for one or more secondary serving cells operating in the unlicensed band or unlicensed spectrum is supported based on the assistance of the primary serving cell operating in the licensed band or spectrum. represents a wireless communication technique. In other words, LAA is a technology that binds the licensed band and the unlicensed band together using the CA using the LTE licensed band as an anchor. In this case, one of the serving cells in the licensed band may be used as the primary serving cell, and the serving cells in the unlicensed band may always be configured as secondary serving cells. In addition, the unlicensed band is activated only through CA and may not perform LTE communication alone. The terminal accesses the network with the licensed band to use the service, and the base station combines the licensed band and the unlicensed band with CA depending on the situation to offload traffic of the licensed band to the unlicensed band.

2 illustrates, as an example, various LAA deployment scenarios. In each scenario, the number of licensed carriers and unlicensed carriers may each be one or more. As an example, scenario 1 is a case in which a macro cell using a licensed carrier F1 (frequency 1) and a small cell using an unlicensed carrier F3 are connected by carrier aggregation (CA). In this case, the macro cell and the small cell may be non-co-located and may be connected to each other through an ideal backhaul.

As another example, scenario 2 is a case where small cell #1 using a licensed carrier F2 and small cell #2 using an unlicensed carrier F3 are connected by carrier aggregation in addition to macro cell coverage. In this case, the small cell #1 and the small cell #2 may be co-located with each other, and thus an ideal backhaul may be assumed for each other.

As another example, scenario 3 is a case in which there are a macro cell and a small cell #1 using a licensed carrier F1, and the small cell #1 and a small cell #2 using an unlicensed carrier F3 are connected by carrier aggregation. In this case, the macro cell and the small cell #1 may be connected to each other through an ideal or non-ideal backhaul, and the small cell #1 and the small cell #2 may be connected (and co-located) to each other by an ideal backhaul. ) can be

As another example, scenario 4 includes a macro cell using a licensed carrier F1, a small cell #1 using a licensed carrier F2, and a small cell #2 using an unlicensed carrier F3, a small cell #1 and a small cell. This is the case where #2 is connected by carrier aggregation. In this case, the macro cell and the small cell #1 may be connected to each other through an ideal or non-ideal backhaul, and the small cell #1 and the small cell #2 may be connected (and co-located) to each other by an ideal backhaul. ) can be If the macro cell and the small cell #1 are connected to each other through an ideal backhaul, the macro cell F1, the small cell #1 (F2), and the small cell #2 (F3) may be connected by carrier aggregation. .

However, since the unlicensed band allows competitive access, when the CA is configured between the serving cell of the licensed band and the serving cell of the unlicensed band, the existing discontinuous reception (DRX) operation cannot be applied as it is. For example, when the channel of the unlicensed band is acquired during the inactive time of the terminal, the terminal cannot receive the PDCCH from the base station due to the DRX operation despite acquiring the channel of the unlicensed band. In order to prevent this, if the terminal always monitors the PDCCH through the serving cell of the unlicensed band even during the DRX operation, there is a problem in that the terminal's power is consumed excessively. Therefore, when the UE performs CA based on LAA, an improved DRX operation method in an unlicensed band is required.

3, 6 and 7 are diagrams illustrating DRX operation embodiments according to the present invention, FIG. 4 is a diagram for explaining specific parameters related to the DRX operation of the present invention, and FIG. 5 is a diagram for contention-based channel acquisition An example of timing is shown.

Hereinafter, in the present specification, a scenario in which one primary serving cell (PCell) and one first secondary serving cell (SCell#1) are configured in a licensed band, and one second secondary serving cell (SCell#2) is configured in an unlicensed band Assuming that is explained. However, this is only an example, and scenarios of the number and combination of the primary serving cell and the secondary serving cell in the licensed band and the unlicensed band may vary, and the technical idea of the present invention can be applied to all possible scenarios. Each of the secondary serving cells (SCell#1 and SCell#2) may be operated in an activation or deactivation state, but in the present invention, the secondary serving cell (SCell#2) of the unlicensed band is in an active state. Assume

One system frame on the time axis may be composed of 10 sub-frames as shown in FIG. 3 . One subframe may consist of two slots.

On the other hand, the wireless communication system supports discontinuous reception (DRX) in order to reduce the power consumption of the terminal. DRX refers to a function that allows the UE to stop monitoring the PDCCH for a predetermined period (sleep period or inactive time). The UE repeats the active time and the inactive time in a constant cycle in the DRX mode as shown in FIG. 4 , which is referred to as a DRX operation. Here, the active time means a time for monitoring a Packet Data Control CHannel (PDCCH), and the inactive time means a time for stopping monitoring of the PDCCH. From the viewpoint of the UE, the UE monitors the PDCCH during the active time and stops monitoring during the inactive time.

Referring back to FIG. 3, when CA is configured based on LAA, the DRX operation in the licensed band is the common DRX operation in which the serving cells (PCell and SCell#1) in the licensed band always have the same active time period. Can be applied. have. In addition, in terms of DRX parameters, DRX parameters on a per-terminal basis may be configured. That is, DRX parameters commonly applied to the licensed band and the unlicensed band may be configured in the terminal. Alternatively, the first DRX parameters applied to the licensed band and the second DRX parameters applied to the serving cells of the unlicensed band may be configured independently. In this case, the first DRX parameters and the second DRX parameters may be the same as or different from each other.

First, the DRX operation in the licensed band will be described in more detail as follows.

For example, the DRX cycle may be set to 16 subframe sections, and the active time and inactive time may be set to 2 subframe sections and 14 subframe sections, respectively. Transmission Power Control (TPC)-PUCCH-, which can identify that the terminal includes C-RNTI (Cell-Radio Network Temporary Identifier), which is a unique identifier of the terminal, or power control information for each uplink channel for the terminal during the active time Monitoring of the scrambled PDCCH may be performed based on the RNTI, the TPC-PUSCH-RNTI, and the SPS-RNTI that may identify that resource allocation information for SPS (Semi Persistent Scheduling) is included. Monitoring of the PDCCH may be controlled by DRX operation, and the DRX-related parameters are transmitted by the base station to the terminal through RRC (Radio Resource Control) signaling. In addition to the RNTIs, a monitoring-related operation for the PDCCH scrambled with identifiers such as SI (System Information)-RNTI, P (Paging)-RNTI, etc. is independent of the DRX operation.

If the DRX parameter is configured in the RRC connected state, the UE may perform discontinuous monitoring of the PDCCH based on the DRX operation. On the other hand, if the DRX parameter is not configured, the UE continuously monitors the PDCCH. Here, discontinuous monitoring means that the UE monitors the PDCCH only in specific subframes (subframes #0 and #1 in FIG. 3), and continuous monitoring means that the UE monitors the PDCCH in all subframes. can

The RRC layer manages several timers to control the DRX operation. The timer for controlling the DRX operation includes a duration timer (onDurationTimer), a DRX inactivity timer (drx-Inactivity Timer), and a DRX retransmission timer (drx-Retransmission Timer). In addition, there are a long DRX cycle (longDRX-Cycle) and a DRX start offset (drxStartOffset) as parameters controlling the DRX operation, and the base station optionally sets the DRX short cycle timer (drxShortCycleTimer) and the short DRX-cycle can In addition, a HARQ Round Trip Time (RTT) timer is defined for each downlink Hybrid Automatic Repeat Request (HARQ) process.

The DRX start offset is a value that defines the subframe in which the DRX cycle starts. The DRX short cycle timer is a timer that defines the number of consecutive subframes in which the UE must follow the short DRX cycle. The HARQ RTT timer is a timer defining the minimum number of subframes before a period in which downlink HARQ retransmission is expected by the terminal.

The duration timer is started when the DRX cycle begins. That is, the start time of the duration timer coincides with the start time of the DRX cycle. The duration timer expires when the duration timer value is equal to the preset expiration value by increasing the value by '1' for every PDCCH subframe. Until the duration timer value becomes equal to the expiration value, the duration timer continues to be valid.

The DRX inactivity timer is a time for monitoring the PDCCH for successful decoding of a PDCCH to be received later from the time when the PDCCH for uplink or downlink user data transmission is successfully decoded. The DRX inactivity timer is started or restarted when the UE successfully decodes the PDCCH for the first HARQ transmission in the PDCCH subframe.

The DRX retransmission timer is a timer that operates based on the maximum value of the consecutive number of PDCCH subframes expected for downlink retransmission by the base station when decoding of HARQ process data previously received by the terminal fails. Since the DRX retransmission timer is basically for retransmission reception for the same HARQ process, the HARQ RTT timer defining a time during which retransmission does not occur for the same HARQ process should expire.

Therefore, even though the HARQ RTT timer has expired, it is started when the decoding of data in the corresponding HARQ process is still unsuccessful. The UE may define an active time while the DRX retransmission timer is in progress, and may monitor the reception of data retransmitted in the corresponding HARQ process as well as other PDCCHs. The setting of the DRX retransmission timer is defined by a related parameter in the MAC-MainConfig message of the RRC layer. The DRX retransmission timer may be operated for each HARQ process.

When the DRX cycle is configured, the UE monitors the PDCCH for the PDCCH subframe during the active time. Here, the PDCCH subframe means a subframe including the PDCCH. The active time may mean all the periods in which the terminal is awake. For example, the terminal becomes the active time when at least one of the above-described duration timer, DRX inactivity timer, and DRX retransmission timer is in progress. In addition, it becomes the active time even when a scheduling request is sent or pending through the PUCCH, and it becomes the active time even when an uplink grant for pending HARQ transmission occurs and data exists in the corresponding HARQ buffer. In addition, it is an active time even when the PDCCH indicating new transmission to the C-RNTI of the UE is not received after the random access response to the preamble that is not selected by the UE is successfully received. A time other than the active time during the DRX cycle may be referred to as an inactive time. The active time may be referred to as a wake up period, and the inactive time may be referred to as a sleep period.

In addition, when DRX is configured, the terminal stops the duration timer and the DRX inactivity timer when a DRX command MAC control element is received in each subframe. In addition, when the DRX inactivity timer expires or a DRX command MAC control element is received, a short DRX cycle is used and the DRX short cycle timer is started or restarted, or a long DRX cycle is used. The UE uses a long DRX cycle when the DRX short cycle timer expires. If a short DRX cycle or a long DRX cycle is used, the UE starts a duration timer.

On the other hand, the unlicensed band permits a process in which a base station or a terminal acquires a channel access opportunity based on contention. There may be several contention-based channel access methods, and a channel access mechanism for an unlicensed band according to the present invention includes the following.

The channel access mechanism according to the present invention provides opportunistic channel access. To this end, a wireless communication device such as a base station performs Clear Channel Assessment (CCA) or Extended Clear Channel Assessment (ECCA) before using a corresponding channel. This is to avoid transmission that occurs concurrently on the same channel with other RLAN (Radio Local Area Network) systems. Here, the CCA or ECCA determines whether the corresponding channel is in the channel interference, occupied or unoccupied state, that is, whether the corresponding channel is in a busy state or an idle state, through energy scan or detection of the corresponding channel. is a procedure to Such a channel access mechanism may be referred to as Listen Before Talk (LBT) or Carrier Sense (CS).

Under the LBT protocol, the wireless communication device determines whether a corresponding channel is available for transmission based on energy measured in the corresponding channel. LBT may be performed on a frame-based or load-based basis. 5, as an example, timing for frame-based LBT is shown. Referring to Figure 5, parameters such as CCA, extended CCA, channel occupancy time, idle period, CCA energy detection threshold to satisfy the LBT requirements can be defined. A wireless communication device using an unlicensed band may perform (E) CCA check at the end of an idle period before starting transmission in an operating channel.

That is, the wireless communication device can determine the occupancy state of the channel by performing (E)CCA check as much as (E)CCA execution time within the idle period. When the wireless communication device correctly receives the packet intended for the device on the channel occupied by performing CCA before, if it does not exceed the maximum channel occupancy time, it does not perform (E)CCA again and manages and control frames (eg, ACK and Block ACK frames) may be transmitted.

Such a competitive channel acquisition mechanism in the unlicensed band may affect the DRX operation in the unlicensed band. Because the mobile communication system operating within the licensed band does not have a competitive channel acquisition operation, there is no need to notify the terminal that the base station has acquired the corresponding channel. However, in the unlicensed band, if there is no signaling for the base station to notify whether the channel has been acquired, the terminal cannot know whether the base station has acquired the downlink channel, so power consumption due to unnecessary data reception operation may occur.

Therefore, in order to prevent such unnecessary power consumption according to the present invention, the DRX operation in the unlicensed band is to provide various embodiments according to a method of notifying the terminal of the fact that the base station has acquired the channel. In addition, the base station may explicitly or implicitly inform the terminal that the channel has been acquired. For example, information indicating that a channel has been acquired by the base station is referred to as a channel acquisition indicator.

As an embodiment, the base station may indicate that the channel has been acquired in the unlicensed band by transmitting a preamble or a reference signal (RS) to the terminal as a channel acquisition indicator. That is, the base station may inform the terminal of the acquisition of the channel implicitly through the preamble or the reference signal. In this case, when the terminal receives the preamble or the reference signal, it may recognize it as a channel acquisition indicator. In more detail, when the UE receives the preamble or the reference signal during the DRX inactivity time, it may be recognized as a channel acquisition indicator.

On the other hand, with respect to the transmission/reception time aspect of the channel acquisition indicator, the channel acquisition indicator is a corresponding sub including the end time from the end time of the (E)CCA period due to channel acquisition through evaluation within the (E)CCA period of the base station. It may be transmitted by the base station or received by the terminal within the frame end time interval. The time period occupied by the channel acquisition indicator among the time period may be the entire period in order to prevent occupancy by equipment in other wireless communication systems using the same unlicensed band, or a frame structure operating in a licensed band. , or an OFDM symbol interval may be part of the consideration. In addition, the frequency band occupied by the channel acquisition indicator in the available frequency band in the serving cell may be the entire frequency band for the same reason as above, and the frame structure operating in the licensed band for the whole, or an OFDM symbol period, etc. could be

In one aspect, as shown in FIG. 3, the base station acquires a channel by performing (E) CCA in the first slot of sub-frame #1 in system frame #1. In this case, the base station may transmit a channel acquisition indicator (preamble or RS, etc.) through the secondary serving cell (SCell #2) of the unlicensed band in the second slot of the sub-frame #1. When the terminal receives the preamble, RS, etc. promised as the channel acquisition indicator through the secondary serving cell (SCell #2) of the unlicensed band, it can recognize that the base station has acquired the corresponding channel. In this case, information data is not transmitted to the corresponding terminal in the period from the end time of the (E)CCA period to the end time of the corresponding subframe (sub-frame #1). Accordingly, the serving cells (sub-serving cells) of all activated unlicensed bands before the UE recognizes the channel acquisition time of the base station may maintain an inactivity time in all subframes after activation. That is, the UE may not perform the monitoring operation for the (E)PDCCH that is always scrambled with the RNTI related to the DRX operation until it recognizes the end time of the (E)CCA period. However, the terminal performs monitoring for the channel acquisition indicator (preamble or RS, etc.) during the inactivity time. Here, the (E)PDCCH is a channel for transmitting control information to which a beamforming technique is applied similarly to PDSCH transmission based on DMRS. This is also used as a channel for transmitting control information based on the MIMO technique. The PDCCH is to be monitored based on Cell-Radio Network Temporary Identifier (C-RNTI), Transmission Power Control (TPC)-PUCCH-RNTI, TPC-PUSCH-RNTI, and Semi Persistent Scheduling (SPS)-RNTI, which are unique identifiers of the UE. can Extended PDCCH (EPDCCH) may be monitored based on the number of resource elements available as EPDCCH, downlink control information (DCI) format, and a coding rate for common DCI.

In the case of a base station performing ECCA through frame-based LBT, the monitoring period is set to monitor a part of the channel occupancy time based on a fixed frame period parameter determined internally by the base station as shown in FIG. 5 One channel acquisition indicator monitoring parameters may be indicated to the UE through the licensed band using RRC signaling. The channel acquisition indicator monitoring parameters may be configured in the terminal separately from DRX. In the present invention, as an example, it is assumed that the DRX operation and the channel acquisition indicator monitoring operation cannot be simultaneously operated.

In another aspect, the DRX-related timers for the secondary serving cell (SCell #2) of the unlicensed band operated in the LAA form may be operated independently from the DRX-related timers for the serving cells (PCell and SCell #1) of the licensed band. have.

As an example, the UE may change the value of the on duration timer for the secondary serving cell (SCell #2) of the unlicensed band based on the channel acquisition interval information. Here, the channel acquisition interval information may be transmitted from the base station to the terminal by being included in the preamble, may be transmitted independently, or may be transmitted while being included in a signal other than the preamble.

As another example, the UE may perform the DRX operation based on information on the time to apply the DRX operation to the secondary serving cell (SCell #2) of the unlicensed band, that is, information on the back-off time. have. Here, the information on the back-off time may be transmitted from the base station to the terminal by being included in the preamble, may be transmitted independently, or may be transmitted by being included in a signal other than the preamble.

As an example, the terminal receives a preamble including information indicating two subframe sections as the back-off time in subframe #1 of the system frame #1 through the secondary serving cell (SCell #2) of the license band. In this case, as shown in FIG. 3 , the DRX parameter may be applied from subframe #4 of the system frame #1 to the secondary serving cell (SCell #2) of the license band. Accordingly, the terminal may receive data from subframe #4 of the system frame #1 through the secondary serving cell (SCell #2) of the license band. Alternatively, the information on the back-off time may be provided by the base station through RRC signaling as one of the channel acquisition indicator monitoring parameters.

As another example, the terminal changes the drxStartOffset value for serving cells in the unlicensed band to start a duration timer to transition to the active time based on the channel acquisition time, or change the short cycle and/or long cycle value. may be The drxStartOffset and short/long cycle values determine the condition for starting the duration timer as shown in the following equation.

For short cycle: [(SFN * 10) + subframe number] modulo (shortDRX-Cycle) = (drxStartOffset) modulo (shortDRX-Cycle)

For long cycle: [(SFN * 10) + subframe number] modulo (longDRX-Cycle) = drxStartOffset

Here, SFN is a system frame number. DRX parameters for the secondary serving cell of the unlicensed band are applied from the subframe (sub-frame #1 in FIG. 3) including the time when the contention-based channel acquisition period ends, or after the back-off time (sub-frame in FIG. 3) It can be applied to frame #4).

As another example, reception of the channel acquisition indicator may be added to the condition that the terminal starts the DRX inactivity timer to transition to the active time based on the channel acquisition time. DRX parameters for the secondary serving cell of the unlicensed band are applied from the subframe (sub-frame #1 in FIG. 3) including the time when the contention-based channel acquisition period ends, or after the back-off time (sub-frame in FIG. 3) #4) can be applied.

Meanwhile, as another embodiment, the base station may explicitly indicate that the channel has been acquired in the unlicensed band by transmitting the EPDCCH including the channel acquisition indicator to the terminal through the secondary serving cell of the unlicensed band. In this case, the DRX operation may be performed, for example, as shown in FIG. 6 .

6 is a diagram illustrating a DRX operation method according to another embodiment of the present invention.

6 illustrates a DRX operation method when the base station acquires a channel by performing (E) CCA check in the first slot of sub-frame #1 in system frame #1 as another embodiment. . In this case, the base station sends a physical layer control message including a channel acquisition indicator through the secondary serving cell (SCell #2) of the unlicensed band from the first OFDM symbol of the second slot of the sub-frame #1. can be transmitted Upon receiving the physical layer control message through the secondary serving cell (SCell #2) of the unlicensed band, the terminal may recognize that the corresponding channel in the unlicensed band has been obtained. Here, the physical layer control message may be an extended PDCCH (EPDCCH). In order to receive the EPDCCH, the UE may maintain an active time in all subframes after activating serving cells of all activated unlicensed bands before recognizing the end time of the (E)CCA period. That is, the monitoring operation for the EPDCCH scrambled with the RNTI to be monitored through the DRX operation may be performed. In this case, information data may be transmitted to the corresponding terminal from the end of the (E)CCA period or from the second slot of the corresponding subframe (sub-frame #1).

Even in this case, the DRX-related timers for the secondary serving cell (SCell #2) of the unlicensed band operated in the LAA form may be operated independently from the DRX-related timers for the serving cells (PCell and SCell #1) of the licensed band. . For example, the physical layer control message may include channel acquisition period information for the unlicensed band. In this case, the terminal may change the value of the on duration timer for the secondary serving cell (SCell #2) of the unlicensed band based on the channel acquisition period information included in the physical layer control message. In addition, the value of the DRX start offset short cycle and/or long cycle may be changed based on the channel acquisition interval information.

As another embodiment, the base station may explicitly indicate that the channel has been acquired in the unlicensed band by transmitting the PDCCH or EPDCCH including the channel acquisition indicator to the terminal through the serving cell of the licensed band. In this case, the DRX operation may be performed, for example, as shown in FIG. 7 .

7 is a diagram illustrating a DRX operation method according to another embodiment of the present invention.

7 illustrates a DRX operation method when the base station performs (E)CCA check in the first slot of sub-frame #5 in system frame #2 as another embodiment. In this case, the base station (E) the primary serving cell (PCell) or secondary serving cell of the licensed band in the next subframe (sub-frame #6) of the subframe (sub-frame #5) including the end time of the CCA period A physical layer control message including a channel acquisition indicator may be transmitted through (SCell #1).

7 illustrates a case in which the PDCCH is transmitted through the primary serving cell as a physical layer control message as an example. The physical layer control message may include a PDCCH and an EPDCCH. When the terminal receives the physical layer control message including the channel acquisition indicator through the primary serving cell (PCell) or the secondary serving cell (SCell #1) of the licensed band, it can recognize that the corresponding channel in the unlicensed band has been acquired. Accordingly, the terminal can maintain the inactivity time in all subframes after activation for all activated serving cells (sub-serving cells) of the unlicensed band before recognizing the channel acquisition time in the unlicensed band of the base station. That is, the monitoring operation for the (E)PDCCH scrambled with the RNTI related to the DRX operation may not be performed until the end time of the (E)CCA period is recognized. In other words, if a physical layer control message including a channel acquisition indicator for an unlicensed band is not received through the serving cell of the licensed band, the terminal may maintain an inactive time for the unlicensed band even if it is an active time for the licensed band. Accordingly, the active time for serving cells in the licensed band defined by the DRX operation and the active time for serving cells in the unlicensed band may be different from each other.

However, during the channel acquisition period from after the UE recognizes the acquisition of the channel in the unlicensed band, DRX-related timers for the secondary serving cell (SCell #2) of the unlicensed band operated in the LAA form and the serving cells of the licensed band (PCell and The active time for SCell #1) may be commonly applied.

In this case, since the terminal can recognize that the base station has acquired the corresponding channel in the unlicensed band only after checking the (E)PDCCH received through subframe #6, it can decode the (E)PDCCH and check the information Time cannot be completed before subframe #6. Therefore, from the (E) CCA period end time (channel acquisition time) to the end time period of the sub-frame (sub-frame #6), the monitoring operation for the (E) PDCCH transmitted by the base station through the corresponding channel in the unlicensed band is performed. can't be done On the other hand, when the terminal fails to transmit data through the serving cell in the unlicensed band, the DRX retransmission timer corresponding to the corresponding HARQ process may be started for retransmission reception to transition to the active time. However, according to an embodiment of the present invention, if the channel acquisition in the unlicensed band fails, it cannot receive a signal transmitted from the base station through the corresponding channel, so it has a continuous inactivity time regardless of the active time in the licensed band. In this case, timers related to the DRX operation do not operate based on the serving cells in the unlicensed band.

However, the UE is operating the resources of the serving cell in the unlicensed band through cross-carrier scheduling, and the first or retransmission is received, but decoding of data included in the PDSCH fails and the HARQ RTT timer expires at the time when the channel in the unlicensed band is received. When the acquisition fails and the base station cannot retransmit through the corresponding serving cell, the retransmission data for the HARQ process in the corresponding serving cell may be transmitted through another serving cell through operation of the serving cell in the physical layer. Here, the cross-carrier scheduling means that the base station transmits PDCCH1 through DL SCC, and PDSCH1 indicated by PDCCH1 is SDL (Supplement DownLink: a configuration in which only DL subframes exist in TDD) through the UE through an unlicensed carrier (UC). In the case of being transmitted as , an operation in which the PDCCH and the PDSCH are transmitted on different serving cells is referred to as cross-carrier scheduling. For the cross-carrier scheduling, information on a serving cell in which the PDSCH1 corresponding to the PDCCH1 exists is included in the PDCCH1, and the base station receives the cross-carrier scheduling through the RRC reconfiguration procedure to configure the cross-carrier scheduling. It is configured in the terminal including the serving cell information for cross-carrier scheduling. Here, the base station first checks whether the occupancy is possible through the CCA or DCS before using the SDL, and assumes that the SDL UC is occupied.

Additionally, in the present invention, a cross-carrier HARQ operation will be described.

Cross-carrier HARQ operation is when the base station transmits PDCCH1 through DL SCC and transmits PDSCH1 indicated by PDCCH1 to the UE through UC of SDL, the UE attempts to decode after receiving PDSCH1, and if decoding fails It includes a method of transmitting the HARQ NACK to the base station through the UL PCC. At this time, the base station needs to perform data retransmission as the HARQ NACK is received. For data retransmission, the base station must check whether the UC of the SDL can be continuously used (ie, can be occupied).

If it is confirmed that the occupancy of the SDL UC is sustainable, the base station continues to use the UC of the SDL (ie, its own serving cell in which data transmission currently occurs) and performs retransmission of the PDSCH (ie, transmission of PDSCH2), but with this, PDSCH2 PDCCH2 including a flag indicating that the serving cell in which is transmitted is UC of SDL is transmitted to the terminal. Alternatively, when the UE can confirm that the SDL in the UC is occupied through an occupancy indicator transmitted from the base station, etc., it can be recognized that the serving cell in which the PDSCH2 is transmitted is the UC of the SDL without additional signaling. In this case, the UE recognizes that the retransmission of the PDSCH by HARQ NACK is performed in the UC of the SDL, and receives the PDSCH2 in the UC of the SDL.

However, if it is confirmed that the occupancy of the SDL UC is impossible, that is, when the terminal does not recognize the occupancy of the SDL UC of the base station because it fails to receive an occupancy indicator transmitted from the base station, the base station sets the secondary serving cell (DL) as the scheduling serving cell. SCC) to perform retransmission of the PDSCH (ie, transmission of PDSCH2), but along with this, PDCCH2 including a flag indicating that the serving cell through which PDSCH2 is transmitted is a DL SCC is transmitted to the UE through the DL SCC. Alternatively, if the terminal cannot confirm that the SDL in the UC is occupied because it has not received the occupancy indicator transmitted from the base station, the terminal transmits the retransmission serving cell information during non-occupancy included in the SDL UC configuration information from the predetermined rule or the base station. It can be recognized that retransmission of the PDSCH (ie, transmission of PDSCH2) will be performed through a secondary serving cell (DL SCC) configured as a scheduling serving cell through the DL SCC. In this case, the UE recognizes that the retransmission of the PDSCH by the HARQ NACK is performed in the DL SCC, and receives the PDSCH2 in the DL SCC.

The 1-bit flag mentioned in the present invention indicates a serving cell indication for PDSCH retransmission. For example, when set to 0, it indicates a DL SCell (UC), and when set to 1, a scheduling serving cell. It can be applied as indicating #0 (scheduling serving cell configured by RRC for cross-carrier scheduling).

In addition, when the cross-carrier HARQ is applied, the state of the serving cells in the licensed band must be transitioned to the active time so that retransmission data of data that has been transmitted through the serving cell in the unlicensed band can be received through the serving cell in the licensed band. do. Therefore, the terminal should maintain the operation of the HARQ RTT timer and the DRX retransmission timer even if it is determined that the channel including the serving cell in the unlicensed band is not acquired by the base station. However, the active time due to the operation of the timers is not applied to serving cells within the unlicensed band.

8 is a flowchart illustrating an operation of a terminal according to an embodiment of the present invention.

Referring to FIG. 8 , in a wireless communication system supporting carrier aggregation (CA) between a serving cell of a licensed band and a serving cell of an unlicensed band, the UE may perform the following DRX operation.

The terminal may configure at least one secondary serving cell on the unlicensed band based on configuration information (hereinafter, referred to as LAA configuration information) on the serving cell of the unlicensed band (S810). For example, the LAA configuration information may be transmitted from the base station to the terminal through the primary serving cell of the licensed band, and may be transmitted through an RRC message. Here, the RRC message may be an RRC connection reconfiguration message. The SCell configuration information of the unlicensed band may include a frequency band to which an unlicensed carrier is allocated, center carrier information, and the like. Since this is derived through the EARFCN value, the EARFCN value may be included in the secondary serving cell configuration information to indicate which frequency band and which center carrier the corresponding secondary serving cell corresponds to.

Thereafter, when the terminal receives a channel acquisition indicator for at least one secondary serving cell configured on the unlicensed band from the base station (S820), it may recognize that the (E)CCA period for the downlink has ended.

Then, based on the channel acquisition indicator, the DRX operation for at least one secondary serving cell configured on the unlicensed band may be performed (S830).

Here, as an embodiment, the channel acquisition indicator may include a preamble or a reference signal transmitted through at least one secondary serving cell on the unlicensed band from the end time of the contention-based channel acquisition period. The preamble or the reference signal may be transmitted to the terminal within a subframe including the end time of the contention-based channel acquisition period. In this case, the information data is not transmitted to the terminal until the end period of the subframe including the end time of the (E) CCA period.

Accordingly, the terminal may maintain the inactivity time until receiving the channel acquisition indicator for the serving cells of the unlicensed band. That is, the UE may not perform monitoring of the (E)PDCCH through the serving cells of the unlicensed band. However, monitoring for the channel acquisition indicator may be performed. The preamble may include information on when to apply a DRX operation to at least one secondary serving cell configured on an unlicensed band, information on a channel acquisition period, and the like. The terminal may change the value of the duration timer for the at least one secondary serving cell or change the value of the short cycle timer or the long cycle timer based on the information on the channel acquisition period. Accordingly, the DRX timer for the serving cell of the unlicensed band may be operated independently from the DRX timer for the serving cell of the licensed band.

Meanwhile, as another embodiment, the channel acquisition indicator may be included in a physical layer control message transmitted through at least one secondary serving cell configured in the unlicensed band in the next slot of the slot including the end time of the contention-based channel acquisition period. . The physical layer control message may be an EPDDCH. Upon receiving the physical layer control message, the UE may recognize that the (E)CCA period has ended and the corresponding channel has been acquired. In this case, the UE may perform a monitoring operation on the EPDCCH transmitted through the activated unlicensed band until recognizing the end time of the (E)CCA section. Accordingly, information data may be transmitted to the terminal from the end time of the (E)CCA period or from the second slot of the subframe including the end time of the (E)CCA period. Even in this case, the DRX-related timers for the serving cells of the unlicensed band operated in the LAA form may be operated independently from the DRX-related timers for the serving cells of the licensed band. To this end, the physical layer control message may include information on the channel acquisition period for the unlicensed band, information on the time to apply the DRX operation, and the like. In this case, the terminal may change the values of the duration timer, the short cycle timer, and/or the long cycle timer for the serving cell of the unlicensed band based on the channel acquisition section information included in the physical layer control message.

Meanwhile, as another embodiment, the channel acquisition indicator is a physical layer transmitted through a serving cell (eg, a primary serving cell) of a licensed band in a subframe next to a subframe including the end time of the contention-based channel acquisition period. It may also be included in the control message. The physical layer control message may be a PDCCH or an EPDCCH. In this case, since the physical layer control message is received through the serving cell of the licensed band, the serving cells of the unlicensed band can maintain an inactivity time after activation. That is, the (E)PDCCH monitoring operation may not be performed for serving cells of the unlicensed band. However, the DRX timer for serving cells configured in the unlicensed band and the DRX timer for serving cells configured in the licensed band may be operated in common.

9 is a flowchart illustrating an operation of a base station according to an embodiment of the present invention.

Referring to FIG. 9 , in a wireless communication system supporting carrier aggregation (CA) between a serving cell of a licensed band and a serving cell of an unlicensed band, the base station may perform the following operation for the DRX operation of the terminal.

The base station may transmit configuration information (LAA configuration information) on the serving cell of the unlicensed band to the terminal through the main serving cell of the licensed band. The LAA configuration information may be transmitted through an RRC message. Here, the RRC message may be an RRC connection reconfiguration message. The LAA configuration information may be information on a new secondary serving cell (a secondary serving cell of an unlicensed band), and the information on the new secondary serving cell is configured when the base station adds a serving cell of an unlicensed band to a serving cell set. can

In addition, the base station may transmit the DRX parameter to the terminal through the RRC message (S910). The DRX parameter may be a parameter commonly applied without distinguishing between serving cells of a licensed band and serving cells of an unlicensed band. Alternatively, the RRC message may include other DRX parameters applied to serving cells of the unlicensed band. The DRX parameter may include a duration timer (onDurationTimer), a DRX inactivity timer (drxInactivity Timer), a DRX retransmission timer (drxRetransmission Timer), a long DRX cycle (longDRX-Cycle), a DRX start offset (drxStartOffset), and the like.

Thereafter, the base station performs a CCA check during the (E)CCA period, and when acquiring a channel of the unlicensed band, the serving cell of the unlicensed band operated in the LAA form within the end time of the subframe including the end time of the (E)CCA period. A physical layer control including a channel acquisition indicator for a secondary serving cell configured in the unlicensed band from the first OFDM symbol of the slot immediately following the slot including the (E) CCA period ending time, or by transmitting a preamble or a reference signal through By transmitting a message or by transmitting a physical layer control message including a physical layer including a channel acquisition indicator for a secondary serving cell configured in an unlicensed band through the next subframe of the subframe including the end time of the E) CCA period, to the terminal (E) It can be informed that the CCA section has ended and that the channel of the unlicensed band has been acquired (S920).

10 is a block diagram illustrating a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 10 , a wireless communication system supporting LAA according to the present invention includes at least one terminal 1000 and at least one base station 1100 .

Each terminal 1000 includes an RF unit (radio frequency (RF) unit, 1010), a processor (processor, 1120), and a memory (memory, 1030). The memory 1030 is connected to the processor 1020 and stores various information for driving the processor 1020 . The RF unit 1010 is connected to the processor 1020 to transmit and/or receive a radio signal. For example, the RF unit 1010 may receive the LAA configuration information, DRX parameters, channel acquisition indicator, etc. posted herein from the base station 1100 .

The memory 1030 may store LAA configuration information, a DRX parameter, a channel acquisition indicator, and the like according to the present specification, and may provide the information to the processor 1020 according to a request of the processor 1020 .

The processor 1020 implements the functions, processes and/or methods proposed herein. Specifically, the processor 1020 causes all steps according to FIGS. 3, 6 and 7 to be performed. For example, the processor 1020 may include a configuration unit 1021 , a recognition unit 1022 , a control unit 1023 , and a DRX processing unit (not shown).

The configuration unit 1021 configures at least one secondary serving cell on the unlicensed band based on configuration information (LAA configuration information) on the serving cell of the unlicensed band.

When the channel acquisition indicator for at least one secondary serving cell configured based on the LAA configuration information is received from the base station, the recognition unit 1022 recognizes that the (E) CCA period has ended and the channel of the unlicensed band has been acquired based on this. .

The controller 1023 controls the DRX operation for at least one secondary serving cell configured in the unlicensed band based on the channel acquisition indicator.

The DRX processing unit checks the DRX parameters included by the RRC and performs a DRX operation. The DRX processing unit may control the DRX operation by independently managing and operating the DRX parameter of the licensed band serving cell and the DRX parameter of the differentiated unlicensed band serving cell. The DRX processing unit may determine whether to apply a common DRX parameter or a differentiated DRX parameter according to the secondary serving cell confirmed by the configuration unit 1021 . This includes selectively applying the DRX parameter according to the configured secondary serving cell information. In other words, the DRX processing unit applies different duration timers, DRX inactivity timers, DRX retransmission timers, long-term DRX cycles, DRX start offsets, etc. to the serving cell of the licensed band and the serving cell of the unlicensed band, or the serving cell of the licensed band. The same duration timer, DRX inactivity timer, DRX retransmission timer, long DRX cycle, DRX start offset, etc. may be applied to the serving cell of the and unlicensed band.

As an embodiment, the channel acquisition indicator may be transmitted from the base station 1100 through at least one secondary serving cell on the unlicensed band within a subframe including the end time of the contention-based channel acquisition period. The channel acquisition indicator may include a preamble or a reference signal. In this case, information data is not transmitted to the terminal 1000 until the end period of the subframe including the end time of the (E) CCA period. Accordingly, the controller 1023 may control the DRX processing unit to maintain an inactivity time before receiving the channel acquisition indicator for the serving cells of the unlicensed band. That is, the controller 1023 may control the terminal 1000 not to perform monitoring of the (E)PDCCH through the serving cells of the unlicensed band. However, monitoring for the channel acquisition indicator may be performed. On the other hand, the preamble may include information on a time point when the DRX operation is applied to at least one secondary serving cell configured on the unlicensed band, information on a channel acquisition period, and the like. The control unit 1023 changes the value of the duration timer for the at least one secondary serving cell based on the information on the channel acquisition period, or by changing the value of the short-term cycle timer or the long-term cycle timer of the terminal 1000. DRX operation can be controlled. That is, the DRX timer for the serving cell of the unlicensed band may be operated independently from the DRX timer for the serving cell of the licensed band.

As another embodiment, the channel acquisition indicator is a physical layer control message transmitted from the base station 1100 through at least one secondary serving cell configured in the unlicensed band in the next slot of the slot including the end time of the contention-based channel acquisition section. may be included. The physical layer control message may be an EPDDCH. When the physical layer control message is received from the RF unit 1010, the recognition unit 1022 may recognize that the (E)CCA period has ended and the corresponding channel has been acquired. In this case, the controller 1023 may perform a monitoring operation on the EPDCCH transmitted through the activated unlicensed band until recognizing the end time of the (E)CCA section. Accordingly, information data may be transmitted to the terminal from the end time of the (E)CCA period or from the second slot of the subframe including the end time of the (E)CCA period. Even in this case, the DRX-related timers for the serving cells of the unlicensed band operated in the LAA form may be operated independently from the DRX-related timers for the serving cells of the licensed band. To this end, the physical layer control message may include information on the channel acquisition period for the unlicensed band, information on the time to apply the DRX operation, and the like. In this case, the controller 1023 may change the values of the duration timer, the short cycle timer, and/or the long cycle timer for the serving cell of the unlicensed band based on the channel acquisition section information included in the physical layer control message.

As another embodiment, the channel acquisition indicator is a physical layer control message transmitted through a serving cell (eg, a primary serving cell) of a licensed band in a subframe next to a subframe including the end time of the contention-based channel acquisition period. may be included in The physical layer control message may be a PDCCH or an EPDCCH. In this case, since the physical layer control message is received through the serving cell of the licensed band, the serving cells of the unlicensed band can maintain an inactivity time after activation. That is, the (E)PDCCH monitoring operation may not be performed for serving cells of the unlicensed band. However, the DRX timer for serving cells configured in the unlicensed band and the DRX timer for serving cells configured in the licensed band may be operated in common.

Meanwhile, the base station 1100 includes a radio frequency (RF) unit 1110 , a processor 1120 , and a memory 1130 . The memory 1130 is connected to the processor 1120 and stores various information for driving the processor 1120 . The RF unit 1110 is connected to the processor 1120 to transmit and/or receive a radio signal. The processor 1120 implements the functions, processes and/or methods proposed herein. In the above-described embodiment, the operation of the base station 1100 may be implemented by the processor 1120 . The processor 1120 generates the LAA configuration information and the DRX parameters posted herein, and performs a CCA check for the unlicensed band to obtain a channel.

To this end, the processor 1120 includes an LAA configuration information generator 1121 , a DRX parameter generator 1122 , and a channel acquirer 1123 . LAA configuration information and DRX parameters generated by the LAA configuration information generating unit 1121 and the DRX parameter generating unit 1122 may be transmitted to the terminal 1110 through the RF unit 1110 in the form of an RRC message. The RRC message may be an RRC connection reconfiguration message.

The DRX parameter generator 1122 may generate a DRX parameter for independently managing and operating the DRX parameter of the licensed band serving cell and the differentiated DRX parameter of the unlicensed band serving cell. The DRX parameter generator 1122 sets different duration timers, DRX inactivity timers, DRX retransmission timers, long-term DRX cycles, DRX start offsets, etc., for a serving cell of a licensed band and a serving cell of an unlicensed band, respectively, or a licensed band The same duration timer, DRX inactivity timer, DRX retransmission timer, long DRX cycle, DRX start offset, etc. may be set for the serving cell of and the serving cell of the unlicensed band.

The channel acquisition unit 1123 performs a CCA check during the (E) CCA period to acquire a channel of an unlicensed band. When the channel of the unlicensed band is acquired, the RF unit 1110 transmits a preamble or a reference signal through the serving cell of the unlicensed band operated in the LAA form within the end time of the subframe including the (E) CCA period end time. or (E) transmits a physical layer control message including a channel acquisition indicator for a secondary serving cell configured in an unlicensed band from the first OFDM symbol of the slot immediately following the slot including the end time of the CCA section, or (E) CCA The physical layer control message including the physical layer including the channel acquisition indicator for the secondary serving cell configured in the unlicensed band may be transmitted through the next subframe of the subframe including the period end time. Upon receiving the above-described channel acquisition indicator, the terminal 1000 may recognize that the (E) CCA period has ended and that the channel of the unlicensed band has been acquired.

The above-described processor may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and/or a data processing device. Memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and/or other storage devices. The RF unit may include a baseband circuit for processing a radio signal. When the present embodiment is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) that performs the above-described function. A module may be stored in a memory and executed by a processor. The memory may be internal or external to the processor, and may be coupled to the processor by various well-known means.

Claims (15)

A method of performing a discontinuous reception (DRX) operation of a terminal in a wireless communication system, the method comprising:
Receiving a Radio Resource Control (RRC) message including configuration information on carrier aggregation between a serving cell of a licensed band and a serving cell of an unlicensed band from a base station;
configuring at least one secondary serving cell on the unlicensed band based on configuration information on the serving cell of the unlicensed band;
receiving a channel acquisition indicator for the at least one secondary serving cell from a base station; and
Comprising the step of performing a discontinuous reception (DRX) operation for the at least one secondary serving cell based on the channel acquisition indicator,
The channel acquisition indicator indicates that the unlicensed band channel is acquired based on a preamble or a reference signal transmitted through the at least one secondary serving cell.
delete According to claim 1,
The DRX operation method, characterized in that the preamble or the reference signal is transmitted to the terminal within a subframe including the end time of the contention-based channel acquisition period. According to claim 1,
The DRX operation method, characterized in that the preamble includes information on when to apply the DRX operation to the at least one secondary serving cell. According to claim 1,
The step of performing the discontinuous reception (DRX) operation comprises:
and changing a value of a DRX parameter for the at least one secondary serving cell based on the channel acquisition indicator. 6. The method of claim 5,
The DRX parameter is
A DRX operating method comprising at least one of an on duration timer, a short cycle timer, and a long cycle timer. According to claim 1,
The DRX timer for the at least one secondary serving cell,
DRX operation method, characterized in that it operates independently of the DRX timer for the serving cell of the licensed band. According to claim 1,
The channel acquisition indicator,
The DRX operation method, characterized in that it is included in a physical layer control message transmitted through the at least one secondary serving cell in a slot next to a slot including the end time of the contention-based channel acquisition period. According to claim 1,
The channel acquisition indicator,
DRX operation method, characterized in that it is included in the physical layer control message transmitted through the serving cell of the licensed band in the subframe next to the subframe including the end time of the contention-based channel acquisition period. 10. The method of claim 9,
DRX operation method, characterized in that the DRX timer for the at least one secondary serving cell and the DRX timer for the serving cell of the licensed band are operated in common. In the terminal for performing a discontinuous reception (DRX, Discontinuous Reception) operation in a wireless communication system,
Check the configuration information for carrier aggregation between the serving cell of the licensed band and the serving cell of the unlicensed band, and based on the configuration information on the serving cell of the unlicensed band, the a configuration unit for configuring at least one secondary serving cell on an unlicensed band;
a radio frequency (RF) unit for receiving a channel acquisition indicator for the at least one secondary serving cell from a base station; and
A controller for controlling a discontinuous reception (DRX) operation for the at least one secondary serving cell based on the channel acquisition indicator,
The channel acquisition indicator indicates that the unlicensed band channel is acquired based on a preamble or a reference signal transmitted through the at least one secondary serving cell.
delete 12. The method of claim 11,
The control unit is
A terminal characterized in that the value of the DRX parameter for the at least one secondary serving cell is changed based on the channel acquisition indicator. 12. The method of claim 11,
The control unit is
A terminal characterized in that the value of at least one DRX parameter of an on duration timer, a short cycle timer, and a long cycle timer is changed. 12. The method of claim 11,
The control unit is
The terminal, characterized in that it controls the DRX timer for the at least one secondary serving cell to be operated independently from the DRX timer for the serving cell of the licensed band.

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