KR20160092680A - Method and apparatus of performing communication on unlicensed band in wireless communication system - Google Patents

Abstract

The present invention relates to a method for performing license assisted access (LAA)-based communication 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 wireless communication system can perform data transmission through the unlicensed band, as well as perform data transmission/reception through the licensed band, thereby improving transmission efficiency.

Description

Field of the Invention [0001] The present invention relates to a method and apparatus for performing communication through a license-exempt band in a wireless communication system,

The present invention relates to wireless communication, and more particularly, to a method and apparatus for performing communication on a license-exempt band in a wireless communication system.

As wireless communication traffic increases, small cells such as a pico cell, a femto cell, a micro cell, a remote radio head (RRH) Although relays and repeaters are actively used, it is still an urgent problem to secure more frequencies. Accordingly, a method of performing wireless communication using unlicensed band (U-band) frequencies such as a WiFi band as well as a licensed band (L-band) is being discussed.

However, since the license-exempted band allows a competitive approach, the access method in the existing license band can not be applied as it is, and the radio frame structure in the license-exempt band can be different from the radio frame structure in the license band.

Therefore, there is a need for wireless communication technology considering support / management / operation of licensed band communication technique to smoothly support wireless communication in the license-exempted band.

The present invention relates to a method and apparatus for performing communication on a license-exempt band in a wireless communication system.

It is another object of the present invention to provide a method and apparatus for managing a license-exempt bandwidth in a wireless communication system.

It is another object of the present invention to provide a method and apparatus for utilizing license-exempt band resources under communication of licensed bands.

Another aspect of the present invention is to provide a method and apparatus for instructing a terminal to occupy a license-exempted band.

Another aspect of the present invention is to provide a method and an apparatus for monitoring a license-exempt band of a terminal.

According to an aspect of the present invention, there is provided a method of transmitting a license assisted access (LAA) based communication method in a wireless communication system supporting carrier aggregation between a serving cell in a licensed band and a serving cell in an unlicensed band . The communication method includes performing an RRC connection reconfiguration procedure for configuring a carrier wave of the license-exempt band as SCell for the UE, transmitting an activation indicator for the configured SCell to the UE, Generating channel acquisition information indicating whether to acquire a channel for the SCell based on the channel acquisition procedure and at least one of the obtained subframes, and generating the channel acquisition information on the SCell, And transmitting the data to the terminal.

According to another aspect of the present invention, there is provided a method of transmitting a license assisted access (LAA) based communication method in a wireless communication system supporting carrier aggregation between a serving cell in a licensed band and a serving cell in an unlicensed band . The method includes performing an RRC connection reconfiguration procedure to configure a carrier wave of the license-exempt band as SCell, receiving an activation indicator for the configured SCell from the base station on a first subframe, The method comprising the steps of: transitioning SCell to an active state; and receiving channel acquisition information indicating whether to acquire a channel for the SCell and at least one of the obtained subframes from the base station.

According to another aspect of the present invention, there is provided a method of performing license assisted access (LAA) based communication in a wireless communication system supporting carrier aggregation between a serving cell in a licensed band and a serving cell in an unlicensed band To the terminal. Wherein the terminal comprises a processor for performing an RRC connection reconfiguration procedure to configure a carrier wave of the license-exempt band as SCell, and an RF section for receiving an activation indicator for the configured SCell from the base station on a first subframe, And the SC unit transitions the SCell to an active state based on the activation indicator, and the RF unit receives channel acquisition information indicating whether to acquire a channel for the SCell and at least one of the obtained subframes from the base station.

According to the present invention, not only data transmission and reception can be performed through a license band in a wireless communication system, data transmission can be performed through a license-exempt band, and transmission efficiency can be increased.

Further, according to the present invention, it is possible to smoothly support the carrier aggregation between the carrier wave of the license band and the carrier wave of the license-exempt band.

1 shows a wireless communication system to which the present invention is applied.
Figure 2 shows examples of LAA deployment scenarios to which the present invention is applied.
Figure 3 shows an example of timing for an FBE according to the present invention.
4 shows an example of a flow chart of a LAA-based communication operation according to the present invention.
FIG. 5 is a diagram illustrating a case where a set of different carriers is set according to each terminal.
6 is an example of a MAC CE structure including an activation / deactivation indicator.
FIG. 7 is a diagram schematically illustrating the operation of the LAA according to the present invention in a hierarchical manner.
8 shows an example in which the UE performs preamble monitoring.
9 shows an example in which the UE performs CSI reporting according to another embodiment described above.
10 shows an example of a SCell deactivation timer related operation according to the above-described embodiment.
11 is a flowchart illustrating an example of a LAA-based communication operation performed by the LAA base station according to the present invention.
12 is a flowchart illustrating an example of a LAA-based communication operation performed by a terminal according to the present invention.
13 is an example of a block diagram illustrating an LAA-capable base station and a terminal according to the present invention.

Hereinafter, the contents related to the present invention will be described in detail with reference to exemplary drawings and embodiments, together with the contents of the present invention. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.

In addition, the present invention will be described with respect to a wireless communication network. The work performed in the wireless communication network may be performed in a process of controlling a network and transmitting data by a system (e.g., a base station) Work can be done at a terminal included in the network.

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

The wireless communication system 10 is widely deployed to provide various communication services such as voice, packet data, and the like. The wireless communication system 10 includes at least one base station 11 (evolved-NodeB, eNB). Each base station 11 provides communication services to specific cells (15a, 15b, 15c). The cell may again be divided into multiple regions (referred to as sectors).

A user equipment (UE) 12 may be fixed or mobile and may be a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, (personal digital assistant), a wireless modem, a handheld device, and the like. The base station 11 may be referred to by other terms such as a base station (BS), a base transceiver system (BTS), an access point, a femto base station, a home node B, and a relay. Cells are meant to cover various coverage areas such as megacell, macrocell, microcell, picocell, and femtocell.

Hereinafter, downlink (DL) refers to communication from the base station 11 to the terminal 12, and uplink (UL) refers to communication from the terminal 12 to the base station 11. In the downlink, the transmitter may be part of the base station 11, and the receiver may be part of the terminal 12. In the uplink, the transmitter may be part of the terminal 12, and the receiver may be part of the base station 11. There are no restrictions on multiple access schemes applied to wireless communication systems. (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA , OFDM-CDMA, and the like. A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

A carrier aggregation (CA) supports a plurality of carriers and is also referred to as spectrum aggregation or bandwidth aggregation. The individual unit carriers tied by carrier aggregation are called component carriers (CCs). A serving cell can be defined as an element frequency band that can be aggregated by carrier aggregation based on a multiple component carrier system. The serving cell includes a primary serving cell (PCell) and a secondary serving cell (SCell). The main serving cell is a single serving cell that provides security input and non-access stratum (NAS) mobility information in the establishment or re-establishment of Radio Resource Control (RRC) Quot; serving cell ". Depending on the capabilities of the terminal, at least one cell may be configured to form a set of serving cells together with a main serving cell, said at least one cell being referred to as a secondary serving cell. The set of serving cells set for one UE may consist of only one main serving cell or may consist of one main serving cell and at least one secondary serving cell.

The downlink component carrier corresponding to the main serving cell is referred to as a downlink principal carrier (DL PCC), and the uplink component carrier corresponding to the main serving cell is referred to as an uplink principal carrier (UL PCC). In the downlink, the element carrier corresponding to the secondary serving cell is referred to as a downlink sub-element carrier (DL SCC), and in the uplink, an elementary carrier corresponding to the secondary serving cell is referred to as an uplink sub-element carrier (UL SCC) do. Only one DL serving carrier may correspond to one serving cell, and DL CC and UL CC may correspond to each other.

Generally, small cell is advantageous compared to macro cell in terms of throughput that can be provided to a single terminal because small cell is served in a smaller area than macro cell. As the wireless communication traffic surges, the small cell as described above is positively utilized, but it is becoming an urgent problem to secure more frequencies in order to improve the performance.

In this regard, recently, a method for performing wireless communication using unlicensed bands such as a WiFi band as well as a licensed band has been discussed. To this end, the present invention proposes a method of performing wireless communication in a license-exempt band in consideration of support / management / operation of a license band communication technique to smoothly support wireless communication in a license-exempt band.

In the present invention, the term LAA (License Assisted Access) refers to a case where one or more SCs operating in a license-exempt band or an unlicensed spectrum based on Assisted PCell operating in a license band or a spectrum, It is a wireless communication technique that supports operation. In the LAA deployment scenario, the established SCell on the license-exempt zone may be located within macro coverage, or may be located outside of macro coverage. In addition, the set SCell on the license-exempt zone may be placed in an indoor location such as a typical household or a specific complex, or may be placed in an outdoor location. In addition, the carriers in the license and license-exempt bands may be co-location or non-co-located with respect to each other. Here, the same location means that the base station operating the carrier of the license band and the base station operating the carrier of the license-exempt band are the same base station, or the RF (radio frequency) units are located adjacent to each other.

In the case where the carriers in the license band and the license-exempted band exist at the non-co-located location, the first base station operating the carrier of the license band and the second base station operating the carrier of the license- lt; RTI ID = 0.0 > backhaul. < / RTI > Here, the ideal backhaul may refer to a backhaul having a delay of 2.5 .mu.s or less and a capacity of 10 Gbps or more. The criteria for this may vary depending on the communication environment, the wireless communication protocol, and the like.

Figure 2 shows examples of LAA deployment scenarios to which the present invention is applied.

Referring to FIG. 2, in each of the scenarios, the number of licensed carriers and unlicensed carriers may be one or more, respectively. For example, Scenario 1 is a case where a macro cell using a license carrier F1 (frequency # 1) and a small cell using a license-exempt carrier F3 are connected by a carrier aggregation (CA). In this case, the macro cell and the small cell may be non-co-located with each other and may be connected to each other with an ideal back hole. For example, the small cell may be RRH.

In another scenario scenario 2, in addition to macrocell coverage, small cell # 1 using F2 as the license carrier and small cell # 2 using F3 as the license-exempt carrier are connected to the carrier aggregation. In this case, the small cell # 1 and the small cell # 2 can be co-located with each other, and thus, an ideal backhaul can be assumed.

As another example, Scenario 3 is a case where there is a macro cell and a small cell # 1 using a license carrier F1, and the small cell # 1 and the small cell # 2 using a license-exempt carrier F3 are connected by carrier aggregation. In this case, the macro cell and the small cell # 1 may be connected to each other as an ideal or non-ideal back hole, and the small cell # 1 and the small cell # 2 may be co- ).

As another example, there are a macro cell using a license carrier F1, a small cell # 1 using a license carrier F2, and a small cell # 2 using a license-exempt carrier F3. In the scenario 4, # 2 is connected to the carrier aggregation. In this case, the macro cell and the small cell # 1 may be connected to each other as an ideal or non-ideal back hole, and the small cell # 1 and the small cell # 2 may be co-located ). If the macro cell and the small cell # 1 are connected to each other through an ideal back hole, the macro cell F1 may be connected to the small cell # 1 (F2) and the small cell # 2 (F3) by carrier aggregation .

Meanwhile, the UE can establish dual connectivity through two or more base stations among the base stations that set up at least one serving cell. A dual connection is an operation in which the UE consumes radio resources provided by at least two different network points (e.g., a macro base station and a small base station) in a RRC_CONNECTED mode. If dual connectivity is possible, a dual connection between the macrocell and the small cell (s) may be configured in the above scenarios.

Meanwhile, the regulations and standards that must be followed in order to use the license-exempt band can be defined differently by region and country. For example, the nominal channel bandwidth of the license-exempt carrier may be at least 5 MHz. In the license-exempt band, the channel bandwidth occupies approximately 80% to 100% of the nominal channel bandwidth. Thus, for the efficiency of the overall wireless communication system, the license-exempt band used in the LAA system may support a bandwidth of at least 10 MHz or 20 MHz, and may not support a bandwidth of less than 5 MHz.

Meanwhile, there are various types of contention-based channel access methods for the license-exempted band, and a channel access mechanism for the license-exempted band according to the present invention includes the following.

The channel access mechanism according to the present invention provides opportunistic channel access. A CCA (Clear Channel Assessment) is applied before the wireless communication device uses the channel for the opportunistic channel connection. This is to avoid concurrent transmissions on the same channel as other Radio Local Area Network (RLAN) systems. Here, the CCA indicates a procedure for determining whether the corresponding channel is a channel interference or a channel occupied state, that is, whether the corresponding channel is busy or idle, through energy scan or detection for the corresponding channel. The CCA can be performed based on whether or not energy is detected during a certain monitoring time. Here, the EIRP (equivalent isotropic radio power) obtained through the energy detection is compared with the predefined CCA threshold value to determine whether the corresponding channel is busy or idle. The CCA check can be performed based on "energy detection" during CCA monitoring times greater than 202.5 microseconds. The channel access mechanism according to the present invention based on the carrier sense (CS) as described above may be called LBT (Listen Before Talk).

In LBT, ECCA may be used. ECCA performs energy scanning or detection by a factor N times the duration of a factor N multiplied by a CCA observation time and determines whether the corresponding channel is channel interference or channel occupancy based on the energy scan or detection Can be expressed. Where the factor N may be a random factor. The factor N may represent the number of clear idle slots. The full idle slots result in a total idle period and need to be monitored for that idle period before starting transmission.

LBT can be divided into two types of behaviors, for example. One is FBE (Frame Based Equipment) and the other is LBE (Load Based Equipment).

The timing application in FBE and LBE will be described in detail as follows.

Figure 3 shows an example of timing for an FBE according to the present invention.

Referring to FIG. 3, the CCA performed in the FBE and the resources obtainable through the CCA are defined as a frame structure. The FBE includes an idle period and a channel occupancy time within one frame period. Where the idle period may be at least 5% of the channel occupancy time. The idle period also includes the CCA (monitoring) time. Here, the CCA time may be, for example, 202.5 占 퐏 or more. In the FBE, the CCA is performed once within a frame.

On the other hand, in LBE, unlike FBE, a specific frame structure is not used, and any time (E) CCA check can be performed when there is a demand of data transmission. In performing the ECCA check, if the channel is not occupied during N CCA times, the corresponding transmitting node (or base station) can occupy the channel. The N value is randomly selected within a predetermined interval. The N value is randomly selected in the range "1 to q value ", and the q value has a value between 4 and 32. [ Where the q value is a parameter used to determine the N value (the number of idle states after the CCA).

On the other hand, in performing the TPC (Transmit Power Control) in the license-exempt band, many wireless devices using the license-exempt band must perform at least a certain level of power control (for example, 3 dB). This allows interference between wireless devices to be controlled within the license-exempt band.

And, when using the license-exempt band, dynamic frequency selection (DFS) operation can be considered. The purpose of the DFS is to avoid interference with radar systems and achieve near-uniform resource utilization in bands such as 5 GHz. The DFS requirements are shown in the following table as an example.

Parameters Requirement DFS threshold Region Specific Channel availability check > 60 sec Channel move time <10 sec Non-occupancy time > 30 min

Such DFS requirements are based on long period values and may meet the requirements through higher layer signaling such as SCell deactivation / deconfiguration messages.

And, since many carriers within the license-exempt band can be used between various wireless communication systems, the transmitting node must be able to appropriately select some or some carriers in the license-exempt band to reduce the fairness among the wireless equipments and the interference between them . This may be referred to as a Carrier Selection operation (in the license-exempt band).

Also, the occupation of radio resources in the license-exempt band is discontinuous. For example, in Europe and Japan, it is stipulated that the occupation of radio resources in the license-exempted band should be non-continuous. In order to operate the LAA system according to the present invention based on a global single framework, ).

In the LAA system, many channels / carriers within the license-exempt band can be selected and used by the base station. For example, for the 5 GHz license-exempt band, 450 MHz in Europe and 580 MHz in the US can now be used as license-exempt bands. Therefore, a large number of carriers can be configured in the license-exempt band and can be considered for a wireless communication scheme such as CA. The above-described carrier selection can also be utilized to maintain channel usage distribution equal to efficient radio resource utilization with multiple nodes on this license-free band and with other communication technology (e.g., WiFi) nodes.

For example, a base station supporting the LAA system (hereinafter referred to as a LAA base station) may measure channels / carriers in the license-exempt band or may require the terminal to measure and report the channels / carriers in the license-exempt band. As a result, the serving cell (s) in the license-exempt band can be configured as a set of specific carriers or carriers, through RRC signaling as a potential schedulable serving cell (i.e. SCell). Of course, in some cases, the specific carrier (s) may be configured to occupy and use fixed transmission nodes. For example, access to a particular channel / carrier based on a long-term statistic, or the number of nodes performing data transmission, data load status (overload, intermediate load, The specific carrier (s) may be fixedly used, depending on the operator's policy (eg, a list of restricted channels / carriers that can be accessed) or related regulations (LBT, DFS, TPC)

In the present invention, a method of performing wireless communication in a license-exempt band is provided in order to smoothly support wireless communication in a license-exempt band, with support of a communication technique of a license band. Also, the present invention proposes how to perform resource management of the license-exempt band and how to perform wireless communication through the license-exempt band. Also, the present invention proposes a procedure and a signaling method for selecting carriers within the license-exempt band and utilizing the resources of the corresponding carriers.

4 shows an example of a flow chart of a LAA-based communication operation according to the present invention.

Referring to FIG. 4, the LAA base station performs a carrier selection operation (S400). Wherein the carrier selection includes a carrier selection operation in the license-exempt band. The LAA base station can detect the occupancy frequency and interference level of carriers (hereinafter, u-carriers) on the license-exempt band. For example, the LAA base station measures information on occupancy frequency and interference conditions of each u-carrier according to the LAA network and the WiFi network deployment environment, and measures the LAA base station and / or channel measurement report . In this case, it is difficult to grasp the short-term channel environment accurately, but the frequency of long-term use of the channel can be grasped relatively accurately.

The LAA base station may select at least one unlicensed carrier in consideration of at least one of the following criteria: For example, the LAA base station can preferentially select the idle carrier (s). In addition, the number of u-carriers to select according to traffic loading may be determined. For example, considering the various conditions such as coordination among operators, regulatory requirements, and deployment policies of an operator, the current LAA base station is available semi-staticly, lt; RTI ID = 0.0 &gt; u-carriers. &lt; / RTI &gt;

The LAA base station performs an RRC connection reconfiguration procedure with the MS (S410). The RRC connection reconfiguration procedure includes a step in which the LAA base station generates an RRC connection reconfiguration message and transmits the RRC connection reconfiguration message to the UE, and the UE transmits an RRC connection reconfiguration completion message to the LAA base station. The RRC connection reconfiguration message may be transmitted to the UE through the PCcell using the license carrier.

The RRC connection reconfiguration message may include secondary serving cell configuration information for the selected license-exempt carriers for the terminal. The RRC connection reconfiguration message may include a secondary service cell configuration information field including contents configuring the selected license-exempted carriers as secondary serving cells. The setting of the serving cell for the carrier aggregation (CA) is UE-specific.

For example, a specific CA setup may be performed according to the performance of the corresponding terminal (for example, how many CCs can be aggregated) and the number of selected carriers that can be allocated by the LAA base station. In this case, the LAA base station can independently set the CA as a set of different carriers for each MS. For reference, in this case, PCell can use the license carrier for the terminal, and SCell can use the license carrier and / or the license-exempt carrier.

Here, the CA setting will be briefly described. As shown in FIG. 5, it is assumed that a set of different carriers is set according to each terminal. FIG. 5 shows an example in which up to 16 carriers are CA set in the terminal, and it is assumed that up to 5 (no more than 5) or less than 32 carriers are allocated according to the performance of the terminal, LAA base station, May be set.

The UE1 of FIG. 5 is a terminal capable of performing CA operation on the number of carriers (for example, 16 CCs) larger than 5 CC, which is capable of supporting LAA. On the other hand, UE2 / UE3 supports LAA, but CA can be performed by combining the carrier (s) of the licensed band and the carrier (s) of the license-exempt band in less than five CCs. For example, the carrier in the license band can be set to PCell or SCell, and the carrier in the license-exempt band can be set to SCell.

Referring back to FIG. 4, the LAA base station may instruct the terminal to activate / deactivate the SCell configured with CA (S420, dotted line). In the secondary serving cell activation / deactivation procedure, the LAA base station receives an activation / deactivation indicator for activating / deactivating some or all of the secondary serving cells configured in the terminal from the base station, and the terminal transmits the activation / And may activate or deactivate some or all of the configured secondary serving cells. The activation / deactivation indicator may be received via the PCell of the license band.

According to one embodiment of the present invention, the active / inactive signaling includes an active / inactive indicator at a Media Access Control (MAC) layer for a license-exempt serving cell. The activation / deactivation indicator may be included in the MAC message and received by the terminal. The MAC message includes at least one MAC (Control Element), and the at least one MAC CE includes an activation / deactivation indicator for Scell of the license-exempt band.

Because the RRC configured serving cells are initially inactive except for PCell (i.e., SCell's), the MAC CE as shown in FIG. 6 may be used to indicate activation / deactivation of the SCell.

Referring to FIG. 6, the MAC CE may include n Ci and R fields. For example, the Ci field may include C7, C6, C5, C4, C3, C2, and C1 fields. The Ci field may indicate activation / deactivation of the corresponding serving cell based on the value of 1 or 0, respectively. For example, the C1 field indicates activation of the secondary serving cell # 1 when set to 1 and indicates inactivation of the secondary serving cell # 1 if set to 0. The R field is a reserved bit and may be set to zero. PCell and PUCCH (Physical Uplink Control Channel) SCell (SCELL with PUCCH transmission set) can always be configured to be active. In this case, since the activation / deactivation instruction is meaningless, the fields corresponding to the PCell and PUCCH SCell are R field Can be set.

According to another embodiment of the present invention, the active / inactive indication for the unlicensed serving cell may be performed without the separate MAC signaling. In this case, the base station may transmit an on / off indicator for the scell through the PHY layer to instruct activation / deactivation of the scell.

When the secondary serving cell is activated according to the present invention, the UE can perform PDCCH (Physical Downlink Control Channel) / EPDCCH (Extended PDCCH) monitoring and decoding on the secondary serving cell and perform data transmission and CSI Report and so on. On the other hand, if the secondary serving cell is deactivated, the UE does not perform PDCCH / EPDCCH monitoring and decoding on the secondary serving cell, nor does it perform data transmission, CSI reporting, and the like.

On the other hand, although a disabled serving cell may be used for a path-loss reference, the path loss reference of the disabled serving cell may be used less frequently than the active serving cell. In addition, when the secondary serving cell is deactivated, the DL CC of the secondary serving cell and the UL CC linked to the SIB (System Information Block) 2 are also deactivated, and a Physical Uplink Shared Channel (PUSCH) and a Sounding Reference Signal is also prohibited.

Meanwhile, an operation of the LAA according to an exemplary embodiment of the present invention will be schematically described according to a layer. This is shown in FIG.

Referring to FIG. 7, among the plurality of error-free carrier waves, C1 to C6 and C10 to C12 are CA-configured in the terminal and RLC layer signaling is performed, and C1 to C3 and C11 To C12 are activated, and the remaining C4, C5, C6, and C10 are deactivated. When the PHY layer operation and signaling cause the LBT to occupy C1, C2, and C11 for that terminal, and C3 and C12 are not occupied, the LAA base station and the terminal can perform LAA wireless communication operation based on the CA and the like on the license- Can be performed.

In this regard, the LAA base station performs the PHY signaling procedure to the mobile station, and the mobile station checks the PHY signaling (S430). Here, the PHY signaling may include at least one of a preamble and a (E) PDCCH transmission transmitted from PCell.

1) Preamble monitoring

If the UE receives an activation indicator for SCell (based on a license-exempt carrier) in subframe n from the LAA base station, the UE starts preamble monitoring from subframe n + m. Here, the preamble may include or indicate at least one of the channel occupancy of the corresponding SCell, the occupied position and interval of the channel, the scheduling information, and the cell ID of the corresponding SCell. M is an integer, for example, 4 or 8.

A process of performing preamble monitoring by a UE according to an exemplary embodiment of the present invention will be described with reference to FIG.

Referring to FIG. 8, SCell # 1 through SCell # 5 are configured in the terminal, and MAC signaling (activation / activation indicator included) indicating activation of SCell # 1 and SCell # 3 in subframe n from the LAA base station , The UE starts preamble monitoring from the subframe n + m (8 in this case) of SCell # 1 and SCell # 3, and does not perform preamble monitoring in the remaining SCells that are not activated.

If a terminal needs to perform preamble monitoring on all CCs configured with only RRC (i.e., CA configured), this can result in too high processing complexity and power consumption for the terminal. For example, if a maximum of 32 CCs are configured, if the terminal monitors all the CCs unnecessarily, it may be too heavy for the terminal. Considering the activation / deactivation signaling introduced for the purpose of minimizing the power consumption of the terminal, it is not proper to perform monitoring on all RRC-configured CCs.

Therefore, in order to avoid the above-described complexity and unnecessary power consumption, if the activation indicator for the specific SCell of the license-exempt band is received in the subframe n, the UE monitors the reception of the preamble on the corresponding SCell starting from the subframe n + m. That is, the UE monitors the preamble reception on the SCell indicated by the activation indicator among the set SCells to acquire the channel occupancy information due to the LBT performance, or performs radio resource management (RRM), synchronization, CSI measurement and report, automatic gain control can be performed. Here, the AGC includes adjusting power received from an antenna at an appropriate power level that can be interpreted in a terminal baseband chip according to the movement or channel environment of the terminal.

2) CSI Reporting

The terminal can perform CSI reporting on the activated SCell. The LAA base station can adjust the MCS (Modulation Coding Scheme) level and the like in performing the scheduling to the LAA terminal based on the CSI report, and can provide scheduling suitable for the channel environment. The CSI report includes channel quality in the time and frequency domain and information necessary for proper antenna processing in the case of spatial multiplexing. The CSI report may include a Channel Quality Indicator (CQI), a Precoding Matrix Index (PMI), a Precoding Type Indicator (PTI), and a Rank Indication (RI).

In one embodiment, the UE starts periodically after the subframe n + m starting the preamble monitoring described above and reaches the subframe n + X at the latest, irrespective of whether the channel is acquired (or occupied) based on the LBT of the base station. It can be performed non-periodically. If the terminal sometimes derives an erroneous CSI (especially a CQI) value (i.e., an out-of-range value is derived), the terminal reports it to the LAA base station. The X value may be defined by a timer or by a value of at least a multiple of a channel occupancy time after a subframe n + m (preamble monitoring start subframe) or by a value of RRC signaling, Can be set. The value can also have an infinite value. Therefore, the UE that has started the preamble monitoring once may be continuously monitoring the preamble before receiving the deactivation command.

In another embodiment, if the base station occupies (or acquires) a channel based on the (E) CCA after the subframe n + m for starting the preamble monitoring described above, and transmits the information to the mobile station through physical layer signaling such as the preamble If instructed, the terminal may perform a CSI report on the activated SCell from the subframe k in the occupied channel (occupied subframes). The CSI report may be performed through a serving cell (e.g., a PUCCH transmission serving cell) determined to perform CSI reporting. Here, the value of k depends on (E) occupation of the channel through the CCA operation, and includes an arbitrary value. FIG. 9 shows an example of performing CSI reporting according to an example of the present invention.

9, the UE receives an activation indicator for SCell # 1 and SCell # 3, or an indicator for cell selection (SCell on / off signaling) among a plurality of SCells configured for RRC, Here, the preamble monitoring starts from 8), and after the base station performs the (E) CCA, the CSI report starts from the subframe k in the occupied subframes. Or (E) when the CCA immediately occupied subframe starts, the CSI report can be started from the starting point k 'of the occupied subframes.

Meanwhile, the LAA base station can transmit the SCell on / off signaling to the UE. The SCell on / off signaling includes a SCell on / off status indicator indicating whether the SCell of the license-exempt band is on or off. The CSI report may be triggered when the terminal receives the above-mentioned preamble transmitted on the corresponding SCell or receives a physical channel (e.g. PDCCH) including an on state indicator for that SCell.

On the other hand, if the SCell in the license-exempt band is activated, the SCell deactivation timer for that SCell is activated. If the SCell deactivation timer expires, the SCell transitions to the deactivated state again. The deactivation timer is a value set by the base station to the UE. The deactivation timer receives an indicator (SCell on / off signaling) for an activation indicator or a cell selection in the subframe n as described above and a deactivation timer starts from the subframe n + 8 So that the UE transits the corresponding serving cell to the inactive state without an inactivation indicator at the moment when the indicated timer value expires.

In one embodiment, if the terminal receives an activation indicator in subframe n, the SCell deactivation timer for that SCell starts from subframe n + m. M is an integer and can be, for example, 4 or 8.

10 is a diagram illustrating an operation for a SCell deactivation timer according to an embodiment of the present invention.

10, when the UE receives an activation indicator for the SCell # 1 and the SCell # 3 in the license-exempt band in the subframe n, the UE transmits the activation indicator to the SCell # 1 and the SCell # 3 starting from the subframe n + m Each SCell deactivation timer for each is started. When the timer for SCell # 1 expires, SCell # 1 transitions to the inactive state. On the other hand, when the SCell deactivation timer succeeds in occupying the channel while the SCell deactivation timer is running, that is, when receiving information such as a preamble indicating that the channel is acquired based on the CCA from the LAA base station, the SCell deactivation timer for SCell # 3 Lt; / RTI &gt;

On the other hand, if the base station occupies the channel based on the (E) CCA and the channel acquisition (or occupancy) information is known to the UE through signaling such as a preamble or a PDCCH after the subframe n + m, The SCell deactivation timer for that SCell may be started from the beginning of the (or occupied) subframe.

The SCell deactivation timer is initialized (i.e., restarted) if the SCell activation indicator is received back to the terminal or channel occupancy information is received at the terminal before the expiration of the SCell deactivation timer expires. In particular, if the SCell deactivation timer already started by the activator is in operation and the UE has received channel acquisition information by the base station, the SCell deactivation timer may be restarted, thereby preventing the SCell from being inappropriately deactivated have. This is useful for indicating the channel acquisition information of the base station to the terminal through the preamble.

3) SRS (Sounding Reference Signal)

If uplink (UL) transmission is allowed in the SCell of the license-exempt band, the terminal may transmit the SRS on the corresponding SCell. For example, when the UE receives an activation indicator for the SCell in the subframe n or receives the PHY signaling, the channel is acquired based on the (E) CCA after the subframe n + m, and the channel acquisition information includes signaling such as preamble or PDCCH The SRS is triggered and transmitted in at least one subframe set in the occupied subframes. That is, the terminal having the LAA established determines the SRS transmission timing according to the state of channel occupancy of the base station or the terminal. Based on this, the SRS transmission can be performed on the SCell of the license-exempt band.

In step S420, if the SCell on / off mechanism of the license-exempt band is dynamically applied by the PHY signaling, the RRC signaling reception time or the reception time of the channel acquisition information, The above-described embodiments can be performed.

In the LAA environment without activation / deactivation signaling, it is possible to determine availability of the corresponding channel depending on the PHY signaling, and in this case, the following additional consideration can be taken in performing the PHR.

4) PHR (Power Headroom Report)

The PHR is an operation in which the UE reports the surplus power of the current UE to the BS, and the BS can perform scheduling within the idle power range. If the channel is acquired through the (E) CCA operation, then the PHR may be triggered. In this case, even if the channel is acquired on only one SCell, a PHR for all configured SCell cells may be performed. Additionally, if a serving cell group is used, the PHR for all the SCells in the serving cell group to which the channel is acquired belongs may be triggered, and the PHR for SCells in all serving cell groups may be triggered. The triggered PHR is calculated based on the difference between the Pcmax, c value of each serving cell and the calculated uplink transmission power value, and the UE reports it to the BS. Uplink / downlink communication on the occupied subframes (S440).

11 is a flowchart illustrating an example of a LAA-based communication operation performed by the LAA base station according to the present invention.

Referring to FIG. 11, the LAA base station performs an RRC connection reconfiguration procedure in which the license-exempt carriers in the license-exempt band are configured as SCells for the terminal (S1100). The RRC connection reconfiguration procedure includes a step in which the LAA base station generates an RRC connection reconfiguration message and transmits the RRC connection reconfiguration message to the UE, and the UE transmits an RRC connection reconfiguration completion message to the LAA base station. The RRC connection reconfiguration message may be transmitted to the UE through the PCcell using the license carrier. The RRC connection reconfiguration message may include secondary serving cell configuration information for the license-exempt carriers for the terminal. Information related to the present invention includes information for preamble monitoring, information on a CSI measurement subframe, information on a deactivation timer setting value, and setting information for an uplink SRS / PHR report in its configuration information in the RRC connection reconfiguration message can do.

The LAA base station transmits an activation / deactivation indicator for the SCell of the configured license-exempt band to the terminal (S1110). The activation / deactivation indicator may be transmitted through the PCell of the license band. The activation / deactivation indicator may be transmitted to the terminal through the MAC message. State.

According to another exemplary embodiment of the present invention, the LAA base station may transmit a physical channel (e.g., a PDCCH) including a SCell on / off status indicator indicating whether the SCell of the license-exempt band is on / off, have.

The LAA base station performs the CCA-based channel acquisition procedure on the SCelles of the activated license-exempt band (S1120).

The LAA base station performs a PHY signaling procedure including a preamble (or PDCCH) transmission including channel acquisition information for at least one SCell of the license-exempt band based on the channel acquisition procedure (S1130). The channel acquisition information may indicate a channel acquired SCell and subframes obtained for the corresponding SCell. Wherein the PHY signaling procedure comprises at least one of a CSI report receipt for the SCell of the at least one license-exempt band, an SRS receipt for the SCell of the at least one license-exempt band, and a PHR for the SCell of the at least one license- .

If an activation indicator for SCell in the license-exempt band is transmitted in subframe n, the LAA base station transmits the channel acquisition information on the SCell in the license-exempt band via the preamble (or PDCCH) from subframe n + m or thereafter .

In addition, the LAA base station can receive the CSI report that the UE has performed on the SCell of the license-exempt band starting from the sub-frame n + m and at the latest within the subframe n + X. Alternatively, after transmitting the channel acquisition information, the LAA base station may receive a CSI report on the SCell of the license-exempt band from sub-frame k in the occupied subframes of the SCell.

In addition, the LAA base station may receive the SRS on at least one subframe of the occupied subframes of the SCell.

In addition, the LAA base station can receive the PHR for the corresponding SCell from the terminal when the channel has the SCell of the license-exempt band. The LAA base station may also receive the PHR for the SCell of all configured license-exempt bands from the terminal.

By starting the preamble monitoring on the proposed timing, the base station receives the channel occupancy and other information (CSI report triggering, automatic gain control (AGC), synchronization, etc.) and prepares for data scheduling in the future. Likewise, the UE performs the CSI report using the proposed method, and is used for downlink scheduling after acquiring the channel of the base station in the future. Also, the SRS transmission and PHR associated with the ring in the uplink scheduling are performed from the UE through the proposed method and transmitted to the base station, and the base station uses the received SRS and PHR for future uplink scheduling.

The LAA base station performs data transmission / reception with the UE on the occupied subframes on the at least one SCell of the license-exempt band indicated by the channel acquisition information (S1140).

In this case, in step S1120, the LAA base station transmits a CCA-based channel acquisition procedure to all of the SCell configured for the UE or a part of the SCells selected according to a predetermined criterion Can be performed.

12 is a flowchart illustrating an example of a LAA-based communication operation performed by a terminal according to the present invention.

Referring to FIG. 12, the UE performs an RRC connection reconfiguration procedure in which the license-exempted carriers in the license-exempt band are composed of SCells (S1200). The RRC connection reconfiguration procedure includes the step of the UE receiving the RRC connection reconfiguration message to the LAA base station, and the UE transmitting the RRC connection reconfiguration completion message to the LAA base station. The RRC connection reconfiguration message may include secondary serving cell configuration information for the license-exempt carriers for the terminal. The secondary cell configuration information may include a frequency band and a center carrier information to which a license-exempt carrier wave is allocated. Since this is derived through the EARFCN value, the EARFCN value is included in the secondary cell configuration information, indicating which frequency band and which center carrier the secondary serving cell corresponds to.

The terminal receives an activation / deactivation indicator for the SCell of the configured license-exempt band from the LAA base station (S1210). Meanwhile, according to another example of the present invention, the terminal may receive a physical channel (for example, a PDCCH) including a SCell on / off status indicator indicating whether the SCell of the license-exempt band is on / off status.

The LAA base station performs a PHY signaling procedure including reception of a preamble (or PDCCH) including channel acquisition information for a SCell of at least one of the license-unlicensed bands in the activated license-exempt band (S1220). The channel acquisition information may indicate a channel acquired SCell and subframes obtained for the corresponding SCell. The PHY signaling procedure may perform one of the following: CSI reporting for at least one license-exempt SCell, SRS transmission for at least one license-exempt band SCell, and PHR reporting for at least one license-exempt band SCell .

More specifically, if the UE receives an activation indicator for SCell in the license-exempt band in subframe n, the UE can perform preamble monitoring on the SCell in the license-exempt band from subframe n + m or thereafter, And may receive channel acquisition information through the preamble (or PDCCH). Then, the terminal can perform CSI reporting on the SCell of the license-exempt band within the subframe n + X at the latest starting from the subframe n + m. Alternatively, after receiving the channel acquisition information, the LAA base station may perform a CSI report on the SCell of the unlicensed band from the subframe k in the occupied subframes of the SCell. In addition, the UE may transmit SRS on at least one of the occupied subframes of the SCell. In addition, if there is a SCell in the license-exempted band, the terminal can perform the PHR for the SCell in the corresponding license-exempted band. Or PHR for SCell of all configured license-exempt bands.

The terminal performs data transmission / reception with the LAA base station on occupied subframes on the SCell of the at least one license-exempt band indicated by the channel acquisition information (S1230).

In this case, in step S1220, the UE can perform preamble monitoring on all or part of the SCs selected according to the predetermined criteria, A PHY signaling procedure can be performed.

13 is an example of a block diagram illustrating an LAA-capable base station and a terminal according to the present invention.

Referring to FIG. 13, a base station 1300 includes a memory 1305, a processor 1310, and a radio frequency unit 1320. The memory 1305 is connected to the processor 1310 and stores various information for driving the processor 1310. [ RF section 1320 is coupled to processor 1310 and transmits and / or receives wireless signals. Processor 1310 implements the proposed functions, procedures, and / or methods for performing operations in accordance with the present invention. In the above-described embodiments, the operation of the base station can be implemented by control of the processor 1310. [

The processor 1310 includes a serving cell configuration unit 1311, an activation processing unit 1312, a CCA performing unit 1313, and a PHY processing unit 1314. [

The serving cell configuration unit 1311 performs the license-exempt carrier selection. The serving cell configuration unit 1311 can detect the occupancy frequency and interference level of the license-exempt carriers on the license-exempt band, and can select the license-exempt carriers to be used for the LAA operation with the terminal within the license-exclusion band.

In addition, the serving cell configuration unit 1311 may generate an RRC connection reconfiguration message including information for configuring the selected license-exempted carrier waves with the SCell for the UE, and may transmit the RRC connection reconfiguration message to the UE through the RF unit 1320. The SCell configuration information may include a frequency band and a center carrier information to which a license-exempt carrier wave is allocated. Since this is derived through the EARFCN value, the EARFCN value is included in the secondary cell configuration information, indicating which frequency band and which center carrier the secondary serving cell corresponds to. The RRC connection reconfiguration message may be transmitted via a PCell using a license carrier. RF section 1320 may receive an RRC connection reconfiguration complete message from terminal 1350.

The activation processing unit 1312 may generate an activation / deactivation indicator for the SCells of the license-exempt band configured in the terminal 1350, and may transmit the activation / deactivation indicator to the terminal through the RF unit 1320. The activation / deactivation indicator may be included in the MAC message and transmitted to the terminal through the PCell.

The CCA performing unit 1313 performs a channel acquisition procedure for the SCelles of the activated license-exempt band. The private channel acquisition procedure can be performed based on the CCA. The CCA performing unit 1313 may generate channel acquisition information for at least one SCell of the license-exempt band based on the channel acquisition procedure. The channel acquisition information may indicate the channel acquired SCell and the acquired (occupied) subframes for the SCell.

The PHY processing unit 1314 may generate a preamble (or PDCCH) including the channel acquisition information and transmit the preamble (or PDCCH) to the UE through the RF unit 1320. The PHY processing unit 1314 can control to perform CSI reporting, SRS reception, and PHR reception on the SCell of the channel-obtained license-exempt band. PHY processing unit 1314 can process and interpret the CSI report, SRS, and PHR. If the PHY processor 1314 transmits an activation indicator for SCell in the license-exempt band in subframe n, the RF unit 1320 transmits the channel acquisition information to the preamble (or PDCCH) from subframe n + m or thereafter. To be transmitted on the SCell of the license-exempt band. In addition, the PHY processing unit 1314 can control the terminal 1350 to receive the CSI report performed on the SCell in the license-exempted band starting from the sub-frame n + m and at the latest within the sub-frame n + X. Or RF unit 1320 may control to receive a CSI report on SCell of the license-exempt band from sub-frame k in occupied subframes of the SCell after transmitting the channel acquisition information. In addition, the PHY processing unit 1314 can control to receive the SRS on at least one subframe among the obtained (occupied) subframes of the SCell. In addition, the PHY processing unit 1314 can control to receive the PHR for the corresponding SCell from the terminal 1350 when the channel has the SCell of the license-exempted band. The RF unit 1320 may control to receive PHRs for the SCell of all the configured license-exempted bands from the terminal 1350. [

Accordingly, the processor 1310 processes the PHY signaling in consideration of the operation of the PHY processing unit 1314, and transmits the PHY signaling to the acquired (occupied) subframes of the SCell of the license-exempt band via the RF unit 1320 And performs scheduling so that data transmission / reception with the terminal 1350 can be performed.

Terminal 1350 includes memory 1355, processor 1360, and RF section 1370. The memory 1355 is coupled to the processor 1360 and stores various information for driving the processor 1360. RF section 1370 is coupled to processor 1360 to transmit and / or receive wireless signals. Processor 1360 implements the proposed functions, procedures and / or methods for performing the operations according to the present invention. In the above-described embodiment, the operation of the terminal can be realized by the control of the processor 1360. [

The RF unit 1370 receives the RRC connection reconfiguration message, the activation / deactivation indicator, and the channel acquisition information from the base station 1300.

The processor 1360 includes a serving cell configuration section 1361, an activation processing section 1362, and a PHY processing section 1363.

The serving cell configuration unit 1361 configures the SCs of the license-exempt band based on the RRC connection reconfiguration message. Then, the serving cell configuration unit 1361 generates an RRC connection reconfiguration completion message and transmits it to the base station 1300 through the RF unit 1370.

The activation processor 1362 transitions the SCell of the configured license-exempt band to the active or inactive state based on the received activation / deactivation indicator.

The PHY processing unit 1363 can identify the SCell acquired based on the channel acquisition information and the subframes obtained (occupied) with respect to the corresponding SCell.

In addition, the PHY processor 1363 can perform preamble monitoring on the SCell of the license-exempt band from the subframe n + m or thereafter when the activation indicator for the SCell of the license-exempt band is received in the subframe n, And to receive the acquisition information through the preamble (or PDCCH).

Also, the PHY processing unit 1363 can perform the CSI reporting on the SCell of the license-exempted band starting from the subframe n + m through the RF unit 1370 and at the latest in the subframe n + X. Or the PHY processing unit 1363 receives the channel acquisition information from the RF unit 1370 through the RF unit 1370 from the subframe k in the occupied subframes of the SCell to the CSI Reporting can be performed.

In addition, the PHY processing unit 1363 can transmit the SRS on at least one subframe among the occupied subframes of the SCell through the RF unit 1370.

In addition, the PHY processor 1363 can perform the PHR for the SCell of the corresponding license-exempted band or the PHR for the SCell of the all-configured license-exempted band through the RF unit 1370 if the channel has the SCell of the license-exempted band.

In addition, the PHY processing unit 1363 can perform data transmission / reception with the base station 1300 on the obtained (occupied) sub-frames of the SCell of the license-exempt band through the RF unit 1370.

A processor in the present invention may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and / or a data processing device. The 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 the radio signal. When the embodiment is implemented in software, the above-described techniques may be implemented with modules (processes, functions, and so on) that perform the functions described above. The module is stored in memory and can be executed by the processor. The memory may be internal or external to the processor and may be coupled to the processor by any of a variety of well known means.

Claims (11)

A method for performing communication through a license-exempt band of a terminal in a wireless communication system,
A radio resource control (RRC) connection with a first serving cell in a licensed band;
Receiving an RRC connection establishment message including information on a second serving cell in an unlicensed band through the first serving cell; Wherein the information on the second serving cell in the unlicensed band includes cell information on the license-exempt band for supporting carrier aggregation with the first serving cell,
Receiving a message including an activation / deactivation indicator for the second serving cell through the first serving cell;
Performing a channel acquisition procedure on the second serving cell; Wherein the channel acquisition procedure is to check channel interference or channel occupancy status of the second serving cell for a predetermined time;
Performing a preamble monitoring through the second serving cell in consideration of the channel acquisition procedure, performing CSI reporting, performing a SRS report, or performing a power headroom (PHR) And performing at least one of the reporting.
The method according to claim 1,
Wherein the activation / deactivation indicator is transmitted on a first subframe, the channel acquisition information is transmitted after a second subframe or after the second subframe, and the second subframe is transmitted after the first subframe, The communication method comprising the steps of:
3. The method of claim 2,
Receiving a channel state information (CSI) report for the second serving cell from the terminal on a third subframe,
And the third sub-frame is located after the second sub-frame in the time domain.
3. The method of claim 2,
And the third sub-frame is one sub-frame of the obtained sub-frames.
3. The method of claim 2,
Wherein a SRS (Sounding Reference Signal) is received from the terminal on at least one subframe of the obtained subframes of the second serving cell.
A License Assisted Access (LAA) based communication method in a wireless communication system supporting carrier aggregation between a first serving cell in a licensed band and a second serving cell in an unlicensed band,
Performing an RRC connection reconfiguration procedure for configuring a carrier of the license-exempt band with SCell;
Receiving an activation indicator for the configured SCell from the base station on a first subframe;
Transitioning the SCell to an active state based on the activation indicator; And
Receiving channel acquisition information from the base station indicating whether to acquire a channel for the SCell and at least one of the obtained subframes.
The method according to claim 6,
Performing monitoring on channel acquisition information on the SCell from a second sub-frame,
And the second sub-frame is the eighth sub-frame after the first sub-frame.
8. The method of claim 7,
Performing a CSI (Channel State Information) report on the SCell from the terminal on a third subframe,
And the third sub-frame is located after the second sub-frame in the time domain.
8. The method of claim 7,
And the third sub-frame is one sub-frame of the obtained sub-frames.
8. The method of claim 7,
And receiving a Sounding Reference Signal (SRS) from the terminal on at least one subframe of the acquired subframes of the SCell.
A terminal performing license assisted access (LAA) based communication in a wireless communication system supporting carrier aggregation between a serving cell in a licensed band and a serving cell in an unlicensed band,
A processor for performing an RRC connection reconfiguration procedure to configure a carrier of the license-exempt band as a SCell; And
And an RF unit for receiving an activation indicator for the configured SCell from the base station on a first subframe,
The processor transitions the SCell to an active state based on the activation indicator,
Wherein the RF unit receives channel acquisition information indicating whether to acquire a channel for the SCell and at least one of the obtained subframes from the base station.

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