KR20160055040A - Method and apparatus of wireless communication based on laa - Google Patents

Abstract

The present invention relates to a method and device to perform licensed assisted access (LAA)-based wireless communications in a wireless communications system. According to the present invention, it is possible to execute data transmission and reception through a licensed band in the wireless communications system and data transmission through an unlicensed band, thereby improving transmission efficiency. In addition, it is possible to smoothly support carrier aggregation between a carrier of the licensed band and a carrier of the unlicensed band.

Description

≪ Desc / Clms Page number 1 > METHOD AND APPARATUS OF WIRELESS COMMUNICATION BASED ON LAA < RTI ID =

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly, to a method and apparatus for performing wireless communication based on LAA (Licensed Assisted Access) in a wireless communication system.

Cellular is a proposed concept to overcome the limitations of service area, frequency and subscriber capacity. This is a method of switching a high-power single base station to a low-power multiple base station to provide a voice call. That is, the mobile communication service area is divided into several small cell units so that the frequency can be reused spatially. Meanwhile, a multi-element carrier system refers to a wireless communication system capable of supporting carrier aggregation (CA). Carrier aggregation is a technique for efficiently using fragmented small bands. It has the same effect as using a logically large bands by bundling a plurality of physically continuous or non-continuous bands in the frequency domain. In order to make it possible.

In certain areas, such as a hotspot inside a cell, there is a particularly high demand for communication, and in certain areas, such as the cell edge or coverage hole, the reception sensitivity of the radio wave may be reduced. As wireless communication technology develops, small cells in a macro cell, for example, a picocell (for example, a picocell), for the purpose of enabling communication in an area such as a hot spot, A pico cell, a femtocell, a micro cell, a remote radio head (RRH), a relay, and a repeater are installed together. Such a network is called a heterogeneous network (HetNet). In a heterogeneous network environment, a macro cell is a large cell with a large coverage and a small cell such as a femtocell and a picocell is a small cell.

As the wireless communication traffic surges, small cells such as the above are actively utilized, but still more frequency is becoming an urgent problem. 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 basically be different from the radio frame structure in the license band . A method of performing wireless communication in the license-exempt band is required under the support of the communication technique of the licensed band in order to favorably support the wireless communication in the license-exempted band.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wireless communication method and apparatus based on LAA.

It is another object of the present invention to provide an apparatus and method for transmitting data through a license-exempt band.

It is another object of the present invention to provide a method and apparatus for determining a start / end point of data transmission in a license-exempt band.

It is another object of the present invention to provide a method and apparatus for efficiently performing data transmission in a frame optimized for LAA-based wireless communication.

According to an aspect of the present invention, there is provided a method for performing communication by a base station in a wireless communication system supporting a LAA (Licensed Assisted Access). The method includes generating LAA configuration information for a cell using a license-exempt carrier wave using a license-exempt carrier wave, transmitting the generated LAA configuration information to a terminal on a cell using a license carrier, The method comprising the steps of: performing channel clearance assessment (CCA) on a cell, determining channel reservation information indicating occupancy of a specific frame or interval on a cell using the license-exempt carrier, Transmitting a PDCCH (physical downlink control channel) or EPDCCH (enhanced PDCCH) on a cell using the license carrier to a terminal, and transmitting the license-carrier Wherein the LAA configuration information includes at least one of CCA < RTI ID = 0.0 > And a LAA frame structure index (LAA frame structure index) in a cell using the unlicensed carrier, wherein the resource block includes at least one of time, CCA timing configuration information, CCA threshold information, LAA RS measurement timing configuration information in a cell using the license- Is located within the specific frame or section.

According to another aspect of the present invention, there is provided a method for performing communication by a terminal in a wireless communication system supporting LAA (Licensed Assisted Access). The method includes: receiving LAA configuration information for a cell using a license-exempt carrier wave from a base station on a cell using a license carrier; determining, based on the received LAA configuration information, Receiving, on the cell using the license carrier, channel reservation information indicating to occupy a particular frame or section of a cell using the license-exempt carrier wave from the base station; Receiving a physical downlink control channel (PDCCH) or enhanced PDCCH (EPDCCH) from a base station on a cell, and receiving data on a resource region of a cell using the unlicensed carrier indicated by the PDCCH or the EPDCCH, , The LAA configuration information includes CCA time, CCA timing And a LAA frame structure index (LAA frame structure index), wherein the resource area includes at least one of location information, location information, location information, location information, CCA threshold information, LAA RS measurement timing configuration information in a cell using the license- .

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 is a block diagram illustrating 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.
Figure 4 provides an exemplary representation of regional regulatory requirements in the 5 GHz license-exempt spectrum.
5 shows an example of timing for FBEs in the license-exempt band according to the present invention.
6 shows an example of a frame-based LAA frame structure according to the present invention.
7 shows another example of the frame-based LAA frame structure according to the present invention.
FIG. 8 shows another example of the frame-based LAA frame structure according to the present invention.
9 is a flowchart of an LAA communication operation according to an example of the present invention.
FIG. 10 shows an example of LAA RS transmission timing in a cell using a license-exempt carrier wave according to the present invention.
11 shows another example of the LAA RS transmission timing in the cell using the license-exempt carrier wave according to the present invention.
12 illustrates a channel reservation procedure according to an exemplary embodiment of the present invention.
FIG. 13 shows a channel reservation procedure according to another example of the present invention.
14 shows an example of a CSI report according to the present invention.
FIG. 15 is a diagram illustrating a detailed LAA frame structure according to an exemplary embodiment of the present invention. Referring to FIG.
16 shows a TDD frame structure to which the present invention is applied.
17 shows an example of the LAA frame structure according to the present invention.
18 shows an LAA frame structure including a CCA subframe structure according to the present invention.
Figures 19 through 20E illustrate examples of operations according to the remaining time and threshold time according to the present invention.
21 is a flowchart showing an LAA communication operation by the base station according to the present invention.
22 is a flowchart showing an LAA communication operation by the terminal according to the present invention.
23 is an example of a block diagram illustrating an LAA supporting 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 is a block diagram illustrating a wireless communication system. This may be a network structure of an Evolved-Universal Mobile Telecommunications System (E-UMTS). The E-UMTS system may include LTE (Long Term Evolution) and LTE-A (advanced) systems. Wireless communication systems are widely deployed to provide various communication services such as voice, packet data, and the like. In addition, the wireless communication system may support device to device (D2D) communication between the terminal and the terminal. Referring to FIG. 1, an E-UTRAN includes at least one base station (BS) 20 that provides a control plane and a user plane to a UE. A user equipment (UE) 10 may be fixed or mobile and may be a mobile station, an AMS (advanced MS), a user terminal (UT), a subscriber station (SS) It can be called a term.

The base station 20 generally refers to a station that communicates with the terminal 10 and includes an evolved Node B (eNodeB), a base transceiver system (BTS), an access point, a femto-eNB ), A pico-eNB, a home eNB, a relay, and the like. The base station 20 may provide at least one cell to the terminal. The cell may mean a geographical area where the base station 20 provides communication services, or may refer to a specific frequency band. A cell may denote a downlink frequency resource and an uplink frequency resource. Or a cell may mean a combination of a downlink frequency resource and an optional uplink frequency resource.

An interface for transmitting user traffic or control traffic may be used between the base stations 20. The source BS 21 refers to a base station for which a radio bearer is currently set with the UE 10 and a target BS 22 transmits a radio bearer to the source BS 21, Means a base station to perform a handover in order to set up a radio bearer.

The base stations 20 may be connected to each other via the X2 interface, which is used to exchange messages between the base stations 20. [ The base station 20 is connected to an Evolved Packet System (EPS), more specifically an MME (Mobility Management Entity) / S-GW (Serving Gateway) 30 via an S1 interface. S1 interface supports many-to-many-relations 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. The PDN-GW 40 is changed depending on the purpose of communication or the service, and the PDN-GW 40 supporting the specific service can be found using APN (Access Point Name) information.

Hereinafter, downlink refers to communication from the base station 20 to the terminal 10, and uplink refers to communication from the terminal 10 to the base station 20. The downlink is also referred to as a forward link, and the uplink is also referred to as a reverse link. In the downlink, the transmitter may be part of the base station 20, and the receiver may be part of the terminal 10. [ In the uplink, the transmitter may be part of the terminal 10, and the receiver may be part of the base station 20. 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.

Hereinafter, a multiple carrier system includes a system supporting a carrier aggregation (CA). In a multi-carrier system, adjacent carrier aggregation and / or non-adjacent carrier aggregation may be used, and either symmetric aggregation or asymmetric aggregation may be used. 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 a Radio Resource Control (RRC) establishment or re-establishment state. 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.

Hereinafter, a heterogeneous network will be described.

Simple cell segmentation of macro cells and micro cells makes it difficult to meet the growing demand for data services. Therefore, it is possible to operate the data service for small indoor and outdoor areas by using small cells such as pico cell, femto cell and wireless relay. Although the use of the small cells is not particularly limited, in general, the picocell can be used for a communication shadow area that is not covered only by a macrocell, an area where data service is required in a large amount, a so-called hot spot or a hotzone . A femto base station (femtoeNB) can be generally used in an indoor office or a home. In addition, the wireless relay can compensate for the coverage of the macrocell. By configuring a heterogeneous network, not only the shadow areas of the data service can be eliminated, but also the data transmission speed can be increased.

In general, small cell is advantageous compared to macro cell in terms of throughput that can be provided for a single terminal because it serves a small area compared with a macro cell. As the wireless communication traffic surges, small cells as described above are actively utilized, but it is becoming an urgent problem to secure more frequencies in order to improve the throughput. Accordingly, it has been discussed how to perform wireless communication by utilizing unlicensed bands such as a WiFi band as well as a licensed band. 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.

In the present invention, LAA (License Assisted Access) refers to a carrier aggregation operation for one or more SCell operating in a license-exempt band or license-exempt spectrum based on the assistance of PCell operating in a license band or spectrum And the like. 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. The set SCell on the license-exempt zone can also be placed in an indoor location, such as a typical house or a particular complex, or 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. If the carriers in the license and license-exempt bands are located at non-identical locations, the first base station operating the carrier in the licensed band and the second base station operating the carrier in the license-exempted band may use the ideal backhaul Ideal backhaul. Here, the ideal backhaul generally refers to a backhaul having a delay of 2.5 microseconds or less and a capacity of 10 Gbps or more, and the standard may be somewhat different depending on a communication environment, a wireless communication system, 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.

On the other hand, the nominal channel bandwidth of the license-exempt carrier may be at least 5 MHz. The nominal channel bandwidth may be declared by the manufacturer and generally the occupied channel bandwidth in the unlicensed band is between about 80% and 100% of the nominal channel bandwidth declared do. Therefore, it is practically difficult to support a frequency bandwidth of less than 5 MHz (for example, 1.4 MHz, 3 MHz) in a license-exempt band (for example, a 5 GHz license-exempt band). For the efficiency of the overall wireless communication system, the license-exempt band used in the LAA system may support only 20 MHz bandwidth. Also, the measurement performance and configuration for the license-exempt carrier may be different compared to current Radio Resource Management (RRM) performance. For example, measurements on a license-exempt carrier can use a single subframe.

If uplink transmission in an unlicensed spectrum (or band) is supported, one terminal with scheduled data transmission in that spectrum may satisfy the requirement of at least 80% of the nominal channel bandwidth, The benefit of FDM by base station scheduling is restricted.

On the other hand, there may be a variety of competition-based channel access methods for the license-exempt spectrum, and the channel access mechanism for the license-exempt spectrum 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 channel connection mechanism according to the present invention may be called a Listen Before Talk (LBT) or a carrier sense (CS).

The LBT can be applied when the radio access technology (RAT) used is co-existence with another RAT such as WiFi only, or the RAT used is the same as the RAT Channel (co-channel) phase.

When the data frame transmission in the license-exempt band is performed in units of bursts, the maximum burst length in Japan (Japan) may be set to 4 ms or less. Of course, data frame transmission may be possible for a longer period of time.

In addition, on / off durations of wireless communication devices are required to comply with LBT requirements. Thus, a short on / off cycle may be considered.

 And determines whether the channel is available for transmission based on the energy measured in that channel under the LBT protocol.

Also, with respect to a wireless communication system using such unlicensed bands, the limits of the allowed configuration of each of the smart antenna systems, including the multiple transmit chains, , And limits on multiple adjacent or non-adjacent simultaneously active carriers in several sub-bands in the 5 GHz band, Can be defined.

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

Parameters such as CCA, Extended CCA, channel occupancy time, idle period, and CCA energy detection threshold are defined as follows to meet LBT requirements .

parameter Frame-based Equipment (FBE) Load-based Equipment (LBE) CCA Energy detection for more than 20μs (Energy detection for no less than 20μs) Extended CCA time Not applicable Random factor N times CCA observation duration (Duration of a random factor N multiplied by the CCA observation time)
N is chosen randomly within the range of 1 ... q (N shall be randomly selected in the range 1 ... q), q = 4 ... 32 Channel occupancy time [1, 10] ms ≪ = (13/32) * q ms Period of children > = 5% of channel occupancy Extended CCA time CCA energy detection threshold Assuming receive antenna gain G = 0 dBi:
If EIRP = 23dBm at transmitter
Threshold ≤-73dBm / MHz
Otherwise, for max transmit power P _H
threshold = -73 (dBM / MHz) +23 (dBm) -P H (dBm)

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, a wireless communication device using a license-exempt band performs a CCA check at the end of an idle period before starting transmission on an operating channel. That is, the CCA check is performed for the CCA execution time within the idle period to grasp the occupied state of the channel. The CCA check can be performed using thresholds provided by the LBT regulations based on energy detection for CCA times greater than 20 μs.

If the wireless communication device has correctly received the packet intended for the device on the channel occupied by the previous CCA operation, the wireless communication device can immediately perform management and control frames (" E.g., ACK and Block ACK frames). The consecutive sequence of such transmissions performed without the new CCA will not exceed the maximum channel occupancy time. In this case, for multicast, the ACK transmissions of the individual devices (associated with the same data packet) will be allowed to occur sequentially.

On the other hand, in the LBE, the CCE check can be performed at any time if there is a demand for data transmission. If the wireless communication device finds that the operation channel is occupied, or if it should be used continuously for the maximum channel occupancy time, the wireless communication device can perform the extended CCA check without performing transmission on the corresponding channel. In performing the extended CCA check, the operating channel is monitored for a duration of the random factor N times the CCA time. Where N represents 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.

On the other hand, short control signaling (SCS) can be transmitted without CCA. Specifically, for example, the wireless communication device is allowed to skip the CCA and transmit an ACK / NACK after receiving the data. Of course, the time at which the short control signaling is transmitted must be a part of the maximum channel occupation time. Signals with a maximum duty cycle of 5% within the observation period of 50 ms can also be transmitted without CCA.

On the other hand, the Transmit Power Control (TPC) in the license-exempt band may be as follows.

The TPC in the license-exempt band can be used by the RLAN device to ensure that the aggregate power from a large number of devices is at least 3 dB mitigation factor. For example, it is required that the RLAN apparatus have a minimum value of at least 6 dB in the TPC range and be below a value corresponding to mean e. I.r.p. (effective isotropically radiated power) in the following table.

Frequency range [MHz] Mean e.i.r.p. limit [dBm] Mean e.i.r.p. density limit [dBM / MHz] with TPC without TPC with TPC without TPC 5 150 to 5 350 23 20/23 (see note 1) 10 7/10 (see note 2) 5 470 to 5 725 30 (see note 3) 27 (see note 3) 17 (see note 3) 14 (see note 3) Note 1: The applicable limit is 20 dBm, except for transmissions whose nominal bandwidth falls completely within the band 5 150 MHz to 5 250 MHz, in which case the applicable limit is 23 dBm.
Note 2: The applicable limit is 7 dBm / MHz, except for transmissions whose nominal bandwidh falls completely within the band 5 150 MHz to 5 250 MHz, in which case the applicable limit is 10 dBm / MHz.
note 3: Slave devices without a Radar Interference Detection function shall comply with the limits for the band 5 250 MHz to 5 350 MHz.

TPC is also used in LTE (including LTE-A) systems and can meet the above requirements in the unlicensed band. For example, TPC may be used for DL power allocation and UL power control in an LTE system. The absolute value of the power level may be used for RRM measurement or pathloss calculation and the absolute value of the power level may be indicated to the terminal via the license carrier if the LAA is considered .

On the other hand, dynamic frequency selection (DFS) operation can be considered when using the license-exempt band. The purpose of the DFS is to avoid interference with radar systems and achieve near-uniform loads in bands of 5 GHz and so on. When considering a relatively slow time scale such as seconds in the DFS procedure, the DFS requirements can be expressed in the following table.

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

Such DFS requirements may be met through higher layer procedures such as SCell deactivation / deconfiguration. This can reduce or eliminate the impact on a radio access network (RAN) layer (e.g., physical layer). It can also meet in-service monitoring requirements with base station / terminal measurements during off periods of LAA cells imposed by the LBT. That is, during a normal transfer operation, the device continuously monitors the radar signal to ensure there is no radar (signal).

If a radar signal is detected during in-service monitoring, the system will move to another available channel and close the current transmission in order to avoid interfering, Lt; / RTI &gt;

Traffic is not expected on a radar-detected channel and the radar detection channel is shut down to the unoccupied segment until it becomes available again.

If a radar signal is detected on the selected channel during transmission, the system will instruct all associated devices to stop transmitting on this channel during the channel move time. )can do. The channel travel time may be, for example, 10s.

The aggregate duration of all transmissions of that system in this channel during the channel movement time may be limited to the channel closing transmission time. For example, the channel closed transmission time may be 1 s or 200 ms. The channel closed transfer time may be set differently for different regions, for example, the channel closed transfer time may be set to 1 s in Europe and 200 ms in the US.

The current small cell on / off scheme can be reused for the DFS described above. In addition, upper layer signaling may be configured to instruct the terminals to reselect the carrier within several tens of milliseconds.

A discovery reference signal (DRS) can be used to perform synchronization and RRM on small cells during small cell on / off operation. If the DRS is configured for a cell-specific reference signal (PSS) / primary synchronization signal (PSS) / secondary synchronization in a small cell and a CSI-RS (channel state information reference signal) May be used as DRS. The timing associated with the DRS may be as follows.

The DRS is transmitted on the DL subframe or on the downlink pilot time slot (DwPTS) region of the subframe. A wireless communication system can support Frequency Division Duplex (FDD) and Time Division Duplex (TDD). In case of FDD, a carrier wave used for UL transmission and a carrier frequency used for DL transmission exist, And DL transmission can be performed simultaneously. In the case of TDD, the UL transmission and the DL transmission are always separated in time based on one cell. In the case of TDD, a special subframe may be provided to provide a guard time for mode switching between transmission and reception. The special subframe may be composed of DwPTS, a guard period (GP), and an uplink pilot time slot (UpPTS).

For DRS-based measurements, the UE includes the following DRS occasions for the cell: One DRS opportunity may include a single PSS / SSS transmission, a transmission multiple CSI-RS resource element (RE) configurations on a subframe in which the CRS is at least identical to the PSS / SSS. In this case, as an example, various CSI-RS configurations may be set on the same or different subframes. As another example, various CSI-RS configurations may be scrambled independently. As another example, a relative subframe offset between the SSS and one CSI-RS RE configuration may be set.

The DRS opportunity for a cell includes N consecutive subframes. Where N may be, for example, 5 or less.

The DRS opportunity for a cell is transmitted every M ms. For example, the candidate values of M may be 40, 80, 160, and so on.

Regulatory requirements for license-exempt zones by region may differ. For example, regional regulatory requirements in the 5 GHz band may be as shown in FIG.

Figure 4 provides an exemplary representation of regional regulatory requirements in the 5 GHz license-exempt spectrum. In FIG. 4, the bandwidth of the license-exempted bands in the 5 GHz band, LBT application, DFS / TPC application, and indoor / outdoor band are shown separately.

In addition, the following table summarizes the applicable areas based on each regulatory requirement.

Requirements
(requirement) 5150 to 5250 MHz 5250 to 5350 MHz 5470 to 5725 MHz 5725 to 5875 MHz Frequency open to indoor RLAN only) Europe, South Africa, Turkey, Brazil, China, Japan Europe, South Africa, Turkey, Brazil, China, Japan Frequency open to WAS / RLAN / FWA (frequency open to WAS / RLAN / FWA) Israel, Russia,
USA, Canada, Mexico, Korea (5100-5250), India, Singapore, Australia Israel, Russia, USA, Canada, Mexico, Korea, India, Taiwan, Singapore, Australia Europe, Russia (5650-5725), South Africa, Turkey, USA, Canada (5470-5600, 5650-5725), Brazil (5470-5590, 5650-5725), Mexico (5470-5600, 5650-5725), Japan , Korea (5470-5650), Taiwan (5470-5590, 5650-5725), Singapore, Australia (5470-5600, 5650-5725) (5725-5825), USA (5725-5850), Canada (5725-5825), Brazil (5725-5850), Mexico, China (5725-5850, light licensed) Point transmission only), India, Taiwan (5725-5850), Singapore (5725-5850) Occupied channel bandwidth Europe, Russia Europe, Russia Europe, Russia TPC Europe, Russia, USA, Canada, China, Japan, Korea, Australia Europe, Russia, Turkey, USA, Canada (5470-5600, 5650-5725), Japan, Korea (5470-5650), Australia (5470-5600, 5650-5725) Europe DFS Europe, Russia, USA, Canada, China, Japan, Korea, Australia Europe, Russia, Turkey, USA, Canada (5470-5600, 5650-5725), Brazil (5470-5725), Japan, Korea (5470-5650), Australia (5470-5600, 5650-5725) Europe (5725-5850) LBT / carrier sense Europe, Russia, Japan Europe, Russia, Japan Europe, Russia, Japan

In Table 4, frequencies in brackets within each frequency range represent the effective band in that region. In addition, in Table 4, the European Union (EU) is Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, , Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, United Kingdom and the like.

As described above, the regulations that must be followed in order to use the license-exempt band in various regions and countries are defined. In order to carry out RLAN radio communications on the various license-exempt bands mentioned above, it is necessary to follow the regulations. In particular, in some representative areas, such as the EU, the use of channel access mechanisms such as LBT (or Carrier Sense) is required for co-existence between multiple RATs (eg WiFi, LAA, etc.). In addition, Japan does not require detailed requirements such as those in LBT, but it requires carrier detection based on similar requirements before data transmission for coexistence between different RATs, Of the total length of the cable is less than 4 ms.

Consideration should be given to the coexistence of other RATs in the use of license-exempt bands in the LAA system. Thus, in designing the LAA system, the requirements in the various regulations on the license-exempt band are taken into account and are compatible with the LTE (including LTE-A) Be able to. In the LAA system scenarios described above, it is assumed that the license-exempted band is connected to the license band and the carrier aggregation (CA). Hereinafter, the PCell is the license band and the SCell is based on the license-exempt band CA.

For transmission over the license-exempt band, the LBT must first be considered. As described above, LBT includes FBE and LBE as its requirements. The present invention proposes a frame structure and a communication method for the LAA system in consideration of various requirements as described above. Hereinafter, DL transmission in a license-exempt band will be mainly described, and the present invention does not exclude UL transmission.

5 shows an example of timing for FBEs in the license-exempt band according to the present invention.

Referring to FIG. 5, when the FBE is used, the CCA check is performed on a frame-by-frame basis before starting transmission on the operating channel of the license-exempt band as described above. The CCA check starts from the end of the idle period to the CCA monitoring time and ends at the end of the idle period. For compatibility between the frame structure of the FBE and the LTE specification, the following considerations should be considered.

- fixed frame period

When referring to the current LTE frame / subframe structure, at least one subframe unit (1 ms for transmission time interval) may be the smallest unit. Therefore, although the actual channel occupancy time (COT) range can be from 1ms to 10ms as the current FBE requirement, the COT may be less than 10ms considering the LTE frame structure.

- Channel occupancy time (COT)

As a requirement of the FBE, the channel occupancy time (COT) + idle period is considered to constitute the frame period. Thus, the COT value can be determined based on the frame period value and the idle period value associated with the COT.

- idle period (IP)

As a requirement of the FBE, the idle period can have a value greater than at least 5% of the COT. If the period of the idle is variable X, the frame structure for the LAA may vary depending on the X value satisfying X > (COT * 5%).

- clear channel assessment (CCA)

It is possible to determine whether the channel is busy or idle based on whether energy detection has occurred in the corresponding channel during the CCA. 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 a CCA monitoring time of more than 20 microseconds.

Considering the above considerations, the FBE parameters used in the frame structure that can be used in the license-exempt band in the LLA system can be expressed as shown in the following table, for example.

Frame period (ms) Channel occupancy time (us) Children's term (us) CCA (us) Note One 928.7 > 71.3us (7.7% of COT, > 1 symbol) > = 20us For regulation of Japan, max burst duration shall be less than 4ms. 2 1857.4 > 142.6 (7.7% of COT),> 2 symbols > = 20us 3 2786.1 > 213.9 (7.7% of COT),> 3symbols > = 20us 4 3714.8 > 285.2 (7.7% of COT), > 4symbols > = 20us 5 4714.8 > 285.2 (6% of COT),> 4 symbols > = 20us ... ... ... > = 20us 10 9500.9 > 499.1 (5.26% of COT),> 7 symbols > = 20us

Table 5 assumes that the LTE system uses a normal CP. Of course, each actual value may differ depending on the time of each of the above elements. Although LAA system specifications can be designed based on LBT (including FBE) regulations as shown in Table 5 above, it is possible to apply or support a common LAA system specification for countries or regions without LBT regulations have.

On the other hand, LAA standard design based on LBE can be implemented unlike LAA standard design based on FBE. For example, assuming LBE in the LBT specification, unlike the FBE that periodically has the CCA or IP interval, it searches for the channel during the (E) CCA time according to the event of transmission of the actual transmission data, A method of occupying the corresponding channel and performing data transmission can be implemented with the LAA design. A more detailed design for it is proposed in method 3 described later.

Hereinafter, the LAA frame structures and the communication method in the frame structure according to the present invention will be described in detail.

Method 1. Frame-Based LAA Frame Structure and Related Operations

The following LAA frame structures can be used based on the above frame structure of the FBE.

6 shows an example of a frame-based LAA frame structure according to the present invention.

Referring to FIG. 6, the frame period of the LAA frame is 1 ms. Each frame includes a channel occupancy time (COT) and an idle period (IP), and the idle period includes a CCA. The LAA frame structure based on a frame period of 1 ms is used when there are many LAA base stations and RATs (for example, WiFi access points (APs) or STAs (stations)) around the LAA base station Co-channel), providing a channel search opportunity through a relatively large number of CCAs. Similar to LBE, it can provide fair competition opportunities compared to WiFi systems based on persistent resource exploration through CCA / CS (carrier sensing). However, the LAA frame structure based on the frame period of 1 ms as described above may reduce spectral efficiency due to frequent occurrence of CCA and idle periods, which may reduce data transmission interval.

7 shows another example of the frame-based LAA frame structure according to the present invention.

Referring to FIG. 7, the frame period of the LAA frame is 4 ms. In Japan, the maximum burst transmission length in the license-exempt band is defined to be less than 4 ms, and in consideration of this, the LAA frame structure can have 1 ms to 4 ms. Referring to the regulations on the license-exempt band in Europe, the FBE can be seen to be limited to 10ms, LBE 13ms. In other countries without this limitation, we can have a more liberal LAA frame structure.

FIG. 8 shows another example of the frame-based LAA frame structure according to the present invention.

Referring to FIG. 8, the frame period of the LAA frame is 10 ms. The frame structure having the 10 ms frame period is an environment that can be considered in an environment in which there is little competition for occupying resources both spatially and frequency resources. That is, the 10ms frame period is advantageous when there are few nodes using the license-exempted bandwidth in the vicinity. A frame structure having a 10 ms frame period can provide higher spectral efficiency because it has less idle period (IP) and CCA when compared with a frame structure having a lower frame period of 1 ms or the like. On the other hand, when using a frame structure with a 10 ms frame period, the corresponding unexpected WiFi nodes (for example, WiFi APs installed by a general user) If the channel is exposed, opportunities for occupying wireless resources may be reduced due to less CCA opportunity and time, which may result in unfair resource utilization between LAA and WiFi.

6 to 8, the IP (and CCA) is illustrated as being located in front of the CTO in each frame, but this is an example, and the CTO may be located behind the frame or in another arbitrary region . When the IP (and CCA) is positioned ahead of the CTO in each frame, it is possible to determine whether the channel is occupied or not through the CCA in the IP together with a certain criterion, and to transmit data on the CTO in the corresponding frame. Also, if IP is located after the CTO of each frame, it can determine whether the corresponding channel is occupied through the CCA in the corresponding IP, and determine whether to transmit data on the CTO in the next frame according to the information.

The LAA communication operation based on the frame structure can be performed as follows. First, a CCA is performed based on a frame structure among a plurality of LAA frame structures having a plurality of fixed frame periods (for example, 1 ms to 10 ms) to determine idle or busy And can be used for data scheduling and necessary signal transmission. Here, any one LAA frame structure among a plurality of LAA frame structures having different frame periods may be predefined and used, or an LAA frame structure (frame period) may be selected in a semi-static or dynamic manner And may be changed.

The LAA communication operation based on the frame structure according to the present invention can be specifically described as follows.

9 is a flowchart of an LAA communication operation according to an example of the present invention.

Referring to FIG. 9, the LAA base station selects an LAA frame structure for a cell using a license-exempt carrier wave (S900). The serving LAA base station may determine a corresponding cell among a plurality of LAA frame structures having a predefined fixed frame period based on the propagation environment, distribution of surrounding cells, APs and STAs / terminals, Lt; RTI ID = 0.0 &gt; LAA &lt; / RTI &gt; Here, the plurality of LAA frame structures may have different frame periods, and the frame period may have a length of, for example, 1 ms to 10 ms. If it is predefined to use only one LAA frame structure, S900 may be omitted.

Another method of constructing a frame including the CCA is to construct a frame by using a period and an offset value in the RRC signaling to set a subframe to be CCA.

The LAA base station transmits the LAA configuration information to the LAA terminal through the PCell using the license carrier (S910). The LAA configuration information may be transmitted to the LAA terminal via, for example, an RRC message. Here, the RRC message may be, for example, an RRC connection reconfiguration message. The LAA configuration information includes relevant settings and parameters for LAA configuration.

The LAA configuration information may specifically include information such as CCA (or CS) time, CCA timing configuration information, CCA threshold information. The CCA timing configuration information may include a CCA period and an offset.

Herein, the CCA time represents a period during which the CCA / CS is performed. The time during which the CCA / CS is performed can be selected in various values according to the characteristics and purpose of the packet.

The CCA timing configuration information indicates information on how many cycles and offsets the CCA is performed with. For example, it is possible to inform the UE through the CCA timing configuration information that the CCA is periodically performed on a specific OFDM symbol of a specific subframe. The offset value can be represented by a subframe or an OFDM symbol unit. Also, CCA can be performed at different times based on different cell IDs from neighbor cells. The location (or idle period including the CCA) performing the CCA in the frame structure and the CCA time duration (CCA time duration) are based on the cell ID and the subframe index included in each cell It can be determined randomly. Accordingly, it is possible to avoid the case where the neighboring cells on the synchronous network (synchronous LAA Network) perform the CCA at different times and acquire the same channel at the same time for transmission.

The CCA threshold information represents a threshold value for CCA energy detection. The threshold value may include a threshold value defined for the LBT in Table 1 described above, or may include a value selected based on rules for other regions or the like. In particular, the CCA threshold information may be set to a node performing an LBT such that a Frequency Reuse Factor may be set to 1. Therefore, the frequency utilization efficiency can be increased. The CCA threshold information may be set by the base station for CCA operation, particularly when the terminal performs UL transmission. The CCA threshold information may be defined as one value for both UL / DL, or may be defined as UL, DL. In this case, the CCA threshold information for the UL can be utilized for the CCA operation when the UE performs the UL transmission, and the CCA threshold information for the DL can be utilized for the CCA operation when the base station performs the DL transmission have. In this case, the CCA critical information for the UL and the CCA critical information for the DL may indicate independent threshold values. Also, for the purpose of interference coordination between LAA nodes, the thresholds used by the base station / terminal for the CCA may be shared among the LAA nodes. For example, thresholds for CCA may be shared between LAA nodes operated by different operators or between LAA nodes operating in the same operator but connected to different Macro base stations.

In addition, the LAA configuration information may further include LAA (reference signal) measurement timing configuration information in a cell using the license-exempt carrier wave. The LAA RS measurement timing configuration information includes information about the timing associated with the LAA RS in the cell using the license-exempt carrier wave.

On the other hand, if a specific LAA frame structure is selected in the S900 procedure, an LAA frame structure index indicating the selected frame structure may be included in the LAA configuration information.

The LAA terminal performs channel measurement in the cell using the license-exempt carrier wave based on the LAA configuration information received from the LAA base station (S920). The LAA terminal may perform RRM / CSI / interference measurement, synchronization, and the like in a cell using the license-exempt carrier wave. The LAA terminal may perform the channel measurement and synchronization based on the LAA RS measurement timing configuration information. This operation may be performed by the UE according to the channel interval occupied by the LAA base station and the indication information therefrom. The LAA terminal may transmit a measurement report containing measurement results to a LAA base station via a cell (e. G., PCell) using a license carrier.

For example, LAA RS measurement timing configuration information can be utilized for channel measurement and synchronization. The LAA RS measurement timing configuration information includes information about the timing associated with the reference signal in the cell using the corresponding license-exempt carrier wave, and the LAA RS transmission timing indicated by the LAA RS measurement timing configuration information is occupied by the LAA base station May be transmitted only on the DL subframe and the DwPTS subframe and the partial subframe during the COT. Thus, the LAA base station can be kept completely off during the time when data transmission is not performed.

FIG. 10 shows an example of LAA RS transmission timing in a cell using a license-exempt carrier wave according to the present invention.

Referring to FIG. 10, the LAA BS transmits the LAA RS only on the DL subframe, the DwPTS subframe and the partial subframe during the COT occupied by the corresponding base station, and remains off for the rest of the time.

Also, the transmission to the LAA RS in the cell using the license-exempt carrier may be performed immediately in accordance with the LAA RS occasion established on the channel acquired through the LBT similar to the data transmission in the cell using the license-exempt carrier have. In this case, additionally, the LAA RS transmission can be performed based on the short control signaling of the LBT. Therefore, unlike FIG. 10, the LAA RS can be transmitted without a CCA at a predetermined time regardless of whether a cell using a license-exempted carrier is on or off. And, if the RS is defined in the existing LTE on the occupied channel for data transmission of the corresponding transmission node, the RSs can be transmitted together.

11 shows another example of the LAA RS transmission timing in the cell using the license-exempt carrier wave according to the present invention.

Referring to FIG. 11, regardless of whether a cell using a license-exempt carrier wave is on or off, LAA RS transmission can be performed at regular intervals. In this case, the LAA RS may be a signal having a maximum duty cycle of 5%, for example, within an observation period of 50 ms. That is, only when the LAA RS has a maximum duty cycle of 5% within a monitoring period of 50 ms, the LAA RS transmission may be performed at regular intervals regardless of whether the cell using the license-exempt carrier is on or off have.

Referring again to FIG. 9, the LAA base station performs CCA (or CS) on the license-exempt cell (S930). The LAA base station can determine whether the serving cell is in a channel interference or channel occupation state based on the CCA. That is, the LAA base station can determine whether the frame on the serving cell is busy or idle based on the CCA for LBT performance. The LAA base station performs CCA based on the CCA time, CCA timing configuration information, and CCA threshold information, determines that the frame associated with the CCA is busy if the detected energy is greater than a threshold value, Is smaller than a threshold value, it is determined that the associated frame is in an idle state. The time information for how much additional time it was under a particular condition (i.e., how long the detected energy is less than or greater than the threshold) in addition to the threshold value can also determine if the state of the channel is idle have. If the associated frame is in the idle state, the LAA base station can occupy that frame.

The LAA base station performs a channel reservation procedure to notify neighboring nodes (e.g., other LAA base stations or terminals) that the LAA base station occupies the frame when the frame associated with the CCA is in an idle state (S940).

For example, the LAA base station transmits channel reservation information through a preamble signal transmission defined on a cell using a license-exempt carrier so that adjacent nodes can recognize that the frame occupies the frame. In this case, the preamble signal may be transmitted in the COT of the cell using the corresponding license-exempted carrier and / or after the CCA is performed, in a state that the cell using the corresponding license-exempted carrier is idle. In this case, the preamble signal may be transmitted only when a channel reservation procedure is performed in order to increase the spectral efficiency.

12 illustrates a channel reservation procedure according to an exemplary embodiment of the present invention.

Referring to FIG. 12, the LAA operator (or LAA base station) # 1 transmits a CCA message to the terminal 1 to perform communication on the cell using the license-exempt carrier wave. In the case where the small cell using the license- And transmits the preamble to the LAA supporting nodes and the terminal 1. [ The macro operator (or macro base station) transmits the small cell on / off signaling to the terminal 1. The small cell on / off signaling includes a small cell on / off status indicator indicating whether the unofficial small cell is on / off. This is to allow the terminal 1 to perform the receiving operation on the small cell using the corresponding license-exempt carrier wave. The small cell on / off signaling may be transmitted through a physical layer signal (for example, a physical downlink control channel (PDCCH)). The physical layer signal may be mapped on a common search space and transmitted.

The preamble signal may carry some information in the same manner as a signature without carrying much information, such as, for example, RS type signaling. The preamble signal may support a plurality of transmission nodes to support multiplexing using a code / frequency / time domain.

The preamble signal may include or indicate at least one of an LAA frame structure index, license-exempt SCell activation / deactivation information, time occupied for data transmission, UL grant information for CSI reporting, and cell ID. The information included in the preamble signal may be used instead of the RRC message including the setup information for performing the CCA.

The license-exempt SCell activation / deactivation information may explicitly indicate the activation / deactivation status of the license-exempt SCell and may be activated / deactivated of the license-exempt SCell implicitly via other signals (eg CRS, PSS / SSS or CSI-RS) State. The time occupied for the data transmission may indicate, for example, the data burst length. The UL grant information for the CSI report may indicate, for example, a PUSCH on the PCell. The UL grant information for the corresponding CSI report can be triggered with the help of PCell, so it is not mandatory information, but can be used as additional signaling for triggering CSI reporting. For example, a terminal that has received a preamble indicating channel reservation can automatically trigger CSI reporting. The cell ID may provide neighbor nodes with information on which cell performs the channel reservation procedure. Also, the terminal can know which transmission point has performed the channel reservation procedure through the information through the preamble. This is especially important when TM10 (transmission mode 10) supporting Coordinated Multipoint (CoMP) is set in the corresponding UE.

Meanwhile, in another example of the channel reservation procedure of S940, the LAA base station instructs the LAA terminal to perform channel reservation for data transmission through dynamic small cell on / off signaling, and the LAA terminal includes channel reservation information for neighboring nodes (Preamble signal) such as a preamble signal or a beacon signal on a cell using a license-exempt carrier wave. Accordingly, neighboring nodes can recognize the channel reservation information of the LAA base station, which is a transmitting node, and can prevent unnecessary CCA performance and interference due to transmission.

The small cell on / off signaling and preamble signal may include or indicate at least one of an LAA frame structure index, a time occupied for data transmission, and a cell ID. The information included in the preamble signal may be used instead of the RRC message including the setup information for performing the CCA.

FIG. 13 shows a channel reservation procedure according to another example of the present invention.

13, the LAA operator # 1 (or the WLAN AP) transmits a small cell on / off signaling to the terminal 1 when the unauthorized small cell is in the idle state as a result of the CCA. The small cell on / off signaling includes a small cell on / off status indicator indicating whether the small cell using the license-exempt carrier is on / off. The small cell on / off signaling may be transmitted on PCell. Based on the on / off signaling, the terminal 1 can transmit a preamble signal to neighboring LAA operators, WLAN APs, and terminals on a cell using a license-exempt carrier wave. If the UE 1 can perform the WiFi function, it receives the small cell on / off signaling from the LAA base station, and further receives and transmits an RTS / CTS signal to recognize that the corresponding channel is occupied by the WLAP APs and STAs. The occupation state of the channel can be recognized.

Referring back to FIG. 9, when the channel reservation procedure is completed, the LAA terminal automatically triggers the CSI report and performs CSI reporting (S950). This is because a hidden node problem can potentially occur during a channel reserved interval. The LAA base station can provide scheduling suitable for the channel environment to the LAA terminal based on the CSI report.

14 shows an example of a CSI report according to the present invention.

Referring to FIG. 14, since each of the UEs is located in a different channel environment, the UEs may be in a channel environment having strong interference from other adjacent transmission nodes (for example, other AP / LAA base stations) That is, hidden node problems can potentially occur during the channel reserved time period. In order to avoid such a problem, the UE can perform the aperiodic CSI report through the license carrier (for example, PCell) after receiving the preamble or completing the channel reservation procedure with the base station. The base station can provide scheduling suitable for the channel environment to each UE on the reserved channel through instantaneous channel / interference information acquired based on the CSI report.

Referring again to FIG. 9, the LAA base station and the LAA terminal perform data transmission and reception during a reserved interval of a cell using a license-exempt carrier (S960). In this case, the neighbor nodes receiving the channel reservation information in S940 interprets the transmission intention of the LAA base station as a transmission node, and recognizes that the LAA base station reserves channel reservation for a certain period in a cell using the license-exempt carrier. The LAA terminal associated with the corresponding LAA base station expects to receive data during the corresponding reserved interval on the cell using the license-exempt carrier. In order to receive the data, the LAA terminal monitors PDCCH / EPDCCH (Enhanced PDCCH) reception on a preset serving cell similar to cross-carrier scheduling. The predetermined serving cell may be a PCell using a carrier using a license carrier, or a SCell using a carrier using a license carrier.

FIG. 15 is a diagram illustrating a detailed LAA frame structure according to an exemplary embodiment of the present invention. Referring to FIG. FIG. 15 assumes a case where a PC band of the license band (L-band) and a carrier aggregation (CA) of the SCell of the license-exempt band (U-band) are configured.

Referring to FIG. 15, a transmitting node (e.g., LAA base station) performs CCA (or CS) for data transmission on the license-exempt band. Here, the basic frame period for performing the CCA for checking whether the channel is utilized before the transmission node acquires the channel is set to 1 ms. This is to maintain fairness in acquiring radio resources with other RATs. Because transmitting nodes such as WiFi APs using the license-exempt band continuously search for idle or busy channels by certain rules (eg, NAV, energy detection, etc.) The probability of acquiring a channel (radio resource) decreases as the period of the CCA time for evaluating the availability of the channel in the frame structure for the LAA becomes longer (for example, 10 ms frame period), and the performance of the LAA This can be done.

If the transmitting node senses an idle channel on the license-exempt band, it performs channel reservation procedure and provides the length and other information for resources (e.g., time) to be occupied by the transmitting node to the neighboring nodes. Through this process, it is possible to inform the neighboring LAA base station or the UEs that the UL transmission is permitted that the corresponding channel is reserved. In this case, the frame structure may be changed to a frame structure for data transmission and may be different from the frame structure established for CCA. For example, the frame period for data transmission may be longer than the frame period for CCA. FIG. 15 shows that a transmitting node performs data transmission on a frame structure having a 4-ms data burst length for data transmission.

The terminal may perform data reception on the license-exempt band (SCell) based on the PDCCH / EPDCCH received on the license band (e.g. PCell).

Method 2. LAA frame structure and related operation based on TDD UL / DL configuration

According to the present method, the UL subframe is utilized within the TDD UL / DL configuration for IP / CCA. The TDD UL / DL configuration is shown in the following table.

Uplink- downlink
configuration Switch-point
Periodicity Subframe number 0 One 2 3 4 5 6 7 8 9 0 5ms D S U U U D S U U U One 5ms D S U U D D S U U D 2 5ms D S U D D D S U D D 3 10ms D S U U U D D D D D 4 10ms D S U U D D D D D D 5 10ms D S U D D D D D D D 6 5ms D S U U U D S U U D

In Table 6, D denotes a downlink subframe, U denotes an uplink subframe, and S denotes a special subframe. As shown in Table 2, subframes 0 and 5 are always allocated for downlink transmission, and subframe 2 is always allocated for uplink transmission. As shown in Table 2, the positions and the numbers of the downlink subframe and the uplink subframe in one radio frame are different from each other for each uplink-downlink setting. The amount of resources allocated to the uplink and the downlink transmission can be reduced asymmetrically through various UL / DL configurations. To avoid severe interference between the downlink and uplink between cells, neighboring cells generally have the same UL / DL configuration.

The point of time when the downlink is changed to the uplink or the time when the uplink is switched to the downlink is referred to as a switching point. The switch-point periodicity refers to a period in which switching between the uplink subframe and the downlink subframe is repeated in the same manner, and is 5 ms or 10 ms. For example, in the UL / DL configuration 0, D-> S-> U-> U-> U is switched from the 0th to the 4th subframe, and from the 5th to the 9th subframe, -> S-> U-> U-> U. Since one subframe is 1 ms, the periodicity of the switching time point is 5 ms. That is, the periodicity at the switching time point is smaller than one radio frame length (10 ms), and the aspect of switching in the radio frame is repeated once.

The UL / DL configuration shown in Table 6 can be transmitted from the BS to the MS through the system information. The base station can notify the UE of the change of the uplink-downlink allocation state of the radio frame by transmitting only the index of the UL / DL configuration every time the UL / DL configuration is changed. Or the UL / DL configuration may be broadcast information and control information transmitted in common to all terminals in a cell through a broadcast channel.

On the other hand, the TDD frame structure used in the license band is as follows.

16 shows a TDD frame structure to which the present invention is applied.

Referring to FIG. 16, one radio frame has a length of 10 ms and includes 10 subframes. One subframe has a length of 1 ms and includes two consecutive slots. In the case of TDD, uplink and downlink transmission are always separated in time based on one cell. Since the same carrier is used for uplink transmission and downlink transmission, the base station and the terminal repeatedly switch between the transmission mode and the reception mode. In case of TDD, a special subframe may be provided in subframe # 6 according to the configuration of the first subframe and the TDD UL / DL to provide a guard time for mode switching between transmission and reception. As shown, the special subframe may consist of a DwPTS, a guard period (GP), and an UpPTS. The DwPTS is used for initial cell search, synchronization, or channel estimation in the UE. UpPTS is used to synchronize the channel estimation at the base station and the uplink transmission synchronization of the UE. The protection period is necessary to avoid interference between the uplink and the downlink, and neither the uplink transmission nor the downlink transmission is performed during the protection period.

A new frame structure for the LAA can be defined by changing the frame structure according to the TDD UL / DL structure as described above.

For example, in the frame structure for the LAA according to the present invention, the portion corresponding to the UL subframe within the TDD UL / DL configuration is referred to as a CCA, a guard time (for switching between reception and transmission), a back- Or other signaling (eg preamble signal) and so on. Here, backoff means that, even if the channel is judged to be in an idle state to maintain fairness with a WiFi signal, an operation of occupying the channel when it is determined that the channel is not idle for a predetermined time It is time information about how long to wait when performing.

17 shows an example of the LAA frame structure for the downlink according to the present invention.

Referring to FIG. 17, in the frame structure according to the TDD UL / DL structure, the LAA frame according to the present invention transforms adjacent special subframes and / or uplink subframes to generate DwPTS, CCA, And provides a preamble transmission interval. That is, the idle period, the DwPTS, the CCA, and the preamble are included in place of the adjacent special subframe and / or uplink subframe. However, the above intervals can be defined in other subframes. Although FIG. 17 shows the TDD UL / DL configuration 5, the LAA frame structure according to the present invention can be applied to other TDD UL / DL configurations other than the TDD UL / DL configuration 5. FIG. The CCA is used for energy detection (or carrier sense) and the preamble is used for channel reservation procedures. In the license-exempt channel considering both the downlink and the uplink, the above-mentioned intervals are defined in both the beginning of the downlink and the beginning of the uplink.

The advantage of the above method is that it has the possibility of recycling the existing TDD frame structure without major changes. The LAA frame according to the present invention is not different from the existing TDD UL / DL configuration 5 when viewed on the basis of a subframe in which DL transmission is actually possible. Therefore, it is possible to support LAA communication without a large influence on channels / signals in the LTE standard transmitted on the DL. In this case, even when the PCell is set to TDD, the existing cross-carrier scheduling scheme can be applied to perform cross-carrier scheduling for the SCell on the license-exempted band. That is, introduction of a new cross-carrier scheduling scheme for LAA is not required.

As another example, it is possible to define a CCA subframe configuration for performing a CCA in the LAA frame structure or performing other transmission as in the conventional special subframe configuration. The following table shows an example of a CCA subframe configuration.

CCA subframe configuration normal CP (cyclic prefix) in Downlink CCA Idle period DwPTS 0 One OFDM symbol

X μs

Y μs One Two OFDM symbol 2 Three OFMD symbol 3 Four OFDM symbol 4 Five OFDM symbol ... ... ... ...

Table 7 shows CCA subframe configurations according to an aspect of the present invention. A CCA time, an idle period, and a DwPTS period may be defined according to each CCA subframe configuration. Can be used within 1 to 3 OFDM symbols as CCA time. This is because one OFDM symbol period in the normal CP is 71.3 mu s. Of course, more than 3 OFDM symbols may be used as time for CCA.

The CCA time is included in the idle period, and the CCA is present and remaining in the idle period can be used for signals (e.g., preamble, guard time, backoff time or other RS) for other purposes.

18 shows an LAA frame structure including a CCA subframe structure according to the present invention.

Referring to FIG. 18, subframes # 1 and / or # 6 of the LAA frame include a CCA subframe. Each CCA subframe includes CCA, IP, and DwPTS. Specifically, the CCA is located within the IP. CCA, IP and DwPTS lengths of the CCA subframe are indicated based on the CCA subframe configuration information according to the present invention described above. Of course, the subframe in which the CCA is performed is not limited to the above subframe. This is because the CCA subframe can be located according to the length of the fixed frame defined in the FBE-LBT.

In order to implement the above scheme, the UE may be instructed to configure the CCA, IP, DwPTS, and DL subframes within a frame that the BS selects or assumes. Further, information on the CCA subframe structure and on which subframe the corresponding CCA is located may be provided to the terminal by the base station. Accordingly, the UE can perform operations such as CCA and data transmission on the license-exempt band based on the configuration information of the same LAA frame as the base station.

In addition, a plurality of LAA frame structures according to the present invention may be dynamically changed through dynamic signaling similar to enhanced interference mitigation and traffic adaptation (eIMTA) to change the position of a subframe where a CCA is located. As described above, in order to coexist fairly with other RATs, the CAA execution time in the LAA system needs to be adjusted appropriately. Therefore, if the CCA is semi-statically allocated in the LAA frame structure as shown in FIG. 18, it is expected that the LAA performance will be degraded due to data transmission delay caused by WiFi as well as other transmission devices. Therefore, the LAA frame structure can be changed more dynamically according to the environment of the peripheral node and the loading of the cell. In this way, not only efficient control of radio resources on the license-exempt band but also coexistence with surrounding nodes can be greatly facilitated.

Method 3. Load-based LAA frame structure and related operations

This method is designed in consideration of LBE in the LBT. In this method, unlike the methods 1 and 2, it is not assumed that the structure of a specific frame repeatedly appears, and the channel is acquired (occupied) And transmitting the data. This method is particularly capable of supporting proper coexistence on the license-exempt band of the LAA system and the WiFi system. Also, if considering UL transmission from the terminal, to determine the extended CCA (Extended CCA, ECCA) time considered in this method, the base station should notify the terminal of (E) CCA monitoring time, number of CCAs, number of occupied subframes And may provide the terminal with an RRC message including information on at least one. The RRC message may be an RRC connection reconfiguration message. The number of CCAs represents the number of consecutive CCAs in ECCA. That is, the ECCA time is a random factor N times the duration of the CCA monitoring time. The N may be randomly selected within a range of 1 ... q each time, and the q may be set to a value of 4 to 32. [ The number of occupied subframes may correspond to, for example, (13/32) * q ms, the number of subframes for ECCA conforming to the above-mentioned LBT specification.

In the process of occupying resources between the WiFi AP / STA and the LAA base station, the following cases may occur.

First, in the first case, the LAA base station grasps the idle state through ECCA execution, and then considers the backoff time or the idle time (WiFi standard distribute interframe space (DIFS) or short interframe space (SIFS) time) If the remaining period in the LAA sub-frame of the LAA sub-frame is greater than a certain reference (critical) time, the ECA operation continues without going to the channel occupancy and data transmission step, If the remaining time in the frame is smaller than the threshold time, the process proceeds to the channel occupancy and data transmission step. This is because, in the wireless communication system according to the present invention, scheduling and data transmission from the middle of the subframe are substantially impossible, so that the WLAN STA can not be used without being occupied unnecessarily, thereby increasing the spectral efficiency of the entire frequency band to be. The threshold time may be set by the base station or a specific value may be defined in advance in the standard.

19 to 20E show examples of operations according to the remaining time period and the threshold time. FIG. 19 shows an example in which the remaining period is larger than the critical time, and FIG. 20A shows an example in which the remaining period is smaller than the critical time.

Referring to FIG. 19, ECCA is performed in one LAA subframe to determine whether the corresponding channel is in an idle state, and the remaining time can be defined as a remaining period. In FIG. 19, since the remaining time is longer than the threshold time, the LAA base station continues performing the ECCA.

On the other hand, in FIG. 20A, the remaining period is smaller than the critical time. In this case, the LAA base station performs a channel reservation procedure for the purpose of channel occupancy, and can perform data transmission on the occupied channel of the license-exempt band to the LAA terminal.

Meanwhile, when a preamble is transmitted for the channel reservation procedure, the time allocated for the preamble transmission may be equal to or longer than a period of one OFDM symbol and equal to or less than the critical time as shown in Equation (1).

When the threshold time is set by the base station, the base station may arbitrarily select the threshold time or may select based on the COT. For example, the base station may change the threshold time value depending on the COT depending on the COT.

In the meantime, a signal such as a preamble signal (or a beacon signal) can be transmitted on the license-exempt band within the remaining period. More than 80% of the total bandwidth BW can be occupied by the corresponding node for the actual transmission in accordance with the above-mentioned LBT regulation, and the signal can be transmitted on the occupied band. The signal may provide the terminal with the following operations and information in various forms.

(E.g., Cell ID) of the reservation node reserved for channel occupancy, scheduling information from the next subframe, information about how many subframes are to be occupied by the corresponding node, Channel reservation information, RRM / synchronization / CSI measurement / AGC (automatic gain control).

In another embodiment, a transmitting node (assuming a base station) that performs an LBT based LBE performs the ECCA as described above and confirms that the channel is in an idle mode, can do. However, if reference is made to the provisions for the CCA section within the current LBT specification, the channel occupancy time may be smaller than the OFDM symbol interval of the LTE system. Therefore, the transmission nodes that perform LBE-based LBT can obtain the channel after evaluating the channel occupancy through (E) CCA, not only the boundary of the subframe but also the OFDM symbol boundary . Therefore, in order to occupy the corresponding channel, the transmitting node can transmit a channel reservation signal for occupying the channel at any time before performing the Tx data / control signal transmission.

The channel occupancy signal may include a signal in the form of a preamble or a beacon described above. In addition, since it is necessary to transmit a channel occupancy signal for a partial OFDM symbol interval smaller than the above-mentioned one OFDM symbol interval, the transmitting node can generate an arbitrary signal and transmit the signal, May be transparent to the node (eg UE). However, after ECCA is performed at an arbitrary instant in one subframe (eg, an arbitrary moment between OFDM symbols # 0 and # 13 in a normal CP), the channel is acquired and data transmission and reception are performed at an arbitrary instant. (Eg, TBS decision, RE mapping, rate-matching, and so on) on the terminal side, time / frequency channel estimation block, synchronization, data / control signal decoding block, etc. Complexity) and can also make the specification more complex.

Therefore, the proposed embodiment not only solves this problem, but also discusses how to increase the data frequency efficiency.

FIG. 20B shows an example of how to determine the start and end points of a Tx data / control signal transmission based on a plurality of candidate OFDM symbols (assuming a maximum channel occupancy time of 4 ms).

Referring to FIG. 20B, a partial subframe occupies a channel in a first subframe that succeeds in occupying a channel, and transmits a Tx data / control signal at a start point of transmission of a Tx data / control signal, A subframe in which occupancy ends is generated at an arbitrary point in a subframe other than a subframe boundary. For example, a specific embodiment of the partial sub-frame may have the same structure as the first sub-frame 2000 and the last sub-frame 2001 in FIG. 20B, respectively.

The data / control signals in the partial subframe may be determined to be transmitted within the partial subframe after the LBT is performed, or after the channel reservation signal has been transmitted for channel occupancy purposes or in the end of channel occupancy have. However, exceptionally, if the time of acquiring the channel after the LBT is the subframe boundary, the Tx data / control signals may be transmitted immediately without transmitting the channel occupancy signal.

A regular subframe may be defined as a subframe in which the start and end of transmission of Tx data / control signals are performed at a subframe boundary. For example, a specific embodiment of the regular subframe may have the same structure as the second subframe to the fourth subframe 2010, 2011, 2012 in FIG. 20B. The Tx data / control signals may also be signals including at least PDCCH / PDSCH / EPDCCH or PDCCH / PDSCH or PDSCH / EPDCCH or PDSCH or EPDCCH in the case of downlink. In the case of the uplink, a guard period for uplink / downlink conversion may be additionally considered in the intervals required for performing the LBT. However, the method of determining the start and end points of transmission of the actual uplink Tx data / control signal may be the same as that of considering only the downlink.

First, as shown in FIG. 20B, candidate OFDM symbol positions for starting and ending a plurality of Tx data / control signals on the u-carrier are determined for the base station and the terminal.

As an example, possible candidate symbol (start point) positions for starting the Tx data / control transmission can be determined based on the number of OFDM symbols for the LTE TDD DwPTS.

Table 8 is an example of possible candidate symbols (start point or end point) positions for starting the Tx data / control transmission in the partial subframe using the normal CP.

Number of candidate OFDM symbol indexes of Tx data / control signal transmission Tx data / control signal transmission start / end OFDM symbol index 2 3, 9 3 3, 8, 11 4 3, 5, 8, 11

Table 9 is an example of possible candidate symbols (start point or end point) positions for starting the Tx data / control transmission in the partial subframe using the extended CP.

Number of candidate OFDM symbol indexes of Tx data / control signal transmission Tx data / control signal transmission start / end OFDM symbol index 2 3, 7 3 3, 7, 9

The values in the table are exemplary only and are not limited to those values, and index values associated with a number of more than four candidate OFDM symbol indices may be applied.

Assuming that the OFDM symbol index in one subframe is 0 to 13 (14 symbols in total), the BS and the UE acquire the channel through the LBT in the partial subframe and then transmit the pure Tx data / control Each of the plurality of candidate OFDM symbol indices may be selected for start and end of signal transmission. Of course, if the candidate symbol index is fixed to only one index value, the frequency efficiency of data transmission may not be good depending on the time of acquiring the channel, but the implementation can be facilitated. Thus, the number of candidate symbol indices greater than one has a trade-off between frequency efficiency and implementation complexity. The number of candidate symbols and corresponding indexes may be defined in advance or may be set through the RRC reset procedure.

Meanwhile, as shown in Table 8, the starting OFDM index of the Tx data / control signal is calculated by considering the number of OFDM symbols for the DwPTS according to the special subframe setting defined in the current LTE TDD, If the index of the candidate symbol is determined to be equal to the number of OFDM symbols for transmission of the control signal, the processing procedure for the data / control signal transmitted on the existing DwPTS can be maximally reused, thereby facilitating implementation.

As another example, possible candidate symbol (start point) positions for starting the Tx data / control transmission can be determined based on a setting with uniform spacing in one subframe.

Table 10 is an example of possible candidate symbols (start point or end point) positions for starting the Tx data / control transmission in the partial subframe using the normal CP.

Number of candidate OFDM symbol indexes of Tx data / control signal transmission Tx data / control signal transmission start / end OFDM symbol index 2 4, 9 3 3, 7, 10 4 3, 5, 8, 11

Table 11 is an example of possible candidate symbols (start point or end point) positions for starting the Tx data / control transmission in the partial subframe using the extended CP.

Number of candidate OFDM symbol indexes of Tx data / control signal transmission Tx data / control signal transmission start / end OFDM symbol index 2 4, 8 3 3, 6, 9

Unlike Tables 8 and 9, Tables 10 and 11 are based on candidate symbol positions uniformly distributed in one subframe, not based on the number of OFDM symbols equal to the DwPTS interval in the TDD special subframe . This method is also utilized as an OFDM symbol index for starting and ending transmission of a pure Tx data / control signal except channel occupancy signal transmission based on at least one candidate symbol index.

As another example, positions of possible candidate symbols (start point or end point) for starting the Tx data / control transmission may be determined by using an OFDM symbol index determined according to the number of candidate OFDM symbol indexes within {1,2,3} (Or end point) of Tx data / control signal transmission on the basis of the selected OFDM symbol index after the step of performing channel occupation through the LBT operation.

The candidate symbol positions determined through the above assumptions are used as the starting and ending points of the Tx data / control signal transmission.

Referring to FIG. 20C, channel occupation is performed until the position of the next candidate symbol immediately after the acquisition of the channel through ECCA in the candidate symbol positions determined in the partial sub-frame 2020 (assuming three candidate OFDM symbol indexes) Signal is transmitted. If the channel acquisition point is equal to the candidate symbol boundary, the channel occupancy signal may not be transmitted.

As shown in FIG. 20C, the base station obtains a channel through ECCA, performs channel transmission if necessary, and then transmits an index of an OFDM symbol that starts transmission of a Tx data / control signal to a subframe boundary (k OFDM Only the PDCCH / PHICH (including the CRS), which is the control channel, can be transmitted without the same data transmission as the PDSCH when the number of symbols (#k) is 1 = <# k OFDM symbol = <specific threshold value (eg 3).

This is because only PDCCH / PHICH transmission is allowed because it is not efficient to transmit both PDCCH and PDSCH (EPDCCH) using a small number of OFDM symbols. Here, since the CRS transmission for the corresponding PDCCH demodulation may not exist in the corresponding OFDM symbol, a channel occupancy signal may be used for demodulation thereof, or the position of the CRS RE may be shifted on the time axis and allocated. It is also possible to use the CRS on the immediately following subframe as an artifact.

In addition, in the case of FIG. 20C, the corresponding PDCCH transmission in the partial sub-frame 2020 may be used to indicate PDSCH data scheduling on the next normal sub-frame 2030. In this case, there is no control channel transmission region on the next regular sub-frame 2030, and one sub-frame can be used purely for PDSCH data transmission. That is, the next regular sub-frame 2030 may include only the PDSCH region without the PDCCH region.

On the other hand, if the number of OFDM symbols k in the interval between the same subframe boundary and the index of the OFDM symbol that starts transmission of the Tx data / control signal in the partial subframe 2040 is less than a threshold value ), All physical layer data / control channels can be transmitted without such constraints.

The threshold can be determined automatically by default (see Tables 8, 9, 10, 11) by the candidate symbol index value. However, other considerations can be fixed through a CFI (Control Format Indicator) value for SCell set to a specific number (e.g., 3) or on the license-exempt band.

20E, one OFDM symbol index value (i.e., a maximum OFDM symbol index) is determined according to a maximum channel occupancy time and a time point at which the transmission should be terminated in the candidate symbol positions determined in the partial subframe 2070 (assuming three candidate OFDM symbol indexes) Can be selected. The method of selecting one OFDM symbol index value for determining the end point is to select the nearest candidate OFDM symbol index value just before the maximum channel occupancy time, thereby maximizing the frequency efficiency for data / control channel transmission There are advantages. (K) of OFDM symbols in the interval between the selected candidate OFDM symbol index and the boundary of the same subframe (partial subframe) where the selected candidate OFDM symbol index is located is smaller than a specific threshold value (e.g., 3) Only the PDCCH / PHICH (including the CRS) is transmitted. However, in the case where an interval smaller than one is shown, the transmission of the above channel is not considered.

21 is a flowchart showing an LAA communication operation by the base station according to the present invention.

Referring to FIG. 21, the BS selects an LAA frame structure for a cell using a license-exempt carrier wave (S2100). The base station includes one of a plurality of LAA frame structures having a predefined fixed frame period based on a propagation environment, distribution of surrounding cells, APs, STAs / terminals, cell load, Lt; RTI ID = 0.0 &gt; LAA &lt; / RTI &gt; Here, the plurality of LAA frame structures may have different frame periods, and the frame period may have a length of, for example, 1 ms to 10 ms. If it is predefined to use only one LAA frame structure, S2100 may be omitted.

The LAA frame structure may have a frame structure according to the methods 1 to 3 described above.

The base station transmits the LAA configuration information to the mobile station through the PCcell using the license carrier (S2110). The LAA configuration information may be transmitted to the LAA terminal via, for example, an RRC message. Where the RRC message may be, for example, an RRC connection reconfiguration message. The LAA configuration information includes relevant settings and parameters for LAA configuration. The LAA configuration information may specifically include information such as CCA (or CS) time, CCA timing configuration information, CCA threshold information. The CCA timing configuration information may include a CCA period and an offset.

In addition, the LAA configuration information may further include LAA RS measurement timing configuration information in a cell using the license-exempt carrier wave. The LAA RS measurement timing configuration information includes information about the timing associated with the LAA RS in the cell using the license-exempt carrier wave. On the other hand, if a specific LAA frame structure is selected in the S2100 procedure, an LAA frame structure index indicating the selected frame structure may be included in the LAA configuration information.

The base station performs CCA (or CS) on the license-exempt cell (S2120). The base station can determine whether the serving cell is channel interference or channel occupation based on the CCA. That is, the base station can determine whether the frame on the serving cell is busy or idle based on the CCA. The base station performs CCA based on CCA time, CCA timing configuration information, and CCA threshold information, determines that the frame associated with the CCA is busy if the detected energy is greater than a threshold value, And determines that the associated frame is in an idle state if the frame is smaller than the threshold value. If the associated frame is in an idle state, the base station may initiate occupancy of the associated frame.

In step S2130, the base station performs a channel reservation procedure to notify neighbor nodes (e.g., other base stations or terminals) that the base station occupies the frame when it is determined that the CCA results in an idle state.

For example, the base station transmits channel reservation information through a preamble signal transmission defined on a cell using a license-exempt carrier so that adjacent nodes can recognize that the frame occupies the frame. In this case, the preamble signal may be transmitted in the COT of the cell using the corresponding license-exempted carrier and / or after the CCA is performed, in a state that the cell using the corresponding license-exempted carrier is idle. The preamble signal may support a plurality of transmission nodes to support multiplexing using a code / frequency / time domain.

The preamble signal may include or indicate at least one of an LAA frame structure index, SCell enable / disable information using a license-exempt carrier, a time occupied for data transmission, UL grant information for CSI reporting, and a cell ID.

In another example, the base station instructs the terminal to reserve a channel for data transmission through dynamic small cell on / off signaling, and the terminal transmits a preamble (or beacon) signal including channel reservation information to a neighboring node using a license- Lt; / RTI &gt; Accordingly, adjacent nodes can recognize channel reservation information of a base station serving as a transmitting node, and unnecessary CCA can be performed and interference due to transmission can be prevented. The small cell on / off signaling and preamble signal may include or indicate at least one of an LAA frame structure index, a time occupied for data transmission, and a cell ID.

In operation 2130, when the base station is operating as an LBE-based LBT, the base station performs an LBT (when the channel is in a dormant state or a busy state and confirms a dormant state) After transmitting the channel occupancy signal to occupy the channel (if necessary), the OFDM symbol indexes determined according to the number of candidate OFDM symbol indexes and the number of the respective candidate OFDM symbol indexes to transmit the Tx data / , The OFDM symbol for the start point or the end point of transmission of the Tx data / control signal is determined.

This can be determined by taking Tables 8, 9, 10, and 11 as examples.

For example, an OFDM symbol index indicating the start point of the TX data / control signal may be determined according to the end of the LBT and depending on whether the channel occupancy signal is transmitted or not, while the time occupied by the base station is terminated The candidate OFDM symbol index immediately before the TX data / transmission signal can be determined as the end point of the TX data / transmission signal.

Only a specific LTE physical channel (e.g., PDCCH) may be transmitted according to an OFDM symbol index for the determined start and end points of the Tx data / control signal transmission, and in such case, cross subframe data scheduling is possible. Here, the cross subframe data scheduling refers to a scheduling method in which PDCCH transmission, which is a control channel for directing scheduling, and PDSCH transmission, which performs data transmission, occur in different subframes.

After completing the channel reservation procedure, the BS receives the CSI report from the MS (S2140). The base station can provide scheduling suitable for the channel environment to the UE based on the CSI report. In addition, it is based on the fact that the mobile station continuously performs operations necessary for transmission and reception on the license-exempt band, such as RRM, synchronization, and AGC (Automatic Gain Control).

The base station performs data transmission during a reserved interval of the cell using the license-exempt carrier wave (S2150). The base station transmits a PDCCH / EPDCCH (Enahcned PDCCH) through a cell (for example, PCell or SCell) using the license carrier and performs data transmission on the cell using the license-exempt carrier wave. The UE can receive data on the cell using the license-exempt carrier based on the PDCCH / EPDCCH.

22 is a flowchart showing an LAA communication operation by the terminal according to the present invention.

Referring to FIG. 22, the UE receives LAA configuration information from a base station via PCell using a license carrier (S2200). The LAA configuration information includes relevant settings and parameters for LAA configuration. The LAA configuration information may specifically include information such as CCA (or CS) time, CCA timing configuration information, CCA threshold information. The CCA timing configuration information may include a CCA period and an offset. The LAA configuration information may further include LAA RS measurement timing configuration information in a cell using the license-exempt carrier wave. The LAA RS measurement timing configuration information includes information about the timing associated with the LAA RS in the cell using the license-exempt carrier wave. The LAA configuration information may include an LAA frame structure index (LAA frame structure index).

The LAA frame structure of the cell using the license-exempt carrier wave may have a frame structure according to the methods 1 to 3 described above.

The UE performs channel measurement in the cell using the license-exempt carrier wave based on the LAA configuration information received from the base station (S2210). The UE can perform RRM / CSI / interference measurement and synchronization in the cell using the license-exempt carrier wave. This operation may be performed by the UE according to the channel period occupied by the BS and the indication information therefrom. The LAA terminal may transmit a measurement report containing measurement results to a base station via a cell (e. G., PCell) using a license carrier.

If the Node B determines that the Node B is in the idle state as a result of the CCA, the UE performs a channel reservation procedure with the Node B (S2220)

For example, the terminal may receive a preamble signal notifying the channel reservation from the base station. The preamble signal may include or indicate at least one of an LAA frame structure index, SCell enable / disable information using a license-exempt carrier, a time occupied for data transmission, UL grant information for CSI reporting, and a cell ID.

In another example, the terminal receives dynamic small cell on / off signaling from the base station, and the terminal may transmit a preamble (or beacon) signal including neighbor channel reservation information on a cell using the license-exempt carrier.

According to another embodiment of the present invention, in step 2220, the UE receives a channel occupancy signal transmitted for the purpose of occupying a channel according to the result of the LBE-based LBT performed by the base station. After receiving the channel occupancy signal, an OFDM symbol for a start point or an end point is calculated by considering an OFDM symbol index determined according to the number of candidate OFDM symbol indexes and the number of candidate OFDM symbol indexes for receiving a Tx data / . This can be determined in consideration of Tables 8, 9, 10, and 11.

For example, an OFDM symbol index indicating a start point of reception of a TX data / control signal may be determined according to whether the LBT is terminated or not, depending on whether the channel occupancy signal is transmitted or not, A candidate OFDM symbol index immediately before the reception of the TX data / control signal can be determined as the end point of reception of the TX data / control signal. The UE can monitor only a specific LTE physical channel (eg PDCCH) according to an OFDM symbol index for the start and end points of reception of the determined Tx data / control signal. In this case, according to the cross subframe data scheduling, PDSCH reception is possible in the frame.

After completing the channel reservation procedure, the UE performs CSI reporting to the BS (S2230). The base station can provide scheduling suitable for the channel environment to the UE based on the CSI report.

The terminal performs data reception during a reserved interval of the cell using the license-exempt carrier wave (S2240). The terminal expects to receive data during the corresponding reserved interval on the cell using the license-exempt carrier wave. In order to receive the data, the UE receives a PDCCH / EPDCCH (Enahcned PDCCH) through a cell (for example, PCell or SCell) using a license carrier, and receives data on a cell using the license-exempt carrier based on the PDCCH / EPDCH Can be monitored.

23 is an example of a block diagram showing an LAA supporting base station and a terminal according to the present invention.

23, the base station 2300 includes a memory 2305, a processor 2310, and a radio frequency unit (RF) unit 2320. The memory 2305 is coupled to the processor 2310 and stores various information for driving the processor 2310. [ RF section 2320 is coupled to processor 2310 and transmits and / or receives radio signals. Processor 2310 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 2310. [

The processor 2310 includes an LAA configuration unit 2311, a CCA processing unit 2312, and a scheduling unit 2313.

The LAA configuration unit 2311 generates LAA configuration information. The LAA configuration information includes relevant settings and parameters for LAA configuration. The LAA configuration information may specifically include information such as CCA (or CS) time, CCA timing configuration information, CCA threshold information. The CCA timing configuration information may include a CCA period and an offset. The LAA configuration information may further include LAA RS measurement timing configuration information in a cell using the license-exempt carrier wave. The LAA RS measurement timing configuration information includes information about the timing associated with the LAA RS in the cell using the license-exempt carrier wave. The LAA frame structure of the cell using the license-exempt carrier wave may have a frame structure according to the methods 1 to 3 described above.

The LAA configuration unit 2311 can select the LAA frame structure for the cell using the license-exempt carrier wave. In this case, the LAA configuration unit 2311 may generate the LAA configuration information further including an LAA frame structure index indicating the selected frame structure.

The LAA configuring unit 2311 transmits the generated LAA configuration information to a terminal 2350 through a RF unit 2305 on a cell (e.g., PCell or SCell) using a license carrier.

The CCA processing unit 2312 performs CCA (or CS) for the cell using the license-exempt carrier wave. The CCA processing unit 2312 can determine whether a specific frame or interval on the cell using the license-exempt carrier is busy or idle based on the CCA. The CCA processing unit 2312 performs CCA based on CCA time, CCA timing configuration information, and CCA threshold information, and determines that the frame associated with the CCA is in a busy state when the detected energy is greater than a threshold value, And may determine that the associated frame is in an idle state if the detected energy is less than a threshold value. If the CCA is determined to be in the idle state, the CCA processing unit 2312 performs the channel reservation procedure.

For example, the CCA processing unit 2312 generates a preamble signal so that neighboring nodes can recognize that the base station 2300 occupies a specific frame or section of the cell using the license-exempt carrier wave, and transmits the preamble signal through the RF unit 2320 And transmits the preamble signal. The RF unit 2320 can transmit the preamble signal on a cell using a license-exempt carrier wave. The preamble signal may include or indicate at least one of an LAA frame structure index, license-exempt SCell activation / deactivation information, time occupied for data transmission, UL grant information for CSI reporting, and cell ID.

As another example, the CCA processing unit 2312 generates a small cell on / off signaling and transmits the small cell on / off signaling to the terminal 2350 through the RF unit 2320. RF section 2320 may transmit the small cell on / off signaling to a terminal 2350 on a cell (e.g., PCell or SCell) using a license carrier.

The scheduling unit 2313 can transmit data to the terminal 2350 through the RF unit 2320 on the reserved specific frame or period of the cell using the license-exempt carrier wave.

The scheduling unit 2313 transmits the PDCCH / EPDCCH for instructing the data transmission on the cell using the license carrier through the RF unit 2320, and transmits the PDCCH / EPDCCH on the reserved specific frame or interval on the cell using the license- And transmits the data. The PDCCH / EPDCCH may include a DL grant. The scheduling unit 2313 can control to transmit the data on the PDCCH or the resource region of the cell using the license-exempt carrier indicated by the EPDCCH.

According to another embodiment of the present invention, when the base station scheduler 2313 operates as an LBE-based LBT, the base station scheduler 2313 performs an LBT (if the channel is in the idle state or the busy state and confirms the idle state) After transmitting the channel occupancy signal to occupy the channel (if necessary), the OFDM symbol indexes determined according to the number of candidate OFDM symbol indexes and the number of the respective candidate OFDM symbol indexes to transmit the Tx data / , The OFDM symbol for the Tx data / control signal transmission start point or end point can be determined. The OFDM symbol may be determined in consideration of Tables 8, 9, 10, and 11, for example. That is, the OFDM symbol index indicating the start point of the TX data / control signal can be determined according to the end of the LBT and depending on whether the channel occupancy signal is transmitted or not, The candidate OFDM symbol index of the immediately preceding candidate can be determined as the end point of the TX data / transmission signal, and can be provided to the terminal. Whereby the transmission of the data can be controlled.

The RF unit 2320 receives the CSI report from the terminal 2350 on the cell using the license-exempt carrier wave. The scheduling unit 2313 can perform scheduling suitable for the channel environment to the terminal 2350 based on the CSI report.

The terminal 2350 includes a memory 2355, a processor 2360, and an RF section 2370. The memory 2355 is coupled to the processor 2360 and stores various information for driving the processor 2360. RF section 2370 is coupled to processor 2360 to transmit and / or receive wireless signals. Processor 2360 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 implemented by the control of the processor 2360. [

The RF unit 2370 receives the LAA configuration information, the PDCCH / EPDCCH, and the small cell on / off signaling on a cell using a license carrier.

The processor 2360 includes an LAA configuration unit 2361, a channel measurement unit 2362, a channel reservation processing unit 2363, and a data processing unit 2364.

The LAA configuring unit 2361 configures related parameters for the cell using the license-exempt carrier wave at the terminal end based on the LAA configuration information. The relevant parameter may be an RRC related parameter.

The channel measurement unit 2362 performs channel measurement on the cell using the unreally chargeable carrier wave. The channel measurement unit 2362 may perform RRM / CSI / interference measurement and synchronization in the cell using the license-exempt carrier wave. The channel measurement unit 2362 can transmit the CSI report to the base station 2300 through the RF unit 2370 on the cell using the license-exempt carrier wave.

The channel reservation processing unit 2363 performs a channel reservation procedure when the base station 2300 determines that the CCA results in an idle state.

For example, the channel reservation processing unit 2363 can receive the preamble signal indicating the channel reservation from the base station 2300 on the cell using the license-exempt carrier wave through the RF unit 2370.

In another example, the channel reservation processing unit 2363 receives the small cell on / off signaling from the base station, and the channel reservation processing unit 2363 includes channel reservation information for neighboring nodes based on the small cell on / off signaling The preamble (or beacon) signal can be transmitted through the RF unit 2370 on the cell using the license-exempt carrier wave.

According to another embodiment of the present invention, the channel reservation processing unit 2363 of the terminal receives the channel occupancy signal transmitted for the purpose of occupying the channel according to the result of the LBE-based LBT performed in the base station. After receiving the channel occupancy signal, an OFDM symbol for a start point or an end point is calculated by considering an OFDM symbol index determined according to the number of candidate OFDM symbol indexes and the number of candidate OFDM symbol indexes for receiving a Tx data / You can decide. This can be determined in consideration of Tables 8, 9, 10, and 11.

For example, an OFDM symbol index indicating a start point of reception of a TX data / control signal may be determined according to whether the LBT is terminated or not, depending on whether the channel occupancy signal is transmitted or not, A candidate OFDM symbol index immediately before the reception of the TX data / control signal can be determined as the end point of reception of the TX data / control signal. The UE can monitor only a specific LTE physical channel (eg PDCCH) according to an OFDM symbol index for the start and end points of reception of the determined Tx data / control signal. In this case, according to the cross subframe data scheduling, PDSCH reception is possible in the frame.

The data processing unit 2364 performs data reception through the RF unit 2370 in a reserved specific frame or interval of the cell using the license-exempt carrier wave. The data processor 2364 can monitor the data reception through the RF unit 2370 in the subcarrier and time domain on the cell using the license-exempt carrier wave specified based on the received PDCCH / EPDCCH.

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.

In the above-described exemplary system, the methods are described on the basis of a flowchart as a series of steps or blocks, but the present invention is not limited to the order of the steps, and some steps may occur in different orders . It will also be understood by those skilled in the art that the steps shown in the flowchart are not exclusive and that other steps may be included or that one or more steps in the flowchart may be deleted without affecting the scope of the invention.

Claims (2)

A method of performing communication by a base station in a wireless communication system supporting LAA (Licensed Assisted Access)
Generating LAA configuration information for a cell using a license-exempt carrier wave;
Transmitting the generated LAA configuration information to a terminal on a cell using a license carrier;
Performing a clear channel assessment (CCA) on a cell using the unlicensed carrier wave;
Transmitting channel reservation information indicating to occupy a specific frame or interval on a cell using the license-exempt carrier to the terminal or neighboring nodes when it is determined that the CCA results in an idle state;
Transmitting a Physical Downlink Control Channel (PDCCH) or Enhanced PDCCH (Enhanced PDCCH) to a UE on a cell using the license carrier; And
And transmitting data on a resource region of a cell using the PDCCH or the license-exempt carrier indicated by the EPDCCH,
The LAA configuration information includes at least one of a CCA time, CCA timing configuration information, CCA threshold information, LAA RS measurement timing configuration information in a cell using the license-exempt carrier wave, and an LAA frame structure index Including,
Wherein the resource area is located within the specific frame or interval. A method for performing communication by a terminal in a wireless communication system supporting LAA (Licensed Assisted Access)
Receiving LAA configuration information for a cell using a license-exempt carrier using a license-exempt carrier from a base station on a cell using a license carrier;
Performing a configuration for a cell using the license-exempt carrier based on the received LAA configuration information;
Receiving channel reservation information from the base station on a cell using the license carrier, the channel reservation information indicating to occupy a specific frame or section of a cell using the license-exempt carrier;
Receiving a physical downlink control channel (PDCCH) or enhanced PDCCH (enhanced PDCCH) from a base station on a cell using the license carrier; And
Receiving data on a resource region of a cell using the PDCCH or the license-exempt carrier indicated by the EPDCCH,
The LAA configuration information includes at least one of a CCA time, CCA timing configuration information, CCA threshold information, LAA RS measurement timing configuration information in a cell using the license-exempt carrier wave, and an LAA frame structure index Including,
Wherein the resource area is located within the specific frame or interval.

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