KR20160094234A - Method and apparatus of performing csi report for serving cell on unlicensed band in wireless communication system - Google Patents

Abstract

The present invention relates to a method for periodically reporting channel state information (CSI) by a terminal in a license assisted access (LAA)-based wireless communication system which supports carrier aggregation between a serving cell in a licensed band and a serving cell in an unlicensed band. The method comprises the steps of: determining whether a collision between a plurality of periodic CSI reports occurs on sub-frame n; determining whether periodic CSI reports for a serving cell in an unlicensed band, among the plurality of periodic CSI reports, are valid when a collision between the plurality of periodic CSI reports occurs; selecting, on the basis of the priority, one periodic CSI report from among the plurality of periodic CSI reports excluding invalid periodic CSI reports for the serving cell in the unlicensed band; and transmitting the selected one periodic CSI report to a base station.

Description

TECHNICAL FIELD The present invention relates to a method and apparatus for performing CSI reporting for a serving cell in a license-exempt band in a wireless communication system,

The present invention relates to wireless communication, and more particularly, to a method and apparatus for performing a CSI (Channel State Information) report for a serving cell in a license-exempt band in a wireless communication system.

The wireless communication system adjusts the modulation and coding scheme (MCS) and the transmission power according to a given channel, using link adaptation in order to make full use of a given channel capacity. Here, the link adaptation means changing the modulation and channel coding scheme according to the situation of the radio link to achieve optimal communication performance. To perform such link adaptation at the base station, periodic feedback of the channel state information of the UE is required. To this end, the UE performs CSI reporting.

Meanwhile, as wireless communication traffic increases, small cells such as a pico cell, a femtocell, a micro cell, a remote radio head (RRH) ), Relays, and repeaters are actively used, 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 be different from the radio frame structure in the license band.

Therefore, wireless communication technology considering support / management / operation of licensed band communication technique for smoothly supporting wireless communication in the license-exempted band is required, and a method of reporting channel state information (CSI) for a license- It is true.

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

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

Another aspect of the present invention is to provide a cyclic CSI reporting method and apparatus in a wireless communication system.

According to an aspect of the present invention, there is provided a method of transmitting a CSI (Cyclic Redundancy Check) of a terminal in a license assisted access (LAA) based wireless communication system supporting carrier aggregation between a serving cell in a licensed band and a serving cell in an unlicensed band (Channel State Information) reporting method. The method includes determining whether a plurality of periodic CSI reports on a subframe n collide with each other, if the plurality of periodic CSI reports are in conflict, determining a periodic CSI report for a serving cell of an unlicensed band among the plurality of periodic CSI reports Selecting one periodic CSI report based on the priority among the remaining periodic CSI reports excluding the periodic CSI reports for the serving cell of the unlicensed band in which the plurality of periodic CSI reports are invalid; And transmitting the selected one periodic CSI report to the base station.

According to another aspect of the present invention, a cyclic CSI report is provided in a licensed assisted access (LAA) based wireless communication system that supports carrier aggregation between a licensed band serving cell and an unlicensed band serving cell. And provides a terminal to perform. The UE determines whether a plurality of periodic CSI reports collide with each other in a subframe n, and if the plurality of periodic CSI reports are in conflict, whether the periodic CSI report for the serving cell of the license- And selecting one periodic CSI report based on the priority among the remaining periodic CSI reports excluding the periodic CSI reports for the serving cell of the unlicensed band in which the plurality of periodic CSI reports are invalid, And a radio frequency unit for transmitting the periodic CSI report of the base station to the base station.

According to another aspect of the present invention, in a LAA (License Assisted Access) based wireless communication system supporting carrier aggregation between a serving cell in a licensed band and a serving cell in an unlicensed band, And provides a CSI (Channel State Information) report processing method. The method includes performing an RRC connection reconfiguration procedure for configuring a carrier wave of the license band and a carrier wave of the license-exempt band as serving cells, and when a plurality of periodic CSI reports collide on the subframe n, Receiving a periodic CSI report selected by the UE based on the validity and priority of the periodic CSI report for the cell, and performing scheduling for the UE based on the periodic CSI report .

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.

In addition, according to the present invention, a UE can efficiently perform CSI reporting on a serving cell in a license-exempt band, and a base station can perform modulation and channel coding So as to achieve optimum communication performance.

1 shows a wireless communication system to which the present invention is applied.
Figure 2 shows examples of LAA deployment scenarios to which the present invention is applied.
Figure 3 shows an example of timing for an FBE according to the present invention.
FIG. 4 shows an example in which a CA is configured between a serving cell in a license band and a serving cell in an unlicensed band, and a periodic CSI report is collided.
5 shows an example of a case where valid periodic CSI reporting is collided.
6 illustrates a method of performing a periodic CSI report according to an embodiment of the present invention.
FIG. 7 illustrates a method of performing a cyclic CSI report according to another embodiment of the present invention.
8 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 shows a wireless communication system to which the present invention is applied.

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

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

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

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

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

On the other hand, since a small cell generally serves a small area compared to a macro cell, it is advantageous over a macro cell in terms of throughput that can be provided for a single terminal. As the wireless communication traffic surges, the small cell as described above is positively utilized, but it is becoming an urgent problem to secure more frequencies in order to improve the performance.

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

In the present invention, the term LAA (License Assisted Access) refers to a case where one or more SCs operating in a license-exempt band or an unlicensed spectrum based on Assisted PCell operating in a license band or a spectrum, It is a wireless communication technique that supports operation. In a LAA deployment scenario, the configured SCell on the license-exempt zone may be located within macro coverage or may be located outside of macro coverage. In addition, the configured SCell on the license-exempt zone may be located in an indoor location, such as a typical home or a particular complex, or may be located 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 may refer to a backhaul having a delay of 2.5 .mu.s or less and a capacity of 10 Gbps or more. The criteria for this may vary depending on the communication environment, the wireless communication protocol, and the like.

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

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

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

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

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

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

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

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

The channel access mechanism according to the present invention provides opportunistic channel access. A CCA (Clear Channel Assessment) is applied before the wireless communication device uses the channel for the opportunistic channel connection. This is to avoid concurrent transmissions on the same channel as other Radio Local Area Network (RLAN) systems. Here, the CCA indicates a procedure for determining whether the corresponding channel is a channel interference or a channel occupied state, that is, whether the corresponding channel is busy or idle, through energy scan or detection for the corresponding channel. The CCA can be performed based on whether or not energy is detected during a certain monitoring time. Here, the EIRP (equivalent isotropic radio power) obtained through the energy detection is compared with the predefined CCA threshold value to determine whether the corresponding channel is busy or idle. The CCA check can be performed based on "energy detection" during a CCA monitoring time of more than 20 microseconds. The channel access mechanism according to the present invention based on the carrier sense (CS) as described above may be called LBT (Listen Before Talk).

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

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

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

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

Referring to FIG. 3, the CCA performed in the FBE and the resources obtainable through the CCA are defined as a frame structure. The FBE includes an idle period and a channel occupancy time within one frame period. Where the idle period may be at least 5% of the channel occupancy time. The idle period also includes the CCA (monitoring) time. Here, the CCA time may be, for example, 20 μs or more. In the FBE, the CCA is performed once within a frame.

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

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

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

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

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

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

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

On the other hand, in order to control the base station to change the modulation and channel coding scheme according to the situation of the radio link to achieve the optimal communication performance, periodic feedback of the channel state information of the UE is required. The CSI report can be performed through a Physical Uplink Control Channel (PUCCH) carrying uplink control information. Or a Physical Uplink Shared Channel (PUSCH) is transmitted, the CSI report may be performed through the PUSCH.

The CSI report can be periodically performed in accordance with the period set in the upper layer. Such a CSI report may be referred to as periodic CSI reporting. The terminal may be set semi-statically by an upper layer signal to periodically feed back different CSI type elements (CQI, PMI, RI, PTI) via the PUCCH.

The CQI (Channel Quality Indicator) provides information on link adaptive parameters that the UE can support for a given time. The CQI may indicate a data rate that can be supported by the downlink channel in consideration of the characteristics of the terminal receiver and the signal to interference plus noise ratio (SINR). The base station can determine the modulation (QPSK, 16-QAM, 64-QAM, etc.) to be applied to the downlink channel and the coding rate using the CQI. The CQI can be generated in several ways. For example, a channel state can be directly quantized and fed back, a signal-to-interference plus noise ratio (SINR) can be calculated and fed back, and a MCS (Modulation Coding Scheme) have. When the CQI is generated based on the MCS, the MCS includes a modulation scheme, a coding scheme, and a coding rate according to the modulation scheme, the coding scheme, and the like.

A precoding matrix index (PMI) provides information on a precoding matrix in precoding based on a codebook. PMI is associated with multiple input multiple output (MIMO). The feedback of PMI in MIMO is called closed loop MIMO (MIMO).

A rank indication (RI) is information on a rank (i.e., the number of layers) recommended by the UE. That is, RI represents the number of independent streams used for spatial multiplexing. The RI is fed back only when the terminal operates in the MIMO mode using spatial multiplexing. RI is always associated with one or more CQI feedback. That is, the feedback CQI is calculated assuming a specific RI value. Since the rank of the channel generally changes slower than the CQI, the RI is fed back a number of times less than the CQI. The RI transmission period may be a multiple of the CQI / PMI transmission period.

When a CA is configured in the terminal, periodic CSI reporting is performed for only one serving cell in one time instance. That is, periodic CSI reporting can be performed with different periods and offsets for each serving cell independently of each other. In this case, periodic CSI reporting for a plurality of serving cells may be performed in one time instance (i.e., (I.e., collision) on a frame-by-frame basis. In this case, the CSI report for one serving cell can be performed based on the priority.

For example, the priority may be set as shown in the following table.

Priority Type First CSI reporting type 3,5,6,2a - RI, wideband 'first' Precoding Matrix Indicator Second CSI reporting type 2,2b, 2c, 4 - other Wideband CQI and / or PMI reports Third CSI reporting type 1, 1a - sub-band CQI / PMI reports Fourth Lowest Serving Cell index

If the periodic CSI reports for different serving cells collide on the same time instance as shown in Table 2, a periodic CSI report having a high priority is performed based on the priority determined according to the CSI report type or the like. On the other hand, according to the fourth priority, when the colliding periodic CSI reports have the same priority in the first to third priorities, the cyclic CSI reports for the serving cell having the relatively lowest serving cell index CSI reporting is performed. That is, according to the priority order, the periodic CSI report of some serving cells is dropped, the periodic CSI report for one serving cell is delivered to the base station through PUCCH (or PUSCH if PUSCH transmission is set) The base station may use the periodic CSI report for DL scheduling. The PUCCH may be transmitted on the SCell where the transmission of the PCell or PUCCH is established.

Table 3 below describes the CSI reporting type for Table 2 below.

Type 1 report supports CQI feedback for the UE selected sub-bands Type 1a report supports subband CQI and second PMI feedback Type 2, Type 2b, and Type 2c report supports wideband CQI and PMI feedback Type 2a report supports wideband PMI feedback Type 3 report supports RI feedback Type 4 report supports wideband CQI Type 5 report supports RI and wideband PMI feedback Type 6 report supports RI and PTI feedback

On the other hand, in the LAA scenario, the UL / DL transmission / reception of SCells configured on the license-exempt band is possible after the channel is acquired by performing the LBT. That is, UL / DL transmission / reception is possible after acquiring (or occupying) the frequency and time on the SCell in the license-exempt band based on the LBT. CSI reporting is generally performed for activated CCs. On the other hand, in the LAA-based communication, considering the carrier selection of the base station and the LBT implementation, the following two configurations of the UE can be considered.

- Alt 1. Configuration of the serving cell (s) in the license-exempt band (by RRC layer) => Activation of the configured serving cell (s) by MAC (Media Access Control) layer => LBT (on / off) . Here, LBT on indicates that the channel is acquired, and off indicates that the channel is not acquired.

- Alt 2. Configuration of the serving cell (s) in the license-exempt band (by RRC layer) => Channel acquisition based on LBT (on / off)

The difference between the above-described Alt 1 and Alt 2 is whether or not activation signaling in the MAC layer for the constructed serving cell (s) in the license-exempt band is considered for power saving of the UE or the like. The periodic CSI reporting method according to the present invention can be performed on a serving cell for which CSI reporting is required based on the result of LBT regardless of the setting state of the UE.

FIG. 4 shows an example in which a CA is configured between a serving cell in a license band and a serving cell in an unlicensed band, and a periodic CSI report is collided. FIG. 4 shows that PCell, SCell # 1 and SCell # 2 are CA-configured in the terminal, PCell uses the license band frequency f1, SCell # 1 uses the frequency f2 of the license-exempt band and SCell # f3 is used.

Referring to FIG. 4, a hole is a timing (subframe) at which periodic CSI reporting should be performed. As can be seen in FIG. 4, the timing of periodic CSI reporting for PCell and the timing of periodic CSI reporting for SCell # 1 may conflict (400), or the timing of periodic CSI reporting for PCell, SCell # 1 The timing of periodic CSI reporting for SCell # 2 may conflict with the timing of periodic CSI reporting for SCell # 2 (410).

Here, in the LAA environment, the channel acquisition operation is performed through the LBT for the SCell in the license-exempt band, and UL / DL transmission / reception is possible only in the SCell # 1 and SCell # 2 when the radio resource is occupied . Therefore, in consideration of the collision of the cyclic CSI report in the LAA environment, not only cyclic CSI reporting related parameters set through semi-static RRC signaling but also on / off of SCell of the corresponding license- ).

The base station transmits a CQI / PMI periodic report with semi-static RRC signaling to the cqi-pmi-ConfigIndex (I _{CQI / PMI} ) value for each serving cell (TM1-9 case) or each CSI process And sets the period N _pd , the offset N _{OFFSET, and RI} (in subframe units) to the UE. Also, RI similarly sets the period M _RI of the RI report and the relative offset N _{OFFSET, RI} value to the UE through the semi-static RRC signaling ri-ConfigIndex (I _RI ). Therefore, the timing for CQI / PMI and periodic reporting of RI is determined by using the above RRC signaling and the corresponding period value and offset value table. Tables 4 and 5 below show examples of tables for determining the reporting period of the CQI / PMI and RI corresponding to the RRC parameter transmitted from the base station to the terminal.

Referring to Table 4, N _pd and N _OFFSET in the PCell frame structure type of FDD or FDD-TDD mode _{, and CQI} can be set as shown in the table according to I _{CQI / PMI} , , M _RI and N _{OFFSET, and RI} can be set according to the above table according to I _RI .

5 shows an example of a case where valid periodic CSI reporting is collided.

Referring to FIG. 5, a hole is a periodic CSI reporting timing (subframe) according to a CSI reporting related parameter, and a dot is a timing at which a substantially effective CSI reporting can be performed. As shown in FIG. 5, the timing of periodic CSI reporting for PCell and the timing of periodic CSI reporting for SCell # 1 may conflict with each other at the time of identification number 500, but the SCell # 1 of the license-exempt band may not acquire the channel A valid periodic CSI report can not be performed. That is, even if cyclic CSI reporting is performed in SCell # 1 without license acquisition in the license-exempted band, the out-of-range value or out-of-range value is displayed. Therefore, in this case, only the periodic CSI report for PCell is effectively performed.

On the other hand, at the time of the identification number 510, the timing of the periodic CSI report to PCell, the timing of the periodic CSI report to SCell # 1, and the timing of the periodic CSI report to SCell # 2 are in conflict and SCell # 1 and SCell In # 2, since the channel is acquired, a valid periodic CSI report can be performed.

Therefore, if there occurs a substantial collision between the periodic CSI report for the PCell, the periodic CSI report for SCell # 1, and the periodic CSI report for SCell # 2, and if the periodic CSI report for all the serving cells can not be performed, A UE to which cyclic CSI reporting is to be performed through a PUCCH can only report CSI for one serving cell, and a method for resolving the CSI report needs to be defined.

The present invention can provide a serving cell configured on a licensed carrier (L-carrier) and a delimiter for serving cells configured on a license-exempt carrier (U-carrier) for effective periodic CSI reporting. That is, an indicator indicating whether the corresponding SCell is configured on the U-carrier may be used in each SCell setting. The indicator may be an RRC-related parameter and may be indicated via an E-ARFCN (Evolved Absolute Radio Frequency Channel Number) value. That is, depending on whether the value of the E-ARFCN corresponds to the license-exempt carrier, it can be indicated whether the SCell set with the value is configured on the license carrier or on the license-exempt carrier.

The E-ARFCN value is added to the SCell setting information to set the CA.

If the LAA operation is set with the improved CA configuration in the UE and a plurality of periodic CSI timings are sent in subframe n (PUCCH transmission subframe), the serving cell (s) corresponding to the L-carrier is excluded (Determined as valid), and the subframe n of the serving cell among the serving cell (s) corresponding to the remaining U-carriers is a subframe (on) occupied (channel acquired) by the base station, (periodic) CSI report for the serving cell is valid if the previous subframes (including nk) nk were subframes (on) occupied by (k> 0) base stations.

That is, when at least one of the sub-frames (including nk) or sub-frame n preceding at least the sub-frame nk of the serving cell is occupied by the base station among the serving cells (s) set in the U- The (periodic) CSI report in That is, in this case, the CQI value included in the CSI report of the corresponding serving cell is not out-of-range.

Also, according to the present invention, periodic CSI reporting on a serving cell (PCell or SCell) on L-carrier and periodic CSI reporting on a serving cell (SCell) on U-carrier determined to be valid in the above Carrier may be referred to as an effective periodic CSI report for a serving cell on a U-carrier), the valid periodic CSI report for the serving cell on the U-carrier is higher than the periodic CSI report for the serving cell on the L-carrier (Or defined) to have priority. On the U-carrier, the channel access opportunity is more rarely provided than the L-carrier through carrier selection and LBT. Therefore, an opportunity for reliable CSI reporting is secured and the occupied subframes of the serving cell on the U- To maximize the use of resources on the Internet. This can have a negative impact on system performance if the CSI report of serving cells on U-carriers drops due to opportunistic transmission rather than dropping the CSI of the serving cell on the always-occupied L-carrier to be. Also, it may be incompatible with the LAA introduction motive for off-loading more data transmissions onto the u-carrier.

A method of performing periodic CSI reporting considering a license-deferred serving cell according to the present invention will be described in more detail as follows.

6 illustrates a method of performing a periodic CSI report according to an embodiment of the present invention.

Referring to FIG. 6, the UE confirms that transmissions of periodic CSI reports for a plurality of serving cells configured in the UE are generated in one uplink subframe (S600). That is, the UE determines whether a plurality of CSI reporting timings collide with each other in the subframe n.

If a collision occurs in S600, the UE extracts an effective periodic CSI report for the serving cell on the U-carrier (S610). In this case, if the subframe n of the serving cell is occupied (channel acquired) by the base station (on), the UE determines that the cyclic CSI report in the subframe n for the serving cell is valid .

As another example, if at least one subframe among the serving cells corresponding to U-carriers among the subframes nk (including nk, k> 0) of the serving cell is occupied by the base station, The periodic CSI report in subframe n for the serving cell may be determined to be valid. The value of k may be a value between a subframe corresponding to the CSI reporting timing of one week ago and a subframe corresponding to the CSI reporting timing of the current cycle. Thus, the value of k is less than or equal to the CSI reporting period value. For example, if a CSI report is performed with a 10-ms period, it is an arbitrary value between the subframe n-10 and the subframe n (e.g. 0 <k <= 10). If there is no valid periodic CSI report in step S610, the UE determines that it does not perform periodic CSI reports on the serving cells on the U-carriers, and performs periodic CSI reporting on serving cells on the L- The periodic CSI report for the last serving cell based on the rank is selected (S640). The priorities according to Table 2 apply to the priority among periodic CSI reports for serving cells on the L-carrier.

If there is a periodic CSI report (s) for the serving cell (s) on the L-carriers and there is an effective periodic CSI report (s) for the serving cell (s) on the U- the validity periodic CSI report (s) for the serving cell (s) on the carriers are prioritized (S620) over the periodic CSI report (s) for the serving cell (s) on the L-carriers. That is, the terminal drops the periodic CSI report (s) for the serving cell (s) on L-carriers.

Thereafter, when there are a plurality of serving cells (on U-carriers) having an effective periodic CSI report, the UE applies a priority according to the serving cell index for each CSI report type according to Table 2 between the plurality of serving cells (S630).

The UE selects one periodic CSI report based on the applied priority (S640). The UE may transmit the selected one periodic CSI report to the base station via the PUCCH (or PUSCH).

Meanwhile, if no collision occurs in S600, the UE can select and perform periodic CSI reporting on the currently generated one serving cell.

The priority rules between periodic CSI reports according to an exemplary embodiment of the present invention may be shown in Table 6, for example.

Priority Type First Carrier Type (U-carrier> L-carrier) Second CSI reporting type 3,5,6,2a - RI, wideband 'first' Precoding Matrix Indicator Third CSI reporting type 2,2b, 2c, 4 - other Wideband CQI and / or PMI reports Fourth CSI reporting type 1, 1a - sub-band CQI / PMI reports Fifth Lowest Serving Cell index

Referring to Table 6, it is determined whether the periodic CSI report is related to the serving cell set in the U-carrier or the serving cell set in the L-carrier in the first priority, CSI reporting has a higher priority. That is, if a periodic CSI report about a serving cell set in a U-carrier and a serving cell set in an L-carrier corresponding to a valid periodic CSI report collides in one subframe, The CSI report is dropped. Thereafter, the periodic CSI report having the higher priority is selected in the second, third, fourth, and so on until the last one periodic CSI report is left, and the periodic CSI report having the lower priority is dropped. If a plurality of periodic CSI reports still remain after the fourth priority, periodic CSI reporting for the serving cell with the lowest serving cell index based on the fifth priority is selected and performed.

That is, CSI reports for the SCs configured on the U-carrier are transmitted in the order of L (L), regardless of the CSI report type or the serving cell index of the corresponding SCell, lt; RTI ID = 0.0 &gt; (PCell / SCells) &lt; / RTI &gt; This configuration allows data to be offloaded from the L-carrier to the U-carrier to distribute the traffic of the L-carrier. Therefore, since more CSI information is required to perform more data transmission on the U-carrier, it can be given priority over the CSI corresponding to the L-carrier.

FIG. 7 illustrates a method of performing a cyclic CSI report according to another embodiment of the present invention.

Referring to FIG. 7, in step S700, the UE confirms collision of valid periodic CSI reports for a plurality of serving cells configured in the UE. That is, the UE determines whether a plurality of CSI reporting timings collide with each other in the subframe n.

If the collision occurs, the UE extracts an effective periodic CSI report for the serving cell on the U-carrier (S710). [0060] The UE determines whether the subframe n of the serving cell is occupied (channel acquired) In the case of the subframe (on), the periodic CSI report in the subframe n for the serving cell can be determined to be valid.

As another example, if at least one subframe among the serving cells corresponding to U-carriers among the subframes nk (including nk, k> 0) of the serving cell is occupied by the base station, The periodic CSI report in subframe n for the serving cell may be determined to be valid.

That is, the timing of the cyclic CSI report for the PCell and the timing of the CSI report of the SCell of the license-exempt band are overlapped with each other at the predetermined time, but since the channel is acquired in the SCell, it is judged as a valid periodic CSI report.

Meanwhile, if there is no valid periodic CSI report, the UE determines that it does not perform periodic CSI reports on serving cells on U-carriers, and determines priority among periodic CSI reports for serving cells on an L- Lt; RTI ID = 0.0 &gt; CSI &lt; / RTI &gt;

If there are a plurality of CSI reports remaining thereafter, the CSI reporting type based priority is applied (S720). For example, the UE can apply the priority based on the priority rules of the first to third of Table 2 above.

Here, if periodic CSI reports having the same priority exist, a priority based on the carrier type and / or the serving cell index is applied (S730). That is, if the terminal has a periodic CSI report (s) for the serving cell (s) on L-carriers and there is an effective periodic CSI report (s) for the serving cell (s) on U- (S) for the serving cell (s) on the U-carriers with a higher priority than the periodic CSI report (s) for the serving cell (s) on the L-carriers. That is, the terminal drops the periodic CSI report (s) for the serving cell (s) on L-carriers. If there is still periodic CSI reports having the same priority, the UE can apply the CSI report for the serving cell having the lowest serving cell index with a higher priority based on the serving cell index.

 Thereafter, the UE selects one periodic CSI report based on the applied priority (S740). The UE may transmit the selected one periodic CSI report to the base station via the PUCCH (or PUSCH).

On the other hand, if there is no collision in S700, the UE can select and perform the periodic CSI report for the currently generated one serving cell. If only one periodic CSI report is left as a result of the priority application in S720, Can be moved.

The priority rules between periodic CSI reports according to another embodiment of the present invention can be represented as shown in Table 7, for example.

Priority Type First CSI reporting type 3,5,6,2a - RI, wideband 'first' Precoding Matrix Indicator Second CSI reporting type 2,2b, 2c, 4 - other Wideband CQI and / or PMI reports Third CSI reporting type 1, 1a - sub-band CQI / PMI reports Fourth Carrier Type (U-carrier> L-carrier) Fifth Lowest Serving Cell index

Referring to Table 7, the priority is maintained based on the CSI report type. However, even if the third priority is reached, the cyclic CSI report on the U-carrier takes a higher priority The priority of the CSI measurement for opportunistic transmission is taken into consideration. If there is still a plurality of CSI reports remaining, the last one CSI report can be selected based on the serving cell index.

In addition, the priority rules among the periodic CSI reports according to another embodiment of the present invention can be expressed as shown in Table 8 below.

Priority Type First CSI reporting type 3,5,6,2a - RI, wideband 'first' Precoding Matrix Indicator Second Carrier Type (U-carrier> L-carrier) Third CSI reporting type 2,2b, 2c, 4 - other Wideband CQI and / or PMI reports Fourth CSI reporting type 1, 1a - sub-band CQI / PMI reports Fifth Lowest Serving Cell index

Referring to Table 8, the above-described another embodiment firstly considers the RI and the first wideband PMI information, which should be considered most important for DL scheduling, and then the carrier type . Even if the RI and the first broadband PMI information are not received, the rest of the CSI information may be received. However, the RI and the first wideband PMI information may be preferentially considered in order to prevent the scheduling.

In addition, the priority rules between periodic CSI reports according to another embodiment of the present invention can be expressed as shown in Table 9 below.

Priority Type First CSI reporting type 3,5,6,2a - RI, wideband 'first' Precoding Matrix Indicator Second CSI reporting type 2,2b, 2c, 4 - other Wideband CQI and / or PMI reports Third Carrier Type (U-carrier> L-carrier) Fourth CSI reporting type 1, 1a - sub-band CQI / PMI reports Fifth Lowest Serving Cell index

Referring to Table 9, the another embodiment firstly considers the RI and the first wideband PMI information that should be considered most important for DL scheduling, and then the other broadband CQI / PMI information And then considering the carrier type. If there is no first broadband PMI information or other broadband CQI / PMI information, the rest of the CSI information may be received after the RI and the first broadband PMI information or other broadband CQI / PMI information. In this case, Other broadband CQI / PMI information may be considered preferentially over carrier type information.

As described above, according to an exemplary embodiment of the present invention, periodic CSI reports for serving cells set in a U-carrier within a priority order based on the carrier type have higher priority than periodic CSI reports of L-carriers.

In another embodiment of the present invention, when priority is given to data transmission on a serving cell set in an L-carrier, a periodic CSI report for serving cells set in an L-carrier has a higher priority than a cyclic CSI report of a U- Lt; / RTI &gt;

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

8, a base station 800 includes a memory 805, a processor 810, and a radio frequency unit 820. The memory 805 is coupled to the processor 810 and stores various information for driving the processor 810. The RF unit 820 is connected to the processor 810 and transmits and / or receives radio signals. The processor 810 implements the proposed functions, procedures and / or methods for performing the operations according to the present invention. In the above-described embodiments, the operation of the base station can be implemented by control of the processor 810. [

The processor 810 includes a serving cell configuration unit 811, an activation processing unit 812, a CCA performing unit 813, and a PHY processing unit 814. [

The serving cell configuration unit 811 may generate an RRC connection reconfiguration message including the information for configuring the license carriers and the license-exempt carriers into serving cells in the UE, and may transmit the RRC connection reconfiguration message to the UE through the RF unit 820. [ The RRC connection reconfiguration message may be transmitted via a PCell using a license carrier. The RF unit 820 may receive an RRC connection reconfiguration complete message from the terminal 850.

The activation processing unit 812 generates an activation / deactivation indicator for the SCells configured in the terminal 850, and transmits the generated activation / deactivation indicator to the terminal through the RF unit 820. The activation / deactivation indicator may be included in the MAC message and transmitted to the terminal through the PCell.

The CCA performing unit 813 performs a channel acquisition procedure for SCelles in the activated license-exempt band. The channel acquisition procedure may be performed based on CCA. When the activation procedure for the SCell in the license-exempt band is omitted by the appointment between the terminal 850 and the base station 800, the CCA performing unit 813 determines whether the SCell in the license- May perform the channel acquisition procedure for the channel.

The CCA performing unit 813 may generate channel acquisition information for at least one SCell of the license-exempt band based on the channel acquisition procedure. The channel acquisition information may indicate the channel acquired SCell and the acquired (occupied) subframes for the SCell.

The PHY processor 814 may generate a preamble (or PDCCH) including the channel acquisition information and transmit the preamble (or PDCCH) to the UE through the RF unit 820.

The RF unit 820 may perform periodic CSI report reception on the SCell of the channel-obtained license-exempt band. The PHY processing unit 814 configures the semi-static RRC signaling to set a value for instructing periodic reporting of CQI / PMI and RI. The periodic value and the offset value can be set based on the cqi-pmi-ConfigIndex (I _{CQI / PMI} ) value for the periodic reporting of the _{CQI / PMI} , and the timing for the periodic reporting of the RI can be set to ri- ConfigIndex _RI ) value, it is possible to set the period value and the offset value. The period value and the offset value can be set, for example, by the table values in Tables 4 and 5. [

In addition, when a collision occurs in the periodic CSI reporting timing in the subframe n, the CSI processing unit 864 can finally select one periodic CSI report by applying the above-mentioned periodic CSI reporting priority. The CSI processing unit 864 may select any one of the periodic CSI reports of the collided periodic CSI reports based on, for example, the priority of at least one of Tables 2 and 6 to 9 described above. The CSI processing unit 864 may control the RF unit 870 to perform the selected periodic CSI reporting.

In addition, the PHY processing unit 863 can perform data transmission / reception with the base station 800 on the obtained (occupied) sub-frames of the SCell of the license-exempt band through the RF unit 870.

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

Claims (13)

(CSI) reporting method in a License Assisted Access (LAA) based wireless communication system supporting carrier aggregation between a licensed band serving cell and an unlicensed band serving cell As a result,
Determining if a plurality of periodic CSI reports collide on subframe n;
Determining whether a periodic CSI report for a serving cell of an unlicensed bandwidth is valid among the plurality of periodic CSI reports if the plurality of periodic CSI reports collide with each other;
Selecting one periodic CSI report based on priority among the remaining periodic CSI reports excluding the periodic CSI reports for the serving cell of the unlicensed band in which the plurality of periodic CSI reports are invalid; And
And transmitting the selected one periodic CSI report to a base station. The method according to claim 1,
Wherein the validity of the periodic CSI report for the serving cell in the license-exempt zone is determined based on whether the subframe n of the serving cell in the license-exempt zone is a channel-obtained subframe. The method according to claim 1,
The validity of the cyclic CSI report for the serving cell of the license-exempt band is determined based on whether at least one subframe among the subframe n-4 to subframe n of the serving cell of the license-exempt band is a channel-acquired subframe Lt; RTI ID = 0.0 &gt; CSI &lt; / RTI &gt; reporting method. The method according to claim 1,
Characterized in that the priority is based on the following table (T1)

(T1)
Periodic CSI reporting method. The method according to claim 1,
Characterized in that the priority is based on the following table (T2)

(T2)
Periodic CSI reporting method. The method according to claim 1,
Characterized in that the priority is based on the following table (T3)

(T3)
Periodic CSI reporting method. A terminal that performs periodic CSI reporting in a license assisted access (LAA) based wireless communication system that supports carrier aggregation between a serving cell in a licensed band and a serving cell in an unlicensed band,
Determining whether a plurality of periodic CSI reports collide with each other in a subframe n, determining whether the cyclic CSI report for the serving cell in the license-exempt band among the plurality of periodic CSI reports is valid if the plurality of periodic CSI reports collide A processor for selecting one periodic CSI report based on the priority among the remaining periodic CSI reports excluding the periodic CSI reports for the serving cell of the unlicensed band in which the plurality of periodic CSI reports are invalid; And
And a radio frequency unit for transmitting the selected one periodic CSI report to a base station. 8. The method of claim 7,
Wherein the processor determines whether the periodic CSI report for the serving cell of the license-exempted band is valid based on whether the subframe n of the serving cell of the license-exempt band is a channel-obtained subframe. 8. The method of claim 7,
The processor determines whether the periodic CSI report for the serving cell of the license-exempted band is valid by checking whether at least one of the subframes n-4 to n of the serving cell of the license-exempt band is a channel-acquired subframe Based on the received information. 8. The method of claim 7,
Characterized in that the processor determines the priority based on the following table (T4)

(T4)
Terminal. 8. The method of claim 7,
Wherein the processor determines the priority based on the following table (T5). &Lt; RTI ID = 0.0 &gt;

(T5)
Terminal. 8. The method of claim 7,
Wherein the processor determines the priority based on the following table (T6): &lt; RTI ID = 0.0 &gt;

(T6)
Terminal. (CSI) report processing method of a base station in a License Assisted Access (LAA) based wireless communication system supporting carrier aggregation between a licensed band serving cell and an unlicensed band serving cell In this case,
Performing an RRC connection reconfiguration procedure for configuring a carrier wave of the license band and a carrier wave of the license-exempt band as serving cells;
Receiving a periodic CSI report selected by the terminal based on the validity and priority of the periodic CSI report for a serving cell of an unlicensed band when a plurality of periodic CSI reports collide on the subframe n; And
And performing scheduling for the UE based on the periodic CSI report.

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