WO2016122109A1

WO2016122109A1 - Method and apparatus for performing csi reporting for serving cell in unlicensed band in wireless communication system

Info

Publication number: WO2016122109A1
Application number: PCT/KR2015/013561
Authority: WO
Inventors: 박동현
Original assignee: 주식회사 아이티엘
Priority date: 2015-01-30
Filing date: 2015-12-11
Publication date: 2016-08-04
Also published as: KR20160094234A

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 supporting carrier aggregation between a serving cell in a licensed band and a serving cell in an unlicensed band, the method comprising the steps of: determining whether a collision between a plurality of periodic CSI reports occurs on subframe n; when a collision between the plurality of periodic CSI reports occurs, determining whether periodic CSI reports for a serving cell in an unlicensed band, among the plurality of periodic CSI reports, are valid; 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

Method and apparatus for performing CSI reporting for unlicensed serving cell in wireless communication system

The present invention relates to wireless communication, and more particularly, to a method and apparatus for performing channel state information (CSI) report for a serving cell of an unlicensed band in a wireless communication system.

The wireless communication system adjusts MCS and transmission power according to a given channel by using link adaptation in order to make full use of a given channel capacity. Here, link adaptation means that the modulation and channel coding schemes are changed according to the conditions of the radio link to achieve optimal communication performance. In order to perform such a link adaptation at the base station, periodic feedback of the channel state information of the terminal is required.

On the other hand, as the wireless communication traffic surges, small cells such as pico cells, femto cells, micro cells, and remote radio heads (RRHs) ), Relays, and repeaters are being actively used, but securing more frequencies is an urgent problem. Accordingly, a method of performing wireless communication using not only a licensed band (L-band) but also frequencies of an unlicensed band (U-band) such as a WiFi band has been discussed.

However, since the unlicensed band allows competitive access, the access method in the existing licensed band cannot be applied as it is, and the radio frame structure in the unlicensed band may be different from the radio frame structure in the licensed band.

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

The present invention relates to a method and apparatus for performing CSI reporting for a serving cell of an unlicensed band in a wireless communication system.

Another technical problem of the present invention is to provide an unlicensed band resource management method and apparatus in a wireless communication system.

Another technical problem of the present invention is to provide a periodic CSI reporting method and apparatus in a wireless communication system.

According to an aspect of the present invention, a periodic CSI of a terminal in a license assisted access (LAA) based wireless communication system supporting carrier aggregation between a serving cell of a licensed band and a serving cell of an unlicensed band (Channel State Information) Provides a reporting method. The method may include determining whether a plurality of periodic CSI reports collide on subframe n, and when the plurality of periodic CSI reports collide, validity of the periodic CSI report for a serving cell of an unlicensed band among the plurality of periodic CSI reports Determining whether one of the plurality of periodic CSI reports is based on a priority from among the remaining periodic CSI reports except for the periodic CSI report for a serving cell of an unlicensed band that is not valid; and And transmitting the selected one periodic CSI report to the base station.

According to another aspect of the present invention, periodic CSI reporting is performed 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. It provides a terminal to perform. The terminal determines whether a plurality of periodic CSI reports collide on subframe n, and when the plurality of periodic CSI reports collide, whether the periodic CSI report is valid for a serving cell of an unlicensed band among the plurality of periodic CSI reports. A processor for determining a plurality of periodic CSI reports and selecting one periodic CSI report based on a priority among remaining periodic CSI reports except for a periodic CSI report for a serving cell of an unlicensed unlicensed band, and the selected one It characterized in that it comprises a radio frequency unit (RF) for transmitting the periodic CSI report of the base station.

According to another aspect of the present invention, the periodicity of the base station in the License Assisted Access (LAA) based wireless communication system supporting carrier aggregation between the serving cell of the licensed band and the serving cell of the unlicensed band Provides a channel state information (CSI) reporting processing method. The processing method may include performing an RRC connection reconfiguration procedure for configuring a carrier of the licensed band and the carrier of the unlicensed band into serving cells, and if a plurality of periodic CSI reports collide on subframe n, serving of an unlicensed band. Receiving one periodic CSI report selected by the terminal based on the validity and priority of the periodic CSI report for the cell, and performing scheduling for the terminal based on the periodic CSI report. It is done.

According to the present invention, in addition to performing data transmission and reception through a licensed band in a wireless communication system, data transmission can be performed through an unlicensed band, thereby improving transmission efficiency.

In addition, according to the present invention, the terminal can perform efficient CSI reporting on the serving cell of the unlicensed band, and the base station is modulated and channel coding scheme according to the situation of the radio link with respect to the serving cell of the unlicensed band based on the CSI report. Can be controlled to achieve optimal communication performance.

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

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

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

4 illustrates an example of a case where a CA is configured between a serving cell of a licensed band and a serving cell of an unlicensed band and a periodic CSI report is collided.

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

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

7 illustrates a method of performing periodic CSI reporting according to another embodiment of the present invention.

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

Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings and examples, together with the contents of the present disclosure. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even though they are shown in different drawings. In addition, in describing the embodiments of the present specification, when it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present specification, the detailed description thereof will be omitted.

In addition, the present specification describes a wireless communication network, the operation performed in the wireless communication network is performed in the process of controlling the network and transmitting data in the system (for example, the base station) that is in charge of the wireless communication network, or the corresponding wireless Work may be performed in a terminal included in the network.

The wireless communication system 10 is widely deployed to provide various communication services such as voice and packet data. The wireless communication system 10 includes at least one base station 11 (evolved-NodeB, eNB). Each base station 11 provides a communication service for

specific cells

15a, 15b, and 15c. The cell can in turn be divided into a number of regions (called sectors).

The user equipment (UE) 12 may be fixed or mobile, and may include a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, and a PDA. (personal digital assistant), wireless modem (wireless modem), a handheld device (handheld device) may be called other terms. 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, an femto base station, a home node B, a relay, and the like. A cell is meant to encompass all of the various coverage areas such as megacell, macrocell, microcell, picocell, femtocell, and the like.

Hereinafter, downlink (DL) means communication from the base station 11 to the terminal 12, and uplink (UL) means communication from the terminal 12 to the base station 11. In downlink, the transmitter may be part of the base station 11 and the receiver may be part of the terminal 12. In uplink, the transmitter may be part of the terminal 12 and the receiver may be part of the base station 11. There is no limitation on the multiple access scheme applied to the wireless communication system. Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA (SC-FDMA), OFDM-FDMA, OFDM-TDMA For example, various multiple access schemes such as OFDM-CDMA may be used. The uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme that is transmitted using different times, or may use a frequency division duplex (FDD) scheme that is transmitted using different frequencies.

Carrier aggregation (CA) supports a plurality of carriers, also referred to as spectrum aggregation or bandwidth aggregation. Individual unit carriers bound by carrier aggregation are called component carriers (CCs). The serving cell may be defined as an element frequency band that may 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 primary serving cell is one that provides security input and non-access stratum (NAS) mobility information in a radio resource control (RRC) establishment or reestablishment state. It means a serving cell. According to the capabilities of the terminal, at least one cell may be configured to form a set of serving cells together with the main serving cell, wherein the at least one cell is called a secondary serving cell. The set of serving cells configured for one terminal may consist of only one main serving cell or 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 primary carrier (DL PCC), and the uplink component carrier corresponding to the main serving cell is referred to as an uplink major carrier (UL PCC). In the downlink, the component carrier corresponding to the secondary serving cell is called a downlink sub-component carrier (DL SCC), and in the uplink, the component carrier corresponding to the secondary serving cell is called an uplink sub-component carrier (UL SCC). do. Only one DL CC may correspond to one serving cell, and a DL CC and a UL CC may correspond together.

On the other hand, since a small cell generally serves a smaller area than a macro cell, it is advantageous to a macro cell in terms of performance that can be provided for a single terminal. As the wireless communication traffic surges, the small cells as described above are actively used, but securing more frequencies is an urgent problem for improving performance.

In this regard, a method of performing wireless communication using not only a licensed band but also frequencies of an unlicensed band such as a WiFi band has been discussed. To this end, the present invention proposes a method for performing wireless communication in an unlicensed band in consideration of support / management / operation of a licensed band communication technique for smoothly supporting wireless communication in an unlicensed band.

Hereinafter, in the present invention, LAA (License Assisted Access) refers to carrier aggregation for one or more SCells operating in an unlicensed band or unlicensed spectrum based on the control of a PCell operating in a licensed band or spectrum. A wireless communication technique that supports operation. In the LAA deployment scenario, the configured SCell on the unlicensed band may be located within macro coverage or may be located outside of macro coverage. In addition, the SCell configured in the unlicensed band may be arranged in an indoor place such as a general home or a complex, or may be arranged in an outdoor place. In addition, the carriers of the licensed band and the unlicensed band may be co-location or non-co-located with each other. Here, the same location location may mean that a base station operating a carrier of a licensed band and a base station operating a carrier of an unlicensed band are the same base station or adjacent to RF (radio frequency) units.

If carriers in the licensed and unlicensed bands exist at non-uniform location locations, the first base station operating the carriers of the licensed band and the second base station operating the carriers of the unlicensed band are ideally backhauled to support smooth carrier aggregation. ideal backhaul). Here, the ideal backhaul may mean a backhaul having a delay of 2.5 μs or less and a capacity of 10 Gbps or more, and the criteria for this may vary according to a communication environment and a wireless communication protocol.

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

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

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

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

Meanwhile, the terminal may establish dual connectivity through two or more base stations among the base stations configuring at least one serving cell. Dual connectivity is an operation in which the terminal consumes radio resources provided by at least two different network points (eg, macro base station and small base station) in a radio resource control connection (RRC_CONNECTED) mode. If dual connectivity is possible, dual connectivity between macro cell and small cell (s) may be configured in the above scenarios.

On the other hand, the regulations and standards to be followed in order to use the unlicensed band may be defined differently for each region and country. For example, the nominal channel bandwidth of the unlicensed carrier may be at least 5 MHz. And in the unlicensed band, the channel bandwidth occupies substantially 80% to 100% of the nominal channel bandwidth. Therefore, the unlicensed band used in the LAA system for the efficiency of the overall wireless communication system may support a bandwidth of at least 10MHz or 20MHz, and may not support a bandwidth below 5MHz.

On the other hand, there may be a variety of contention-based channel access method for the unlicensed band, the channel access mechanism (mechanism) for the unlicensed band according to the present invention includes the following.

The channel access mechanism according to the present invention provides opportunistic channel access. In order to access the opportunity channel, a wireless channel device applies a clear channel assessment (CCA) before using the channel. This is to avoid concurrent transmission on the same channel as other RLAN (Radio Local Area Network) systems. Here, the CCA represents a procedure of determining whether the channel is in the state of channel interference or channel occupancy, that is, whether the channel is busy or idle through energy scan or detection of the channel. CCA may be performed based on whether energy was detected during a certain monitoring time. Here, it is possible to determine whether the corresponding channel is busy or idle by comparing an equivalent isotropic radio power (EIRP) obtained through energy detection with a predefined CCA threshold. CCA checks can be performed based on "energy detection" for CCA monitoring times of 20 μs or more. The channel access mechanism according to the present invention based on the carrier sense (CS), etc. may be referred to as List Before Talk (LBT).

ECCA may be used in LBT. The ECCA performs energy scans or detections by the duration of a factor N multiplied by a CCA observation time to determine whether the channel is in channel interference or channel occupancy. May be indicated. Herein, the factor N may be a random factor. The factor N may represent the number of clear idle slots. Intact idle slots consequently result in a full idle period, and the idle period needs to be monitored before starting transmission.

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

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

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

Referring to FIG. 3, the CCA is performed in the FBE and resources that can be obtained through the FBE are defined as one frame structure. In an FBE, an idle period and a channel occupancy time are included in one frame period. The idle period here may be at least 5% of the channel occupation time. Also the children's period includes CCA (surveillance) time. Here, the CCA time may be, for example, 20 μs or more. In FBE, CCA is performed once in one frame.

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

On the other hand, in performing the TPC (Transmit Power Control) in the unlicensed band, many radio equipment using the unlicensed band must perform at least a certain level (for example, 3dB) power control. Through this, interference between wireless devices can be controlled in the unlicensed band.

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

Table 1

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

Since the DFS requirement is based on long period values, the requirement can be met through higher layer signaling such as an SCell deactivation / deconfiguration message.

In addition, since many carriers in the unlicensed band can be used between various wireless communication systems, the transmitting node should be able to appropriately select one or some carriers in the unlicensed band in order to reduce fairness and interference between wireless devices. . This may be called a carrier selection operation (in an unlicensed band).

In addition, the occupation of radio resources in the unlicensed band is discontinuous. For example, in Europe and Japan, the occupation of radio resources in the unlicensed band should be discontinuous. Discontinuous transmission is required for the LAA system according to the present invention to operate based on a global single framework. Support is required.

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, it is necessary to periodically feedback the channel state information of the terminal, the terminal performs the CSI report. CSI reporting may be performed through a physical uplink control channel (PUCCH) carrying uplink control information. Alternatively, when the Physical Uplink Shared Channel (PUSCH) is transmitted, CSI reporting may be performed through the PUSCH.

CSI reporting may be performed periodically according to a period determined by a higher layer. Such CSI reporting may be referred to as periodic CSI reporting. The terminal may be semi-statically set by the higher layer signal to periodically feed back different CSI type elements CQI, PMI, RI, and PTI through the PUCCH.

Channel Quality Indicator (CQI) provides information on link adaptive parameters that a 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 characteristics of the terminal receiver and signal to interference plus noise ratio (SINR). The base station may determine the modulation (QPSK, 16-QAM, 64-QAM, etc.) and coding rate to be applied to the downlink channel using the CQI. CQI can be generated in several ways. For example, a method of quantizing and feeding back a channel state as it is, a method of calculating a feedback to a signal to interference plus noise ratio (SINR), and a method of notifying a state that is actually applied to a channel such as a modulation coding scheme (MCS) may be used. have. When the CQI is generated based on the MCS, the MCS includes a modulation scheme, a coding scheme, a coding rate, and the like.

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

The rank indication (RI) is information about a rank (ie, 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. In other words, the fed back 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 fewer times than the CQI. The transmission period of the RI may be a multiple of the CQI / PMI transmission period.

When the 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 may be performed with different periods and offsets independently of each serving cell, and in this case, periodic CSI reporting for a plurality of serving cells may be performed in one time instance (ie, the same sub). On a frame) (ie, collision). In this case, CSI reporting for one serving cell may be performed based on priority.

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

TABLE 2

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

As shown in Table 2, when periodic CSI reports for multiple serving cells collide on the same time instance, periodic CSI reporting having a high priority is performed based on a priority determined according to a CSI report type. Meanwhile, according to the fourth priority, when conflicting periodic CSI reports have the same priority at the first to third priorities, the periodicity for the serving cell having the relatively lowest serving cell index is given. CSI reporting is performed. That is, according to the priority, periodic CSI reports of several serving cells are dropped, and periodic CSI reports for one serving cell are delivered to the base station through PUCCH (or corresponding PUSCH if PUSCH transmission is configured), The base station may use the corresponding periodic CSI report for DL scheduling. The PUCCH may be transmitted on a PCell or an SCell in which transmission of the PUCCH is configured.

On the other hand, CSI reporting information is different depending on the type. Table 3 below describes the CSI reporting type in Table 2.

TABLE 3

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

Meanwhile, in the LAA scenario, UL / DL transmission / reception of SCells configured on the unlicensed band is possible after performing channel LBT. That is, UL / DL transmission and reception are possible after acquiring (or occupying) the frequency and time on the SCell of the unlicensed band based on the LBT. CSI reporting is generally performed for activated CCs. On the other hand, in the LAA-based communication, when considering carrier selection and LBT performance of the base station, it is possible to consider the configuration state of two terminals as follows.

Alt 1. Configuration of serving cell (s) in unlicensed band (by RRC layer) => Activation of configured serving cell (s) (by MAC (Media Access Control) layer) => LBT (on / off) based channel acquisition . Here, on of LBT indicates channel acquisition, and off indicates no channel acquisition.

Alt 2. Configuration of Serving Cell (s) in Unlicensed Band (by RRC Layer) => LBT (on / off) Based Channel Acquisition

The difference between Alt 1 and Alt 2 described above is whether activation signaling in the MAC layer for the configured serving cell (s) of the unlicensed band is considered for power saving of the terminal. The periodic CSI reporting method according to the present invention may be performed for a serving cell requiring CSI reporting based on a result of performing LBT regardless of the configuration state of the terminal.

4 illustrates an example of a case where a CA is configured between a serving cell of a licensed band and a serving cell of an unlicensed band and a periodic CSI report is collided. 4 shows that PCell, SCell # 1, and SCell # 2 are CA configured in a terminal, PCell uses frequency f1 of licensed band, SCell # 1 uses frequency f2 of unlicensed band, and SCell # 2 uses frequency of unlicensed band. This is an example of using f3.

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

In the LAA environment, the channel acquisition operation through the LBT is performed on the SCell of the unlicensed band, and UL / DL transmission and reception are possible only when the radio resources are occupied (channel acquisition) on the SCell # 1 and SCell # 2. . Therefore, in considering the collision of the periodic CSI reporting in the LAA environment, whether or not the channel of the SCell of the corresponding unlicensed band as well as the periodic CSI reporting related parameters set through semi-static RRC signaling ) Must be further based on

Anti-static BS via RRC signaling for each serving cell, the CQI / PMI report periodically (for TM1-9) or each of the serving cell in each CSI process (if the TM10) by cqi-pmi-ConfigIndex (I _{CQI / PMI)} values To set the period N _pd and offset N _{OFFSET, RI} (subframe unit) to the UE. In addition, RI similarly sets the period M _RI and the relative offset N _{OFFSET, RI} values of the RI report to the UE through semi-static RRC signaling ri-ConfigIndex (I _RI ). Therefore, the timing for periodic reporting of CQI / PMI and RI is determined by using a table indicating the above RRC signaling and the corresponding periodic value and offset value. Tables 4 and 5 below show examples of tables for determining a reporting period of CQI / PMI and RI corresponding to an RRC parameter transmitted from a base station to a terminal, respectively.

Table 4

I _{CQI / PMI}	Value of N _pd	Value of N _{OFFSET, CQI}
0≤I _{CQI / PMI} ≤1	2	I _{CQI / PMI}
2≤I _{CQI / PMI} ≤6	5	I _{CQI / PMI} -2
7≤I _{CQI / PMI} ≤16	10	I _{CQI / PMI} -7
17≤I _{CQI / PMI} ≤36	20	I _{CQI / PMI} -17
37≤I _{CQI / PMI} ≤76	40	I _{CQI / PMI} -37
77≤I _{CQI / PMI} ≤156	80	I _{CQI / PMI} -77
157≤I _{CQI / PMI} ≤316	160	I _{CQI / PMI} -157
I _{CQI / PMI} = 317	Reserved
318≤I _{CQI / PMI} ≤349	32	I _{CQI / PMI} -318
350≤I _{CQI / PMI} ≤413	64	I _{CQI / PMI} -350
414≤I _{CQI / PMI} ≤541	128	I _{CQI / PMI} -414
542≤I _{CQI / PMI} ≤1023	Reserved

Table 5

I _RI	Value of M _RI	Value of N _{OFFSET, RI}
0≤I _RI ≤160	One	-I _RI
161≤I _RI ≤321	2	-(I _RI -161)
322≤I _RI ≤482	4	-(I _RI -322)
483≤I _RI ≤643	8	-(I _RI -483)
644≤I _RI ≤804	16	-(I _RI -644)
0≤I _RI ≤965	32	-(I _RI -805)
0≤I _RI ≤1023	Reserved

Referring to Table 4, in the PCell frame structure type (frame structure 1) of the FDD or FDD-TDD mode, N _pd and N _{OFFSET, CQI} may be set as shown in the above table according to I _{CQI / PMI} . In this case, M _RI and N _{OFFSET, RI} may be set as shown in the table according to I _RI .

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

Referring to FIG. 5, a hole is a periodic CSI reporting timing (subframe) according to CSI reporting related parameters, and a dot is a timing at which a substantially valid CSI reporting can be performed. As shown in FIG. 5, the timing of the periodic CSI report for the PCell and the timing of the periodic CSI report for the SCell # 1 may collide at the time of the identification number 500, but the channel acquisition is not performed in the SCell # 1 of the unlicensed band. In effect, a substantially valid periodic CSI report cannot be performed. That is, even if periodic CSI reporting is performed without channel acquisition in SCell # 1 of the unlicensed band, the measured value is out-of-range or incorrect. Therefore, only periodic CSI reporting for the PCell is effectively performed in this case.

On the other hand, at the time of identification number 510, the timing of the periodic CSI reporting for the PCell, the timing of the periodic CSI reporting for the SCell # 1, and the timing of the periodic CSI reporting for the SCell # 2 collide, and the SCell # 1 and the SCell of the unlicensed band are collided. In # 2, since the channel is acquired, valid periodic CSI reporting may be performed.

Therefore, a substantial collision of the periodic CSI report for the PCell, the periodic CSI report for SCell # 1, and the periodic CSI report for SCell # 2 occurs, and the periodic CSI report for all serving cells cannot be performed, that is, the PCell. Since the UE for which periodic CSI reporting is to be performed through the PUCCH is possible only CSI reporting for one serving cell, a method for solving this problem should be defined.

In the present invention, for effective periodic CSI reporting, a separator for serving cells configured on a licensed carrier (L-carrier) and serving cells configured on an unlicensed carrier (U-carrier) may be provided. That is, an indicator indicating whether the corresponding SCell is configured on the U-carrier may be used in each SCell configuration. The indicator may be an RRC related parameter and may be indicated through an Evolved Absolute Radio Frequency Channel Number (E-ARFCN) value. That is, it may be indicated whether the SCell set together with the corresponding value is configured on the licensed carrier or the unlicensed carrier according to whether the E-ARFCN value corresponds to the value of the unlicensed carrier.

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

If the LAA operation is configured with an improved CA configuration for the UE and the plurality of periodic CSI timings are triggered in subframe n (PUCCH transmission subframe), the serving cell (s) corresponding to the L-carrier are excluded. (Determined to be valid), and among the serving cell (s) corresponding to the remaining U-carriers, subframe n of the serving cell is a subframe (on) occupied (channel acquired) by the base station, or at least a subframe nk If subframes (including nk) were subframes (on) occupied by the base station (k> 0), it is determined that the (periodic) CSI report for the serving cell is valid.

That is, when at least one subframe of at least subframe nk before subframe nk or subframe n of the serving cell (s) configured in the U-carrier is occupied by the base station, the subframe n The (periodic) CSI report in can be considered valid. That is, in this case, the CQI value included in the CSI report of the serving cell is not out-of-range.

In addition, according to the present invention, the periodic CSI report on the serving cell (PCell or SCell) on the L-carrier, and the periodic CSI report on the serving cell (SCell) on the U-carrier determined as valid above (hereinafter, unlicensed band or In case of collision, the effective periodic CSI reporting for the serving cell on the U-carrier is higher than the periodic CSI reporting for the serving cell on the L-carrier. It may be set (or defined) to have priority. Since the channel access opportunity is guaranteed on the U-carrier more rarely than the L-carrier through carrier selection and LBT, the subframes occupied by the serving cell on the U-carrier are secured by securing an opportunity for reliable CSI reporting. This is to ensure maximum utilization of resources on the market. This is because the CSI of the serving cells on the U-carrier, which should be opportunistic to be transmitted, may be adversely affected when the CSI reports of the serving cells on the L-carrier occupy the occupied L-carrier are dropped. to be. In addition, this may be because the LAA introduction motivation to off-load more data transmission onto the u-carrier may be inconsistent.

A method of performing periodic CSI reporting considering a serving cell of an unlicensed band according to the present invention will be described in detail as follows.

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

If a collision occurs in S600, the terminal extracts the effective periodic CSI report for the serving cell on the U-carrier (S610). For example, when the subframe n of the corresponding serving cell is a subframe occupied by the base station (channel obtained), the UE may determine that periodic CSI reporting in subframe n for the corresponding serving cell is valid. Can be.

As another example, when the UE occupies at least one subframe among the subframes nk before the subframe nk of the serving cell among the serving cells corresponding to the U-carriers (k> 0), Periodic CSI reporting 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 period and the subframe corresponding to the CSI reporting timing of the current period. Thus, the value of k is less than or equal to the CSI reporting period value. For example, when the CSI report is performed with a 10 ms period, the CSI report is an arbitrary value between the subframe n-10 and the subframe n (e.g. 0 <k <= 10). If there is no effective periodic CSI report in S610, the UE determines that the periodic CSI reports for the serving cells on the U-carriers are not performed, and, among the periodic CSI reports for the serving cells on the L-carrier, The periodic CSI report is selected for the last one serving cell based on the ranking (S640). Priority between the periodic CSI reports for the serving cells on the L-carrier applies the priority according to Table 2.

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

Subsequently, when there are a plurality of serving cells (on U-carriers) having effective periodic CSI reporting, the terminal applies the priority of each CSI report type and serving cell index according to Table 2 among the plurality of serving cells. (S630).

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

On the other hand, when a collision does not occur in S600, the UE may select and perform periodic CSI reporting on one serving cell that currently occurs.

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

Table 6

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, as the first priority, it is determined whether the periodic CSI reporting is related to the serving cell configured in the U-carrier or the serving cell configured in the L-carrier, and the periodic CSI reporting on the serving cell configured in the U-carrier. CSI reporting has a higher priority. That is, if the periodic CSI reporting for the serving cell configured for the U-carrier corresponding to the effective periodic CSI report collides in one subframe, the periodicity for the serving cell configured for the L-carrier CSI reports are dropped. Thereafter, periodic CSI reports with higher priorities in the second, third, and fourth order are selected until only one periodic CSI report remains, and periodic CSI reports with lower priorities are dropped. If a plurality of periodic CSI reports still remain after the fourth priority, the periodic CSI report for the serving cell having the lowest serving cell index is selected and performed based on the fifth priority.

This is a method of relatively prioritizing CSI measurement for opportunistic transmission. That is, CSI reports for SCells configured on the U-carrier are L regardless of the CSI report type or the serving cell index of the SCell. As an example, the priority is given to CSI reports for serving cells (PCell / SCells) configured on a carrier. This configuration allows offloading data from the L-carrier to the U-carrier to distribute the L-carrier traffic. Therefore, since more CSI information is required to perform more data transmission in the U-carrier, the U-carrier can take priority over the CSI corresponding to the L-carrier.

Referring to FIG. 7, the terminal identifies collisions of valid periodic CSI reports for a plurality of serving cells configured in the corresponding terminal (S700). That is, the UE checks whether a plurality of CSI reporting timings collide with each other in subframe n.

If there is a collision as a result of the check, the UE extracts the effective periodic CSI report for the serving cell on the U-carrier (S710). The terminal occupies the subframe n of the corresponding serving cell by the base station (channel obtained). In the case of a subframe (on), it may be determined that periodic CSI reporting in subframe n for the corresponding serving cell is valid.

As another example, when the UE occupies at least one subframe among the subframes nk before the subframe nk of the serving cell among the serving cells corresponding to the U-carriers (k> 0), Periodic CSI reporting in subframe n for the serving cell may be determined to be valid.

That is, the timing of the periodic CSI reporting for the PCell and the CSI reporting timing of the SCell of the unlicensed band overlap at a predetermined time point, but since the channel is acquired by the SCell, it is determined to be a valid periodic CSI reporting.

On the other hand, if there is no effective periodic CSI report, the UE determines that the periodic CSI reports for the serving cells on the U-carriers is not performed, the priority between the periodic CSI reports for the serving cells on the L-carrier Select periodic CSI reporting for the last one serving cell based on.

Thereafter, if a plurality of CSI reports remain, CSI report type based priority is applied (S720). For example, the terminal may apply the priority based on the priority rules of first to third of Table 2 described above.

Here, when periodic CSI reports having the same priority exist, the priority based on the carrier type and / or the serving cell index is applied (S730). That is, when the UE has periodic CSI report (s) for the serving cell (s) on the L-carriers and the effective periodic CSI report (s) for the serving cell (s) on the U-carriers, the UE The effective periodic CSI report (s) for the serving cell (s) on the U-carriers are applied at a higher priority than the periodic CSI report (s) for the serving cell (s) on the L-carriers. That is, the UE drops the periodic CSI report (s) for the serving cell (s) on the L-carriers. Subsequently, when periodic CSI reports with the same priority remain, the UE may apply the CSI report for the serving cell having the lowest serving cell index based on the serving cell index to have a higher priority.

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

Meanwhile, if there is no collision in S700, the UE may select and perform periodic CSI reporting on one serving cell that has occurred at present, and if only one periodic CSI report is left as a result of prioritizing in S720, immediately proceeds to step S740. I can move it.

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

TABLE 7

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, when the priority is maintained based on the CSI reporting type, but there are still a plurality of CSI reports even though the third priority is completed, the periodic CSI reporting on the U-carrier is higher in consideration of the carrier type. This method considers the priority of CSI measurement for opportunistic transmission by having a ranking. If a plurality of CSI reports still remain afterwards, the last one CSI report may be selected based on the serving cell index.

In addition, the priority rule between periodic CSI reports according to another embodiment of the present invention may be represented as Table 8 below.

Table 8

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, another embodiment of the present invention first considers RI and first wideband PMI information that should be considered most important for DL scheduling, and then considers carrier type. . If there is no RI and the first wideband PMI information, even if the remaining CSI information is received later, scheduling may be disrupted. In order to prevent this, the RI and first wideband PMI information may be considered first.

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

Table 9

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, another embodiment of the present invention first considers RI and first wideband PMI information that should be considered most important for DL scheduling, and then selects other wideband CQI / PMI information. After consideration, the carrier type is considered. If there is no RI and first wideband PMI information or other wideband CQI / PMI information, even if the remaining CSI information is received later, scheduling may be disrupted. To prevent this, the RI and first wideband PMI information and Other wideband CQI / PMI information may be considered in preference to carrier type information.

As described above, in the example of the present invention, it is described that the periodic CSI report for the serving cells configured in the U-carrier has a higher priority than the L-carrier periodic CSI report within the priority according to the carrier type.

Meanwhile, in another embodiment of the present invention, if the data transmission on the serving cell configured in the L-carrier is prioritized, the periodic CSI report for the serving cells configured in the L-carrier has a higher priority than the periodic CSI report of the U-carrier. It may also operate to have.

Referring to FIG. 8, the base station 800 includes a memory 805, a processor 810, and an RF unit 820. The memory 805 is connected 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 a radio signal. Processor 810 implements the proposed functions, processes, and / or methods for performing operations in accordance with the present invention. In the above-described embodiments, the operation of the base station may be implemented by the control of the processor 810.

The processor 810 includes a serving cell component 811, an activation processor 812, a CCA performer 813, and a PHY processor 814.

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

The activation processor 812 may generate an activation / deactivation indicator for the SCells configured in the terminal 850 and transmit the activation / deactivation indicator to the terminal through the RF unit 820. The activation / deactivation indicator may be included in a MAC message and transmitted to the terminal through the PCell.

The CCA execution unit 813 performs a channel acquisition procedure for the SCells of the activated unlicensed band. The channel acquisition procedure may be performed based on CCA. If the activation procedure for the SCells in the unlicensed band is omitted by an appointment between the terminal 850 and the base station 800, the CCA performing unit 813 may perform SCells in the unlicensed band according to a predefined criterion regardless of activation. A channel acquisition procedure for may be performed.

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

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

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

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

In addition, the PHY processing unit 863 may perform data transmission / reception with the base station 800 on the acquired (occupied) subframes of the SCell of the unlicensed band through the RF unit 870.

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

Claims

In a method of reporting periodic channel state information (CSI) of a terminal in a license assisted access (LAA) based wireless communication system supporting carrier aggregation between a serving cell of a licensed band and a serving cell of an unlicensed band In

Determining whether a plurality of periodic CSI reports collide on subframe n;

When the plurality of periodic CSI reports collide, determining whether the periodic CSI report is valid for a serving cell of an unlicensed band among the plurality of periodic CSI reports;

Selecting one of the plurality of periodic CSI reports based on priority among the remaining CSI reports except for the periodic CSI report for the serving cell of an unlicensed band that is not valid; And

And transmitting the selected one periodic CSI report to a base station.
The method of claim 1,

The validity of the periodic CSI reporting for the serving cell of the unlicensed band is determined based on whether the subframe n of the serving cell of the unlicensed band is a channel acquired subframe.
The method of claim 1,

Whether the periodic CSI report is valid for the serving cell of the unlicensed band is determined based on whether at least one subframe of subframes n-4 to subframe n of the serving cell of the unlicensed band is a channel acquired subframe. Characterized in that the periodic CSI reporting method.
The method of claim 1,

The priority is characterized in that based on the following table (T1),

(T1)

Periodic CSI Reporting Method.
The method of claim 1,

The priority is characterized in that based on the following table (T2),

(T2)

Periodic CSI Reporting Method.
The method of claim 1,

The priority is characterized in that based on the following table (T3),

(T3)

Periodic CSI Reporting Method.
A terminal for performing periodic CSI reporting in a License Assisted Access (LAA) based wireless communication system supporting carrier aggregation between a serving cell of a licensed band and a serving cell of an unlicensed band,

It is determined whether a plurality of periodic CSI reports collide on subframe n, and when the plurality of periodic CSI reports collide, it is determined whether the periodic CSI report is valid for a serving cell of an unlicensed band among the plurality of periodic CSI reports. A processor that selects one periodic CSI report based on a priority among the remaining periodic CSI reports except for the periodic CSI report for a serving cell of an unlicensed band in which the plurality of periodic CSI reports are not valid; And

And a radio frequency unit (RF) for transmitting the selected one periodic CSI report to a base station.
The method of claim 7, wherein

And the processor determines whether the periodic CSI report is valid for the serving cell of the unlicensed band based on whether the subframe n of the serving cell of the unlicensed band is a channel acquired subframe.
The method of claim 7, wherein

The processor determines whether or not validity of periodic CSI reporting for a serving cell of the unlicensed band is at least one subframe of subframes n-4 to subframe n of the serving cell of the unlicensed band is a channel acquired subframe. Terminal, characterized in that determined based on.
The method of claim 7, wherein

Wherein the processor determines the priority based on the following table (T4),

(T4)

Terminal.
The method of claim 7, wherein

The processor is characterized in that determining the priority based on the following table (T5),

(T5)

Terminal.
The method of claim 7, wherein

Characterized in that the processor determines the priority based on the following table (T6),

(T6)

Terminal.
A method for processing periodic channel state information (CSI) reporting of a base station in a license assisted access (LAA) based wireless communication system supporting carrier aggregation between a serving cell of a licensed band and a serving cell of an unlicensed band To

Performing an RRC connection reconfiguration procedure for configuring the licensed carrier and the unlicensed carrier as serving cells;

When a plurality of periodic CSI reports collide on subframe n, receiving one periodic CSI report selected by the terminal based on the validity and priority of the periodic CSI report for the serving cell of the unlicensed band; And

Performing scheduling for the terminal based on the periodic CSI report.