WO2016013781A1 - Method for transmitting uplink data in unlicensed band cell, and apparatus therefor - Google Patents

Abstract

The present invention relates to a method for transmitting uplink data of a terminal, and an apparatus therefor. More particularly, the present invention relates to a method and an apparatus for transmitting and receiving data using an unlicensed band frequency. In particular, the present invention provides a method and an apparatus for transmitting, by a terminal, uplink data, the method comprising the steps of: configuring carrier aggregation including an unlicensed band cell which uses a frequency shared by one or more communication systems; receiving scheduling information for uplink transmission in the unlicensed band cell; determining whether the unlicensed band cell is within an available section; and transmitting the uplink data on the basis of the scheduling information if the unlicensed band cell is within an available section.

Description

Method and apparatus for transmitting uplink data in unlicensed band cell

The present invention relates to a method and apparatus for uplink data transmission of a terminal. More particularly, the present invention relates to a method and an apparatus for transmitting and receiving data using an unlicensed band frequency.

As communication systems have evolved, consumers, such as businesses and individuals, have used a wide variety of wireless terminals. Mobile communication systems such as LTE (Long Term Evolution) and LTE-Advanced of the current 3GPP series are high-speed and large-capacity communication systems that can transmit and receive various data such as video and wireless data beyond voice-oriented services. The development of technology capable of transferring large amounts of data is required. As a method for transmitting a large amount of data, data can be efficiently transmitted using a plurality of cells.

In this situation, in order to transmit a large amount of data at high speed and to reliably transmit and receive data in an environment in which a large number of terminals are concentrated in a specific base station, a technique of deploying a large number of small base stations having a relatively narrow coverage such as a small cell is discussed. There is a situation.

In addition, a discussion on dual connectivity for communicating with a terminal using such a small cell and a conventional macro cell is in progress. In this dual connectivity situation, the terminal may perform wireless communication with a plurality of base stations.

Meanwhile, the necessity of using a frequency band shared with a plurality of communication systems is increasing. This is due to the lack of the frequency band used in the mobile communication system and the need for large data processing, and researches on a method for using the shared frequency and the unlicensed band used by the Wi-Fi system in the mobile communication system are in progress.

SUMMARY OF THE INVENTION The present invention devised in the above-described background proposes a method and apparatus for quickly transmitting a terminal while transmitting uplink data in an unlicensed band cell while maintaining coexistence with other communication systems.

In addition, the present invention is to propose the operation of the terminal and the base station when the unlicensed band cell for the uplink data transmission is unavailable period.

According to an aspect of the present invention, there is provided a method for transmitting uplink data by a user equipment, the method comprising: configuring a carrier aggregation including an unlicensed band cell using a frequency shared by at least one communication system and in an unlicensed band cell. Receiving scheduling information for uplink transmission of the UE; determining whether the unlicensed band cell is an available interval; and if the unlicensed band cell is an available interval, transmitting uplink data based on the scheduling information. Provide a way to.

In addition, the present invention provides a method for receiving a base station uplink data, comprising the steps of configuring a carrier aggregation in the terminal including an unlicensed band cell using a frequency shared by one or more communication systems and uplink in the unlicensed band cell The method includes transmitting scheduling information for transmission and receiving uplink data transmitted from the terminal based on the scheduling information and whether the unlicensed band cell is available.

In addition, the present invention provides a terminal for transmitting uplink data, including the unlicensed band cell using a frequency shared by one or more communication systems, the control unit for configuring carrier aggregation and scheduling for uplink transmission in the unlicensed band cell If the receiving unit for receiving the information and the unlicensed band cell is an available period, including a transmitting unit for transmitting uplink data based on the scheduling information, the control unit provides a terminal device for further determining whether the unlicensed band cell is available period do.

In addition, the present invention provides a base station for receiving uplink data, including an unlicensed band cell using a frequency shared by one or more communication systems to control the uplink transmission in the unlicensed band cell and the control unit to configure carrier aggregation The present invention provides a base station apparatus including a transmitter for transmitting scheduling information for receiving and a receiver for receiving uplink data transmitted from a terminal based on scheduling information and whether an unlicensed band cell is available.

As described above, the present invention provides an effect of transmitting and receiving uplink data in an unlicensed band cell and quickly transmitting and receiving while maintaining coexistence with other communication systems.

In addition, when the uplink data is transmitted, the present invention provides an effect that can be accurately transmitted even when the corresponding unlicensed band cell is unavailable.

1 is a view for explaining the ETSI LBT related standards.

FIG. 2 is a diagram for describing an uplink HARQ operation.

3 is a diagram illustrating an example of unlicensed band cell merging to which the present invention can be applied.

4 is a view for explaining the operation of the terminal according to an embodiment of the present invention.

5 is a diagram illustrating an uplink data transmission processing procedure of a terminal according to another embodiment of the present invention.

6 is a diagram for explaining an uplink data transmission processing procedure according to another embodiment of the present invention.

7 is a diagram for explaining an uplink data transmission processing procedure according to another embodiment of the present invention.

8 is a diagram illustrating a section of an unlicensed band cell of the present invention.

9 is a diagram illustrating an uplink data transmission processing procedure of a terminal according to another embodiment of the present invention.

10 is a view for explaining the operation of the base station according to another embodiment of the present invention.

11 is a view for explaining a terminal configuration according to another embodiment of the present invention.

12 is a view for explaining the configuration of a base station according to another embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data, and the like. The wireless communication system includes a user equipment (UE) and a base station (base station, BS, or eNB). In the present specification, a user terminal is a generic concept meaning a terminal in wireless communication. In addition, user equipment (UE) in WCDMA, LTE, and HSPA, as well as mobile station (MS) in GSM, user terminal (UT), and SS It should be interpreted as a concept that includes a subscriber station, a wireless device, and the like.

A base station or a cell generally refers to a station that communicates with a user terminal, and includes a Node-B, an evolved Node-B, an Sector, a Site, and a BTS. Other terms such as a base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell may be called.

In other words, in the present specification, a base station or a cell is a generic meaning indicating some areas or functions covered by a base station controller (BSC) in CDMA, a Node-B in WCDMA, an eNB or a sector (site) in LTE, and the like. It should be interpreted as, and it is meant to cover all the various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, small cell communication range.

Since the various cells listed above have a base station for controlling each cell, the base station may be interpreted in two senses. i) the device providing the megacell, the macrocell, the microcell, the picocell, the femtocell, the small cell in relation to the wireless area, or ii) the wireless area itself. In i) all devices which provide a given wireless area are controlled by the same entity or interact with each other to cooperatively configure the wireless area to direct the base station. The eNB, RRH, antenna, RU, LPN, point, transmit / receive point, transmit point, receive point, and the like, according to the configuration of the radio region, become an embodiment of the base station. In ii), the base station may indicate the radio area itself to receive or transmit a signal from a viewpoint of a user terminal or a neighboring base station.

Therefore, megacells, macrocells, microcells, picocells, femtocells, small cells, RRHs, antennas, RUs, low power nodes (LPNs), points, eNBs, transmit / receive points, transmit points, and receive points are collectively referred to as base stations. do.

In the present specification, the user terminal and the base station are two transmitting and receiving entities used to implement the technology or technical idea described in this specification in a comprehensive sense and are not limited by the terms or words specifically referred to. The user terminal and the base station are two types of uplink or downlink transmitting / receiving subjects used to implement the technology or the technical idea described in the present invention, and are used in a generic sense and are not limited by the terms or words specifically referred to. Here, the uplink (Uplink, UL, or uplink) refers to a method for transmitting and receiving data to the base station by the user terminal, the downlink (Downlink, DL, or downlink) means to transmit and receive data to the user terminal by the base station It means the way.

There is no limitation on the multiple access scheme applied to the wireless communication system. Various multiple access techniques such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM-TDMA, OFDM-CDMA Can be used. One embodiment of the present invention can be applied to resource allocation in the fields of asynchronous wireless communication evolving to LTE and LTE-Advanced through GSM, WCDMA, HSPA, and synchronous wireless communication evolving to CDMA, CDMA-2000 and UMB. The present invention should not be construed as being limited or limited to a specific wireless communication field, but should be construed as including all technical fields to which the spirit of the present invention can be applied.

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.

In addition, in systems such as LTE and LTE-Advanced, a standard is configured by configuring uplink and downlink based on one carrier or a pair of carriers. The uplink and the downlink include a Physical Downlink Control CHannel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel (PHICH), a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control CHannel (EPDCCH), and the like. Control information is transmitted through the same control channel, and data is configured by a data channel such as a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH).

On the other hand, control information may also be transmitted using an enhanced PDCCH (EPDCCH or extended PDCCH).

In the present specification, a cell means a component carrier having a coverage of a signal transmitted from a transmission / reception point or a signal transmitted from a transmission point or a transmission / reception point, and the transmission / reception point itself. Can be.

A wireless communication system to which embodiments are applied may be a coordinated multi-point transmission / reception system (CoMP system) or a coordinated multi-antenna transmission scheme in which two or more transmission / reception points cooperate to transmit a signal. antenna transmission system), a cooperative multi-cell communication system. The CoMP system may include at least two multiple transmission / reception points and terminals.

The multiple transmit / receive point is at least one having a base station or a macro cell (hereinafter referred to as an eNB) and a high transmission power or a low transmission power in a macro cell region, which is wired controlled by an optical cable or an optical fiber to the eNB. May be RRH.

In the following, downlink refers to a communication or communication path from a multiple transmission / reception point to a terminal, and uplink refers to a communication or communication path from a terminal to multiple transmission / reception points. In downlink, a transmitter may be part of multiple transmission / reception points, and a receiver may be part of a terminal. In uplink, a transmitter may be part of a terminal, and a receiver may be part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted and received through a channel such as a PUCCH, a PUSCH, a PDCCH, an EPDCCH, and a PDSCH may be expressed in the form of 'sending and receiving a PUCCH, a PUSCH, a PDCCH, an EPDCCH, and a PDSCH.'

In addition, hereinafter, a description of transmitting or receiving a PDCCH or transmitting or receiving a signal through the PDCCH may be used as a meaning including transmitting or receiving an EPDCCH or transmitting or receiving a signal through the EPDCCH.

That is, the physical downlink control channel described below may mean PDCCH or EPDCCH, and may also be used to include both PDCCH and EPDCCH.

In addition, for convenience of description, the EPDCCH, which is an embodiment of the present invention, may be applied to the portion described as the PDCCH, and the EPDCCH may be applied to the portion described as the EPDCCH as an embodiment of the present invention.

Meanwhile, high layer signaling described below includes RRC signaling for transmitting RRC information including an RRC parameter.

The eNB performs downlink transmission to the terminals. The eNB includes downlink control information and an uplink data channel (eg, a physical downlink shared channel (PDSCH), which is a primary physical channel for unicast transmission, and scheduling required to receive the PDSCH. For example, a physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission on a physical uplink shared channel (PUSCH) may be transmitted. Hereinafter, the transmission and reception of signals through each channel will be described in the form of transmission and reception of the corresponding channel.

In this specification, a frequency band not exclusively used by a specific communication system or a specific operator is described as an unlicensed band frequency or an unlicensed band. For example, when a wireless LAN communication system such as Wi-Fi and a mobile communication system share and use the same frequency band, the corresponding frequency band is described as an unlicensed band frequency. In addition, hereinafter, the mobile communication system will be described using LTE or LTE-Advanced as an example.

In addition, a cell using an unlicensed band frequency in a mobile communication system is described as an unlicensed band cell.

Recently, 3GPP has been discussing how to use the unlicensed frequency band as a way to cope with the explosion of mobile data traffic. Unlicensed bands are of lower quality than licensed bands, but they are expected to provide sufficient value to operators with limited bandwidth by utilizing the unlicensed bands by complementing the licensed bands.

The use of unlicensed bands in LTE requires addressing a number of regional regulations and technical limitations. For example, multiple technologies must be able to be used fairly in the unlicensed band. LTE and WiFi technologies, for example, must be able to be used fairly. For this purpose, a technology that can be used fairly by coexistence (coexistence) in the E-UTRAN must be provided. However, there is currently no technology for this in LTE. As another example, multiple operators should be able to use unlicensed bands. To this end, E-UTRAN must provide a technology that can be used fairly by co-existence of multiple operators in the unlicensed band, but there is currently no technology for this in LTE.

1 is a view for explaining the ETSI LBT related standards.

One of the limitations required to utilize unlicensed bands is the List before Talk (LBT) requirement. In Europe and Japan, regulations for the use of unlicensed bands should be checked to see if there is another share in the channel before the talk. For example, according to the LBT requirement (e.g., ETSI EN 301 893) for frame-based equipment defined by ETSI (e.g., equipment having a structure with a fixed timing for transmitting and receiving structures), the UE or AP When an access point wants to transmit, an energy detect should be performed during a listening time called a Clear Channel Assessment (CCA) cycle. The listening time may be set to 20 us or more. If the energy level exceeds the CCA threshold, the UE or the AP should not transmit on the channel during the next fixed frame period considering that the channel is occupied. If the channel is clear (for example, if the energy level is lower than the CCA threshold), the equipment can transmit during the channel occupancy time. The total time the equipment can transmit on a given channel without reassessing the channel's availability is called the channel occupancy time. The channel occupancy time should be in the range of 1 ms to 10 ms.

The minimum idle period should be at least 5% of the channel occupancy time used by the equipment during the current fixed frame period. If the equipment wants to continue the transmission, the CCA process must be repeated.

Uplink Data Transfer

In order to transmit on the UL-SCH, the UE must have a valid uplink grant that is dynamically configured on the PDCCH or received within a random access response or configured semi-persistently. However, this may not be the case when non-adaptive HARQ retransmission is performed.

The terminal delivers HARQ information associated with an uplink grant to an HARQ entity.

The terminal has a respective HARQ entity for each serving cell with uplink. The HARQ entity has a parallel HARQ process that allows for continuous transmission while waiting for HARQ feedback for successful or failed reception of previous transmissions. In this specification, the HARQ process may mean a processor configured in a HARQ entity to perform an operation for continuously transmitting or an independent individual procedure for performing a specific operation in order.

If an uplink grant is indicated for a given TTI, the HARQ entity identifies the HARQ process in which the transmission will occur. The HARQ entity also routes HARQ feedback, MCS and resources carried by the physical layer to the appropriate HARQ process.

The HARQ entity identifies the HARQ process associated with each TTI and, if an uplink grant is indicated for each identified HARQ process, obtains a MAC PDU from the "Multiplexing and assembly" entity, MAC PDU, uplink grant and Deliver HARQ information to the identified HARQ process and instruct the identified HARQ process to trigger transmission.

Once TTI bundling is configured, the same HARQ process is invoked for each transmission that is part of the same bundle. HARQ retransmission within one bundle is non-adaptive. It is triggered without waiting for feedback from a previous transmission according to the TTI bundle size (TTI_BUNDLE_SIZE). The HARQ feedback of the bundle is only received for the last TTI of the bundle. Retransmission of a TTI bundle is likewise a TTI bundle. TTI bundling is not supported if the terminal (or MAC entity) is configured with at least one SCells with uplink.

For the uplink grant reception and the HARQ operation through the UL-SCH, refer to detailed procedures in Sections 5.4.1 and 5.4.2 of 3GPP TS 36.321, respectively.

Uplink HARQ Transmit / Retransmit

FIG. 2 is a diagram for describing an uplink HARQ operation.

Uplink HARQ in E-UTRAN has the following characteristics.

The timing relationship between uplink data transmission and HARQ feedback is fixed. For example, in the FDD mode, uplink data transmission in the nth subframe causes PHICH transmission in the n + 4 subframe. For another example, in the TDD mode, the timing relationship varies according to downlink-uplink allocation. In the TDD mode, uplink data transmission in the nth subframe causes PHICH transmission in the n + k (k is 4 or more) subframe. Here n + k represents an uplink subframe in which Acknowledgment is to be transmitted from the UE.

The timing relationship between uplink grant reception and uplink data transmission is fixed. For example, in the case of FDD, when the UE detects PDCCH / EPDCCH and / or PHICH transmission having DCI format 0/4 in the nth subframe, the corresponding PUSCH in the n + 4 subframe according to the PDCCH / EPDCCH and PHICH information. (For FDD and normal HARQ operation, the UE shall upon detection on a given serving cell of a PDCCH / EPDCCH with DCI format 0/4 and / or a PHICH transmission in subframe n intended for the UE, adjust the corresponding PUSCH transmission in subframe n + 4 according to the PDCCH / EPDCCH and PHICH information). For example, if the UE detects PDCCH / EPDCCH and / or PHICH transmission having the uplink DCI format in the nth subframe with respect to TDD UL / DL configuration 1-6, n + k sub according to the PDCCH / EPDCCH and PHICH information. Adjust the corresponding PUSCH in the frame. Where k is provided in Table 8-2 of 3GPP document TS36.213 (For TDD UL / DL configurations 1-6 and normal HARQ operation, the UE shall upon detection of a PDCCH / EPDCCH with uplink DCI format and / or a PHICH transmission in subframe n intended for the UE, adjust the corresponding PUSCH transmission in subframe n + k, with k given in Table 8-2 in TS36.213, according to the PDCCH / EPDCCH and PHICH information).

synchronous HARQ: Retransmission for each HARQ process occurs at a predefined time for the initial transmission. For example, if uplink data transmission of the nth subframe is not successfully received, retransmission is required for n + 8 subframes for the FDD.

The maximum number of retransmissions may be configured for each terminal.

Downlink ACK / NACK for uplink (re) transmission can be sent over PHICH.

1) If the PDCCH for the UE is correctly received regardless of the contents of the HARQ feedback (ACK or NACK), the UE follows the request of the PDCCH to the UE. That is, the terminal performs transmission or retransmission. (Regardless of the content of the HARQ feedback (ACK or NACK), when a PDCCH for the UE is correctly received, the UE follows what the PDCCH asks the UE to do i.e.perform a transmission or a retransmission (referred to as adaptive retransmission)

2) When the PDCCH addressing the C-RNTI of the UE is not detected, HARQ feedback indicates whether the UE performs retransmission. (When no PDCCH addressed to the C-RNTI of the UE is detected, the HARQ feedback dictates how the UE performs retransmissions:

NACK: the UE performs a non-adaptive retransmission i.e. a retransmission on the same uplink resource as previously used by the same process;

ACK: the UE does not perform any UL (re) transmission and keeps the data in the HARQ buffer. A PDCCH is then required to perform a retransmission i.e. a non-adaptive retransmission cannot follow.)

As described above, the conventional E-UTRAN does not provide a function for satisfying the LBT requirement of the unlicensed band. Therefore, uplink data could not be transmitted by combining LBT operations in the terminal. In particular, in the E-UTRAN, the UE performs uplink transmission after a predetermined (processing) time after receiving an uplink grant from the base station. Therefore, when the unlicensed band is to be used in the E-UTRAN, even if the UE receives an uplink grant from the base station, it is necessary to perform LBT before the uplink transmission. Accordingly, the terminal should detect whether the radio link is available for a certain period of time, and stop the uplink data transmission when the use of the radio link is detected. However, E-UTRAN did not provide this behavior.

In addition, since E-UTRAN is based on synchronous HARQ retransmission, there is a problem that a failure of uplink data transmission / retransmission may cause a delay of a certain time. According to the synchronous HARQ retransmission, if the UE fails to transmit, even if the time to perform retransmission (subframe) falls within an unavailable interval (eg, an idle period or an unavailable time or gap), the UE may perform non-adaptive retransmission. There was a problem that could be done.

As described above, the terminal of the present invention may perform radio link detection, channel occupancy detection, collision detection, or energy detection during a detection time, a detection time, or a listening time to perform an LBT operation. For example, the terminal may determine whether the energy level of the corresponding band exceeds a specific threshold for energy detection.

Hereinafter, for convenience of understanding, it is described that energy detection is performed for a predetermined time with respect to the LBT operation of the aforementioned terminal. This description is meant to include the above-described detection time or detection time or listening time, respectively, and should be understood to include both radio link detection channel occupancy detection or collision detection. That is, the following briefly describes an operation of performing energy detection for a predetermined time, but is not limited thereto.

The present invention devised to solve this problem is to provide an uplink data transmission / retransmission method that satisfies the LBT constraint. In addition, an object of the present invention is to provide a method for effectively retransmitting uplink data when the terminal fails to perform uplink transmission / retransmission due to LBT.

As an example of a scenario in which an unlicensed frequency band may be used based on LTE, a case where a small cell is used in an indoor or outdoor hot spot established by an individual operator may be considered.

For example, Release 10 or Release 11 Carrier Aggregation (CA) technology based on a single base station may be used. When the CA technology is used, the primary cell may use the licensed band frequency, and the unlicensed frequency band may be used for the merged secondary cell.

For another example, two base station-based Release 12 Dual Connectivity technology can be used. When dual connectivity technology is used, one or more cells of the master base station cell group or the primary cell in the master base station cell group or the master base station cell group may use the licensed band frequency. One or more cells of the secondary base station cell group or the secondary base station cell group may use an unlicensed band frequency.

3 is a diagram illustrating an example of unlicensed band cell merging to which the present invention can be applied.

3, an unlicensed band cell may be used for downlink transmission only or may be used for both uplink and downlink transmission.

For example, when using the aforementioned LTE technology, CA technology, or dual connectivity technology, one or more unlicensed band cells using an unlicensed frequency band may be configured to transmit data through the unlicensed band. In this case, the unlicensed band cell may be used for downlink only. Or an unlicensed band cell can be used for uplink and downlink data transmission.

The base station and the terminal of the present invention can be applied to various embodiments as follows to effectively perform LBT-based uplink data transmission / retransmission. Each embodiment described below may be used independently, or may be used in combination with each other.

4 is a view for explaining the operation of the terminal according to an embodiment of the present invention.

A terminal according to another embodiment of the present invention comprises the steps of configuring a carrier aggregation including an unlicensed band cell using a frequency shared by one or more communication systems and receiving scheduling information for uplink transmission in the unlicensed band cell And determining whether the unlicensed band cell is an available interval and transmitting uplink data based on scheduling information if the unlicensed band cell is an available interval.

Referring to FIG. 4, the terminal of the present invention includes a step of configuring carrier aggregation including an unlicensed band cell using a frequency shared by one or more communication systems (S410). For example, the terminal may configure carrier aggregation using the licensed band cell and the unlicensed band cell according to the configuration of the base station. In this case, the terminal may receive configuration information necessary for configuring carrier aggregation from the base station. The terminal may transmit / receive data with the base station using the configured licensed band cell and unlicensed band cell. As mentioned above, the unlicensed band cell may be set to uplink or downlink.

In addition, the terminal of the present invention includes the step of receiving scheduling information for uplink transmission in the unlicensed band cell (S420). For example, the terminal may receive scheduling information for uplink data transmission in the unlicensed band cell from the base station. The scheduling information includes uplink grant information.

In addition, the terminal of the present invention includes the step of determining whether the unlicensed band cell is available interval (S430). As described above, the terminal may determine whether the radio link or the radio channel of the unlicensed band cell is available. To this end, the terminal may check whether energy detection or radio link occupancy / collision for the corresponding unlicensed band cell. That is, the terminal may perform the same operation as the radio link energy detection in the above-described LBT procedure.

In addition, when the unlicensed band cell is an available period, the present invention includes transmitting uplink data based on the scheduling information (S440). For example, the terminal may or may not transmit uplink data through the unlicensed band cell according to the determination result of step S530.

For example, when the UE is an unlicensed band cell available interval, a hybrid automatic repeat request (HARQ) entity of the terminal is a HARQ process for performing uplink data transmission, Medium Access Control (MAC) Protocol Data Unit (PDU), up One or more of a link grant (UL grant) and HARQ information may be carried. Through this, the terminal may transmit uplink data to the base station in the corresponding unlicensed band cell.

As another example, when the unlicensed band cell is an unusable period, the terminal may transmit uplink data when the unlicensed band cell becomes an available period through an asynchronous retransmission procedure.

As another example, when the unlicensed band cell is an unavailable period, the terminal may determine whether the next transmission time interval (TTI) is an available interval, and may transmit uplink data when the unlicensed band cell becomes an available interval. Here, the maximum value of the next TTI may be set by the base station.

In the following description, embodiments in which a UE determines availability of an unlicensed band cell before uplink data transmission are divided and described, and each embodiment may be applied independently or in combination with each other.

Example 1: After performing an LBT after instructing the HARQ process to generate a transmission to the physical layer

5 is a diagram illustrating an uplink data transmission processing procedure of a terminal according to another embodiment of the present invention.

The present invention may instruct the HARQ process to generate a transmission to the physical layer, and then perform LBT.

Referring to FIG. 5, the terminal delivers HARQ information associated with an uplink grant or uplink grant received at the physical layer to the HARQ entity or the MAC layer (S510).

For example, in a situation in which the UE has a C-RNTI, the UE has a TTL, a serving cell to which the TAG in which the timeAlignmentTimer operates, and each grant received in the TTI has an uplink grant for the corresponding TTI and the serving cell. When received on the PDCCH for the C-RNTI that the terminal has, it may transmit HARQ information associated with the uplink grant to the HARQ entity. Alternatively, when the uplink grant for the corresponding TTI is received through a random access response, the terminal may transmit HARQ information associated with the uplink grant to the HARQ entity.

The terminal transmits a MAC PDU to be transmitted with the uplink grant or the uplink grant associated with the uplink grant indicated for the TTI to the given TTI through the HARQ entity to the HARQ process to generate a transmission to the corresponding TTI (S520). In addition, the UE instructs that the HARQ process identified through the HARQ entity triggers a new transmission or generates an adaptive retransmission (S520). If the uplink grant is not indicated for the corresponding HARQ process and the corresponding TTI and the HARQ buffer is not empty, the identified HARQ process may instruct to generate non-adaptive retransmission.

For example, for a given TTI, if an uplink grant is indicated for that TTI, the HARQ entity identifies the HARQ process for which the transmission will occur. In case of using Asynchronous HARQ retransmission for the unlicensed band cell, the HARQ process can be identified through the HARQ process ID included in the received HARQ information. In case of using synchronous HARQ retransmission, the HARQ process can be identified based on timing information. Can be. In addition, the HARQ entity routes the received HARQ feedback, MCS and resources to the appropriate HARQ process.

For each TTI, the HARQ entity identifies the HARQ process associated with that TTI. For each identified HARQ process, the HARQ entity obtains a MAC PDU to be transmitted from the "Multiplexing and assembly" entity when certain conditions are satisfied, and delivers the MAC PDU, uplink grant, and HARQ information to the identified HARQ process. . In addition, the HARQ entity instructs the identified HARQ process to trigger the transmission. Here, the specific condition is that when an uplink grant is indicated to the corresponding HARQ process and the corresponding TTI, when the received grant is provided with the NDI toggled relative to the value for the previous transmission of this HARQ process, the associated HARQ information, or It may be one of the cases where the HARQ buffer received and identified on the PDCCH for that C-RNTI is empty.

The HARQ process instructs to generate the transmission according to the uplink grant stored with the current redundancy version to the physical layer in order to generate the uplink transmission (S530). The HARQ process increases the current redundancy version by 1 (S540).

Hereinafter, the operations of steps S510 to S540 will be described in more detail.

Each HARQ process is associated with one HARQ buffer. Each HARQ process maintains a 'CURRENT_TX_NB' state variable indicating the number of transmissions to occur for the MAC PDU of the current buffer and a 'HARQ_FEEDBACK' state variable indicating the HARQ feedback for the MAC PDU of the current buffer. The order of the redundancy version is 0, 2, 3, 1. The variable 'CURRENT_IRV' is an index in redundancy version order.

The new transmission is performed with the MCS indicated on the PDCCH on the resource. Adaptive transmission is performed with the MCS indicated on the PDCCH on the resource. If non-adaptive transmission is used, non-adaptive transmission is performed with the same MCS that was used for previously made transmission attempts on the same resource.

The terminal is configured with the maximum number of HARQ transmission information. Alternatively, the terminal is configured with maximum timer information for HARQ transmission.

If the HARQ entity requests a new transmission, the HARQ process sets the 'CURRENT_TX_NB' to 0, sets the 'CURRENT_IRV' to 0, stores the MAC PDU in the associated HARQ buffer, received from the HARQ entity. At least one of an operation of storing an uplink grant and an operation of setting 'HARQ_FEEDBACK' to NACK is performed, and a transmission described below is generated.

If the HARQ entity requests retransmission, the HARQ process performs an operation of incrementing 'CURRENT_TX_NB' by 1 and generates a transmission described below. If the HARQ entity requests adaptive retransmission, storing the uplink grant received from the HARQ entity, setting 'CURRENT_IRV' to an index corresponding to the redundancy version value provided in the HARQ information, and 'HARQ_FEEDBACK' to NACK. Perform at least one of the setting operations, and generate a transmission as described below. Otherwise, if the HARQ request requested non-adaptive retransmission, the transmission described below is generated when 'HARQ_FEEDBACK' is NACK.

In order to generate a transmission, the HARQ process does not have a measurement gap at that transmission time, and in the case of retransmission, if the retransmission does not collide with the transmission for the MAC PDU obtained from the Msg3 buffer at this TTI, the 'CURRENT_IRV' at the physical layer. Instructs to generate a transmission according to the stored uplink grant with a redundancy version corresponding to the value, and increments 'CURRENT_IRV' by one.

Hereinafter, the operation after the above-described step S540 will be described.

In a cell using an unlicensed frequency band, the terminal or the physical layer detects or detects a radio link for a predetermined time (S550). Alternatively, the MAC layer (eg, HARQ entity or HARQ process) may perform step S550.

If the occupancy or collision is detected on the radio link or the energy level exceeds a certain threshold value, the terminal does not perform uplink transmission to the corresponding TTI (S560). For example, the physical layer does not perform the indicated transmission.

If the occupancy or collision is not detected on the radio link or if the energy level is lower than a specific threshold value, the terminal performs uplink transmission to the corresponding TTI (S570).

As described with reference to FIG. 1, according to the LBT requirement for frame-based equipment, a terminal may have a channel occupancy time in a range of 1 ms to 10 ms that can be transmitted on a given channel without re-evaluating channel availability.

For example, the base station does not re-evaluate the availability of the radio link when the terminal succeeds in evaluating the availability of the radio link for uplink transmission or when the radio link energy is detected and no occupancy or collision is detected on the radio link. A transmission time for performing link transmission may be configured in the terminal or related information may be provided to the terminal.

As another example, the base station may configure a transmission time for the terminal to perform the uplink transmission without re-evaluating the availability of the radio link, or may provide related information to the terminal.

As another example, the base station may allow to re-evaluate the availability of the radio link at every uplink transmission time.

If the base station provides the aforementioned transmission time or related information to the terminal, the terminal may configure a state variable for checking whether to perform radio link energy detection in the unlicensed band cell. For example, the terminal sets the aforementioned state variable to 0 in the TTI to perform initial uplink transmission of the unlicensed band cell. If the occupancy or collision is not detected on the radio link in the radio link energy detection for the TTI to perform the initial uplink transmission, or if the energy level does not exceed a certain threshold value, the state variable according to the TTI elapsed by the TTI configured in the base station. To increase. If an occupancy or collision is detected on the radio link in the radio link energy sensing for the TTI to perform the initial uplink transmission, or if the energy level exceeds a certain threshold, the state variable is reset to zero at the next TTI. When the state variable is set to 0, radio link energy sensing is performed. For example, when the state variable is set to 0, the radio link energy sensing step is performed as in the embodiments included in the present invention.

In the unlicensed band cell, the terminal may not be able to transmit the uplink at the actual uplink time even when the terminal receives the uplink grant according to the LBT requirement or the maximum channel occupancy requirement. As described above, when the terminal receives the uplink grant and stores the MAC PDU in the HARQ buffer to trigger a new transmission, a delay may occur in the transmission of the MAC PDU.

Example 2 Method 1 Instructs HARQ Process to Generate Transmission to Physical Layer After Checking Energy Detection

6 is a diagram for explaining an uplink data transmission processing procedure according to another embodiment of the present invention.

The operation of each step will be described in detail with reference to FIG. 6.

The physical layer of the terminal transmits the HARQ information associated with the received uplink grant or uplink grant to the HARQ entity or MAC layer (S610). For example, in a situation in which the UE has a C-RNTI, the UE has a TTL, a serving cell to which the TAG in which the timeAlignmentTimer operates, and each grant received in the TTI has an uplink grant for the corresponding TTI and the serving cell. When received on the PDCCH for the C-RNTI that the terminal has, it may transmit HARQ information associated with the uplink grant to the HARQ entity. Alternatively, when the uplink grant for the corresponding TTI is received through a random access response, the terminal may transmit HARQ information associated with the uplink grant to the HARQ entity.

The terminal transmits a MAC PDU to be transmitted with the uplink grant or the uplink grant associated with the uplink grant indicated for the TTI to the given TTI through the HARQ entity to the HARQ process to generate a transmission to the corresponding TTI (S620). In addition, the UE instructs the HARQ process identified through the HARQ entity to trigger a new transmission or generate an adaptive retransmission (S620). If the uplink grant is not indicated for the corresponding HARQ process and the corresponding TTI and the HARQ buffer is not empty, the identified HARQ process may instruct to generate non-adaptive retransmission.

For example, for a given TTI, if an uplink grant is indicated for that TTI, the HARQ entity identifies the HARQ process for which the transmission will occur. In case of using Asynchronous HARQ retransmission for the unlicensed band cell, the HARQ process can be identified through the HARQ process ID included in the received HARQ information. In case of using synchronous HARQ retransmission, the HARQ process can be identified based on the timing information. Can be. In addition, the HARQ entity routes the received HARQ feedback, MCS and resources to the appropriate HARQ process.

For each TTI, the HARQ entity identifies the HARQ process associated with that TTI. For each identified HARQ process, the HARQ entity obtains a MAC PDU to be transmitted from the "Multiplexing and assembly" entity when certain conditions are satisfied, and delivers the MAC PDU, uplink grant, and HARQ information to the identified HARQ process. . In addition, the HARQ entity instructs the identified HARQ process to trigger the transmission. Here, the specific condition is that when an uplink grant is indicated to the corresponding HARQ process and the corresponding TTI, when the received grant is provided with the NDI toggled relative to the value for the previous transmission of this HARQ process, the associated HARQ information, or It may be one of the cases where the HARQ buffer received and identified on the PDCCH for that C-RNTI is empty.

Meanwhile, in the present embodiment, the terminal may additionally instruct the radio link energy detection of the unlicensed band cell in step S620. Alternatively, the terminal may instruct radio link energy detection of the unlicensed band cell before step S620. For example, radio link energy detection of an unlicensed band cell may be performed before step S610 or step S610 or between steps S610 and S620.

For example, the terminal may detect the occupancy / collision of the corresponding radio link through the radio link energy detection of the unlicensed band cell (S630).

If the occupancy is detected on the wireless link or if the energy level exceeds a certain threshold value, the terminal does not perform uplink transmission (S640). That is, the procedure may be terminated without performing uplink transmission for the corresponding uplink grant. In this case, for the received uplink grant, the corresponding MAC PDU is not stored in the HARQ buffer to trigger a new transmission. Or, in this case, the MAC PDU obtained from the "Multiplexing and assembly" entity is returned. Or, in this case, do not acquire the MAC PDU to send from the "Multiplexing and assembly" entity. In this way, MAC PDUs not used for new transmissions at the corresponding uplink transmission time can be quickly transmitted to the next transmission opportunity.

If the occupancy / collision is not detected on the wireless link or the energy level does not exceed a certain threshold, the terminal performs uplink transmission. That is, when the radio link energy detection indication for the unlicensed band cell is performed before step S620, for each TTI, the HARQ entity identifies the HARQ process associated with the TTI, and for the identified HARQ process, the " Multiplexing and assembly " entity. The MAC PDU can be obtained from the UE, the uplink grant and the MAC PDU can be transmitted to the HARQ process, and the transmission / retransmission generation can be instructed. In addition, the terminal may instruct the transmission to the physical layer (S650). If necessary, an operation of increasing the redundancy version may be performed (S660). Through this, the terminal performs a physical layer transmission step.

Referring to step S630 in detail, the terminal or the physical layer in the cell using the unlicensed frequency band detects or detects the radio link for a predetermined time (S630). Or the MAC layer (eg, HARQ entity or HARQ process) may perform step S630.

As described above, if the occupancy / collision is detected on the radio link or the energy level exceeds a certain threshold, the terminal may not perform the uplink transmission (S640). In this case, the redundancy version (or 'CURRENT_IRV') can be maintained.

As another example, the HARQ process may set HARQ feedback to ACK. Or, the HARQ process may set HARQ feedback ('HARQ_FEEDBACK') to ACK at the time of detecting the occupancy / collision on the radio link for the transmission. If the non-adaptive retransmission is performed, the UE may perform non-adaptive transmission for the uplink transmission that did not perform the uplink transmission on the next transmission opportunity (for example, the n + 8th subframe). To this end, the HARQ process may maintain a state variable indicating that occupancy / collision is detected on the wireless link or that the energy level has not performed an uplink transmission above a certain threshold.

If the occupancy / collision is not detected on the wireless link or if the energy level is lower than a specific threshold value, the terminal may perform uplink transmission. For example, the HARQ entity identifies the HARQ process associated with the corresponding TTI and, for the identified HARQ process, obtains a MAC PDU to send from the "Multiplexing and assembly" entity, forwards the uplink grant and the MAC PDU to the HARQ process and transmits / The retransmission can be instructed. As another example, in order to generate the uplink transmission, the HARQ process may instruct the physical layer to generate the transmission according to the uplink grant stored with the current redundancy version (S650). If the non-adaptive retransmission is performed, the HARQ process may increase the current redundancy version by 1 (S660). As another example, to generate an uplink transmission, the HARQ process may collide with the transmission for the MAC PDU obtained from the Msg3 buffer in this TTI if no measurement gap exists at the time of that uplink transmission, and in the case of retransmission. If no occupancy / collision is detected on the wireless link, the physical layer is instructed to generate a transmission according to the stored uplink grant with a redundancy version corresponding to the value of 'CURRENT_IRV', and if not, performs non-adaptive retransmission. If it is, increase the 'CURRENT_IRV' by 1.

Meanwhile, if the UE cannot receive the HARQ feedback due to the LBT of the UE or the base station at the HARQ feedback reception time for the uplink transmission, the UE may perform HARQ feedback ('HARQ_FEEDBACK') at the HARQ feedback reception time for the corresponding uplink transmission. Can be set to ACK. Through this, when the base station successfully receives the uplink transmission of the terminal, it is possible to prevent the terminal from repeatedly retransmitting the uplink transmission. That is, even if the UE does not receive the HARQ feedback for the uplink transmission transmitted in the nth subframe, the retransmission operation for the corresponding uplink transmission in the n + 8th subframe may not be performed. In other words, it is possible to avoid performing synchronized non-adaptive retransmission by the uplink HARQ prior art for the unlicensed band cell. If the base station fails to receive the uplink transmission of the terminal, the base station may perform adaptive retransmission through the uplink grant. That is, it is possible to perform asynchronous adaptive retransmission through the uplink grant for the unlicensed band cell. In other words, the adaptive retransmission may be performed at another time without performing the retransmission at the time for performing the retransmission (for example, the n + 8th subframe). For example, adaptive retransmission may be performed at a time (eg, n + 16th subframe) to perform the next retransmission. As another example, an asynchronous adaptive retransmission may be performed at any time after the base station recognizes this uplink transmission reception failure.

Example 3 Method 2 Instructs HARQ Process to Generate Transmission to Physical Layer After Checking Energy Detection

7 is a diagram for explaining an uplink data transmission processing procedure according to another embodiment of the present invention.

 Referring to FIG. 7, in the present embodiment, the terminal performs an operation similar to the steps of FIGS. 5 and 6 described above. That is, the steps S710 to S730 and the steps S750 and S760 are the same as the operations of the uplink grant delivery, transmission / retransmission generation instruction, occupancy / collision check, physical layer transmission indication, and redundancy version increment operation of FIGS. 5 and 6. .

However, in the present embodiment, there is a difference in that a redundancy version is increased when the occupancy / collision is detected on the radio link or the energy level exceeds a specific threshold so that the terminal does not perform the uplink transmission. (S740). Therefore, hereinafter, the differences will be described based on the differences, and the other steps may be equally applied to the contents described with reference to FIGS. 5 and 6.

The base station knows when the terminal fails to perform uplink transmission according to the LBT requirement, or when the terminal detects an occupancy / collision on the radio link or when the energy level does not perform the uplink transmission above a certain threshold. You may or may not know.

If the base station can know that the uplink transmission of the terminal is not performed, it may be better for the terminal and the base station to maintain the redundancy version (or 'CURRENT_IRV'). Or, even if the base station does not know that the uplink transmission is not performed, it may be better for the terminal and the base station to maintain the redundancy version (or 'CURRENT_IRV').

In the case of uplink HARQ transmission which performs non-adaptive retransmission of the prior art, the terminal applies a specific redundancy version order whenever retransmission is performed. For example, redundancy version 0 for new transmissions, redundancy version 2 for the first retransmission, redundancy version 3 for the second retransmission, and redundancy version 1 for the third retransmission. In this way, the terminal and the base station perform encoding and decoding by using the redundancy version for the transmission. The terminal determines the redundancy version to be applied to the next retransmission using 'CURRENT_IRV'. If the UE increases the redundancy version without performing the uplink transmission, some of the above-described redundancy version may be omitted and transmission may cause performance degradation. In particular, a small cell environment in which CA or dual connectivity is used may typically be a case where the terminal speed is low and the number of terminals handled by the base station is small, so it may be undesirable to use some of the redundancy versions to use the next redundancy version. .

Accordingly, when the terminal does not perform the uplink transmission, it may be desirable to maintain the redundancy version (or 'CURRENT_IRV') as it is, as shown in the embodiment of FIG. 5. For example, the base station may know that the terminal did not perform the uplink transmission in the idle period or the unavailable time, which will be described below. In this case, the base station may maintain the redundancy version (or 'CURRENT_IRV') without increasing it. As another example, the base station knows that the UE did not perform the uplink transmission by confirming that the next redundancy version is used as the previous transmission / retransmission for the (next) retransmission and thus does not increase the redundancy version (or 'CURRENT_IRV'). You can keep it. As another example, the base station includes information indicating the occupancy / collision detection on the radio link in the scheduling information, or receives information indicating that the uplink transmission was not performed due to the LBT at the corresponding transmission / retransmission time from the terminal. By doing so, it may be known that the terminal has not performed the uplink transmission. As another example, the UE may transmit information indicating that uplink transmission has not been performed due to LBT to the base station through a PCell or another licensed band cell.

As described above, when the terminal does not perform the uplink transmission for the uplink grant, the base station may maintain without increasing the redundancy version when the base station can know that the uplink is not transmitted.

However, if the base station does not know that the uplink transmission is not performed according to the LBT operation of the terminal, an additional processing procedure may be required. Since the UE and the base station must perform encoding and decoding using the same redundancy version, it may be necessary to match the order of the redundancy versions according to the transmission / retransmission order. Thus, even if no occupancy / collision is detected on the wireless link or the uplink transmission is not performed when the energy level exceeds a certain threshold, increasing the redundancy version (or increasing 'CURRENT_IRV' by 1) may be allowed. Through this, when the transmission or the random retransmission fails due to the LBT, the terminal and the base station can be processed with the same redundancy version at the next transmission opportunity.

What to do when HARQ transmission / retransmission occurs in idle period or unavailable time

8 is a diagram illustrating a section of an unlicensed band cell of the present invention.

As mentioned above, the LBT requirement for frame based equipment requires that the minimum Idle Period should be at least 5% of the channel occupancy time used by the equipment during the current fixed frame period. Therefore, if the UE occupies and uses a certain time channel, it should not perform transmission for another predetermined time after that (for example, 1 ms). Similarly, when an operator uses an unlicensed frequency band, there may be an unavailable time / unavailable gap for coexistence with other technologies or with other operators.

Referring to FIG. 8, in the present invention, for the convenience of description, any operator may configure an unlicensed band cell in a frequency band of an unlicensed spectrum to support LTE or LTE-Advanced terminal of the corresponding operator. A time period is called an available period of an unlicensed band cell. In addition, a time period in which a corresponding unlicensed band cell cannot be configured or used is referred to as an unavailable period. However, this is also for convenience of description and the name is not limited.

Information related to the available interval of the unlicensed band cell for the terminal may be indicated by the base station. As an example, the base station may indicate the start time and duration of the available interval through a licensed band cell such as a PCell of the terminal. As another example, the base station may configure or pre-set the start time or period of the available interval through the licensed band cell or the unlicensed band cell of the terminal through an RRC message, MAC CE, PDCCH, or the like.

As described above, the uplink HARQ according to the prior art in the E-UTRAN is based on synchronous HARQ retransmission. For example, if uplink data transmission of the nth subframe is not successfully received, retransmission is required for n + 8 subframes for the FDD. Specifically, for each TTI, the HARQ entity identifies the HARQ process associated with the TTI. And for each identified HARQ process, if the uplink grant is not indicated to the corresponding HARQ process and the corresponding TTI, and if the HARQ buffer of the corresponding HARQ process is not empty, then the identified HARQ process is non-adaptive. May instruct to generate a retransmission.

 That is, even if the terminal does not receive an explicit uplink grant for uplink retransmission to the base station, it may perform non-adaptive retransmission if the HARQ buffer of the HARQ process is not empty. Since the HARQ buffer stores the MAC PDU when the HARQ entity requests a new transmission and is flushed when the MAC is reset or the maximum number of HARQ transmissions is reached, non-adaptive retransmission may be performed when the transmission fails.

Hereinafter, the processing method of the present invention will be described in detail when HARQ transmission or retransmission occurs.

The specific idle period or unavailable period may be known to both the terminal and the base station. On the other hand, another particular idle period or unavailable period may be known only to the terminal.

If, after the UE fails to transmit (for example, the nth subframe), the time for performing retransmission (for example, the n + 8th subframe) corresponds to an idle period or an unavailable period, the HARQ entity The identified HARQ process may indicate not to generate non-adaptive retransmissions.

Alternatively, if the UE fails to transmit, and the time to perform retransmission corresponds to an idle period or an unavailable period, the HARQ process may not instruct the physical layer to generate a transmission.

Alternatively, if the UE fails to transmit, the time for performing retransmission corresponds to an idle period or an unavailable period, the UL-SCH transmission may not be performed. That is, according to the LBT requirement or the maximum channel occupancy requirement, the synchronized non-adaptive retransmission of the uplink HARQ according to the prior art may not be performed in the unlicensed band cell.

As another method, if the time to perform retransmission after the terminal fails in transmission corresponds to an idle period or an unavailable period, the HARQ entity may instruct the identified HARQ process not to generate non-adaptive retransmission. The terminal may transmit information indicating that uplink transmission has not been performed due to an idle period or an unavailable period to a base station through a PCell or another licensed band cell. Through this, the base station may obtain information on a specific idle period or unavailable period that only the terminal knows. In addition, through this, the terminal and the base station may maintain the same redundancy version at the retransmission opportunity.

In another method, when uplink retransmission or uplink transmission or UL-SCH transmission cannot be performed due to an idle period or an unavailable period generation, HARQ feedback cannot be received. And non-adaptive retransmission may occur continuously. For example, if an uplink transmission or retransmission cannot be performed because the time of any transmission or retransmission overlaps with an idle period or an unavailable period, if the base station knows information about the idle period or the unavailable period, it is unnecessary. Transmission of HARQ feedback may be restricted. However, even in this case, since the UE has the MAC PDU in the HARQ buffer and the HARQ feedback is set to NACK, the UE may perform retransmission in the next retransmission subframe.

Alternatively, if the HARQ feedback reception time for any uplink transmission overlaps with an idle period or an unavailable period, the terminal ACKs HARQ feedback ('HARQ_FEEDBACK') at the HARQ feedback reception time for the corresponding uplink transmission. Can be set. Through this, when the base station successfully receives the uplink transmission of the terminal, it is possible to prevent the retransmission of unnecessary uplink transmission of the terminal. If the base station does not receive the uplink transmission of the terminal, it may be to perform the adaptive retransmission through the uplink grant. That is, by setting the HARQ feedback value to ACK, the terminal may perform adaptive retransmission at different times according to the uplink grant without performing retransmission at the time for retransmission. As an example of the adaptive retransmission time, the UE may perform adaptive retransmission at the time (eg, n + 16th subframe) to perform the next retransmission. As another example, the terminal may perform asynchronous adaptive retransmission at any time after recognizing that the base station has failed to receive the uplink transmission.

Asynchronous HARQ Retransmission Method

9 is a diagram illustrating an uplink data transmission processing procedure of a terminal according to another embodiment of the present invention.

Environments using the unlicensed frequency band based on CA or dual connectivity typically have low terminal speed, low number of terminals handled by the base station, or stable radio quality of the unlicensed frequency band. E-UTRAN is based on synchronous HARQ retransmission, there is a problem that can cause a delay of time if the uplink data transmission or retransmission fails. If the UE fails to uplink transmission or retransmission due to the occupancy / collision occurring temporarily in the unlicensed frequency band, there may be a problem that the transmission speed of the terminal decreases due to an increase in delay.

In order to solve this problem, the terminal of the present invention detects the occupancy or collision on the radio link or when the uplink transmission is not performed to a specific TTI when the energy level exceeds a certain threshold value, the corresponding uplink data is available at the next transmission time. Can transmit Alternatively, the terminal may transmit the corresponding uplink data at the next available transmission time on the received uplink grant. Alternatively, the terminal may transmit data (MAC PDU) not performing uplink transmission to the specific TTI described above at a possible time during the transmission time. In summary, the terminal may use asynchronous retransmission with uplink HARQ of the unlicensed band cell.

When the terminal does not perform uplink transmission to a specific TTI by the LBT operation, the base station sends a higher layer message (for example, configuration information for transmitting uplink data that has not been transmitted to the specific TTI within a predetermined time). , An RRC reconfiguration message). Hereinafter, for convenience of description, when uplink transmission is not performed to a specific TTI by the LBT operation, configuration information for transmitting uplink data that has not been transmitted to the specific TTI within a predetermined time is referred to as "unlicensed band. Maximum retransmission time range associated with the cell's LBT operation. Alternatively, the base station may instruct the terminal to set the configuration information through the L1 / L2 signaling message. Alternatively, the configuration information may be included in the information configuring the unlicensed band cell and may be indicated, or may be indicated in the related MAC configuration information. Alternatively, the configuration information may be indicated through other information. The terminal may transmit uplink data that could not be transmitted at the next available transmission time, the next available transmission time on the received uplink grant, or a later transmission time using the corresponding configuration information. For example, when the maximum retransmission time range configuration information (or configuration information) related to the LBT operation of the unlicensed band cell is configured in the terminal, the base station may transmit uplink scheduling grants for a plurality of subframes / TTIs. As another example, if the above configuration information is configured in the terminal, when the base station does not perform the uplink transmission by the LBT operation to the corresponding subframe / TTI within the maximum retransmission time range associated with the LBT operation of the unlicensed band cell, It may allow (or know) to attempt uplink transmission in the next subframe / TTI. As another example, when the above configuration information is configured in the terminal, when the terminal does not perform the uplink transmission by the LBT operation to the corresponding subframe / TTI within the maximum retransmission time range associated with the LBT operation of the unlicensed band cell, A control may be made to attempt uplink transmission in a subframe / TTI.

Hereinafter, referring to FIG. 9, a case in which a UE has an uplink grant that can be transmitted with the same MCS or another MCS on the same resource or on another resource for four subframes will be described. This means that if the maximum retransmission time range related to the LBT operation of the unlicensed band cell described above is 4, or the uplink scheduling is received while the maximum retransmission time range related to the LBT operation of the unlicensed band cell described above is 4 Indicates.

Referring to FIG. 9, the terminal transmits HARQ information associated with the received uplink grant or uplink grant to the HARQ entity or the MAC layer (S910).

For example, in a situation in which the UE has a C-RNTI, the UE has a TTL, a serving cell to which the TAG in which the timeAlignmentTimer operates, and each grant received in the TTI has an uplink grant for the corresponding TTI and the serving cell. When received on the PDCCH for the C-RNTI that the terminal has, it may transmit HARQ information associated with the uplink grant to the HARQ entity. Alternatively, when the uplink grant for the corresponding TTI is received through a random access response, the terminal may transmit HARQ information associated with the uplink grant to the HARQ entity.

The terminal transmits a MAC PDU to be transmitted with the uplink grant or the uplink grant associated with the uplink grant indicated for the TTI to the given TTI through the HARQ entity to the HARQ process to generate a transmission to the corresponding TTI (S920). In addition, the UE instructs the HARQ process identified through the HARQ entity to trigger a new transmission or generate an adaptive retransmission (S920).

For example, for a given TTI, if an uplink grant is indicated for that TTI, the HARQ entity identifies the HARQ process for which the transmission will occur. The HARQ process is identified through the HARQ process ID included in the received HARQ information. In addition, the HARQ entity routes the received HARQ feedback, MCS and resources to the appropriate HARQ process.

For each TTI, the HARQ entity identifies the HARQ process associated with that TTI. For example, the HARQ entity identifies the HARQ process through the HARQ process ID included in the received HARQ information. The HARQ entity satisfies a specific condition for each identified HARQ process, and if there is data in the asynchronous HARQ buffer, acquires a MAC PDU to be transmitted from the asynchoronous HARQ buffer, and identifies the MAC PDU, uplink grant and HARQ information. And instruct the identified HARQ process to trigger the transmission. If there is no data in the asynchronous HARQ buffer or does not use the asynchronous HARQ buffer, the HARQ entity obtains the MAC PDU to transmit from the "Multiplexing and assembly" entity and forwards the MAC PDU, uplink grant and HARQ information to the identified HARQ process. And instruct the identified HARQ process to trigger the transmission. Here, the specific condition is that if the uplink grant is indicated to the corresponding HARQ process and the corresponding TTI, if the received grant is provided with the NDI toggled relative to the value for the previous transmission of this HARQ process, the associated HARQ information, It means a condition that satisfies one of the case where the received HARQ buffer received on the PDCCH for the C-RNTI is empty and there is no previous NDI for the corresponding HARQ process. The asynchoronous HARQ buffer described above will be described separately below.

In the present embodiment, the terminal may additionally instruct the radio link energy detection of the unlicensed band cell in step S920. Alternatively, the terminal may instruct radio link energy detection of the unlicensed band cell before step S920. For example, the radio link energy detection indication of the unlicensed band cell may be performed before step S910 or step S910 or between steps S910 and S920. The HARQ entity may have an indication of radio link energy sensing of an unlicensed band cell. For example, the HARQ entity first performs the step of instructing radio link energy detection of an unlicensed band cell. If the occupancy / collision is detected on the radio link or the energy level exceeds a certain threshold, the terminal does not perform uplink transmission. That is, the procedure may be terminated without performing uplink transmission for the corresponding uplink grant. In this case, when the UE detects radio link energy at the corresponding uplink transmission time with respect to the received uplink grant, the terminal does not store the MAC PDU in the HARQ buffer to trigger a new transmission. Or, return the MAC PDU obtained from the "Multiplexing and assembly" entity. Or, do not acquire a MAC PDU to transmit from the "Multiplexing and assembly" entity. In this way, MAC PDUs not used for new transmissions at the corresponding uplink transmission time can be quickly transmitted to the next transmission opportunity.

In a cell using an unlicensed frequency band, the UE or the physical layer detects or detects a radio link for a predetermined time (S930). Alternatively, the MAC layer (eg, HARQ entity or HARQ process) may perform step S930.

If the occupancy / collision is not detected on the wireless link or the energy level is lower than a specific threshold, the terminal may perform uplink transmission. For example, the HARQ process may instruct the physical layer to generate a transmission according to an uplink grant stored with a current redundancy version in order to generate an uplink transmission (S950). The HARQ process may increase the current redundancy version by 1 (S960). As another example, when the radio link energy detection indication for the unlicensed band cell is performed before step S920, for each TTI, the HARQ entity identifies the HARQ process associated with the TTI and, for the identified HARQ process, “Multiplexing and assembly Obtain the MAC PDU to transmit from the entity, forward the uplink grant and the MAC PDU to the HARQ process, and direct the transmission / retransmission generation.

If the occupancy / collision is detected on the wireless link or the energy level exceeds a certain threshold, the terminal may not perform the uplink transmission / retransmission (S940).

For example, the HARQ process may transfer information stored in the HARQ buffer to a temporary asynchronous HARQ buffer and flush the HARQ buffer.

As another example, the HARQ process may set the HARQ buffer as an asynchronous HARQ buffer. The Asynchronous HARQ buffer may be used by the HARQ entity at the next available transmission time, the next available transmission time on the received uplink grant, or the next retransmission time range associated with the LBT operation of the unlicensed band cell configured by the base station. In the step of transmitting the uplink grant and the like to the HARQ process, the contents of the asynchronous HARQ buffer may be stored as the HARQ buffer of the identified HARQ process to be delivered to the corresponding TTI, and the asynchronous HARQ buffer may be flushed.

As another example, the HARQ process may maintain a HARQ buffer. If the base station receives the data, the base station may trigger a new transmission for the HARQ process. The UE may store a new MAC PDU in the HARQ buffer when a new transmission for the corresponding HARQ process is triggered. If the base station does not receive the data, the base station may instruct an adaptive retransmission for the HARQ process. The UE may perform adaptive retransmission through the HARQ buffer stored for the corresponding HARQ process in the maximum retransmission time range associated with the LBT operation of the unlicensed band cell. When the UE performs adaptive retransmission for the corresponding HARQ process, the HARQ process increases the 'CURRENT_TX_NB' by 1, stores the uplink grant received from the HARQ entity, and transmits the 'CURRENT_IRV' to the HARQ information. One or more of the operation of setting an index corresponding to a version value, setting 'HARQ_FEEDBACK' to NACK, and increasing a variable representing the maximum retransmission time range state related to LBT operation of an unlicensed band cell by 1 Can be. The variable representing the maximum retransmission time range state associated with LBT operation of an unlicensed band cell is set to 0 on an LBT initial attempt or an initial transmission attempt that is toggled to NDI, and then incremented by 1 depending on the transmission attempt associated with the LBT operation of an unlicensed band cell. Can be.

As another example, for a corresponding HARQ process, such as TTI bundling, the UE may perform HARQ retransmission in the next subframe in a maximum retransmission time range related to LBT operation of an unlicensed band cell without HARQ feedback or explicit scheduling grant. For example, in the first subframe / TTI of the maximum retransmission time range associated with LBT operation of an unlicensed band cell, if occupancy / collision is detected on the radio link or the energy level does not perform uplink transmission above a certain threshold, An uplink transmission may be attempted in the second consecutive subframe / TTI of the maximum retransmission time range associated with the LBT operation of the unlicensed band cell. That is, this operation may be repeatedly performed until a subframe in which TTI bundling is set. For example, if the maximum retransmission time range related to LBT operation of an unlicensed band cell is set to 4 subframes, uplink transmissions up to 4 subframes / TTIs may be attempted even if uplink transmissions are not performed for 3 consecutive LBT reasons. Can be.

As another example, the prior art TTI bundling was applicable only to the case where the SCell is not configured at the cell boundary where the radio environment is not good. On the other hand, since the unlicensed band cell has a small cell coverage environment, the LBT succeeds (e.g., when the energy level is lower than a specific threshold) within the maximum retransmission time range related to the LBT operation of the unlicensed band cell described above. In case of attempting transmission, the UE may be configured not to perform uplink transmission in the remaining subframe in the maximum retransmission time range related to the LBT operation of the unlicensed band cell.

How to Set Uplink HARQ Transmission Parameters for Unlicensed Band Cell to Cell Specific

The uplink configuration information (ul-SCH-Config) is included in the MAC-MainConfig information element. Therefore, when the terminal is configured through a single base station, since the terminal has one MAC-MainConfig, the terminal is configured with one value for each parameter regardless of the cell (s) to be configured. When the terminal is configured through two base stations through the dual connectivity, the terminal has two MAC-MainConfig, so each base station is configured with one value for each parameter regardless of the cell (s) configured in each base station.

As described above, in order to use an unlicensed frequency band in an E-UTRAN, a cell using an unlicensed frequency band may have an LBT constraint. If there are many collisions in the unlicensed frequency band, it may be desirable to make the retransmission by the ARQ function of the RLC layer faster than to perform the retransmission up to HARQ maximum retransmission (current default value of E-UTRAN is 5). This allows retransmission through the PCell. To this end, the maximum number of HARQ transmissions (maxHARQ-Tx) of the unlicensed frequency band cell may be set separately from other cells (for example, PCell) or Mac-MainConfig.

Alternatively, if the unlicensed band cell is to provide asynchronous HARQ, it may set the maximum transmission timeout instead of the maximum number of transmissions to flush the HARQ buffer.

Hereinafter, an operation of a base station capable of performing all the operations required to apply each embodiment of the present invention described above with reference to FIG. 10 will be described.

10 is a view for explaining the operation of the base station according to another embodiment of the present invention.

In a method for receiving uplink data, a base station according to another embodiment of the present invention comprises a step of configuring carrier aggregation in a terminal including an unlicensed band cell using a frequency shared by one or more communication systems and an unlicensed band cell. And transmitting scheduling information for uplink transmission in the UE and receiving the uplink data transmitted from the terminal based on the scheduling information and whether the unlicensed band cell is available.

Referring to FIG. 10, the base station of the present invention includes a step of configuring carrier aggregation in a terminal including an unlicensed band cell using a frequency shared by one or more communication systems (S1010). For example, the base station may configure carrier aggregation in the terminal using an unlicensed band cell and a licensed band cell. Specifically, the base station may transmit information necessary for configuring carrier aggregation to the terminal to the terminal.

In addition, the base station includes the step of transmitting the scheduling information for uplink transmission in the unlicensed band cell (S1020). For example, the base station may transmit scheduling information necessary for the terminal to transmit the uplink data in the unlicensed band cell. The scheduling information may include uplink grants and the like.

In addition, the base station includes receiving the uplink data transmitted from the terminal based on the scheduling information and whether the unlicensed band cell is available (S1030). As described above, when the base station receives the uplink data from the terminal, the base station may receive the uplink data transmitted at a possible time by performing the LBT operation prior to receiving the uplink data. For example, a hybrid automatic repeat request (HARQ) entity of the terminal is a HARQ process for performing uplink data transmission when an unlicensed band cell is available, and a medium access control (MAC) protocol data unit (PDU) and an uplink grant. One or more of (UL grant) and HARQ information may be delivered. This allows the base station to receive uplink data. As another example, the uplink data may be data transmitted when the unlicensed band cell becomes available through an asynchronous retransmission procedure when the unlicensed band cell is unavailable. As another example, when the unlicensed band cell is an unavailable period, the uplink data may be data transmitted when the unlicensed band cell becomes an available interval by determining whether the next transmission time interval (TTI) is an available interval. The maximum value of the next TTI may be a value set by the base station, and the base station may transmit the corresponding value to the terminal. The maximum value of the next TTI may indicate the maximum retransmission time range associated with the LBT operation of the unlicensed band cell described above.

In addition, the base station may perform all of the base station operations required for the terminal to implement each of the above-described embodiments.

As described above, the present invention uses an unlicensed band cell in an E-UTRAN, whereby the terminal detects a radio link before uplink transmission and transmits / retransmits the uplink so that the terminal efficiently uplinks while satisfying the LBT constraint. Provides the effect of performing a transfer.

Referring to Figures 11 and 12, the configuration of the above-described terminal and base station will be briefly described.

11 is a view for explaining a terminal configuration according to another embodiment of the present invention.

Referring to FIG. 11, the terminal 1100 of the present invention includes an unlicensed band cell using a frequency shared by one or more communication systems and performs uplink transmission in the unlicensed band cell and the control unit 1110 constituting carrier aggregation. When the receiving unit 1130 for receiving the scheduling information for and the unlicensed band cell is an available period, and includes a transmitting unit 1120 for transmitting uplink data based on the scheduling information, the control unit 1110 is used by the unlicensed band cell It further comprises a configuration for determining whether or not the possible section.

The controller 1110 is a HARQ process in which a hybrid automatic repeat request (HARQ) entity of the terminal 1100 performs uplink data transmission when an unlicensed band cell is available, and a medium access control (MAC) protocol data unit (PDU). ), One or more of an UL grant and HARQ information can be controlled.

In addition, the control unit 1110 detects the energy of the radio link of the unlicensed band cell before the uplink data transmission necessary to perform the above-described invention, and according to the result of the overall terminal of the retransmission of the uplink data Control the operation.

When the unlicensed band cell is in an unavailable period, the transmitter 1120 may transmit uplink data when the unlicensed band cell becomes an available interval through an asynchronous retransmission procedure. In addition, when the unlicensed band cell is an unavailable period, the transmitter 1120 may determine whether the next TTI is an available interval, and may transmit uplink data when the unlicensed band cell becomes an available interval. Here, the maximum value of the next TTI is a value set by the base station.

The transmitter 1130 transmits uplink control information, data, and a message to a base station through a corresponding channel.

The receiver 1130 receives downlink control information, data, and a message from a base station through a corresponding channel. In addition, the receiver 1130 may receive necessary configuration information, indication information, etc. from the base station according to each embodiment.

12 is a view for explaining the configuration of a base station according to another embodiment of the present invention.

Referring to FIG. 12, the base station 1200 of the present invention includes an unlicensed band cell using a frequency shared by one or more communication systems and a control unit 1210 constituting carrier aggregation in a terminal and an uplink in an unlicensed band cell. A transmitter 1220 for transmitting scheduling information for transmission, and a receiver 1230 for receiving the uplink data transmitted from the terminal based on the scheduling information and whether the unlicensed band cell is available.

The control unit 1210 detects the energy of the radio link of the unlicensed band cell before the uplink data transmission by the terminal required to perform the above-described present invention, and performs an overall retransmission of the uplink data according to the result. To control the operation.

Meanwhile, when the unlicensed band cell is in an unusable section, the receiver 1230 may receive the transmitted data as uplink data when the unlicensed band cell becomes an available section through an asynchronous retransmission procedure. In addition, when the unlicensed band cell is an unusable section, the receiver 1230 determines whether the next transmission time interval (TTI) is an available section and receives the transmitted data as uplink data when the unlicensed band cell is an available section. can do.

The controller 1210 may set the maximum value of the following TTI.

The transmitter 1220 and the receiver 1230 are used to transmit and receive signals, messages, and data necessary for carrying out the present invention.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is related to the patent application No. 10-2014-0094984 filed in Korea on July 25, 2014 and the patent application No. 10-2015-0090831 filed in Korea on June 26, 2015. Priority is claimed under section (a) (35 USC § 119 (a)), all of which is incorporated by reference in this patent application. In addition, if this patent application claims priority for the same reason for countries other than the United States, all its contents are incorporated into this patent application by reference.

Claims (20)

1. In the method for the terminal to transmit the uplink data,

   Configuring a carrier coalescing comprising an unlicensed band cell using a frequency shared by one or more communication systems;

   Receiving scheduling information for uplink transmission in the unlicensed band cell;

   Determining whether the unlicensed band cell is an available interval; And

   If the unlicensed band cell is an available interval, transmitting uplink data based on the scheduling information.
2. The method of claim 1,

   If the unlicensed band cell is an available interval,

   A hybrid automatic repeat request (HARQ) entity of the terminal is a HARQ process for performing the uplink data transmission. The HARQ entity performs at least one of medium access control (MAC) protocol data unit (PDU), uplink grant (UL grant), and HARQ information. Delivering.
3. The method of claim 1,

   If the unlicensed band cell is an unavailable period,

   And transmitting the uplink data when the unlicensed band cell becomes available through an asynchronous retransmission procedure.
4. The method of claim 1,

   If the unlicensed band cell is an unavailable period,

   And determining whether a next transmission time interval (TTI) is an available interval, and if the unlicensed band cell becomes an available interval, transmitting the uplink data.
5. The method of claim 4, wherein

   The maximum value of the next TTI is,

   And a value set by the base station.
6. In the method for the base station to receive the uplink data,

   Configuring carrier aggregation in a terminal including an unlicensed band cell using a frequency shared by one or more communication systems;

   Transmitting scheduling information for uplink transmission in the unlicensed band cell; And

   Receiving uplink data transmitted from the terminal based on the scheduling information and whether an unlicensed band cell is available.
7. The method of claim 6,

   Hybrid automatic repeat request (HARQ) entity of the terminal,

   When the unlicensed band cell is an available period, one or more of a medium access control (MAC) protocol data unit (PDU), an uplink grant (UL grant), and HARQ information are transmitted to an HARQ process that performs the uplink data transmission. Characterized in that.
8. The method of claim 6,

   The uplink data is,

   And when the unlicensed band cell is in an unusable interval, the unlicensed band cell is data transmitted when the unlicensed band cell becomes an available interval through an asynchronous retransmission procedure.
9. The method of claim 6,

   The uplink data is,

   When the unlicensed band cell is an unusable interval, determining whether a next transmission time interval (TTI) is an available interval and transmitting data when the unlicensed band cell becomes an available interval.
10. The method of claim 9,

    The maximum value of the next TTI is,

    And a value set by the base station.
11. In the terminal for transmitting uplink data,

    A control unit for configuring carrier aggregation, including an unlicensed band cell using a frequency shared by one or more communication systems;

    A receiver which receives scheduling information for uplink transmission in the unlicensed band cell; And

    If the unlicensed band cell is an available interval, and includes a transmitter for transmitting uplink data based on the scheduling information,

    The controller further determines whether the unlicensed band cell is an available section.
12. The method of claim 11,

    The control unit,

    When the unlicensed band cell is an available period, a medium automatic access request (MAC) protocol access unit (PDU) and an uplink grant are HARQ processes in which a hybrid automatic repeat request (HARQ) entity of the terminal performs the uplink data transmission. (UL grant) and the terminal characterized in that the control to transmit at least one of HARQ information.
13. The method of claim 11,

    The transmitting unit,

    When the unlicensed band cell is an unusable period, the uplink data is transmitted when the unlicensed band cell becomes an available period through an asynchronous retransmission procedure.
14. The method of claim 11,

    The transmitting unit,

    When the unlicensed band cell is an unusable period, the UE determines whether a next transmission time interval (TTI) is an available period and transmits the uplink data when the unlicensed band cell is an available period.
15. The method of claim 14,

    The maximum value of the next TTI is,

    And a terminal set by the base station.
16. A base station for receiving uplink data,

    A control unit for configuring carrier aggregation in a terminal, including an unlicensed band cell using a frequency shared by one or more communication systems;

    A transmitter for transmitting scheduling information for uplink transmission in the unlicensed band cell; And

    And a receiving unit which receives the uplink data transmitted from the terminal based on the scheduling information and whether the unlicensed band cell is available.
17. The method of claim 16,

    Hybrid automatic repeat request (HARQ) entity of the terminal,

    When the unlicensed band cell is an available period, one or more of a medium access control (MAC) protocol data unit (PDU), an uplink grant (UL grant), and HARQ information are transmitted to an HARQ process that performs the uplink data transmission. A base station characterized in that.
18. The method of claim 16,

    The uplink data is,

    When the unlicensed band cell is in an unusable interval, the base station characterized in that the data is transmitted when the unlicensed band cell becomes an available interval through an asynchronous retransmission procedure.
19. The method of claim 16,

    The uplink data is,

    When the unlicensed band cell is an unusable interval, the base station, characterized in that the data is transmitted when the unlicensed band cell becomes an available interval by determining whether a next transmission time interval (TTI) is an available interval.
20. The method of claim 19,

    The maximum value of the next TTI is,

    The base station, characterized in that the value set by the base station.

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