KR20160046712A

KR20160046712A - Methods for transmitting data using an unlicensed spectrum and Apparatuses thereof

Info

Publication number: KR20160046712A
Application number: KR1020150112969A
Authority: KR
Inventors: 김성관; 김병석; 김일환; 김홍준
Original assignee: 주식회사 케이티
Priority date: 2014-10-21
Filing date: 2015-08-11
Publication date: 2016-04-29

Abstract

The present invention relates to a method and apparatus for transmitting data using an unlicensed frequency band, and more particularly to a method and apparatus which prevent systems from colliding between a licensed frequency band and an unlicensed frequency band and transmit and receive the data. In particular, the present invention provides a method by which a base station transmits data, comprising the steps of: transmitting addition configuration information to add a carrier using an unlicensed frequency band to a secondary carrier, to a terminal; transmitting occupation reservation information including information on a time section of the unlicensed frequency band required to transmit downlink data; and transmitting the downlink data via the secondary carrier according to the occupation reservation information.

Description

[0001] The present invention relates to a method and apparatus for transmitting data using an unlicensed frequency band,

The present invention relates to a method and apparatus for transmitting and receiving data using a license-exempt frequency band. More particularly, to a method and apparatus capable of transmitting and receiving data while preventing system conflicts between the license frequency band and the license-exempt frequency band.

As communications systems evolved, consumers, such as businesses and individuals, used a wide variety of wireless terminals. In a mobile communication system such as LTE (Long Term Evolution) and LTE-Advanced of the current 3GPP series, a high-speed and large-capacity communication system capable of transmitting and receiving various data such as video and wireless data outside a voice- It is required to develop a technique capable of transmitting large-capacity data in accordance with the above-described method. It is possible to efficiently transmit data using a plurality of cells in a method for transmitting a large amount of data.

However, there is a limit to providing a base station to a plurality of terminals that transmit large amount of data using limited frequency resources. In other words, securing a frequency resource that can be used exclusively by a specific service provider is costly.

On the other hand, license-exempt frequency bands that can not be used exclusively by specific operators or specific communication systems can be shared by multiple operators or communication systems. For example, WLAN technology, represented by Wi-Fi, provides data transmission and reception services using frequency resources of the license-exempt band.

Accordingly, a mobile communication system is also required to study a technique of transmitting / receiving data to / from a terminal using a corresponding Wi-Fi AP (Access Point).

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a method and an apparatus for avoiding a collision with another communication system or a terminal in transmitting and receiving data by adding a license-unlicensed frequency band as a carrier to a terminal and a base station.

The present invention also provides a method and apparatus for transmitting / receiving data while avoiding collision using a license-exempt frequency band even if an additional function for collision avoidance is not added to an existing terminal or a WLAN AP.

According to another aspect of the present invention, there is provided a method for transmitting data to a base station, the method comprising: transmitting additional configuration information to a terminal for adding a carrier using a license-based frequency band to a secondary carrier; And transmitting the occupancy reservation information including the information on the time period of the non-license frequency band required for the occupancy reservation information and the downlink data through the secondary carrier according to occupancy reservation information.

According to another aspect of the present invention, there is provided a method of receiving data from a terminal, the method comprising: receiving additional configuration information for adding a carrier using an unlicensed frequency band to a secondary carrier; And receiving downlink data through a secondary carrier in a time interval exclusively occupied according to the occupancy reservation information transmitted by the base station.

The present invention also provides a base station for transmitting data, comprising: a transmitter for transmitting additional configuration information for adding a carrier using a license-unoccupied frequency band as a secondary carrier to a terminal; and a transmitter for transmitting time- And a transmitter for transmitting the occupancy reservation information and transmitting the downlink data through the secondary carrier according to the occupation reservation information.

According to another aspect of the present invention, there is provided a terminal for receiving data, comprising: a receiving unit for receiving additional configuration information for adding a carrier using a license-exempt frequency band to a secondary carrier; Wherein the receiving unit receives the downlink data through the secondary carrier in a time interval occupied exclusively according to the occupancy reservation information transmitted by the base station.

As described above, the present invention provides a method and apparatus for avoiding a collision with another communication system or a terminal in transmitting and receiving data by adding a license-unlicensed frequency band to one carrier as a carrier.

In addition, the present invention provides a method and apparatus for transmitting / receiving data while avoiding collision using a license-exempt frequency band even when an additional function for collision avoidance is not added to an existing terminal or a WLAN AP.

FIG. 1 is a diagram for explaining the collision avoidance method of the present invention with respect to each node in a WLAN access point (AP), for example.
FIG. 2 is a diagram for explaining the collision avoidance method of the present invention, for example, with reference to a base station.
3 is a view for explaining a base station operation according to an embodiment of the present invention.
4 is a diagram for explaining a terminal operation according to another embodiment of the present invention.
5 is a view for explaining a base station operation including transmission of a synchronization signal according to another embodiment of the present invention.
6 is a flowchart illustrating a base station operation including synchronization signal transmission according to the present invention.
7 is a diagram for explaining a terminal operation including reception of a synchronization signal according to another embodiment of the present invention.
8 is a diagram illustrating a base station configuration according to another embodiment of the present invention.
9 is a diagram illustrating a configuration of a user terminal according to another embodiment of the present invention.

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

Herein, the MTC terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. In this specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) and coverage enhancement. Alternatively, the MTC terminal may refer to a terminal defined in a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, the MTC terminal may refer to a newly defined 3GPP Release 13 low cost (or low complexity) UE category / type for performing LTE-based MTC-related operations. Alternatively, the MTC terminal may support enhanced coverage over the existing LTE coverage or a UE category / type defined in the existing 3GPP Release-12 or lower that supports low power consumption, or a newly defined Release-13 low cost low complexity UE category / type.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data and the like. A wireless communication system includes a user equipment (UE) and a base station (BS, or eNB). The user terminal in this specification is a comprehensive concept of a terminal in wireless communication. It is a comprehensive concept which means a mobile station (MS), a user terminal (UT), an SS (User Equipment) (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 (eNB), a sector, a Site, a BTS A base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell.

That is, the base station or the cell in this specification is interpreted as a comprehensive meaning indicating a partial region or function covered by BSC (Base Station Controller) in CDMA, NodeB in WCDMA, eNB in LTE or sector (site) And covers various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, and small cell communication range.

Since the various cells listed above exist in the base station controlling each cell, the base station can be interpreted into two meanings. i) the device itself providing a megacell, macrocell, microcell, picocell, femtocell, small cell in relation to the wireless region, or ii) indicating the wireless region itself. i indicate to the base station all devices that are controlled by the same entity or that interact to configure the wireless region as a collaboration. An eNB, an RRH, an antenna, an RU, an LPN, a point, a transmission / reception point, a transmission point, a reception point, and the like are exemplary embodiments of a base station according to a configuration method of a radio area. ii) may indicate to the base station the wireless region itself that is to receive or transmit signals from the perspective of the user terminal or from a neighboring base station.

Therefore, a base station is collectively referred to as a base station, collectively referred to as a megacell, macrocell, microcell, picocell, femtocell, small cell, RRH, antenna, RU, low power node do.

Herein, the user terminal and the base station are used in a broad sense as the two transmitting and receiving subjects used to implement the technical or technical idea described in this specification, and are not limited by a specific term or word. The user terminal and the base station are used in a broad sense as two (uplink or downlink) transmitting and receiving subjects used to implement the technology or technical idea described in the present invention, and are not limited by a specific term or word. Here, an uplink (UL, or uplink) means a method of transmitting / receiving data to / from a base station by a user terminal, and a downlink (DL or downlink) .

There are no restrictions on multiple access schemes applied to wireless communication systems. Various multiple access schemes 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- Can be used. An embodiment of the present invention can be applied to asynchronous wireless communication that evolves into LTE and LTE-Advanced via GSM, WCDMA, and HSPA, and synchronous wireless communication that evolves into CDMA, CDMA-2000, and UMB. The present invention should not be construed as limited to or limited to a specific wireless communication field and should be construed as including all technical fields to which the idea of the present invention can be applied.

A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

In systems such as LTE and LTE-Advanced, the uplink and downlink are configured on the basis of one carrier or carrier pair to form a standard. The uplink and the downlink are divided into a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel, a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control Channel (EPDCCH) Transmits control information through the same control channel, and is configured with data channels such as PDSCH (Physical Downlink Shared CHannel) and PUSCH (Physical Uplink Shared CHannel), and transmits data.

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

In this specification, a cell refers to a component carrier having a coverage of a signal transmitted from a transmission point or a transmission point or transmission / reception point of a signal transmitted from a transmission / reception point, and a transmission / reception point itself .

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

The multi-point transmission / reception point includes a base station or a macro cell (hereinafter referred to as 'eNB'), and at least one mobile station having a high transmission power or a low transmission power in a macro cell area, Lt; / RTI >

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

Hereinafter, a situation in which a signal is transmitted / received through a channel such as PUCCH, PUSCH, PDCCH, EPDCCH, and PDSCH is expressed as 'PUCCH, PUSCH, PDCCH, EPDCCH and PDSCH are transmitted and received'.

In the following description, an indication that a PDCCH is transmitted or received or a signal is transmitted or received via a PDCCH may be used to mean transmitting or receiving an EPDCCH or transmitting or receiving a signal through an EPDCCH.

That is, the physical downlink control channel described below may mean a PDCCH, an EPDCCH, or a PDCCH and an EPDCCH.

Also, for convenience of description, EPDCCH, which is an embodiment of the present invention, may be applied to the portion described with PDCCH, and EPDCCH may be applied to the portion described with EPDCCH according to an embodiment of the present invention.

Meanwhile, the High Layer Signaling described below includes RRC signaling for transmitting RRC information including RRC parameters.

The eNB performs downlink transmission to the UEs. The eNB includes a physical downlink shared channel (PDSCH) as a main physical channel for unicast transmission, downlink control information such as scheduling required for reception of PDSCH, and uplink data channel A physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission in a Physical Uplink Shared Channel (PUSCH). Hereinafter, the transmission / reception of a signal through each channel will be described in a form in which the corresponding channel is transmitted / received.

Currently, LTE technology is being developed to utilize a large number of frequency resources such as multi-carrier and carrier aggregation. In addition, due to the explosion of terminals such as smart phones, frequency resources shortage is expected to appear in many countries. The present invention relates to a technology that uses an unlicensed spectrum together with a Wi-Fi device without interference to a Wi-Fi device by an LTE base station or a terminal, and can efficiently cope with the expected frequency shortage The purpose of the invention is to provide a technical basis for the invention.

The Long Term Evolution (LTE) technology defined by 3GPP does not support the Listen Before Talk (LBT) technology required to use the license-exempt frequency band as a technology for using the licensed spectrum. Accordingly, when an LTE system is operated in the license-exempt frequency band, other systems or equipment using the license-exempt frequency band may experience mutual interference problems.

In order to solve such a problem, the present invention uses a license-exempt frequency band of an LTE system (for example, a base station and a terminal) based on 3GPP Release 9-12 that does not support LBT technology, which is an essential element for using a license- And to transmit data without mutual interference with other technology equipment.

The license-exempt frequency band subject technology being discussed in the 3GPP standardization group is called the so-called LTE-unlicensed spectrum (LTE-U). In LTE-U, standardization is being pursued with the goal of preferentially using the 5GHz band, which is relatively less frequently used, among 2.4GHz and 5GHz bands, which are representative license-exempt frequency bands. The IEEE 802.11a / n / ac, which is mainly used in the 5GHz band, has a MAC (Medium Access Control layer) based on Carrier Sense Multiple Access and Collision Avoidance (CSMA / CA) and an Orthogonal Frequency Division Multiplexing Frequency Division Multiplexing (PHY) based on IEEE802.11g is used.

IEEE 802.11 CSMA / CA Overview of Technology

IEEE 802.11-based equipment operating in the 5 ㎓ licensed frequency band detects the transmission medium by itself, determines that the corresponding frequency band is not occupied by transmission of other equipment, and transmits its own packet. Such an operation method is called a CSMA method, and each device transmits a packet by decentralized or distributed scheduling. For reference, a medium access method in a mobile communication system is a centralized scheduling.

Since all equipment based on IEEE802.11 accesses the transmission medium in a distributed control manner, it is probable that two or more devices access the transmission medium at the same time. In this case, two or more packets can be transmitted simultaneously. This transmission becomes very unlikely to be normally received at the receiving end. This phenomenon is defined as a collision in the IEEE802.11 standard. IEEE 802.11 equipment performs a backoff procedure immediately before transmission to reduce potential collision probabilities in the future. If a transmission failure occurs due to a collision or the like, the backoff time is increased stochastically, and this procedure is further strengthened as the transmission failure is repeated. That is, when a transmission failure occurs, the backoff operation is performed for a longer time. In this way, the protection procedure to reduce the potential collision probability in the future in the environment where the medium of the distributed control method is performed is called the CA method.

In this specification, a device that transmits and receives WLAN data is termed an access point (AP) or a station (STA) by using terms defined in the IEEE 802.11 standard.

Overview of LTE Carrier Aggregation Technology

The LTE traffic transmission in the license-exempt frequency band considered in the present invention assumes the use of LTE Carrier Aggregation (LTE CA) technology. LTE CA is a technology that can use two or more carriers at the same time to theoretically increase the transmission speed that a single user can feel by the number of carriers. For example, assume that there are two 10 MHz carriers, and that the carrier is available to a single user via LTE CA technology. Since the maximum transmission speed that can be transmitted to each 10 MHz carrier is theoretically 75 Mbps, when two carriers are used for receiving data for the same time by a single user using LTE CA technology, theoretically, a transmission speed of 150 Mbps can be provided have.

The carrier of one of two or more carriers used in the LTE CA technology may be designated as a Primary Component Carrier (PCC), and the remaining carriers may be designated as a Secondary Component Carrier (SCC). Also, the primary component carrier may be described as a primary cell or a primary carrier. Likewise, the secondary element carrier wave can also be described as a secondary cell or a secondary carrier. In the present specification, the primary carrier, the primary cell, or the primary element carrier wave are used in the same sense as necessary. The secondary carrier, the secondary cell, or the secondary element carrier wave are used in the same sense. In the present invention, there is a primary carrier operating in a license frequency band, and a method of performing data transmission and reception by using some of the 5 GHz license-exempt frequency bands as a secondary carrier.

Listen Before Talk ( LBT Definition and necessity of motion

Since the LTE system is designed assuming IP packet transmission in the licensed frequency band, it is assumed that no other system uses the transmission band. Therefore, all the terminals access the transmission medium through the control of the base station (eNodeB) and transmit the packets. Therefore, all the transmission failure phenomenon is analyzed not by the collision between the packets but by the transmission power shortage and by adjusting the transmission power, modulation and coding scheme : Modulation scheme) adjustment to perform an operation for increasing the transmission success rate.

However, since LTE-U is aimed at using LTE technology for the 5 GHz license-exempt band, it is necessary to minimize mutual interference with IEEE 802.11 equipment already used in the band. Thus, procedures (or requirements) for protecting equipment already operating in the license-exempt band are defined as LBT. Various methods of MAC technology can be applied to meet LBT requirements, but specific procedures and methods for applying LBT technology in LTE systems have not been disclosed so far.

Also, when LBT technology for using LTE-U technology is applied, existing terminals using LTE technology may not be able to implement LBT technology. That is, the legacy terminal may not be able to use the license-exempt frequency band. Therefore, there is a need for a method for allowing existing terminals to use the license-exempt frequency band.

WLAN How to prevent collisions in equipment

WLAN technology has continued to evolve, improving transmission speed and frequency efficiency. Since WLAN technology has evolved into a basic philosophy of ensuring backward compatibility for legacy standards-based equipment, new technologies have been proposed and even if this is adopted as a standard, The environment must be provided. For example, in order to increase the transmission speed when the IEEE 802.11g standard is established, a modulation scheme with a higher efficiency than the short preamble format and the modulation scheme (MCS) defined in the existing standard has been defined. However, since the technology uses a preamble bit stream and a modulation scheme of a type that can not be recognized by an existing standard (e.g., IEEE 802.11b) based equipment, A protective device is needed to ensure the normal operation of the equipment following.

As described above, in the LTE technology, it is necessary to develop a method for ensuring compatibility when the existing terminal and the base station use the newly defined LTE-U technology.

First, the operation of the case where the collision avoidance method of the present invention is applied to the existing WLAN technology will be described as an example. That is, the case where the collision avoidance method of the present invention operates in the WLAN technology will be described as an example.

FIG. 1 is a diagram for explaining the collision avoidance method of the present invention with respect to each node in a WLAN access point (AP), for example.

Referring to FIG. 1, a device attempting to transmit data at a higher rate using the IEEE 802.11g preamble may transmit a CTS frame (CTS frame) 100 using an IEEE 802.11b preamble in advance . At this time, the Duration / ID field of the CTS frame 100 may record the time including the transmission time of the data 110 to be transmitted to the IEEE 802.11g preamble and the transmission time of the ACK frame 120. The other equipment that has received the CTS frame 100 sets a Network Allocation Vector (NAV) 130 as shown in FIG. 1 and does not attempt to access the wireless channel by itself during the corresponding time. The destination address of the CTS frame 100 depicted in FIG. 1 may use the address of the transmitting terminal itself. That is, even when the IEEE 802.11g terminal transmits data using a newly defined preamble, the CTS frame 100 is transmitted in order to ensure call completion with the existing terminal, and a data transmission time can be secured based on the transmitted CTS frame 100 .

That is, as described above with reference to FIG. 1, when the present invention is applied, the existing terminal can maintain the call completion with the terminal using the newly defined technology.

In the foregoing, the case where the method of the present invention is applied to the WLAN technology has been described in order to facilitate understanding. Hereinafter, a method of transmitting and receiving data between a terminal and a base station using the LTE technology will be described.

1 according to the present invention is applied to the base station and the terminal, and the LTE-U device follows the philosophy of the LBT for checking the state of the transmission medium immediately before the transmission of its own packet, We suggest a way to be compatible. In addition, the existing 3GPP Release 9-12 based LTE devices that do not implement additional LBT technology can perfectly coexist on the same transmission medium with IEEE 802.11 devices.

The LTE-U device equipped with the data collision prevention method proposed in the present invention is collocated and coexisting with an 802.11 terminal or AP module capable of transmitting a CTS frame over the IEEE802.11g protocol, It is assumed that the module and the IEEE802.11 module are time synchronized with each other. In addition, it is assumed that the traffic control message for the license-exempt frequency band LTE data transmission is transmitted to the primary carrier operating in the license band and the 5 GHz license-exempt band is used only as the secondary carrier.

FIG. 2 is a diagram for explaining the collision avoidance method of the present invention, for example, with reference to a base station.

Referring to FIG. 2, the transmitting terminal 250 of the present invention may include a WLAN AP or STA capable of transmitting the above-described CTS frame. Or the transmitting terminal 250 of the present invention may include the function of a WLAN AP or STA transmitting a CTS frame.

The transmitting terminal 250 of the present invention can add the license-exempt frequency band as a carrier and transmit the CTS frame 200 in the added carrier. For example, the BS determines whether a secondary carrier capable of using a license-free frequency band is available for an LTE terminal having a limited transmission bandwidth with only a primary carrier. When the terminal is a terminal capable of using the secondary carrier, the base station can estimate the size of data to be transmitted on the secondary carrier. Then, the base station can transmit additional configuration information for configuring the CA by adding a secondary carrier to the terminal. The terminal uses the received additional configuration information to The license-free frequency band can be added as a secondary carrier.

Meanwhile, the base station may transmit additional configuration information for the LTE CA to the terminal using the primary carrier, and then estimate the amount of data to be transmitted to the terminal through the secondary carrier. That is, it is possible to estimate the transmission time required for transmitting data through the secondary carrier.

The base station can transmit the CTS frame 200 in the corresponding unlicensed frequency band and reserve the occupation of the time 230 for downlink data transmission as described in FIG. The CTS frame 200 may include a duration / ID field for downlink transmission. That is, as described with reference to FIG. 1, the CTS frame 200 may include information on the time required for transmitting the corresponding data 210 and receiving the response information 220. Then, the base station can transmit the downlink data to the terminal through the secondary carrier at the occupied time 250. 210 and 220 are represented by data of IEEE 802.11g described in FIG. 1 for the sake of understanding, and the downlink data transmitted by the base station is transmitted as 230.

Upon receiving the CTS frame 200, the IEEE 802.11 terminal does not access the corresponding secondary carrier by setting the NAV 240 according to the time interval recorded in the duration / ID field.

Therefore, the base station and the terminal can transmit and receive data exclusively using the license-exempt frequency band for the corresponding time period. Through this, the terminal and the base station can obtain a transmission bandwidth expansion effect through the CA in the license-free frequency band.

Hereinafter, the above-described operation of the present invention will be described in more detail in terms of the base station and the terminal.

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

A method for transmitting data in a base station according to an embodiment of the present invention includes the steps of transmitting additional configuration information to a terminal for adding a carrier using an unlicensed frequency band to a secondary carrier, Transmitting occupancy reservation information including information on a time interval of a frequency band, and transmitting downlink data through a secondary carrier according to occupancy reservation information.

Referring to FIG. 3, the base station may include transmitting additional configuration information to the terminal for adding a carrier using the license-exempt frequency band to the secondary carrier (S310). For example, the BS can determine whether to perform CA using the license-free frequency band in consideration of the data transmission / reception state with the AT, the location information of the AT, or whether the AT supports the license-exempt frequency band. As described above, the license-exempt frequency band can be composed of a secondary carrier at the terminal. To this end, the base station may generate additional configuration information for adding the license-exempt frequency band to the secondary carrier and transmit the additional configuration information to the terminal. Additional configuration information may be sent via higher layer signaling, such as an RRC message. In addition, the base station can transmit additional configuration information to the terminal using the primary carrier.

In addition, the base station may include the step of transmitting occupancy reservation information including information on a time interval of a license-exempt frequency band required for downlink data transmission (S320). For example, the base station can estimate the size of downlink data to be transmitted to the mobile station using the secondary carrier. Also, the base station can estimate the time interval information for using the license-exempt frequency band using the estimated downlink data. The base station can transmit the occupancy reservation information including the estimated information to the terminal. The occupancy reservation information may include time interval information and identification information that the base station desires to occupy, and may refer to a CTS frame as described with reference to FIGS. The occupancy reservation information can be defined and transmitted so that both the existing LTE terminal and the base station or the WLAN equipment can receive it. Meanwhile, the time interval refers to radio resources exclusively occupied by the BS for downlink data transmission. For example, it means a license-exempt frequency band composed of secondary carriers and a time resource for transmission of downlink data.

The occupancy reservation information may include at least one of time information and destination address information necessary for transmitting a response signal to the downlink data. That is, the occupancy reservation information may include both the time resource expected to be used for transmitting the downlink data and the time resource necessary for the terminal to receive the downlink data and transmit the response signal. However, when the terminal is set to transmit the response signal to the primary carrier, the occupancy reservation information may include only information on the time resources required for transmitting the downlink data. The occupancy reservation information may further include destination address information, and the destination address information may be identification information of the base station or identification information of the WLAN equipment configured in the base station.

As described above, based on the occupation reservation information, the other LTE equipment and the WLAN equipment set the NAV in the corresponding time interval and do not approach the corresponding license-exempt frequency band.

In addition, the base station may include transmitting the downlink data through the secondary carrier according to occupancy reservation information (S330). The base station can transmit the downlink data to the terminal at a time when the other equipment is set to the NAV. At this time, the downlink data to be transmitted may be transmitted through the secondary carrier in the license-incapacitated frequency band which is further configured in the terminal.

Through the operations described above, the BS can exclusively occupy the license-exempt frequency band and transmit the downlink data to the UE. Likewise, when a terminal transmits uplink data, a secondary carrier may be additionally configured, and uplink data may be transmitted through occupied time resources after transmitting occupancy reservation information. Hereinafter, for convenience of explanation, the case of receiving downlink data will be described as an example, but the same can be applied to the case of transmitting uplink data as described above.

4 is a diagram for explaining a terminal operation according to another embodiment of the present invention.

A method for receiving data in a terminal according to another embodiment of the present invention includes receiving additional configuration information for adding a carrier using an unlicensed frequency band to a secondary carrier, Configuring a carrier as a secondary carrier, and receiving downlink data through a secondary carrier in a time period occupied exclusively according to occupancy reservation information transmitted by the base station.

Referring to FIG. 4, the terminal may include receiving additional configuration information for adding a carrier using the license-exempt frequency band to the secondary carrier (S410). For example, the terminal may receive additional configuration information including information necessary for adding a secondary carrier from the base station. Additional configuration information may be received via the primary carrier and received with higher layer signaling.

In addition, the terminal may include configuring the carrier in the license-exempt frequency band as a secondary carrier based on the additional configuration information (S420). For example, the terminal may further configure the terminal with a secondary carrier using the license-exempt frequency band using the received additional configuration information. That is, it is possible to configure or set a lower layer in the terminal for transmitting and receiving data and signals through the secondary carrier. If necessary, the secondary carrier can be set to receive only downlink data. In this case, the control signal and the response signal for the secondary carrier may be set to be transmitted and received via the primary carrier. Alternatively, the secondary carrier may be configured to transmit and receive both uplink and downlink data.

In addition, the UE may receive the downlink data through the secondary carrier in a time interval occupied exclusively according to the occupancy reservation information transmitted by the base station (S430). As described above, when the downlink data is received, the occupied reservation information can be transmitted by the base station. Conversely, when the terminal transmits uplink data, the terminal may generate and transmit occupancy reservation information. For example, occupancy reservation information may include at least one of time information and destination address information necessary for transmitting a response signal to downlink data. That is, the occupancy reservation information may include both the time resource expected to be used for transmitting the downlink data and the time resource necessary for the terminal to receive the downlink data and transmit the response signal. However, when the terminal is set to transmit the response signal to the primary carrier, the occupancy reservation information may include only information on the time resources required for transmitting the downlink data. The occupancy reservation information may further include destination address information, and the destination address information may be identification information of the base station or identification information of the WLAN equipment configured in the base station. The occupancy reservation information can be transmitted via the secondary carrier. On the other hand, the terminal can receive downlink data in a time period exclusively occupied according to occupation reservation information.

In the foregoing, a method of transmitting / receiving data by preventing collision with other equipment through occupied reservation information transmission according to an embodiment of the present invention has been described.

Hereinafter, a method of synchronizing the time synchronization required for transmitting and receiving data between the terminal and the base station via the secondary carrier will be described. In this case, the above-described collision avoidance method is applied, and a method of synchronizing with the exclusive occupied time interval will be described.

5 is a view for explaining a base station operation including transmission of a synchronization signal according to another embodiment of the present invention.

The base station according to another exemplary embodiment of the present invention transmits a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a system information block, and a cell-specific (CRS) signal in a time interval of a secondary carrier before a step of receiving downlink data and receiving the at least one of the reference signals.

Referring to FIG. 5, the base station may include transmitting additional configuration information to a terminal for adding a carrier using a license-free frequency band to a secondary carrier (S510). 3, the base station may determine whether to perform a CA using a license-exempt frequency band in consideration of a data transmission / reception state with the terminal, position information of the terminal, or whether the terminal supports the license-exempt frequency band have. As described above, the license-exempt frequency band can be composed of a secondary carrier at the terminal. To this end, the base station may generate additional configuration information for adding the license-exempt frequency band to the secondary carrier and transmit the additional configuration information to the terminal. Additional configuration information may be sent via higher layer signaling, such as an RRC message. In addition, the base station can transmit additional configuration information to the terminal using the primary carrier.

In addition, the base station may include the step of transmitting occupancy reservation information including information on a time interval of an unlicensed frequency band required for downlink data transmission (S520). The base station can estimate the size of the downlink data to be transmitted to the mobile station by using the secondary carrier as in step S320 of FIG. Also, the base station can estimate the time interval information for using the license-exempt frequency band using the estimated downlink data. The base station can transmit the occupancy reservation information including the estimated information to the terminal. The occupancy reservation information may include time interval information and identification information that the base station desires to occupy, and may refer to a CTS frame as described with reference to FIGS. The occupancy reservation information can be defined and transmitted so that both the existing LTE terminal and the base station or the WLAN equipment can receive it. Meanwhile, the time interval refers to radio resources exclusively occupied by the BS for downlink data transmission. For example, it means a license-exempt frequency band composed of secondary carriers and a time resource for transmission of downlink data.

The base station transmits at least one of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a system information block and a cell-specific reference signal (CRS) within a time interval of the secondary carrier before receiving the downlink data. And receiving a signal (S530). For example, the BS may transmit a signal for synchronization with the MS in a time period occupied exclusively through occupation reservation information. The signal for synchronization can be transmitted via the secondary carrier. In one example, the base station can transmit the PSS and the SSS via the secondary carrier, and the terminal can synchronize with the base station via the received PSS and SSS. In addition, the BS may transmit at least one of the PSS, the SSS, the SIB, and the CRS using the secondary carrier before transmitting the downlink data in the time interval of the occupancy reservation information. At least one of the PSS, the SSS, the SIB, and the CRS may not be transmitted any more when the occupation reservation time period of the secondary carrier ends.

In addition, the base station may include a step of transmitting downlink data through the secondary carrier according to occupancy reservation information (S540). The base station can transmit the downlink data to the terminal at a time when the other equipment is set to the NAV. At this time, the downlink data to be transmitted may be transmitted through the secondary carrier in the license-incapacitated frequency band which is further configured in the terminal.

6 is a flowchart illustrating a base station operation including synchronization signal transmission according to the present invention.

In order to transmit and receive data using the secondary carrier, the terminal must synchronize with the base station in the secondary carrier band (i.e., in the non-busy band). In the LTE system, the MS receives the Primary Synchronization Signal (PSS) and the Secondary Synchronization Signal (SSS) transmitted from the BS to acquire synchronization, and uses the information contained in the PSS / SSS to acquire a PCI (Physical Cell Identifier) . The terminal receives the PBCH (Physical Broadcast Channel) transmitted from the corresponding cell using the PCI and receives the SIB (System Information Base) containing the cell specific information transmitted to the PBCH. In addition, the location of the CRS (Cell-Specific Reference Signal) transmitted from the corresponding cell is determined using PCI.

Therefore, the secondary carrier in the license-free frequency band is a band coexisting with other systems, so that PSS, SSS, SIB, CRS can not always be transmitted unlike in the licensed band. Therefore, immediately after occupying the bandwidth due to the occupied reservation information, the base station starts transmission of the PSS, SSS, SIB, and CRS in the secondary carrier, assures the time for the terminal to secure synchronization with the base station, You have to start. Conversely, after the downlink data transmission is completed, the base station ends the PSS, SSS, SIB, CRS transmission in the secondary carrier band.

Referring to FIG. 6, the BS determines whether the amount of downlink data to be transmitted to the UE is equal to or greater than a reference value (S610). That is, it can be determined whether the downlink data to be transmitted to the terminal has increased as much as to be transmitted through the CA. In addition, the base station may determine whether the corresponding terminal supports the CA.

If it is determined that the downlink data is equal to or greater than the reference value, the base station may transmit the secondary carrier addition configuration information for adding the secondary carrier using the license-exempt frequency band to the terminal (S620). Thereafter, the terminal constructs a CA by additionally configuring a secondary carrier.

In step S630, the BS transmits the occupancy reservation information to the MS in order to transmit the downlink data using the secondary carrier. Occupancy reservation information may include time interval information required for transmitting downlink data to the terminal.

The BS transmits at least one of the PSS, the SSS, the SIB, and the CRS before the downlink data is transmitted in the occupied time interval through occupation reservation information (S640). That is, the base station transmits synchronization information, system information, and the like necessary for the UE to receive the downlink data in the exclusive occupation time period of the secondary carrier. The terminal receives signals such as PSS, SSS, SIB and CRS in a time occupied exclusively and prepares to receive downlink data.

Then, the base station transmits the downlink data in the occupied time period using the secondary carrier (S650). One or more of the PSS, SSS, SIB, and CRS may be continuously transmitted within a time interval in units of predetermined subframes or radio frames.

Through this, the UE can secure the synchronization in the base station and the secondary carrier and smoothly receive the downlink data.

7 is a diagram for explaining a terminal operation including reception of a synchronization signal according to another embodiment of the present invention.

The UE according to another embodiment of the present invention may further include a primary synchronization signal (PSS), a secondary synchronization signal

Receiving at least one of a secondary synchronization signal, a system information block, and a cell-specific reference signal (CRS).

Referring to FIG. 7, the terminal may include receiving additional configuration information for adding a carrier using the license-exempt frequency band to the secondary carrier (S710). For example, the terminal may receive additional configuration information including information necessary for adding a secondary carrier from the base station. Additional configuration information may be received via the primary carrier and received with higher layer signaling.

Further, the terminal may include a step of configuring the carrier in the license-unlicensed frequency band as a secondary carrier based on the additional configuration information (S720). For example, the terminal may further configure the terminal with a secondary carrier using the license-exempt frequency band using the received additional configuration information. That is, it is possible to configure or set a lower layer in the terminal for transmitting and receiving data and signals through the secondary carrier. If necessary, the secondary carrier can be set to receive only downlink data. In this case, the control signal and the response signal for the secondary carrier may be set to be transmitted and received via the primary carrier. Alternatively, the secondary carrier may be configured to transmit and receive both uplink and downlink data.

Thereafter, the terminal may receive the synchronization-related signal in a time interval occupied exclusively according to occupation reservation information (S730). For example, the UE can receive at least one of the above-mentioned PSS, SSS, SIB, and CRS in the corresponding time interval. Thereafter, when the synchronization is terminated in the time interval, the synchronization related signal is no longer received. Through this, the terminal can synchronize with the base station in the secondary carrier and receive system information and the like necessary for data reception.

In addition, the UE may receive the downlink data through the secondary carrier in a time period occupied exclusively according to the occupancy reservation information transmitted by the base station (S740). As described above, when the downlink data is received, the occupied reservation information can be transmitted by the base station. Conversely, when the terminal transmits uplink data, the terminal may generate and transmit occupancy reservation information. For example, occupancy reservation information may include at least one of time information and destination address information necessary for transmitting a response signal to downlink data. That is, the occupancy reservation information may include both the time resource expected to be used for transmitting the downlink data and the time resource necessary for the terminal to receive the downlink data and transmit the response signal. However, when the terminal is set to transmit the response signal to the primary carrier, the occupancy reservation information may include only information on the time resources required for transmitting the downlink data. The occupancy reservation information may further include destination address information, and the destination address information may be identification information of the base station or identification information of the WLAN equipment configured in the base station. The occupancy reservation information can be transmitted via the secondary carrier. On the other hand, the UE can receive downlink data in a time period exclusively occupied according to the occupancy reservation information and the synchronization related signal.

According to the present invention described above, there is an advantage that the LTE transmission efficiency can be maximized by utilizing the license-exempt band. In particular, any LTE equipment not equipped with any LTE-U LBT scheme that is expected to be standardized in the future can transmit and receive data using the license-free frequency band according to the above-described method. This provides an advantage of maximizing utilization of license-exempt frequency resources.

FIG. 8 and FIG. 9 show the configurations of the base station and the terminal in which the above-described present invention can be all performed. The base station and the terminal of the present invention will be briefly described again with reference to FIGS. 8 and 9. FIG.

8 is a diagram illustrating a base station configuration according to another embodiment of the present invention.

8, a base station 800 according to another embodiment of the present invention includes a transmitter 820 for transmitting additional configuration information for adding a carrier using a license-free frequency band as a secondary carrier to a terminal, And a control unit 810 for generating occupancy reservation information including information on a time interval of the license-exempt frequency band necessary for transmission.

In addition, the transmitter 820 can transmit the occupancy reservation information and transmit the downlink data through the secondary carrier according to the occupation reservation information. The time interval may refer to radio resources exclusively occupied by the BS for downlink data transmission. The occupancy reservation information may include at least one of time information and destination address information necessary for transmitting a response signal to the downlink data. The destination address information may be identification information of the base station. Or the destination address information may be the identification information of the WLAN equipment constituting the base station.

The transmitting unit 820 can transmit occupancy reservation information via the secondary carrier. The transmitter 820 may further transmit at least one of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a system information block and a cell-specific reference signal (CRS) within a time interval of the secondary carrier .

The receiving unit 830 can receive uplink data, signals, and the like from the terminal.

The transmitting unit 820 and the receiving unit 830 are used to transmit and receive signals, messages, and data necessary for performing the above-described present invention.

Meanwhile, the controller 810 configures a secondary carrier in the terminal using the license-exempt frequency band necessary for carrying out the present invention, occupies the license-exempt frequency band using the occupancy reservation information, and transmits the overall data And controls the operation of the base station 800.

9 is a diagram illustrating a configuration of a user terminal according to another embodiment of the present invention.

The user terminal 900 according to another embodiment of the present invention includes a receiving unit 930 that receives additional configuration information for adding a carrier using a license-free frequency band to a secondary carrier, And a control unit 910 that configures the carrier as a secondary carrier.

Also, the receiver 930 receives the downlink data through the secondary carrier in a time period exclusively occupied according to the occupancy reservation information transmitted by the base station. As described above, the time interval may refer to radio resources exclusively occupied by the base station for downlink data transmission. The occupancy reservation information may include at least one of time information and destination address information necessary for transmitting a response signal to the downlink data. The destination address information may be identification information of the base station. Or the destination address information may be the identification information of the WLAN equipment constituting the base station.

The receiver 930 may further receive at least one of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a system information block and a cell-specific reference signal (CRS) within a time interval of the secondary carrier have.

The transmitter 920 can transmit uplink data, signals, and the like to the base station. If necessary, the transmitter 920 may transmit occupancy reservation information for transmitting uplink data. In addition, the transmitting unit 920 and the receiving unit 930 are used to transmit / receive signals, messages, and data necessary for performing the above-described present invention to / from the base station.

The control unit 910 constitutes a secondary carrier using the license-exempt frequency band necessary for carrying out the present invention described above, occupies the license-exempt frequency band using occupancy reservation information, and transmits and receives data to and from the base station 900 ).

The standard content or standard documents referred to in the above-mentioned embodiments constitute a part of this specification, for the sake of simplicity of description of the specification. Therefore, it is to be understood that the content of the above standard content and portions of the standard documents are added to or contained in the scope of the present invention.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims

A method for a base station to transmit data,
Transmitting additional configuration information to the terminal for adding a carrier using the license-exempt frequency band to the secondary carrier;
Transmitting occupancy reservation information including information on a time interval of the license-exempt frequency band required for downlink data transmission; And
And transmitting the downlink data via the secondary carrier according to the occupancy reservation information.

The method according to claim 1,
The time interval may be,
And the base station is a radio resource exclusively occupied for the downlink data transmission.

The method according to claim 1,
The occupancy reservation information includes:
And time information and destination address information necessary for transmitting a response signal to the downlink data.

The method of claim 3,
The destination address information includes:
The identification information of the base station.

The method according to claim 1,
The occupancy reservation information includes:
And the second carrier is transmitted through the secondary carrier.

The method according to claim 1,
Prior to transmitting the downlink data,
Further comprising the step of transmitting at least one of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a system information block and a cell-specific reference signal (CRS) within a time interval of the secondary carrier.

In a method for a terminal to receive data,
Receiving additional configuration information for adding a carrier using the license-exempt frequency band to the secondary carrier;
Configuring a carrier in the license-exempt frequency band as a secondary carrier based on the additional configuration information; And
And receiving the downlink data via the secondary carrier in a time interval occupied exclusively according to occupancy reservation information transmitted by the base station.

8. The method of claim 7,
The occupancy reservation information includes:
And time information and destination address information necessary for transmitting a response signal to the downlink data.

9. The method of claim 8,
The destination address information includes:
The identification information of the base station.

8. The method of claim 7,
The occupancy reservation information includes:
Wherein the secondary carrier is received via the secondary carrier.

8. The method of claim 7,
Prior to the step of receiving the downlink data,
Further comprising receiving at least one of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a system information block, and a cell-specific reference signal (CRS) within a time interval of the secondary carrier.

A base station for transmitting data,
A transmission unit for transmitting to the terminal additional configuration information for adding a carrier using the license-exempt frequency band to the secondary carrier; And
And a controller for generating occupancy reservation information including information on a time interval of the license-exempt frequency band necessary for downlink data transmission,
The transmitter may further comprise:
Transmits the occupation reservation information,
And transmits the downlink data through the secondary carrier according to the occupation reservation information.

13. The method of claim 12,
The time interval may be,
Wherein the base station is a radio resource exclusively occupied by the base station for the downlink data transmission.

13. The method of claim 12,
The occupancy reservation information includes:
A time information required for transmitting a response signal to the downlink data, and destination address information.

15. The method of claim 14,
The destination address information includes:
And identification information of the base station.

13. The method of claim 12,
The occupancy reservation information includes:
And the secondary carrier is transmitted through the secondary carrier.

13. The method of claim 12,
The transmitter may further comprise:
Wherein at least one of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a system information block, and a cell-specific reference signal (CRS) is further transmitted within a time interval of the secondary carrier.

In a terminal that receives data,
A receiving unit for receiving additional configuration information for adding a carrier using the license-exempt frequency band to the secondary carrier; And
And a control unit configured to configure the carrier of the license-exempt frequency band as a secondary carrier based on the additional configuration information,
The receiver may further comprise:
And receiving the downlink data through the secondary carrier in a time interval occupied exclusively according to occupancy reservation information transmitted by the base station.

19. The method of claim 18,
The occupancy reservation information includes:
A time information required for transmitting a response signal to the downlink data, and destination address information.

20. The method of claim 19,
The destination address information includes:
The identification information of the base station.

19. The method of claim 18,
The occupancy reservation information includes:
And is received via the secondary carrier.

19. The method of claim 18,
The receiver may further comprise:
Further comprising at least one of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a system information block, and a cell-specific reference signal (CRS) within a time interval of the secondary carrier.