KR102279648B1 - Method and apparatus for channel occupancy in unlicensed band - Google Patents

Abstract

A method and apparatus for occupying a channel of an unlicensed band are provided through the steps of performing channel sensing for a channel, and broadcasting a reservation signal for the channel when the channel is empty after the end of the channel sensing.

Description

Channel occupancy method and apparatus in unlicensed band {Method and apparatus for channel occupancy in unlicensed band}

The present invention relates to a method and apparatus for occupying a channel in an unlicensed band.

Since the advent of 4G mobile communication, wireless traffic serviced through a mobile communication system has been increasing every year, and mobile communication operators are conducting research to increase the capacity of the mobile communication system. The easiest way to increase the capacity of a mobile communication system is to simultaneously transmit a lot of data by securing a large number of frequencies required for data transmission. However, since the frequency used in the mobile communication system is a licensed band frequency that can be used exclusively, the available frequency band is limited and the usage fee is high, so there is a problem that the frequency cannot be used as much as desired. As a solution to this problem, the 3rd generation partnership project (3GPP) is studying a method of providing a mobile communication service through a frequency of an unlicensed band that can be used at low cost or free of charge.

Unlicensed band frequency is a frequency band that anyone can use if they comply with a specific frequency band or regulatory requirements defined in a specific region, and are currently used in systems such as wireless fidelity (WiFi) or Bluetooth (Bluetooth). say frequency. Regulatory requirements are regulations that all devices in unlicensed bands must comply with in order to allow devices using the same unlicensed band frequency to use each other safely and fairly. For example, a device that intends to use an unlicensed band frequency checks whether other unlicensed band devices are using the frequency before transmitting data through the unlicensed band frequency, and if the frequency is not used by other unlicensed band devices data can only be transmitted.

However, since a mobile communication system such as an existing long term evolution (LTE) is a system designed to provide a mobile communication service using a frequency of a licensed band, if the current system is installed in an unlicensed band as it is, the The base station always occupies a part of the unlicensed band frequency, and accordingly, other unlicensed band devices may have a problem that the frequency cannot be used. Therefore, it is necessary to improve the structure and function of the current mobile communication system in consideration of the regulatory requirements to be observed in order to use the unlicensed band frequency. At this time, if many of the basic functions of the mobile communication system (eg, frame structure, resource allocation structure, etc.) are changed, the system development period and cost may increase, so the change in functions of the existing mobile communication system is minimized At the same time, there is a need for a wireless channel access method that complies with regulatory requirements and enables fair coexistence with other unlicensed band devices.

An object of the present invention is to provide a channel occupation method and apparatus that comply with the regulatory requirements of the unlicensed band and can coexist fairly with other existing unlicensed band devices.

According to an embodiment of the present invention, performing channel sensing on the first channel of the unlicensed band, and when the first channel is empty after the end of the channel sensing, broadcasting a reservation signal for the first channel A method for a base station to occupy a channel of an unlicensed band is provided, including.

The LAA base station according to an embodiment of the present invention can stably occupy the channel before data transmission is actually made by transmitting a reservation signal when occupying the channel of the unlicensed band through the CCA. In addition, it is possible to maximize the actual channel occupancy time through slot unit data transmission. In addition, when a plurality of unlicensed band carriers are operated, the LAA base station according to an embodiment of the present invention transmits data through one unlicensed band channel and performs channel sensing on another unlicensed band channel at the same time to perform channel state The carrier can be dynamically changed according to the

1 is a conceptual diagram illustrating an unlicensed band mobile communication system according to an embodiment of the present invention.
2 is a conceptual diagram illustrating a channel access method according to an embodiment of the present invention.
3 is a flowchart illustrating a channel access method according to an embodiment of the present invention.
4 is a conceptual diagram illustrating a channel access method per subframe according to an embodiment of the present invention.
5 is a conceptual diagram illustrating a channel occupation notification method according to an embodiment of the present invention.
6 is a conceptual diagram illustrating a dynamic carrier change method according to an embodiment of the present invention.
7 is a flowchart illustrating a method for changing a dynamic carrier according to an embodiment of the present invention.
8 is a block diagram illustrating a wireless communication system according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, a terminal is a mobile station (mobile station, MS), a mobile terminal (MT), an advanced mobile station (AMS), a high reliability mobile station (HR-MS) ), subscriber station (SS), portable subscriber station (PSS), access terminal (AT), user equipment (UE), machine type communication device (machine type communication device, MTC device) and the like, and may include all or some functions of MT, MS, AMS, HR-MS, SS, PSS, AT, UE, and the like.

In addition, the base station (base station, BS) is an advanced base station (advanced base station, ABS), a high reliability base station (high reliability base station, HR-BS), a Node B (node B), an advanced node B (evolved node B, eNodeB), an access point (AP), a radio access station (RAS), a base transceiver station (BTS), a mobile multihop relay (MMR)-BS, a relay serving as a base station station, RS), a relay node (RN) serving as a base station, an advanced relay station (ARS) serving as a base station, and a high reliability relay station (HR) serving as a base station -RS), small base station [femto base station (femoto BS), home node B (home node B, HNB), home eNodeB (HeNB), pico base station (pico BS), macro base station (macro BS), micro base station (micro BS) ), etc.], etc., may include all or part of the functions of ABS, NodeB, eNodeB, AP, RAS, BTS, MMR-BS, RS, RN, ARS, HR-RS, small base station, etc. there is.

1 is a conceptual diagram illustrating an unlicensed band mobile communication system according to an embodiment of the present invention.

Referring to FIG. 1 , a mobile communication system according to an embodiment of the present invention includes a mobile communication base station 110 , a license assisted access (LAA) base station 120, an access point (AP) ( 130), the mobile terminal 140, and includes an unlicensed band user 150.

The mobile communication base station 110 performs control of the terminal and data service provision through a licensed band frequency.

The LAA base station 120 provides a data service to the terminal through an unlicensed band frequency, and usually has a smaller coverage than the mobile communication base station 110 . The mobile communication base station 110 and the LAA base station 120 may be connected to each other through a wired backhaul or may be physically located at the same location. Also, depending on the network configuration, the mobile communication base station 110 and the LAA base station 120 may operate independently of each other, or the mobile communication base station 110 may control the LAA base station 120 . At this time, since only the mobile communication base station 110 has the control authority of the terminal, the mobile terminal 140 must always maintain a connection with the mobile communication base station 110 through the licensed band frequency, and A data service may be provided through carrier aggregation (CA) of a licensed band frequency and an unlicensed band frequency of the LAA base station 120 . In addition, the LAA base station 120 may provide both an uplink and a downlink data service or only a downlink data service according to a network configuration.

The unlicensed band user 150 and the access point 130 perform data communication through a frequency of the same band as the unlicensed band frequency used by the LAA base station 120 . Even in the same unlicensed frequency band, the frequency of a radio channel used for actual communication may be the same or different. When the same radio channel of the same unlicensed frequency band is used, problems of coexistence and interference between the LAA base station 120 and the unlicensed band user 150 and the access point 130 may occur.

2 is a conceptual diagram illustrating a channel access method according to an embodiment of the present invention, and FIG. 3 is a flowchart illustrating a channel access method according to an embodiment of the present invention.

Referring to FIG. 2 , the time length of the LAA frame according to an embodiment of the present invention may be the maximum occupancy time of the unlicensed band. The maximum occupancy time of the unlicensed band may depend on regional regulations, and in this case, the fixed length of the LAA frame may be changed. When the maximum occupancy time is increased, the number of subframes used for data transmission in the LAA frame is increased. Although the channel access method according to an embodiment of the present invention can be applied to both uplink and downlink data service or only to downlink data service, a case in which it is applied only to downlink data service will be described below as an example.

2, the LAA frame according to an embodiment of the present invention, a channel sensing (clear channel assessment, CCA) period, an extended channel sensing (Extended CCA, eCCA) period, a channel reservation (channel reservation) period, and Includes a transmission section.

Referring to FIG. 3 , the LAA base station according to an embodiment of the present invention performs CCA in order to determine whether a frequency channel is being used by another unlicensed band device prior to data transmission ( S301 ). In this case, the LAA base station may perform CCA through an energy detection method. For example, the LAA base station measures the energy of the radio channel during the channel sensing period and determines that the current radio channel is occupied by another device if the measured energy is higher than the preset criterion, and if the measured energy is lower than the preset criterion, it is determined that the current radio channel is occupied by another device. It may be determined that the current radio channel is empty.

As a result of the CCA, if it is determined that the channel is being used by another unlicensed band device (S302), the LAA base station performs eCCA (S303). The eCCA is the same as the CCA in that the purpose of the eCCA is to determine whether to use the channel, but unlike the CCA, in the eCCA, whether to use the channel is determined several times. For eCCA, the LAA base station may select an eCCA counter value within a predetermined range. Thereafter, the LAA base station decrements the eCCA counter value by 1 if the channel is empty by performing channel sensing. However, if the channel sensing result of the LAA base station is used by other unlicensed band devices, the channel sensing is performed again without decreasing the eCCA counter value. The LAA base station performs eCCA until the eCCA counter value becomes 0. After that, when the eCCA counter value becomes 0, the LAA base station starts transmitting a reservation signal according to the time when the eCCA is terminated (S304), and the data Transmission can be started (S305).

Alternatively, if it is determined that the channel is empty as a result of CCA, the LAA base station does not perform eCCA and starts transmission of a reservation signal according to the time when CCA is terminated (S304) and may start data transmission (S305).

In a mobile communication system, which is a reference system of the LAA system, data transmission may start and end based on a predetermined frame or subframe. Therefore, the LAA base station may not always start data transmission at the time CCA or eCCA is terminated. Referring to FIG. 2 , the time point at which eCCA is terminated in the first CCA is the midpoint of the subframe, and therefore, the LAA base station cannot start data transmission through the corresponding channel even though the corresponding channel is empty. In this case, if the LAA base station stops channel access to the boundary point of the next subframe, the channel may be occupied by other unlicensed band devices.

Therefore, the LAA base station according to an embodiment of the present invention broadcasts a reservation signal immediately after CCA or eCCA until data transmission is possible, so that the radio channel to be occupied by the LAA base station is not occupied by other unlicensed band devices. there is. At this time, the reservation signal is a signal containing enough energy to recognize that the radio channel is occupied by other unlicensed band devices, and any type of signal may be used. For example, signals including only energy, a synchronization signal of an existing LTE system for downlink synchronization, and a preamble for cell identification may be used as a reservation signal.

Referring to FIG. 2 , the LAA base station according to an embodiment of the present invention recognizes that the channel is empty at the time of the 7th OFDM symbol through CCA and eCCA in the first channel access. However, since the next subframe does not start immediately after eCCA, the reservation signal is transmitted until the start time of the next subframe. Thereafter, the LAA base station according to an embodiment of the present invention starts transmitting downlink data from the start time of the next subframe.

In a typical mobile communication system, the start and end of data transmission may be performed in units of subframes. Accordingly, in order to satisfy the limited channel occupancy time (eg, 4 ms), up to three subframes may be used for downlink data transmission after transmission of the reservation signal. However, at this time, since the actual channel occupancy time of the LAA base station is the time for transmitting the reservation signal (eg, 0.5 ms) and three subframe times (eg, 3 ms), the maximum channel occupancy time (in this case, 4 ms) ) is smaller than Therefore, as the end time of CCA or eCCA according to an embodiment of the present invention approaches immediately after the start time of a subframe, the difference between the actual channel occupation time and the maximum channel occupation time may increase.

4 is a conceptual diagram illustrating a channel access method per subframe according to an embodiment of the present invention.

Conventionally, according to a mobile communication system such as LTE, since the start and end of data transmission must occur at the boundary of the subframe, the reservation signal according to an embodiment of the present invention is transmitted from the channel occupancy time of the LAA base station to the next subframe. It can be transmitted up to the start time. In this case, since the reservation signal is not a signal used for data transmission of the user, but affects the maximum channel occupancy time (the effect of shortening the actual channel occupancy time), radio resources may be wasted. In addition, since data transmission must always be terminated at the boundary point of the subframe, the maximum channel occupancy time cannot be used efficiently and the efficiency of overall resource utilization may also be reduced.

Referring to FIG. 4 , in the case of the first channel access of the LAA base station, the reservation signal was transmitted for 7 OFDM symbols because the CCA (or eCCA) was terminated at the midpoint of the subframe. Accordingly, in this case, the actual channel occupation time for data transmission is 3 ms (ie, 3 subframes). In the case of the second channel access of the LAA base station, since the CCA (or eCCA) is terminated near the boundary of the subframe, the reservation signal transmitted until the boundary of the next subframe is not more than in the case of the first channel access. However, if the time from the channel occupancy time to the next subframe boundary is too short, the time for the LAA base station to prepare for downlink data transmission through scheduling is insufficient, and actually reserved until the next subframe boundary of the next subframe. There may be a case where it is necessary to transmit a signal, and more resources may be wasted. Therefore, in order to minimize resource waste, it is necessary to start and end data transmission based on a time unit shorter than a subframe. At this time, if the start and end of data transmission is performed in units of OFDM symbols, resource waste can be minimized, but the structure of the current mobile communication system needs to be changed a lot, which can lead to lower backward compatibility and increased product development and production costs. there is.

The LAA base station according to an embodiment of the present invention may start and end data transmission in units of slots corresponding to half the time length of a subframe. In this case, the start and end of data transmission may be performed in a special subframe of the LTE system. The LAA base station according to an embodiment of the present invention may use a downlink pilot time slot (DwPTS) included in a special subframe of the LTE system. DwPTS is included in a special subframe of a time division duplex (TDD) frame of the LTE system, and is located in the front part of the special subframe at the time of changing from downlink to uplink. The LAA base station according to an embodiment of the present invention can maximize the actual channel occupancy time by using the DwPTS at various positions of the subframe.

The LAA base station according to an embodiment of the present invention may determine the start time of data transmission as the first occurring time among the start time of the next subframe and the start time of the next slot. Referring to FIG. 2 , in the first channel access, a reservation signal is transmitted until the start time of the next subframe, and data transmission is also started in the next subframe. However, in the second channel access, data transmission may be started at the beginning of the next slot. Also, the end time of data transmission may be determined as a time point at which the actual channel occupation time is close to the maximum channel occupation time among the ending time of the next subframe and the ending time of the next slot. Therefore, the LAA base station and the LAA terminal according to an embodiment of the present invention can secure the actual channel occupancy time to be as close as possible to the maximum channel occupancy time. Also, when a reservation signal is additionally transmitted due to a time constraint due to scheduling, the reservation signal may be transmitted in units of slots instead of subframes.

5 is a conceptual diagram illustrating a channel occupation notification method according to an embodiment of the present invention.

The LAA base station according to an embodiment of the present invention may perform CCA (or eCCA) at any time or occupy a channel at any time. Therefore, for smooth data communication between the LAA base station and the terminal, the terminal needs to know when the LAA base station occupies a channel to transmit data. The terminal can know whether the LAA base station occupies the channel by detecting whether the channel is occupied or not by being notified of whether the channel is occupied by the base station of the licensed band.

When the terminal detects whether the channel is occupied, the terminal may continuously attempt to receive data on the corresponding channel and determine whether the channel is occupied by the LAA base station according to the success of data reception. When a specific channel is assigned to the secondary cell of the UE by the channel or carrier management procedure, the UE attempts to receive data in every subframe and determines whether a reservation signal or a control channel (eg, PDCCH) is included in the subframe. When the subframe includes a reservation signal or a control channel, the terminal may determine that the corresponding channel is occupied by the LAA base station.

However, when the terminal detects whether the channel is occupied, power consumption may increase because the terminal must continuously attempt to receive data in a subframe. In particular, when the channel load is high, the probability that the LAA base station succeeds in channel occupation is low, and consequently, the probability that the UE does not need to detect whether the channel is occupied increases the probability. Conversely, when the channel load is low, since the probability of success in channel occupation of the LAA base station is high, the terminal can recognize whether the channel is occupied without wasting much power. Therefore, depending on the channel load, the method of detecting channel occupancy by the terminal and the method of notifying the channel occupancy by the base station may be operated complementary to each other.

When the base station notifies the terminal whether the LAA base station occupies the channel, the base station may notify the terminal whether the LAA base station occupies the channel and start data reception if the LAA base station succeeds in channel occupation. Since the terminal uses the licensed band carrier as the primary carrier and the unlicensed band carrier as the secondary carrier, the terminal always receives control information (eg, PDCCH) transmitted from the licensed band carrier. Therefore, if the LAA base station succeeds in channel occupation after CCA (or eCCA), it transmits the control channel to the licensed band carrier by including information about the channel occupation in the control channel. The terminal receiving the control channel through the licensed band carrier may recognize the channel occupancy of the LAA base station and start data reception.

5, when the LAA base station succeeds in occupying the channel after CCA (or eCCA) in the unlicensed band, it transmits a reservation signal and transmits the control channel including the channel occupancy information through the licensed band carrier in the next subframe to the terminal. send. At this time, since the channel occupancy for the unlicensed band carrier must be maintained until the terminal decodes the control channel from the licensed band carrier and starts data reception, the LAA base station has a reservation signal for a predetermined number of symbols even after the start of the next subframe. to send

The terminal receives a control channel through a licensed band carrier, and if the received control channel includes channel occupancy information, it starts receiving data. The channel occupancy notification method by the base station has an advantage that it can minimize power consumption of the terminal compared to the case where the terminal directly recognizes whether the channel is occupied, and more reservations until the terminal decodes the control channel and starts receiving data The disadvantage is that the signal needs to be transmitted.

Meanwhile, the LAA base station according to another embodiment of the present invention may deliver the channel occupancy information to the terminal through a means other than the control channel. For example, the LAA base station according to another embodiment of the present invention may include a new parameter for notifying whether a channel is occupied in a downlink control information (DCI) format. Alternatively, the LAA base station may use a dedicated DCI for delivering channel occupancy information to the terminal. In this case, the LAA base station may use a dedicated DCI including only channel occupancy information without scheduling information. The dedicated DCI transmitted from the licensed band PCell may include a parameter indicating whether or not channels for all unlicensed band SCells supported by the corresponding PCell are occupied, and the dedicated DCI may be broadcast to all terminals included in the PCell. Accordingly, the length of the dedicated DCI may be limited to the maximum number of unlicensed band SCells supported by the licensed band PCell. For example, if the maximum number of unlicensed band SCells supported by the licensed band PCell is three, the length of the dedicated DCI may be fixed to 3 bits, and each bit may indicate whether the SCell corresponding to each bit occupies the channel (eg For example, 0: Channel not occupied, 1: Channel occupied).

Alternatively, the LAA base station according to another embodiment of the present invention may use a dedicated downlink control channel for transmitting channel occupancy information. In this case, channel occupancy may be notified through a dedicated control channel containing information of a fixed size, and the overhead or transmission method is similar to that of the dedicated DCI, but channel occupancy information is provided through the dedicated control channel rather than the PDCCH. can be transmitted.

6 is a conceptual diagram illustrating a dynamic carrier changing method according to an embodiment of the present invention, and FIG. 7 is a flowchart illustrating a dynamic carrier changing method according to an embodiment of the present invention.

Since the channel of the unlicensed frequency band cannot be used exclusively by a specific system and is shared by a plurality of unlicensed band devices, continuous data transmission may be impossible. At this time, if the channels of a plurality of available unlicensed bands are maximally utilized, continuity of data transmission can be maximally secured.

When a plurality of available unlicensed band carriers are allocated to the LAA terminal as SCell, the LAA base station selects a carrier that can currently be occupied among candidate carriers through CCA (or eCCA) and transmits data, and the terminal operates as the selected carrier. can change and receive data. Carrier selection and change may be performed for every channel access, but in order to minimize overhead that may occur due to carrier change, the carrier needs to be selected and changed in the medium/long term in consideration of the channel load of each channel.

Referring to FIG. 6 , the LAA base station according to an embodiment of the present invention performs CCA (or eCCA) on not only the unlicensed band carrier currently used for data transmission, but also other unlicensed band carriers, and two carriers of the unlicensed band. A carrier capable of occupying a channel is determined. When a carrier capable of channel occupation is selected, the LAA base station occupies the carrier by transmitting a reservation signal, and instructs the UE to change the carrier through the PDCCH transmitted through the licensed band carrier in the next subframe. After receiving the carrier change indication through the PDCCH, the UE immediately changes the operation carrier to the indicated carrier and starts receiving data through the indicated carrier.

Meanwhile, when the LAA base station performs normal channel access without changing the carrier, data transmission may start in the next subframe or the next slot after the LAA base station occupies the channel. However, in case of dynamic carrier change, since it takes time for the terminal to receive the PDCCH and change the carrier, the LAA base station continues to transmit the reservation signal until the carrier is changed in the terminal. Referring to FIG. 6 , both the length of the PDCCH and the length of time required to change the carrier of the UE are shown as the length of one OFDM symbol. In this case, even if the terminal completes the carrier change, since data transmission is possible at the start time of the subframe or the special subframe, the reservation signal needs to be continuously transmitted until the start time of the subframe or the special subframe.

The LAA base station according to an embodiment of the present invention transmits data through one unlicensed band carrier (first carrier), and continuously performs CCA (or eCCA) on another unlicensed band carrier (second carrier). Then, when it is determined that the channel occupation of the second carrier is possible, the LAA base station determines whether to occupy the channel of the second carrier in consideration of the remaining channel occupation time of the first carrier.

Referring to FIG. 7 , the LAA base station and the terminal are performing data transmission/reception through the first unlicensed band SCell (S701). And, during data transmission/reception, the LAA base station may perform CCA (or eCCA) on the channel of the second unlicensed band SCell (S702). If channel occupation is possible for the channel of the second unlicensed band SCell, the LAA base station determines whether to occupy the channel in consideration of the remaining channel occupation time of the first unlicensed band SCell (S703). If the remaining channel occupancy time of the first unlicensed band SCell is significant, the LAA base station gives up the channel occupancy (S704), and after a preset time elapses, CCA (or eCCA) is performed again on the channel of the second unlicensed band SCell. can do.

However, when the LAA base station determines to occupy the channel, the LAA base station occupies the unlicensed band channel of the second unlicensed band SCell by transmitting a reservation signal (S705). Then, the LAA base station transmits a control channel (eg, PDCCH) including a carrier change indication through the licensed band PCell (S706). Thereafter, when the terminal receiving the control channel through the licensed band PCell changes the operating carrier to the channel of the second unlicensed band SCell, the LAA base station and the terminal transmit and receive data through the channel of the second unlicensed band SCell (S707). In this case, the data transmission/reception operation in the second unlicensed band SCell is the same as in the case of the first unlicensed band SCell.

Meanwhile, the LAA base station continues to transmit the reservation signal to occupy the channel of the second unlicensed band SCell until the terminal receives the control channel and changes the operating channel to the channel of the second unlicensed band SCell. In addition, while data transmission/reception is performed through the second unlicensed band SCell, the LAA base station performs CCA (or eCCA) for the first unlicensed band SCell and monitors whether channel occupancy is possible for the channel of the first unlicensed band SCell.

The LAA base station according to an embodiment of the present invention may attempt to change a channel in every channel access or, if the load of the operating channel is not large, may try to change the channel in the medium/long term according to the load of the operating channel. In this case, the carrier change can be performed quickly and efficiently without exchanging messages between higher layers for carrier change.

As described above, the LAA base station according to an embodiment of the present invention can stably occupy the channel before data transmission is actually made by transmitting a reservation signal when occupying the channel of the unlicensed band through CCA. In addition, it is possible to maximize the actual channel occupancy time through slot unit data transmission. In addition, when a plurality of unlicensed band carriers are operated, the LAA base station according to an embodiment of the present invention transmits data through one unlicensed band channel and performs channel sensing on another unlicensed band channel at the same time to perform channel state The carrier can be dynamically changed according to the

8 is a block diagram illustrating a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 8 , a wireless communication system according to an embodiment of the present invention includes a base station 810 and a terminal 820 .

The base station 810 includes a processor 811 , a memory 812 , and a radio frequency unit (RF unit) 813 . The memory 812 may be connected to the processor 811 to store various information for driving the processor 811 or at least one program executed by the processor 811 . The wireless communication unit 813 may be connected to the processor 811 to transmit and receive wireless signals. The processor 811 may implement a function, process, or method proposed in an embodiment of the present invention. In this case, in the wireless communication system according to an embodiment of the present invention, the air interface protocol layer may be implemented by the processor 811 . The operation of the base station 810 according to an embodiment of the present invention may be implemented by the processor 811 .

The terminal 820 includes a processor 821 , a memory 822 , and a wireless communication unit 823 . The memory 822 may be connected to the processor 821 to store various information for driving the process 821 . The wireless communication unit 823 may be connected to the processor 821 to transmit and receive wireless signals. The processor 821 may implement a function, step, or method proposed in an embodiment of the present invention. In this case, in the wireless communication system according to an embodiment of the present invention, the air interface protocol layer may be implemented by the processor 821 . The operation of the terminal 820 according to an embodiment of the present invention may be implemented by the processor 821 .

In an embodiment of the present invention, the memory may be located inside or outside the processor, and the memory may be connected to the processor through various known means. The memory is a volatile or non-volatile storage medium of various types. For example, the memory may include a read-only memory (ROM) or a random access memory (RAM).

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improved forms of the present invention are also provided by those skilled in the art using the basic concept of the present invention as defined in the following claims. is within the scope of the right.

Claims (13)

A channel access method of a base station for an unlicensed band, comprising:
performing channel sensing for transmitting data through the unlicensed band;
determining whether the first carrier in the unlicensed band is occupied or empty based on the result of the channel sensing;
Broadcasting a signal for indicating carrier occupation when it is determined that the first carrier is empty;
transmitting the data to a user equipment (UE) using the first carrier after broadcasting the signal
terminating the data transmission and simultaneously performing channel sensing for a plurality of carriers of the unlicensed band; and
resuming transmission of the data to the UE using a second carrier in the unlicensed band.
A channel access method comprising a. In claim 1,
Terminating the transmission of the data in the last subframe of the frame or in a Downlink Pilot Time Slot (DwPTS) period
A channel access method further comprising a. In claim 2,
The last subframe is a ninth subframe of the frame. In claim 2,
The last subframe is a third subframe of the frame. In claim 1,
Transmitting a carrier indication of the second carrier to the UE through a licensed band
A channel access method further comprising a. In claim 1,
Performing the channel sensing step,
performing the channel sensing based on the energy search method
A channel access method comprising: In claim 1,
Determining whether the first carrier in the unlicensed band is occupied or empty based on the result of the channel sensing comprises:
comparing the measured energy of the signal transmitted on the first carrier with a preset threshold, and
determining that the first carrier is empty when the measured energy is less than the preset threshold
A channel access method comprising: As a method for a terminal to receive data from a base station through an unlicensed band,
Receiving a signal for instructing carrier occupancy with respect to the first carrier in the unlicensed band from the base station after the base station performs channel sensing;
receiving data using the first carrier from the base station after receiving the signal;
After the reception of the data using the first carrier is finished and the base station simultaneously performs channel sensing for a plurality of carriers in the unlicensed band, the base station instructs the carrier occupancy on the second carrier in the unlicensed band receiving a carrier indication for
subsequently receiving the data from the base station using the second carrier in the unlicensed band.
wherein the signal is received when it is determined that the first carrier in the unlicensed band is empty for a channel sensing duration. In claim 8,
The signal prevents other terminals from accessing the first carrier in the unlicensed band for a predetermined time interval, the data receiving method. In claim 8,
Terminating the reception of the data in the last subframe of the frame or in a Downlink Pilot Time Slot (DwPTS) period
A data receiving method further comprising a. In claim 10,
The last subframe is a ninth subframe of the frame. In claim 10,
The last subframe is a third subframe of the frame. In claim 8,
Receiving the carrier indication of the second carrier from the base station through a licensed band
A data receiving method further comprising a.

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