KR20170020236A - Operation method of communication node in network supporting licensed and unlicensed bands - Google Patents

Abstract

A method of operating a communication node in a network supporting licensed and license-exempt bands is disclosed. One embodiment of the present invention is a method for measuring a channel occupancy state, comprising the steps of measuring a received signal strength in a measurement interval within a license-exempt band, determining a channel occupancy state by comparing a measured received signal strength with a preset threshold value, And reporting the information to the base station. Thus, the performance of the wireless communication system can be improved.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of operating a communication node in a network supporting license and license-exempt bands,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to communication technologies supporting licensed and license-exempt bands, and more particularly to channel access technologies based on channel occupancy states in a license-exempt band.

With the development of information and communication technology, various wireless communication technologies are being developed. Wireless communication technologies are broadly classified into wireless communication technologies using a licensed band and wireless communication technologies using an unlicensed band (for example, an industrial scientific medical (ISM) band) . Since licenses are licensed exclusively to one operator, wireless communication technologies that use licensed bands can provide better reliability and better communication quality than wireless licensed technologies that use license-exempt bands.

(LTE), long term evolution (LTE) defined in 3GPP (Third Generation Partnership Project) standard, and the like, and a base station (NodeB, NB) and a user equipment Each can transmit and receive signals through the licensed band. A wireless local area network (WLAN) defined by the IEEE 802.11 standard, and an access point (AP) and a station (STA) supporting the WLAN are each a license-exempt band Lt; RTI ID = 0.0 > and / or < / RTI >

Recently, mobile traffic has been explosively increasing, and it is necessary to secure an additional license band to process the mobile traffic through the license band. However, astronomical costs may be incurred in order to secure additional license bands, as licensed bands are finite, and usually licensed bands can be secured through auctions in the frequency bands between operators. In order to solve this problem, it is possible to consider providing LTE services through the license-exempt band.

When LTE (or LTE-A, etc.) services are provided through the license-exempt band, coexistence with the communication nodes supporting the WLAN (e.g., access points, stations, etc.) is required. For coexistence in a license-exempt band, a communication node (e.g., base station, UE, etc.) supporting LTE (or LTE-A, etc.) may occupy the license-exempt band based on a LBT (listen before talk). For example, a communication node (e.g., a base station, a UE, etc.) supporting LTE (or LTE-A, etc.) may determine a contention window by performing a random backoff operation , It is possible to randomly select the backoff value within the determined contention window and occupy the license-exempted bandwidth when the status of the license-exclusion zone is idle for a time corresponding to the selected backoff value.

Here, the size of the contention window can be changed statically or dynamically. However, the procedure for changing the size of the contention window in the license-exempt band where LTE (or LTE-A, etc.) services are provided is not clearly defined. In addition, there is a problem that the size of the contention window is changed without considering the license-exempt band state.

Meanwhile, the technology as the background of the invention is intended to enhance understanding of the background of the invention, and may include contents that are not known to the person of ordinary skill in the art.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for measuring channel occupancy in a license-exempted band.

According to another aspect of the present invention, there is provided a method of operating a UE in a communication network, the method comprising: measuring a received signal strength in a measurement interval in a license-exempt band; comparing a measured received signal strength with a predetermined threshold Determining a channel occupancy state, and reporting to the base station information indicating the channel occupancy state.

Here, the channel occupancy state may be a ratio of an interval in which the measured received signal strength is greater than or equal to the predetermined threshold value, and a ratio of the measurement interval.

Here, the channel occupancy may be a ratio of the number of samples whose measured received signal strength is greater than or equal to the preset threshold value to the total number of samples within the measurement interval.

Herein, the information indicating the channel occupation state may be transmitted to the base station via the PUCCH or PUSCH.

Here, the method of operating the UE may further include receiving a message requesting measurement of a channel occupation state from the base station.

Here, the message may include information related to the periodicity of the measurement period of the received signal strength and the measurement start time.

Here, the message may further include information related to the measured channel frequency, the preset threshold value, and the length of the measurement period.

Here, the message may be an RRC message.

According to another aspect of the present invention, there is provided a method of operating a base station in a communication network, the method including generating a first message requesting measurement of a channel occupancy state, transmitting the first message to a UE, And a second message including information indicating a channel occupation state determined based on a result of comparison between a received signal strength measured in a measurement interval in the license-exempt band and a predetermined threshold in response to the first message, Lt; / RTI >

Here, the channel occupancy state may be a ratio of an interval in which the measured received signal strength is greater than or equal to the predetermined threshold value, and a ratio of the measurement interval.

Here, the channel occupancy may be a ratio of the number of samples whose measured received signal strength is greater than or equal to the preset threshold value to the total number of samples within the measurement interval.

Here, the first message may include information related to the periodicity of the measurement period of the received signal strength and the measurement start time.

Here, the first message may further include information related to the measured channel frequency, the preset threshold, and the length of the measurement period.

Here, the first message may be an RRC message.

Here, the second message may be received from the UE via a PUCCH or a PUSCH.

In order to achieve the above object, a UE supporting a license-exempt band according to an embodiment of the present invention includes a processor and a memory storing at least one command executed by the processor, Determines a channel occupied state by comparing the measured received signal strength with a preset threshold value, and reports information indicating the occupied channel state to the base station.

Here, the channel occupancy state may be a ratio of an interval in which the measured received signal strength is greater than or equal to the predetermined threshold value, and a ratio of the measurement interval.

Here, the channel occupancy may be a ratio of the number of samples whose measured received signal strength is greater than or equal to the preset threshold value to the total number of samples within the measurement interval.

Here, the at least one command may be further executed to receive a message requesting measurement of a channel occupancy state from the base station.

Here, the message may include information related to the measured channel frequency, the predetermined threshold, the length of the measurement period, the periodicity of the measurement period of the received signal strength, and the measurement start time.

According to the present invention, a communication node supporting LBT can measure a channel occupation state (e.g., channel congestion) in a license-exempt band. The channel occupancy state can be measured based on the number of communication nodes operating on the channel, received signal strength, and the like. The channel occupancy state may be expressed in a simple form, and information indicating the channel occupancy state may be shared among communication nodes (e.g., base station-UE or base station-base station). For example, the channel occupancy state may be represented by a relatively small number of bits (e.g., 3 bits, 4 bits, etc.), thereby reducing the overhead in the transmission and reception procedures of information indicating the channel occupancy state .

Also, the communication node supporting the LBT can determine the size of the contention window based on the channel occupation state, and can perform communication based on the size of the contention window determined. In addition, the communication node supporting the LBT can select a channel based on the channel occupation state, and can perform communication in the selected channel.

Also, the hidden node problem can be solved based on the channel occupation state.

1 is a conceptual diagram showing a first embodiment of a wireless communication network.
2 is a conceptual diagram showing a second embodiment of a wireless communication network.
3 is a conceptual diagram showing a third embodiment of a wireless communication network.
4 is a conceptual diagram showing a fourth embodiment of a wireless communication network.
5 is a block diagram showing an embodiment of a communication node constituting a wireless communication network.
6 is a flowchart showing a channel access method based on the channel occupation state.
7 is a timing diagram illustrating a first embodiment for determining a channel occupancy state of a license-exempt band according to the present invention.
8 is a timing diagram illustrating a second embodiment for determining the channel occupancy state of the license-exempt band according to the present invention.
9 is a timing chart showing an example of sampling during a measurement interval.
10 is a timing diagram illustrating a third embodiment for determining the channel occupancy state of the license-exempt band according to the present invention.
11 is a flowchart showing a method of changing a contention window size based on a change amount of a channel occupation state.
12 is a flowchart showing a method of changing the size of the contention window based on the channel occupation state.
13 is a flowchart showing a method of activating a license-exempted band channel based on a channel occupation state.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

In the following, a wireless communication network to which embodiments according to the present invention are applied will be described. The wireless communication network to which the embodiments according to the present invention are applied is not limited to the following description, and the embodiments according to the present invention can be applied to various wireless communication networks.

1 is a conceptual diagram showing a first embodiment of a wireless communication network.

Referring to FIG. 1, a first base station 110 may be coupled to a base station 110, such as a cellular communication (e.g., long term evolution (LTE) U (unlicensed), etc.). The first base station 110 may be a multiple input multiple output (MIMO), a single user (MIMO), a multiuser (MU), a massive MIMO, Carrier aggregation (CA), and so on. The first base station may operate in a licensed band F1 and form a macro cell. The first base station 110 may be coupled to another base station (e.g., the second base station 120, the third base station 130, etc.) via an ideal backhaul or a non-idle backhaul.

The second base station 120 may be located within the coverage of the first base station 110. The second base station 120 may operate in an unlicensed band F3 and may form a small cell. The third base station 130 may be located within the coverage of the first base station 110. The third base station 130 may operate in the license-exempt band F3 and may form a small cell. Each of the second base station 120 and the third base station 130 may support a wireless local area network (WLAN) defined in the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. Each of the user equipment (not shown) connected to the first base station 110 and the first base station 110 transmits and receives signals through a carrier aggregation CA between the license band F1 and the license- can do.

2 is a conceptual diagram showing a second embodiment of a wireless communication network.

Referring to FIG. 2, each of the first base station 210 and the second base station 220 may support cellular communication (e.g., LTE, LTE-A, LTE-U, etc. defined in the 3GPP standard). Each of the first base station 210 and the second base station 220 may support MIMO (e.g. SU-MIMO, MU-MIMO, large-scale MIMO, etc.), CoMP, carrier aggregation (CA) Each of the first base station 210 and the second base station 220 may operate in the license band F1 and form a small cell. Each of the first base station 210 and the second base station 220 may be located within the coverage of the base station forming the macrocell. The first base station 210 may be connected to the third base station 230 via an idle backhaul or a non-idle backhaul. The second base station 220 may be coupled to the fourth base station 240 via an idle backhaul or a non-idle backhaul.

The third base station 230 may be located within the coverage of the first base station 210. The third base station 230 may operate in the license-exempt band F3 and may form a small cell. The fourth base station 240 may be located within the coverage of the second base station 220. The fourth base station 240 may operate in the license-exempt band F3 and form a small cell. Each of the third base station 230 and the fourth base station 240 may support a WLAN defined by the IEEE 802.11 standard. Each of the UEs connected to the first base station 210 and the first base station 210 and the UEs connected to the second base station 220 and the second base station 220 are connected to a carrier between the license band F1 and the license- Signals can be sent and received via Aggregation (CA).

3 is a conceptual diagram showing a third embodiment of a wireless communication network.

3, each of the first base station 310, the second base station 320, and the third base station 330 includes a base station (e.g., a base station) ). Each of the first base station 310, the second base station 320 and the third base station 330 may be a mobile station such as MIMO (e.g. SU-MIMO, MU-MIMO, large-scale MIMO etc.), CoMP, carrier aggregation . The first base station 310 may operate in the license band F1 and may form macro cells. The first base station 310 may be coupled to another base station (e.g., the second base station 320, the third base station 330, etc.) through an idle backhaul or a non-idle backhaul. The second base station 320 may be located within the coverage of the first base station 310. The second base station 320 may operate in the license band F1 and form a small cell. The third base station 330 may be located within the coverage of the first base station 310. The third base station 330 may operate in the license band F1 and form a small cell.

The second base station 320 may be coupled to the fourth base station 340 via an idle backhaul or a non-idle backhaul. The fourth base station 340 may be located within the coverage of the second base station 320. The fourth base station 340 can operate in the license-exempt band F3 and form a small cell. The third base station 330 may be connected to the fifth base station 350 via an idle backhaul or a non-idle backhaul. The fifth base station 350 may be located within the coverage of the third base station 330. The fifth base station 350 may operate in the license-exempt band F3 and may form a small cell. Each of the fourth base station 340 and the fifth base station 350 may support the WLAN defined in the IEEE 802.11 standard.

(Not shown) connected to the first base station 310, a UE (not shown) connected to the first base station 310, a second base station 320, a UE (not shown) connected to the second base station 320, And the UEs (not shown) connected to the third base station 330 can transmit and receive signals through the carrier aggregation CA between the license band F1 and the license-exempt band F3.

4 is a conceptual diagram showing a fourth embodiment of a wireless communication network.

4, each of the first base station 410, the second base station 420, and the third base station 430 includes a base station (not shown) such as a cellular communication (e.g., LTE, LTE-A, LTE- ). Each of the first base station 410, the second base station 420 and the third base station 430 may be a mobile station such as MIMO (e.g. SU-MIMO, MU-MIMO, large-scale MIMO etc.), CoMP, carrier aggregation . The first base station 410 may operate in the license band F1 and may form macro cells. The first base station 410 may be coupled to another base station (e.g., the second base station 420, the third base station 430, etc.) via an idle backhaul or a non-idle backhaul. The second base station 420 may be located within the coverage of the first base station 410. The second base station 420 may operate in the license band F2 and may form a small cell. The third base station 430 may be located within the coverage of the first base station 410. The third base station 430 may operate in the license band F2 and may form a small cell. Each of the second base station 420 and the third base station 430 may operate in a license band F2 different from the license band F1 in which the first base station 410 operates.

The second base station 420 may be coupled to the fourth base station 440 via an idle backhaul or a non-idle backhaul. The fourth base station 440 may be located within the coverage of the second base station 420. The fourth base station 440 may operate in the license-exempt band F3 and may form a small cell. The third base station 430 may be connected to the fifth base station 450 through an idle backhaul or a non-idle backhaul. The fifth base station 450 may be located within the coverage of the third base station 430. The fifth base station 450 may operate in the license-exempt band F3 and form a small cell. Each of the fourth base station 440 and the fifth base station 450 may support a WLAN defined in the IEEE 802.11 standard.

Each of the UEs (not shown) connected to the first base station 410 and the first base station 410 can transmit and receive signals through the carrier aggregation CA between the license band F1 and the license-exempt band F3. (Not shown) connected to the second base station 420, the UE (not shown) connected to the second base station 420, the third base station 430 and the third base station 430, And a carrier aggregation (CA) between the license-exempt zone (F3) and the license-exempt zone (F3).

A communication node (i.e., a base station, a UE, etc.) constituting the wireless communication network described above can transmit signals based on a listen before talk (LBT) procedure in an unlicensed band. That is, the communication node can determine the occupancy state of the license-exempt band by performing an energy detection operation. The communication node may transmit a signal when the license-exempt band is determined to be in an idle state. At this time, the communication node can transmit a signal when the license-exempt band is idle during a contention window according to a random backoff operation. On the other hand, the communication node may not transmit a signal when the license-exempt band is judged to be in a busy state.

Alternatively, the communication node may send a signal based on a carrier sensing adaptive transmission (CSAT) procedure. That is, the communication node can transmit a signal based on a preset duty cycle. The communication node may transmit a signal if the current duty cycle is a duty cycle assigned for a communication node that supports cellular communication. On the other hand, the communication node may not transmit a signal if the current duty cycle is the duty cycle allocated for the communication node supporting communications other than cellular communication (e.g., WLAN, etc.). The duty cycle can be adaptively determined based on the number of communication nodes supporting the WLAN existing in the license-exempt band, the usage state of the license-exempt band, and the like.

The communication node may perform discontinuous transmission in the license-exempt band. For example, if the maximum transmission duration or the maximum channel occupancy time (maximum COT) is set in the license-exempt band, the communication node can transmit signals within the maximum transmission period, If all the signals can not be transmitted within the maximum transmission period, the remaining signals can be transmitted in the next maximum transmission period. In addition, the communication node may select a carrier with relatively small interference in the license-exempt band and may operate on the selected carrier. In addition, the communication node may adjust the transmission power to reduce interference to other communication nodes when transmitting signals in the license-exempt band.

Meanwhile, the communication node may be a communication protocol based on a code division multiple access (CDMA) communication protocol, a communication protocol based on a wideband CDMA (WCDMA), a communication protocol based on a time division multiple access (TDMA), a communication protocol based on a frequency division multiple access , An SC (single carrier) -FDMA communication protocol, an orthogonal frequency division multiplexing (OFDM) based communication protocol, and an orthogonal frequency division multiple access (OFDMA) based communication protocol.

Among the communication nodes, a base station includes a Node B (NB), an evolved Node B (eNB), a base transceiver station (BTS), a radio base station, a radio transceiver, , AP), an access node, and the like. Among the communication nodes, a UE may be a terminal, an access terminal, a mobile terminal, a station, a subscriber station, a portable subscriber station, a mobile station ), A node, a device, and the like. The communication node may have the following structure.

5 is a block diagram showing an embodiment of a communication node constituting a wireless communication network.

Referring to FIG. 5, the communication node 500 may include at least one processor 510, a memory 520, and a transceiver 530 connected to a network to perform communication. In addition, the communication node 500 may further include an input interface device 540, an output interface device 550, a storage device 560, and the like. Each of the components included in the communication node 500 may be connected by a bus 570 to communicate with each other.

The processor 510 may execute a program command stored in at least one of the memory 520 and the storage device 560. The processor 510 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods in accordance with embodiments of the present invention are performed. Each of the memory 520 and the storage device 560 may be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 520 may be comprised of at least one of read only memory (ROM) and random access memory (RAM).

Next, methods of operating the communication node in the wireless communication network will be described. Even if a method (e.g., transmission or reception of a signal) to be performed at the first communication node among the communication nodes is described, the corresponding second communication node is controlled by a method corresponding to the method performed at the first communication node For example, receiving or transmitting a signal). That is, when the operation of the UE is described, the corresponding base station can perform an operation corresponding to the operation of the UE. Conversely, when the operation of the base station is described, the corresponding UE can perform an operation corresponding to the operation of the base station.

On the other hand, carrier aggregation can be applied between cells in the license-exempt band and cells in the license band. The configuration, add, modify, or release of a cell in the license-exempt zone may be accomplished by radio resource control (RRC) signaling (e.g., an RRConnectionReconfiguration message Reception procedure of the base station). The RRC message may be transmitted from the cell in the license band to the UE. The RRC message may include information necessary for operation and operation of the cell in the license-exempt band.

The initial state of the unlicensed secondary cell constructed or added may be in a deactivation state. When the state of the license-exempted secondary cell is switched from the inactive state to the activation state, communication can be performed in the license-exempted secondary cell.

Unlike the cell in the license band, the period in which the signal can be continuously transmitted in the cell of the license-exempt band can be limited within the maximum transmission period. Further, when a signal is transmitted based on the LBT, a signal can be transmitted when transmission of another communication node is completed. Transmission of communication nodes supporting LTE (or LTE-A, etc.) may have aperiodic, discontinuous, opportunistic characteristics when LTE (or LTE-A, etc.) services are provided through the license-exempt band. Based on this feature, a signal transmitted continuously by a communication node supporting LTE (or LTE-A, etc.) for a certain time in the license-exempt band may be referred to as a " license-exempt band burst ".

In addition, a channel defined in the license band (for example, a physical control format indicator channel (PCFICH), a physical hybrid-ARQ indicator channel (PHICH), a physical downlink control channel (PDCCH) channel, a physical multicast channel (PMCH), a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH), etc.) and a signal (for example, a synchronization signal, a reference signal, A contiguous set of subframes consisting of one or more combinations may be transmitted over the license-exempt band. In this case, the transmission of subframes may be referred to as "license-exempt band transmission ".

The frames used for transmission in the license-exempt band can be classified into a downlink license-exempt band burst frame, an uplink license-exempt band burst frame, and a downward / upward license-exclusion band burst frame. The DL-license-exempt band burst frame may include a sub-frame to which "license-exempt band transmission" is applied, and may further include a "license-exempt band signal ". Within the DL-license-exempt band burst frame, the "license-exempt band signal" may be located before the sub-frame to which the "license-exempt band transmission" applies. The "license-exempt band signal" is used to match the timing (or OFDM symbol timing) of the subframe to which the "license-exempt band transmission" is applied and the timing (or OFDM symbol timing) of the subframe in the license band Lt; / RTI > In addition, a "license-exempt band signal" may be used for automatic gain control (AGC), synchronization acquisition, channel estimation, etc. required for reception of data based on "license-exempt band transmission".

The subframe to which the "license-exempt band transmission" is applied can be set within the maximum transmission interval (or the maximum occupation interval). That is, the number of subframes to which the "license-exempt band transmission" is applied can be set based on the maximum transmission interval (or the maximum occupation interval). At this time, the number of subframes to which the " license-exempt band transmission "is applied can be set in consideration of the" license-exempt band signal ". In the license-exempt band, the maximum transmission interval (or maximum occupancy interval) may be known via RRC signaling. The UE can confirm the start time of the "license-exempt band burst" by detecting the PDCCH (or EPDCCH) or "license-exempt band signal ". The actual occupancy time by the subframe to which the "license-exempt band burst" or "license-exempt band transmission" is applied may be known via the "license-exempted band signal"

A "license-exempt band signal" may include information (or sequence) indicating the number (or time) of subframes used for "license-exempt band burst" or "license-exempt band transmission". Alternatively, information (or sequence) indicating the number (or time) of subframes used for "license-exempt band burst" or "license-exempt band transmission" may be transmitted via the PHICH.

In the license-exempt band, transmission of HARQ-related information on the uplink can be performed asynchronously differently from the license band. Accordingly, the RV and the HARQ process number can be transmitted on the PDCCH (or EPDCCH) instead of the PHICH. In this case, the PHICH may be used for the transmission of other information. For example, information (or sequence) indicating the number (or time) of subframes used for "license-exempt band burst" or "license-exempt band transmission" may be transmitted via the PHICH.

On the other hand, when the license-exempted band is exclusively used by one wireless communication network, the channel occupancy state (e.g., channel congestion) can be measured relatively easily. On the other hand, if the channel of the license-exempt band is shared by a plurality of wireless communication networks, the measurement of the channel occupancy state may be relatively difficult. For example, in a WLAN defined in the IEEE 802.11 standard, a communication node may determine that the channel occupancy state is busy if it fails to receive an ACK (acknowledge) frame for the transmitted data frame. In this case, the communication node may increase the size of the contention window. However, according to this method, the channel occupation state may not be accurately measured.

Next, a method of measuring the channel occupancy state based on the received signal strength (for example, RSSI (received signal strength indication), a channel access method based on the measured channel occupancy state, etc. will be described.

6 is a flowchart showing a channel access method based on the channel occupation state.

Referring to FIG. 6, the base station and the UE may form the wireless communication network described with reference to FIGS. 1 to 4, and may support the license band and the license-exempt band. The base station may support carrier aggregation. The base station and the UE may be configured the same or similar to the communication node 500 described with reference to Fig. The timing of the subframe (or slot, OFDM symbol, etc.) of the license band may be the same as the timing of the subframe (or slot, OFDM symbol, etc.) of the license-exempt band.

The base station may transmit a first message requesting measurement of the channel occupancy state to the UE (S600). The first message may be sent to the UE via an upper layer protocol (e.g., radio resource control (RRC) signaling). Alternatively, the first message may be transmitted to the UE via the PDCCH, EPDCCH or PDSCH in the license band or the license-exempt band. The first message may request a measurement of the channel occupancy state for an unlicensed band cell that is active or deactivated.

The first message may include measurement interval information, measured channel frequency information (i.e., frequency information for measurement), a predetermined threshold value (i.e., a threshold value for received signal strength), periodicity information of a measurement period, (E.g., sampling interval, number of samples (for example, the number of samples in a measurement interval), etc.), and the like, and the like. have. Here, the measurement start time information may be an offset indicating a start time of measurement of the channel occupancy state.

The UE may receive a first message requesting measurement of the channel occupancy state from the base station. If the first message is received, the UE may measure the channel occupation state based on the information included in the first message (S610). The UE may measure the channel occupancy state using a continuous or non-continuous scheme (i.e., discrete). The method of measuring the channel occupancy state based on the continuous scheme may be as follows.

Method of measuring channel occupancy based on continuous method

The UE can check the measurement interval based on the information included in the first message. That is, when the measurement interval information is included in the first message, the UE can check the measurement period of the channel occupation state based on the first message. If the first message includes the periodicity information of the measurement period and the measurement start time information (i.e., the measurement period information is not included in the first message), the UE determines the measurement period based on the periodicity information of the measurement period and the measurement start time information The measurement period of the channel occupation state can be confirmed. In addition, the UE may determine that the measurement of the channel occupancy state is performed in the channel indicated by the frequency information included in the first message.

The UE may measure the received signal strength (e.g., RSSI) in the measurement period of the license-exempt band. If the license-exempted band cell is active, the signal transmitted from the base station may be excluded from the measurement target. The UE may compare the measured received signal strength with a predetermined threshold value. The UE may determine that the license-exempted band is in the busy state in a period in which the measured received signal strength is equal to or greater than a preset threshold value. On the other hand, the UE can determine that the license-exempt band is idle in a period in which the measured received signal strength is less than a predetermined threshold value. The UE can determine the channel occupancy state based on the state of the license-exempt band as follows.

7 is a timing diagram illustrating a first embodiment for determining a channel occupancy state of a license-exempt band according to the present invention.

)중에서

및

에서 비면허 대역이 비지 상태인 것으로 판단할 수 있고, 측정 구간(

) 중에서

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외의 영역에서 비면허 대역이 아이들 상태인 것으로 판단할 수 있다. UE는 아래 수학식 1을 기초로 채널 점유 상태를 결정할 수 있다. 즉, 채널 점유 상태는 측정된 수신 신호 세기가 상기 미리 설정된 임계값 이상인 구간과 상기 측정 구간의 비율일 수 있다.Referring to FIG. 7,

)Between

And

It can be judged that the license-exempt band is busy, and the measurement period

) Between

And

It can be determined that the license-exempt band is in the idle state. The UE can determine the channel occupation state based on Equation (1) below. That is, the channel occupancy state may be a ratio of the interval in which the measured received signal strength is greater than or equal to the preset threshold value to the measurement interval.

On the other hand, the UE can determine the channel occupation state using a plurality of preset threshold values as follows.

8 is a timing diagram illustrating a second embodiment for determining the channel occupancy state of the license-exempt band according to the present invention.

) 중에서

,

및

에서 비면허 대역이 비지 상태인 것으로 판단할 수 있고, 측정 구간(

) 중에서

에서 비면허 대역이 아이들 상태인 것으로 판단할 수 있다. UE는 아래 수학식 2를 기초로 채널 점유 상태를 결정할 수 있다.Referring to FIG. 8, when a preset first threshold value is used,

) Between

,

And

It can be judged that the license-exempt band is busy, and the measurement period

) Between

It can be determined that the license-exempt band is in the idle state. The UE can determine the channel occupation state based on Equation (2) below.

) 중에서

에서 비면허 대역이 비지 상태인 것으로 판단할 수 있고, 측정 구간(

) 중에서

,

및

에서 비면허 대역이 아이들 상태인 것으로 판단할 수 있다. UE는 아래 수학식 3을 기초로 채널 점유 상태를 결정할 수 있다.If a preset second threshold is used,

) Between

It can be judged that the license-exempt band is busy, and the measurement period

) Between

,

And

It can be determined that the license-exempt band is in the idle state. The UE can determine the channel occupation state based on Equation (3) below.

Referring again to FIG. 6, the method of measuring the channel occupancy state based on the non-continuous scheme may be as follows.

Method of measuring channel occupancy based on non-continuous method

The UE can check the measurement interval based on the information included in the first message. That is, when the measurement interval information is included in the first message, the UE can check the measurement period of the channel occupation state based on the first message. If the first message includes the periodicity information of the measurement period and the measurement start time information (i.e., the measurement period information is not included in the first message), the UE determines the measurement period based on the periodicity information of the measurement period and the measurement start time information The measurement period of the channel occupation state can be estimated. In addition, the UE may determine that the measurement of the channel occupancy state is performed in the channel indicated by the frequency information included in the first message. In addition, the UE can check the number of samples (or the sampling interval) in the measurement interval based on the sample-related information included in the first message. Sampling of the measured signal strength can be performed as follows.

9 is a timing chart showing an example of sampling during a measurement interval.

은 측정 구간의 길이를 의미할 수 있고,

은 측정 구간 내의 전체 샘플 개수를 의미할 수 있다.Referring to FIG. 9, there may be nine sampling points within a measurement interval. Thus, the UE can measure the received signal strength at nine sampling points within the measurement interval. Meanwhile, the sample-related information included in the first message may indicate the number of samples or the sampling interval. If the sample-related information indicates the number of samples, the UE can check the sampling interval based on Equation (4) below. Alternatively, when the sample-related information indicates the sampling interval, the UE can check the number of samples based on Equation (4) below. In Equation 4,

May denote the length of the measurement interval,

May refer to the total number of samples in the measurement interval.

Referring again to FIG. 6, the UE may measure a received signal strength (for example, RSSI) at a sampling time in a measurement period of the license-exempt band. If the license-exempted band cell is active, the signal transmitted from the base station may be excluded from the measurement target. The UE may compare the measured received signal strength with a predetermined threshold value. The UE may determine that the license-exempt band is in the busy state at the sampling time when the measured received signal strength is equal to or greater than a preset threshold value. On the other hand, the UE may determine that the license-exempt band is idle at the sampling time when the measured received signal strength is less than a preset threshold value. The UE can determine the channel occupancy state based on the state of the license-exempt band as follows.

10 is a timing diagram illustrating a third embodiment for determining the channel occupancy state of the license-exempt band according to the present invention.

) 중

및

내의 샘플링 시점들에서 비면허 대역이 비지 상태인 것으로 판단할 수 있고, 측정 구간(

) 중에서

및

외의 영역 내의 샘플링 시점들에서 비면허 대역이 아이들 상태인 것으로 판단할 수 있다. 이 경우, UE는 아래 수학식 5를 기초로 채널 점유 상태를 결정할 수 있다. 즉, 채널 점유 상태는 측정된 수신 신호 세기가 상기 미리 설정된 임계값 이상인 샘플 개수와 상기 측정 구간 내의 전체 샘플 개수의 비율일 수 있다.Referring to FIG. 10,

) Of

And

It can be determined that the license-exempt band is in the busy state at the sampling points in the measurement period

) Between

And

It can be determined that the license-exempt band is in the idle state at the sampling points in the area outside the area. In this case, the UE can determine the channel occupation state based on Equation (5) below. That is, the channel occupancy state may be a ratio of the number of samples whose measured received signal strength is greater than or equal to the preset threshold value to the total number of samples within the measurement interval.

은 측정 구간(

) 내의 전체 샘플 개수를 지시할 수 있다. 예를 들어,

은 9일 수 있다.

는 비면허 대역이 비지 상태인 샘플링 시점의 개수를 지시할 수 있다. 예를 들어,

는 3일 수 있다.here,

Is the measurement interval

≪ / RTI > E.g,

Lt; / RTI >

May indicate the number of sampling points at which the license-exempt band is busy. E.g,

Can be three.

Referring back to FIG. 6, in step S620, the UE may transmit a second message including information indicating a channel occupation state to the base station in response to the first message. The second message may be transmitted over the license band or the license-exempt band. The second message may be sent in response to the RRC message. Alternatively, the second message may be transmitted to the base station via the PUCCH or PUSCH.

The information indicating the channel occupancy state can be represented by an index. For example, a channel occupancy state (e.g., a percent value for a channel occupancy state) may be quantized (e.g., linearly) or unequally (e.g., non-linearly) quantized, and the index can indicate the quantized channel occupancy state. For example, an index may be represented by three bits as shown in Table 1 below. The channel occupancy state in Table 1 below may indicate a percentage value for the channel occupancy state determined based on Equation 1, 2, 3 or 5. [

Alternatively, the index can be represented by 4 bits as shown in Table 2 below. The channel occupancy state in Table 2 below may indicate a percentage value for the channel occupancy state determined based on Equation 1, 2, 3 or 5. [

Referring back to FIG. 6, the BS can receive the second message from the UE and change the size of the contention window based on the information indicating the channel occupation state included in the second message (S630). For example, if the channel occupation state is equal to or greater than a preset threshold value, the base station can increase the size of the contention window. On the other hand, if the channel occupancy state is less than a predetermined threshold, the base station can maintain, initialize, or reduce the size of the contention window.

Alternatively, the base station may change the size of the contention window based on the amount of change between the previous channel occupied state and the current channel occupied state. The method of changing the contention window size based on the change amount between the previous channel occupied state and the current channel occupied state may be as follows.

11 is a flowchart showing a method of changing a contention window size based on a change amount of a channel occupation state.

Referring to FIG. 11, the base station can calculate the increase amount of the current channel occupation state with respect to the previous channel occupation state, and compare the calculated increase amount with the preset first threshold value (S631). If the calculated amount of increase is larger than the preset first threshold value, the base station may increase the size of the contention window (S632).

If the calculated increase amount is less than or equal to the preset first threshold value, the base station can calculate the decrease amount of the current channel occupation state with respect to the previous channel occupation state, and compare the calculated decrease amount with the preset second threshold value (S633). If the calculated amount of decrease is larger than the preset second threshold value, the base station may decrease or initialize the size of the contention window (S634). If the calculated amount of decrease is less than or equal to the predetermined second threshold value, the base station can maintain the size of the contention window (S635).

Referring back to FIG. 6, the base station can perform communication in the license-exempt band based on the size of the changed contention window (S640). For example, the base station may select a backoff value within the changed contention window and may transmit the signal over the license-only bandwidth if the license-exclusion zone is idle for a time corresponding to the backoff value. Meanwhile, the BS can inform the UE of the size of the changed contention window. For example, the size of the changed contention window may be transmitted via an RRC message or downlink control information (DCI).

12 is a flowchart showing a method of changing the size of the contention window based on the channel occupation state.

Referring to FIG. 12, the first base station and the second base station can form the wireless communication network described with reference to FIGS. 1 to 4, and can support the license band and the license-exempt band. The first base station and the second base station may support carrier aggregation. The first base station and the second base station may be configured the same or similar to the communication node 500 described with reference to Fig. The timing of the subframe (or slot, OFDM symbol, etc.) of the license band may be the same as the timing of the subframe (or slot, OFDM symbol, etc.) of the license-exempt band.

The first base station may transmit a first message requesting measurement of the channel occupation state to the second base station (S1200). The first message may be sent to the second base station based on an upper layer protocol or an X2 interface. The first message may be the same as the first message described with reference to FIG.

The second base station may receive a first message requesting measurement of the channel occupancy state from the first base station. The second base station may measure the channel occupation state based on the information included in the first message (S1210). The second base station can measure the channel occupation state in the same or similar manner as that of step S610 described with reference to Fig.

The second base station may transmit a second message including information indicating a channel occupation state to the first base station in response to the first message (S1220). The second message may be transmitted to the first base station based on an upper layer protocol or an X2 interface. The second message may be the same as the second message described with reference to FIG.

The first base station may receive the second message from the second base station. The first base station may change the contention window size based on the channel occupancy state included in the second message (S1230). The first base station may change the size of the contention window in the same or similar manner as that of step S630 described with reference to FIG.

In addition, the first base station can perform communication in the license-exempt band based on the size of the changed contention window. Here, the first base station can perform communication in the same or similar manner as step S640 described with reference to Fig. Also, the first base station may inform the UE of the size of the changed contention window. For example, the size of the modified contention window may be transmitted via the RRC message or DCI.

Next, a method of activating the license-exempted bandwidth channel based on the channel occupation state will be described. Here, the license-exempt band channel may be a license-exempt band cell.

13 is a flowchart showing a method of activating a license-exempted band channel based on a channel occupation state.

Referring to FIG. 13, a communication node (e.g., base station, UE) may form the wireless communication network described with reference to FIGS. 1-4 and may support license and license-exempt bands. The communication node may support carrier aggregation. The communication node may be configured the same or similar to the communication node 500 described with reference to FIG. The timing of the subframe (or slot, OFDM symbol, etc.) of the license band may be the same as the timing of the subframe (or slot, OFDM symbol, etc.) of the license-exempt band.

The communication node can measure the channel occupation state in a plurality of channels of the license-exempt band (S1300). For example, the communication node can measure the channel occupancy state in a plurality of channels of the license-exempt band based on the measurement method of the channel occupancy state described with reference to Fig. 6 or Fig.

The communication node may compare the channel occupation state of each of the plurality of channels with a preset threshold value. The communication node can select at least one channel having a channel occupation state equal to or less than a preset threshold value (S1310). The communication node may activate the selected license-exempt bandwidth channel (S1320). For example, if the communication node is a base station, the base station may request activation of the selected license-exempt bandwidth channel from the UE. When an activation request for a license-exempted bandwidth channel is received, the UE may activate the license-exempted bandwidth channel. Alternatively, if the communication node is a UE, the UE may directly activate the selected license-exempt band channel. The base station and the UE can perform communication in an unlicensed band channel that is active.

The methods according to the present invention can be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the computer readable medium may be those specially designed and constructed for the present invention or may be available to those skilled in the computer software.

Examples of computer readable media include hardware devices that are specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by the compiler 1, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate with at least one software module to perform the operations of the present invention, and vice versa.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

Claims (20)

A method of operating a user equipment (UE) in a communication network,
Measuring a received signal strength in a measurement interval within a license-exempted band;
Determining a channel occupied state by comparing the measured received signal strength with a preset threshold value; And
And reporting to the base station information indicating the channel occupancy state. The method according to claim 1,
Wherein the channel occupancy state is a ratio of an interval in which the measured received signal strength is greater than or equal to the preset threshold value to the measurement interval. The method according to claim 1,
Wherein the channel occupancy state is a ratio of the number of samples for which the measured received signal strength is greater than or equal to the predetermined threshold value to the total number of samples in the measurement interval. The method according to claim 1,
Wherein the information indicating the channel occupancy state is transmitted to the base station via a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH). The method according to claim 1,
The method comprising:
Further comprising receiving a message requesting measurement of a channel occupancy state from the base station. The method of claim 5,
Wherein the message comprises information relating to the periodicity of the measurement period of the received signal strength and the start of the measurement. The method of claim 6,
Wherein the message further comprises information related to a measured channel frequency, the predetermined threshold, and a duration of a duration. The method of claim 5,
Wherein the message is a radio resource control (RRC) message. A method of operating a base station in a communication network,
Generating a first message requesting measurement of a channel occupancy state;
Transmitting the first message to a UE; And
In response to the first message, a second message including information indicating a channel occupation state determined based on a result of comparison between a received signal strength measured in a measurement interval in the license-exempt band and a predetermined threshold, The method comprising the steps of: The method of claim 9,
Wherein the channel occupancy state is a ratio of an interval in which the measured received signal strength is greater than or equal to the preset threshold value to the measurement interval. The method of claim 9,
Wherein the channel occupancy state is a ratio of the number of samples in which the measured received signal strength is equal to or greater than the preset threshold value to the total number of samples in the measurement interval. The method of claim 9,
Wherein the first message comprises information related to a periodicity of a measurement period of a received signal strength and a measurement start time. The method of claim 12,
Wherein the first message further comprises information related to a measured channel frequency, the predetermined threshold, and a duration of a duration. The method of claim 9,
Wherein the first message is a radio resource control (RRC) message. The method of claim 9,
Wherein the second message is received from the UE via a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH). As a UE supporting a license-exempt band,
A processor; And
Wherein at least one instruction executed by the processor comprises a stored memory,
Measuring a received signal strength in a measurement interval within the license-exempt band;
Determining a channel occupied state by comparing the measured received signal strength with a predetermined threshold value; And
And to report to the base station information indicating the channel occupancy state. 18. The method of claim 16,
Wherein the channel occupancy state is a ratio of an interval in which the measured received signal strength is greater than or equal to the preset threshold value to the measurement interval. 18. The method of claim 16,
Wherein the channel occupancy state is a ratio of the number of samples in which the measured received signal strength is equal to or greater than the preset threshold value to the total number of samples in the measurement interval. 18. The method of claim 16,
Wherein the at least one instruction comprises:
Further comprising receiving a message requesting measurement of a channel occupancy state from the base station. The method of claim 19,
Wherein the message comprises information related to a measured channel frequency, the predetermined threshold, a duration of a duration, a periodicity of a measurement period of a received signal strength, and a measurement start time.

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