Patent Description:
Therefore, the <NUM> or pre-<NUM> communication system is also called a "Beyond <NUM> Network" or a "Post LTE System". In the <NUM> system, hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access(NOMA), and sparse code multiple access (SCMA) as an advanced access technology have also been developed.

The Internet, which is a human centered connectivity network where humans generate and consume information, is now evolving to the Internet of things (loT) where distributed entities, such as things, exchange and process information without human intervention. The Internet of everything (IoE), which is a combination of the loT technology and the big data processing technology through connection with a cloud server, has emerged.

Application of a cloud radio access network (RAN) as the above-described big data processing technology may also be considered an example of convergence of the <NUM> technology with the loT technology.

A wide bandwidth may be needed in order to satisfy user needs associated with high traffic. However, frequency bands are restricted, which is a problem. Accordingly, licensed assisted access is defined, which is a technology for using LTE in an unlicensed band. In this instance, there is a desire for a method for coexistence of an unlicensed band used by a Wi-Fi system and a band used by an LTE system.

<CIT> discloses a coordination mechanism which involves the reporting of WLAN activity times by the WLAN module to the LTE module and ensuring that the LTE-U module does not use LTE in case these activities would interfere with the activities of the WLAN module. <CIT> discloses a method for coordinating LTE with Wi-Fi access point. A WiFi access point is used as a coordinator for LAA-LTE access point transmissions (i.e., the WiFi access point is used to identify and select a channel for transmissions on behalf of the LAA-LTE access point).

An aspect of the disclosure is to provide a method and apparatus for decreasing contention between LAA and Wi-Fi for channel access, and for minimizing interference if a Wi-Fi radio access technology and an LAA-LTE radio access technology coexist within a single base station device (e.g., a small cell). A situation that does not allow a channel avoidance scheme frequently occurs in multi-LAA-LTE/Wi-Fi base station device environment. Various technologies to overcome the same are used, but they clearly have limits.

According to the method of the disclosure, contention for a channel between LAA-LTE and Wi-Fi may be eased and interference may be controlled, and thus, the performance of a network may be improved and the amount of power consumed by terminals connected to respective radio access technologies may be reduced.

Aspects or embodiments of the disclosure which do not fall under the scope of the claims are not included in the scope of invention.

In accordance with an aspect of the disclosure, a method of a first module of a base station in a wireless communication system, according to claim <NUM>, is provided.

In accordance with an aspect of the disclosure, a method of a second module of a base station in a wireless communication system, according to claim <NUM>, is provided.

In accordance with an aspect of the disclosure, a first module of a base station in a wireless communication system, according to claim <NUM>, is provided.

In accordance with an aspect of the disclosure, a second module of a base station in a wireless communication system, according to claim <NUM>, is provided.

According to the disclosure, contention occurring when LAA-LTE and Wi-Fi coexist may be alleviated, so the performance of a cell may be increased and the amount of power consumed by a terminal may be reduced.

According to the disclosure, an LAA-LTE access point (AP) module and a Wi-Fi AP module divide a service time and thus, contention may be eased and deterioration in performance caused by collision and interference may be dramatically reduced. In addition, a base station informs terminals of the time when to wake up and operate, so unnecessary activation latency of LAA-LTE terminals may be dramatically reduced and the amount of power consumed may be decreased.

A packet may be protected by a trigger frame, and thus, packet loss may be prevented. Further, if a channel environment is poor, a base station does not allocate a TWT service period (SP), and thus, use of an unlicensed band may be reduced and deterioration in the performance may be prevented.

Hereinafter, embodiments of the disclosure will be described in detail in conjunction with the accompanying drawings. In the following description of the disclosure, a detailed description of known functions or configurations incorporated herein will be omitted when it may make the subject matter of the disclosure unnecessarily unclear. The terms which will be described below are terms defined in consideration of the functions in the disclosure, and may be different according to users, intentions of the users, or customs. Therefore, the definitions of the terms should be made based on the contents throughout the specification.

As used herein, the "unit" refers to a software element or a hardware element, such as a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC), which performs a predetermined function. However, the "unit" does not always have a meaning limited to software or hardware. The "unit" may be constructed either to be stored in an addressable storage medium or to execute one or more processors. Therefore, the "unit" includes, for example, software elements, object-oriented software elements, class elements or task elements, processes, functions, properties, procedures, sub-routines, segments of a program code, drivers, firmware, micro-codes, circuits, data, database, data structures, tables, arrays, and parameters. The elements and functions provided by the "unit" may be either combined into a smaller number of elements, or a "unit", or divided into a larger number of elements, or a "unit". Moreover, the elements and "units" or may be implemented to reproduce one or more CPUs within a device or a security multimedia card.

In recent years, long-term evolution (LTE) has dramatically grown and succeeded. However, a wider bandwidth is still needed in order to satisfy user requirements associated with high traffic. Frequency capacity is limited and communication operators may have difficulty in providing a bandwidth capable of satisfying users, due to high costs of frequency. To overcome the same, licensed assisted access LTE (LAA-LTE), which is new technology for using LTE in an unlicensed band, has been defined.

An unlicensed band that LAA uses is <NUM>, and is a band which is frequently used in a wireless fidelity (Wi-Fi) system such as IEEE <NUM>. 11a/n/ac/ax or the like. Wi-Fi operates based on a carrier sense multiple access and collision avoidance (CSMA/CA) for coexistence in an unlicensed band. However, as LAA that uses an unlicensed band has been employed, various schemes for coexistence in an unlicensed band have been provided for an LAA system.

As representative schemes, <NUM>) channel avoidance scheme, <NUM>) duty cycle-based coexistence scheme, <NUM>) CTS-to-self and RTS/CTS scheme, and <NUM>) back-off-based listen before talk (LBT) scheme have been provided. Detailed descriptions thereof are as follows.

In this instance, the methods have problems as follows.

Therefore, the disclosure provides a method and apparatus for decreasing channel access contention between LAA and Wi-Fi and for minimizing interference if Wi-Fi radio access technology and LAA-LTE radio access technology coexist within a single base station device (e.g., a small cell).

<FIG> is a diagram illustrating the structure of a base station for a CTS/RTS-based LAA/WI-FI coexistence method.

Referring to <FIG>, a base station (or a small cell) <NUM> includes an LAA module <NUM>. The LAA module <NUM> includes an LAA transceiver <NUM> and a processing circuit. The processing circuit may include a processor and a memory (a channel selector <NUM> and a scheduler <NUM>).

As illustrated in <FIG>, the LAA module operates independently from a Wi-Fi module. Therefore, the LAA module may transmit a signal by only determining whether a Wi-Fi signal is present, or may perform a collision prevention transmission by utilizing RTS/CTS.

Conventionally, in the case of Wi-Fi that operates in an unlicensed band, if an access point (AP) has data to send, and sends a beacon signal, a terminal wakes up after a predetermined period of time and transmits or receives the data. In this instance, if multiple terminals access the AP, there may be multiple terminals which wake up at similar points in time, and this may cause packet collision, may cause the terminal to unnecessarily consume power, and the like. Therefore, a target wake time (TWT) technology has been employed, and thus, the AP informs a terminal of the time at which the terminal needs to wake up so as to overcome the above-mentioned problem.

Therefore, in order to alleviate a channel contention between LAA and Wi-Fi and to control interference, if a base station desires to use an unlicensed band, the disclosure provides a method in which an LAA module requests, from a Wi-Fi module, TWT service period (SP) resource allocation for LAA transmission, and the Wi-Fi module identifies the request and allocates a TWT SP so as to ease interference and contention.

To this end, according to the disclosure, the base station may include an LAA module, a Wi-Fi module, and a scheduler which is capable of controlling each of the LAA module and the Wi-Fi module. However, embodiments of the disclosure are not limited thereto, and may also be applicable to the case in which a base station includes only an LAA module. Detailed descriptions will be provided as below.

<FIG> is a diagram illustrating a TWT information element (IE).

Referring to <FIG>, the TWT information element may include fields, such as element ID <NUM>, length <NUM>, control <NUM>, request type <NUM>, target wake time <NUM>, nominal minimum TWT wake duration <NUM>, TWT wake interval mantissa <NUM>, broadcast TWT info <NUM>, and the like. Based on the information, the terminal may identify a wakeup time, a wakeup period, and the like, and may transmit or receive a signal during the corresponding time.

<FIG> is a diagram illustrating a trigger frame format.

Referring to <FIG>, a trigger frame may include fields, such as frame control <NUM>, duration <NUM>, RA <NUM>, TA <NUM>, common info <NUM>, user info <NUM>, padding <NUM>, FCS <NUM>, and the like.

A Wi-Fi AP module reserves use of a channel via a trigger frame, and specifies devices to use during the corresponding time. In addition, in the case of a Wi-Fi system, synchronization needs to be performed, which is a drawback. Therefore, even in the case in which a Wi-Fi AP allocates a TWT, devices that belong to a TWT service period are capable of joining transmission contention after the Wi-Fi AP transmits the trigger frame and performs synchronization.

<FIG> is a diagram illustrating the configuration of a base station according to an embodiment of the disclosure.

Referring to <FIG>, a base station (or a small cell device) may include an LAA-LTE module <NUM>, a Wi-Fi AP module <NUM>, and a controller <NUM> that is capable of controlling each of the LAA-LTE module <NUM> and the Wi-Fi AP module <NUM>. However, embodiments of the disclosure are not limited thereto, and may also be applicable to the case in which a base station includes only an LAA module.

In addition, although the disclosure provides descriptions using terms "LAA module" and "Wi-Fi module" for ease of description, "LAA module" and "Wi-Fi module" may be replaced with terms "first module" and "second module", respectively.

Further, each of the LAA module and the Wi-Fi module may include a controller (or scheduler) and a transceiver. As illustrated in <FIG>, an interface, in addition to a target processor, may be further included. The configurations of the LAA module and the Wi-Fi module are merely examples, and some components may be omitted or added, and each component may be controlled by the controller.

The LAA-LTE module may identify channel environment information and terminal information, and a current traffic status, so as to determine whether to use a licensed/unlicensed band. Based on the determination, the LAA-LTE module may share, with an LAA-LTE terminal, information associated with a frequency and a time at which data transmission is performed, and may perform data transmission or reception.

The Wi-Fi module according to the disclosure may support an AP mode and an STA mode according to a scenario used. Detailed descriptions thereof will be provided with reference to <FIG> and <FIG>.

<FIG> is a diagram illustrating an example in which a WI-Fi module operates in an AP mode according to an embodiment of the disclosure.

Referring to <FIG>, in the case in which a base station (or a small cell device) <NUM> provides a Wi-Fi data network service, a Wi-Fi module operates in an AP mode and provides a data network service to Wi-Fi terminals <NUM>, <NUM>, <NUM>, and <NUM>. The Wi-Fi module collects and controls information associated with Wi-Fi terminals that access the Wi-Fi module, and may use a TWT technology defined in <NUM>. 11ax or <NUM>. The Wi-Fi module identifies a request from a terminal and a channel state, and a current traffic status, so as to control a wake time for the terminal.

<FIG> is a diagram illustrating an example in which a Wi-Fi module operates in an STA mode according to an embodiment of the disclosure.

Referring to <FIG>, in the case in which a Wi-Fi module is used for the purpose of backhaul or monitoring, as opposed to the purpose of a data network service in a base station (a small cell device) <NUM>, the Wi-Fi module may operate in an STA mode. Therefore, the Wi-Fi module collects ambient Wi-Fi network information and provides optimal channel information to an LAA-LTE module.

In addition, the Wi-Fi module accesses or performs association with a neighboring Wi-Fi AP <NUM> that supports TWT, requests a TWT SP on behalf of the LAA-LTE module, so as to secure a service period.

As described above, if the LAA-LTE module desires to use an unlicensed band, the disclosure provides a method in which the LAA-LTE module requests, from the Wi-Fi module, TWT SP resource allocation for LAA-LTE transmission, and a Wi-Fi AP identifies the request and allocates a TWT SP so that interference and contention may be alleviated. In the disclosure, for ease of description, descriptions are provided using a term, "TWT SP resource", from the perspective that a base station configures a resource which is to be used by a terminal in an unlicensed band when the terminal wakes up. However, the scope of the disclosure is not limited thereto. That is, "TWT SP resource" may be replaced with a normal term, "unlicensed band resource", which means a resource period in an unlicensed band that the terminal is to use when waking up. That is, the operation in which the Wi-Fi module allocates a TWT SP may be replaced with an operation of setting a time at which the terminal is to use an unlicensed band.

Specifically, the LAA-LTE module requests use of a TWT SP from the Wi-Fi module. To this end, the LAA-LTE module may transmit a TWT SP request (update). The TWT SP request message may include information as below.

In this instance, all the information may not need to be included in the TWT SP request message, and at least one piece of the information may be included in the TWT SP request message. In addition, information other than the above-described information may be included in the message.

In response to the request, the Wi-Fi module may transfer a TWT SP response to the LAA module. The TWT SP response message may include information as below.

In this instance, all the information may not need to be included in the TWT SP response message, and at least one piece of the information may be included in the TWT SP response message. In addition, information other than the above-described information may be included in the message.

Further, if it is desired to terminate a TWT SP, a TWT SP termination message may be transmitted. The message may include a code that specifies the reason of the TWT SP termination.

In addition, information may be transmitted or received via a synchronization interface <NUM> (e.g., a trigger-enabled TWT SP synchronization interface). The interface may be a signaling interface which is connected between an LAA-LTE module and a Wi-Fi module in order to report the start of a TWT SP immediately after a trigger frame is transmitted. By transmitting or receiving information via the interface, the effect of the above-mentioned trigger frame transmission may be obtained. That is, an LAA is capable of starting operation accurately at the point in time at which a TWT resource is allocated. In addition, by transmitting or receiving information associated with the point in time at which the TWT resource ends via the interface, the point at which the LAA module ends operation may be accurately reported. If the LAA module and the Wi-Fi module use different clocks, a time error that could occur needs to be taken into consideration. That is, information needs to be transferred a single subframe transmission time ahead of the start and end of the TWT SP, the single subframe transmission time being a minimum operation time of an LAA device. Information transmitted via the LAA module and the interface may be as below.

Hereinafter, detailed operations of the disclosure will be described.

<FIG> is a diagram illustrating a process in which an LAA module receives allocation of a resource of an unlicensed band according to an embodiment of the disclosure.

Referring to <FIG>, a base station identifies whether use of a resource of an unlicensed band is requested (or is needed) in operation S510. For example, if a resource of a licensed band to be used is insufficient, the base station may determine that a resource of an unlicensed band needs to be used.

If the use of the unlicensed band is needed, an LAA module of the base station transmits a TWT SP request message that requests a resource of the unlicensed band to a Wi-Fi module in operation S520.

The Wi-Fi module of the base station may determine whether to allocate a resource of the unlicensed band (TWT SP for LAA-LTE) for LAA, based on the request information. If unlicensed band resource allocation fails or it is determined not to allocate a resource of the unlicensed band, the Wi-Fi module transmits a TWT SP response message so as to reject the request.

If a resource of the unlicensed band is allocable, the Wi-Fi module of the base station may allocate one of TWT IDs which are currently not allocated, and may determine an unlicensed band resource (LAA-LTE TWT SP). In addition, the Wi-Fi module transmits a TWT SP response message based on the determined information, and accepts the received request.

The LAA-LTE module identifies whether the request is accepted based on the received response message in operation S530. In addition, the LAA module identifies the allocated unlicensed band resource in operation S540, and determines whether to join TWT.

If the allocated unlicensed band resource (SP) in the response is insufficient, the LAA module may terminate unlicensed band resource allocation (TWT SP) in operation S596. If the unlicensed band resource allocation is terminated, the LAA-LTE module operates in a contention mode, as opposed to a TWT operation mode.

If the allocated unlicensed band resource (SP) is sufficient, the LAA module may schedule (scheduling) the resource for the LAA-LTE terminal based on the allocated unlicensed band resource (TWT SP) in operation S550, and may wait until a TWT SP start point arrives. In addition, the Wi-Fi module may inform another Wi-Fi terminal of a service period for LAA-LTE via a beacon signal.

If a TWT SP starts in operation S560, the LAA-LTE module wakes up and prepares a transmission or reception operation in operation S570, and identifies whether a synchronization interface (TWT SP synchronization interface) is in an SIG_UP state in operation S580.

If the synchronization interface is in the SIG_UP state, the LAA module starts signal transmission or reception in operation S590. After signal transmission or reception ends, the LAA module identifies whether signal transmission is continuously needed in operation S595. If signal transmission is continuously needed, the LAA module waits for a subsequent TWT SP, and schedules a resource for the LAA terminal in operation S550. If unlicensed band transmission is not needed, the LAA module terminates unlicensed band resource allocation (TWT SP) in operation S596.

The drawing may include only some components by omitting some components within the scope that does not change the subject matter of the disclosure.

<FIG> is a diagram illustrating a process of allocating a resource of an unlicensed band if a Wi-Fi module is in an AP mode according to an embodiment of the disclosure.

Referring to <FIG>, a Wi-Fi module receives a TWT SP request message from an LAA module in operation S610.

The Wi-Fi module of a base station determines whether an unlicensed band resource (TWT SP for LAA) is allocable based on the request information in operation S620.

If the TWT SP is not allocable, the Wi-Fi module transmits a TWT SP response message so as to reject the request in operation S630.

If the unlicensed band resource is allocable, the Wi-Fi module of the base station may allocate one of TWT IDs which are currently not allocated in operation S640, and may schedule the unlicensed band resource (LAA TWT SP) in operation S650. In addition, the Wi-Fi module transmits a TWT SP response message based on the determined information so as to accept the received request in operation S660.

The Wi-Fi module determines whether a TWT SP termination message is received in operation S670. If the SP that is allocated to the LAA module is insufficient or unlicensed band transmission is not needed, the Wi-Fi module may receive the TWT SP termination message. If the TWT SP termination message is received, the Wi-Fi module cancels unlicensed band resource allocation (LAA TWT SP) in operation S680.

<FIG> is a diagram illustrating an example in which a Wi-Fi TWT SP and an LAA-LTE TWT SP coexist if a Wi-Fi module operates in an AP mode according to an embodiment of the disclosure.

A Wi-Fi AP transmits a beacon frame periodically, and transmits TWT IEs. In this instance, a TWT IE operates according to IEEE <NUM> standard. During an unlicensed band resource period (Wi-Fi TWT SP) <NUM> allocated for Wi-Fi, Wi-Fi devices belonging to a TW ID may operate according to the TW ID specified in a TWT IE. During an unlicensed band resource period (LAA TWT SP) <NUM> allocated for LAA-LTE, only LAA-LTE devices may operate. All devices belonging to TWT may need to operate only in their service periods (SP). In order to prevent interference from a device that does not belong to TWT or legacy Wi-Fi devices during the LAA-LTE TWT SP, a base station sets a NAV as long as the length of the SP, and transmits a trigger frame.

Immediately after the trigger frame is transmitted, a TWT SP synchronization interface enters the SIG_UP states, and LAA-LTE transmission or reception starts. The detailed method of LAA-LTE transmission is omitted.

If the trigger frame does not cover enough the LAA-LTE TWT SP, the base station divides the triggering frame and transmits the same several times. During the trigger frame transmission time, the TWT SP synchronization interface needs to maintain an SIG_DOWN state. After the LAA-LTE TWT SP ends, LAA-LTE terminals return to an idle state.

Hereinafter, a TWT SP allocation method for LAA will be described.

A Wi-Fi module continuously measures channel utilization (CU, %) which is currently used. The Wi-Fi module estimates a currently available channel duration (TCU) based on a beacon interval and the CU. The Wi-Fi module estimates the maximum allocable channel duration (Tres), excluding the currently allocated TWT SP.

In addition, the Wi-Fi module determines whether to accept the allocation request from the LAA module, based on a requested channel duration and the maximum allocable channel duration. For example, if <MAT> (a remaining service period per second) is greater than <MAT> (a requested service period per second), the Wi-Fi module accepts the requested TWT SP allocation, and allocates a resource in response to the request. If the remaining capacity is insufficient, the Wi-Fi module allocates a TWT SPS as much as the remaining time. If a time to be allocated does not remain, the Wi-Fi may reject the TWT SP allocation request. If the noise floor of the channel that is being measured is significantly high, the Wi-Fi module also rejects the TWT SP allocation request. If the request is rejected, or the allocated remaining time is insufficient, the LAA-LTE module terminates the TWT SP, and operates in a contention mode, as opposed to operating in a TWT operation mode.

Hereinafter, operation when the Wi-Fi module operates in an STA mode will be described.

Even in the case in which the Wi-Fi module operates in the STA mode, the LAA module of <FIG> may perform the same operation.

<FIG> is a diagram illustrating a process of allocating a resource of an unlicensed band if a Wi-Fi module is in an STA mode according to an embodiment of the disclosure.

If an LAA-LTE module needs to use an unlicensed band, the LAA-LTE module requests a TWT SP from the Wi-Fi module. Therefore, the Wi-Fi module may receive a TWT SP request message from the LAA module in operation S810.

The Wi-Fi module performs TWT negotiation with an AP to which the Wi-Fi module is connected, in response to the request in operation S820. If the TWT negotiation is already done, this operation may be omitted. The TWT negotiation may be performed according to a TWT operation defined in <NUM>. 11ax standard.

The Wi-Fi module determines whether the TWT negotiation is successfully performed in operation S830. TWT negotiation is the process in which a Wi-Fi terminal and an AP identify whether TWT is supported therebetween and identify whether joining TWT is agreed. If the connected Wi-Fi AP does not support a TWT function, the Wi-Fi AP transmits a TWT SP response message so as to reject the request.

If the TWT negotiation is successfully performed, the Wi-Fi module transmits a TWT SP request to the AP in operation S850. The Wi-Fi module transmits a TWT request frame to the connected AP in order to perform request, and waits for a TWT SP.

The Wi-Fi module may determine whether requesting the TWT SP is successfully performed in operation S860. If the Wi-Fi module receives a TWT SP response message (reject message) that rejects a TWT SP from the Wi-Fi AP in response to the TWT SP request, the Wi-Fi module transmits a TWT SP response message to the LAA-LTE module so as to reject the TWT SP request. If an allocated SP in the response received from the Wi-Fi AP is insufficient, the Wi-Fi module may terminate the TWT SP.

Therefore, the LAA module operates in a contention mode, as opposed to operating in a TWT operation mode.

If requesting the TWT SP is successfully performed, the Wi-Fi module may receive a response message that accepts the TWT SP request in operation S870.

Therefore, the Wi-Fi module may identify a TWT IE that the connected Wi-Fi AP transmits, may schedule an LAA-LTE terminal, and may wait until a TWT SP start point arrives in operation S880 and S885.

If the Wi-Fi module receives a trigger frame from the AP, the Wi-Fi module determines that the TWT SP starts, and switches a TWT SP synchronization interface to an SIG_UP state.

The LAA-LTE module starts transmission or reception after checking whether the TWT SP synchronization interface is in the SIG_UP state while preparing data transmission. After transmission or reception ends, the LAA module waits for a subsequent TWT SP if transmission is continuously needed. The LAA module terminates the TWT SP if unlicensed band transmission is not needed.

Therefore, the Wi-Fi module receives a TWT SP termination message in operation S890. The Wi-Fi module cancels the TWT SP for the LAA module in operation S895.

<FIG> is a diagram illustrating an example in which a TWT SP and an LAA-LTE TWT SP coexist if a Wi-Fi module operates in an STA mode according to an embodiment of the disclosure.

A Wi-Fi module operating in an STA mode receives a TWT IE of a beacon frame that is periodically transmitted from a connected Wi-Fi AP. The Wi-Fi module identifies the TWT IE, and if a TWT SP allocated to the Wi-Fi module is present, the Wi-Fi module wakes up in order to receive a trigger frame at the corresponding time. If the trigger frame is received, a TWT SP synchronization interface is switched to an SIG_UP state <NUM> and LAA-LTE transmission or reception starts.

If the trigger frame does not cover enough an LAA-LTE TWT SP, the trigger frame is divided and transmitted several times. During the trigger frame transmission time, the TWT SP synchronization interface needs to maintain a SIG_DOWN state <NUM>. After the LAA-LTE TWT SP ends, LAA-LTE terminals return to an idle state.

Hereinafter, a channel selection method for LAA will be described. In order to select an optimal channel for LAA-LTE transmission, the Wi-Fi module may select a channel using neighboring LAA-LTE base station information and ambient Wi-Fi information.

The Wi-Fi module may select an optimal channel using the strength of a received signal. In this instance, the signal strength may include at least one of a reference signal received power (RSRP) or a received signal strength indication (RSSI). In addition, noise may be taken into consideration in order to select an optimal channel. Specifically, for example, the Wi-Fi module may estimate load metric shown below in order to select an optimal channel. <MAT> <MAT> <MAT>.

A reference signal received power (RSRP) (dBm) is the signal strength of a neighboring base station measured by an LAA-LTE device. A received signal strength indication (RSSI) (dBm) is the signal strength of a neighboring Wi-Fi AP measured by a Wi-Fi device. A noise floor (NF) is an ambient ambiguous noise measured by the Wi-Fi device. Based on the result of the calculation, the Wi-Fi device may select a channel that has the lowest load, and may transfer information associated with the selected channel to the LAA-LTE device via a TWT SP response message.

When allocating an unlicensed band resource (TWT negotiation), a Wi-Fi TWT SP duration and a TWT SP interval may be changed depending on the amount of resources that LAA needs. In order to determine the same, the LAA-LTE module estimates throughput (Ruband, bps) required in an unlicensed band. Ruband may be estimated based on the difference between a packet rate (bps) received in the current queue and throughput (Rband, bps) provided in the current licensed band. The Wi-Fi TWT SP duration and the TWT SP interval needed may be determined based on the estimated Ruband and the data rate of LTE.

In the drawings in which methods of the disclosure are described, the order of the description does not always correspond to the order in which steps of each method are performed, and the order relationship between the steps may be changed or the steps may be performed in parallel.

Alternatively, in the drawings in which methods of the disclosure are described, some elements may be omitted and only some elements may be included therein without departing from the essential scope of the disclosure.

Further, in methods of the disclosure, some or all of the contents of each embodiment may be combined without departing from the essential scope of the disclosure.

Claim 1:
A method performed by a first module (<NUM>) of a base station in a communication system, the method comprising:
transmitting, to a second module (<NUM>) of the base station, a resource allocation request message associated with an unlicensed band, wherein the resource allocation request message includes information on at least one of minimum target wake time, TWT, service period, SP, duration, a required TWT SP interval, a candidate channel list or a required bandwidth;
receiving, from the second module, as a response to the request message, a response message including information on a TWT for a terminal;
allocating a resource of the unlicensed band to the terminal based on the TWT;
characterized by
identifying a transmission start time of the TWT SP, based on an interface state between the first module and the second module; and
transmitting, to the terminal, data on the allocated resource based on the transmission start time of the TWT SP.