KR101790198B1 - Method and apparatus for supporting license-assisted access in a wireless communication system - Google Patents

Method and apparatus for supporting license-assisted access in a wireless communication system Download PDF

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KR101790198B1
KR101790198B1 KR1020160023276A KR20160023276A KR101790198B1 KR 101790198 B1 KR101790198 B1 KR 101790198B1 KR 1020160023276 A KR1020160023276 A KR 1020160023276A KR 20160023276 A KR20160023276 A KR 20160023276A KR 101790198 B1 KR101790198 B1 KR 101790198B1
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license
terminal
band
band terminal
support connection
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KR20170100867A (en
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강병준
박세웅
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서울대학교산학협력단
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access, e.g. scheduled or random access
    • H04W74/08—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access]
    • H04W74/0808—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access] using carrier sensing, e.g. as in CSMA
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/02—Arrangements for optimising operational condition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/08—Access point devices

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly, to a method and a base station for a base station supporting a license support connection. According to an aspect of the present invention, there is provided a method for controlling a license-based access terminal, the method comprising: selecting a licensed band terminal to perform a license support connection based on a delay time to be experienced by a license- And a contention window to be applied to the selected license band terminal by applying a proportional fair algorithm based on the yields of the non-licensed band terminal and the selected license band terminal in communication within the coverage of the base station, A method for supporting a License-Assisted Access (LAA) in a base station in a wireless communication system, the base station comprising:

Description

Technical Field [0001] The present invention relates to a method and apparatus for supporting a license support connection in a wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication, and more particularly, to a method and a base station for a base station supporting a license support connection.

Recently, LTE-LAA (LTE-License-Assisted Access) techniques have been researched to solve the shortage of frequency resources of LTE in the license-free frequency band and carrier aggregation (CA). Coexistence with WiFi may be a problem if LTE is used in the license-free frequency band. To solve this problem, there are a Listen Before Talk (LBT) based method and a duty cycle based method. In addition, the LBT-based scheme has a frame-based equipment (FBE) scheme similar to LTE and a load-based equipment (LBE) scheme similar to WiFi.

The LBE method is similar to the WiFi channel access method. When there is data to be transmitted to the terminal, the LBE method first senses the channel, transmits the signal when the channel is empty, and performs random back-off when the channel is in use. However, unlike WiFi, which increases the contention window size in the event of a collision, the LBE LBT maintains the contention window size due to the HARQ characteristics of the LTE. Accordingly, when the LTE mobile station uses the license-free frequency band, the mobile station can have a contention window size smaller than the contention window size of the WiFi mobile station, thereby increasing the occupancy probability of the license-exempt frequency band, have.

Korean Patent Publication No. 1020140050744 (Apr. 29, 2014) Korean Patent Publication No. 1020140125408 (Apr. 28, 2014)

A method and apparatus for determining a size of a contention window of a license-based terminal in consideration of the performance of a WiFi terminal in a wireless communication system supporting a license support connection.

According to an aspect of the present invention, a method for supporting a License-Assisted Access (LAA) in a base station in a wireless communication system includes determining a delay time to be experienced when a license- of service based on a proportional fair algorithm based on the yield of each of the non-licensed band terminals and the selected license band terminals being communicated within the coverage of the base station, And determining a size of a contention window to be applied to the selected license band terminal.

According to another aspect, a base station supporting a license support connection in a wireless communication system may include a processor coupled to the transceiver and the transceiver to communicate with the licensed band terminal, and the processor may be configured such that the licensed band terminal experiences a license- Selecting a licensed band terminal to perform a license support connection based on a delay time and a time delay QoS (Quality of Service) of the licensed band terminal, selecting a license band terminal to which the license support connection is to be performed, A proportional fair algorithm may be applied to determine the size of the contention window to be applied to the selected license band terminal.

According to another aspect, a method for a terminal to perform a license support connection in a wireless communication system includes receiving information on whether a license support connection is permitted from a base station and a size of a contention window to be applied when the license support connection is established, Sensing the carrier in the non-licensed band, and, if the carrier is sensed in the non-licensed band, performing a random back-off within the contention window size and again sensing, The size of the contention window is determined based on the delay time experienced by the licensee terminal in performing the license support connection and the license-bandwidth terminal selected based on the time-delay Quality of Service (QoS) of the licensee terminal and the non-license- Can be determined by applying a proportional fair algorithm based on the respective yields.

Specifically, the step of selecting a licensed band terminal to perform a license support connection comprises estimating the number of non-licensed band terminals in communication within the coverage of the base station, estimating the number of non-licensed band terminals, Calculating a minimum delay time that a license band terminal will experience when performing a license support connection based on a minimum contention window size among a range of a predetermined contention window size, And selecting a terminal that is larger than the delay.

The step of estimating the number of non-license-band terminals may use an RF fingerprinting method.

The step of determining the size of the contention window includes determining a size of a contention window to maximize the sum of the logarithms of the yields of the non-licensed band terminals and the selected license band terminals in communication within the coverage of the base station, The size of the window can be determined.

Further, a method for a base station supporting a licensed support connection in a wireless communication system further comprises determining whether to grant a licensed support connection to a licensed band terminal selected based on a degraded rate of a non-licensed band terminal resulting from a license support connection .

Wherein determining whether to grant a license support connection comprises calculating a first yield of the non-licensed band terminal if only the non-licensed band terminal performs non-licensed band communication, And calculating a second yield of the non-licensed band terminal when the selected licensed band terminal performs non-licensed band communication and calculating a second yield of the selected license band only when the rate of decrease of the second yield relative to the first yield is within a predetermined range And determining that the terminal is to perform a license support connection.

The license band terminal may be an LTE (Long Term Evolution) terminal, and the non-license band terminal may be a Wi-Fi terminal.

According to an embodiment of the present invention, the size of a contention window of a license-based terminal is determined in consideration of the performance of a WiFi terminal, thereby adjusting the size of a contention window of a license- Can be obtained.

1 is a diagram illustrating a wireless communication system supporting a license support connection to which an embodiment of the present invention may be applied.
FIG. 2 is a flowchart illustrating a method of determining a contention window size according to an exemplary embodiment of the present invention. Referring to FIG.
3 is a Markov chain model for explaining a method of calculating a time delay of a terminal performing a license support connection according to an embodiment of the present invention.
4 is a flowchart illustrating a method of determining a contention window size according to another embodiment of the present invention.
5 is a flowchart illustrating a method for a terminal to perform a license support connection according to an exemplary embodiment of the present invention.
6 is a configuration diagram of a base station according to an embodiment of the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, those skilled in the art will recognize that the present invention may be practiced without these specific details. For example, the following detailed description assumes that the mobile communication system is an IEEE (Institute of Electrical and Electronics Engineers) 802.11 and 802.19 system, or a 3GPP (3rd Generation Partnership Project) The present invention is applicable to any other mobile communication system except for the specific matters.

1 is a diagram illustrating a wireless communication system supporting a license support connection to which an embodiment of the present invention may be applied.

1, a wireless communication system 100 according to an exemplary embodiment includes a macro cell capable of performing communication with the macro base station 110 and a small cell capable of performing communication with the small cell base station 130 And may be configured as a two-tier network. At this time, the terminals 111 and 113 in the macro cell can receive services through the macro base station 110 and the license band. On the other hand, the terminals 131 and 133 in the small cell can receive service through one or more of the licensed band and the non-licensed band. Hereinafter, the small cell base station 130 may be referred to as a base station 130, and the terminals 131 and 133 in a small cell may be referred to as license band terminals 131 and 133. For example, the license band communication may be an LTE communication, and the terminals 111 and 113 in the macro cell and the terminals 131 and 133 in the small cell may be LTE terminals. Also, the non-licensed band service provided to the terminals 131, 133 in the small cell may be a License-Assisted Access (LAA) service for using the licensed band terminal in the license-free frequency band.

The wireless communication system 100 according to another example includes a WiFi AP 150 and WiFi terminals 151 and 153 that are included in or adjacent to a small cell providing non-licensed band services and perform non- ) May exist. Hereinafter, the WiFi terminals 151 and 153 may be referred to as non-license band terminals 151 and 153, respectively. When the small cell base station 130 and the terminals 131 and 133 in the small cell communicate through the non-licensed band, the WiFi AP 150 and the WiFi terminal 151 performing non- , 153 may occur.

FIG. 2 is a flowchart illustrating a method of determining a contention window size according to an exemplary embodiment of the present invention. Referring to FIG.

1 and 2, a base station 130 supporting a License-Assisted Access (LAA) firstly transmits a license-assisted access (LAA) A license band terminal to which a license support connection is to be performed may be selected based on the time delay QoS (Quality of Service) of the band terminal (S210). For example, the license-band terminals 131 and 133 may be LTE (Long Term Evolution) terminals, and the non-license-band terminals 151 and 153 may be Wi-Fi terminals.

At this time, the base station 130 may estimate the number of non-licensed band terminals 151 and 153 that are communicating within the coverage of the base station 130 in order to select the license band terminal to perform the license support connection. In one example, the base station 130 may estimate the number of non-licensed band terminals 151, 153 communicating within the coverage of the base station 130 using the RF fingerprinting scheme.

Then, the base station 130 determines whether or not the license band terminal 131 and the license band terminal 131 are the same based on the number of the estimated non-licensed band terminals 151 and 153, the number of the license band terminals 131 and 133, You can calculate the minimum latency that this license-supported connection will experience. For example, the predetermined contention window size range may be 4 to 32, and the minimum contention window size may be 4. The base station 130 can know the number of the license band terminals 131 and 133 and the time delay QoS information that are performing communication within its coverage. Based on the information, the base station 130 may calculate the minimum time delay experienced by the license band terminals 131 and 133 to perform the license support connection as shown in Equation (1) below.

Figure 112016019123793-pat00001

Here, subscript 1 means parameters for the license-band terminals 131 and 133, and subscript w means parameters for the non-license-band terminals 151 and 153. In this equation, L is the maximum number of retransmission limit, P c is the collision probability, T s is the average transmission time of all licensed band terminals and non-licensed band terminals when transmission is successful, T c is the average transmission time of all licensed band terminals and non- , Q is the size of the contention window, Slot is the size of the extended CCA (Extended Clear Channel Assessment) slot, Pf is the back channel of the channel, This means the probability of freezing the counter. At this time, P c , T s , T c and P f can be obtained by using two Markov chain models.

3 is a Markov chain model for explaining a method of calculating a time delay of a terminal performing a license support connection according to an embodiment of the present invention.

Equation 2 can be obtained by formally analyzing the Markov chain model of FIG.

Figure 112016019123793-pat00002

here,

Figure 112016019123793-pat00003
Is the channel occupancy probability of the non-licensed band terminal,
Figure 112016019123793-pat00004
P c, w represents the collision probability of the non-license band terminals 151 and 153, and P c, l represents the collision probability of the license band terminal 133 that performs the license support connection . At this time, each parameter value can be obtained by iterating Equation (2).

T s can be calculated as shown in Equation 3 below using the result calculated in Equation (2).

Figure 112016019123793-pat00005

Where N W is the number of non-licensed band terminals and N L is the number of licensed band terminals performing the license support connection.

T c can be obtained as shown in Equation (4) below.

Figure 112016019123793-pat00006

here,

Figure 112016019123793-pat00007
The collision probability between the license band terminals,
Figure 112016019123793-pat00008
The probability of collision between the licensed band terminal and the non-licensed band terminal,
Figure 112016019123793-pat00009
Represents the probability of collision between non-license-band terminals. Also, T c, l and T s, l represent the collision time and transmission time of the license band terminal,
Figure 112016019123793-pat00010
Can be defined as follows. Also, T c, w and T s, w denote the transmission time and the collision time of the non-licensed band terminal,
Figure 112016019123793-pat00011
Can be defined as follows. P f, l
Figure 112016019123793-pat00012
Can be defined as follows.

The base station 130 may choose to perform the license support connection for the terminals of the license band terminals 131 and 133 whose time delay QoS is greater than the minimum time delay calculated above. That is, it is possible to select a license band terminal satisfying the following equation (5).

Figure 112016019123793-pat00013

For example, if the time-delayed QoS of the licensed band terminal 131 is 3 ms, the time-delayed QoS of the licensed band terminal 133 is 5 ms, and the minimum time delay is 4 ms, then the base station 130 transmits a license- The license band terminal 133 can be selected as the terminal.

The base station 130 then applies a proportional fair algorithm based on the yield of each of the non-licensed band terminals 151 and 153 and the selected licensed band terminal 133 communicating within the coverage, The size of the contention window to be applied to the contention window 133 can be determined.

The extended clear channel assessment (CCA) at which the back-off is performed, that is, the extended clear channel assessment, when the license-enabled terminal 133 performs the license support connection and performs the non- ) * It can be the size of an extended clear channel assessment (CCA) slot. In addition, the time when the license band terminal 133 occupies the non-license band may be 13/32 * q (ms). Accordingly, changing the contention window size q may change the channel access probability and the channel usage time of the license-band terminal 133. [ This may affect the channel access probability and yield of the non-licensed band terminal. For example, increasing the contention window size (q) reduces the channel access probability but increases the time occupied by occupying the channel once. Therefore, the size of the contending window should be determined in consideration of the fairness and the yield, and the optimization problem must be solved as shown in Equation (6) below.

Figure 112016019123793-pat00014

Where N W is the number of non-licensed band terminals, N L is the number of licensed band terminals performing the license support connection, S W is the ratio of the time used by non-licensed band terminals to send payload, S L is a percentage of time that is used is licensed band terminal of the time to send a payload, W R is a non-licensed band, the terminal transmission rate, R L represents a licensed band terminal rate.

In one example, to determine the size of the contention window, the sum of the logarithm of the yield of each of the non-licensed band terminals 151 and 153 and the selected license band terminal 131 communicating within the coverage of the base station 130 is maximized The size of the contention window to be applied to the selected license band terminal 131 can be determined. In other words,

Figure 112016019123793-pat00015
Lt; / RTI >

S W and S L can be expressed by Equation (7) below.

Figure 112016019123793-pat00016

Here, subscript 1 means parameters for the license-band terminals 131 and 133, and subscript w means parameters for the non-license-band terminals 151 and 153. The above equation is the collision probability P c, T s is sent when any successful band licensed terminal and non-licensed band, the average transmission time of the terminal, T c are all licensed band terminal and non-conflicting times the average of the license-band terminal,

Figure 112016019123793-pat00017
The payload length is the remaining payload transmission time excluding the header and the padding bits during the channel occupation time,
Figure 112016019123793-pat00018
Is the channel occupancy probability of the non-licensed band terminal,
Figure 112016019123793-pat00019
Denotes the probability of channel occupancy of the license band terminal, and P t denotes the probability that at least one of the license band terminal and the non-license band terminal transmits. For example,
Figure 112016019123793-pat00020
9us,
Figure 112016019123793-pat00021
,
Figure 112016019123793-pat00022
Lt; / RTI > At this time,
Figure 112016019123793-pat00023
,
Figure 112016019123793-pat00024
, Pc, w , Pc, l can be obtained by iterating the above Equation (2). Also, P t
Figure 112016019123793-pat00025
As shown in Fig. Subsequently, the obtained S W and S L are substituted into Equation (6), and the sum of the logarithm of the yields of the non-licensed band terminals 151 and 153 and the selected license band terminals 131 being communicated within the coverage of the base station 130 The size of the competition window that maximizes the size of the competition window. The size of the contention window calculated as described above can be determined as the size of the contention window to be applied to the license band terminal 131.

4 is a flowchart illustrating a method of determining a contention window size according to another embodiment of the present invention.

Referring to FIG. 1 and FIG. 4, the base station 130 may calculate the minimum delay time that the license band terminal 131, 133 existing in its coverage performs when performing a license support connection (S410). To this end, the base station 130 must know the number of non-licensed band terminals 151, 153 existing within its coverage and the number of license band terminals 131, 133. At this time, the number of the non-license band terminals 151 and 153 can be estimated using the RF fingerprint method. Then, the base station 130 determines whether or not the license band terminal 131 and the license band terminal 131 are the same based on the number of the estimated non-licensed band terminals 151 and 153, the number of the license band terminals 131 and 133, You can calculate the minimum latency that this license-supported connection will experience. The minimum delay time can be obtained from Equation 1 and FIG. 3 described above with reference to FIG. 2, and duplicate description of the above description will be omitted.

Subsequently, the base station 130 may select to perform the license support connection among the license band terminals 131 and 133, in which the time delay QoS is larger than the calculated minimum time delay (S420). At this time, if there is no terminal in the license band terminals 131 and 133 whose time delay QoS is larger than the minimum time delay calculated above, the base station 130 does not perform the license support connection and returns to the initial state. On the other hand, if at least one of the license-band terminals 131 and 133 has a time delay QoS greater than the calculated minimum time delay, the terminal can be selected as a license-supported access terminal. For example, if the time-delayed QoS of the licensed band terminal 131 is 3 ms, the time-delayed QoS of the licensed band terminal 133 is 5 ms, and the minimum time delay is 4 ms, then the base station 130 transmits a license- The license band terminal 133 can be selected as the terminal.

Then, the base station 130 determines whether to allow the license support connection based on the selected license band terminal 133 (S430).

According to one embodiment, the base station 130 may determine whether to grant a license support connection to the selected license band terminal based on the degradation rate of the non-licensed band terminal due to the license support connection. To this end, the base station 130 may calculate the first yield of the non-licensed band terminals 151, 153 when only the non-licensed band terminals 151, 153 perform non-licensed band communication. That is, it is possible to calculate the first yield of the non-license band terminals 151 and 153, assuming that the license band terminal does not perform the license support connection.

The first yield rate of the non-license-terminal terminals 151 and 153 can be calculated by Equation (8) below.

Figure 112016019123793-pat00026

Here, subscript w means a parameter for the non-license-bandwidth terminals 151 and 153. The above equation is the collision probability P c, T s is sent when any successful band licensed terminal and non-licensed band, the average transmission time of the terminal, T c are all licensed band terminal and non-conflicting times the average of the license-band terminal,

Figure 112016019123793-pat00027
The payload length is the remaining payload transmission time excluding the header and the padding bits during the channel occupation time,
Figure 112016019123793-pat00028
Is the channel occupancy probability of the non-licensed band terminal, and P t is the probability that all the licensed band terminals and non-licensed band terminals transmit.

At this time, S W in Equation (8) can be obtained by using Equation (2) obtained through the Markov chain model as described with reference to FIGS. 2 and 3. However, in order to obtain the yield of only non-licensed band terminals

Figure 112016019123793-pat00029
= 0 can be calculated. At this time, the calculated S W becomes the first yield rate of the non-license band terminals 151 and 153.

The base station 130 may then calculate the second yield of the non-licensed band terminal if the non-licensed band terminal 151, 153 and the selected licensed band terminal 133 perform non-licensed band communication. For this, the base station 130 may calculate the yield, as calculated by Equation (5) above. However, at this time, in order to obtain the yield of only the non-licensed band terminal

Figure 112016019123793-pat00030
= 0, in order to reflect the influence of the selected license band terminal 133, the above equation (2) is used as it is. The thus calculated S W is the second yield of the non-license band terminals 151 and 153.

Thereafter, the base station 130 may determine that the license band terminal 133 selected only when the rate of decrease of the second yield relative to the first yield falls within a predetermined range, to perform the license support connection. As an example, if the second yield relative to the first yield

Figure 112016019123793-pat00031
Of the total number of licensed users. That is, the second yield / first yield>
Figure 112016019123793-pat00032
, Access to license support is allowed. E.g,
Figure 112016019123793-pat00033
Is 0.7, and the first yield = 100 and the second yield = 60, the second yield / first yield = 0.6, license support connection is not allowed. In this case, the base station 130 returns to the initial state again. On the other hand, if the first yield = 100 and the second yield = 80, the second yield / first yield = 0.8, license support connection is allowed.

If a license support connection is allowed, the base station 130 determines the size of the contention window to apply to the selected license band terminal 133 (S440). At this time, the size of the contention window can be expressed by Equation (6) as described above with reference to FIG. 2, and redundant contents are omitted.

5 is a flowchart illustrating a method for a terminal to perform a license support connection according to an exemplary embodiment of the present invention.

Referring to FIGs. 1 and 5, a terminal that is allowed to access a license support can receive information on whether a license support connection is permitted from a base station and a size of a competition window to be applied when accessing a license support. As an example, it can be assumed that a license support connection is allowed to the license band terminal 133.

License band terminal 133 may sense the carrier in the non-licensed band to make a license support connection (S610). For example, the time when the license band terminal 133 senses the channel may be 20 us or more.

Thereafter, the license band terminal 133 can determine whether the corresponding channel is in use through the sensing result (S620). When the carrier is sensed in the non-licensed band as a result of sensing the channel, the license band terminal 133 may perform a random back-off within the contention window size received from the base station 130 (S640). At this time, the contention window size is determined based on the delay time experienced by the licensee terminal in performing the license support connection and the non-license band in communication with the license band terminal selected based on the time-delayed Quality of Service (QoS) And may be determined by applying a proportional fair algorithm based on the yield of each terminal.

For example, when the size q of the contention window is 30, the license-band terminal 133 may select any number from 0 to 29 (for example, rand (0, q-1) The size of the contention window is multiplied by the size of the extended clear channel assessment (CCA) slot (S640). Thereafter, the license band terminal 133 may again sense the channel (S610).

On the other hand, when the channel is available, the license band terminal 133 can occupy the channel and perform communication. As an example, the license band terminal 133 may occupy the channel for 13/32 * q (ms).

6 is a configuration diagram of a base station according to an embodiment of the present invention.

Referring to FIG. 6, the base station 600 may include a transceiver 610 for performing communication with a license-band terminal, a processor 630 connected to the transceiver, and a memory 650. In one example, the processor 630 may select a licensed band terminal to perform a license support connection based on the delay time experienced by the licensed band terminal in performing the license support connection and the time delay Quality of Service (QoS) of the licensed band terminal have. Also, within the coverage of the base station 600, a proportional fair algorithm is applied based on the yield of each of the non-licensed band terminal and the selected license band terminal being communicated, and a contention window Can be determined.

The various embodiments and features described herein may be implemented in software, hardware, or a combination thereof. For example, a computer program executing a method and apparatus for performing embodiments of the present invention (executed by a processor, controller, CPU, etc., mobile terminal and / or network device of a computer) And may include at least one program code section or module. Likewise, a software tool that performs methods and apparatus for performing embodiments of the present disclosure (executed by a processor, controller, CPU, etc., mobile terminal and / or network device of a computer) And may include at least one program code section or module for performing the functions described herein.

Methods and apparatus for performing the embodiments of the present disclosure are compatible with various types of techniques and standards. The embodiments described herein relate to standards such as 3GPP (Global System for Mobile Communications (GSM), Wideband Code Division Multiple Access (WCDMA), UMTS, LTE, LTE-Advanced, etc.), IEEE 802, However, the above exemplary standards do not limit other related standards and techniques applicable to the various embodiments and features described herein.

The embodiments and features described herein may be implemented in various types of user devices (e.g., mobile terminals, handsets, wireless communication devices, etc.) and / or network devices, entities, components that support MTC and / .

The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The detailed description above should not be construed as limiting unless expressly specified otherwise, and should be interpreted broadly within the scope of the claims. Accordingly, it is intended that all changes and modifications within the equivalent scope of the invention be included within the scope of the present invention and interpreted within the scope of the claims.

The embodiments described above are those in which the elements and features of the present invention are combined in a predetermined form. Each component or feature shall be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. It is also possible to construct embodiments of the present invention by combining some of the elements and / or features. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is clear that the claims that are not expressly cited in the claims may be combined to form an embodiment or be included in a new claim by an amendment after the application.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

100: wireless communication system 110: macro base station
130: Small cell base station 131, 133: License band terminal
150: WiFi AP 151, 153: Non-licensed band terminal
600: base station 610: transceiver
630: Processor 650: Memory

Claims (10)

A method for supporting a License-Assisted Access (LAA) in a wireless communication system,
Selecting a license band terminal to perform the license support connection based on a delay time experienced by the license terminal in performing the license support connection and a time delay QoS of the license band terminal; And
A contention window of a contention window to be applied to the selected license band terminal by applying a proportional fair algorithm based on a yield of each of the non-license band terminal in communication and the selected license band terminal in the coverage of the base station, And determining the size of the license. The method according to claim 1,
Wherein the step of selecting a licensed band terminal to perform the license support connection comprises:
Estimating the number of non-licensed band terminals in communication within the coverage of the base station;
A minimum delay time to be experienced when the license-enabled terminal performs the license support connection based on the minimum contention window size among the estimated number of non-license-band terminals, the number of license-band terminals, and a predetermined contention window size step; And
Selecting a terminal whose time delay QoS of the license band terminal is larger than the calculated minimum delay time among the license band terminals. 3. The method of claim 2,
Wherein estimating the number of non-license-
A method of supporting a license support connection using an RF fingerprinting method. The method according to claim 1,
Wherein the step of determining the size of the contention window comprises:
The size of the contention window for maximizing the sum of the logarithms of the yields of the non-licensed band terminal and the selected license band terminal in the coverage of the base station is determined as the size of the contention window to be applied to the selected license band terminal , How to support access to license support. The method according to claim 1,
Further comprising the step of determining whether to grant a license support connection to the selected license band terminal based on the rate of performance degradation of the non-licensed band terminal resulting from the license support connection. 6. The method of claim 5,
Wherein the step of determining whether to grant the license support connection comprises:
Calculating a first yield of the non-licensed band terminal if the non-licensed band terminal only performs non-licensed band communication;
Calculating a second yield of the non-licensed band terminal when the non-licensed band terminal and the selected licensed band terminal perform non-licensed band communication; And
And determining that the selected license band terminal performs a license support connection only when the rate of decrease of the second yield with respect to the first yield is within a predetermined range. The method according to claim 1,
Wherein the license-bandwidth terminal is an LTE (Long Term Evolution) terminal and the non-license-band terminal is a Wi-Fi terminal. 1. A base station supporting a License-Assisted Access (LAA) in a wireless communication system,
A transceiver for communicating with a licensed band terminal; And
And a processor coupled to the transceiver,
The processor comprising:
Selecting a license band terminal to perform a license support connection based on the delay time experienced by the license terminal in performing the license support connection and the time delay QoS of the license band terminal,
A contention window of a contention window to be applied to the selected license band terminal by applying a proportional fair algorithm based on a yield of each of the non-license band terminal in communication and the selected license band terminal in the coverage of the base station, A license-aided access support base station configured to determine a size. 9. The method of claim 8,
The processor comprising:
Further comprising determining whether to grant a license support connection to the selected license band terminal based on the rate of performance degradation of the non-licensed band terminal resulting from the license support connection. A method for performing a License-Assisted Access (LAA) in a wireless communication system,
Receiving information on whether or not a license support connection is permitted from a base station and a size of a contention window to be applied when the license support is connected;
Sensing a carrier in a non-licensed band; And
And if the carrier is sensed in the non-licensed band, performing a random back-off within the contention window size and again sensing,
The size of the contention window
A license bandwidth terminal which is selected based on a delay time to be experienced by the license terminal in performing the license support connection and a time delay quality of service (QoS) of the license bandwidth terminal and each of the non-license band terminals communicating within the coverage of the base station A method of performing a license support connection, determined by applying a proportional fair algorithm based on yield.
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Citations (1)

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