KR20220063909A - Method and Apparatus for Supporting Low Latency Handover in Unlicensed Band Communication System - Google Patents

Abstract

Disclosed are a method and an apparatus for supporting low-latency handover in an unlicensed band communication system. According to one aspect of the present disclosure, a handover support method for supporting low latency handover of a terminal in an unlicensed band communication system includes the steps of: receiving first information for authentication between the terminal and a target access point (AP) from the terminal by a source AP being connected to the terminal; tunneling, by the source AP, the first information and transmitting the first information to the target AP; receiving, by the source AP, second information tunneled by the target AP; and reconfiguring, by the source AP, a frame structure of the second information and delivering the same to the terminal.

Description

Method and Apparatus for Supporting Low Latency Handover in Unlicensed Band Communication System

The present disclosure relates to a method and apparatus for supporting low-delay handover in an unlicensed band communication system.

The content described in this section merely provides background information on the present invention and does not constitute the prior art.

A wireless LAN is a technology developed for communication in a small indoor area. Recently, wireless LAN technology supports handover between APs through Multi-AP technology, which manages multiple access points (APs) as one network, in order to reduce indoor shadow areas and provide a low level of mobility. are doing Furthermore, in order to reduce delay during inter-AP handover, 802.11v BSS Transition Management (BTM) protocol and 802.11r Fast BSS Transition (FT) protocol have been proposed.

In the conventional wireless LAN technology, when a terminal moves from an existing AP to another AP, it takes a long time for an interruption because it performs a scanning and security authentication process after terminating the connection with the existing AP. There is a problem. To solve this problem, the BTM protocol reduces the time required for scanning by providing information about the AP adjacent to the terminal by the existing AP, and the FT protocol hierarchically manages the security keys of the adjacent APs when moving between APs. Reduce the delay in the authentication process.

However, since the conventional FT protocol reduces authentication delay on the premise that APs located in a small area know information about adjacent APs by communicating directly with each other, direct communication between APs, such as a long straight line There is a problem in that it cannot be applied to an environment where wireless communication is difficult.

An object of the present disclosure is to provide a low-delay handover support method and apparatus in an unlicensed band communication system, which can reduce delay during handover between APs in an environment where direct wireless communication between APs is impossible.

According to one aspect of the present disclosure, as a method for supporting low latency handover of a terminal in a license-exempt band communication system, a source AP (source access point) connected to the terminal is connected to the terminal from the terminal and Receiving first information for authentication between target APs (target access points); transmitting, by the source AP, the first information to the target AP by tunneling; receiving, by the source AP, second information tunneled by the target AP; and the source AP reconstructs the frame structure of the second information and transmits it to the terminal.

According to another aspect of the present disclosure, in the unlicensed band communication system, as a method for a terminal to perform a low latency handover, when the terminal satisfies a preset handover preparation condition, the terminal is in connection with the terminal a process of requesting information on a target access point (AP) to which the terminal will move access to a source access point (AP); receiving information on the target AP from the source AP; generating a master key for authentication with the target AP in cooperation with the source AP; and generating a temporary key to be used for data transmission/reception with the target AP in cooperation with the target AP when the terminal satisfies a preset radio link connection condition.

According to another aspect of the present disclosure, as a train communication system supporting low latency handover of a terminal provided in a train, and receiving first information for authentication between the terminal and the target AP from the terminal, a source AP (source access point) for transmitting the first information to the target AP by tunneling; a target AP (target access point) that generates second information for authentication between the terminal and the target AP, and transmits the second information to the terminal by tunneling the second information; It provides a train communication system comprising a controller that receives the tunneled information from the source AP or the target AP, and forwards the tunneled information to another controller or an AP controlled by itself.

According to another aspect of the present disclosure, in the unlicensed band communication system, as a terminal performing low latency handover, when the terminal satisfies a preset handover preparation condition, a source AP connected to the terminal a target AP information obtaining unit for requesting information on a target AP (target access point) to which the terminal will move access from a source access point and receiving information on the target AP from the source AP; a master key generation unit for generating a master key for authentication with the target AP in cooperation with the source AP; and a temporary key generator for generating a temporary key to be used for data transmission/reception with the target AP in conjunction with the target AP when the terminal satisfies a preset radio link connection condition.

As described above, according to the embodiment of the present disclosure, the time required for handover can be shortened by performing the authentication process for the target AP in advance.

Furthermore, according to an embodiment of the present disclosure, by using the internal network communication of the train communication system, the authentication process for the target AP can be performed in advance even in an environment where direct wireless communication between APs is impossible.

1 is an exemplary view for explaining a train communication system according to an embodiment of the present disclosure.
2 is a flowchart illustrating a low-delay handover method using internal network communication of a train communication system according to an embodiment of the present disclosure.
3 is a block diagram schematically illustrating a terminal according to an embodiment of the present disclosure.

Hereinafter, some embodiments of the present disclosure will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated on different drawings. In addition, in describing the present disclosure, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present disclosure, the detailed description thereof will be omitted.

In addition, in describing the components of the present disclosure, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, or order of the elements are not limited by the terms. Throughout the specification, when a part 'includes' or 'includes' a certain element, this means that other elements may be further included, rather than excluding other elements, unless otherwise stated. . In addition, the '... Terms such as 'unit' and 'module' mean a unit that processes at least one function or operation, which may be implemented as hardware or software or a combination of hardware and software.

The present disclosure may be described with reference to IEEE 1905.1 and IEEE 802.11, but this is for convenience of description and does not limit various embodiments of the present disclosure.

1 is an exemplary view for explaining a train communication system according to an embodiment of the present disclosure.

A train communication system according to an embodiment of the present disclosure includes a wireless LAN terminal (STA: station 100), an access point (AP: Access Point, 110 to 117), an agent (agent) 120 to 127, and a controller (controller) 130 and 135) in whole or in part.

The APs 110 to 117 are base stations that communicate with the wireless LAN terminal 100 provided in the train. As the train travels on the track, the WLAN terminal performs handover from the currently accessed AP to another AP.

The APs 110 to 117 may be controlled by different controllers 130 and 135 depending on the area in which they are located. For example, referring to FIG. 1 , AP A-1 110 to AP A-3 112 are controlled by controller A 130 , and AP B-1 115 to AP B-3 117 . may be controlled by controller B 135 .

The controllers 130 and 135 are logical entities, and may request and store information on APs connected to the controller, identification information of a terminal connected to each AP, channel information of a terminal connected to each AP, and the like.

Specifically, the controllers 130 and 135 are entities of an abstraction layer (AL) defined in the IEEE 1905.1 standard. Since the controllers 130 and 135 are logical entities, they are not limited by physical devices. That is, the controllers 130 and 135 may be implemented in the same device as each of the APs 110 to 117 or may be implemented in a device directly connected to the APs 110 to 117 .

The controllers 130 and 135 request or transmit information on the WLAN by exchanging messages with the agents 120 to 127 directly connected to the APs 110 to 117, and the APs 110 to 117 and/or The wireless LAN terminal 100 may command to perform a specific operation. The controllers 130 and 135 and the agents 120 to 127 exchange information using a message format defined in the IEEE 1905.1 standard. Hereinafter, a message conforming to the message format defined in the IEEE 1905.1 standard is referred to as a 1905.1 message.

The agents 120 to 127 may trigger a specific WLAN operation of the APs 110 to 117 connected thereto based on the 1905.1 message exchanged with the controllers 130 and 135 . In addition, the agents 120 to 127 may transmit information received from the APs 110 to 117 to the controllers 130 and 135 using the 1905.1 message.

Each of the agents 120 to 127 and the controllers 130 and 135 are identified using an ALMAC address, which is an identifier defined in the IEEE 1905.1 standard, and the APs 110 to 117 and the wireless LAN terminal 100 are IEEE 1905.1. It can be identified using a MAC address and a Basic Service Set IDentifier (BSSID) defined in the 802.11 standard.

According to an embodiment of the present disclosure, each of the controllers 130 and 135 is a WLAN terminal 100 in a WLAN network composed of agents 120 to 127 and/or APs 110 to 117 connected thereto. It can perform the role of Mobile Edge Computing (MEC) to support mobility by managing the connection and traffic of To this end, each of the controllers 130 and 135 may collect mobility information such as the speed and location of the train communicating with the APs 110 to 117 it controls.

The control server 140 is a server that manages the running of a train in a control room or a vehicle base, and includes an authentication server 150 in charge of security authentication of a wireless LAN terminal.

Hereinafter, it is assumed that the wireless LAN terminal 100 supports the FT (Fast BSS Transition) protocol, and an authentication process based on the FT security key hierarchy will be described, but this is for convenience of description and in this example It is not limited.

The authentication server 150 is a top-level subject of security key management, and generates and manages top-level security keys (eg, Master Session Key (MSK) and/or Master Pairwise Master Key (MPMK)).

Each of the controllers 130 and 135 receives the highest security key through authentication with the authentication server 150, and generates and manages a PMK-R0 (first level pairwise master key) based on this. PMK-R0 is managed individually for each WLAN terminal, and is generated based on a controller identifier, an STA identifier, and a random number. On the other hand, the wireless LAN terminal 100 provided in the train generates the first PMK-R0 through wired/wireless communication with the controller first connected to the vehicle base, etc., and stores the generated PMK-R0 as PMK-S0.

The controllers 130 and 135 transmit the PMK-R0 generated by themselves to the APs 110 to 117 connected to the WLAN terminal 100, and the APs 110 to 117 receive the PMK-R0, AP identifier, and STA. A second level Pairwise Master Key (PMK-R1) is generated using the identifier. In the same process, the wireless LAN terminal 100 generates PMK-R1 and stores it as PMK-S1.

Finally, the wireless LAN terminal 100 and the APs 110 to 117 use PMK-R1 to generate a PTK (Pairwise Transient Key) and use it for encryption of data transmission.

Therefore, when the wireless LAN terminal 100 moves to an AP different from the AP it is currently accessing, the wireless LAN terminal 100 must go through the above series of processes to generate a new PTK to be used for data transmission with the AP. , until the PTK is created, a frame for data transmission other than a frame for authentication and connection establishment cannot be transmitted to the corresponding AP.

According to an embodiment of the present disclosure, the wireless LAN terminal 100 and/or the controllers 130 and 135 provided in the train are provided from an on-vehicle or ground position detection device, GPS, tachometer, etc. The real-time location and speed of the train can be determined by using the acquired information, and the target AP to which the wireless LAN terminal 100 will connect can be selected using this. Accordingly, the wireless LAN terminal 100 may reduce the time required for handover by performing an authentication process for the target AP in advance.

In addition, according to an embodiment of the present disclosure, communication and security between the control server 140 , the controllers 130 and 135 , the agents 120 to 127 , and the APs 110 to 117 are preset in the train communication system. , even if the wireless LAN terminal 100 is located outside the range in which wireless communication with the target AP is possible, the above-described authentication process can be performed in advance by using the internal network communication of the train communication system.

Furthermore, according to an embodiment of the present disclosure, even in a controller handover situation in which the control range of a specific controller (eg, controller B) is transferred to the control range of another controller (eg, controller A) as the train moves, the train communication system By using the internal network communication of the above-mentioned authentication process can be performed in advance.

2 is a flowchart illustrating a low-delay handover method using internal network communication of a train communication system according to an embodiment of the present disclosure.

The terminal determines whether to start the handover preparation procedure based on the preset handover preparation condition (S200). Specifically, the terminal checks whether the speed and/or location of the current train satisfies a preset handover preparation condition. Here, the preset handover preparation conditions are the movement speed of the train, the distance between the train and the currently connected AP (hereinafter referred to as the source AP), the distance between the train and the target AP, and the received signal strength of the signal received from the source AP. indication, RSSI) and a condition related to at least one of a received signal strength of a signal received from the target AP. For example, the terminal may initiate a handover preparation procedure when the distance between the train and the source AP increases by more than a preset threshold distance, or when the distance between the train and the target AP approaches less than or equal to the preset threshold distance. In this case, the preset threshold distance may be set in consideration of the real-time speed of the train.

Meanwhile, according to another embodiment of the present disclosure, the controller and/or the source AP may determine whether to initiate the handover preparation procedure. In order to determine whether to start the handover preparation procedure, the controller and/or the source AP may acquire real-time location information and speed information of the train from the train or the control server. In this case, the train and/or the control server may acquire real-time location information and speed information of the train from sensors mounted inside and outside the train. Furthermore, the controller may obtain information on the received signal strength of the terminal connected to each AP from the AP (or agent) it controls.

When the handover preparation procedure is started, the terminal requests information on the target AP to which the terminal will access next to the source AP from the source AP (S210). According to an embodiment of the present disclosure, the UE may request information on the target AP by transmitting a neighbor report request frame to the source AP.

As a response to the neighbor report request, the source AP transmits a neighbor report response frame including information on the target AP to the UE (S220). In this case, the information on the target AP may include location information of the target AP and information (R1KH-ID) serving as an identifier as a PMK R1 key holder of the target AP, and R1KH-ID is the target AP. It may be a MAC address or a Basic Service Set Identifier (BSSID).

Meanwhile, the source AP may select a target AP based on a train route, a frequency band of a terminal provided in the train, a type of train, and the like. That is, even for trains traveling on the same route, different target APs may be selected depending on whether the train is an express train or a high-speed train and the situation of a platform. For example, when the train is a high-speed train, a handover may be performed by skipping a specific AP among APs existing on the travel path of the train. Furthermore, when the train has multiple STAs to use multiple frequency bands, the source AP selects a different target AP based on which frequency band the STA performs handover because propagation characteristics in each frequency band are different. can do.

Upon receiving the information on the target AP, the terminal transmits a frame requesting to perform authentication with the target AP for handover to the target AP to the source AP (S214). Here, the frame requesting to perform authentication with the target AP may be an FT request frame.

The source AP performs tunneling to deliver the received FT request frame to the target AP. Specifically, the source AP parses the received FT request frame and uploads it to an upper layer. The agent of the abstraction layer generates a 1905.1 message including the received FT request frame as a payload so that it can be delivered to the target AP. At this time, since a direct link may not be established between the source AP and the target AP, the source AP sets the destination of the 1905.1 message to the ALMAC address of the target AP (or agent), and sets the message to the 1905.1 link with itself. It is transmitted to the current controller (S222).

The controller transfers the received message to the target AP (or agent) with which the 1905.1 link is established with itself (S224). All 1905.1 messages used for tunneling in this disclosure request a 1905.1 acknowledgment (acknowledgement). If the 1905.1 message sender does not receive an acknowledgment response within a certain period of time after sending the 1905.1 message, the 1905.1 message sender retransmits the 1905.1 message. Here, the 1905.1 message sender may be an agent or a controller, and the AP and the terminal do not participate in the retransmission operation in the 1905.1 message transmission process.

Upon receiving the FT request frame through 1905.1 tunneling, the target AP generates an FT confirm frame including an anonce (Authenticator Nonce) based on the FT protocol, and delivers the FT confirm frame to the terminal through 1905.1 tunneling. do. At this time, the target AP (or agent) includes the FT acknowledgment frame in the 1905.1 message and transmits it to the controller (S230), and the controller forwards the 1905.1 message to the source AP (or agent) (S232).

Upon receiving the tunneled 1905.1 message, the source AP reconstructs the FT request frame included in the message into an 802.11 frame and transmits it to the terminal (S234).

Upon receiving the FT acknowledgment frame, the UE generates a snonce (supplicant nonce), and based on the combination of the anonce included in the FT acknowledgment frame and the generated snonce, generates PMK-R1 for authentication with the target AP (S240). The terminal temporarily stores the generated PMK-R1.

The UE transmits an FT response frame including the generated Snonce to the source AP (S250), and the source AP tunnels the FT response frame in the same manner as described above to provide the FT Ack frame to the target AP. is transmitted by tunneling (S252 and S254).

The target AP generates PMK-R1 for authentication with the UE by using Anonce and Snonce (S260). The target AP temporarily stores the generated PMK-R1.

The terminal and/or the controller determines whether a stable radio link connection between the terminal and the target AP is possible based on a preset radio link connection condition (S270). Here, the preset wireless link connection condition may be a condition related to the moving speed of the train and the distance between the train and the target AP. For example, when the distance between the train and the target AP approaches a preset threshold distance or less, it may be determined that a stable wireless link connection between the terminal and the target AP is possible. In this case, the preset threshold distance may be set in consideration of the real-time speed of the train, and may be set to a value different from the threshold distance for determining whether to start the handover preparation procedure.

That is, according to an embodiment of the present disclosure, before the condition for a stable radio link connection between the terminal and the target AP is satisfied, the terminal and the target AP perform processes S210 to S260 to generate and store PMK-R1. Handover preparation conditions and radio link connection conditions can be set for this purpose. For example, when the distance between the train and the target AP becomes less than or equal to the first threshold distance, the handover preparation procedure is started, and when the distance between the train and the target AP is less than or equal to the second threshold distance that is smaller than the first threshold distance, the radio link connection procedure can be initiated.

Furthermore, according to an embodiment of the present disclosure, the preset radio link connection condition may be a condition that additionally considers the received signal strength of a signal received from the target AP. For example, when the distance between the train and the target AP is a preset threshold distance and the RSSI of a signal received by the terminal from the target AP is greater than or equal to the preset threshold strength, the terminal and/or the controller establishes a stable radio link connection between the terminal and the target AP It can be considered that this is possible.

Meanwhile, when the controller determines that a stable radio link connection between the terminal and the target AP is possible, the controller may instruct the terminal to handover by using a steering request message. Specifically, the controller transmits a steering request message instructing the UE to move to the target AP to the source AP (or agent), and the source AP causes the UE to attempt an association change to the target AP. BTM request frame (BTM request frame) is transmitted to the terminal.

When the radio link connection procedure is started, the terminal transmits a reassociation request frame to the target AP (S280), and receives a reassociation response frame from the target AP (S282). In the process of transmitting and receiving the reconnection request frame and the reconnection response frame, the terminal and the target AP generate a PTK (Pairwise Transient Key) and GTK (Group Temporal Key) to complete setting of an encryption key used for data transmission and reception.

As described above, according to an embodiment of the present disclosure, since the terminal can receive information about the identifier and the operation channel of the target AP in the process of the neighbor report request and response process (S210 and S212), unnecessary scanning process can be omitted. Therefore, conditions for reassociation with the target AP can be set based on the position and speed of the train, and when the condition is satisfied, reconnection to the target AP can be performed directly without performing a scanning process.

3 is a block diagram schematically illustrating a terminal according to an embodiment of the present disclosure.

3, the terminal 100 according to an embodiment of the present disclosure includes an authentication initiation unit 300, a target AP information acquisition unit 310, and a master key generation unit ( The master key generation unit 320, an association initiation unit 330, and a temporary key generation unit (transient key generation unit, 340) all or in part. Not all blocks shown in FIG. 3 are essential components, and in another embodiment, some blocks included in the terminal may be added, changed, or deleted. That is, in the case of FIG. 3, prior to the terminal performing the radio link connection with the target AP, the component for reducing the handover delay time by performing a pre-authentication procedure according to an embodiment of the present disclosure is exemplarily shown As one thing, it should be recognized that the terminal 100 may have more or fewer components or different components than those shown for the implementation of other functions.

The authentication initiator 300 determines whether to start a handover preparation procedure, that is, an authentication procedure, based on a preset handover preparation condition. Here, the preset handover preparation condition is at least one of the moving speed of the train, the distance between the train and the source AP, the distance between the train and the target AP, the received signal strength of the signal received from the source AP, and the received signal strength of the signal received from the target AP. It can be a condition related to one.

The target AP information obtaining unit 310 obtains information on the target AP from the source AP. Specifically, when the handover preparation procedure is started, the terminal requests information on the target AP to which the access is to be transferred from the source AP being accessed, and receives information on the target AP from the source AP. In this case, the information on the target AP may include location information of the target AP and information (R1KH-ID) serving as an identifier as a PMK R1 key holder of the target AP, and R1KH-ID is the target AP. It may be a MAC address or a Basic Service Set Identifier (BSSID). Meanwhile, according to an embodiment of the present disclosure, the target AP information obtaining unit 310 transmits a neighbor report request frame to the source AP, and in response thereto, receives information on the target AP from the source AP. A neighbor report response frame including a neighbor report response frame may be received.

The master key generator 320 works with the source AP to generate a master key for authentication with the target AP. Specifically, the master key generator 320 may exchange information with the target AP via at least one of a source AP, a controller controlling the source AP, and a controller controlling the target AP through 1905.1 tunneling. The master key generation unit 320 transmits and receives an FT request frame, an FT confirm frame, and an FT Ack frame with the target AP through 1905.1 tunneling, and transmits and receives the FT Ack frame to the corresponding frame. PMK-R1 is generated based on the included information.

The connection initiator 330 determines whether a stable wireless link connection between the terminal and the target AP is possible based on a preset wireless link connection condition. The preset wireless link connection condition may be a condition related to the moving speed of the train and the distance between the train and the target AP.

The temporary key generator 340 generates a temporary key to be used for data transmission/reception with the target AP in cooperation with the target AP. Specifically, when a stable wireless link connection between the terminal and the target AP is possible, the temporary key generator 340 transmits a reassociation request frame to the target AP, and a reassociation response frame from the target AP. receive In the process of transmitting and receiving the reconnection request frame and the reconnection response frame, the temporary key generation unit 340 generates a PTK (Pairwise Transient Key) and a GTK (Group Temporal Key) to complete setting of an encryption key used for data transmission and reception.

Although it is described that each process is sequentially executed in FIG. 2 , this is merely illustrative of the technical idea of an embodiment of the present disclosure. In other words, those of ordinary skill in the art to which an embodiment of the present disclosure pertain may change the order described in FIG. 2 without departing from the essential characteristics of an embodiment of the present disclosure or perform one or more of the respective processes. Since it will be possible to apply various modifications and variations by executing in parallel, FIG. 2 is not limited to a time-series order.

Various implementations of the systems and techniques described herein may be implemented in digital electronic circuitry, integrated circuitry, field programmable gate array (FPGA), application specific integrated circuit (ASIC), computer hardware, firmware, software, and/or combination can be realized. These various implementations may include being implemented in one or more computer programs executable on a programmable system. The programmable system includes at least one programmable processor (which may be a special purpose processor) coupled to receive data and instructions from, and transmit data and instructions to, a storage system, at least one input device, and at least one output device. or may be a general-purpose processor). Computer programs (also known as programs, software, software applications or code) contain instructions for a programmable processor and are stored on a "computer-readable recording medium".

The computer-readable recording medium includes all types of recording devices in which data readable by a computer system is stored. These computer-readable recording media are non-volatile or non-transitory, such as ROM, CD-ROM, magnetic tape, floppy disk, memory card, hard disk, magneto-optical disk, and storage device. It may be a medium, and may further include a transitory medium such as a data transmission medium. In addition, the computer-readable recording medium may be distributed in a network-connected computer system, and the computer-readable code may be stored and executed in a distributed manner.

Various implementations of the systems and techniques described herein may be implemented by a programmable computer. Here, the computer includes a programmable processor, a data storage system (including volatile memory, non-volatile memory, or other types of storage systems or combinations thereof), and at least one communication interface. For example, a programmable computer may be one of a server, a network appliance, a set-top box, an embedded device, a computer expansion module, a personal computer, a laptop, a Personal Data Assistant (PDA), a cloud computing system, or a mobile device.

The above description is merely illustrative of the technical idea of this embodiment, and various modifications and variations will be possible without departing from the essential characteristics of the present embodiment by those skilled in the art to which this embodiment belongs. Accordingly, the present embodiments are intended to explain rather than limit the technical spirit of the present embodiment, and the scope of the technical spirit of the present embodiment is not limited by these embodiments. The protection scope of this embodiment should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present embodiment.

10: train communication system 100: wireless LAN terminal
110 to 117: access point 120 to 127: agent
130 and 135: controller 140: control server
150: authentication server

Claims (14)

As a method for supporting low latency handover of a terminal in an unlicensed band communication system,
a process in which a source access point (AP) being accessed with the terminal receives first information for authentication between the terminal and a target access point (AP) from the terminal;
transmitting, by the source AP, the first information to the target AP by tunneling;
receiving, by the source AP, second information tunneled by the target AP; and
A process in which the source AP reconstructs the frame structure of the second information and transmits it to the terminal
Handover support method comprising a. According to claim 1,
generating, by the target AP, a pairwise master key (PMK) for the terminal based on the first information and the second information; and
When the terminal and the target AP satisfy a preset radio link connection condition, the target AP performs a reassociation procedure in conjunction with the terminal
Handover support method, characterized in that it further comprises. According to claim 1,
The process of delivering to the target AP is,
a process in which the source AP parses the first information and transmits it to a source agent;
generating, by the source agent, a first message including the first information as a payload, and transmitting the first message to a controller controlling the source AP; and
The process in which the controller transmits the first message to the target AP or a controller controlling the target AP
Handover support method comprising a. 4. The method of claim 3,
The first message is
A handover support method, characterized in that the target AP or an ALMAC address of a target agent connected to the target AP is used as a destination. According to claim 1,
The process of receiving the second information,
The method for supporting handover, characterized in that the source AP receives a second message including the second information as a payload from a controller controlling the source AP. The method of claim 1,
The first information is
Including an FT request frame or FT acknowledgment frame generated by the terminal,
The second information is
A handover support method comprising an FT confirm frame generated by the target AP. The method of claim 1,
Before the process of receiving the first information,
A process of determining whether to start a handover preparation procedure for the terminal based on a preset handover preparation condition
receiving, by the source AP, a request for information on a target AP from the terminal when a handover preparation procedure for the terminal is started; and
A process in which the source AP transmits information on the target AP to the terminal
Handover support method, characterized in that it further comprises. 8. The method of claim 7,
The preset handover preparation condition is:
The movement speed of the terminal, the distance between the terminal and the source AP, the distance between the terminal and the target AP, Received Signal Strength Indication (RSSI) between the terminal and the source AP, and the terminal and the target AP A handover support method, characterized in that the condition is related to at least one of the received signal strengths between the two. 3. The method of claim 2,
The preset wireless link connection condition is:
A handover support method, characterized in that the condition is related to at least one of a movement speed of the terminal, a distance between the terminal and the target AP, and a received signal strength between the terminal and the target AP. 3. The method of claim 2,
Before performing the reconnection procedure,
transmitting, by a controller controlling the source AP, a steering request frame to the source AP when the terminal and the target AP satisfy a preset radio link connection condition; and
A process in which the source AP receiving the steering request frame instructs the terminal to perform a reconnection procedure by transmitting a BTM request frame to the terminal
Handover support method, characterized in that it further comprises. In the unlicensed band communication system, as a method for a terminal to perform a low latency handover,
when the terminal satisfies a preset handover preparation condition, requesting information about a target access point (AP) to which the terminal will move access from a source AP (source access point) being accessed with the terminal;
receiving information on the target AP from the source AP;
generating a master key for authentication with the target AP in cooperation with the source AP; and
A process of generating a temporary key to be used for data transmission/reception with the target AP by interworking with the target AP when the terminal satisfies a preset radio link connection condition
Handover method comprising a. 12. The method of claim 11,
The process of generating the master key is
A handover method, characterized in that it is performed before the terminal satisfies the preset radio link connection condition. As a train communication system that supports low latency handover of terminals provided in trains,
a source AP (source access point) for receiving first information for authentication between the terminal and the target AP from the terminal, and transmitting the first information to the target AP by tunneling the first information;
a target AP (target access point) for generating second information for authentication between the terminal and the target AP, and transmitting the second information to the terminal by tunneling the second information;
A controller that receives tunneled information from the source AP or the target AP, and forwards the tunneled information to another controller or an AP it controls
A train communication system comprising a. In the unlicensed band communication system, as a terminal performing low latency handover,
When the terminal satisfies the preset handover preparation condition, the terminal requests information about a target access point (AP) to which the terminal will move access from a source AP (source access point) that is accessing the terminal, and the source AP a target AP information obtaining unit for receiving information on the target AP from;
a master key generation unit for generating a master key for authentication with the target AP in cooperation with the source AP; and
When the terminal satisfies a preset radio link connection condition, a temporary key generator for generating a temporary key to be used for data transmission/reception with the target AP in conjunction with the target AP
A terminal comprising a.

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