KR20210036637A - Method for client steering in multi-ap wireless lan networks - Google Patents

Abstract

Provided is a steering method in a multi-access point (MAP) wireless local area network (WLAN) environment to perform efficient data transmission/reception operation. According to one embodiment of the present invention, the steering method comprises the following steps of: determining whether a terminal performs steering; evaluating WLAN performance between at least one basic service set (BSS) included in a MAP WLAN and the terminal; selecting a target BSS to be newly accessed by the terminal on the basis of an evaluation result; and triggering steering so that the terminal accesses the target BSS. The step of selecting the target BSS allows a controller to select the target BSS on the basis of a self-score which is a WLAN performance evaluation score between a parent BSS, which is a BSS to which the terminal is connected, and the terminal, a target score which is a WLAN performance evaluation score between the BSSs except for the parent BSS and the terminal, and a preset steering start limit value.

Description

Terminal steering method in multi-base station wireless LAN environment {METHOD FOR CLIENT STEERING IN MULTI-AP WIRELESS LAN NETWORKS}

The present invention relates to a method for improving transmission efficiency, and more particularly, to various methods, apparatuses, and systems for improving transmission efficiency by proposing an improved channel access method in a wireless LAN.

Recently, as the spread of mobile devices expands, a wireless LAN technology capable of providing fast wireless Internet service to them is in the spotlight. Wireless LAN technology is a technology that allows mobile devices such as smart phones, smart pads, laptop computers, portable multimedia players, embedded devices, etc. to access the Internet wirelessly at home, business, or in a specific service area based on wireless communication technology in a short distance. to be.

Since IEEE (Institute of Electrical and Electronics Engineers) 802.11 supported the initial wireless LAN technology using 2.4GHz frequency, various technology standards are being commercialized or developed. First, IEEE 802.11b supports a communication speed of up to 11Mbps while using a frequency of the 2.4GHz band. IEEE 802.11a, commercialized after IEEE 802.11b, has reduced the effect of interference compared to the frequency of the 2.4GHz band, which is quite congested by using the frequency of the 5GHz band instead of the 2.4GHz band, and uses OFDM technology to maximize the communication speed. It has been improved to 54Mbps. However, IEEE 802.11a has a short communication distance compared to IEEE 802.11b. And IEEE 802.11g, like IEEE 802.11b, implements a communication speed of up to 54Mbps using a frequency of the 2.4GHz band, and has received considerable attention because it satisfies backward compatibility. Have the upper hand.

In addition, IEEE 802.11n is a technical standard established to overcome the limitation on communication speed, which has been pointed out as a vulnerability in wireless LAN. IEEE 802.11n aims to increase the speed and reliability of the network and extend the operating distance of the wireless network. More specifically, IEEE 802.11n supports high throughput (HT) with a data processing rate of up to 540 Mbps or more, and uses multiple antennas at both ends of the transmitter and receiver to minimize transmission errors and optimize the data rate. It is based on MIMO (Multiple Inputs and Multiple Outputs) technology. In addition, this standard can use a coding scheme in which multiple duplicate copies are transmitted to increase data reliability.

As the widespread use of wireless LANs is active and applications using them are diversified, the need for a new wireless LAN system to support a higher throughput (Very High Throughput, VHT) than the data processing speed supported by IEEE 802.11n emerges. Became. Among them, IEEE 802.11ac supports a wide bandwidth (80MHz~160MHz) at 5GHz frequency. The IEEE 802.11ac standard is defined only in the 5GHz band, but for backward compatibility with existing 2.4GHz band products, the initial 11ac chipsets will also support operation in the 2.4GHz band. In theory, according to this standard, the wireless LAN speed of multiple stations is at least 1 Gbps and the maximum single link speed is at least 500 Mbps. This is achieved by extending the concept of air interfaces adopted by 802.11n, such as wider radio frequency bandwidth (up to 160 MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high-density modulation (up to 256 QAM). In addition, there is IEEE 802.11ad as a method of transmitting data using a 60GHz band instead of the existing 2.4GHz/5GHz. IEEE 802.11ad is a transmission standard that provides a maximum speed of 7Gbps using beamforming technology, and is suitable for high bit rate video streaming such as large amounts of data or uncompressed HD video. However, the 60GHz frequency band has a disadvantage that it is difficult to pass through obstacles and can only be used between devices in a short distance.

On the other hand, as the next generation wireless LAN standard after 802.11ac and 802.11ad, discussions are continuously being made to provide a high-efficiency and high-performance wireless LAN communication technology in a high density environment. That is, in a next-generation wireless LAN environment, high-frequency communication must be provided indoors/outdoors in the presence of a high-density station and an access point (AP), and various technologies have been developed to implement this.

Nevertheless, in the case of a wireless LAN, the communication distance is relatively short because a number of terminals form a network with one AP, and the user experience may be degraded due to the occurrence of a shadow area in the same space depending on the location of the AP. They have not been overcome until now. In order to solve the above problems, recently, a standard technology for increasing coverage and user experience by installing multiple APs (Multi-APs) capable of configuring the same network is actively discussed, focusing on the Wi-Fi Alliance (WFA). However, since the multi-AP technology is currently being discussed in an early stage, related technologies in various aspects need to be developed in the future.

An object of the present invention is to perform an efficient data transmission/reception operation in a multi-base station WLAN environment as described above.

According to an embodiment of the present invention, the step of determining, by a controller, whether or not a terminal connected to a multi-base station wireless LAN network performs steering; Evaluating, by the controller, a wireless LAN performance between at least one basic service set (BSS) included in a multi-base station wireless LAN network and the terminal; Selecting, by the controller, a target BSS (Basic Service Set) to be newly accessed by the terminal based on the evaluation result; And triggering, by the controller, a steering so that the terminal is connected to the target Basic Service Set (BSS), and the step of selecting the target Basic Service Set (BSS) comprises: the controller, the terminal The parent BSS (Basic Service Set), which is a basic service set (BSS) being accessed, and the self-score, which is a WLAN performance evaluation score between the terminal, and the parent BSS (Basic Service Set), and a target score that is a WLAN performance evaluation score between the terminal and a target BSS (Basic Service Set) based on a preset steering start limit value. A steering method in a base station wireless LAN environment may be provided.

Here, in the step of evaluating the WLAN performance, the controller individually calculates the self score and the target score based on at least one WLAN parameter or measured value, and selects the target BSS (Basic Service Set). In the step of, the controller selects a BSS (Basic Service Set) representing a target score greater than the sum of the self score and the steering start limit value as a target BSS (Basic Service Set).

Here, the steering start limit value is determined based on the size and type of data that the terminal is transmitting or receiving with a parent BSS (Basic Service Set).

Here, the step of selecting the target BSS (Basic Service Set) includes, by the controller, at least one additional steering condition based on the size and type of data being transmitted/received or scheduled to be transmitted/received by the terminal to a parent BSS (Basic Service Set). After selection, the target BSS (Basic Service Set) is selected based on whether or not the additional steering condition is satisfied.

Here, in the step of selecting the target BSS (Basic Service Set), the controller determines the highest score when there are two or more BSS (Basic Service Set) indicating target scores greater than the sum of the self score and the steering start limit value. The indicated BSS (Basic Service Set) is selected as a target BSS (Basic Service Set).

In a wireless LAN, an efficient data transmission/reception operation of a terminal can be performed through multiple base stations.

1 is a diagram showing a wireless LAN system according to an embodiment of the present invention.
2 is a diagram showing a wireless LAN system according to another embodiment of the present invention.
3 is a block diagram showing the configuration of a station according to an embodiment of the present invention.
4 is a block diagram showing the configuration of an access point according to an embodiment of the present invention.
5 shows a multi-base station wireless LAN network environment proposed in the present invention.
6 shows a logical structure of multiple base station devices according to an embodiment of the present invention.
7 to 8 are diagrams illustrating a connection relationship between a base station and a terminal included in a multi-base station WLAN network according to an embodiment of the present invention.
9 is a diagram showing a steering method according to an embodiment of the present invention.

The terms used in the present specification have been selected as currently widely used general terms as possible while considering functions in the present invention, but this may vary according to the intention, custom, or the emergence of new technologies of technicians in the field. In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, the meaning will be described in the description of the corresponding invention. Therefore, it should be noted that the terms used in the present specification should be interpreted based on the actual meaning of the term and the entire contents of the present specification, not a simple name of the term.

Throughout the specification, when a component is said to be “connected” with another component, this includes not only the case that it is “directly connected”, but also the case that it is “electrically connected” with another component in between. do. In addition, when a certain component "includes" a specific component, it means that other components may be further included rather than excluding other components unless specifically stated to the contrary. In addition, the limitations of "more" or "less than" based on a specific threshold value may be appropriately replaced with "excess" or "less than", respectively, depending on the embodiment. In addition, the term “terminal” may be replaced with words such as “client (or client terminal or client device)”, “station”, and “STA”. The term "base station" can be replaced with words such as "access point", "AP", and so on. In addition, “MAP controller” may be simply described as “controller” and “MAP agent” may simply be described as “agent”.

1 illustrates a wireless LAN system according to an embodiment of the present invention. The wireless LAN system includes one or more Basic Service Set (BSS), and the BSS represents a set of devices that can communicate with each other by successfully synchronizing. In general, the BSS can be classified into an infrastructure BSS (infrastructure BSS) and an independent BSS (IBSS), and FIG. 1 shows an infrastructure BSS among them.

1, the infrastructure BSS (BSS1, BSS2) provides one or more stations (STA-1, STA-2, STA-3, STA-4, STA-5), and distribution service. An access point (PCP/AP-1, PCP/AP-2), which is a providing station, and a distribution system (DS) that connects multiple access points (PCP/AP-1, PCP/AP-2). Includes.

A station (STA) is an arbitrary device including a medium access control (MAC) and a physical layer interface to a wireless medium in accordance with the IEEE 802.11 standard, and in a broad sense, a non-access point ( Non-AP) includes all stations as well as access points (APs). In addition, in the present specification, the term'terminal' may be used as a concept including all wireless LAN communication devices such as a station and an AP. The station for wireless communication includes a processor and a transceiver, and may further include a user interface unit and a display unit according to an embodiment. The processor may generate a frame to be transmitted through a wireless network or process a frame received through the wireless network, and may perform various other processes for controlling a station. In addition, the transceiver is functionally connected to the processor and transmits and receives frames through a wireless network for the station.

An Access Point (AP) is an entity that provides access to a distribution system (DS) via a wireless medium for a station associated with it. In an infrastructure BSS, communication between non-AP stations is in principle performed via an AP, but when a direct link is established, direct communication is also possible between non-AP stations. Meanwhile, in the present invention, the AP is used as a concept including a Personal BSS Coordination Point (PCP), and broadly, a centralized controller, a base station (BS), a node-B, a base transceiver system (BTS), or a site It may include all concepts such as a controller.

A plurality of infrastructure BSSs may be interconnected through a distribution system (DS). In this case, a plurality of BSSs connected through the distribution system is referred to as an extended service set (ESS).

2 illustrates an independent BSS, which is a wireless LAN system according to another embodiment of the present invention. In the embodiment of FIG. 2, duplicate descriptions of parts that are the same as or corresponding to the embodiment of FIG. 1 will be omitted.

Since the BSS-3 shown in FIG. 2 is an independent BSS and does not include an AP, all stations STA-6 and STA-7 are not connected to the AP. Independent BSS is not allowed to access the distribution system and forms a self-contained network. In the independent BSS, the stations STA-6 and STA-7 may be directly connected to each other.

3 is a block diagram showing the configuration of a station 100 according to an embodiment of the present invention.

As shown, the station 100 according to the embodiment of the present invention includes a processor 110, a network interface card (NIC, 120), a user interface unit 140, a display unit 150, and a memory 160. can do.

First, the network interface card 120 is a module for performing wireless LAN access, and performs packet transmission and reception for the station 100. The network interface card 120 may be built-in or externally provided in the station 100, and may include at least one network interface card module using different frequency bands according to embodiments. For example, the network interface card may include network interface card modules of different frequency bands such as 2.4GHz, 5GHz, and 60GHz. According to an embodiment, the station 100 may include a network interface card module using a frequency band of 6 GHz or higher and a network interface card module using a frequency band of 6 GHz or lower. Each network interface card module may perform wireless communication with an AP or an external station according to a wireless LAN standard of a frequency band supported by the corresponding network interface card module. The network interface card 120 may operate only one network interface card module at a time or may simultaneously operate a plurality of network interface card modules according to the performance and requirements of the station 100. When the station 100 includes a plurality of network interface card modules, each network interface card module may be provided in an independent form or may be integrated into one chip.

Next, the user interface unit 140 includes various types of input/output means provided in the station 100. That is, the user interface unit 140 may receive a user's input using various input means, and the processor 110 may control the station 100 based on the received user input. In addition, the user interface unit 140 may perform output based on a command of the processor 110 using various output means.

Next, the display unit 150 outputs an image on the display screen. The display unit 150 may output various display objects such as content executed by the processor 110 or a user interface based on a control command of the processor 110. In addition, the memory 160 stores a control program used in the station 100 and various data corresponding thereto. The control program may include an access program necessary for the station 100 to access an AP or an external station.

The processor 110 of the present invention may execute various commands or programs and process data inside the station 100. In addition, the processor 110 controls each unit of the station 100 described above, and may control data transmission/reception between the units. According to an embodiment of the present invention, the processor 110 may execute a program for accessing an AP stored in the memory 160 and receive a communication setup message transmitted by the AP. In addition, the processor 110 may read information on the priority condition of the station 100 included in the communication setup message, and request access to the AP based on the information on the priority condition of the station 100. A specific embodiment of this will be described later.

The station 100 shown in FIG. 3 is a block diagram according to an embodiment of the present invention, and the separated blocks are shown by logically distinguishing elements of a device. Accordingly, the elements of the above-described device may be mounted as one chip or as a plurality of chips according to the design of the device. In addition, in the embodiment of the present invention, some components of the station 100, such as the user interface unit 140 and the display unit 150, may be selectively provided in the station 100.

4 is a block diagram showing the configuration of an AP 200 according to an embodiment of the present invention.

As shown, the AP 200 according to an embodiment of the present invention may include a processor 210, a network interface card 220, and a memory 260. In FIG. 4, redundant descriptions of parts of the configuration of the AP 200 that are the same as or corresponding to the configuration of the station 100 of FIG. 3 will be omitted.

4, an AP 200 according to the present invention includes a network interface card 220 for operating a BSS in at least one frequency band. As described above in the embodiment of FIG. 3, the network interface card 220 of the AP 200 may also include a plurality of network interface card modules using different frequency bands. That is, the AP 200 according to an embodiment of the present invention may include two or more network interface card modules among different frequency bands, such as 2.4GHz, 5GHz, and 60GHz. Preferably, the AP 200 may include a network interface card module using a frequency band of 6 GHz or higher and a network interface card module using a frequency band of 6 GHz or lower. Each network interface card module may perform wireless communication with a station according to a wireless LAN standard of a frequency band supported by the corresponding network interface card module. The network interface card 220 may operate only one network interface card module at a time or may simultaneously operate a plurality of network interface card modules according to the performance and requirements of the AP 200.

Next, the memory 260 stores a control program used in the AP 200 and various data corresponding thereto. Such a control program may include an access program that manages the access of the station. In addition, the processor 210 controls each unit of the AP 200 and may control data transmission/reception between the units. According to an embodiment of the present invention, the processor 210 may execute a program for accessing a station stored in the memory 260 and transmit a communication setting message for one or more stations. In this case, the communication setup message may include information on the access priority condition of each station. In addition, the processor 210 performs connection setup according to the station's connection request. A specific embodiment of this will be described later.

5 shows a multi-base station wireless LAN network environment proposed in the present invention. In FIG. 5, a shaded circle (802.11 STA) refers to a WLAN terminal or a client device, a circle in which MAP is described refers to a multi-base station device (802.11 AP, MAP), and a solid line between multiple base station devices (MAP) refers to a backhaul. It means a link, and a dotted line between a multi-base station device (MAP) and a terminal means a fronthaul link.

A multi-base station WLAN network (Multi-AP (MAP) Network) environment may exist in the form of overlapping WLAN BSSs formed around one AP. However, unlike the existing wireless LAN networks of overlapping BSS, each network can establish a wireless LAN or Ethernet link (backhaul link) capable of communicating with each other. Therefore, in a multi-base station wireless LAN environment, each multi-base station device (MAP) can communicate with the external network through another MAP connected to the external network through a backhaul link, even if it is not directly connected to the external network (WAN). It is possible. In general, since MAP assumes that multiple RF modules that can be operated concurrently are installed, multiple BSSs can be operated at the same time. Therefore, it is possible to operate a Fronthaul BSS that can be accessed by a wireless LAN client device such as a user's smartphone or laptop, and a Backhaul BSS that can be accessed by another MAP constituting the same network. A MAP that is not connected to may access the backhaul BSS and communicate with an external network.

Each of the MAPs constituting the same MAP network has a different fronthaul BSSID and performs individual BSS operations, but since the same SSID is used and the same access security method is used, the entire MAP network is recognized as a single WLAN profile from the perspective of the user device. Can be.

6 shows a logical structure of multiple base station devices according to an embodiment of the present invention.

In the MAP network, in addition to basic functions such as signal amplifying and packet forwarding provided by the existing wireless LAN repeater or extender devices, it is intended to provide functions that intelligently cope with various situations occurring in the network by centralizing various information on the entire network. For example, when MAPs are in an overlapping space, a fronthaul BSS can be configured using a channel with the least interference or the best efficiency. In addition, when a new MAP device connects to a new existing MAP network (onboarding), users do not directly enter security-related information, form a backhaul link in a reliable way, and provide new configuration information such as SSID and credential. Can be delivered to MAP. Alternatively, when a client connected to a specific MAP moves, it is also possible to induce roaming by selecting an optimal MAP in consideration of channel change and BSS load.

In order to perform the above functions, client access information, channel information, client and AP capability information, etc. are concentrated, and a subject that processes the information and issues a command is required. To this end, the MAP standard defines a MAP controller to perform the above operations. The MAP controller can exist in only one entity in one MAP network, and since it is a logical entity, it may exist in devices directly connected to the MAP, such as MAP devices, switches, and gateways, regardless of physical devices. The MAP controller requests information related to the corresponding device from a MAP agent existing in each MAP device or executes a command related to a specific BSS or a specific client.

The 802.11-based wireless LAN standard does not define the function of transmitting information inside the BSS to an entity of 1-hop or more. Therefore, the MAP controller and agent are of the Abstraction Layer (AL) defined in the IEEE 1905.1 standard. Send and receive information using a messaging protocol. AL is a layer in the middle of Layer 2 (MAC) and Layer 3 (IP), and is defined for routing and messaging functions within a multihop network composed of heterogeneous links such as WLAN, Ethernet, and PLC. A message transmitted in the 1905.1 format can be delivered to a MAP agent located at multiple hop distances, and the transmitted information can be delivered to the MAC layer of a specific BSS of the corresponding MAP device. In addition, since each MAP agent knows the WAN access point in the MAP network through 1905.1 routing, the wireless LAN packet delivered by the client to the AP can be delivered to the WAN access point.

In the following description, “MAP controller” is simply described as “controller” and “MAP agent” is described as “agent”, and “station”, “client”, “STA”, “terminal”, etc. The terms of "terminal" should be unified as "terminal", and terms such as "access point", "AP", and "base station" should be unified as "base station".

7 to 8 are diagrams illustrating a connection relationship between a base station and a terminal included in a multi-base station WLAN network according to an embodiment of the present invention. According to FIGS. 7 to 8, one terminal 100 and two base stations 200A and 200B may be included in a multi-base station WLAN network. Here, whether each base station is a controller or an agent in a multi-base station wireless LAN network is not separately shown.In the embodiments of FIGS. 7 to 8, both base stations are agents, and the controller controlling the multi-base station wireless LAN network is It should be regarded as omitted and explained.

7 to 8, solid and dotted lines (C1 to C4) indicate a communication channel that can be used when the terminal 100 connects to the base stations 200A and 200B, or each BSS of the terminal 100 and the base stations 200A and 200B ( Basic Service Set). In the following description, each of C1 to C4 will be simply referred to as first BSS to fourth BSS, respectively.

Referring to FIG. 7, the terminal 100 is currently connected to each other through the first BSS (C1) of the base station 200A. Here, the BSS to which the terminal 100 is currently connected may be referred to as a parent BSS (Patent BSS). Accordingly, in FIG. 7, the first BSS C1 is a parent BSS. At this time, if the controller determines that the performance of the wireless LAN communication between the terminal 100 and the first BSS (C1) does not satisfy a preset criterion, the multi-base station so that the terminal 100 is connected to another BSS. The operation of each base station of the WLAN network can be controlled, and this is referred to as client steering ("steering"). However, steering may be implemented in various aspects, and steering according to an embodiment of the present invention is not limited thereto.

Here, the controller may set at least one BSS in the corresponding multi-base station WLAN network as a candidate BSS, and the BSS selected as a steering target among the candidate BSSs may be named as a target BSS (T_BSS). In the embodiment of FIG. 7, the first BSS to the fourth BSS may be candidate BSSs.

According to FIG. 8(a), the controller allows the terminal 100 to access the second BSS (C2), which is the same base station as in FIG. 7 but a completely different BSS. For example, if the first BSS (C1) is a wireless LAN channel using a 2.4 GHz band and the measured transmission rate is evaluated to be very low, the controller is the second BSS of the same base station using the 5 GHz band. Steering can be performed to connect to C2). In this case, the target BSS becomes the second BSS (C2).

Of course, steering can be performed for a base station completely different from the existing one. According to FIG. 8(b), the controller may cause the terminal 100 to access the third BSS (C3) of the base station 200B. In this case, the target BSS becomes the third BSS (C3).

9 is a diagram showing a steering method according to an embodiment of the present invention. Referring to FIG. 9, in a method for steering a terminal in a multi-base station wireless LAN environment, the controller may determine whether to perform steering of a terminal connected to the multi-base station wireless LAN network (S110). In addition, the controller may evaluate the wireless LAN performance between at least one basic service set (BSS) included in the multi-base station wireless LAN network and the terminal (S120). In addition, the controller may select a target BSS to be newly accessed by the terminal based on the evaluation result (S130). In addition, the controller may trigger steering (S140) so that the terminal is connected to the target Basic Service Set (BSS).

First, the controller may determine whether steering is required for a terminal connected to a multi-base station wireless LAN network based on various information related to the wireless LAN. For example, (refer to FIG. 7) the controller provides information on the strength of the wireless signal (wireless LAN signal) between the terminal 100 and the first BSS (C1) to which the terminal 100 is connected (for example, RSSI ( Received Signal Strength Indicator) value) may be received from the base station 200A. If it is determined that the signal strength is less than -60dBm, the controller may determine that steering of the corresponding terminal is required. As another example, the controller may receive information on a transmission rate of a radio signal (wireless LAN signal) between the terminal 100 and the first BSS (C1) to which the terminal 100 is connected from the base station 200A. If it is determined that the transmission speed is less than 1 Mb/s, the controller may determine that steering of the corresponding terminal is required. As described above, the controller may determine whether steering is necessary based on a single WLAN parameter or measured value, but may determine whether steering is required in combination based on two or more WLAN parameters or measured values. For example, the controller may determine that steering is necessary if the transmission speed is less than 2Mb/s and the channel utilization rate calculated as a percentage is 80% or more.

According to another embodiment, the controller may operate so that the steering can be executed at every preset period irrespective of the above-described determination criterion. That is, in the flowchart of FIG. 9, triggering may be performed so that a procedure after S120 may be performed every preset period (eg, 10 seconds) in step S110. Alternatively, the controller may be implemented such that a steering related procedure after S120 is performed in response to an external control signal or input.

When it is determined that steering is necessary, the controller may evaluate a WLAN performance between at least one Basic Service Set (BSS) included in the multi-base station WLAN network and a terminal to be steered.

Here, the WLAN performance may be evaluated based on at least one WLAN parameter (or, including values related to a WLAN link defined in a WLAN standard or used by a WLAN device manufacturer). For example, as a referenced WLAN parameter or measurement value, RSSI, number of hops, transmission rate (Throughput, transfer rate), number of terminals connected to base station/BSS (# of associated STA), spatial stream At least some of the number of (Spatial Streams) and channel utilization may be included, but embodiments of the present invention are not limited thereto. Alternatively, the WLAN parameter or measurement value referenced in the step of determining whether steering is necessary when evaluating the WLAN performance may be used as it is.

Here, each base station in the multi-base station WLAN network may measure various WLAN parameters or measured values described above, and may transmit the measured parameters and measured values to the controller.

The controller may calculate a value related to evaluation of the WLAN performance between the terminal and each BSS by referring to at least one WLAN parameter or measurement value in combination. Referring back to FIG. 7, the controller is a value related to the evaluation of the WLAN performance between the terminal 100 and the first BSS (C1) or the value related to the evaluation of the WLAN performance between the terminal 100 and the fourth BSS (C4). Can be calculated.

As a specific example, the controller has real weights a1, a2, a3, ... and a first WLAN parameter/measurement value v1, a second WLAN parameter/measurement value v2, a third WLAN parameter/measurement value v3,. For .., a wireless LAN performance evaluation value can be calculated based on an equation of a1*v1 + a2*v2 + a3*v3 + ... Alternatively, the controller may calculate a WLAN performance evaluation value through a polynomial or a function using the above-described various WLAN parameters/measurement values as variables.

The calculated WLAN performance evaluation value may be a score or point of an integer or real value. Alternatively, the calculated WLAN performance evaluation values may be stages or grades that are distinguished from each other.

According to the above, the BSS transmitting and receiving wireless signals to and from the terminal may be referred to as the parent BSS, and the score related to the WLAN performance evaluation (hereinafter, the WLAN performance evaluation score) between the parent BSS and the terminal may be referred to as a self-score. have. In addition, among the BSSs in the multi-base station WLAN network, a score related to the WLAN performance evaluation between the BSS (Basic Service Set) other than the parent BSS and the terminal may be referred to as a target score. That is, in the corresponding step, the controller may individually calculate the self score and the target score, and may select a target BSS based on the scores.

The controller may select a target BSS to be newly accessed by the terminal based on the above-described performance evaluation result value, numerical value, or score.

According to a preferred embodiment of the present invention, the controller may select a target BSS to be newly accessed by the terminal based on the self score, the target score, and a preset steering start limit value. More specifically, the controller may select a BSS representing a target score greater than the sum of the self score and the steering start limit value as the target BSS. For example, it may be assumed that the self-score calculated in the situation of FIG. 7 (the wireless LAN performance evaluation score between the first BSS and the terminal) is 50 points, and the steering start limit value is 20 points. At this time, when each target score (a WLAN performance evaluation score between the second BSS to the fourth BSS and the terminal) is 75, 55, and 46, respectively, the controller may select the second BSS as the target BSS. That is, according to an embodiment of the present invention, selection of a target BSS may be more advanced through an additional element such as a steering start limit value as well as a score according to a combination of each WLAN parameter or measurement value.

Here, the steering start limit value may be a fixed setting value, but may be changed in real time or periodically based on a surrounding environment or a wireless LAN communication environment. According to an embodiment of the present invention, the steering start limit value may be determined based on the size and type of data being transmitted/received by the terminal or scheduled to be transmitted/received with the parent BSS. For example, when a large amount of data is being transmitted between a terminal to be steered and a parent BSS, and data to be additionally transmitted is greater than or equal to a specific reference, the controller may increase the steering start limit value from the existing value. That is, when a lot of WLAN communication resources are required for the terminal, a BSS that satisfies a higher WLAN performance evaluation score may be selected as the target BSS. Conversely, when a small amount of data is being transmitted between the terminal to be steered and the parent BSS, and the additional data to be transmitted is less than a specific reference, the controller may reduce the steering start limit value from the existing value. Through this, the controller can have a higher degree of freedom in selecting the target BSS.

In addition, the controller may increase the steering start limit value when high-priority data (eg, a voice signal) is included between the terminal and the parent BSS. Conversely, the controller has priority between the terminal and the parent BSS. If low data is included, the steering start limit value may be decreased.

In addition, the controller sets at least one additional steering condition based on the size and type of data being transmitted/received or scheduled to be transmitted/received by the terminal with the parent BSS, and selects a target BSS based on whether the additional steering condition is satisfied. May be. For example, if game-related data (signals related to user manipulation input transmitted from the terminal to the BSS, video signals, audio signals, etc.) are included between the terminal and the parent BSS, in addition to the above conditions, “the number of hops is 2 It is also possible to select an additional steering condition such as “below” and select a target BSS that satisfies this.

Meanwhile, when there are two or more BSSs representing target scores greater than the sum of the self score and the steering start limit value, the controller may select the BSS representing the highest score as the target BSS. In addition, the controller may select the BSS representing the highest score as the target BSS when the additional steering condition is satisfied and there are two or more BSSs representing the target score greater than the sum of the self score and the steering start limit value.

For example, if the self-score of FIG. 7 is 50 points, the target scores (C2 to C4) are 60, 80, 75, and the steering start limit value is 20, the controller connects the terminal to the third BSS (C3). can do. As another example, if each target score is 55, 64, 46, the performance evaluation score of all BSSs does not exceed the sum of the steering start limit value and the self score, so the controller performs steering as the target BSS cannot be selected. I can't.

In addition, the controller may trigger steering so that the terminal is connected to the target Basic Service Set (BSS). 7 and 8(b), the controller may first transmit a control signal for releasing the connection (or WLAN link) between the terminal 100 and the parent BSS, the first BSS (C1), to the first BSS. Accordingly, the connection between the first BSS (C1) and the terminal 100 may be released. Then, the controller may then transmit a control signal for connection between the third BSS (C3) and the terminal 100 to the third BSS, and accordingly, a wireless LAN connection between the third BSS (C3) and the terminal 100 This may be performed, and as a result, steering of the terminal from the first BSS to the third BSS may be completed.

Meanwhile, according to FIG. 9, it is shown that the WLAN performance evaluation is performed after the step of determining whether to perform the steering, but the present invention is not limited thereto, and the controller provides a network for each terminal connected to the multi-base station WLAN network. Wireless LAN performance evaluation between each of the BSSs within the BSS may be performed at all times or periodically. In addition, the controller may determine whether to steer a specific terminal based on the result of the wireless LAN performance evaluation performed regularly/periodically. For example, in the WLAN performance evaluation performed every 10 seconds, if the WLAN performance evaluation result of a specific terminal does not satisfy a preset criterion, the steering for the corresponding terminal may be determined immediately and steps after S130 may be performed. have.

The above description of the present invention is for illustrative purposes only, and those of ordinary skill in the art to which the present invention pertains will be able to understand that other specific forms can be easily modified without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be construed that the above-described embodiments are illustrative and limiting in all respects. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as being distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims to be described later rather than the detailed description, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

100: terminal (STA)
200: base station (AP)

Claims (5)

Determining, by the controller, whether to perform steering of a terminal connected to a multi-base station wireless LAN network;
Evaluating, by the controller, a wireless LAN performance between at least one basic service set (BSS) included in a multi-base station wireless LAN network and the terminal;
Selecting, by the controller, a target BSS (Basic Service Set) to be newly accessed by the terminal based on the evaluation result; And
A step of triggering, by the controller, a steering so that the terminal is connected to the target basic service set (BSS),
The step of selecting the target BSS (Basic Service Set),
The controller,
A self-score, which is a wireless LAN performance evaluation score between the parent BSS (Basic Service Set), which is a basic service set (BSS) to which the terminal is connected, and
A target score that is a WLAN performance evaluation score between the BSS (Basic Service Set) excluding the parent BSS (Basic Service Set) among the BSS (Basic Service Set) in the multi-base station WLAN network and the WLAN performance evaluation score between the terminal and
A steering method in a multi-base station WLAN environment, comprising selecting a target Basic Service Set (BSS) based on a preset steering start limit value. The method of claim 1,
The step of evaluating the wireless LAN performance,
The controller individually calculates the self score and the target score based on at least one WLAN parameter or measurement value,
The step of selecting the target BSS (Basic Service Set),
The steering method in a multi-base station WLAN environment, characterized in that the controller selects a basic service set (BSS) representing a target score greater than the sum of the self-score and the steering start limit value as a target basic service set (BSS). . The method of claim 2,
The steering start limit value is,
The steering method in a multi-base station WLAN environment, wherein the terminal is determined based on the size and type of data being transmitted/received or scheduled to be transmitted/received with a parent BSS (Basic Service Set). The method of claim 2,
The step of selecting the target BSS (Basic Service Set),
The controller sets at least one additional steering condition based on the size and type of data that the terminal is transmitting/receiving with a parent BSS (Basic Service Set) or scheduled to be transmitted/received, and the target based on whether the additional steering condition is satisfied. A steering method in a multi-base station WLAN environment, characterized in that BSS (Basic Service Set) is selected. The method of claim 2,
The step of selecting the target BSS (Basic Service Set),
When the controller has more than one BSS (Basic Service Set) representing a target score greater than the sum of the self score and the steering start limit value, the BSS (Basic Service Set) representing the highest score is set as the target BSS (Basic Service Set). Steering method in a multi-base station wireless LAN environment, characterized in that the selection.

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