KR20220135094A - Method of roaming between access points and terminal for providing roaming - Google Patents

Abstract

Disclosed is a roaming method between access points according to the movement of a terminal. The roaming method comprises the following steps of: detecting, by the terminal, a signal level between the terminal and a first access point currently connected for wireless communication; and initiating, by the terminal, a roaming process in response to detecting that the signal level is below a predetermined level. The roaming process comprises the following steps of: determining whether the terminal is on a call; transmitting a probe request frame at a first scan time in response to detecting that the terminal is not busy, wherein the first scan time is a scan time for each channel included in a frequency band of wireless communication for roaming; transmitting the probe request frame at a second scan time in response to detecting that the terminal is on a call, wherein the second scan time is a scan time for each channel included in a frequency band of wireless communication for roaming, and the second scan time is shorter than the first scan time; receiving, by the terminal, a probe response frame from a second access point; and accessing, by the terminal, the second access point.

Description

Method of roaming between access points and terminals providing roaming

The present disclosure relates to a communication field, and more particularly, to a roaming method between access points and a terminal providing roaming.

The communication system may include a client (Station, "terminal") and an access point (Access Point, "AP"). Wi-Fi (Wireless Fidelity, "Wi-Fi") technology is based on the IEEE 802.11 protocol family, and is a general term for a technology that supports short-range wireless network communication in a communication system. The terminal and the AP perform communication using a wireless interface, that is, through wireless transmission. The AP connects the terminal to the local area network of the Internet so that the terminal can access the Internet. Since the AP supports local area network communication in a certain area, when the terminal moves, the terminal must connect to the AP supporting the corresponding area. For example, the terminal may change the AP accessing from AP1 to AP2 according to movement. The operation of the terminal changing the connection from AP1 to AP2 may be referred to as roaming. When the terminal moves from AP1 to AP2, the terminal sends a probe request to AP2, receives a probe response from AP2, and connects to AP2 using information in the probe response. When the terminal sends a probe request to find an AP, the load on the CPU of the terminal increases, which may affect call quality. In addition, when the terminal is moving, the wireless signal with the existing AP changes and the roaming processing time increases, the change in the wireless signal increases, which may affect call quality. Therefore, fast roaming processing is required to improve call quality.

Korean Patent Registration No. 10-2169437 Korean Patent Registration No. 10-1796589 Korean Patent Registration No. 10-2010362 Korean Patent Publication No. 10-2017-0071592 Korean Patent Publication No. 10-2014-0112558

The present disclosure provides a method for quickly finding and connecting to AP2 in a roaming process in which a terminal changes access from AP1 to AP2. In addition, the present disclosure provides a terminal in which the terminal quickly performs roaming processing for changing a connection from AP1 to AP2.

According to one aspect of the present disclosure, a roaming method between access points according to movement of a terminal is disclosed. The roaming method includes: detecting, by the terminal, a signal level between the terminal and a first access point currently connected for wireless communication; and initiating, by the terminal, a roaming process in response to detecting the signal level being below a predetermined level. The roaming process may include: determining whether the terminal is in a call; transmitting a probe request frame at a first scan time in response to determining that the terminal is not in a call, wherein the first scan time is a scan time for each channel included in a frequency band of wireless communication for roaming; Transmitting the probe request frame at a second scan time in response to determining that the terminal is on a call - The second scan time is a scan time for each channel included in a frequency band of wireless communication for the roaming, and the second scan time is shorter than the first scan time; receiving, by the terminal, a probe response frame from a second access point; and connecting the terminal to the second access point.

In an embodiment, the first scan time may be 40 ms or more and 60 ms or less, and the second scan time may be 10 ms or more and 20 ms or less.

In an embodiment, the frequency band includes a first frequency band and a second frequency band, and the number of channels included in the first frequency band is less than the number of channels included in the second frequency band. The transmitting of the probe request frame at a second scan time in response to determining that the terminal is in a call may include: determining whether the frequency band includes the second frequency band; and in response to determining that the frequency band includes the second frequency band, transmitting, by the terminal, the probe request frame to each channel included in the second frequency band at the second scan time. can

In an embodiment, the wireless communication may be Wi-Fi, the first frequency band may be a 2.4 GHz band, and the second frequency band may be a 5 GHz band.

In an embodiment, determining whether the frequency band includes the second frequency band may include determining based on a setting of the terminal.

In an embodiment, the determining whether the frequency band includes the second frequency band includes determining based on a frequency band used between the terminal and a first access point currently connected for wireless communication may include

According to one aspect of the present disclosure, a roaming method between access points according to movement of a terminal is disclosed. The roaming method includes: detecting, by the terminal, a signal level between the terminal and a first access point currently connected for wireless communication; and starting, by the terminal, a roaming process in response to detecting that the signal level is below a predetermined level. The roaming process includes: determining whether the terminal is in a call; determining, by the terminal, a frequency band for roaming - The frequency band includes a first frequency band and a second frequency band, and the number of channels included in the first frequency band is the number of channels included in the second frequency band less than the number of -; transmitting a probe request frame at a first scan time in response to determining that the terminal is not in a call, wherein the first scan time is a scan time for each channel included in the first frequency band; Transmitting the probe request frame at a second scan time in response to determining that the terminal is on a call and determining that the frequency band for roaming includes the second frequency band - the second scan time is a scan time for each channel included in the second frequency band, and the second scan time is shorter than the first scan time; receiving, by the terminal, a probe response frame from a second access point; and connecting the terminal to the second access point.

In an embodiment, the method may further include transmitting the probe request frame at the first scan time in response to determining that the frequency band for roaming is only the first frequency band.

In an embodiment, the first scan time may be 40 ms or more and 60 ms or less, and the second scan time may be 10 ms or more and 20 ms or less.

In an embodiment, the wireless communication may be Wi-Fi, the first frequency band may be a 2.4 GHz band, and the second frequency band may be a 5 GHz band.

In an embodiment, the step of determining, by the terminal, a frequency band for roaming may include determining based on a setting of the terminal.

In an embodiment, the step of determining, by the terminal, a frequency band for roaming may include determining based on a frequency band used between the terminal and a first access point currently connected for wireless communication. have.

In one embodiment, in response to determining that the terminal is in a call, the terminal may perform the step of determining a frequency band for roaming.

According to one aspect of the present disclosure, a terminal includes a processor; a communication module configured to provide roaming between the first access point and the second access point; and a memory configured to store instructions that, when executed by the processor, cause the processor and the communication module to perform the method for roaming. The method for roaming includes: detecting, by the terminal, a signal level between the terminal and the first access point connected for the wireless communication; and determining whether the terminal is in a call or not in response to detecting that the signal level is below a predetermined level. transmitting a probe request frame at a first scan time in response to determining that the terminal is not in a call, wherein the first scan time is a scan time for each channel included in a frequency band of wireless communication for roaming; Transmitting the probe request frame at a second scan time in response to determining that the terminal is on a call - The second scan time is a scan time for each channel included in a frequency band of wireless communication for the roaming, and the second scan time is shorter than the first scan time; receiving, by the terminal, a probe response frame from a second access point; and connecting the terminal to the second access point.

In an embodiment, the roaming may be performed according to a Wi-Fi standard, the first scan time may be 40 ms or more and 60 ms or less, and the second scan time may be 10 ms or more and 20 ms or less.

According to one aspect of the present disclosure, a terminal includes a processor; a communication module configured to provide roaming between the first access point and the second access point; and a memory configured to store instructions that, when executed by the processor, cause the processor and the communication module to perform the method for roaming. A method for roaming includes: detecting, by the terminal, a signal level between the terminal and a first access point currently connected for wireless communication; and starting, by the terminal, a roaming process in response to detecting that the signal level is below a predetermined level. The roaming process includes: determining whether the terminal is in a call; determining, by the terminal, a frequency band for roaming - The frequency band includes a first frequency band and a second frequency band, and the number of channels included in the first frequency band is the number of channels included in the second frequency band less than the number of -; transmitting a probe request frame at a first scan time in response to determining that the terminal is not in a call, wherein the first scan time is a scan time for each channel included in the first frequency band; Transmitting the probe request frame at a second scan time in response to determining that the terminal is on a call and determining that the frequency band for roaming includes the second frequency band - the second scan time is a scan time for each channel included in the second frequency band, and the second scan time is shorter than the first scan time; receiving, by the terminal, a probe response frame from a second access point; and connecting the terminal to the second access point.

In an embodiment, the wireless communication is Wi-Fi, the first frequency band is a 2.4 GHz band and the second frequency band is a 5 GHz band, the first scan time is 40 ms or more and 60 ms or less, and the second The scan time is 10ms or more and 20ms or less.

In one embodiment, the memory stores setting information on which frequency band to access with the second access point, and the terminal is configured to determine the frequency band for roaming based on the setting information can be

When a connection between an existing AP and another AP is required due to movement during a call, roaming can be performed quickly to provide stable voice quality.

1A and 1B are conceptual diagrams illustrating an embodiment in which a terminal is assigned an IP in a network.
2 is a block diagram of a terminal according to an embodiment of the present disclosure.
3 is a conceptual diagram of a roaming scan according to an embodiment of the present disclosure.
4 is a flowchart of a roaming process according to an embodiment of the present disclosure;
5 is a flowchart of a roaming process according to an embodiment of the present disclosure.
6 is a flowchart of a roaming process according to an embodiment of the present disclosure.
7 is a flowchart of a roaming process according to an embodiment of the present disclosure.

Hereinafter, the present disclosure will be described in detail with reference to the drawings. In describing the present disclosure, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present disclosure, a detailed description thereof will be omitted. In addition, the following examples may be modified in various other forms, and the scope of the technical spirit of the present disclosure is not limited to the following examples. Rather, these embodiments are provided to more fully and complete the present disclosure, and to fully convey the technical spirit of the present disclosure to those skilled in the art.

Documents presented as prior art in this disclosure are hereby incorporated by reference in their entirety.

It is to be understood that the techniques described in the present disclosure are not intended to be limited to specific embodiments, and include various modifications, equivalents, and/or alternatives of the embodiments of the present disclosure.

In connection with the description of the drawings, like reference numerals may be used for like components.

In the present disclosure, expressions such as “have,” “may have,” “include,” or “may include” indicate the presence of a corresponding characteristic (eg, a numerical value, function, operation, or component such as a part). and does not exclude the presence of additional features. In this disclosure, expressions such as “A or B,” “at least one of A and/and B,” or “one or more of A or/and B” may include all possible combinations of the items listed together. . For example, "A or B," "at least one of A and B," or "at least one of A or B" means (1) includes at least one A, (2) includes at least one B; Or (3) it may refer to all cases including both at least one A and at least one B.

As used in the present disclosure, expressions such as “first,” “second,” “first,” or “second,” may modify various elements, regardless of order and/or importance, and refer to one element. It is used only to distinguish it from other components, and does not limit the components.

A component (eg, a first component) is "coupled with/to (operatively or communicatively)" to another component (eg, a second component) When referring to "connected to", it should be understood that the certain element may be directly connected to the other element or may be connected through another element (eg, a third element). On the other hand, when it is said that a component (eg, a first component) is "directly connected" or "directly connected" to another component (eg, a second component), the component and the It may be understood that other components (eg, a third component) do not exist between other components.

The expression "configured to (or configured to)" as used in this disclosure depends on the context, for example, "suitable for," "having the capacity to" ," "designed to," "adapted to," "made to," or "capable of." The term “configured (or configured to)” may not necessarily mean only “specifically designed to” hardware. Instead, in some circumstances, the expression “a device configured to” may mean that the device is “capable of” with other devices or parts. For example, the phrase "a processor configured (or configured to perform) A, B, and C," a module configured (or configured to perform) A, B, and C," refers to a dedicated processor (eg, : embedded processor) or a generic-purpose processor (eg, CPU or application processor) capable of performing corresponding operations by executing one or more software programs stored in a memory device.

1A and 1B are conceptual diagrams illustrating an embodiment in which a terminal 200 is assigned an IP in a network. The terminal 200 is capable of wireless communication with a smartphone, laptop, etc., including one or more communication systems implemented to support 3G, 4G and/or LTE cellular communication technologies, as well as several radio access technologies such as Bluetooth™ and WiFi. It is a device.

Referring to FIG. 1A , in a network address translation (NAT) mode, an AP performs an agent function between a public network and a local network. When one public IP address is assigned to a plurality of APs, each of the APs provides a private IP to the terminal 200 . Referring to FIG. 1B , the DHCP server allocates an IP to each AP, and each AP provides the assigned IP to the terminal 200 . The AP may be a workstation that functions as a Basic Service Set (“BSS”) for infrastructure management and allows a terminal to access a network. Currently, the terminal can be manufactured to use the Wi-Fi service using the 2.4 GHz band and the 5 GHz band. Each band is divided into a plurality of channels, and the terminal is connected to the AP through one of the channels. Each country uses different channels depending on the band. Currently, Korea divides the 2.4GHz band into 13 channels and uses the 5GHz band by dividing it into 23 channels.

The protocol layer connection between the AP and the terminal 200 may be a Transmission Control Protocol (“TCP”)/Internet Protocol (“IP”) connection.

The encryption method of the wireless network may be a Wi-Fi protected access (Wireless Fidelity Protected Access, "WAP") or WAP2. In addition, the method for handover between access points in the embodiment of the present invention is a scenario in which another encryption scheme is used for encryption of a wireless network or the wireless network is not encrypted, for example, Wired Equivalent Privacy ("WEP"). ) method or an open method may be applied to a scenario in which encryption of a wireless network is used.

In order to access an AP in a Wi-Fi hotspot network, it is necessary to check the list of APs through the SCAN List and check whether the AP is connectable through the list of APs. A connection setting operation and the like may be performed.

1A and 1B , when the terminal 200 moves from the area of AP1 to the area of AP2, the strength of a wireless signal connected to AP1 will drop below a certain level. The terminal 200 operates to find AP2, and if the signal level of AP2 is higher than the signal level of AP1 or higher than a certain signal level, the terminal 200 disconnects from AP1 and accesses AP2 to use Wi-Fi. operate so that

2 is a block diagram of a terminal 200 according to an embodiment of the present disclosure.

The terminal 200 includes a processor 210 , a memory 220 , and a communication module 230 .

Processor 210 may be an integrated circuit, a programmable logic device, a logic device formed using one or more semiconductors, and other implementations of silicon and/or hardware, such as a processor and memory system implemented as a system-on-chip (SoC). may include components of Terminal 200 may further include any type of system bus or other data and command transfer system that couples the various components within terminal 200 . The system bus may include control and data lines as well as any one or combination of different bus structures and architectures.

Memory 220 can be accessed by a computing device and is computer readable, such as data storage devices that provide persistent storage of data and executable instructions (eg, software applications, programs, functions, etc.). It is a storage medium. Examples of memory 220 include volatile and non-volatile memory, fixed and removable media devices, and any suitable memory device or electronic data store that maintains data for computing device access. Memory 220 may include various implementations of random access memory (RAM), read-only memory (ROM), flash memory, and other types of storage media in various memory device configurations. . Memory 220 is configured to store executable software instructions (eg, computer executable instructions) executable with processor 210 , or a software application such as may be implemented as a module. In one embodiment, memory 220 may include Wi-Fi control commands 222 and software application commands 224 . The processor 210 may control the connection between the terminal 200 and the AP by the Wi-Fi control command 222 .

The memory 220 stores the operating system of the terminal 200, and programs and data related to the power consumption management function control operation according to the Wi-Fi use of the terminal 200, the search cycle setting, and the communication module 230 operation operation. Programs and data can be stored continuously or temporarily. The memory 220 may store setting information. In the present disclosure, the setting information includes information on an automatic or manual search method for a scan period, information on a scan period set by a user, information for guidance for each search period, frequency band information to be used, and frequency bands before/after roaming. may include information about

The communication module 230 supports Internet Protocol (IP)-based wireless communication (eg, communication for a Wi-Fi service). The communication module 230 processes signaling transmission/reception for a neighboring AP search in a search cycle set according to the control of the Wi-Fi control command 222 . For example, the communication module 230 is a Wi-Fi chip kernel processor, and implements a Wi-iFi-related operation function, for example, congestion control, carrier aggregation, frame filtering, key control, and frame reception/transmission management. can be in charge, etc. It may be understood that the processor 210 and the communication module 230 may be integrated into one chip. In addition, embodiments of the present disclosure may be performed by the processor 210 or the communication module 230 .

3 is a conceptual diagram of a roaming scan according to an embodiment of the present disclosure.

Referring to FIG. 3 , when the terminal 200 moves and the distance from the existing AP increases and the signal level falls below a certain strength, the terminal 200 may perform a roaming scan. The roaming scan may be performed to find an AP having a signal level above a certain level among APs existing around the terminal 200 . The roaming scan may be used to determine the existence and operating characteristics of an unused network (AP) in a wireless network. The predetermined signal level may be set differently according to the detection condition of the call disconnection and the reception level. That is, the disconnection of the call may be determined based on the lowest signal level of -100 dbm, and the reception level may be determined as good, good, or weak signal level based on thresholds -68 dbm and -75 dbm. If the signal level is weak, a roaming scan can be initiated.

Roaming scans can generate a list of alternative networks that can be used in case the signal strength of the currently connected network is degraded. The roaming scan may be performed at regular intervals. A roaming scan may be performed by transmitting/receiving probe request and probe response frames that may be transmitted on wireless channels conforming to the IEEE 802.11 standard.

In the scanning process, the terminal 200 transmits a probe request frame (also referred to as a signal or message), and the AP receiving the probe request frame transmits a probe response frame to the terminal 200 . The terminal 200 may receive the probe response frame and obtain information about the neighboring APs therefrom. The probe response frame includes an SSID, a Basic Service Set Identifier (“BSSID”), an operating channel, a bandwidth of the AP, a Received Signal Strength Indication (“RSSI”) corresponding to the AP, and other information. may include at least one of

The scan may be performed for each predetermined frequency band (or a channel of the frequency band). For example, when Wi-Fi is a 2.4 GHz frequency band, a frequency band of about 2,400 Mhz to 2,483.5 MHz is used, and the band may be divided into a plurality of, for example, 13 channels. The scan may be performed using one channel at a time, for example, sequentially or randomly selected from each of the 13 channels. That is, the terminal 200 may transmit a probe request frame and receive a probe response frame using one channel for a predetermined time (eg, a channel scan time). By repeating the scan for each channel as many as the number of channels (eg, 13 times), a Wi-Fi scan of the 2.5 GHz band is performed. The number of channels and the bandwidth of the channels may be determined as a standard.

When Wi-Fi is a 5 GHz frequency band, a frequency band of about 5,725 Mhz to 5,875 MHz is used, and the band may be divided into a plurality of, for example, 23 channels. The scan may be performed, for example, using one channel at a time by sequentially or arbitrarily selecting each of the 23 channels. That is, the terminal 200 may transmit a probe request frame and receive a probe response frame using one channel for a predetermined time (eg, a channel scan time). This scan for each channel is repeated as many as the number of channels (eg, 23 times) to perform a Wi-Fi scan of the 5 GHz band. The number of channels and the bandwidth of the channels may be determined as a standard.

In one embodiment, the channel scan time may be predetermined. When the terminal 200 does not receive the probe response frame at the predetermined channel scan time, the terminal 200 may transmit the probe request frame through the next channel.

In an embodiment, a list of APs that have transmitted the probe response frame is made by receiving the probe response frame through a scan for each channel. Select the AP with the strongest signal level from the list of APs and try to connect. When an AP is selected, the terminal 200 sends an authentication request signal to the selected AP, and the AP receiving the authentication request signal sends an approval or rejection signal to the terminal 200 . Upon receiving the approval signal from the AP, the terminal 200 transmits a re-association request signal and receives a response. If a separate password is required, the terminal 200 and the AP perform key exchange. Accordingly, the terminal 200 performs a new connection with the new AP.

In an embodiment, Wi-Fi of the 2.4 GHz band and Wi-Fi of the 5 GHz band may be used together. For example, if the signal strength decreases during the initial service through the 5 GHz frequency band, roam to the 2.4 GHz frequency band, and the signal strength of the 2.4 GHz frequency band decreases or an access point in the 5 GHz frequency band to be accessed preferentially in the vicinity In the presence of , it can automatically return to the 5GHz frequency band again. The present invention is not limited thereto, and roaming from the 2.4 GHz frequency band to the 2.4 GHz frequency band, from the 5 GHz frequency band to the 5 GHz frequency band, or from the 2.4 GHz frequency band to the 5 GHz frequency band is also applicable.

Although the present disclosure specifically describes the 5 GHz frequency band and the 2.4 GHz frequency band with respect to the dual band of Wi-Fi, the present disclosure is not limited thereto and may include a new band capable of wireless Internet if it exists. To include this, the dual band may be referred to as a first frequency band and a second frequency band.

4 is a flowchart of a roaming process according to an embodiment of the present disclosure; The roaming process may be stored in the memory 220 or a memory (not shown) of the communication module 230 .

Referring to FIG. 4 , the terminal 200 detects a signal level ( S405 ). In response to detecting that the signal level is below a predetermined threshold, the terminal 200 may trigger a roaming process. The terminal 200 determines whether the current user is in a call using the terminal 200 (S410). In an embodiment, the terminal 200 may determine whether the terminal 200 is in a call or not through a Real-time Transport Protocol (“RTP”).

In response to determining that the terminal 200 is not in a call, the terminal 200 transmits a probe request frame (S415). The terminal 200 may transmit the probe request frame using any one channel (eg, the first channel) of the communication frequency band. In an embodiment, the probe request frame may be transmitted a plurality of times during the first scan time. The terminal 200 may transmit the probe request frame a plurality of times before receiving the probe response frame during the first scan time. In an embodiment, the first scan time may be a preset value. In an embodiment, the terminal 200 may request a plurality of probe request frames per one channel and transmit the plurality of probe request frames through all channels.

The terminal 200 determines whether a probe response frame is received from the AP within the first scan time (S420). If it is determined that the probe response frame is not received within the first scan time, the probe request frame is transmitted again using a different channel (eg, a second channel) different from the first channel. The terminal 200 may repeat steps S415 and S420 until the probe response frame is received within the first scan time.

In response to determining that the terminal 200 has received the probe response frame within the first scan time, the terminal 200 determines whether a signal level (eg, RSSI) recorded in the probe response frame is equal to or greater than a set value ( S425). In response to determining that the signal level is smaller than the set value, the terminal 200 transmits a probe request frame through another channel. The terminal 200 may repeat steps S415, S420, and S425 until the probe response frame is received within the first scan time. In response to determining that the signal level is greater than or equal to the set value, the terminal 200 attempts to access the AP that has transmitted the probe request frame recording the signal level equal to or greater than the set value (S430).

In response to determining that the terminal 200 is in a call, the terminal 200 transmits a probe request frame (S435). The terminal 200 may transmit the probe request frame using any one channel (eg, the first channel) of the communication frequency band. In an embodiment, the probe request frame may be transmitted a plurality of times during the second scan time. The terminal 200 may transmit the probe request frame a plurality of times before receiving the probe response frame during the second scan time. In an embodiment, the second scan time may be a preset value.

The second scan time may be shorter than the first scan time. For example, the first scan time may be about 40 ms, 50 ms, 60 ms, or 40 ms to 60 ms and the second scan time may be about 10 ms, 20 ms, or 10 ms to 20 ms.

The terminal 200 determines whether a probe response frame is received from the AP within the second scan time (S440). If it is determined that the probe response frame is not received within the second scan time, the probe request frame is transmitted again using another channel (eg, a second channel) different from the second channel. The terminal 200 may repeat steps S435 and S440 until the probe response frame is received within the second scan time.

In response to determining that the terminal 200 has received the probe response frame within the second scan time, the terminal 200 determines whether a signal level (eg, RSSI) recorded in the probe response frame is equal to or greater than a set value ( S445). In response to determining that the signal level is smaller than the set value, the terminal 200 transmits a probe request frame through another channel. The terminal 200 may repeat steps S435, S440, and S445 until the probe response frame is received within the second scan time. In response to determining that the signal level is greater than or equal to the set value, the terminal 200 attempts to access the AP that has transmitted the probe request frame recording the signal level equal to or greater than the set value (S450).

In the above, steps S415 and S435 have been described as being performed after step S410, but one channel is configured for a different scan time (for example, any one period of the first scan time or the second scan time) depending on whether a call is in progress. Any configuration or method for receiving a probe response frame by transmitting a probe request frame by repeating scanning is included in the present disclosure. For example, when the signal level is equal to or less than a predetermined level, a roaming process is triggered, and a scan time from transmitting a probe request frame to receiving a probe response frame may be different depending on whether a call is in progress. Alternatively, the roaming process may be triggered and a probe request frame may be transmitted by setting a scan time.

When not on a call, a longer scan time does not affect call quality, but when on a call, the scan time may affect call quality. Therefore, when a call is in progress, the call quality can be secured by roaming quickly by shortening the scan time compared to when not in a call.

5 is a flowchart of a roaming process according to an embodiment of the present disclosure.

5, the terminal 200 detects a signal level (S505). In response to detecting that the signal level is below a predetermined threshold, the terminal 200 may trigger a roaming process.

The terminal 200 determines the frequency band used by the terminal 200 (S510). Determination of the frequency band may be performed in real time. Alternatively, the frequency band is temporarily stored in the memory 220 when the terminal 200 is connected to the AP and can be determined using the stored frequency band. In addition, a frequency band that is a target of roaming is preset in the memory 220 and can be used.

In one embodiment, a setting for a frequency band is stored in the memory 220 . For example, when using Wi-Fi dual bands of 2.4 GHz and 5 GHz, a frequency band used by a roaming process may be set. If the roaming process is performed while using 2.4GHz, it may be set to find an AP in the 2.4GHz band. If the roaming process is performed while using 5GHz, it may be set to find an AP in the 5GHz band. When a roaming process is performed while using 2.4GHz, it may be set to search for an AP in either band of 2.4GHz or 5GHz. When a roaming process is performed while using 5GHz, it may be set to search for an AP in either band of 2.4GHz or 5GHz. Determining the frequency in step S510 may include determining which frequency band to use. For example, in step S510 , the terminal 200 may determine which frequency to use for roaming according to a setting stored in the memory 220 .

In an embodiment, the terminal 200 may determine a frequency to be used by roaming according to a currently used frequency band. For example, when Wi-Fi is used as the first frequency band, it may be determined that the frequency band to be used by roaming is the first frequency band.

In response to determining that the terminal 200 is using the first frequency band, the terminal 200 transmits a probe request frame (S515). The terminal 200 may transmit the probe request frame at the first scan time using any one channel (eg, the first channel) of the communication frequency band. In an embodiment, the first scan time may be a preset value.

In an embodiment, when the roaming process is triggered while using the first frequency band, the roaming process may be performed to use only the first frequency band. Alternatively, when the roaming process is triggered while using the first frequency band, the roaming process may be performed to use only the second frequency band. Alternatively, when the roaming process is triggered while using the first frequency, the roaming process may be performed to use the first or second frequency band.

In an embodiment, the first frequency band may be a 2.4 GHz frequency band. The 2.4 GHz frequency band may be divided into 13 channels. The terminal 200 determines whether a probe response frame is received from the AP within the first scan time (S420). If it is determined that the probe response frame is not received within the first scan time, the probe request frame is transmitted again using a different channel (eg, a second channel) different from the first channel. The terminal 200 may repeat steps S515 and S520 until the probe response frame is received within the first scan time. That is, the terminal 200 may repeat steps S515 and S520 up to 13 times.

In response to determining that the terminal 200 has received the probe response frame within the first scan time, the terminal 200 determines whether a signal level (eg, RSSI) recorded in the probe response frame is equal to or greater than a set value ( S525). In response to determining that the signal level is smaller than the set value, the terminal 200 transmits a probe request frame through another channel. The terminal 200 may repeat steps S515, S520, and S525 until the probe response frame is received within the first scan time. In response to determining that the signal level is greater than or equal to the set value, the terminal 200 attempts to access the AP that has transmitted the probe request frame recording the signal level equal to or greater than the set value (S530).

In an embodiment, roaming may be performed from the 2.4 GHz band to the 2.4 GHz band. In this case, the 5 GHz band may not be subject to roaming. Accordingly, the number of channels to be scanned by the terminal 200 may be 13. In this case, the scan time may be about 40 ms, 50 ms, 60 ms, or 40 ms to 60 ms. Since the number of channels to be scanned is smaller than the number of channels (eg, 23) of the 5 GHz band, the scan time may be set longer than the time to scan the channels of the 5 GHz band.

In response to determining that the terminal 200 is using the second frequency band, the terminal 200 transmits a probe request frame (S535). The terminal 200 may transmit the probe request frame at the second scan time using any one channel (eg, the first channel) of the communication frequency band. In an embodiment, the second scan time may be a preset value.

In an embodiment, when the roaming process is triggered while using the second frequency band, the roaming process may be performed to use only the second frequency band. Alternatively, when the roaming process is triggered while using the second frequency band, the roaming process may be performed to use only the first frequency band. Alternatively, when the roaming process is triggered while using the second frequency band, the roaming process may be performed to use the first or second frequency band.

In an embodiment, the second frequency may be a 5 GHz frequency band. The 5 GHz frequency band may be divided into 23 channels. The terminal 200 determines whether a probe response frame is received from the AP within the second scan time (S540). If it is determined that the probe response frame is not received within the second scan time, the probe request frame is transmitted again using another channel (eg, a second channel) different from the first channel. The terminal 200 may repeat steps S535 and S540 until the probe response frame is received within the second scan time. That is, the terminal 200 may repeat steps S535 and S540 up to 23 times.

In response to determining that the terminal 200 has received the probe response frame within the second scan time, the terminal 200 determines whether a signal level (eg, RSSI) recorded in the probe response frame is equal to or greater than a set value ( S545). In response to determining that the signal level is smaller than the set value, the terminal 200 transmits a probe request frame through another channel. The terminal 200 may repeat steps S535, S540, and S545 until the probe response frame is received within the second scan time. In response to determining that the signal level is equal to or greater than the set value, the terminal 200 attempts to connect with the AP that has transmitted the probe request frame recording the signal level equal to or greater than the set value (S550).

In an embodiment, roaming may be performed from the 5 GHz band to the 5 GHz band. In this case, the 2.4 GHz band may not be subject to roaming. Therefore, the number of channels to be scanned by the terminal 200 may be 23. In this case, the scan time may be about 10 ms, 20 ms, or 10 ms to 20 ms. Since the number of channels to be scanned is larger than the number of channels in the 2.4GHz band (for example, 13), the scan time is set shorter than the time to scan the channels in the 2.4GHz band, and the total scan time (number of channels) × scan time) can be adjusted. That is, if the scan time is made equal to the channel scan time of the 2.4 GHz band, the roaming time is long because the total scan time is relatively large compared to the total scan time of the 2.4 GHz band, and the terminal 200 is in a call state. This may adversely affect call quality. Therefore, when roaming from the 5 GHz band to the 5 GHz band, the scan time per channel is reduced, so that when roaming is required in a call state, the call quality can be improved by roaming quickly.

The present disclosure may include a configuration or method of differently configuring or adjusting a scan time of a channel according to a frequency band in consideration of that a total scan time is different when the frequency band has a different number of channels.

In the above-described embodiment, an example of roaming from a first frequency band (eg, 2.4 GHz) to a first frequency band or roaming from a second frequency band (eg, 5 GHz) to a second frequency band will be described. did. The present disclosure may be applied to a case of roaming from a first frequency to any one of the first and second frequencies, or roaming from a second frequency band to any one of the first and second frequency bands. In an embodiment, roaming may be performed in any one of a band including a 5 GHz band, for example, 2.4 GHz and 5 GHz. In this case, since the number of channels is 36 in total, the scan time for each channel may be about 10 ms, 20 ms, or 10 ms to 20 ms. Alternatively, when scanning the 5 GHz band, the scan time per channel may be about 10 ms, 20 ms, or 10 ms to 20 ms, and when scanning the 2.4 GHz band, the scan time per channel may be about 40 ms, 50 ms, 60 ms, or 40 ms to 60 ms.

6 is a flowchart of a roaming process according to an embodiment of the present disclosure.

Referring to FIG. 6 , the terminal 200 detects a signal level ( S605 ). In response to detecting that the signal level is below a predetermined threshold, the terminal 200 may trigger a roaming process.

The terminal 200 determines whether the current user is in a call using the terminal 200 (S610). In an embodiment, the terminal 200 may determine whether the terminal 200 is in a call or not through a Real-time Transport Protocol (“RTP”).

In response to determining that the terminal 200 is not in a call, an AP is searched for the first scan time and an access is attempted (S615). Since the method of searching for and accessing the AP using the first scan time has been described in detail with reference to FIGS. 4 and 5 , a detailed description thereof will be omitted.

In response to determining that the terminal 200 is in a call, the terminal 200 checks the settings (S620). In an embodiment, a frequency band to be roamed is preset in the memory 220 and can be checked. A frequency setting may be stored in the memory 220 . For example, when using Wi-Fi dual bands of 2.4 GHz and 5 GHz, a frequency band used by a roaming process may be set. When the roaming process is performed while using the 2.4 GHz band, it may be set to find only the AP of the 2.4 GHz band. When the roaming process is performed while using the 5GHz band, it may be set to find only the AP of the 5GHz band. When the roaming process is performed while using the 2.4 GHz band, it may be set to search for an AP in either band of 2.4 GHz or 5 GHz. When the roaming process is performed while using the 5 GHz band, it may be set to search for an AP in either band of 2.4 GHz or 5 GHz.

The setting is checked to determine which frequency band to use in the roaming process (S625). For example, in step S625 , the terminal 200 may determine which frequency band is the frequency band to be used by roaming according to a setting stored in the memory 220 . The number of channels in the first frequency band is less than the number of channels in the second frequency band.

In response to determining that the first frequency band will be used by the frequency determination, the terminal 200 searches for an AP with the first scan time and attempts to access (S615).

In response to determining that the second frequency band will be used by the frequency determination, the terminal 200 searches for an AP with the second scan time and attempts to access (S630). In one embodiment, the second scan time is shorter than the first scan time. In another embodiment, in response to determining that the terminal 200 will search both the second frequency band and the first frequency band by frequency band determination, the terminal 200 searches for an AP with the second scan time and establishes a connection you can try

7 is a flowchart of a roaming process according to an embodiment of the present disclosure.

Referring to FIG. 7 , the terminal 200 detects a signal level ( S705 ). In response to detecting that the signal level is below a predetermined threshold, the terminal 200 may trigger a roaming process.

The terminal 200 confirms the setting (S710). In an embodiment, a frequency to be roamed is preset in the memory 220 and can be checked. A frequency setting may be stored in the memory 220 . For example, when using Wi-Fi dual bands of 2.4 GHz and 5 GHz, a frequency band used by a roaming process may be set. When performing a roaming process while using 2.4GHz, it may be set to find only an AP in the 2.4GHz band. If the roaming process is performed while using 5GHz, it may be set to find only APs in the 5GHz band. When a roaming process is performed while using 2.4GHz, it may be set to search for an AP in either band of 2.4GHz or 5GHz. When a roaming process is performed while using 5GHz, it may be set to search for an AP in either band of 2.4GHz or 5GHz.

The setting is checked to determine which frequency band to use in the roaming process (S715). For example, in step S625 , the terminal 200 may determine which frequency band is the frequency band to be used by roaming according to a setting stored in the memory 220 . The number of channels in the first frequency band is less than the number of channels in the second frequency band.

In response to determining that the terminal 200 will roam to use the first frequency band, it searches for an AP with the first scan time and attempts to access (S720). Since the method of searching for and accessing the AP using the first scan time has been described in detail with reference to FIGS. 4 and 5 , a detailed description thereof will be omitted.

In response to determining that the terminal 200 is to roam to use the second frequency band, the terminal 200 determines whether the user is currently in a call using the terminal 200 (S725). In another embodiment, in response to determining that the terminal 200 will search both the second frequency band and the first frequency band by frequency band determination, the terminal 200 searches for an AP with the second scan time and establishes a connection you can try

In response to determining that the terminal 200 is not in a call, an AP is searched for the first scan time and an access attempt is made (S720).

In response to determining that the terminal 200 is in a call, the terminal 200 may search for an AP at the second scan time and attempt to access (S730).

According to the present disclosure, when roaming is required in a frequency band with a large number of channels during a call, call quality can be improved by performing an AP search for a relatively short scan time so that roaming is performed faster.

In an embodiment, the Wi-Fi may include a Wi-Fi communication network capable of supporting Hotspot 2.0 in which a network is automatically switched from a mobile communication network to a Wi-Fi communication network. And, the external device that the terminal connects to through the Wi-Fi network is an AP (Access Pont), which is an AP that supports Hotspot 2.0 connected to an information server, or an AP that does not support Hotspot 2.0 that is not connected to an information server. may include An AP not supporting Hotspot 2.0 that is not connected to the information server is a general AP, and may indicate an AP that is connected only when selected by a user or is automatically connected when connection information is previously stored.

The apparatus and method described above may be implemented as a hardware component, a software component, and/or a combination of the hardware component and the software component. For example, devices and components described in the embodiments may include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable array (FPA), It may be implemented using one or more general purpose or special purpose computers, such as a programmable logic unit (PLU), microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For convenience of understanding, although one processing device is sometimes described as being used, one of ordinary skill in the art will recognize that the processing device includes a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that may include For example, the processing device may include a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as parallel processors.

The software may comprise a computer program, code, instructions, or a combination of one or more thereof, which configures a processing device to operate as desired or is independently or collectively processed You can command the device. The software and/or data may be any kind of machine, component, physical device, virtual equipment, computer storage medium or device, to be interpreted by or to provide instructions or data to the processing device. , or may be permanently or temporarily embody in a transmitted signal wave. The software may be distributed over networked computer systems and stored or executed in a distributed manner. Software and data may be stored in one or more computer-readable recording media.

The described embodiments of the present disclosure may also be practiced in distributed computing environments where certain tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.

The method according to the embodiment may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiment, or may be known and available to a person skilled in the art of computer software. Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floppy disks. - specially configured to store and execute program instructions such as magneto-optical media, and ROM, RAM, flash memory, and the like.

Hardware devices are included. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

A computing device may operate in a networked environment using logical connections to one or more remote computers, such as remote computer(s), via wired and/or wireless communications. The remote computer(s) may be workstations, server computers, routers, personal computers, portable computers, microprocessor-based entertainment devices, peer devices, or other common network nodes, generally comprising the components described for the computing device. includes many or all of The logical connections shown include wired/wireless connections to local area networks (LANs) and/or larger networks, eg, wide area networks (WANs). Such LAN and WAN networking environments are common in offices and companies, and facilitate enterprise-wide computer networks, such as intranets, all of which can be connected to a worldwide computer network, for example, the Internet.

As described above, although the embodiments have been described with reference to the limited drawings, those skilled in the art may apply various technical modifications and variations based on the above. For example, the described techniques are performed in a different order than the described method, and/or the described components of the system, structure, apparatus, circuit, etc. are combined or combined in a different form than the described method, or other components Or substituted or substituted by equivalents may achieve an appropriate result.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

200: terminal 210: processor
220: memory 222: Wi-Fi control command
224: software application command
230: communication module

Claims (18)

In the roaming method between access points according to the movement of the terminal,
detecting, by the terminal, a signal level between the terminal and a first access point currently connected for wireless communication; and
A roaming method comprising the step of starting a roaming process by the terminal in response to detecting that the signal level is below a predetermined level,
The roaming process is
determining whether the terminal is in a call or not;
transmitting a probe request frame at a first scan time in response to determining that the terminal is not in a call, wherein the first scan time is a scan time for each channel included in a frequency band of wireless communication for roaming;
Transmitting the probe request frame at a second scan time in response to determining that the terminal is on a call - The second scan time is a scan time for each channel included in a frequency band of wireless communication for the roaming, and the second scan time is shorter than the first scan time;
receiving, by the terminal, a probe response frame from a second access point; and
The roaming method comprising the step of the terminal connecting to the second access point. According to claim 1,
The first scan time is 40 ms or more and 60 ms or less, and the second scan time is 10 ms or more and 20 ms or less. According to claim 1,
The frequency band includes a first frequency band and a second frequency band, and the number of channels included in the first frequency band is less than the number of channels included in the second frequency band;
Transmitting the probe request frame at a second scan time in response to determining that the terminal is in a call
determining whether the frequency band includes the second frequency band; and
In response to determining that the frequency band includes the second frequency band, the terminal comprising the step of transmitting the probe request frame to each channel included in the second frequency band at the second scan time, How to roam. 4. The method of claim 3,
The wireless communication is Wi-Fi, the first frequency band is a 2.4 GHz band and the second frequency band is a 5 GHz band, the roaming method. 4. The method of claim 3,
The determining whether the frequency band includes the second frequency band includes determining based on a setting of the terminal. 4. The method of claim 3,
The determining whether the frequency band includes the second frequency band includes determining based on a frequency band used between the terminal and a first access point currently connected for wireless communication. In the roaming method between access points according to the movement of the terminal,
detecting, by the terminal, a signal level between the terminal and a first access point currently connected for wireless communication; and
A roaming method comprising the step of, by the terminal, initiating a roaming process in response to detecting that the signal level is below a predetermined level,
The roaming process is
determining whether the terminal is in a call or not;
determining, by the terminal, a frequency band for roaming - The frequency band includes a first frequency band and a second frequency band, and the number of channels included in the first frequency band is the number of channels included in the second frequency band less than the number of -;
transmitting a probe request frame at a first scan time in response to determining that the terminal is not in a call, wherein the first scan time is a scan time for each channel included in the first frequency band;
Transmitting the probe request frame at a second scan time in response to determining that the terminal is on a call and determining that the frequency band for roaming includes the second frequency band - the second scan time is a scan time for each channel included in the second frequency band, and the second scan time is shorter than the first scan time;
receiving, by the terminal, a probe response frame from a second access point; and
The roaming method comprising the step of the terminal connecting to the second access point. 8. The method of claim 7,
In response to determining that the frequency band for roaming is only the first frequency band, the method further comprising the step of transmitting the probe request frame in the first scan time. 8. The method of claim 7,
The first scan time is 40 ms or more and 60 ms or less, and the second scan time is 10 ms or more and 20 ms or less. 8. The method of claim 7,
The wireless communication is Wi-Fi, the first frequency band is a 2.4 GHz band and the second frequency band is a 5 GHz band, the roaming method. 8. The method of claim 7,
The step of determining, by the terminal, a frequency band for roaming includes determining based on a setting of the terminal. 8. The method of claim 7,
The step of determining, by the terminal, a frequency band for roaming includes determining based on a frequency band used between the terminal and a first access point currently connected for wireless communication. 8. The method of claim 7,
In response to determining that the terminal is in a call, the terminal performs the step of determining a frequency band for roaming. processor;
a communication module configured to provide roaming between the first access point and the second access point;
a terminal comprising a memory configured to store instructions that, when executed by the processor, cause the processor and the communication module to perform the method for roaming,
The method for roaming is
detecting, by the terminal, a signal level between the terminal and the first access point connected for the wireless communication; and
determining whether the terminal is in a call or not in response to detecting that the signal level is below a predetermined level;
transmitting a probe request frame at a first scan time in response to determining that the terminal is not in a call, wherein the first scan time is a scan time for each channel included in a frequency band of wireless communication for roaming;
Transmitting the probe request frame at a second scan time in response to determining that the terminal is on a call - The second scan time is a scan time for each channel included in a frequency band of wireless communication for the roaming, and the second scan time is shorter than the first scan time;
receiving, by the terminal, a probe response frame from a second access point; and
The terminal comprising the step of connecting with the second access point. 15. The method of claim 14,
The roaming is in accordance with the Wi-Fi standard, the first scan time is 40ms or more and 60ms or less, and the second scan time is 10ms or more and 20ms or less, the terminal. processor;
a communication module configured to provide roaming between the first access point and the second access point;
a terminal comprising a memory configured to store instructions that, when executed by the processor, cause the processor and the communication module to perform the method for roaming,
The method for roaming is
detecting, by the terminal, a signal level between the terminal and a first access point currently connected for wireless communication; and
initiating, by the terminal, a roaming process in response to detecting that the signal level is below a predetermined level;
The roaming process is
determining whether the terminal is in a call or not;
determining, by the terminal, a frequency band for roaming, wherein the frequency band includes a first frequency band and a second frequency band, and the number of channels included in the first frequency band is the number of channels included in the second frequency band less than the number of -;
transmitting a probe request frame at a first scan time in response to determining that the terminal is not in a call, wherein the first scan time is a scan time for each channel included in the first frequency band;
Transmitting the probe request frame at a second scan time in response to determining that the terminal is on a call and determining that the frequency band for roaming includes the second frequency band - the second scan time is a scan time for each channel included in the second frequency band, and the second scan time is shorter than the first scan time;
receiving, by the terminal, a probe response frame from a second access point; and
The terminal comprising the step of connecting with the second access point. 17. The method of claim 16,
The wireless communication is Wi-Fi, the first frequency band is a 2.4 GHz band and the second frequency band is a 5 GHz band, the first scan time is 40 ms or more and 60 ms or less, and the second scan time is 10 ms or more and 20 ms Below, the terminal. 18. The method of claim 17,
wherein the memory stores setting information regarding which frequency band to access with the second access point, and the terminal is configured to determine a frequency band for the roaming based on the setting information.

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