KR20130119123A - Internet telephone using dual band wifi and wifi-roaming method thereof - Google Patents

Abstract

PURPOSE: An internet phone using the Wi-Fi of the dual band and a Wi-Fi roaming method thereof can access a high AP (access point) having high signal intensity among the neighboring APs when the signal intensity of a frequency band currently using is diminished or cut-off during a phone call. CONSTITUTION: An AP searcher (140) searches APs existing in the around when a call disconnection or a reception level decrease through a reception signal intensity detector. A connection selecting unit (120) is preferentially connected to a first frequency band among a dual band of WLAN (wireless local area network). The connection selecting unit is connected to an AP having the highest signal intensity among neighboring APs searched through the AP searcher, when a signal intensity of a frequency band is detected to be equal to or lower than a predetermined threshold through the reception signal intensity detector. [Reference numerals] (110) Wireless LAN communication unit; (120) Access selection unit; (130) Reception signal intensity identification unit; (140) AP detecting unit; (150) AP information storing unit (profile management); (160) Output signal adjustment unit; (AA) 5GHz band; (BB) 2.4GHz band

Description

Internet phone using dual band Wi-Fi and its Wi-Fi roaming method {INTERNET TELEPHONE USING DUAL BAND WiFi AND WiFi-ROAMING METHOD THEREOF}

The present invention relates to an internet phone using a dual band Wi-Fi and a roaming method thereof, and more particularly, to expand the channel capacity of a wireless LAN (especially WiFi) in an internet phone using a wireless LAN. The present invention relates to an Internet phone and a method for roaming Wi-Fi, which uses both dual bands of the band, and improves call quality by enabling Wi-Fi roaming between both bands according to the dual band wireless signal strength.

Internet telephony refers to a service that enables telephone calls using voice over Internet Protocol (VoIP) technology. VoIP refers to a technology that carries voice signals through the internet network, which can improve network efficiency by transmitting voice and data to a single network, and has the advantage of lower rates than long distance calls such as long distance and international calls. have.

Recently, the Internet phone service using the VoIP technology is rapidly spreading, and accordingly, various functions are being integrated into one phone terminal to make a call through a different phone network.

In particular, as the technology of Wi-Fi has been expanded, voice call services using Wi-Fi have been introduced to Internet phones.

Wi-Fi is relatively fast compared to other communication networks and has a low communication cost, but the limitation is that wireless Internet is only available near an access point (AP) that enables wireless internet. In addition, since the number of terminals that can be accommodated by one access point is extremely limited, and the range of the wireless Internet is not wide, the access point should be installed in many places to enjoy the wireless Internet while moving. However, if the access point is installed indiscriminately, there is a problem in that the radio wave of the nearby access point causes interference and the speed of the wireless Internet is slowed down.

As such, since Wi-Fi does not support mobility, it is difficult to provide a seamless call service when applied to an Internet phone.

To this end, Wi-Fi was built in the existing 2.4 GHz frequency band with a 5 GHz frequency band that can reduce the interference of frequency and increase the number of users that an access point can accommodate, but still has an access point that supports the 5 GHz frequency band. There is still not much, and the call quality of the internet phone using Wi-Fi is still deteriorating.

The present invention was devised to solve the above problems, and the Internet phone is set to preferentially connect to an access point that supports any one of dual bands (2.4 GHz frequency band and 5 GHz frequency band) of the wireless LAN. Dual band Wi-Fi improves the call quality of Internet phones through seamless roaming between dual bands by providing access to the higher signal strength among nearby access points when the signal strength of the current frequency band decreases or drops during a call. An object of the present invention is to provide an internet phone and a method for roaming the Wi-Fi using the same.

To this end, according to the first aspect of the present invention, an Internet phone using a dual band Wi-Fi according to the present invention, a wireless LAN communication unit for transmitting and receiving voice data with a nearby access point via a wireless LAN (WiFi); A reception signal strength detection unit which measures the strength of a signal received through the WLAN communication unit at a predetermined period and detects a call drop or reception quality according to whether the measured signal strength is less than or equal to a preset threshold; An AP search unit searching for an access point (AP) in the vicinity when a call drop or reception quality degradation is detected through the reception signal strength detection unit; And first accessing a first frequency band among the dual bands of the WLAN, and when the signal strength of the currently connected frequency band is detected to be less than or equal to a preset threshold through the reception signal strength detection unit, the neighbor searched through the AP search unit. And a connection selector capable of roaming between dual bands by accessing the access point having the highest signal strength.

According to a second aspect of the present invention, a Wi-Fi roaming method in an internet phone of the present invention includes the steps of: registering, by the Internet phone, a primary AP using a first frequency band of dual bands of the WLAN; Preferentially accessing a registered primary access point and serving the service through the first frequency band; Measuring an intensity of a signal received from an access point to which the Internet telephone is currently connected, and detecting whether the call is disconnected according to whether the measured signal intensity is less than or equal to a preset threshold; Searching for access points in the vicinity when the call drop is detected; And performing dual inter-band roaming by accessing the access point having the highest signal strength among the searched neighboring access points.

According to a third aspect of the present invention, there is provided a method of roaming a Wi-Fi roaming in an Internet telephone of the present invention, the method comprising: registering, by an Internet telephone, a primary AP using a first frequency band of the dual bands of the WLAN; Firstly accessing a registered main access point to service a voice call through the first frequency band; Measuring an intensity of a signal received from an access point to which the Internet telephone is currently connected and detecting whether the measured signal intensity is equal to or less than a first predetermined reference value; Searching for access points in the vicinity if the signal strength of the currently connected access point is less than or equal to a preset first reference value; Detecting a sub-access point whose signal strength exceeds the preset first reference value among the searched neighboring access points; And roaming to an access point exceeding the preset first reference value when the signal strength of the currently accessing access point decreases below a second reference value lower than the preset first reference value. It is done.

According to a fourth aspect of the present invention, an automatic return method after roaming between dual bands in an internet phone of the present invention includes: searching for whether a primary AP, which is set around the predetermined interval, exists; Comparing the signal strength of the found main access point with the signal strength of the currently accessed sub access point (sub AP) when the main access point exists; When the signal strength of the primary access point is greater than the signal strength of the currently accessed sub-access point through the comparison, characterized in that it comprises the step of requesting the IP allocation to the primary access point.

According to the present invention, when an internet phone using Wi-Fi is in a 2.4 GHz frequency band or a 5 GHz frequency band, dual band roaming is performed in a 5 GHz frequency band or a 2.4 GHz frequency band with a high signal strength when the wireless signal strength drops below a threshold. By maintaining the call to perform the call has the effect of improving the quality of the call without interruption. Thereby, the mobility of an internet telephone can be improved.

In addition, it is possible to set the Internet phone to access the frequency band of any one of the dual bands first, and to set the connection waiting time when a call disconnection occurs while making a voice call through the currently connected frequency band, the frequency currently connected during the connection waiting. When the signal strength of the band increases, it automatically reconnects to the currently connected frequency band, thereby effectively roaming dual bands.

1 is a diagram illustrating a network configuration of an internet phone for using dual band Wi-Fi according to the present invention.
2 is a diagram illustrating Wi-Fi roaming operation between a main AP and a sub-AP according to the present invention.
3 is a diagram showing the configuration of an Internet telephone according to the present invention.
4 is a flowchart illustrating a Wi-Fi roaming method according to an embodiment of the present invention.
5 is a detailed flowchart of FIG. 4.
6 is a flowchart illustrating a Wi-Fi roaming method according to another embodiment of the present invention.
7 is a diagram illustrating a first method for automatic return after roaming between dual bands.
8 is a diagram illustrating a second method for automatic return after roaming between dual bands.
9 illustrates a third method for automatic return after roaming between dual bands.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The configuration of the present invention and the operation and effect thereof will be clearly understood through the following detailed description. Before describing the present invention in detail, the same components are denoted by the same reference symbols as possible even if they are displayed on different drawings. In the case where it is judged that the gist of the present invention may be blurred to a known configuration, do.

FIG. 1 is a diagram illustrating a network configuration of an internet phone for using dual band Wi-Fi according to the present invention, and FIG. 2 is a diagram illustrating Wi-Fi roaming operation between a main AP and a subAP according to the present invention.

First, referring to FIG. 1, the Internet phone 100 according to the present invention receives a counterpart through various heterogeneous phone networks such as an IP network 400-1, a wired telephone network 400-2, and a mobile communication network 400-3. A voice call can be made with the terminal 500.

The receiving terminal 500 may include an IP terminal 510, a wired terminal 520, a portable terminal 530, and the like, depending on the type of terminal that can be connected to each telephone network (IP network, wired telephone network, mobile communication network, etc.). .

In particular, the Internet phone 100 according to the present invention is connected to the IP network 400-1 through the access point (200, 3000) of the surroundings to wirelessly provide a voice call with the receiving terminal 500 based on the VoIP method. And are offered.

At this time, the Internet phone 100 must be located within a predetermined distance with respect to the place where the access points 200 and 300 are installed to access the IP network 400-1 through the wireless LAN.

In an embodiment of the present invention, an access point that can be connected to the IP network 400-1 is illustrated by dividing a primary access point (primary AP) 200 and a sub access point (sub AP) 300.

The primary access point 200 refers to a device that preferentially accesses an existing access point. The main access point 200 communicates through any one of the dual bands.

For example, when the main access point 200 supports the 5 GHz frequency band with low frequency interference and can accommodate many users, the voice signal received when the voice signal is received from the Internet telephone 100 through the 5 GHz frequency band. To the receiving terminal 500 through the IP network 400-1.

The main access point 200 is installed in a place where the user mainly uses the Internet phone, and the Internet phone registers in advance so as to automatically access the Internet phone.

The sub access point 300 refers to all of the access points that exist in the periphery except the main access point 200. The sub access point 300 may support a frequency band of the same band as the main access point 200 and may support a frequency band of a different band from the main access point 200.

In addition, the sub-access point 300 is installed in various places by location and area.

Accordingly, the Internet telephone 100 according to the present invention registers the main access point 200 to use any one of the dual bands as the main, and preferentially accesses the registered main access point 200. .

Then, as shown in FIG. 2, when the signal strength (Received Signal Strength Indicator (RSSI)) of the main access point that is currently connected by the movement of the terminal or the network environment decreases or is cut off, the Internet phone 100 is connected to a plurality of existing ones. The roaming of the sub-access points 300-1, 300-2, and 300-3 into the frequency band of the access point having the highest signal strength can increase the mobility of the Internet telephone.

For example, if the signal strength decreases during service over the first 5 GHz frequency band, roaming to the 2.4 GHz frequency band, then reducing the signal strength in the 2.4 GHz frequency band or access point in the 5 GHz frequency band to preferentially connect to the surroundings If is present can automatically return back to the 5GHz frequency band.

In the present embodiment, the 5 GHz frequency band and the 2.4 GHz frequency band are described in detail with respect to the dual band of the Wi-Fi. However, the present invention is not limited thereto and may include the new band if there is a new wireless band. In order to include this, in some descriptions, the dual band will be divided into a first frequency band and a second frequency band.

3 is a diagram showing the configuration of an Internet telephone according to the present invention.

Internet phone 100 according to the present invention is a wireless LAN communication unit 110, connection selection unit 120, received signal strength detection unit 130, AP search unit 140, AP information storage unit 150, output signal It includes an adjusting unit 160.

The WLAN communication unit 110 transmits and receives a voice signal with the access point within a certain distance of the place where the access point is installed.

The received signal strength detector 130 measures the strength of a signal received through the WLAN communication unit 110 at regular intervals and disconnects or receives a call level depending on whether the measured signal strength is less than or equal to a preset threshold. Is detected. Here, the preset threshold is set differently according to the detection condition of disconnection and reception level. That is, the disconnection of the call is determined based on the minimum signal strength of about -100dbm, and the reception level is determined to be excellent, good, weak, etc. based on the threshold values of -68dbm and -75dbm.

The reception signal strength detection unit 130 can detect only one of the disconnection or reception level by setting only one threshold value, and by setting each threshold value, detects not only the disconnection but also the reception level of the call. Can provide call quality.

In addition, the reception signal strength detector 130 may measure the signal strengths of the neighboring access points searched using the received signal when scanning the neighboring access points through the AP search unit 140.

The AP search unit 140 searches for all access points in the vicinity through the WLAN communication unit 110 when a call drop or reception level reduction is detected through the reception signal strength detector 130. In the discovery method, a terminal transmits a probe request frame to a dual band to all access points existing around the terminal, and the access point receiving the terminal transmits a probe response frame to the terminal, thereby providing the presence of the access point. Is made by notifying.

In this case, all the access points in the vicinity may include the main access point, and may include only the sub-access points except the main access point.

For example, when roaming from a main access point to a sub access point, only sub access points will exist when searching for neighboring APs, and conversely, when roaming from a sub access point to a main access point, main access points and sub access points when searching for neighboring APs. May be present.

The AP search unit 140 stores information on the searched neighboring access points in the AP information storage unit 150 and manages a profile of the access point.

The output signal controller 160 presets the strength of the wireless signal to be transmitted to the currently accessed access point when the signal strength (RSSI) detected by the received signal strength detector 130 decreases with respect to the currently connected access point. Adjust according to the reduction level.

For example, as shown in Table 1 below, an optimal output power may be defined according to the transmission rate of each WLAN standard. The output signal adjusting unit 160 may extract the distance between the access point and the terminal and the transmission rate from the signal strength received from the access point, and adjust the optimum output power according to the extracted transmission speed.

WLAN specification rate Output power 802.11b 1M, 2M, 55M, 11M 18 dBm or more 802.11g 6M, 9M, 12M, 18M 18 dBm or more 24M, 36M 16 dBm or more 48M, 54M 14 dBm or more 802.11n MCS0, MCS1, MCS2 18 dBm or more MCS3, MCS4 16 dBm or more MCS5, MCS6, MCS7 14 dBm or more

The operation of the output signal adjusting unit 160 is meaningless to perform when the call is disconnected because the signal strength of the currently accessed access point is lowered to the minimum. That is, the operation start condition may be set to control the output signal according to the signal strength of the access point when the reception level corresponds to good or good signal strength.

The access selector 120 accesses one main access point (200 in FIG. 1) to use a specific band of one of the dual bands of the WLAN as a main when transmitting and receiving a voice signal through the WLAN communication unit 110. It registers with the information storage part 150, and sets it to preferentially connect to the one main access point (200 of FIG. 1) registered. The setting may be designated using a service set identification (SSID) for a primary access point (200 in FIG. 1).

In addition, the connection selector 120 uses the service through a specific band among the dual bands, and then the signal strength of the frequency band of the specific band currently connected through the reception signal strength detection unit 130 is less than or equal to a preset threshold. When the number is decreased or dropped, the AP access unit 140 accesses the sub access point having the highest signal strength among the neighboring sub access points, and maintains the service through the dual band.

The surrounding sub access points may be in the same band as the main access point or may support different bands. For example, when the main access point is a 2.4 GHz frequency band, the sub access point may be an access point supporting the 2.4 GHz frequency band or an access point supporting the 5 GHz frequency band. In addition, after roaming, the connection selector 120 may be used. ) May access another access point depending on whether the signal strength of the frequency band currently being accessed is reduced or dropped. At this time, when the main access point is located through the search of the neighboring access point, the main access point is automatically connected regardless of the signal strength of the access point.

In addition, the connection selector 120 determines whether the state of the terminal is busy or not when the signal strength of the frequency band currently connected through the reception signal strength detector 130 decreases or drops below a preset threshold. Depending on the state, additional actions can be controlled.

That is, if the terminal is in the initial (idle) state, the above-described operation is followed. If the terminal is busy, the terminal automatically waits for a predetermined time in the currently connected frequency band. After maintaining the automatic connection for a certain period of time, when the Internet phone 100 enters the wireless Internet communication area again and the signal strength of the frequency band waiting to be connected increases, reconnect to the frequency band of the corresponding access point. do.

Then, the dual band roaming method and the automatic return method after roaming when the Wi-Fi connection using the Internet phone will be described in detail.

For reference, in order to help the understanding of the present invention, a primary access point (primary AP) supports a 5 GHz frequency band (or first frequency band) in which quality is superior among dual bands of a WLAN, and a sub access point (sun AP). The following description will be limited to devices that support the 2.4 GHz frequency band (or the second frequency band).

FIG. 4 is a flowchart illustrating a method of roaming Wi-Fi in the 2.4 GHz frequency band when a call drop occurs in the dual band 5 GHz frequency band.

First, the Internet phone registers information on the primary AP of the 5 GHz frequency band (or the first frequency band) of the dual bands of the wireless LAN in the AP information storage unit, and pre-registers when accessing the wireless Internet. A connection standard is set so that the access point can be preferentially connected (S100).

Thereafter, the Internet telephone accesses the main access point according to the set access standard to use the service through the 5 GHz frequency band (S110).

Thereafter, periodically measuring the strength of the signal received from the main access point that is currently connected (S120), and determines whether the measured signal strength (RSSI) is less than or equal to a preset threshold (S130). . The preset threshold may apply about -100dbm on average, but this may vary in a terminal environment or a network environment.

If the disconnection is not detected in the frequency band of the main access point currently being accessed, the previous connection is maintained as it is (S140).

On the contrary, when the call disconnection is detected in the frequency band of the main access point currently connected, the Internet phone first checks the state of the terminal through the connection selection unit (S150).

When the state of the terminal is the initial state (idle), the sub-access point for the 2.4GHz frequency band (or the second frequency band) of the dual band is searched for around (S160).

Thereafter, an attempt is made to access an access point having the highest signal strength among the searched sub access points (S170). This is a case where there is no registration for the sub-access point in the profile of the Internet phone or the sub-access point is registered in the profile but there is no sub-access point already registered in the vicinity.

On the other hand, in the above step S150, if the state of the terminal is busy (busy) state, as shown in Figure 5 waits for the automatic connection to the main access point that is currently connected (S151, S152). Here, the term "meaning" means a predetermined predetermined time and is a waiting time for disconnecting or reconnecting according to an arbitrary event while maintaining automatic connection for a predetermined time.

The Internet telephone checks whether the signal strength of the main access point is increased or whether the disconnection is maintained for a predetermined time (S153).

When the Internet phone enters into the area where the wireless Internet communication is possible again for a certain time and the signal strength of the main access point waiting for access is increased, it reconnects to the frequency band of the main access point waiting for access (S154). .

Alternatively, if the signal strength of the main access point is detected as being disconnected below the preset threshold for a predetermined time, step S160 is performed to search for sub-access points for the 2.4 GHz frequency band among the dual bands.

FIG. 6 illustrates a method of automatically roaming by determining, in units of levels, that a call drop occurs gradually because the signal strength of the currently accessed access point is not lowered by a preset threshold.

Referring to FIG. 6, first, an Internet phone registers a primary AP of a 5 GHz frequency band (or a first frequency band) of dual bands of a WLAN (S200). Then, the connection standard is set so that the Internet telephone can first access the main access point registered in advance when connecting to the wireless Internet.

Subsequently, the Internet telephone accesses the main access point according to the set access standard to service the voice call through the 5 GHz frequency band (S210 and S220).

Thereafter, the strength of the signal received from the currently accessed main access point is periodically measured (S230), and it is detected whether or not the measured signal strength is less than or equal to the first reference value (m). The first reference value m is a reference value for determining whether the reception level is excellent or weak.

That is, when the measured signal strength exceeds the first reference value, it is determined that the signal strength is excellent and maintains the voice call service in the 5 GHz frequency band currently being accessed.

Alternatively, if the measured signal strength is less than or equal to the first reference value, it is determined that the signal strength of the currently connected 5 GHz frequency band is weak, and the sub-access point for the 2.4 GHz frequency band among the dual bands is searched for (S250).

Thereafter, an access point whose signal strength exceeds the first reference value m is detected in the found sub access points (S260). An access point exceeding the first reference value m may be an access point registered in advance in a profile. Alternatively, the access point may be an access point that is not registered in the profile in advance and found through neighboring AP discovery. In this case, the searched access point may be one, but if there are a plurality of access points, the access point having the highest signal strength may be selected and detected.

Thereafter, the signal strength of the currently accessed main access point is checked again to determine whether the signal strength is less than or equal to the second reference value n lower than the first reference value m (S270).

This process is to determine the case where the reception level is weaker than the first reference value but is reduced to less than or equal to the second reference value n.

Thereafter, when the signal strength decreases below the second reference value n, the device automatically roams to the sub-access point detected in the process (S280).

Through this process, in another exemplary embodiment of the present invention, when the reception quality is deteriorated, call quality may be improved despite the movement of the Internet phone by automatically roaming to a frequency band of another access point.

Although the example of roaming from the 5 GHz frequency band to the 2.4 GHz frequency band has been described above in the embodiments of FIGS. 4 and 6, the present invention is not limited thereto, and the 2.4 GHz frequency band is applied to the 2.4 GHz frequency band or the 2.4 GHz frequency band to the 5 GHz frequency band. Roaming with is also applicable.

7 is a diagram illustrating a first method for automatic return after roaming between dual bands.

Although the automatic return method of FIG. 7 does not cause a special obstacle in the dual band, there is a main access point in the vicinity, and illustrates a process of automatically returning according to the connection standard.

The Internet phone roaming from the 5 GHz frequency band to the 2.4 GHz frequency band detects whether a major access point in the 5 GHz frequency band exists around a certain period (for example, one minute) (S300).

If there is a main access point in the vicinity, the signal strength of the found main access point is compared with the signal strength of the currently accessed sub access point (S310).

When the signal strength of the main access point is greater than the signal strength of the sub access point, an IP allocation request is made to the main access point (S320 and S330). The access information of the access point for the existing 2.4 GHz frequency band is maintained.

Subsequently, if the IP assignment is normal, an attempt is made to access the 5 GHz frequency band of the main access point.

FIG. 8 illustrates a process of automatically returning when a call disconnection failure occurs due to a decrease in signal strength of a currently connected band after roaming between dual bands.

Internet phones roaming from the 5 GHz frequency band to the 2.4 GHz frequency band periodically measure the signal strength for the frequency band currently being accessed.

In particular, during the call, the signal strength of the access point currently being accessed decreases below the preset threshold to detect whether the call is dropped (S400).

If the call disconnection occurs as described above, for a short time, it waits for the automatic connection to the currently connected sub-access point (S410).

Thereafter, the Internet telephone checks whether the signal strength of the currently accessed sub access point is increased or whether the disconnection is maintained for a predetermined time (S420).

If the Internet phone enters into the area where the wireless Internet communication is possible again for a predetermined time and the signal strength of the sub access point currently waiting for access increases, re-connects to the frequency band of the sub access point currently waiting for access (S430). .

Alternatively, if the signal strength for the sub access point is still detected as being disconnected below a preset threshold, all access points in the vicinity are searched for (S440).

Thereafter, it is determined whether a main access point exists in all the searched access points (S450).

If there is a main access point, it ignores all searched access points and attempts to connect to the main access point according to a preset connection specification (S460).

If there is no main access point, an attempt is made to access the sub access point having the highest signal strength among the found sub access points (S470).

FIG. 9 corresponds to a process of automatically returning a signal strength of a currently roaming frequency band based on a first reference value and a second reference value, according to a reception level, as in the roaming process of FIG. 6.

That is, the signal strength of the currently connected sub access point (sub AP) is periodically measured to detect whether the measured signal strength is less than or equal to the first reference value m (S500 and S510).

If the measured signal strength exceeds the first reference value, it is determined that the signal strength is excellent and maintains the voice call service in the 2.4 GHz frequency band currently being accessed.

Or, if the measured signal strength is less than or equal to the first reference value, it is determined that the signal strength of the currently accessed access point is weak, and all access points for the dual band are searched around (S520).

Thereafter, an access point whose signal strength exceeds the first reference value m is detected in all searched access points (S530). An access point exceeding the first reference value m may include a main access point or only a sub access point.

Thereafter, the signal strength of the currently accessed main access point is checked again to determine whether the signal strength is less than or equal to the second reference value n lower than the first reference value m (S540).

As a result of the check, if the signal strength does not decrease below the second reference value n, the current state is maintained as it is and the searched access point detects an access point whose signal strength exceeds the first reference value m (S530).

As a result of the check, when the signal strength decreases below the second reference value n, the device automatically roams to the access point detected in the process (S550). At this time, when the detected access point includes the main access point and the sub access point, the roaming priority is performed to the main access point.

The foregoing description is merely illustrative of the present invention, and various modifications may be made by those skilled in the art without departing from the spirit of the present invention. For example, the dual band of Wi-Fi has been described using the 5 GHz frequency band and the 2.4 GHz frequency band as an example. However, the present invention is not limited thereto and may include a new frequency band capable of wireless internet. If the new frequency band is superior in quality to the 5GHz frequency band, it could be applied instead of the 5GHz frequency band.

Therefore, the embodiments disclosed in the specification of the present invention are not intended to limit the present invention. The scope of the present invention should be construed according to the following claims, and all the techniques within the scope of equivalents should be construed as being included in the scope of the present invention.

100: Internet call 200: main access point
300: sub access point 400-1: IP network
400-2: Wireline Network 400-3: Mobile Communication Network
410: SIP server 500: receiving terminal
510: IP terminal 520: wired terminal
530: mobile terminal 110: wireless LAN communication unit
120: connection selector 130: received signal strength detection unit
140: AP search unit 150: AP information storage unit
160: output signal control unit

Claims (20)

In the Internet phone to provide a voice call service using a wireless LAN (WiFi),
A wireless LAN communication unit for transmitting and receiving a voice signal with a neighboring access point through the wireless LAN;
A reception signal strength detection unit which measures the strength of a signal received through the WLAN communication unit at predetermined intervals and detects a call drop or reception quality according to whether the measured signal strength (RSSI) is less than or equal to a preset threshold;
An AP search unit searching for an access point (AP) in the vicinity when a call drop or reception level reduction is detected through the reception signal strength detector; And
The first frequency band of the dual bands of the WLAN is preferentially connected, and if the signal strength of the currently connected frequency band is detected below the preset threshold through the received signal strength detector, Connection selector for roaming between dual bands by accessing the access point with the highest signal strength among the access points
Internet phone using a dual band WiFi, characterized in that it comprises a. The method of claim 1,
The connection selector
And pre-setting a primary access point (Primary AP) using the first frequency band in order to preferentially access the first frequency band. 3. The method of claim 2,
Among the access points in the vicinity searched through the AP search unit, the access point having the highest signal strength is
An internet telephone using a dual band Wi-Fi, characterized in that the sub-access point (sub AP) supporting the first frequency band or the second frequency band of the dual band. 3. The method of claim 2,
The connection selector
If the frequency band currently being accessed after roaming is the second frequency band of the dual band,
When a neighboring access point found through the AP search unit includes a primary AP supporting the first frequency band, the AP is automatically connected to the main access point regardless of the signal strength. Dual band Wi-Fi internet calling. The method of claim 1,
The first frequency band is a 5GHz frequency band or 2.4GHz frequency band dual-band Internet phone using the Internet. The method of claim 1,
The connection state portion
When the signal strength of the currently connected frequency band is detected below a preset threshold, when the terminal is in a call, the dual band Wi-Fi is characterized by waiting for automatic connection to the currently connected frequency band for a predetermined time. Used internet phone. The method according to claim 6,
The connection state portion
If the signal strength of the currently connected frequency band is increased again during the predetermined time period, the Internet phone using the dual band Wi-Fi, characterized in that for reconnecting to the currently connected frequency band. The method of claim 1,
An output signal adjusting unit for adjusting the strength of a radio signal to be transmitted to the access point currently connected according to a decrease level when the signal strength detected by the received signal strength detector decreases with respect to the currently connected access point;
Internet phone using a dual band WiFi, characterized in that it further comprises. A method of accessing an Internet phone that provides a voice call service using a wireless LAN (WiFi),
Registering, by the Internet telephone, a primary AP using a first frequency band of the dual bands of the WLAN;
Preferentially accessing a registered primary access point and serving the service through the first frequency band;
Measuring an intensity of a signal received from an access point to which the Internet telephone is currently connected, and detecting whether the call is disconnected according to whether the measured signal intensity is less than or equal to a preset threshold;
Searching for access points in the vicinity when the call drop is detected; And
Performing dual band roaming by accessing the access point having the highest signal strength among the searched neighboring access points
WiFi roaming method in the Internet phone comprising a. The method of claim 9,
Connecting to the access point having the highest signal strength among the searched neighboring access points,
Wi-Fi roaming method in the Internet phone, characterized in that for connecting to a sub-access point (sub AP) supporting the first frequency band or the second frequency band of the dual band. 11. The method of claim 10,
In the step of accessing the access point having the highest signal strength among the searched neighboring access points,
When the currently accessed access point is a sub access point and the searched neighboring access points include the main access point, the main access point is automatically connected to the main access point regardless of the signal strength of the access points. Roaming methods on internet phones. The method of claim 9,
And the first frequency band is a 5 GHz frequency band or a 2.4 GHz frequency band. The method of claim 9,
If the call drop is detected,
Determining whether the terminal is busy;
Waiting for an automatic connection to the currently accessed access point for a predetermined time when the terminal is busy;
If the signal strength of the currently connected access point is increased again for the predetermined time, reconnect to the currently connected access point, and if the signal strength of the currently connected access point is equal to or less than a preset threshold, the neighboring access Searching for points
WiFi roaming method in the Internet phone comprising a. A method of accessing an Internet phone that provides a voice call service using a wireless LAN (WiFi),
Registering, by the Internet telephone, a primary AP using a first frequency band of the dual bands of the WLAN;
Firstly accessing a registered main access point to service a voice call through the first frequency band;
Measuring an intensity of a signal received from an access point to which the Internet telephone is currently connected and detecting whether the measured signal intensity is equal to or less than a first predetermined reference value;
Searching for access points in the vicinity if the signal strength of the currently connected access point is less than or equal to a preset first reference value;
Detecting an access point whose signal strength exceeds the preset first reference value among the searched neighboring access points; And
Roaming to an access point exceeding the preset first reference value when the signal strength of the currently accessed access point decreases below the second reference value lower than the preset first reference value
WiFi roaming method in the Internet phone comprising a. 15. The method of claim 14,
And the first reference value and the second reference value are reference values for detecting the reception level of the internet telephone by the signal strength received from the currently accessing access point. 15. The method of claim 14,
Among the searched neighboring access points, an access point whose signal strength exceeds the predetermined first reference value is:
And a sub access point (sub AP) supporting a first frequency band or a second frequency band of the dual bands. 17. The method of claim 16,
When the signal strength of the currently connected access point decreases below a second reference value lower than the preset first reference value,
If the currently accessed access point is a sub-access point due to roaming, and a main access point is included in the access point exceeding the preset first reference value, an access point is attempted to the main access point, and the main access point Wi-Fi roaming method in an Internet telephone, characterized in that if the does not exist to try to connect from the detected access point to the sub-access point with the highest signal strength. As a method of automatically returning after roaming between dual bands in an Internet phone providing a voice call service using a wireless LAN (WiFi),
Searching for whether a predetermined primary AP exists around a predetermined period;
Comparing the signal strength of the found main access point with the signal strength of the currently accessed sub access point (sub AP) when the main access point exists; And
Requesting IP allocation to the primary access point if the signal strength of the primary access point is greater than that of the currently accessed sub access point through the comparison;
Automatic return method after roaming between dual bands in the Internet phone comprising a. The method of claim 18,
The primary access point (primary AP) is a pre-roaming roaming method after dual-band roaming in the Internet phone, characterized in that the pre-set to the terminal in order to access prior to the access point existing in the vicinity. The method of claim 19,
The primary AP and the sub-access point (sub AP) is the same band or support different bands, characterized in that the automatic return after roaming between dual bands in the Internet phone.

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