KR100701039B1 - Hand-off Method for performing continuously communication and Apparatus of the same - Google Patents

Hand-off Method for performing continuously communication and Apparatus of the same Download PDF

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Publication number
KR100701039B1
KR100701039B1 KR1020050079875A KR20050079875A KR100701039B1 KR 100701039 B1 KR100701039 B1 KR 100701039B1 KR 1020050079875 A KR1020050079875 A KR 1020050079875A KR 20050079875 A KR20050079875 A KR 20050079875A KR 100701039 B1 KR100701039 B1 KR 100701039B1
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KR
South Korea
Prior art keywords
access point
information
mac
wireless
communication terminal
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KR1020050079875A
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Korean (ko)
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KR20070027924A (en
Inventor
오승주
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삼성전자주식회사
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W36/00Hand-off or reselection arrangements
    • H04W36/08Reselecting an access point
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W36/00Hand-off or reselection arrangements
    • H04W36/0005Control or signalling for completing the hand-off
    • H04W36/0011Control or signalling for completing the hand-off for data session or connection
    • H04W36/0027Control or signalling for completing the hand-off for data session or connection for a plurality of sessions or connections, e.g. multi-call, multi-bearer connections
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W36/00Hand-off or reselection arrangements
    • H04W36/34Reselection control
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04WWIRELESS COMMUNICATION NETWORKS
    • H04W36/00Hand-off or reselection arrangements
    • H04W36/34Reselection control
    • H04W36/38Reselection control by fixed network equipment

Abstract

The present invention relates to a handoff method and apparatus for maintaining continuity of communication, wherein a wireless communication terminal which is a handoff apparatus of the present invention comprises a memory unit for storing first connection necessary information required for connecting to a first access point. In response to the first access need information being received from the first access point, the first access point is used to communicate with the first access point, and a handoff occurs during the communication. A second part determined by determining a second access point to be newly connected based on a wireless unit requesting the neighboring access points for the second connection necessary information required to access each, and a second access need information received from the neighboring access points. It has a control unit that performs a communication connection with an access point. Accordingly, by using the pre-stored connection required information to obtain the information necessary for the connection from the peripheral access point at the time of hand-off, it is possible to shorten the time required for acquiring the connection necessary information without interruption of the communication being performed. Continuity can be provided.
Wireless data communication, handoff, access point, terminal

Description

Hand-off method for performing continuously communication and Apparatus of the same

1 is a view showing a general configuration of a wireless data communication system using a composite access point,

2 illustrates an example in which a handoff occurs in a wireless data communication system;

3 is a flowchart illustrating a handoff process of a conventional wireless communication terminal;

4 is a block diagram showing a preferred embodiment of a wireless communication terminal for more quickly processing a handoff according to a change of a communication connected access point according to the present invention;

5 is a block diagram showing a preferred embodiment of an access point applied for performing a quick handoff of a wireless communication terminal according to the present invention;

FIG. 6 is a diagram illustrating a hierarchical structure and packet transmission paths of the wireless communication terminal and the access point of FIGS. 4 and 5.

7 illustrates an example of respective IP and MAC information assigned and interchanged to an access point and a wireless communication terminal.

8 is a view for explaining a communication connection method with an access point during handoff according to the present invention;

9 is a flowchart illustrating an initial registration process of a wireless data communication system according to a method for performing a fast handoff according to the present invention;

10 is a flowchart illustrating a preferred embodiment of a handoff method capable of providing continuity of a call by shortening a time required for performing a handoff in a wireless communication terminal according to the present invention.

The present invention relates to a method and a device for handoff between access points, and more particularly, by a neighboring access point out of the wireless network formed by the currently connected access point while performing a voice call using a wireless communication terminal. The present invention relates to a method and apparatus for handoff between access points to enable more stable and quick handoff so as not to interfere with a call when a channel reconnection is required due to movement to a formed wireless network.

Hand off refers to the switching of a wireless terminal to a nearby access point in order to communicate on an optimal wireless link while moving. The process of performing the handoff will be briefly described. A process of changing a wireless channel, that is, a process of changing a wireless channel, such as setting a wireless channel with a new access point and releasing a channel set with a previous access point, is performed. In parallel with the channel change process, the process consists of rerouting as the data transmission path in the network changes.

1 is a diagram illustrating a general configuration of a wireless data communication system using a complex access point.

As shown, a wireless data communication system using a complex access point, a wireless communication terminal 10, an access point (AP) 20, a wired LAN (LAN) 30, the Internet (internet) ( 40), Public Switched Telecommunications Network (PSTN) 50, Private Branch Exchange (PBX) 60, and Wireless Local Area Network (WLAN) 80, etc. do.

A wired LAN 30 and a private exchange 60 are connected to the access point 20 performing short range wireless data communication with the wireless communication terminal 10 through the wireless LAN 80, respectively. The wired LAN 30 is connected to the Internet network 40 to which the personal computer 72 is connected. The private exchange 60 is connected to the public telephone network 50 to which the telephone 74 is connected.

Hereinafter, a transmission path of a voice packet and a data packet in the wireless data communication system having the above configuration will be briefly described.

Here, the voice packet refers to a packet that requires real-time transmission to enable conversation between callers, and a data packet refers to a packet of data that does not need to be transmitted in real time, unlike a voice packet.

The wireless communication terminal 10 may be classified into a data dedicated terminal that transmits and receives only data packets, a voice dedicated terminal that transmits and receives only voice packets, and a complex communication terminal capable of transmitting and receiving voice and data packets together. A wireless communication terminal 10 such as a wireless Voice over Internet Protocol (VoIP) terminal 11, a personal digital assistant (PDA) 13, a portable computer 15 equipped with a wireless LAN card, or the like is used to transmit voice or data in a packet form. To transmit via wireless LAN 80. In this case, the wireless communication terminal 10 converts not only general data but also a voice signal input from a user into pulse code modulation (PCM) voice data, and compresses it again to a signal frame set in a WLAN communication standard. Voice data is also transmitted to the access point 20 in the form of a packet.

The access point 20 that receives the voice or data packet from the wireless communication terminal 10 divides the received packet into a voice packet and a data packet and outputs the received packet as a path for transmission to the corresponding destination. That is, if the received packet is a voice packet, the access point 20 outputs the received voice packet to the corresponding path so as to be transmitted to the telephone 74 via the private switch 60 and the public telephone network 50. In addition, if the received packet is a data packet, the access point 20 outputs the received data packet to the corresponding path to be transmitted to the personal computer 72 through the wired LAN 30 and the Internet network 40.

The personal computer 72 receives the data packet transmitted from the wireless communication terminal 10 via the access point 20, the wired LAN 30, and the Internet network 40, and transmits the corresponding data packet to the wireless communication terminal ( 10) Perform the function of transmitting to the side.

The telephone 74 receives voice packets transmitted from the wireless communication terminal 10 via the access point 20, the private switchboard 60, and the public telephone network 50, and correspondingly communicates with the wireless communication terminal 10 side. Perform voice call function.

On the other hand, when a data packet is received from the personal computer 72 via the Internet network 40 and the wired LAN 30, the access point 20 converts the received packet data into a wireless LAN communication standard to the wireless LAN (80) ) Is transmitted to the wireless communication terminal 10 as a destination. In addition, when PCM voice data is received from the telephone 74 via the public telephone network 50 and the private switchboard 60, the access point 20 converts the received voice data into a voice packet to convert the wireless LAN 80. Through the transmission to the destination wireless communication terminal 10 side.

When the wireless communication terminal 10 moves from the network formed by the currently located access point 20 to the network formed by the neighboring access points, handoff occurs.

2 is a diagram illustrating an example in which a handoff occurs in a wireless data communication system.

As shown, if a handoff occurs as the wireless VoIP terminal 11 moves from the service area 22a of the first access point 22 to the service area 24a of the second access point 24, wireless The VoIP terminal 11 disconnects from the first access point 22 and wirelessly connects to the second access point 24 to perform voice communication. At this time, the second access point 24 and the wireless VoIP terminal 11 perform a wireless connection due to handoff based on IP and medium access control (MAC) information of the other party obtained through information exchange with each other at predetermined time intervals. .

3 is a flowchart illustrating a handoff process of the wireless communication terminal 10 according to the related art.

When the wireless VoIP terminal 11 generates voice communication data (S11), ARP (Address Resolution Protocol) table information including IP and MAC information for the first access point 22 to which the wireless VoIP terminal 11 belongs The signal requesting the signal is transmitted to the first access point 22 (S13). The first access point 22 transmits ARP table information including IP and MAC information of the first access point 22 to the wireless VoIP terminal 11 in response to the request signal of the ARP table information (S15). The wireless VoIP terminal 11 receives the ARP table information transmitted from the first access point 22 and transmits voice data to the first access point 22 based on the received ARP table information (S17).

The first access point 22 receives voice data from the wireless VoIP terminal 11, transmits the voice data to the corresponding destination, and receives the voice data from the corresponding destination. Upon receiving the voice data, a signal for requesting ARP table information including IP and MAC information for the wireless VoIP terminal 11 is transmitted to the wireless VoIP terminal 11 (S19). The wireless VoIP terminal 11 transmits ARP table information including IP and MAC information of the wireless VoIP terminal 11 to the first access point 22 in response to the request signal of the ARP table information (S21). The first access point 22 receives the ARP table information transmitted from the wireless VoIP terminal 11 and transmits voice data to the wireless VoIP terminal 11 based on this (S23).

Meanwhile, if the wireless VoIP terminal 11 moves from the wireless network of the first access point 22 to the wireless network of the second access point 24 and a handover condition occurs (S25), the first access point 22 As a result of the disconnection, the voice data communication, which is being performed for a predetermined time (300 seconds) until the connection with the second access point 24 is completed, becomes impossible.

That is, the wireless VoIP terminal 11 performs the process described below to connect to the second access point 24 when a handoff occurs. During this process the call will not be accepted.

When the wireless VoIP terminal 11 moves from the wireless network of the first access point 22 to the wireless network of the second access point 24, the wireless VoIP terminal 11 is connected to the second access point 24 to which the wireless VoIP terminal 11 belongs. A signal for requesting ARP table information including IP and MAC information is transmitted to the second access point 24 (S27). The second access point 24 transmits the ARP table information including the IP and MAC information of the second access point 24 to the wireless VoIP terminal 11 in response to the request signal of the ARP table information (S29). The wireless VoIP terminal 11 receives the ARP table information transmitted from the second access point 24 and transmits voice data to the second access point 24 based on the ARP table information (S31).

When the second access point 22 receives voice data to be transmitted to the wireless VoIP terminal 11, the second access point 22 transmits a signal requesting ARP table information including IP and MAC information to the wireless VoIP terminal 11. (S33). The wireless VoIP terminal 11 transmits ARP table information including IP and MAC information of the wireless VoIP terminal 11 to the second access point 24 in response to the request signal of the ARP table information (S35). The second access point 24 receives the ARP table information transmitted from the wireless VoIP terminal 11 and transmits voice data to the wireless VoIP terminal 11 based on this (S37).

Therefore, when the handoff occurs, the wireless VoIP terminal 11 must newly update the MAC information, which is unique identification information of the access points, while the MAC information update process (S27 to S35) is performed (about 300 seconds) before. There is a problem that the communication service that is being performed is interrupted.

As such, the wireless communication terminal 110 and the access point 200 exchange ARP tables including IP and MAC information with each other at predetermined time intervals (for example, 300 seconds). The access point 20 obtains an ARP table composed of IP and MAC information of the wireless communication terminal 10, and the wireless communication terminal 10 recognizes BSSID (Basic) recognized as common IP and MAC information of the access point 20. Obtain an ARP table consisting of Service Set Identification. The wireless data communication connection between the wireless communication terminal 10 and the access point 20 is enabled using each of these ARP tables.

However, the wireless communication terminal 10 and the access point 20 do not store the corresponding information of each ARP table, respectively, and use or delete the wireless communication connection depending on whether they are used at a time provided only at predetermined time intervals. Therefore, when a handoff occurs from the first access point 22 to the second access point 24, the wireless communication terminal 10 takes 300 to acquire ARP table information of the second access point 24. There is a problem that the communication connection is disconnected for a second).

An object of the present invention for solving the above problems is to provide a handoff method and apparatus that can maintain the continuity of communication when a handoff occurs during the wireless data communication using the access point.

Another object of the present invention is to perform a process performed to obtain information necessary for communication connection with an access point of a region moved when a handoff occurs while performing communication connected to an access point in a wireless data communication system using an access point. To provide a hand off method and apparatus that can reduce the time required.

A wireless communication terminal according to an embodiment of the present invention for achieving the above object is a wireless communication terminal for performing communication by connecting to an access point in a wireless data communication system, the first communication point required to access the first access point; 1. A memory unit for storing connection necessary information, and when receiving a first connection necessary information from the first access point, performing communication with the first access point using the first connection necessary information, and performing handoff while performing communication. A wireless unit for requesting at least one second connection need information necessary for connecting to each of the at least one neighboring access point using the stored first connection need information, and detecting the handoff occurrence to control the operation of the wireless unit and at least A second access point to be newly connected based on the second connection need information received from one neighboring access point Crystal and has a control unit for performing a second access point and the communications connection is determined.

Preferably, the control unit updates the second connection necessary information of the second access point determined to be connected to the first connection necessary information stored in the memory unit.

Preferably, the control unit obtains the first connection necessary information from the first access point when the wireless communication terminal is initialized and stores it in the memory unit. Thereafter, when an event requiring communication connection with the first access point occurs, the controller communicates with the first access point using the first connection necessary information stored in the memory unit.

The first connection necessary information has a form of an Address Resolution Protocol (ARP) table. The first connection necessary information includes IP information and MAC information of the first access point. The IP information includes a unique IP uniquely assigned to the first access point and a common IP commonly assigned to the first and second access points. The MAC information is BSSID (Basic Service Set Identification) information that is unique identification information of the first access point.

On the other hand, the handoff method according to an embodiment of the present invention for achieving the above object, in the handoff method of a wireless communication terminal for performing communication by accessing the access point in a wireless data communication system, the first access point Acquiring and storing the first access necessary information required for accessing the first access point from the first access point, communicating with the first access point using the first access need information, and handing off during communication. Requesting at least one second access necessary information for accessing each of the at least one neighboring access point by using the stored first access necessary information, and receiving the first access necessary information received from the at least one neighboring access point in response to the request. Determining a second access point to be newly connected based on the connection need information, and the determined second access point; Performing a communication connection with the endpoint.

Preferably, the handoff method of the present embodiment further includes updating the second connection necessary information to the stored first connection necessary information when the second access point to be newly connected is determined.

Preferably, in the storing step, a process of receiving and storing the first access necessary information from the first access point when the wireless communication terminal is initialized is performed. In the communication performing step, when an event requiring communication connection with the first access point occurs, a process of communicating with the first access point is performed using the stored first connection necessary information.

The first connection necessary information may include unique IP information uniquely assigned to the first access point, common IP information commonly assigned to the first and second access points, and BSSID (Basic identification information) of the first access point. It has an ARP (Address Resolution Protocol) table type including MAC information corresponding to service set identification (Service Set Identification) information.

According to the present invention, through the initial registration process, the wireless communication terminal and the access point respectively store the ARP table containing the IP and MAC information for each other, and if the packet transmission is necessary based on the pre-stored ARP table to communicate with each other By being able to connect, it is possible to shorten the time required to obtain the information necessary for the communication connection with each other. In addition, when a handoff occurs, a request for unique identification information (BSSID) is requested from neighboring access points to determine an access point to be newly connected based on the received field strength of the received unique identification information, and the unique identification information received from the determined access point is determined. By updating the ARP table with information, the time required to obtain ARP table information can be shortened from 300 seconds to several hundreds of milliseconds, thereby providing continuity without interruption of the communication being performed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are represented by the same numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be briefly described or omitted.

4 is a block diagram illustrating a preferred embodiment of a wireless communication terminal for more quickly processing a handoff due to a change in a communication connected access point according to the present invention.

In the present invention, the wireless communication terminal is applicable to all devices 11, 13, and 15 of the wireless communication terminal 10 shown in FIG. In the present invention, the wireless VoIP terminal 11 is described as an example among the devices 11, 13, and 15, and the features of the present invention described below are equally applicable to all other wireless communication terminals. Therefore, hereinafter, the term "wireless VoIP terminal" is used the term "wireless communication terminal" to which the present invention is equally applied to help understand the description.

As shown, the wireless communication terminal 110 includes a control unit 111, a user interface 112, a microphone 113, a speaker 114, a memory unit 115, a display unit 117, and a wireless unit 118. It is composed of

The controller 111 controls the overall operation of the wireless communication terminal 100. The user interface 112 receives a corresponding command to be used by the user and provides the command to the controller 111. The microphone 113 reads an audio signal and a voice signal and provides the same to the controller, and the speaker 114 outputs the stored audio signal and voice data received from an external network under the control of the controller 111.

The memory unit 115 stores program information necessary for the operation of the wireless communication terminal 100 and data according to the operation result. In addition, the memory unit 115 stores IP and MAC information allocated to the wireless communication terminal 100 for wireless data communication according to the present invention. In addition, according to an embodiment of the present invention, the memory unit 115 includes an ARP table 116 including IP and MAC information of the access point used to connect to the access point via the wireless LAN using the wireless unit 118. ) Is stored.

The display unit 117 displays corresponding data and operation state information of the wireless communication terminal 100 under the control of the controller 111. The wireless unit 118 performs packet communication with the access point through the wireless LAN under the control of the control unit 111.

5 is a block diagram illustrating a preferred embodiment of an access point applied for performing a quick handoff of a wireless communication terminal according to the present invention.

As illustrated, the access point 200 may include a control unit 210, a wireless unit 220, a data interface unit 230, a memory unit 240, a voice data processing unit 250, a voice interface unit 260, And a power supply unit 270.

The wireless unit 220 transmits and receives a packet through the wireless LAN with the wireless communication terminal 100 under the control of the controller 210. The wireless unit 120 outputs a packet received from the wireless communication terminal 100 to the control unit 210, and transmits a packet input from the control unit 210 to the wireless communication terminal 100.

The data interface unit 230 performs an interface function between the wired LAN 300 and the access point 200. The data interface unit 230 transmits the input data packet to the wired LAN 300, which is a data network, and outputs the data packet input from the wired LAN 300 to the controller 210.

The memory unit 240 is composed of a voice packet memory and a data packet memory. The voice packet memory and the data packet memory constituting the memory unit 240 output the input voice packet and the input data packet according to a first-in first-out method under the control of the controller 210. In addition, the memory unit 240 stores an ARP table 245 including IP and MAC information for the wireless communication terminal 100 connected to the access point 200.

The voice data processor 250 decodes the input voice packet into pulse code modulation (PCM) voice data, outputs the voice packet to the voice interface unit 260, codes the input PCM voice data into a voice packet, and echoes the received voice packet. This is removed and output to the memory unit 240.

The voice interface unit 260 interfaces with a private exchange 600 that performs a voice data switch function connected to the access point 200 to transmit and receive voice data. The voice interface unit 260 transmits the PCM voice data input from the voice data processor 250 to the private exchange 600, and outputs the PCM voice data input from the private exchange 600 to the voice data processor 250. do.

The power supply unit 270 receives power remotely from the private exchange 600 and supplies power to all functional terminals constituting the access point 200 under the control of the controller 210.

The controller 210 controls overall operations of the access point 200 and controls operations related to voice packet and data packet processing. When the packet is input from the wireless unit 220, the controller 210 first determines the type of the packet, and if the packet is a voice packet, outputs the packet to the voice packet memory, and outputs the voice packet to the voice data processor 250. Control 240. If the packet is a data packet, the controller 210 outputs the packet to the data packet memory of the memory unit 240 and controls the memory unit 240 to output the data packet to the data interface 230.

In addition, the controller 210 outputs the data packet input from the data interface 230 to the data packet memory, and controls the memory unit 240 to output the data packet to the wireless unit 220. The control unit 210 controls the memory unit 240 so that the voice packet input from the voice data processor 250 to the voice packet memory is output to the control unit 210, and the wireless unit controls the voice packet input from the memory unit 240. Output to 220.

6 is a diagram illustrating a hierarchical structure of the wireless communication terminal 110 and the access point 200 of FIG. 4 and FIG. 5 and a packet transmission path on the hierarchical layer.

As shown, the wireless communication terminal 110 includes an application layer 121, a Transmission Control Protocol / User Datagram Protocol (TCP / UDP) layer 123, an IP layer 125, and a wireless medium access control (MAC) layer. 127, the radio physical layer 129. The access point 200 includes an application layer 201, a TCP / UDP layer 202, an IP layer 203, a wireless MAC layer 204, a wireless physical layer 205, a wired MAC layer 206, a wired physical layer. 207.

The wireless communication terminal 110 configures a packet in a proper format for transmitting / receiving a packet through the application layer 121, the TCP / UDP layer 123, the IP layer 125, and the wireless MAC layer 127, and a destination IP address. Is received and transmitted to the access point 200 through the wireless physical layer 129.

The access point 200 receives the packet through the radio physical layer 205 and transmits the packet to the radio MAC layer 204, which is a higher layer. The wireless MAC layer 204 transmits to the IP layer 203 if the input packet is a voice packet. Thereafter, the voice packet is processed through the TCP / UDP layer 202 and the application layer 201 according to a corresponding process such as decoding, and then transmitted to another wired network.

The wireless MAC layer 204 transmits the input packet to the wired MAC layer 206 if the input packet is a data packet, and the wired MCA layer 206 transmits the input data packet to the wired physical layer 207. The data packet is transmitted to the data network through the wired physical layer 207.

Meanwhile, when the wireless communication terminal 110 moves from the network (wireless LAN) formed by the access point 200 currently located to the network formed by the neighboring access point, handoff occurs.

Each of the access point 200 and the wireless communication terminal 110 is assigned its own IP and MAC information which is unique identification information. The wireless communication terminal 110 obtains the IP and MAC information of the other party with the access point 200 in the area where the system is initialized and stores it as an ARP table.

FIG. 7 is a diagram illustrating an example of respective IP and MAC information allocated and interchanged to the access point 200 and the wireless communication terminal 110.

IP and MAC information 200a allocated to the access point 200 includes a unique IP, a common IP, and basic service set identification (BSSID) information. Here, the unique IP is address information used when accessing the access point 200 from the outside through the wired LAN 300. The common IP is address information used when the wireless communication terminal 110 transmits a voice packet through the wireless LAN 800. Here the common IP is equally assigned to all access points connected to the private exchange 600. The BSSID is MAC address information for unique identification of the access point 200.

The IP and MAC information 100a is allocated to the wireless communication terminal 110. IP is address information allocated to the wireless communication terminal 110 for wireless communication, and is used when the access point 200 is connected through the wireless LAN 800. The MAC information is address information for unique identification of the wireless communication terminal 110.

The wireless communication terminal 110 and the access point 200 respectively store the address resolution protocol (ARP) tables 110b and 200b composed of IP and MAC information obtained by exchanging IP and MAC information with each other during system initialization. .

That is, the access point 200 obtains an ARP table 200b composed of IP and MAC information of the wireless communication terminal 110, and the wireless communication terminal 110 recognizes the common IP and MAC information of the access point 200. An ARP table 110b composed of BSSIDs is obtained and stored. Each of the ARP tables 110b and 200b enables the wireless data communication connection between the wireless communication terminal 110 and the access point 200.

8 is a view for explaining a communication connection method with an access point during handoff according to the present invention.

When the wireless communication terminal 110 exists in the wireless LAN network area of the first access point 201, the first access point 201 uses the common IP 192.168.111.254 of the access point stored in the ARP table 110b. To communicate). At this time, the MAC (BSSID) information mapped to the common IP (192.168.111.254) of the first access point 201 in the ARP table 110b is "00: 00: F0: 00: 00: 01".

When the wireless communication terminal 110 moves from the wireless LAN network of the first access point 201 to the wireless LAN network of the second access point 203 and a handoff occurs, requesting transmission of unique identification information (BSSID) Search for neighboring access points. When each of the BSSIDs transmitted from the neighboring access points is received, the wireless communication terminal 110 determines the access point that has transmitted the BSSID having the maximum field strength as the access target access point by handoff. In the present embodiment, the second access point 203 is determined as the connection target access point.

Accordingly, the wireless communication terminal 110 obtains the BSSID (00: 00: F0: 00: 00: 02) received from the second access point 203 as MAC information corresponding to the common IP (192.168.111.254). At this time, the wireless communication terminal 110 performs the handover and displays MAC information of the ARP table for the second access point 203 having the common IP of the access point “192.168.111.254” as “00: 00: F0: 00: 00”. Update to: 02 ".

The wireless communication terminal 110 stores the ARP table for the access point and performs handoff by acquiring MAC information from neighboring access points using the common IP stored at the time of handoff and determining a connection target based on the received field strength. The time required for 3 msec to 300 msec enables fast handoff to provide seamless continuity of calls.

9 is a flowchart illustrating an initial registration process of a wireless data communication system according to a method for performing a quick handoff according to the present invention.

First, the wireless communication terminal 110 transmits a registration request signal of IP and MAC information allocated to the terminal to the access point 201 (S110). The access point 201 transmits a registration request signal of the terminal received from the wireless communication terminal 110 to the private exchange 600 (S600). The function module of the private exchange 600 according to the embodiment of the present invention may be provided as a server in the private exchange 600 separately from the access point 201 or separately from the access point 201. In the present embodiment, it will be described that the private exchange 600 is in charge of a server function in which a plurality of access points including the access point 201 are connected to perform the corresponding function of the present embodiment.

The private exchange 600 registers IP and MAC information of the terminal transmitted from the wireless communication terminal 110 via the access point 201 (S120). In response, the private exchange 600 transmits a registration response signal to the wireless communication terminal 110 via the access point 201 (S130) (S135).

When the wireless communication terminal 110 receives the response signal for the registration request of the IP and MAC information, the wireless communication terminal 110 transmits a DHCP (Dynamic Host Configuration Protocol) request signal to the private exchange 600 through the access point 201 (S140). (S145). The private exchange 600 receives the DHCP request signal from the wireless communication terminal 110 and provides a DHCP response signal to the wireless communication terminal 110 through the access point 201 to provide the common IP allocated thereto (S150). ) And transmits to the wireless communication terminal 110 (S155).

Accordingly, the wireless communication terminal 110 receives the DHCP response signal to obtain common IP information of the access point 201 included therein (S160). Meanwhile, the private exchange 600 provides the IP and MAC information on the registered wireless communication terminal 110 to the access point 201 (S170). Accordingly, the access point 201 acquires and stores IP and MAC information of the wireless communication terminal 110 (S180).

The wireless communication terminal 110 and the access point 201 store the IP and MAC information obtained for each other in an ARP table. The wireless communication terminal 110 and the access point 201 are quickly connected to each other by using the IP and MAC information already stored on the basis of the IP and MAC information obtained for each other, if the packet transmission is necessary. The necessary packet can be sent.

10 is a flowchart illustrating a preferred embodiment of a handoff method capable of providing continuity of a call by shortening a time required for performing a handoff in a wireless communication terminal according to the present invention.

First, when the voice communication data occurs (S310), the wireless communication terminal 110 retrieves common IP and MAC (BSSID) information for the first access point 201 from the ARP table (S330). The wireless communication terminal 110 communicates with the first access point 201 through the wireless LAN network based on the retrieved common IP and MAC information and transmits voice data to the first access point 201 (S350).

The first access point 201 receives voice data transmitted from the wireless communication terminal 110, transmits the voice data to the corresponding destination, and receives the data transmitted from the corresponding destination. When the IP data for transmission to the wireless communication terminal 110 is received (S370), the first access point 201 retrieves IP and MAC information of the wireless communication terminal 110 from the ARP table (S390). The first access point 201 communicates with the wireless communication terminal 110 based on the retrieved IP and MAC information of the wireless communication terminal 110 and transmits IP data to the wireless communication terminal 110 (S410).

On the other hand, when a handover condition occurs, the wireless communication terminal 110 transmits a request signal of unique identification information for each access point to each of the access points 201 and 203 connected to the private exchange 600 (S440, S445). When each of the access points 201 and 203 receives the request signal for the unique identification information from the wireless communication terminal 110, the access points 201 and 203 transmit the BSSID information indicating the unique identification information to the wireless communication terminal 110 (S450 and S455). .

Upon receiving BSSID information, which is unique identification information, from the access points 201 and 203, the wireless communication terminal 110 determines an access point to be newly connected based on the received field strength of the BSSID information (S460). In this embodiment, it is assumed that the second access point 203 is an access point to be newly connected.

Accordingly, the wireless communication terminal 110 communicates with the second access point 203 determined to be connected based on the common IP previously stored in the ARP table and the newly received BSSID information to perform packet communication (S470). At this time, the wireless communication terminal 110 updates and stores the new BSSID information in the ARP table using MAC information (S480).

In the above, specific preferred embodiments of the present invention have been illustrated and described. However, the present invention is not limited to the above-described embodiment, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention attached to the claims. will be.

According to the present invention, through the initial registration process, the wireless communication terminal and the access point respectively store the ARP table containing the IP and MAC information for each other, and if the packet transmission is necessary based on the pre-stored ARP table to communicate with each other By being able to connect, it is possible to shorten the time required to obtain information necessary for communication connection with each other.

In addition, when a handoff occurs, a request for unique identification information (BSSID) from neighboring access points is determined based on the received field strength of the received unique identification information, and the unique identification information received from the determined access point is determined. By updating the ARP table with information, the time required to obtain ARP table information can be shortened from 300 seconds to several hundreds of milliseconds, thereby providing continuity without interruption of the communication being performed.

Claims (11)

  1. A wireless communication terminal for performing communication by accessing an access point in a wireless data communication system,
    A memory unit configured to receive and store IP information and first medium access control (MAC) information of the first access point;
    The IP information and the first MAC information are received from the first access point, and when a handoff occurs to a second access point having the same IP as the first access point, the second MAC information is received from the second access point. A wireless unit for requesting handoff to the second access point;
    And a control unit controlling to receive the second MAC information of the second access point and handoff to the second access point based on the IP information stored in the memory.
  2. The method of claim 1,
    The control unit
    And updating the first MAC information stored in the memory unit to the second MAC information.
  3. The method of claim 1,
    The control unit,
    When the wireless communication terminal is initialized, the IP information and the first MAC information are acquired from the first access point and stored in the memory unit. When an event requiring communication connection with the first access point occurs, the memory unit And communicating with the first access point by using the stored IP information and the first MAC information.
  4. The method of claim 1,
    The IP information, the first MAC information and the second MAC information has a form of an ARP (Address Resolution Protocol) table.
  5. delete
  6. The method of claim 1,
    The IP information includes a unique IP uniquely assigned to the first access point and a common IP commonly assigned to the first and second access points.
  7. The method of claim 1,
    And the first MAC information is basic service set identification (BSSID) information which is unique identification information of the first access point.
  8. A handoff method of a wireless communication terminal for performing communication by accessing an access point in a wireless data communication system,
    Acquiring and storing IP information and first medium access control (MAC) information necessary for accessing a first access point from the first access point;
    Communicating with the first access point based on the stored IP information and the first MAC information;
    Requesting at least one second MAC information necessary for accessing each of at least one neighboring access point based on the stored IP information when a handoff occurs while performing the communication;
    Determining a second access point to newly connect based on the second MAC information received from at least one neighboring access point in response to the request; And
    And performing a communication connection with the determined second access point.
  9. The method of claim 8,
    And when the second access point to be accessed is determined, updating the stored first MAC information with the second MAC information.
  10. The method of claim 8,
    The storing step
    And storing the IP information, the first MAC information, and the second MAC information in the form of an Address Resolution Protocol (ARP) table.
  11. The method of claim 8,
    The IP information is a unique IP uniquely assigned to the first access point, and includes common IP information commonly assigned to the first and second access points.
    The first MAC information and the second MAC information include medium access control (MAC) information corresponding to basic service set identification (BSSID) information that is unique identification information of each of the first access point and the second access point. Hand off method characterized in that it has the form of an Address Resolution Protocol (ARP) table.
KR1020050079875A 2005-08-30 2005-08-30 Hand-off Method for performing continuously communication and Apparatus of the same KR100701039B1 (en)

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US6477156B1 (en) 1999-06-29 2002-11-05 Nokia Corporation Apparatus, and associated method, for selectably operating radio device in alternate operating mode
KR20030069312A (en) * 2002-02-19 2003-08-27 엘지전자 주식회사 Method for Providing Roaming Service due to transfer of Station in Wireless LAN
US20040023641A1 (en) 2002-03-22 2004-02-05 Takayuki Tsutsumi Telephone system
US20040043767A1 (en) 2002-08-28 2004-03-04 Nec Infrontia Corporation Fast roaming system
KR20040067419A (en) * 2003-01-23 2004-07-30 삼성전자주식회사 A handoff method in wirelessLAN

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6477156B1 (en) 1999-06-29 2002-11-05 Nokia Corporation Apparatus, and associated method, for selectably operating radio device in alternate operating mode
KR20030069312A (en) * 2002-02-19 2003-08-27 엘지전자 주식회사 Method for Providing Roaming Service due to transfer of Station in Wireless LAN
US20040023641A1 (en) 2002-03-22 2004-02-05 Takayuki Tsutsumi Telephone system
US20040043767A1 (en) 2002-08-28 2004-03-04 Nec Infrontia Corporation Fast roaming system
KR20040067419A (en) * 2003-01-23 2004-07-30 삼성전자주식회사 A handoff method in wirelessLAN

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