KR100463067B1 - Method for hand-off in access network of based wireless LAN - Google Patents

Abstract

According to the present invention, when a user moves to a different access point (AP) in a different network or the same network, a handset in a WLAN-based access network can reduce connection setting time between the access point and the user terminal and minimize data loss. The present invention relates to an off method, wherein an operation and a function of a WLAN define a function and an operation of a MAC layer based on an IEEE 802.11 standard, and an operation at the MAC layer may be performed by a user. When moving to AP, it reduces connection setup time between AP and user terminal, minimizes data loss, and applies technology related to macro mobility and micro mobility such as IETF Internet standard Mobile IP and Cellular IP technology for the mobility of network layer. Thus, even if the network mobility is changed to IP mobility and higher layer applications in the network layer. It provides the ability to maintain a continuous connection. In addition, the network layer provides improved mobility by applying complementary technologies based on the IETF and related technologies, in addition to the IETF specification.

Description

Method for handoff in WLAN-based access network {Method for hand-off in access network of based wireless LAN}

The present invention relates to a hand-off in a wireless LAN based access network, and more particularly, when a user moves to another access point (AP) in another network or the same network. The present invention relates to a handoff method in a WLAN-based access network that reduces connection setup time between user terminals and minimizes data loss.

In general, wireless LAN is a technology that is replaced with a wireless environment that is easy to install and move from a hub to a subscriber end when building a network.

Wireless LAN has an advantage that it is possible to build a network within a relatively faster time than wired LAN because electromagnetic waves are used from the access point equipment to the terminal equipment instead of laying the wire by wire (cable). It also has the advantage of being able to communicate on the go using laptops and PC cards without staying in a fixed desktop environment.

It is a world that wireless LAN dreams of building, building, or freely networking by members within buildings. There are various applications, and the most basic application is to build a cableless infrastructure network using a wireless LAN.

The wireless LAN is evaluated as a suitable solution for the construction of an existing network using a cable or a temporary office environment, which is inappropriate to use a cable. If a wireless LAN is installed in a university campus, a classroom, or a conference room, a wireless access environment is provided in which a laptop user can move freely and access a network. It is also connected to public networks through base stations installed in airports, train stations, and shopping centers. You can also connect your home PC and peripherals over a wireless LAN. In an industrial environment, such as assembly at a factory, automation of manufacturing processes, manufacturing plants, and large warehouses, wireless networks are often used.

1 is a diagram illustrating a general network for accessing the Internet using a WLAN.

Here, reference numeral 10 denotes the Internet, reference numeral 20 denotes a router, reference numerals 31, 32, and 33 denote an access point, and reference numeral 40 denotes a notebook terminal MN.

In this configuration, when the user terminal 40 moves out of the current WLAN AP area (eg, 31) to another AP area (eg, 33), currently transmitted data is transferred to the AP of the moved terminal. Must be conveyed to

2 is a flowchart illustrating a handoff method in a conventional WLAN-based access network.

Here, reference numeral 40 denotes a notebook MN which is a user terminal, reference numeral 31 denotes an access point currently in service, and reference numeral 33 denotes an access point to be handed off.

The user terminal notebook 40 is provided with a MAC level layer 41, which is layer 2, and an MN L3 application layer 42, which is layer 3, and the MAC level layer 31a, which is layer 2, is also provided for the access point 31 currently serving. ) And the AP L3 application layer 31b, which is layer 3, and the handoff target access point 33 also includes the MAC level layer 33a, which is layer 2, and the AP L3 application layer 33b, which is layer 3.

A conventional handoff method in a WLAN-based access network configured as described above is as follows.

First, in step S11, the notebook 40 and the access point 31 perform an initialization process, and when the initialization process is completed, a connection is established and communication is performed by a basic connection procedure (Normal Connection Setup (with Passive / Active Scan)). ).

When the connection is established, the MAC level layer 41 in the notebook 40 continuously detects the power strength in step S12, and reports it to the MAC level layer 31a of the access point 31 (Power Strength Measurement).

In step S13, the MAC level layer 31a of the access point 31 analyzes the reported power strength and determines that the handoff should be performed if it is less than or equal to the set strength, and selects the handoff target access point 33 through active scanning. Active Scanning.

Then, if the handoff target access point 33 is found, fast handoff is performed in step S14 (Fast H / O Procedure in L3), and in step S15, the existing connection is released, and then the notebook 40 and the new access point are released. (33) Re-association is performed.

After the connection is successfully established, the data communication is performed between the notebook 40 and the new access point 33 in step S16 (Data Transfer).

However, in the conventional WLAN-based access network, the handoff method releases an existing connection and establishes a new connection in order to establish a connection with another AP in the WLAN, thereby causing data loss.

That is, the conventional WLAN environment does not have a function to efficiently manage higher protocols and user profiles considering the user's mobility, as in the existing wired environment. there was.

Accordingly, the present invention has been proposed to solve various problems occurring during handoff in the conventional WLAN-based access network.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wireless LAN-based access for shortening a connection setting time between an access point and a user terminal and minimizing data loss when a user moves to a different access point (AP) in another network or the same network. To provide a handoff method in the network.

The "handoff method in a wireless LAN-based access network" according to the present invention for achieving this object,

The operation and function of the WLAN define the function and operation of the MAC layer based on the IEEE 802.11 standard, and the operation in the MAC layer is a connection setup time between the AP and the user terminal when the user moves to different APs of different networks or the same network. To shorten and minimize data loss.

Also, the technology for mobility of network layer applies macro mobility and micro mobility related technologies such as IETF Internet standard Mobile IP and Cellular IP technology. This technology provides IP mobility at the network layer and higher layer applications with the ability to maintain a persistent connection even if the network connection segment changes. It also provides the ability to minimize data loss when moving to different networks. In addition, in addition to the IETF specification suggested above, the network layer provides improved functions by applying complementary technologies based on IETF and related technologies.

The "handoff method in a wireless LAN based access network" according to the present invention for this purpose,

A notebook, which is a user terminal composed of a MAC layer and a higher level MN L3 application layer, a currently serving access point (hereinafter referred to as a "current access point") composed of a MAC layer and a higher level MN L3 application layer, and a MAC layer and a higher level. In a handoff method in a WLAN-based access network composed of a handoff target access point (hereinafter referred to as a "new access point") composed of a level MN L3 application layer,

After the initialization process, the connection is established between the notebook and the current access point.When the connection is established, the MAC layer of the notebook continuously detects the power strength and reports to the MN L3 application layer, which is higher than the MAC layer of the current access point. Steps;

If it is determined that the handoff should be performed by analyzing the power strength at the current access point, active scanning is performed to search for the handoff target access point, and if the search is performed, the MN L3 application, which is a higher level in the MAC layer of the notebook, is performed. Transmitting information about a new access point to the floor;

Requesting a connection from the MAC layer of the notebook to the MAC layer of the new access point when the connection request is delivered at the MN L3 application layer;

Reporting it to a higher level AP L3 application layer in the MAC layer of the new access point and sending a response to the access request to the MAC layer of the notebook;

At the MAC layer of the notebook, the information of the new access point is transmitted to the higher level MN L3 application layer, and the AP L3 application layer of the new access point transmits a response to the handoff to the AP L3 application layer of the current access point. Steps;

And performing a fast handoff between the notebook and the new access point after the step, and performing a reconnection setup, and then transmitting data to each other if the connection setup is successful.

In the above connection reestablishment between the notebook and the new access point, the connection is established using the information on the new access point, and when the connection is made, the connection with the current access point is characterized in that the connection is released.

In the case of a high speed handoff between the notebook and the new access point, a high speed handoff is performed by defining a new MAC message not defined in the existing WLAN standard.

1 is a general network diagram for accessing the Internet using a wireless LAN,

2 is a flowchart illustrating a handoff method in a conventional WLAN-based access network,

3 is a flowchart illustrating a handoff method in a WLAN-based access network according to the present invention.

<Explanation of symbols for the main parts of the drawings>

31 ..... Current access point

31a ..... Current AP MAC Level Layer

31b ..... Current AP L3 Application Layer

33 ..... New Access Points

33a ..... New AP MAC Level Layer

33b ..... New AP L3 Application Layer

40 ..... User terminal (notebook) (MN)

41 ..... MN MAC Level Layer

42 ..... MN L3 Application Layer

Hereinafter, described in detail with reference to the accompanying drawings, preferred embodiments of the present invention according to the technical spirit as described above.

3 is a flowchart illustrating a handoff method in a WLAN-based access network according to the present invention.

Here, reference numeral 40 denotes a notebook MN which is a user terminal, reference numeral 31 denotes an access point currently in service, and reference numeral 33 denotes an access point to be handed off.

The user terminal notebook 40 is provided with a MAC level layer 41, which is layer 2, and an MN L3 application layer 42, which is layer 3, and the MAC level layer 31a, which is layer 2, is also provided for the access point 31 currently serving. ) And the AP L3 application layer 31b, which is layer 3, and the handoff target access point 33 also includes the MAC level layer 33a, which is layer 2, and the AP L3 application layer 33b, which is layer 3.

The present invention requires a new function not defined in the existing WLAN standard in order to minimize the time for establishing a new connection. Such a function is a method of allowing a terminal (notebook) to know information of a new AP to be set up before disconnecting an existing connection for establishing a new connection.

These matters can be performed by the following methods.

1) Power measuring start command and report: A function that can determine whether handoff is needed from the current AP area to another AP area and perform the procedure in the upper layer.

2) Scanning start request and report: A function of acquiring information about a handoff target AP (new access point) and informing the upper layer of the information.

3) Re-association start command and report: A function for establishing a connection and disconnecting an existing connection using information of a new AP.

4) New MAC Message Definition: Function not defined in the existing WLAN standard, but additionally defined to reduce fast handoff and data loss.

5) Beacon (Beacon) message redefinition: A function defined in addition to the existing WLAN function in order to deliver the information of the AP and the corresponding network to the terminal for handoff with other AP and establishing a new connection.

On the other hand, even if the AP is in a different sub-network (router), the router should be able to route the sub-network. Since the current Internet network is not configured in consideration of the mobility of the user, when the user moves to another network, the Internet address must be reassigned by using the network mask and prefix of the network.

To this end, the IETF proposed that the user can continue to use the original address without any additional work at the application layer by establishing a specification that allows users to route using a new address instead of reassigning an address. Therefore, in the present invention, when the terminal (laptop) is moved to another network, the mobility of the user using the new address uses the IETF standard.

However, the connection between APs of the new network for routing after the UE (notebook) moves to the new network can minimize data loss and connection time using the functions defined above. The network layer utilizes the functions defined above as information for providing mobility of the network layer, and enables the relevant and additional information to be requested from the WLAN MAC layer.

Referring to Figure 3 attached to the process of performing a handoff when the terminal (MN: notebook) moves to another AP using these functions as follows.

First, in step S101, the notebook 40 and the access point 31 perform an initialization process, and when the initialization process is completed, a connection is established and communication is performed by a basic connection procedure (Normal Connection Setup (with Passive / Active Scan)). ).

When the connection is established, the MAC level layer 41 in the notebook 40 continuously detects the power strength in step S102, and reports it to the MAC level layer 31a of the access point 31 (Power Strength Measurement).

In addition, in step S103, the MAC level layer 41 in the notebook 40 reports the information on the power strength detection to the MN L3 application layer 42, which is a higher level (Pwr Measurement).

This allows the MN L3 application layer 42, which is a higher level, to know whether the handoff is performed.

In step S104, the MAC level layer 31a of the access point 31 analyzes the reported power level and determines that the handoff should be performed if it is less than or equal to the set power level, and determines the handoff target access point 33 through active scanning. Active Scanning.

When the search for the handoff target access point 33 ends, in step S105, the MAC level layer 41 in the notebook 40 is the handoff target access point discovered in the MN L3 application layer 42, which is a higher level. 33) will be reported (Scan Reporting).

Next, in step S106, the MN L3 application layer 42, which is the upper level, transmits a message (Probe Init.Req.) Requesting connection to the MAC level layer 41, and receives the received MAC level layer 41. ) Requests a connection to the MAC level layer 33a of the new access point 33 in step S107 (Probe Request).

The MAC level layer 33a of the new access point 33 receiving the access request notifies the AP L3 application layer 33b, which is a higher level, in step S108 (Prove Notify), and requests the connection in step S109. The MAC level layer 41 of the terminal 40 responds to the connection request (Prove Response).

Then, in step S110, the MAC level layer 41 in the notebook 40 reports that a response is received from the higher level MN L3 application layer 42 (Prove Notify), and in step S111, the new access point 33 The upper layer AP L3 application layer 33b transmits a message to perform handoff to the AP L3 application layer 31b, which is the upper level of the current access point 31 (HI initiation Req.).

After this, fast handoff is performed in step S112 (Fast H / O Procedure in L3). In this case, in order to reduce data loss during handoff, unlike the existing method, a new access point 33 is connected using the information of the new access point 33, and then the current access point 31 is disconnected from the method. Handoff is performed.

Next, in step S113, re-association is performed between the notebook 40 and the new access point 33 (Re-association). Here, the connection is re-established using the information of the new access point 33 for quick connection resetting.

Finally, in step S114, if the connection is reestablished successfully, data communication is performed between the notebook 40 and the new access point 33 (Data Transfer).

According to the invention "handoff method in the wireless LAN-based access network" described above, there is an advantage to ensure the mobility of the user and to enable a quick handoff.

In addition, there is an advantage that can be used as a technology for user and service mobility in a wireless access network in the future mobile communication network.

In addition, there is an advantage that the mobility providing technology according to the present invention can be applied to an access network using a wireless technology other than the wireless LAN.

Claims (3)

A notebook, which is a user terminal composed of a MAC layer and a higher level MN L3 application layer, a currently serving access point (hereinafter referred to as a "current access point") composed of a MAC layer and a higher level MN L3 application layer, and a MAC layer and a higher level. In a handoff method in a WLAN-based access network composed of a handoff target access point (hereinafter referred to as a "new access point") composed of a level MN L3 application layer, After the initialization process, the connection is established between the notebook and the current access point.When the connection is established, the MAC layer of the notebook continuously detects the power strength and reports to the MN L3 application layer, which is higher than the MAC layer of the current access point. Steps; If it is determined that the handoff should be performed by analyzing the power strength at the current access point, active scanning is performed to search for the handoff target access point, and if the search is performed, the MN L3 application, which is a higher level in the MAC layer of the notebook, is performed. Transmitting information about a new access point to the floor; Requesting a connection from the MAC layer of the notebook to the MAC layer of the new access point when the connection request is delivered at the MN L3 application layer; Reporting it to a higher level AP L3 application layer in the MAC layer of the new access point and sending a response to the access request to the MAC layer of the notebook; At the MAC layer of the notebook, the information of the new access point is transmitted to the higher level MN L3 application layer, and the AP L3 application layer of the new access point transmits a response to the handoff to the AP L3 application layer of the current access point. Steps; Performing a high-speed handoff between the laptop and the new access point after the step, and performing a reconnection setup and transmitting data to each other if the connection setup is successful. How to handoff from delete delete