KR100534414B1 - Apparatus and method of handoff in HPi system - Google Patents

Abstract

The present invention relates to a handoff apparatus and method for a portable internet system.

The present invention, when performing a wireless communication with the currently connected first access point while passing through the sleep mode or the shadow area is unable to communicate with the existing first access point, searching for a new second access point, handoff request Forwards the message to the packet access router via the second access point, and when the packet access router sends the received handoff request message to the first access point, the first access point is included in the received handoff request message. Verifying the terminal information and performing message authentication, and transmitting the radio channel information and authentication information allocated to the terminal to the packet access router, and then receiving the terminal from the first access point by the packet access router. Set up handoff using the wireless channel information and authentication information assigned to After the determination is completed, a handoff with the terminal is performed, so that an undelivered packet that the first access point cannot deliver to the terminal is forwarded to the second access point to be transmitted to the terminal.

Description

Apparatus and method of handoff in HPi system

The present invention relates to a handoff apparatus and method in a high speed portable internet (HPI) system, and more particularly, to a handoff apparatus and method in an HPi system that enables a terminal to perform a handoff after passing a sleep mode or a shadow area. It is about.

HPi system is a technology that uses wireless transmission technology that guarantees spectrum use efficiency in 2.3GHz frequency band, and can configure cellular network, and can effectively apply up / down asymmetric transmission characteristics of IP-based wireless data service. Has

1 is a block diagram showing the network structure of a typical HPi system.

Referring to FIG. 1, an HPi system performing wireless communication with a terminal 100 includes an access point (AP) 211 and 212 and a packet access router (PAR) 220, and an IP network 300. Connected to provide Internet services.

The IP network 300 includes a home agent (HA) 310, a foreign agent 320, and an authentication, authorization and accounting (AAA) 330, and the configuration thereof is generally well known. Is omitted.

The APs 211 and 212 perform radio channel communication by performing a wireless connection with the terminal 100, and the PAR 220 performs routing of data transmitted and received to the terminal 100 and management of the APs 211 and 212. do.

In the HPi system, the terminal 100 and the AP 211 communicate with each other by performing a wireless access procedure through an initialization process, and while the connection is established, the terminal 100 transmits the strength of the radio signal transmitted from the AP 211. Continuously detected.

When the detected strength of the wireless signal is less than or equal to the set strength, handoff is performed. The handoff process searches for the target AP 212 through active scanning and performs handoff with the found target AP 212.

In the handoff scheme, the current AP 211 instructs the target AP 212 to prepare for handoff in advance through the network, and the terminal 100 disconnects from the current AP 211 and wirelessly connects with the target AP 212. And a hard handoff method for performing the operation, and the terminal 100 maintains a wireless connection between two or more wireless channels, that is, the current AP 211 and the target AP 212, and when the handoff ends, the current AP ( 211), there is a soft handoff method.

Figure 2 shows the operation of the terminal after passing the sleep mode or shadow area in the conventional HPi system.

Referring to FIG. 2, the terminal 100 needs to maintain communication with the current AP 211 while performing the handoff of the HPi system. If the terminal 100 communicates with the current AP 211 in the sleep mode or the shadow area, If it is out of the area, communication with the AP 211 is currently impossible, so data is lost or a new wireless channel must be established through an initial connection, so that a service session cannot be maintained.

In order to solve the above problem, Korean Patent Laid-Open Publication No. 2003-61830 (method and apparatus for facilitating idle mode packet data mobile handoffs) shows a significant performance improvement effect during idle mode handoff, and the terminal has a traffic channel. We proposed a technology that can efficiently save system resources by enabling handoff without a need.

However, while the above technique can expect handoff performance during the idle mode, it cannot be applied in abnormal cases where normal handoff cannot be performed.

In order to solve the above problem, an object of the present invention is to provide a handoff apparatus and method in the HPi system that enables handoff without loss of data in the sleep mode or shadow area passing of the terminal.

A handoff device in an HPi system according to one aspect of the invention,

An apparatus for performing a handoff according to a movement of a terminal in a portable internet system, wherein the terminal is connected to a terminal to perform wireless communication, and when the terminal is in a sleep mode or in a shadowed area, temporary packets that have not been transmitted are temporarily stored. A first access point for storing; When the terminal moves in a sleep mode or in a shadowed area, the terminal newly connects with the terminal to receive a handoff message including the first access point information, performs a handoff with the terminal, and then A second access point for transmitting an undelivered packet forwarded from one access point to the terminal; And when the terminal moves in a sleep mode or in a shadowed area, receives a handoff request message of the terminal from the second access point to which the terminal newly connects, and includes the first message included in the handoff request message. By using the first access point information, the first access point to the first access point to the second access point information that is newly connected to the terminal, including a packet access router to enable packet forwarding.

A handoff method in an HPi system according to one aspect of the present invention,

A handoff method according to the movement of a terminal in a portable Internet system, the method comprising: (a) a second access point is a specific terminal (-at which time, the specific terminal enters the sleep mode or the shadow area while performing wireless communication with the currently connected first access point); Receiving a handoff request message from the terminal entering the mobile station into the communication area of the second access point and forwarding the handoff request message to the packet access router; (b) the packet access router sending the handoff request message to the first access point using the first access point information included in the received handoff request message; (c) the first access point checks the terminal information included in the handoff request message received from the packet access router, performs message authentication, and transmits the packet access to the wireless channel information and authentication information allocated to the terminal. Transmitting to the second access point via a router; (d) completing handoff setting by using the wireless channel information and authentication information allocated to the terminal received by the second access point from the first access point, and performing handoff with the terminal; And (e) forwarding undelivered packets that the first access point did not deliver to the terminal to the second access point to transmit to the terminal.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the accompanying drawings, parts irrelevant to the description of the present invention are omitted in order to clearly describe the present invention, and the same or similar parts are denoted by the same reference numerals.

3 is an operation sequence of a handoff method in an HPi system according to an aspect of the present invention.

Referring to FIG. 3, there is shown a message flow diagram between PARs 220 while the terminal 100 moves from the current AP 211 to the target AP 212, and the terminal 100 accesses the AP 211. To use the services of the HPi system through the PAR 220.

When the terminal 100 moves (S301) and leaves the current AP 211 communication area, the terminal 100 performs a handoff with the target AP 212. In this case, the terminal 100 is in the sleep mode and the current AP 211. In the case of leaving the communication area of the current AP 211 or leaving the communication area of the current AP 211 while searching for a new target AP 212 in a state in which the wireless connection with the current AP 211 is disconnected (S302). ).

The sleep mode of the terminal 100 refers to a mode in which the terminal 100 temporarily suspends the function of the terminal 100 due to power saving while the terminal 100 does not currently communicate with the AP 211 for a long time. When communication starts, the mobile station may change from the sleep mode to the normal mode to perform communication with the current AP 211.

As a result of the search in step S302, the terminal 100, which has searched for the new target AP 212, attempts a basic wireless connection to the target AP 212, and requests a handoff to the target AP 212 when there is no abnormality in the wireless connection. The message XHO-REQ is transmitted (S303). At this time, the handoff request message includes an identifier of the AP 211 that was previously serviced, a basic channel identifier (CID) allocated from the previous AP 211, and a hashed message authentication code (HMAC) tuple information.

Receiving the handoff request message, the target AP 212 adds the MAC (Media Access Control) address of the terminal 100 to the received handoff message and transmits it to the PAR 220 (XHOreq) (S304). 220 searches for an identifier of a previous AP 211 included in the received handoff request message and transmits a handoff request message to the corresponding AP 211 (XHOind; HandOff Indicate) (S305).

The AP 211 identifies the terminal 100 requesting the handoff using the MAC address and the basic CID of the terminal 100 included in the handoff request message received from the PAR 220, and uses the HMAC tuple information. Perform message authentication.

If the message authentication succeeds, the AP 211 transmits a handoff response message (XHOcnf) including the radio channel and authentication key information allocated for the terminal 100 to the PAR 220 (S306), and the PAR 220. ) Transmits the received handoff response message (XHOrsp; HandOff Response) to the AP 212 (S307).

Upon receiving the handoff response message, the target AP 212 sets up the handoff using the wireless channel and the authentication key information of the terminal 100 included in the handoff response message, and indicates that the handoff setting is successful. XHOack) is transmitted to the PAR 220 (S308).

The PAR 220 receives the handoff setup success message from the AP 212 and then notifies the AP 211 (XHOack) (S309).

In addition, since the target AP 212 has completed the setting for the handoff, it transmits a handoff response message (XHO-RSP) to the terminal 100 (S310).

The terminal 100 starts traffic communication after performing the remaining radio access procedure with the AP 212.

The previous AP 211 transmits an ACIind (Ap Context Information indicate) message to the target AP 212 through the PAR 220 to transmit data that the terminal 100 could not transmit in the sleep mode or the shadow area. In operation S311 and 312, the response is received in operation S313 and 314, and the packet that has not been delivered is forwarded to the AP 212 in operation S315. At this time, the PAR 220 updates the routing table by using the routing information for transmitting to the terminal 100 in the ACIind message received from the AP 211.

The AP 212 receiving the packet forwards the forwarded packet to the terminal 100.

Although a preferred embodiment of the present invention has been described in detail above, the present invention is not limited thereto, and various other changes and modifications are possible.

As described above, the handoff apparatus and method in the HPi system according to the present invention, when the terminal is out of the current AP communication area while in the sleep mode or shadow area, when performing the handoff with the new AP, the previous AP information By providing to the PAR to be forwarded to the packet not previously transmitted from the previous AP, there is an effect that can perform a handoff without packet loss when abnormal handoff occurs.

1 is a block diagram illustrating a general network structure of an HPi system in accordance with aspects of the present invention.

Figure 2 shows the operation of the terminal after passing the sleep mode or shadow area in the HPi system according to a feature of the present invention.

3 is an operation sequence of a handoff method in an HPi system according to an aspect of the present invention.

Claims (8)

An apparatus for performing handoff according to movement of a terminal in a portable internet system, A first access point connected to a current terminal to perform wireless communication, and temporarily storing an undelivered packet not transmitted when the terminal is in a sleep mode or a shadow area; When the terminal moves in a sleep mode or in a shadowed area, the terminal newly connects with the terminal to receive a handoff message including the first access point information, performs a handoff with the terminal, and then A second access point for transmitting an undelivered packet forwarded from one access point to the terminal; And When the terminal moves in a sleep mode or in a shadowed area, the terminal receives a handoff request message of the terminal from the second access point to which the terminal newly connects, and the first terminal included in the handoff request message. A packet access router which forwards the second access point information newly connected by the terminal to the first access point by using the access point information to enable packet forwarding. Handoff device in a mobile Internet system comprising a. The method of claim 1, The handoff request message, An identifier of the first access point, A basic channel ID assigned to the terminal by the first access point, and Hash message authentication code information of the terminal Handoff device in a mobile Internet system comprising a. In the handoff method according to the movement of the terminal in the portable Internet system, (a) The second access point is a specific terminal (wherein the specific terminal is a terminal that enters the sleep mode or the shadow area and moves to the communication area of the second access point while performing wireless communication with the currently connected first access point). Receiving and handing a handoff request message to the packet access router; (b) the packet access router sending the handoff request message to the first access point using the first access point information included in the received handoff request message; (c) the first access point checks the terminal information included in the handoff request message received from the packet access router, performs message authentication, and transmits the packet access to the wireless channel information and authentication information allocated to the terminal. Transmitting to the second access point via a router; (d) completing handoff setting by using the wireless channel information and authentication information allocated to the terminal received by the second access point from the first access point, and performing handoff with the terminal; And (e) forwarding undelivered packets that the first access point does not deliver to the terminal to the second access point to transmit to the terminal; Handoff method in a portable Internet system comprising a. The method of claim 3, wherein In the step (a), The handoff request message received from the terminal to the second access point, And an identifier of the first access point, and a basic channel ID and hash message authentication code information assigned by the terminal to the first access point. The method of claim 3, wherein In step (b), The handoff request message sent from the second access point to the packet access router is And a media access control (MAC) address of the terminal. The method of claim 3, wherein In step (d), The authentication information of the terminal, And a wireless channel information and an authentication key information assigned to the terminal by the first access point. The method of claim 3, wherein In the step (e), The first access point sending an access router context information request message to the second access point through the packet access router to receive a response; And Forwarding to the second access point an undelivered packet that the first access point failed to deliver to the terminal with the second access pointer. Handoff method in a portable Internet system comprising a. The method of claim 7, wherein And a packet access router receiving an access router context information request message from the first access point, updating a routing table for packet transmission to the terminal.