KR100612651B1 - Method for dynamic allocating Mobile address by Mobile IP in wireless portable internet system - Google Patents

Abstract

The present invention relates to a dynamic IP allocation method using mobile IP in a wireless portable Internet system.

The dynamic IP allocation method using mobile IP according to the present invention includes mobile IP version information in a MAC message used for registration of a subscriber station. When the mobile IP version is confirmed, the subscriber station sends a mobile IP registration request message to the base station during the MAC connection setup, and in response, the base station transmits a mobile IP registration reply message to the subscriber station to allocate a dynamic IP address to the subscriber station. . Since the dynamic IP allocation process is performed through the secondary management connection, it is possible to reduce the use of fast handoff and connection identifier. It also supports seamless services and the use of mobile IP in IEEE 802.16e wireless portable Internet systems.

IEEE 802.16e, Mobile IP, Home Agent, External Agent, Handover, MAC

Description

Method for dynamic allocating Mobile address by Mobile IP in wireless portable internet system

1 is a schematic diagram showing an outline of a wireless portable Internet system.

2 is a hierarchical diagram showing the hierarchical structure of the wireless portable Internet system.

3 is a schematic diagram illustrating a connection structure between a base station and a subscriber station device in a wireless portable Internet system.

4 is a frame diagram illustrating a frame structure of a wireless portable Internet system.

5 is a flowchart illustrating a connection establishment process in a wireless portable Internet system.

6 is a schematic diagram illustrating a prior art dynamic IP allocation system.

7 is a schematic diagram illustrating a dynamic IP allocation system according to an embodiment of the present invention.

8 is a signal flow diagram illustrating a MAC connection setup process according to an embodiment of the present invention.

9 illustrates an IP version parameter format used in an embodiment of the present invention.

10 is a signal flow diagram illustrating a handover procedure according to an embodiment of the present invention.

11 is a schematic diagram showing an IP allocation result by mobile IP according to an embodiment of the present invention.

The present invention relates to a dynamic IP address allocation method using mobile IP in a wireless portable Internet system.

More specifically, the present invention relates to a dynamic IP allocation method for providing a seamless service even in a handover situation in an IEEE 802.16e Metropolitan Area Network (MAN) system.

The wireless portable Internet is a next generation communication method that further supports mobility in a short range data communication method using a fixed access point like a conventional wireless LAN.

Various standards have been proposed for such a wireless portable Internet, and international standardization of the portable internet is currently progressing around the IEEE 802.16e.

1 is a schematic diagram showing an outline of a wireless portable Internet.

The wireless portable Internet system basically includes a subscriber station 10, base stations 20 and 21 performing wireless communication with the subscriber station, routers 30 and 31 connected through the base station and a gateway, and an internet network.

The conventional wireless LAN method such as IEEE 802.11 provides a data communication method capable of wireless communication within a short distance around a fixed access point, but IEEE 802.16 is a mobile subscriber station (hereinafter, referred to as MSS). It does not provide mobility, but has a limitation in supporting short-range data communication by wireless rather than wired.

IEEE 802.16 is basically a standard that supports metropolitan area network (MAN), and means an information communication network covering an intermediate area between a local area network (LAN) and a wide area network (WAN).

On the other hand, the wireless portable Internet system promoted by the IEEE 802.16e group or the like ensures mobility even when the subscriber station 10 shown in FIG. 1 moves from the cell managed by the base station 20 to the cell managed by the base station 21. It provides a data communication service that is not interrupted.

Accordingly, the wireless portable Internet system supports handover of the subscriber station 10 like the mobile communication service, and performs dynamic IP address allocation according to the movement of the subscriber station.

In this case, the wireless portable Internet subscriber station 10 and the base stations 20 and 21 communicate with each other by orthogonal frequency division multiple access (hereinafter, referred to as OFDMA). The OFDMA scheme is a multiplexing scheme combining a frequency division scheme using a plurality of orthogonal subcarriers as a plurality of subchannels and a time division scheme (TDM) scheme. The OFDMA scheme is inherently resistant to fading occurring in multipath, and has a high data rate.

In addition, IEEE 802.16e adopts an adaptive modulaton and coding (AMC) method in which modulation and coding schemes are adaptively selected between requesting and accepting subscriber stations 10 and base stations 20 and 21. It was.

2 is a hierarchical diagram showing the hierarchical structure of the wireless portable Internet system.

The hierarchical structure of the IEEE 802.16e wireless portable Internet system is largely divided into a physical layer (L10) and a media access control (hereinafter referred to as MAC) layer (L21, L22, L23).

The physical layer L10 is responsible for a wireless communication function performed in a normal physical layer such as modulation and demodulation and coding.

On the other hand, the wireless portable Internet system does not have a hierarchical layer for each function like a wired Internet system, and takes charge of various functions in one MAC layer.

Looking at the sub-layers by function, the MAC layer includes a privacy sub-layer (L21), a MAC common layer (L22), and a service specific set sub-layer (L23).

The service specific convergence sublayer L23 is responsible for payload header suppression and QoS mapping functions in continuous data communication.

The MAC common sublayer L22 is an essential part of the MAC layer, and is responsible for system access, bandwidth allocation, connection establishment and maintenance, and QoS management.

The privacy sublayer L21 performs device authentication, security key exchange, and encryption functions. Only authentication of the device is performed in the privacy sublayer L21, and user authentication is performed in an upper layer (not shown) of the MAC.

3 is a schematic diagram illustrating a connection structure between a base station and a subscriber station device in a wireless portable Internet system.

The MAC layer of the subscriber station MSS and the MAC layer of the base station BS have a connection relationship called a connection.

The term "connection (C1)" used in the present invention refers to a logical connection rather than a physical connection, a basic connection for the transmission of MAC control messages, two types of Management Connection, for traffic transmission by service flow There is a transport connection, and the mapping relationship between MAC peers is one primary connection, basic connection, secondary management connection and as many as the number of service flows generated between the subscriber station (MSS) and the base station (BS). It is defined as

Accordingly, the parameter or message defined on the connection C1 defines a function between MAC sibling layers, and in reality, the parameter or message is processed and framed and transmitted through the physical layer, and the frame is analyzed and the MAC layer is analyzed. It will perform the function corresponding to the parameter or message.

The connection C1 is established at initial terminal registration and is a basic connection used to transmit a delay sensitive MAC management message, and is a management connection which is not sensitive to delay and is established during initial subscriber registration. This exists. The management connection is divided into a primary management connection managing a header for lower layer work and a secondary management connection managing a header for upper layer work.

The MAC message transmitted through the connection C1 basically includes a connection identifier (hereinafter referred to as a CID) which is a MAC layer address identifying a connection; A MAP that defines a symbol offset of a burst time-divided by the subscriber station on the downlink / uplink link, a subchannel offset, a symbol number of allocated resources, and a number of subchannels; A channel descriptor (hereinafter, referred to as a downlink channel descriptor and an uplink channel descriptor referred to as DCD and UCD, respectively) describing characteristics of a physical layer according to downlink / uplink characteristics.

In addition, the MAC message includes various messages for performing a request (REQ), response (RSP), and acknowledgment (ACK) for various operations.

4 is a frame diagram illustrating a frame structure of a wireless portable Internet system.

The frame is divided into a downlink frame F1 and an uplink frame F2 according to the transmission direction. The vertical axis of the frame is a subchannel composed of orthogonal frequencies, and the horizontal axis represents a time-divisional time axis.

The downlink frame F1 includes a preamble, a downlink MAP, an uplink MAP, and a plurality of downlink bursts. The downlink bursts are not classified channels or resources by users, but are classified by transmission levels having the same modulation scheme or channel skill.

Accordingly, the downlink MAP identifies the user by using the CID, and performs resource allocation for the user with offset information, modulation scheme information, and coding information corresponding to the identified user. Therefore, the MAP has the characteristics of a broadcast channel and requires high robustness.

Meanwhile, in the case of uplink frame F2, transmission is performed for each user, and the uplink burst includes user-specific information.

5 is a flowchart illustrating a connection establishment process in a wireless portable Internet system.

When the subscriber station enters the base station (S1), the base station first establishes downlink synchronization with the subscriber station (S2). If downlink synchronization is established, the subscriber station obtains an uplink parameter in step S3. For example, the parameter may include a channel descriptor message according to characteristics of the physical layer (eg, signal-to-noise ratio).

In step S4, a ranging procedure is performed between the subscriber station and the base station. The ranging is performed by correcting and matching timing, power, and frequency information between a subscriber station and a base station. Initial ranging is performed first, and then periodically ranging is performed periodically. .

When the ranging procedure is completed, the subscriber station and the base station negotiate a basic capacity for establishing a connection (S5). When the negotiation about the basic capacity is completed, the subscriber station authentication is performed using a device identifier such as the MAC address of the subscriber station of the base station (S6).

When authentication of the subscriber station is completed and the authority to use the wireless portable Internet is confirmed, the device address of the subscriber station is registered (S8), and the IP address is provided to the subscriber station by providing an IP address from an IP address management system such as a DHCP server. Perform connection establishment (S8).

In step S9, the subscriber station receiving the IP address performs connection establishment for data transmission.

6 is a schematic diagram illustrating a prior art dynamic IP allocation system.

IEEE 802.16 supports a handover function between base stations (BS) in order to support mobility to existing fixed subscriber stations.

However, in the existing specification, the handover (also called handoff) of a user who uses a dynamic IP is not sufficiently considered, and thus, an ongoing session is disconnected when a user who uses a dynamic IP is handed over. .

As shown in FIG. 6, when the subscriber station 10 is assigned a dynamic IP address in the area of the base station 20, the subscriber station 10 requests a Dynamic Host Configuration Protocol (DHCP) of the base station 20. Done. DHCP server 50 responds to the request and assigns a dynamic IP address to the subscriber terminal. For example, if an IP address of 129.253.250.0 is assigned from a DHCP server, the subscribing terminal communicates with the end node 40 by setting the IP address during the IP lease period.

However, when the subscriber station 10 moves to the area of the base station 21 and performs handover, the DHCP server 51 allocates a new IP address. In this case, since the end node 40 does not know the new IP address of the subscriber station 10, there is a problem that the session between the subscriber station 10 and the end node 40 is lost.

In addition, when using mobile IP to support seamless service, dynamic address allocation procedure should be executed during mobile IP registration process as described in RFC3344, a mobile IP standard. However, in the current IEEE 802.16e standard, since the MAC layer connection for receiving dynamic address assignment by mobile IP is not created, this cannot be supported. Therefore, when using a dynamic IP address, wireless portable Internet users can not be provided with a seamless service, there was a problem that limits the mobility of the subscriber terminal.

The present invention provides a method for performing address assignment by mobile IP to a subscriber station for dynamic IP use in order to solve the above problems of the prior art.

In addition, the present invention provides a method for allocating a dynamic IP address that provides fast connection establishment in a wireless portable Internet system.

In addition, the present invention provides a method for allocating an address using mobile IP, which can reduce unnecessary radio resources in a wireless portable Internet system.

In order to solve the above-mentioned problems, a method for receiving a dynamic IP address by a subscriber station according to an aspect of the present invention,

a) performing initial ranging by a subscriber station entering the first base station;

b) performing authentication with the first base station;

c) sending a registration request message including a flag set to mobile IP to the first base station;

d) in response to the agent advertisement of the first base station, sending a mobile IP registration request message during MAC connection establishment;

e) receiving the mobile IP registration reply message during MAC connection establishment.

In addition, according to an aspect of the present invention, a method for assigning a dynamic IP to a subscriber station by a first base station in a wireless Internet system,

a) the first base station performing initial ranging with a subscriber station;

b) performing authentication with the subscriber station;

c) checking an IP version by receiving a registration request message including a flag set as a mobile IP;

d) receiving a mobile IP registration request message from the subscriber terminal during MAC connection establishment, corresponding to an agent advertisement;

e) sending the mobile IP registration reply message to the subscriber terminal during the MAC connection establishment.

In addition, in a wireless portable Internet system according to a feature of the present invention, a method of re-registering a mobile IP after a subscriber station moves from a first base station to a second base station,

a) performing a handover between the second base station and the subscriber station;

b) the subscriber station performing re-registration with the second base station;

c) sending a re-registration request message including a flag set to mobile IP to a second base station;

d) acquiring a care of address (COA) by the subscriber terminal in response to an agent advertisement of the second base station;

e) the subscriber station transmitting a mobile IP registration request message for the assigned IP address from the first base station during MAC connection establishment;

f) during the MAC connection establishment, the second base station relaying the mobile IP registration request message to the first base station; And

g) sending, by the first base station, a reply message to the mobile IP registration request message to the subscriber station via the second base station.

In addition, according to a feature of the present invention, a method for re-registering a mobile IP after the subscriber station from the first base station to the second base station,

a) performing a handover between the second base station and the subscriber station;

b) sending a re-registration request message including a flag set to mobile IP to a second base station;

c) determining, by the second base station, whether the first base station and the second base station have the same subset information;

d) if the first base station and the second base station have the same subset information, the second base station stops transmitting the agent advertisement to the subscriber station;

e) if the first base station and the second base station do not have the same subset information, performing the mobile IP registration through the secondary management connection;

It includes.

DETAILED DESCRIPTION Hereinafter, exemplary 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 drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification.

A dynamic IP allocation system and method according to an embodiment of the present invention will now be described in detail with reference to the drawings.

7 is a schematic diagram illustrating a dynamic IP allocation system according to an embodiment of the present invention.

The dynamic IP allocation system according to the embodiment of the present invention includes a home agent 100 and an external agent 200. The home agent is a router in the home network, which has registration information of the mobile subscriber station 10 and transmits a datagram to the current location of the end node 40 in the external network. Foreign agent (foreign agent) is a router that is connected to the network that the subscriber station is currently connected when the subscriber station 10 moves away from the home network. The home agent 100, the functions of the external agent 200 may be performed by the base station BS1 and the base station BS2, respectively, but are shown separately for convenience of description. Although not shown in FIG. 7, the wireless portable Internet system may further include an authentication authorization and accounting (AAA) server that performs authentication / billing.

The subscriber station 10 performs ranging and registration procedures in a network managed by the base station BS1 and sets and transmits a mobile IP version to be allocated to the home agent 100. The home agent 100 receives the information on the mobile IP version and transmits the mobile IP and the home agent address corresponding thereto to the subscriber station 10. The subscriber station 10 performs internet communication with the end node 40 using the mobile IP. With the mobile IP, the subscriber station has a home address and a care of address (hereinafter referred to as a COA) so that the same IP address can be used even when moving.

The subscriber station registers in the area of the base station BS1, receives an IP address and a home address from the home agent, and sets the IP address for Internet communication.

Hereinafter, the registration procedure and the IP address setting method of the subscriber station will be described in detail.

8 is a signal flow diagram illustrating a MAC connection setup process according to an embodiment of the present invention.

First, when the subscriber station enters the area of the base station BS1, an initial ranging procedure between the subscriber station and the base station BS1 is performed (S100). Initial ranging is performed through MAC message exchange as a series of procedures for information exchange and timing synchronization between subscriber stations entering the base station area.

Thereafter, an authentication procedure between the subscriber station 10 and the base station BS1 is performed (S110). The authentication procedure is not authentication of a user, but authentication of a subscriber station device, and is performed using a device address of the subscriber station.

When the subscriber station is authenticated, the registration procedure of the subscriber station is performed. At this time, a secondary management connection is established and a registration request and response (REG-REQ / RSP) procedure is performed for authentication. (S120, S130). At this time, the subscriber station 10 to receive the address assignment by the mobile IP address sets a flag for the mobile IPv4 in the IP version parameter of the registration request message (REG-REQ) to inform the base station BS1 of this fact.

The home agent of the base station BS1 transmits an Agent advertisement message, which is a mobile IP message, to the subscriber station 10 through the secondary management connection when the mobile IPv4 flag is set in the IP version parameter (S140). In an embodiment of the present invention, a mobile IPv4 flag is added in a registration request / response message of a MAC message to distinguish it from an existing DHCP message.

In the embodiment of the present invention, the flag of the IP version parameter is used to notify whether to use mobile IP, but a separate parameter is defined in the registration request / response message (REG-REQ / RSP) to notify the use of the mobile IP. You may. That is, in a subsequent step, a separate parameter indicating whether to use DHCP or mobile IP may be further included in the registration request / response message (REG-REQ / RSP) and transmitted.

The subscriber station receiving the agent advertisement message transmits a mobile IP registration request message again through the secondary management connection (S150), and when the home agent itself manages the IP address pool (Address Pool). In this case, a mobile IP message is assigned through a secondary management connection to the subscriber station 10 in a mobile IP registration reply message by assigning an IP address directly, or by assigning an IP address by connection with a DHCP server 50. Transmit (S160). The base station BS1 may include a home agent as a functional entity for the registration process of the mobile IP.

As described above, since the message about the setting and registration of the mobile IP is performed through the secondary management connection of the MAC layer, it is performed in the subscriber station registration step before the conventional transport connection step.

That is, the connection establishment time can be shortened by dynamically assigning the address to the mobile IP message transmission by the secondary management connection before setting up the transport connection for traffic transmission.

9 illustrates a format of an IP version parameter used in an embodiment of the present invention.

As described above, the mobile IP flag is set in the IP version parameter in REG-REQ / RSP, which is a MAC message transmitted between the subscriber station and the base station, in order to receive an address assignment by the mobile IP. In conventional IEEE 802.16, IPv4 301 and IPv6 302 are used as flags of IP version parameters. In the embodiment of the present invention, a flag for identifying the mobile IPv4 303 is added to bit # 3 to identify whether address allocation by mobile IP is performed in a subscriber station registration request (REG-REQ) step.

10 is a signal flow diagram illustrating a handover procedure according to an embodiment of the present invention.

As described above, the subscriber station 10 registers the IP address and the home address by using the MAC message in the secondary connection.

Thereafter, when the subscriber station 10 moves to the area controlled by the base station BS2, a handover occurs.

In the re-register process after the handover procedure, the MAC message REG-REQ / RSP required for subscriber station registration between the subscriber station 10 and the base station BS2 is exchanged (S200 and S210). When the REG-REQ / RSP message is exchanged, the MAC message includes the IP version parameter with the mobile IPv4 flag set in FIG. 9 and transmits the IP version information.

Meanwhile, the agent advertisement (Agent Advertisement) is performed by the base station BS2 through the secondary management connection (S220). The subscriber station 10 obtains a COA through the agent advertisement.

Accordingly, the subscriber station 10 transmits the mobile IP registration request message for the already assigned IP address to the new base station BS2 (S230).

The base station BS2 receiving the mobile IP registration request message recognizes the previous base station BS1 as a home agent and relays the mobile IP registration request message to the base station BS1 (S240).

The base station BS1 receiving the registration request message generates and transmits a mobile IP registration response reply message to the base station BS2 (S250).

The base station BS2 receiving the registration response reply message transmits the registration reply message to the subscriber station through the secondary management connection (S260). Through the registration procedure, the home address and the COA are bound to each other.

The base station BS1 and the base station BS2 may include a home agent and an external agent as functional entities in mobile IP processing, respectively.

By the above-described process, the base station BS1 as the home agent detects that the subscriber station is in the area of the base station BS2 and relays the data signal transmitted from the end node to the external agent. Accordingly, the subscriber station may continue to communicate with the end node using the home IP address, even after the handover.

11 is a schematic diagram showing an IP allocation result by mobile IP according to an embodiment of the present invention.

As described above, the subscriber station moved to the base station BS2 by handover has the IP address 129.1.1.10 assigned to the home agent 100, and obtains the COA 128.1.1.1 from the agent advertisement message of the external agent. do.

When the subscriber station 10 transmits a mobile IP registration request message including the home IP address information to the external agent 200 through the secondary management connection, the external agent 200 uses the network address of the home IP address. The registration request message is relayed to the home agent 100.

In response to the registration request, the home agent 100 transmits a registration reply message to the external agent 200, and the external agent 200 transmits the registration reply message to the subscriber station 10. Through the registration process, the router of the base station BS1 is registered as a home agent, and the router of the base station BS2 is registered as a foreign agent.

Accordingly, the subscriber station communicates with the end node 40 using the external agent 200, but uses the home IP address 129.1.1.10 as it is. Meanwhile, the end node 40 transmits the traffic to the home IP address 129.1.1.10, and the home agent 100 encapsulates the traffic into a COA and binds the foreign agent 200. The external agent decapsulates the traffic and transmits it to the subscriber station 10.

Since the above-mentioned request and allocation of the IP address is performed through the secondary management connection of IEEE 802.16e, even during handover, the dynamic IP allocation using the mobile IP is quickly performed to provide a seamless service.

Meanwhile, two cases may be considered when a subscriber station receiving dynamic address assignment by mobile IP moves to another base station, that is, when a handover occurs.

The first case is the movement between base stations belonging to the same subnet, and the second case is the movement between base stations belonging to different subnets. If the subnet does not change even when the user moves between base stations, mobile IP registration is not necessary. The change of the subnet information is made by sharing configuration information between base stations. The shape information is information which can be known in advance about its identifier information, IP address information and other radio parameters between neighboring base stations, and the shape information is set up in advance before the base station performs.

Here, the subnet means a network area managed by a single router above the base station.

Therefore, the dynamic address allocation method by the mobile IP according to the embodiment of the present invention should be made based on the change of the subnet.

Meanwhile, a motion detection technology exists to determine whether to re-register mobile IP when handoff. According to the movement detection technology, in a network that does not support mobility of the second layer (Layer 2), such as a wired network or a wireless LAN, the subscriber station is assumed to periodically receive an agent advertisement message and included in the agent advertisement message. It is to determine whether to re-register the mobile IP by comparing the life time and subnet information of the mobile IP to the current subscriber station.

However, in the wireless portable Internet system, the periodic transmission and reception of the agent advertisement message consumes radio resources, resulting in waste of radio resources. Therefore, an embodiment of the present invention uses an improved movement detection method that can save radio resources.

12 is a signal flow diagram illustrating a handover procedure according to another embodiment of the present invention.

When the subscriber station 10 has a handover from the base station BS1 to the base station BS2, as described above, the MAC message REG-REQ / RSP required for registration of the subscriber station between the subscriber station 10 and the base station BS2. Are exchanged (S300, S310). When the REG-REQ / RSP message is exchanged, IP version information including the mobile IPv4 flag defined in FIG. 9 is transmitted in the MAC message.

Then, in step S320, the base station BS2 determines whether the previous base station BS1 and the current base station BS2 are the same subnet. That is, in the embodiment of the present invention, movement detection is not performed by the subscriber station 10 but by the destination base station BS2 on the network.

If the base station BS2 and the base station BS1 are not in the same subnet in step S320, mobile IP registration is required, but in the same subnet, mobile IP registration is not required.

If the mobile IP registration is not necessary, the base station BS2 does not transmit the agent advertisement message to the subscriber station since it is not necessary to transmit the agent advertisement message to the subscriber station (S400). Accordingly, the terminal requests a mobile IP registration request only when receiving the agent advertisement message, and does not transmit the mobile IP registration request message when the terminal does not receive the agent advertisement message. At Layer 3 and above, communication can continue without detecting handoff.

On the other hand, when it is determined that the base station BS2 and the base station BS1 are not the same subnet, the base station BS2 transmits an agent advertisement message to the subscriber station 10 (S330). As described above, the agent advertisement is performed through the secondary management connection. The subscriber station 10 obtains a COA through the agent advertisement.

Accordingly, the subscriber station 10 transmits the mobile IP registration request message for the already assigned IP address to the new base station BS2 (S340).

The base station BS2 receiving the mobile IP registration request message recognizes the previous base station BS1 as a home agent and relays the mobile IP registration request message to the base station BS1 (S350).

Upon receiving the registration request message, the base station BS1 generates a mobile IP registration response reply message and transmits it to the base station BS2 (S360).

The base station BS2 receiving the registration response reply message transmits the registration reply message to the subscriber station through the secondary management connection (S370). Through the registration procedure, the home address and the COA are bound to each other.

That is, when the change of the subnet information occurs, according to the embodiment of the present invention described above, the mobile IP registration process is performed.

According to an embodiment of the present invention, since movement detection is performed by the network, in case of handoff between base stations in the same subnet, the agent advertisement message for inducing mobile IP registration is not transmitted. Therefore, it is possible to save radio resources according to the broadcast of the agent advertisement message transmitted to a specific terminal.

According to the above configuration, it is possible to provide a seamless service by supporting handover by mobile IP to a user who uses a dynamic address allocation method in a wireless portable Internet system of IEEE 802.16e. In addition, by using the secondary management connection when sending mobile IP messages, the time required for setting up a transport connection during handoff by mobile IP can be supported, thereby enabling faster handoff.

Further, by not additionally using a connection identifier for mobile IP, the number of additional connection identifiers used between the subscriber station and the base station can be reduced.

In addition, the network can detect the change of the subnet information, thereby saving radio resources due to unnecessary agent commercials.

Claims (16)

In the method of the subscriber station is assigned a dynamic IP address in a wireless portable Internet system, a) performing initial ranging by a subscriber station entering the first base station; b) performing authentication with the first base station; c) sending a registration request message containing mobile IP version information to be used to the first base station; d) in response to the agent advertisement of the first base station, sending a mobile IP registration request message during MAC connection establishment; e) receiving the mobile IP registration reply message during MAC connection establishment. The method of claim 1, The steps d) and e) are performed through a secondary management connection. The method of claim 2, And the mobile IP version information is a flag of an IP version parameter set to mobile IPv4. The method of claim 2, And wherein said first base station operates as a home agent. The method of claim 4, wherein The step e) further comprises the step of receiving an IP address and a home address. In a wireless portable Internet system, a method for assigning a dynamic IP to a subscriber station by a first base station, a) the first base station performing initial ranging with a subscriber station; b) performing authentication with the subscriber station; c) checking an IP version by receiving a registration request message including a flag set as a mobile IP; d) receiving a mobile IP registration request message from the subscriber terminal during MAC connection establishment, corresponding to an agent advertisement; e) sending the mobile IP registration reply message to the subscriber terminal during the MAC connection establishment. The method of claim 6, The steps d) and e) are performed through the secondary management connection. The method of claim 7, wherein The step e) further comprises the step of assigning an IP address and a home address to the subscriber station. The method of claim 8, Dynamic IP address assignment method where an IP address is assigned from a DHCP server. In the wireless portable Internet system, the subscriber station re-registers the mobile IP after the subscriber station moves from the first base station to the second base station, a) performing a handover between the second base station and the subscriber station; b) the subscriber station performing re-registration with the second base station; c) sending a re-registration request message including a flag set to mobile IP to a second base station; d) acquiring a care of address (COA) by the subscriber terminal in response to an agent advertisement of the second base station; e) sending, by the subscriber station, a mobile IP registration request message for the assigned IP address from the first base station during MAC connection establishment; f) during the MAC connection establishment, the second base station relaying the mobile IP registration request message to the first base station; g) sending, by the first base station, a reply message to the mobile IP registration request message to the subscriber station via the second base station. The method of claim 10, Step d) to g) is a mobile IP re-registration method is performed through the secondary management connection. The method of claim 11, Binding the care of address (COA) and the assigned IP address from the first base station. The method of claim 12, And the first base station is set as a home agent and the second base station is set as an external agent. In the wireless portable Internet system, a method for re-registering mobile IP after a subscriber station moves from a first base station to a second base station, a) performing a handover between the second base station and the subscriber station; b) sending a re-registration request message including a flag set to mobile IP to a second base station; c) determining, by the second base station, whether the first base station and the second base station have the same subset information; d) if the first base station and the second base station have the same subset information, the second base station stops transmitting the agent advertisement to the subscriber station; e) if the first base station and the second base station do not have the same subset information, performing the mobile IP registration through the secondary management connection; Mobile IP re-registration method comprising a. The method of claim 14, Step e), In response to an agent advertisement of a second base station, acquiring a care of address (COA) by the subscriber terminal; Transmitting, by the subscriber station, a mobile IP registration request message for the assigned IP address from the first base station during MAC connection establishment; During the MAC connection establishment, relaying, by the second base station, the mobile IP registration request message to the first base station; Transmitting, by the first base station, a reply message to the mobile IP registration request message to the subscriber station via the second base station; Mobile IP re-registration method comprising a. In the method of the subscriber station is assigned a dynamic IP address in a wireless portable Internet system, a) performing initial ranging by a subscriber station entering the first base station; b) performing authentication with the first base station; c) sending a registration request message to the first base station further including a parameter informing the use of the mobile IP; d) in response to the agent advertisement of the first base station, sending a mobile IP registration request message during MAC connection establishment; e) receiving the mobile IP registration reply message during MAC connection establishment.

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