JP2002238067A - Mobile communication system, hands-off method, and program for making computer execute the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile communication system that can effectively utilize a buffer resource. SOLUTION: In the mobile communication system provided with mobile bodies 7-k6, making wireless communication while moving and routers 6-k5 that conduct packet relay processing and store packets addressed to the mobile bodies 7-k6 by a prescribed buffer capacity, when the outer 6-k5 applies hand-off processing to the mobile body 7-k6 moved to its own wireless network, the router 6-k5 acquires service rank information of the mobile body 7-k6 and assigns the buffer of the capacity, corresponding to the service rank information to the mobile body 7-k6 to conduct storage processing. Thus, the system can assign the capacity of the buffer depending on the quality obtained by the communication service, with respect to the mobile body 7-k6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an IP (Internet).
Protocol) based mobile communication system, a handoff method in the mobile communication system, and a program for causing a computer to execute the method.
In particular, the present invention relates to a mobile communication system in which a relay device (such as a router) buffers packets addressed to a mobile, a handoff method, and a program for causing a computer to execute the method.

[0002]

2. Description of the Related Art FIG. 21 is a configuration diagram showing a schematic configuration of a conventional mobile communication system based on IP. This mobile communication system is based on the Internet (The Interne
t) and the like, a mobile body 57-1 to 57-F that implements IP and performs wireless communication while moving, and an opposite node 54 that performs communication with the mobile bodies 57-1 to 57-F.
-1 to 54-E and mobile units 57-1 to 57-F that match the network prefix of the permanent IP address (home address) held by mobile units 57-1 to 57-F.
Home network 51 and mobile bodies 57-1 to 57-
F is an external network (wireless network) 55-1 to 55-D that performs wireless communication, and a router arranged in the home network 51, and is a mobile unit 57-1 to 57-F.
Is provided in each of the external networks 55-1 to 55-D, and a home agent 52 that manages the location of the mobile units 57-1 to 57-F when the mobile unit 57-F exists in any of the external networks. Routers 56-1 to 56-D accessed by 1 to 57-F.

Here, D, E and F are arbitrary natural numbers. The mobile units 57-1 to 57-F all have the same configuration, and move between a plurality of external networks, access a router of the external network where the mobile unit is located, and connect to the IP network 53. Communication with the opponent node or another mobile. The routers 56-1 to 56-D all have the same configuration. Next, the operation of the conventional mobile communication system will be described.

FIG. 22 is an explanatory diagram for explaining a hand-off process in a conventional mobile communication system. FIG. 23 is a document "A Framework for Smooth Handovers with Mobile I".
Pv6 (work in progress) .draft-ietf-koodli-smoothv6-
00.txt ”by R. Koodli and C. Perkins (IETF (Internet
Engineering Task Force) Draft, July 2000), and the document “Buffer Management for Smooth HandOvers i
n Mobile IPv6 (work in progress) .draft-krishnamurt
hi-mobileip-buffer6-00.txt ", G. Krishnamurthi, C.
FIG. 7 is a sequence diagram showing an operation of a conventional mobile communication system disclosed in Perkins (IETF (Internet Engineering Task Force) draft, July 2000).

[0005] Here, while an arbitrary mobile unit 57-r is communicating with an arbitrary opposing node 54-o, an arbitrary external network 55-p is connected to an arbitrary external network 55-o.
q, and the access destination of the mobile unit 57-r is the router 56.
The case of switching (handing off) from -p to the router 56-q will be described as an example. Note that o is any natural number from 1 to F, and p and q are any natural numbers from 1 to D. In the handoff processing of the mobile communication system, first, the mobile 57-r is connected to the external network 55-r.
p to the external network 55-q (S10
1).

[0006] Next, the mobile unit 57-r is connected to the router 56-r.
The router advertisement (Router Advertisement: RA) message to which the smooth handoff process corresponding information by q is added is received (S102). Next, the moving body 57-r is
Binding correction (Bind) for registering the IP address assigned by the external network 55-q with the home agent 52
ing Update: BU) message and smooth handoff start (Smooth H) requesting smooth handoff processing
and over Initiate (SHIN) message to router 56
-Q (S103).

[0007] Here, the mobile unit 57-r performs buffer initialization (Buffer Initializatio) requesting buffering.
n: BI) information and a packet transfer request (Buffer Forward: BF) information for requesting the transfer of the packet stored in the router 56-p accessed before the movement.
Add to IN message. When buffering is not performed, BF information is not added. Also, the mobile unit 57-r adds buffer size information to the BI information if there is a desired buffer size.

[0008] When receiving the BU message from the mobile unit 57-r, the router 56-q transmits the BU message to the home agent 52 (S104). Also,
When receiving the SHIN message from the mobile unit 57-r, the router 56-q transmits a smooth handoff request (SHREQ) message to the router 56-p (S105). Here, when the BF information exists in the SHIN message, the router 56-q
Adds the BF information to the SHREQ message.

When the router 56-p receives the SHREQ message from the router 56-q, the router 56-p responds to the SHREQ message with a smooth handoff response (Smooth Handoff).
overReply: SHREP) message to router 56-q
(S106). Home agent 52
Upon receiving the BU message by the router 56-q, a binding response (Binding Acknowle) for the BU message is received.
dgement: BA) message is transmitted to the mobile unit 57-r via the router 56-q (S107). Router 56-q
Allocates a buffer to be used for smooth handoff to the mobile unit 57-r when BI information is present in the SHIN message received in step S103 (S108).

In steps S106 and S107, the router 56-q transmits the SHREP message and the BA
After receiving the message and allocating the buffer in step S108, the mobile unit 57-r sends a smooth handoff response (SHACK) message to the SHIN message and a BA message from the home agent 52.
(S109). Here, the router 56-q
The buffer size information for smooth handoff assigned to the mobile unit 57-r is added to the SHACK message.

The mobile unit 57-r is connected to the external network 55-
Before completing the handoff process in q, the correspondent node 54-
The packet transmitted by o to the mobile unit 57-r is transmitted to the external network 5 where the mobile unit 57-r was located before moving.
The packet arrives at the 5-p router 56-p (S110). When the router 56-p allocates a buffer for smooth handoff to the mobile 57-r, the router 56-p transmits a packet addressed to the mobile 57-r to the mobile 57-r, and transmits the packet to the mobile 57-r. The packet is stored in the buffer for smooth handoff of the mobile unit 57-r (S11).
1). The moving body 57-r has already been connected to the external network 55-
p, the router 56-p is
The packet transmitted to -r does not reach the mobile unit 57-r.

When receiving the SHREQ message to which the BF message is added from the router 56-q, the router 56-p transmits the packet stored in the buffer for smooth handoff of the mobile unit 57-r to the router 56-q. The data is transmitted to the mobile unit 57-r via the communication terminal (S112). Router 5
6-q, after completing the handoff process, the home agent 52 or the correspondent node 54-o sends the mobile unit 57
When a packet transmitted to -r is received (S113),
The data is transmitted to the mobile unit 57-r (S114), and is stored in a buffer allocated to the mobile unit 57-r in preparation for the next handoff (S115).

FIG. 24 is a flowchart showing the operation when the conventional router 56-q allocates a buffer to the mobile unit 57-r. The router 56-q is connected to the mobile unit 57-r.
First, it is determined whether or not BI information exists in the SHIN message from the mobile unit 57-r (S121). If no BI information is present in the SHIN message, the router 56-q determines that buffering is not requested, does not allocate a buffer to the mobile unit 57-r (S125), and ends the process. on the other hand,
When BI information is present in the SHIN message, the router 56-q determines whether or not buffer size information is added to the BI information and a buffer size is specified (S122).

If the buffer size is not specified, the router 56-q allocates a buffer of the default size stored in advance to the mobile unit 57-r (S127), and ends the processing. On the other hand, when the buffer size is designated, the router 56-q compares the designated size (the designated buffer size) with the previously stored maximum allocation size (S
123). If the specified size is smaller than the maximum allocation size, the router 56-q allocates a buffer of the specified size to the moving object 57-r (S124), and ends the process.
However, if the buffer resources are insufficient, a buffer having a size smaller than the designated size is allocated.
If the specified size is equal to or larger than the maximum allocation size, the router 56-
q changes the designated size to the maximum allocation size (S12).
6) Go to step S124.

[0015]

However, according to the technique described above, the router uniformly allocates a buffer to each mobile unit regardless of the difference in quality required for the communication service for each mobile unit. Excessive buffer allocation may be made for mobiles that do not require quality communication services, while insufficient buffers may be allocated for mobiles that need quality communication services. And the buffer resources cannot be used effectively.

The present invention has been made in view of the above, and provides a mobile communication system capable of effectively utilizing buffer resources, a handoff method, and a program for causing a computer to execute the method. Aim.

[0017]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, in a mobile communication system according to the present invention, a mobile unit that performs wireless communication while moving between a plurality of wireless networks, and a mobile unit that is provided for each of the wireless networks, A relay device for relaying the transmitted packet and the packet addressed to the mobile object and accumulating the packet addressed to the mobile object by a predetermined buffer amount, the relay device comprising: When performing a handoff process with the mobile unit, an obtaining unit that obtains service rank information indicating a quality required for a communication service for the mobile unit, and moving the buffer amount according to the service rank information obtained by the obtaining unit. Control means for controlling the accumulation process by allocating to the body.

According to the present invention, when the mobile unit moves into the own wireless network and performs a handoff process, the obtaining unit obtains service rank information indicating the quality required for a communication service for the mobile unit, and performs control. The means allocates a buffer amount corresponding to the service rank information acquired by the acquiring means to the moving object and controls the accumulation processing. This allows
Buffer allocation can be made according to the quality required for communication services for mobiles.

In the mobile communication system according to the next invention, the relay device has resource information obtaining means for obtaining resource information indicating the remaining buffer resources that can be allocated, and the control means includes: The buffer amount according to the resource information acquired by the resource information acquisition means is allocated to the mobile unit.

According to the present invention, the resource information obtaining means obtains resource information indicating how much buffer resources can be allocated to the relay device, and the control means obtains the resource information. Allocate a buffer amount according to the resource information to the mobile unit. As a result, the buffer can be allocated according to the service rank information and the usage status of the buffer resource.

In the mobile communication system according to the next invention, when the control means has not received a packet addressed to the mobile for a predetermined time or more after allocating the buffer amount to the mobile, The buffer amount allocated to the moving object is reduced.

According to the present invention, if the control means has not received a packet addressed to the mobile unit for a predetermined time after allocating the buffer amount to the mobile unit, the control unit reduces the buffer amount allocated to the mobile unit. By doing so, it is possible to reduce the number of buffers allocated to mobile units that have stopped receiving packets.

In the mobile communication system according to the next invention, when the control means receives a packet addressed to the mobile unit after reducing the buffer amount allocated to the mobile unit, The amount of the buffer allocated to is increased.

According to this invention, when the control unit receives a packet addressed to the mobile unit after reducing the buffer amount allocated to the mobile unit, the control unit increases the buffer amount allocated to the mobile unit. In addition, it is possible to increase the buffer allocated to the mobile unit where the packet reception is performed again.

In the handoff method according to the next invention, in the handoff method performed when a mobile unit performing wireless communication moves between a plurality of wireless networks, the mobile unit may be a router of the destination wireless network. Receiving the router advertisement message to which the smooth hand-off process correspondence information is added by the mobile terminal, and
A BU / SHIN transmitting step of transmitting to the router a binding correction message for registering the P address with the home agent of the mobile unit and a smooth handoff start message for requesting a smooth handoff process, wherein the router receives the binding correction message BU that sends the binding modification message to the home agent
Transmitting, if the router receives a smooth handoff start message, transmitting a smooth handoff request message to another router that the mobile has accessed before moving to the destination wireless network (S)
An HREQ transmitting step, an SHREP transmitting step in which the another router transmits a smooth handoff reply message to a smooth handoff request to the router, and the home agent transmits a binding response message to a binding correction message via the router to the mobile unit BA transmission step of transmitting to the mobile station, the router obtains service rank information indicating the quality required for the communication service for the mobile body, the router, the router, the service rank information obtained in the obtaining step Allocating a corresponding buffer amount to the mobile for smooth handoff processing, and the router receives a smooth handoff answer and a combined response message, allocates the buffer amount to the mobile, and then performs a smooth handoff. Answer message And transmitting the combined response message by the home agent to the mobile BA / S
A HACK transmission step, the router transmits a packet addressed to the mobile to the mobile, and a storage step of storing the packet by an amount of buffer allocated to the mobile in the allocation step; And transmitting a packet stored in the storing step to the mobile unit that has moved to the next wireless network when a smooth handoff request message is received.

According to the present invention, in the RA receiving step, the mobile unit receives the router advertisement message to which the information of the corresponding handover process by the router of the destination wireless network is added, and in the BU / SHIN transmitting step, the mobile unit. But,
In the BU transmission step, the router transmits a binding correction message for registering the IP address allocated in the destination wireless network to the home agent of the mobile unit and a smooth handoff start message for requesting a smooth handoff process. , When the binding modification message is received, the binding modification message is transmitted to the home agent, and in the SHREQ transmission step, when the router receives the smooth handoff start message, the mobile terminal moves to the destination wireless network before moving. A smooth handoff request message is transmitted to the other router that has been accessed. In the SHREP transmission step, the other router transmits a smooth handoff response message to the smooth handoff request to the router, and in the BA transmission step, the home agent connects The binding response message to modify the message to send to the mobile through the router, at the acquisition step,
The router acquires service rank information indicating the quality required for the communication service for the mobile unit, and in the allocation step, the router uses the buffer amount according to the service rank information acquired in the acquisition step for the mobile unit for smooth handoff processing. In the BA / SHACK transmission process,
After receiving the smooth handoff response and the binding response message and allocating the buffer amount to the mobile, the smooth handoff response message and the binding response message by the home agent are transmitted to the mobile, and in the accumulation process, the router performs Transmitting a packet addressed to the mobile unit, storing the packet in an amount of the buffer allocated to the mobile unit in the allocating step, and storing the packet in the packet transmitting step when the router receives the smooth handoff request message. The packet stored in step (1) is transmitted to the mobile unit that has moved to the next wireless network. As a result, a buffer can be allocated according to the quality required for the communication service for the mobile unit.

In the handoff method according to the next invention, in the BU / SHIN transmitting step, the mobile unit adds the service rank information of the mobile unit to the smooth handoff start message and transmits the message to the router. In the acquiring step, the router acquires the service rank information transmitted in the BU / SHIN transmitting step.

According to the present invention, in the BU / SHIN transmitting step, the mobile unit adds the service rank information of the mobile unit to the smooth handoff start message and transmits the message to the router. By obtaining the service rank information transmitted in the SHIN transmitting step, the service rank information can be obtained.

In the handoff method according to the next invention, in the acquiring step, the router inquires a user information server holding the service rank information as user information of the mobile unit to acquire the service rank information. It is characterized by doing.

According to the present invention, in the obtaining step, the router obtains the service rank information by inquiring of the user information server holding the service rank information as the user information of the mobile unit to obtain the service rank information. Can be.

In the handoff method according to the next invention, further, the home agent inquires of a user information server holding the service rank information as user information of the mobile unit to acquire the service rank information. In the BA transmission step, the home agent transmits the service rank information acquired in the inquiry step to the router by adding the service rank information to the binding response message, and in the acquiring step,
The router acquires the service rank information transmitted in the BA transmission step.

According to the present invention, in the inquiry step, the home agent inquires of the user information server holding the service rank information as the user information of the mobile unit to acquire the service rank information, and in the BA transmission step, the home agent transmits , Adding the service rank information obtained in the inquiry process to the binding response message and transmitting the information to the router,
In the obtaining step, the router obtains the service rank information transmitted in the BA transmitting step. Thereby, the router can acquire the service rank information.

[0033] In the handoff method according to the next invention, further, if the router has not received a packet addressed to the mobile unit for a predetermined time or more after allocating the buffer amount to the mobile unit, The method includes a reduction step of reducing the buffer amount allocated to the moving object.

According to the present invention, in the reduction step, if the router has not received a packet addressed to the mobile for a predetermined period of time after allocating the buffer to the mobile, the router allocated the buffer to the mobile. Reduce volume. As a result, it is possible to reduce the number of buffers allocated to the mobile unit that has stopped receiving packets.

[0035] In the handoff method according to the next invention, further, when the router receives the packet addressed to the mobile unit after reducing the buffer amount allocated to the mobile unit in the reduction step, The method includes an increasing step of increasing the buffer amount allocated to the moving object.

According to the present invention, in the increase step, when the router receives the packet addressed to the mobile unit after reducing the buffer amount allocated to the mobile unit in the reduction step, the router allocates the buffer allocated to the mobile unit. Increase the amount. As a result, it is possible to increase the number of buffers allocated to the mobile unit from which packet reception is performed again.

In a program according to the next invention, the operation of the method according to the invention described above can be realized by a computer. Here, the “program” is a description of a data processing method, and there is no particular limitation on the language or description method, and the program may be in any form such as a source code, a binary code, and an execution format. The “program” is not necessarily limited to a single program, but includes a program that is distributed as a plurality of modules and libraries, and a program that achieves its function in cooperation with a separate program such as an OS. .

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
This will be described in detail with reference to the drawings. The present invention is not limited by the embodiment.

Embodiment 1 FIG. 1 is a configuration diagram showing a schematic configuration of a mobile communication system based on IP according to Embodiment 1 of the present invention. This mobile communication system includes an IP network 3 such as the Internet,
7-1 to 7 that perform wireless communication while moving
-C, the opposing nodes 4-1 to 4-B that communicate with the mobiles 7-1 to 7-C, and the permanent IP addresses (home addresses) held by the mobiles 7-1 to 7-C. Home network 1 of mobiles 7-1 to 7-C that matches the network prefix, and external network (wireless network) 5-1 to perform mobile wireless communication with mobiles 7-1 to 7-C
5-A and a router arranged in the home network 1, and when the mobile units 7-1 to 7-C exist in any external network, the location management of the mobile units 7-1 to 7-C And a mobile agent 7-1 provided for each of the external networks 5-1 to 5-A.
And C-accessed routers 6-1 to 6-A.

Here, A, B and C are arbitrary natural numbers. The home network 1 includes mobile units 7-1 to 7-
The network matches the network prefix of the permanent IP address (home address) held by C. Home agent 2 is home network 1
And performs location management of the mobile units 7-1 to 7-C when the mobile units 7-1 to 7-C exist in any external network. IP network 3
Is an IP-based network such as the Internet, and includes routers 6-1 to 6-A and an opposite node 4-1.
... 4-B and the home agent 2.

The opposing nodes 4-1 to 4-B are information devices such as PCs (personal computers), and are connected to the IP network 3 and communicate with the mobile units 7-1 to 7-C. The external networks 5-1 to 5-A are mobile units 7
-1 to 7-C are connected to an antenna (not shown) which forms an area where wireless communication is possible. Moving object 7-1 to 7-C
Are information devices such as portable information devices and vehicle-mounted information devices, all having the same configuration. The moving bodies 7-1 to 7-C are:
While moving between a plurality of external networks, it accesses a router of the external network where the mobile unit is located, and performs communication with any of the opposing nodes 4-1 to 4-B or another mobile unit.

The routers 6-1 to 6-A have the same configuration, are provided for each of the external networks 5-1 to 5-A, and are accessed by the mobile units 7-1 to 7-C.
FIG. 2 is a functional configuration diagram showing a functional configuration of the router 6-1 shown in FIG. The router 6-1 is connected to the IP network 3
An interface (I / F) unit 11 for communicating with the
A control unit 12 for controlling transmission / reception of packets, a storage unit 13 for storing data, a service rank acquisition unit 14 for acquiring service rank information of a moving body that has moved into its own external network, and an assignable buffer resource A resource information acquisition unit 15 for acquiring resource information indicating how much remains in the storage unit 13; and a buffer area 16 provided in the storage unit 13 for buffering packets addressed to each mobile unit in the external network. -1 to 1
6-g, and an I / F unit 17 for performing communication with the mobile unit. Note that g is the number of mobile units in the external network.

Here, the service rank information indicates the quality required for a communication service for a mobile unit, and is indicated by a level such as “high”, “medium”, “low” or a numerical value. Can be compared. The I / F unit 11
The communication with the IP network 3 is performed. The control unit 12 controls transmission and reception of packets and, when the mobile unit moves to its own external network, a buffer area (hereinafter, referred to as a buffer size) of a buffer amount (buffer size) according to the resource information and the service rank information of the mobile unit. (May be simply referred to as a buffer). Storage unit 13
Has a recording medium such as a hard disk and stores data. The service rank obtaining unit 14 obtains service rank information of a mobile that has moved into its own external network.

The resource information acquisition unit 15 obtains resource information indicating how much buffer resources can be allocated remaining in the storage unit 13, that is, how much buffer amount (buffer size) can be allocated. get. The buffer areas 16-1 to 16-g are allocated to each mobile unit in the external network, and buffer packets addressed to each mobile unit. The I / F unit 17 performs communication with a mobile unit. In addition,
Other routers 6-1 to 6-A have the same configuration.

Next, the operation of the first embodiment will be described with reference to FIG.
This will be described with reference to FIGS. FIG. 3 is an explanatory diagram illustrating an operation of the mobile communication system according to the first embodiment. FIG. 4 is a sequence diagram illustrating an operation of the mobile communication system according to the first embodiment. Here, an arbitrary mobile unit 7-1 moves from an arbitrary external network 5-j to an arbitrary external network 5-k while performing communication with an arbitrary opposite node 4-i, and communicates with the arbitrary mobile node 7-l. The case where the access destination is switched from the router 6-j to the router 6-k (handoff) will be described as an example. Note that i is 1 to
B is any natural number, and j and k are any natural numbers from 1 to A.

In the handoff process of the mobile communication system, first, the mobile unit 7-1 moves from the external network 5-j to the external network 5-k (S1). Next, the mobile unit 7-1 transmits a router advertisement (Router A) to which the information for supporting the smooth handoff process by the router 6-k is added.
dvertisement: RA) message is received (S2).
Next, the mobile unit 7-1 registers a binding update (BU) message for registering the IP address allocated in the external network 5-k with the home agent 2,
And a smooth handoff start (Smooth Handover Initiate: SHIN) message requesting a smooth handoff process is transmitted to the router 6-k (S3).

Here, the mobile unit 7-1 performs buffer initialization (BufferInitialization: B) for requesting buffering.
I) Information, packet transfer request (Buffer Forward: BF) information for requesting the transfer of the packet stored in the router 6-j accessed before the movement, and service rank information of the own mobile unit are added to the SHIN message. I do. When buffering is not performed, BF information is not added. In addition, the mobile unit 7-1 adds buffer size information to the BI information if there is a desired buffer size.

The control unit 12 of the router 6-k includes the mobile unit 7-
1 receives the BU message, the control to transmit the BU message to the home agent 2 is performed (S
4). In addition, the control unit 12 of the router 6-k controls the mobile unit 7-k.
1 receives the SHIN message from the router 6
j to Smooth Handover Reques
t: SHREQ) message is transmitted (S
5). Here, when the BF information exists in the SHIN message, the control unit 12 of the router 6-k adds the BF information to the SHREQ message. Also, the router 6-k
The service rank acquisition unit 14 acquires the service rank information added to the SHIN message (S6).

[0049] The router 6-j receives the SH by the router 6-k.
When the REQ message is received, a smooth handoff reply (Smooth Handover) for the SHREQ message is received.
Reply: SHREP) message is returned to the router 6-k (S7). Home agent 2 is router 6-k
Received a BU message by the BU, the binding response to the BU message (Binding Acknowledgement: B
A) The message is transmitted to the mobile unit 7-1 via the router 6-k (S8). When the SHIN message received in step S3 includes the BI information, the control unit 12 of the router 6-k allocates a smooth handoff buffer having a buffer size corresponding to the service rank information to the mobile unit 7-1 (S9). .

The control unit 12 of the router 6-k determines in step S
7 and in step S8 the SHREP message and B
After receiving the A message and allocating a buffer in step S9, a smooth handoff response (SHACK) message for the SHIN message and a BA message from the home agent 2 are transmitted to the mobile unit 7-1 (S10). Here, the control unit 12 of the router 6-k
Adds the buffer size information for smooth handoff assigned to the mobile unit 7-1 to the SHACK message.

The packet transmitted from the correspondent node 4-i to the mobile unit 7-l before the mobile unit 7-l completes the handoff process in the external network 5-k is transmitted to the mobile unit 7-l.
Arrives at the router 6-j of the external network 5-j located before the movement (S11). When the router 6-j allocates a buffer for smooth handoff to the mobile unit 7-1, the control unit 12 of the router 6-j sends the mobile unit 7-1
A packet addressed to the mobile unit 7-1 is transmitted to the mobile unit 7-1, and the packet is stored in a buffer for smooth handoff of the mobile unit 7-1 (S12). That is, the packets addressed to the mobile unit 7-1 are accumulated by the buffer size allocated by the FIFO (first in first out) method.

The mobile unit 7-1 has already been connected to the external network 5.
-J, the router 6-j moves to the mobile 7-
The packet transmitted to 1 does not reach the mobile unit 7-1. When receiving the SHREQ message to which the BF message is added from the router 6-k, the control unit 12 of the router 6-j transfers the packet stored in the buffer for smooth handoff of the mobile unit 7-1 to the router 6-k. (S13). After completing the handoff process, the control unit 12 of the router 6-k receives a packet transmitted from the home agent 2 or the correspondent node 4-i to the mobile unit 7-1 (S1).
4) Send to the mobile unit 7-1 (S15) and perform control to save the data in the buffer allocated to the mobile unit 7-1 in preparation for the next handoff (S16).

FIG. 5 shows a router 6 according to the first embodiment.
12 is a flowchart illustrating an operation when k allocates a buffer to the moving object 7-1. Control unit 12 of router 6-k
When assigning a buffer to the mobile unit 7-1, first,
It is determined whether or not BI information exists in the SHIN message from the mobile unit 7-1 (S21). If no BI information is present in the SHIN message, the control unit 12 determines that buffering is not requested, does not allocate a buffer to the mobile unit 7-1 (S26), and ends the process.

On the other hand, when BI information exists in the SHIN message, the control unit 12 determines whether or not buffer size information is added to the BI information and a buffer size is designated (S22). When the buffer size is designated, the control unit 12 compares the designated size (designated buffer size) with the previously allocated maximum size (S23). When the designated size is smaller than the maximum allocation size, the resource information acquisition unit 15 acquires resource information by subtracting the allocated buffer size from the size of the entire allocation buffer resource. Control unit 12
Determines whether the buffer resources are in a shortage state based on the resource information (S24).

When the buffer resources are in a shortage state,
The control unit 12 performs a buffer allocation process of allocating a buffer size according to the service rank information (S25),
The process ends. On the other hand, if the buffer resources are not in the shortage state, the control unit 12 allocates a buffer of the designated size to the mobile unit 7-1 (S <b> 28), and ends the processing. If the specified size is equal to or larger than the maximum allocation size in step S23, the control unit 12 changes the specified size to the maximum allocation size (S27), and proceeds to step S24.

If no buffer size is specified in step S22, the resource information acquisition unit 15 acquires resource information by subtracting the allocated buffer size from the size of the entire buffer resource for allocation. The control unit 12 determines whether the buffer resources are in a shortage state based on the resource information (S29). When the buffer resource is in a shortage state, the control unit 12 sets the default size stored in advance as the designated size (S3).
0), and proceed to step S25. On the other hand, if the buffer resources are not in a shortage state, the control unit 12 allocates a buffer of the default size to the mobile unit 7-1 (S31).
The process ends.

FIG. 6 shows a router 6 according to the first embodiment.
It is a flowchart which shows the processing procedure of buffer allocation processing of k (processing of step S25). In this case, the service rank information includes three values of “high”, “medium” and “low”.
The case of the stage will be described as an example. In this buffer allocation process, the control unit 12 of the router 6-k first determines whether or not the service rank information of the mobile unit 7-1 is "high" (S41).

If the service rank information of the mobile unit 7-1 is not “high”, the control unit 12 determines whether the service rank information is “medium” (S 42). If the service rank information is not “medium”, the control unit 12 determines that the service rank information is “low”, does not allocate a buffer to the mobile unit 7-1 (S 43), and ends the buffer allocation process. If the service rank information is “high” in step S41, the control unit 12 compares the designated size with the resource information and determines whether the designated size can be allocated (S45).

If it is not possible to allocate the specified size, that is, if there is not enough buffer resource remaining in the storage unit 13 to allocate the specified size, the control unit 12 has already allocated the service rank information to the mobile unit with a low value. The number of buffers used is reduced, and an area for the designated size is secured (S46). Then, the control unit 12 allocates a buffer for the mobile unit 7-1 to the secured area (S47), and ends the processing. On the other hand, if it is determined in step S45 that the designated size can be allocated, the process proceeds to step S47. If the service rank information is “medium” in step S42, the control unit 12 compares the designated size with the resource information and determines whether the designated size can be allocated (S4).
4).

If it is not possible to allocate the specified size, that is, if there is not enough buffer resource left in the storage unit 13 to allocate the specified size, step S43 is executed.
If the designated size can be assigned, the process proceeds to step S47. The method of allocating the buffer is not limited to the methods shown in FIGS. 5 and 6, and the buffer size may be determined using, for example, a predetermined formula or table based on the service rank information and the resource information. Further, the service rank information may have two or four or more levels, or may be a stepless number represented by a real number.

According to the first embodiment, service rank acquiring section 14 establishes mobile unit 7-1 in its own external network.
Moves and performs the handoff process, obtains the service rank information of the mobile unit 7-1, and the control unit 12 allocates a buffer of a buffer size corresponding to the service rank information to the mobile unit 7-1 and stores the buffer. Control processing. As a result, the buffer can be allocated according to the quality required for the communication service for the mobile unit 7-1.
Buffer resources can be effectively used.

Embodiment 2 Embodiment 2 of the present invention
In the first embodiment, the router that performs the smooth handoff process acquires the service rank information of the mobile unit from the user information server in the first embodiment. FIG. 7 is a configuration diagram illustrating a schematic configuration of the mobile communication system according to the second embodiment of the present invention. The same components as in the first embodiment are denoted by the same reference numerals as those in FIG. This mobile communication system is different from the mobile communication system of the first embodiment in further including a user information server 21 and adding service rank information to the SHIN message instead of the mobiles 7-1 to 7-C. Routers 6-1 to 6-A,
And routers 22-1 to 22-A that acquire service rank information of mobile units from the user information server 21.

The user information server 21 is connected to the IP network 3 and, as user information, each of the mobile units 23-1 to 23-1
23-C service rank information is held. The user information server 21 may be provided in the home network 1 or may be provided outside the home network 1. Moving object 2
3-1 to 23-C are the moving bodies 7-1 to 7 of the first embodiment.
-C has the same configuration and operates similarly, but does not add service rank information to the SHIN message. The routers 22-1 to 22-A all have the same configuration.

FIG. 8 is a functional configuration diagram showing a functional configuration of the router 22-1 shown in FIG. The same components as those in the first embodiment are denoted by the same reference numerals as those in FIG. The router 22-1 has the same configuration as the router 6-1 of the first embodiment and operates in the same manner, but the control unit 24 is different. The control unit 24 includes, in the control unit 12 of the first embodiment, a service rank obtaining unit 25 that obtains service rank information of a mobile unit from the user information server 21 instead of the mobile unit instead of the service rank obtaining unit 14. .
The service rank obtaining unit 25 has the same configuration as the service rank obtaining unit 14 of the first embodiment and operates in the same manner, but obtains the service rank information of the mobile unit from the user information server 21 instead of the mobile unit. .

Next, the operation of the second embodiment will be described with reference to FIG.
This will be described with reference to FIG. FIG. 9 is an explanatory diagram illustrating the operation of the mobile communication system according to the second embodiment. FIG. 10 is a sequence diagram illustrating the operation of the mobile communication system according to the second embodiment. Here, an arbitrary mobile unit 23-1 moves from an arbitrary external network 5-j to an arbitrary external network 5-k while communicating with an arbitrary opposite node 4-i, and The case where the access destination is switched from the router 22-j to the router 22-k will be described as an example. The same operations as in the first embodiment are denoted by the same reference numerals as in FIG.

In the handoff process of the mobile communication system, in the handoff process of the first embodiment, instead of step S3, the mobile unit 23-1 transmits the SHIN message and the BU message without the service rank information to the router 22. Perform step S51 of transmitting to -k,
Instead of step S6, the service rank obtaining unit 25 of the router 22-k executes step S52 of inquiring of the user information server 21 to obtain the service rank information of the mobile unit 23-1. In step S51, the mobile unit 23-
1 adds BI information and BF information to the SHIN message. When buffering is not performed, B
No F information is added. Also, the mobile unit 23-1 transmits the buffer size information to B if there is a desired buffer size.
Add to I information. Other operations are the same as those in the first embodiment.

According to the second embodiment, the service rank obtaining unit 25 stores the mobile unit 23-1 in the user information server 21.
When the service rank information is inquired, the same effect as in the first embodiment can be obtained.

Embodiment 3 Embodiment 3 of the present invention
In the second embodiment described above, the home agent inquires and obtains service rank information from the user information server, adds the service rank information to the BA message, and transmits the BA message to the access destination router of the mobile unit. The router acquires the service rank information added to the BA message.

FIG. 11 is a configuration diagram showing a schematic configuration of a mobile communication system according to the third embodiment of the present invention.
The same components as those in the second embodiment are denoted by the same reference numerals as those in FIG. This mobile communication system
In the mobile communication system according to the second embodiment, the service rank information of the mobile unit is obtained from the user information server 21 instead of the home agent 2, and the service rank information is added to the BA message to determine the access destination of the mobile unit. A home agent 31 for transmitting to a router is provided. Instead of the routers 22-1 to 22-A, the routers 32-1 to 32-3 acquire service rank information added to the BA message.
32-A. The routers 32-1 to 32-A all have the same configuration.

FIG. 12 shows the router 32-1 shown in FIG.
FIG. 3 is a functional configuration diagram showing a functional configuration of the first embodiment. The same components as those in the second embodiment are denoted by the same reference numerals as those in FIG. The router 32-1 is the router 22 of the second embodiment.
-1 has the same configuration and operates in the same manner.
3 is different. The control unit 33 includes the control unit 24 according to the second embodiment.
Includes a service rank obtaining unit 34 for obtaining service rank information added to the BA message, instead of the service rank obtaining unit 25. The service rank acquisition unit 34 has the same configuration as the service rank acquisition unit 25 of the second embodiment and operates in the same manner, but acquires the service rank information added to the BA message by the home agent 31.

Next, the operation of the third embodiment will be described with reference to FIG.
3 and FIG. FIG. 13 is an explanatory diagram illustrating the operation of the mobile communication system according to the third embodiment. FIG. 14 is a sequence diagram illustrating the operation of the mobile communication system according to the third embodiment. Here, an arbitrary mobile unit 23-1 moves from an arbitrary external network 5-j to an arbitrary external network 5-k while performing communication with an arbitrary opposing node 4-i.
The case where the access destination of 1 is switched from the router 32-j to the router 32-k will be described as an example. The same operation as in the second embodiment is denoted by the same reference numeral as in FIG.

In the handoff process of the mobile communication system, the home agent 31 which has received the BU message from the router 32-k in the handoff process of the second embodiment inquires of the user information server 21 and further checks the mobile device 23-k. Step S61 of acquiring the service rank information of l is performed, and instead of step S8, the home agent 31 adds the service rank information acquired in step S61 to the BA message,
The BA message is transmitted to the mobile unit 23 via the router 32-k.
Step S62 of transmitting to −l is executed, and Step S5
2 instead of the service rank acquisition unit 3 of the router 32-k
4 executes step S63 of acquiring service rank information from the BA message transmitted in step S62. Other operations are the same as in the second embodiment.

According to the third embodiment, the same effect as in the second embodiment can be obtained when the home agent 31 inquires the user information server 21 of the service rank information of the mobile unit 23-1.

Embodiment 4 Embodiment 4 of the present invention
In the first to third embodiments described above, after the router performing the smooth handoff process allocates a buffer to the mobile, the router increases or decreases the allocated buffer size according to the arrival status of the packet addressed to the mobile. It is intended to be. Hereinafter, an example in which this embodiment is applied to the mobile communication system of the first embodiment will be described. However, the present embodiment can be similarly applied to the mobile communication systems of the second and third embodiments.

FIG. 15 is a configuration diagram showing a schematic configuration of a mobile communication system according to the fourth embodiment of the present invention.
The same components as in the first embodiment are denoted by the same reference numerals as those in FIG. This mobile communication system
In the mobile communication system according to the first embodiment, the router 6
Instead of -1 to 6-A, if no packet addressed to the mobile unit arrives for a predetermined time after allocating a buffer to the mobile unit, the allocated buffer size is reduced. When a packet addressed to the router 4 arrives, it reviews the buffer size.
1-1 to 41-A. Routers 41-1 to 41-A
Have the same configuration.

FIG. 16 shows the router 41-1 shown in FIG.
FIG. 3 is a functional configuration diagram showing a functional configuration of the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals as those in FIG. The router 41-1 is a router 6-1 of the first embodiment.
1, after allocating a buffer to a mobile unit in place of the control unit 12, if a packet addressed to the mobile unit does not arrive for a predetermined time, the allocated buffer size is reduced;
Further, a control unit 42 is provided for revising the buffer size when a packet addressed to the mobile arrives after the buffer size is reduced.

The control unit 42 is the same as the control unit 12 of the first embodiment.
And operates in the same way, but instead of keeping the buffer as it is until the validity period of the buffer expires, after allocating the buffer to the mobile, packets addressed to the mobile for a predetermined time are If the packet does not arrive, the allocated buffer size is reduced, and when the packet addressed to the mobile arrives after the buffer size is reduced,
Increase its buffer size.

Next, the operation of the fourth embodiment will be described with reference to FIG.
This will be described with reference to FIGS. FIG. 17 is an explanatory diagram illustrating the operation of the mobile communication system according to the fourth embodiment. FIG. 18 is a sequence diagram illustrating the operation of the mobile communication system according to the fourth embodiment. Here, a case will be described as an example where an arbitrary mobile unit 7-1 accesses the router 41-k of an arbitrary external network 5-k and communicates with an arbitrary opposite node 4-i. The same operations as in the first embodiment are denoted by the same reference numerals as in FIG.

In the operation of the mobile communication system, when the mobile unit 7-1 completes the handoff process for the router 41-k, the control unit 42 of the router 41-k moves from the home agent 2 or the correspondent node 4-i. When packets transmitted to the mobile unit 7-1 are received (S14), the packets are transmitted to the mobile unit 7-1 (S1).
5) In preparation for the next handoff of the mobile unit 7-1, the packets are stored in the buffer allocated to the mobile unit 7-1 (S16).

Thereafter, if a packet addressed to the mobile unit 7-1 does not arrive for a predetermined time or more, the router 41
The -k control unit 42 reduces the buffer size of the buffer allocated to the moving object 7-1 (S71). After the buffer size is reduced, when the packet addressed to the mobile unit 7-1 arrives again (S72), the control unit 42 of the router 41-k reviews the buffer size for the mobile unit 7-1 (S7).
3). Then, the control unit 42 of the router 41-k transmits the arriving packet to the mobile unit 7-l and (S
74), and accumulates the packet in the buffer (S7).
5). Thereafter, if a packet addressed to the mobile unit 7-1 does not arrive for a predetermined time or more, the above-described operation is repeated.

FIG. 19 shows the configuration of the router 4 according to the fourth embodiment.
1-k allocation buffer size reduction processing (step S7)
2 is a flowchart illustrating a processing procedure of (1). In the buffer size reduction processing, the buffer size is reduced based on the service rank information of the mobile unit 7-1.
The buffer size may be reduced based on the service rank information and the resource information.

In this buffer size reduction processing, first,
The control unit 42 of the router 41-k determines whether the service rank information of the mobile unit 7-1 is “high” (S8).
1). When the service rank information is not “high”, that is, when the service rank information is “low” or “medium”, the control unit 42 releases and eliminates the buffer for the moving object 7-1 (S <b> 82), and The reduction processing ends. On the other hand, when the service rank information is “high”, the control unit 4
No. 2 terminates the buffer size reduction process without changing the buffer size for the moving object 7-1.

FIG. 20 shows a router 4 according to the fourth embodiment.
1-k allocation buffer size review processing (step S
73 is a flowchart showing a processing procedure of (processing 73).
In the allocated buffer size review process, first, the control unit 42 of the router 41-k determines whether the service rank information of the mobile unit 7-1 is “high” (S91).
Then, when the service rank information is “high”, the control unit 42 ends the allocation buffer size review processing as it is. On the other hand, when the service rank information is not “high”, that is, when the service rank information is “low” or “medium”, the control unit 42 determines whether the buffer resources are in a shortage state (S92).

In step S92, the control unit 42
For example, referring to the resource information, it is determined whether or not the buffer resource is in a shortage state based on whether or not the unallocated buffer resource has a size equal to or smaller than a predetermined value set in advance. If the buffer resources are not in shortage,
The control unit 42 allocates the buffer size allocated before the reduction by the above-described buffer size reduction processing (S95). That is, when the buffer size is specified from the mobile unit 7-1, the specified size is assigned,
If the buffer size is not specified from the mobile unit 7-1, a default size is assigned.

On the other hand, when the buffer resources are in a shortage state, the control unit 42 determines whether or not the service rank information of the mobile unit 7-1 is “medium” (S 93). When the service rank information is not “medium”, that is, when the service rank information is “low”, the control unit 42 does not allocate a buffer to the moving object 7-1 (S <b> 96) and ends the allocated buffer size review processing. On the other hand, when the service rank information is “medium”, if the allocation is possible, the control unit 42 allocates the buffer size allocated before the reduction by the above-described buffer size reduction processing (S9).
4).

That is, when the buffer size is specified from the mobile unit 7-1, the specified size is allocated, and when the buffer size is not specified from the mobile unit 7-1, the default size is allocated. If allocation is not possible, no buffer is allocated to the mobile unit 7-1, and the allocated buffer size review processing ends. Note that the buffer size reduction processing and the buffer size review processing are described in FIG.
The method is not limited to the method shown in FIG. 20 and the buffer size may be determined using a predetermined formula or table based on service rank information and resource information, for example. Further, the service rank information may have two or four or more levels, or may be a stepless number represented by a real number.

According to the fourth embodiment, control unit 42
However, after allocating a buffer to the mobile 7-1, if a packet addressed to the mobile 7-1 has not been received for a predetermined time or more, the buffer size of the buffer allocated to the mobile 7-1 is reduced, When a packet addressed to the mobile unit 7-1 is received, the buffer size for the mobile unit 7-1 is increased. As a result, the buffer allocated to the mobile unit 7-1 in which packet reception is no longer performed can be reduced, the deleted portion can be allocated to another mobile unit, and when packet reception is performed again, Since the number of buffers can be increased, buffer resources can be more effectively utilized.

The components of the router according to the first to fourth embodiments are functionally conceptual, and need not necessarily be physically configured as illustrated. For example, all or a part of the processing functions of these routers may be replaced by a CPU (Central
Processing Unit) and a program interpreted and executed by the CPU. That is, an OS (Operating System) is stored in a ROM (not shown).
A computer program is provided which gives instructions to the CPU in cooperation with the above, and causes the CPU to perform various processes. Then, the CPU performs various processes according to the program. Further, all or a part of the processing functions of these routers can be implemented as hardware by wired logic.

Further, a computer program for realizing the handoff method according to the first to fourth embodiments may be implemented by a magnetic disk such as a floppy (registered trademark) disk, or a semiconductor memory such as a ROM, an EPROM, an EEPROM, or a flash ROM. (Including those built into cartridges, PC cards, etc.), CD-ROM, DV
D, an optical disk such as an MO, a magneto-optical disk such as an MO, or the like, and stored in a portable recording medium. By installing it on a fixed recording medium, the router, mobile unit, and home agent can be provided with the functions described above.

Further, this program is transferred to LAN, WA
N, via a network such as the Internet,
The transmitted program may be installed in a fixed recording medium of the router, the mobile unit, and the home agent. Further, this program is not necessarily limited to a single program, and may be distributed as a plurality of modules or libraries, or may achieve its function in cooperation with a separate program such as an OS. It may be.

[0091]

As described above, according to the present invention, when the mobile unit moves within the own radio network and performs the handoff process, the acquisition unit provides the service indicating the quality required for the communication service for the mobile unit. The rank information is acquired, and the control means controls the accumulation process by allocating a buffer amount corresponding to the service rank information acquired by the acquisition means to the moving object. As a result, the buffer can be allocated according to the quality required for the communication service for the mobile unit, so that the buffer resources can be effectively used.

[0092] According to the next invention, the resource information acquisition means acquires resource information indicating how much buffer resources that can be allocated remain in the relay device.
The control means allocates a buffer amount corresponding to the resource information obtained by the resource information obtaining means to the moving object. As a result, the buffer can be allocated in accordance with the service rank information and the use status of the buffer resource, so that the buffer resource can be more effectively utilized.

According to the next invention, after the control means allocates the buffer amount to the mobile unit, if the control unit does not receive the packet addressed to the mobile unit for a predetermined time or more, the control unit determines the buffer amount allocated to the mobile unit. By reducing the number of buffers, it is possible to reduce the number of buffers allocated to the mobile unit from which packet reception is no longer performed, so that buffer resources can be used more effectively.

[0094] According to the next invention, when the control unit receives a packet addressed to the mobile unit after reducing the buffer amount allocated to the mobile unit, the control unit increases the buffer amount allocated to the mobile unit. Accordingly, it is possible to increase the number of buffers allocated to the mobile unit from which packet reception is performed again, so that buffer resources can be more effectively utilized.

According to the next invention, in the RA receiving step, the mobile unit receives the router advertisement message to which the information of the correspondence of the smooth handoff processing by the router of the destination wireless network is added, and in the BU / SHIN transmitting step, the mobile unit moves. The mobile station transmits to the router a binding correction message for registering the IP address allocated in the destination wireless network with the home agent of the mobile station, and a smooth handoff start message for requesting a smooth handoff process. , When the router receives the binding modification message, the router transmits the binding modification message to the home agent, and in a SHREQ transmitting step, the router:
When the smooth handoff start message is received, the mobile unit transmits a smooth handoff request message to another router that was accessing before moving to the destination wireless network, and in the SHREP transmission process, the other router
A home agent transmits a binding response message to the binding modification message to the mobile through the router in a BA transmission process, and the router transmits a smooth handoff response message to the mobile in the BA sending process. Obtain service rank information indicating the quality required for communication services, and in the allocation process,
The router allocates a buffer amount according to the service rank information obtained in the obtaining step to the mobile for smooth handoff processing, and in the BA / SHACK transmission step, the router receives the smooth handoff reply and the combined response message, After allocating the buffer amount to the mobile, a smooth handoff response message and a binding response message by the home agent are transmitted to the mobile, and in the storing step, the router transmits a packet addressed to the mobile to the mobile, In the packet transmitting step, when the router receives a smooth handoff request message in the packet transmitting step, the packet stored in the storing step is moved to the next wireless network. To the mobile unit. As a result, the buffer can be allocated according to the quality required for the communication service for the mobile unit, so that the buffer resources can be effectively used.

According to the next invention, in the BU / SHIN transmission step, the mobile unit adds the service rank information of the own mobile unit to the smooth handoff start message and transmits the message to the router. By obtaining the service rank information transmitted in the / SHIN transmission step, the service rank information can be obtained.

According to the next invention, in the obtaining step, the router obtains the service rank information by inquiring of the user information server holding the service rank information as the user information of the mobile unit to obtain the service rank information. The effect is that it can be done.

According to the next invention, in the inquiry step, the home agent inquires of the user information server holding the service rank information as the user information of the moving body to acquire the service rank information, and in the BA transmission step, the home agent Adds the service rank information acquired in the inquiry process to the binding response message and transmits the combined response message to the router. In the acquisition process, the router acquires the service rank information transmitted in the BA transmission process. Is obtained.

According to the next invention, in the reduction step, if the router has not received a packet addressed to the mobile for a predetermined period of time after allocating the buffer to the mobile, the router assigns the buffer to the mobile. Reduce buffer size. As a result, it is possible to reduce the number of buffers allocated to the mobile unit from which packet reception is no longer performed, so that the buffer resources can be more effectively used.

According to the next invention, in the increase step, when the router receives the packet addressed to the mobile unit after reducing the buffer amount allocated to the mobile unit in the reduction step, the router assigns the packet to the mobile unit. Increase the buffer amount. As a result, it is possible to increase the number of buffers allocated to the mobile unit from which packet reception is to be performed again, so that buffer resources can be more effectively utilized.

According to the next invention, the operation of the method according to the invention described above can be realized by a computer.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a schematic configuration of a mobile communication system according to a first embodiment of the present invention;

FIG. 2 is a functional configuration diagram illustrating a functional configuration of a router illustrated in FIG. 1;

FIG. 3 is an explanatory diagram illustrating an operation of the mobile communication system according to the first embodiment;

FIG. 4 is a sequence diagram showing an operation of the mobile communication system according to the first exemplary embodiment;

FIG. 5 is a flowchart illustrating an operation of the router according to the first embodiment;

FIG. 6 is a flowchart illustrating a processing procedure of buffer allocation processing of the router according to the first embodiment;

FIG. 7 is a configuration diagram illustrating a schematic configuration of a mobile communication system according to a second embodiment of the present invention;

8 is a functional configuration diagram illustrating a functional configuration of the router illustrated in FIG. 7;

FIG. 9 is an explanatory diagram illustrating an operation of the mobile communication system according to the second embodiment;

FIG. 10 is a sequence diagram showing an operation of the mobile communication system according to the second embodiment.

FIG. 11 is a configuration diagram illustrating a schematic configuration of a mobile communication system according to a third embodiment of the present invention;

FIG. 12 is a functional configuration diagram illustrating a functional configuration of the router illustrated in FIG. 11;

FIG. 13 is an explanatory diagram illustrating the operation of the mobile communication system according to the third embodiment;

FIG. 14 is a sequence diagram showing an operation of the mobile communication system according to the third embodiment.

FIG. 15 is a configuration diagram illustrating a schematic configuration of a mobile communication system according to a fourth embodiment of the present invention;

16 is a functional configuration diagram showing a functional configuration of the router shown in FIG.

FIG. 17 is an explanatory diagram illustrating the operation of the mobile communication system according to the fourth embodiment;

FIG. 18 is a sequence diagram showing an operation of the mobile communication system according to the fourth embodiment.

FIG. 19 is a flowchart of a process of reducing the allocated buffer size of the router according to the fourth embodiment;

FIG. 20 is a flowchart of a process of reviewing the allocated buffer size of the router according to the fourth embodiment;

FIG. 21 is a configuration diagram showing a schematic configuration of a conventional mobile communication system.

FIG. 22 is an explanatory diagram illustrating an operation of a conventional mobile communication system.

FIG. 23 is a sequence diagram showing an operation of a conventional mobile communication system.

FIG. 24 is a flowchart showing the operation of a conventional router.

[Explanation of symbols]

1 home network, 2, 31 home agent, 3 IP network, 4-1 to 4-B opposite node, 5-1 to 5-A external network, 6-1 to 6-
A, 22-1 to 22-A, 32-1 to 32-A, 41-
1-41-A router, 7-1-7-C, 23-1-23
−C mobile unit, 11, 17 I / F unit, 12, 24, 3
3, 42 control unit, 13 storage unit, 14, 25, 34
Service rank acquisition unit, 15 Resource information acquisition unit, 1
6-1 to 16-g buffer area, 21 user information server.

Continued on the front page F term (reference) 5K030 GA06 HA08 HC01 HD03 JA11 JL08 JT09 KA03 LB05 5K034 AA01 AA10 DD03 EE03 EE11 FF11 HH21 KK27 5K067 AA21 BB03 BB04 BB21 CC08 DD53 EE02 EE10 EE16 HH23 JJ13

Claims (11)

[Claims] A mobile unit that performs wireless communication while moving between a plurality of wireless networks, and a relay unit that is provided for each of the wireless networks and relays a packet transmitted by the mobile unit and a packet addressed to the mobile unit. And a relay device for storing packets addressed to the mobile object by a predetermined buffer amount. When the relay device performs a handoff process with the mobile object, a communication service for the mobile object is provided. Acquisition means for acquiring service rank information indicating the quality required for the control means, and control means for allocating the buffer amount according to the service rank information acquired by the acquisition means to the moving object and controlling the accumulation processing. A mobile communication system comprising: 2. The relay device has resource information acquisition means for acquiring resource information indicating the remaining buffer resources that can be allocated, and the control means responds to the resource information acquired by the resource information acquisition means. The mobile communication system according to claim 1, wherein the allocated buffer amount is allocated to the mobile unit. 3. The control unit, after allocating the buffer amount to the mobile unit, if the packet addressed to the mobile unit has not been received for a predetermined time or more, reduces the buffer amount allocated to the mobile unit. The mobile communication system according to claim 1 or 2, wherein: 4. The method according to claim 1, wherein the control unit increases the buffer amount allocated to the mobile unit after reducing the buffer amount allocated to the mobile unit and receiving a packet addressed to the mobile unit. The mobile communication system according to claim 3, wherein 5. A handoff method performed when a mobile unit performing wireless communication moves between a plurality of wireless networks, wherein the mobile unit adds a smooth handoff process correspondence information by a router of the destination wireless network. An RA receiving step of receiving an advertisement message; a binding correction message in which the mobile unit registers an IP address allocated in the destination wireless network with a home agent of the mobile unit; and a smooth handoff requesting a smooth handoff process. A BU / SHIN transmitting step of transmitting a start message to the router; a BU transmitting step of transmitting the binding correction message to the home agent when the router receives the binding correction message; Start message The mobile unit sends a smooth handoff request message to another router that was accessing the mobile unit before moving to the destination wireless network. An SHREP transmitting step of transmitting a handoff reply message to the router; a BA transmitting step of transmitting, by the home agent, a binding response message to a binding modification message to the mobile via the router; An acquisition step of acquiring service rank information indicating quality required for a communication service; and the router allocating a buffer amount according to the service rank information acquired in the acquisition step to the mobile unit for a smooth handoff process. Process and the loop Receives a smooth handoff answer and a binding response message, allocates the buffer amount to the mobile, and then sends a smooth handoff response message and a binding response message by the home agent to the mobile, BA / SHACK transmission The router transmits a packet addressed to the mobile to the mobile, and stores the packet by the buffer amount allocated to the mobile in the allocation step; Transmitting a packet stored in the storing step to the mobile unit that has moved to the next wireless network, when receiving a handoff request message, a packet transmitting step. 6. In a BU / SHIN transmitting step, the mobile unit adds the service rank information of the own mobile unit to the smooth handoff start message and transmits the message to the router. In the obtaining step, the router includes: The BU / SHIN
The handoff method according to claim 5, wherein the service rank information transmitted in the transmitting step is obtained. 7. The method according to claim 5, wherein in the obtaining step, the router obtains the service rank information by inquiring a user information server holding the service rank information as user information of the mobile unit. The described handoff method. 8. The BA transmission step, wherein the home agent includes an inquiry step of inquiring a user information server holding the service rank information as user information of the mobile body to acquire the service rank information. The home agent adds the service rank information obtained in the inquiry step to the binding response message and transmits the service response information to the router. In the obtaining step, the router transmits the service transmitted in the BA transmission step. The method according to claim 5, wherein rank information is obtained. 9. If the router has not received a packet addressed to the mobile for a predetermined time after allocating the buffer to the mobile, the router reduces the buffer allocated to the mobile. The handoff method according to any one of claims 5 to 8, further comprising a reduction step. 10. When the router receives a packet addressed to the mobile unit after the router reduces the buffer amount allocated to the mobile unit in the reduction step, the router allocates the buffer amount allocated to the mobile unit. The method of claim 9, further comprising an increasing step. 11. A program for causing a computer to execute the method according to claim 5. Description: