JP2001339752A - External agent and smooth hand-off method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome the problem such that voice is declined at a hand-off, when discarding in order of occurrence from the oldest IP packet upon receiving of new IP packet, in a status of filling a buffer at the hand-off. SOLUTION: When a new voice data is received after filling the buffer with the voice data, a data to be discarded is selected not to continue in time series, and after the selected data is scrapped from the buffer, the new voice data is stored into the buffer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile terminal which starts buffering of data addressed to the mobile terminal before the mobile terminal moves and performs handoff, and transfers the buffered data to the mobile terminal via a foreign agent at the destination. The present invention relates to an external agent for transferring to a device and a smooth handoff method.

[0002]

2. Description of the Related Art When a mobile terminal (Mobile Terminal, hereinafter abbreviated as MT) having an IP (Internet Protocol) address moves across subnets, the mobile terminal can maintain communication without interrupting a session. , IETF (Internet Engineering Task Force) M
obileIP (Request For Comment 2002) has been proposed.

[0003] Next, packet transmission in MobileIP will be described. For example, when the mobile terminal device moves to a foreign agent domain, the mobile terminal device obtains its own address in the domain as a care-of address, and notifies the home agent via the foreign agent of the care-of address. I do. The home agent registers the care-of address from the mobile terminal device in association with the home address of the mobile terminal device.

[0004] On the other hand, when transmitting an IP packet to a mobile terminal device, a partner terminal device as a transmission partner of the mobile terminal device transmits the IP packet to a home address of the mobile terminal device. The IP packet reaches the home agent via the IP network. After encapsulating the IP packet, the home agent transfers the IP packet to the care-of address of the mobile terminal device based on the registration information of the mobile terminal device. When the foreign agent receives the encapsulated IP packet,
The encapsulation is released, and the original IP packet is supplied to the mobile terminal device having the care-of address.

[0005] In this way, even if the mobile terminal device moves across domains, the IP packet addressed to the mobile terminal device reaches the mobile terminal device via the home agent and the foreign agent.

However, when an IP packet destined for a mobile terminal device is made to reach the mobile terminal device via a home agent, that is, in the case of triangular routing, there is a problem that transmission delay increases.
When performing data transmission that is sensitive to delay such as VoIP (Voice over IP), such a transmission delay becomes a serious problem.

[0007] In view of this, an Internet draft (draft-ietf-mobileip-optim-08.txt) of IETF proposes a route optimization for solving the transmission delay problem due to the triangular routing described above.
This route optimization uses a protocol for setting a shortcut path from the partner terminal device to the care-of address of the mobile terminal device without passing through the home agent.

[0008] According to this route optimization, the other terminal periodically sends a Bind Request message (Bind Request) with the home agent of the mobile terminal in order to obtain the current care-of address of the mobile terminal. Message) and a Bind Update Message.
The partner terminal device acquires the current care-of address of the mobile terminal device based on the binding update message obtained periodically, encapsulates an IP packet addressed to the mobile terminal device, and transmits the encapsulated IP packet to the care-of address.

Therefore, an IP packet addressed to the mobile terminal from the partner terminal arrives at the mobile terminal without passing through the home agent. In this state, an IP tunnel from the partner terminal device to the external agent is formed. This eliminates triangular routing.

FIG. 10 is a diagram for explaining route optimization in the conventional MobileIP. In FIG. 10, reference numeral 1 denotes a mobile terminal such as a third-generation mobile phone, a PDA (Personal Data Asistant), or a mobile personal computer to which an IP address in a home domain (hereinafter, referred to as a home address) is fixedly assigned. Device, 2
Is a home agent (Ho) configured as a computer located in the home domain to which the mobile terminal device 1 belongs.
me Agent, HA). Reference numeral 3 denotes a partner terminal device such as a computer with which the mobile terminal device 1 communicates. The partner terminal device 3 may be either a fixed terminal device or a mobile terminal device. Note that the other terminal device is connected to CN (Corr
esponding Node). Reference numeral 4 denotes an IP network, and reference numeral 105-1 denotes a foreign agent (Foreign Agent) located in a predetermined domain and having a unique care-of address.
, FA), 105-2 is an external agent arranged in a predetermined domain and having a unique care-of address. In this case, the external agent 105
Reference numeral -1 denotes a foreign agent from which the mobile terminal device 1 has moved, and foreign agent 105-2 denotes a foreign agent to which the mobile terminal device 1 has moved.

FIG. 10A shows an external agent 105.
1 illustrates a state immediately after the mobile terminal device 1 has moved from the domain of the foreign agent 105-2 to the domain of the foreign agent 105-2. In this case, the IP tunnel is still formed from the partner terminal device 3 to the external agent 105-1 by the above-described route optimization.

After moving, the mobile terminal device 1 acquires a care-of address, transmits a registration request message to the home agent 2, and transmits a transfer instruction to the foreign agent 105-1 in the source domain.

[0015] Upon receiving the registration request message, home agent 2 updates the registration information of mobile terminal device 1. Further, after receiving the transfer instruction, the foreign agent 105-1 of the source domain receives the encapsulated IP packet addressed to the mobile terminal device 1 as shown in FIG. Then, the IP packet is encapsulated again and transferred to the care-of address of the mobile terminal device 1 at the destination. As a result, the foreign agent 105-1 at the destination moves from the foreign agent 105-1 at the source.
IP tunnels up to 5-2 are formed.

Further, as shown in FIG. 10C, the foreign agent 105-1 of the source domain sends a notice of switching of the care-of address due to the change of the domain in which the mobile terminal device 1 exists to the home agent 2. Send. When the home agent 2 receives the switching notification, the home agent 2 transfers the notification to the partner terminal device 3. Upon receiving the switching notification, the partner terminal device 3 changes the destination of the IP packet to the mobile terminal device 1 to a new care-of address. As a result, the I to the destination foreign agent 105-2 from the destination terminal device 3
A P tunnel is formed.

In this manner, the IP packet addressed to the mobile terminal device 1 during the period from the reception of the transfer instruction by the foreign agent 105-1 at the movement source to the reception of the switching notification by the partner terminal device is not discarded. The mobile terminal 1 is reached.

However, during the period from the handoff of the mobile terminal device 1 to the reception of the transfer instruction by the foreign agent 105-1 at the movement source, the I to the mobile terminal device 1
The P packet will be discarded.

Therefore, according to the IETF's Internet draft (draft-mkhalil-mobileip-buffer-00.txt), when the mobile terminal device 1 performs a handoff, the foreign agent 105-1 of the transfer source is addressed to the mobile terminal device 1. When the transfer request from the mobile terminal device 1 after the movement is received, the buffered data is transferred to another foreign agent 105 of the movement destination.
This problem is solved by transferring the data to the mobile terminal device 1 through -2.

FIG. 11 is a diagram for explaining a conventional smooth handoff method. FIG. 12 is a diagram for explaining buffer management in the conventional smooth handoff method. FIG.
FIG. 2 is a diagram for explaining transfer of buffered data to a mobile terminal device 1 in a conventional smooth handoff method.

As shown in FIG. 11A, when the mobile terminal device 1 detects a handoff based on the radio wave intensity from the foreign agent 105-1 or the like, it transmits a buffer request to the foreign agent 105-1. Upon receiving the buffer request, the foreign agent 105-1 buffers the IP packet addressed to the mobile terminal device 1, as shown in FIG. At this time, the IP packets are sequentially accumulated in the buffer in chronological order, and when a new IP packet is received in a state where the buffer is full, the oldest IP packet is received.
P packets are discarded in order.

Thereafter, as shown in FIG. 11 (b), when the handoff is completed, the mobile terminal device 1 sends a buffer discharge request to the foreign agent 105-1 at the source via the foreign agent 105-2 at the destination. Send When the foreign agent 105-1 at the transfer source transmits the buffer discharge request, as shown in FIG. 13A, it forwards each buffered IP packet to the care-of address of the mobile terminal device 1 after the transfer. Encapsulation, FIG. 13 (b)
Send as shown. Foreign agent 10 at the destination
5-2, upon receiving the IP packet addressed to the care-of address of the mobile terminal device 1, decapsulates the packet and transmits the original IP packet to the mobile terminal device 1, as shown in FIG. During this time, the notice of switching of the care-of address of the mobile terminal device 1 is received by the partner terminal device 3, and thereafter, as shown in FIG. The IP packet is encapsulated and transmitted to a new care-of address of the terminal device 1.

Thus, the conventional smooth handoff is performed. At this time, the buffer provided in the external agent is optimized in consideration of the following points in order to solve the above-described problem in the route optimization of MobileIP. (1) A buffer is allocated to each mobile terminal device managed by the foreign agent at a timing when a buffer request is issued. (2) The buffer is required only during the transition period (usually within a few seconds) for switching the foreign agent by handoff (that is, switching the care-of address), and its size is from several IP packets to about 100 IP packets. It's as small as a minute.

In addition to the above, various techniques have been proposed as general-purpose buffer management techniques. For example, JP
In the buffer management method disclosed in JP-A-190059, when a plurality of packets having any one of a plurality of types of priority are buffered in one buffer, a new packet appears in a state where the buffer is full. Then, the packet with the lowest priority among the packets in the buffer and the new packet is discarded, and the remaining packets are stored in the buffer.

In the buffer management method disclosed in Japanese Patent Application Laid-Open No. 59-190575, for example, a time limit for a packet to exist in a buffer is set, and a packet after the time limit is discarded.

[0024]

Since the conventional smooth handoff method is configured as described above, when a new IP packet is received with the buffer being full at the time of handoff, the oldest IP packet is received. When discarding in order from the first, there is a problem that, for example, when voice data to be transmitted and received requires real-time properties as in a third-generation mobile phone system, voice deteriorates at the time of handoff.

In the buffer management method described in Japanese Patent Laid-Open No. 59-190575, packets are discarded when a timeout occurs due to a queuing delay. However, the present invention is applied to a third-generation mobile phone network. Then, at the time of handoff of the portable terminal device, there is a problem that an IP packet is lost and voice quality is deteriorated.

Further, in the buffer batch transfer in the IETF Internet draft (draft-mkhalil-mobileip-buffer-00.txt), buffered IP packets are continuously transmitted. Extremely short Voice ov when applied to
Since the er IP IP packet is transmitted continuously, there is a problem that the load of the routing process in the network increases.

In the buffer management method described in Japanese Patent Application Laid-Open No. 2-190059, for example, in a third-generation mobile phone network, calls and Internet access are exclusively used, and a mobile terminal device (in this case,
When only one type (for example, Voice Over IP) of an IP packet is buffered in a buffer mounted corresponding to a mobile phone, all data have the same priority. Therefore, discarding based on the priority by this method is performed. It is difficult to apply controls.

The present invention has been made to solve the above-described problem. When new data is received after the buffer is filled with data, the discarded data is discontinuous in time series. An external agent that selects data to be discarded so as to discard the selected data from the buffer, and then stores new data in the buffer, thereby suppressing voice degradation during handoff. The aim is to obtain a smooth handoff method.

Further, according to the present invention, when a predetermined close-out transmission time has elapsed from the buffering start time, all voice data stored in the buffer is transferred to the mobile terminal device, so that a packet discarded is discarded. It is an object of the present invention to provide an external agent and a smooth handoff method capable of reducing the number and suppressing voice deterioration at the time of handoff.

Further, according to the present invention, it is determined whether or not a predetermined closing transmission time has elapsed for each buffered audio data, and the audio data for which the predetermined closing transmission time has elapsed is transferred to the mobile terminal device. It is another object of the present invention to provide an external agent and a smooth handoff method capable of reducing the number of discarded packets and suppressing voice degradation at the time of handoff.

Further, according to the present invention, a new packet is generated by adding the same header as each packet to the concatenation of the contents of each buffered packet, and the new packet is transferred. It is an object of the present invention to provide a foreign agent and a smooth handoff method capable of reducing the number and the load of a routing process.

[0032]

According to the present invention, there is provided a foreign agent for receiving data addressed to a mobile terminal device, and storing the data received by the receiving means in a buffer having a predetermined capacity. If new data is received after is filled with data, select the data to be discarded so that the discarded data becomes discontinuous in chronological order, and after discarding the selected data from the buffer,
Buffer management means for storing new data in the buffer.

The external agent according to the present invention includes data classification means for classifying the data addressed to the mobile terminal device received by the reception means into voice data and other data, and the buffer management means converts the voice data into the data described above. It is made to buffer as follows.

[0034] The external agent according to the present invention determines whether or not the data received by the receiving means is voice data based on the type of session established by the mobile terminal device to be handed off. It is.

The external agent according to the present invention determines whether or not the data received by the receiving means is voice data based on the type of the protocol.

The external agent according to the present invention is Vo
ice over IP audio data is buffered.

The smooth handoff method according to the present invention comprises the steps of: storing data received by a foreign agent at a movement source in a buffer having a predetermined capacity; and discarding new data after the buffer is filled with data. And a step of selecting data to be discarded so that data to be discarded is discontinuous in time series, and a step of discarding the selected data from the buffer and storing new data in the buffer.

The external agent according to the present invention stores transmission / reception means for transmitting / receiving data and voice data received by the transmission / reception means in a buffer having a predetermined capacity, and a predetermined closing transmission time from the buffering start time. And buffer management means for transferring all audio data stored in the buffer to the mobile terminal device via the transmission / reception means when the time has elapsed.

The smooth handoff method according to the present invention comprises the steps of: storing voice data received by a foreign agent of a movement origin in a buffer having a predetermined capacity; And transferring all the voice data stored in the mobile terminal to the mobile terminal device.

The external agent according to the present invention stores transmission / reception means for transmitting / receiving data and voice data received by the transmission / reception means in a buffer having a predetermined capacity, and a predetermined closing transmission time elapses for each voice data. Buffer management means for judging whether or not the audio data has passed a predetermined part-time transmission time to the mobile terminal device via the transmission / reception means.

In the smooth handoff method according to the present invention, a step of storing voice data received by a foreign agent of a movement source in a buffer having a predetermined capacity and a step of determining whether or not a predetermined closing transmission time has elapsed for each voice data. And transmitting the audio data for which a predetermined closing transmission time has elapsed to the mobile terminal device.

The external agent according to the present invention comprises: a transmitting / receiving means for transmitting / receiving data; a packet received by the transmitting / receiving means being stored in a buffer having a predetermined capacity; and the contents of each buffered packet are connected. A buffer management means for generating a new packet by adding the same header as the packet and transferring the new packet via the transmission / reception means.

In the smooth handoff method according to the present invention, a step of storing a packet received by a foreign agent at a movement source in a buffer having a predetermined capacity, and a step of connecting the contents of each buffered packet to the same header as the packet To generate a new packet, and transfer the new packet.

[0044]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a block diagram showing a configuration of the external agents 5-1 and 5-2 according to the first embodiment of the present invention. The external agents 5-1 and 5-2 correspond to FIG.
1 is used instead of the conventional external agents 105-1 and 105-2 in the network shown in FIG.

In FIG. 1, reference numeral 11 denotes a program stored in a ROM 12 or a hard disk drive 13 in a RAM.
15 to be loaded and executed (buffer management means,
A ROM 12 in which programs and data to be used at the time of startup are stored in advance;
Reference numeral 3 denotes a hard disk drive for storing a program describing buffer management and functions of other external agents in MobileIP. Reference numeral 14 denotes an interface for connecting the hard disk drive 13 to a bus 18; And a RAM provided with a buffer at the time of handoff.

16 is connected to the IP network 4 and
A network interface (receiving means, transmitting / receiving means) for transmitting and receiving P packets is a wireless interface 17 for wirelessly transmitting and receiving IP packets to and from the mobile terminal device 1 existing in its own domain.

Next, the operation will be described. FIG. 2 is a diagram illustrating buffer management in the external agent 5-1 according to the first embodiment.

The mobile terminal 1 is connected to the foreign agent 5-
When a handoff is detected based on the radio wave intensity from No. 1 or the like, a buffer request is transmitted to the external agent 5-1. Upon receiving the buffer request, the foreign agent 5-1 buffers the IP packet addressed to the mobile terminal device 1, as shown in FIG. At this time, the IP packet is
The IPs are accumulated in the buffer in time series, and when a new IP packet is received in a state where the buffer is full, the IP to be discarded is discarded so that the discarded IP packets become discontinuous in time series. Select the packet and select the IP
After discarding the packet from the buffer, a new IP packet is stored in the buffer.

That is, as shown in FIG. 2B, for example, the buffer for the mobile terminal 1 is filled with the IP packets “a”, “b”, “c”, “d”, and “e”. When a new IP packet “f” is received in the state of being present, the oldest IP packet “a” is first discarded and the IP packet “f” is buffered, as shown in FIG. . Next, when a new IP packet “g” is received, as shown in FIG.
The oldest IP packet "c" is discarded and IP packet "g" is buffered. In addition, new IP
When the packet “h” is received, as shown in FIG. 2E, the third oldest IP packet “e” is discarded in the buffer, and the IP packet “h” is buffered. In this way, the discarded IP packets (in this case, “a”, “c”, and “e”) are discontinuous in time series.

Further, when the IP packet to be discarded becomes the latest one, the next I to be discarded becomes
Let the P packet be the oldest.

When there are a plurality of mobile terminal devices 1 to be handed off, a buffer is provided for each mobile terminal device 1 in the RAM.
15. This buffer is secured when the mobile terminal device 1 moves to the domain of the foreign agent 5-1 or dynamically when a buffer request is received.

Thereafter, when the handoff is completed, the mobile terminal device 1 transmits a buffer discharge request to the foreign agent 5-1 of the movement source via the foreign agent 5-2 of the movement destination. When the source foreign agent 5-1 transmits the buffer discharge request, it encapsulates each buffered IP packet toward the care-of address of the mobile terminal device 1 after the transfer, and transmits the encapsulated IP packet. Upon receiving the IP packet addressed to the care-of address of the mobile terminal device 1, the foreign agent 5-2 at the destination releases the encapsulation and transmits the original IP packet to the mobile terminal device 1. During this time,
The notification of switching of the care-of address of the mobile terminal 1 is received by the partner terminal 3, and thereafter, the partner terminal 3 transmits the IP packet to the new care-of address of the mobile terminal 1 as described above. Is encapsulated and sent.

The IP packets discarded in this manner may be discontinuous in time series only for data requiring real-time properties. Voice over requires real-time data
There is IP voice data and the like. Further, in FIG. 2, every other IP packet is discarded in chronological order.
Every other or every third may be used.

The external agents 5-1 and 5-2 according to the first embodiment also execute operations specified in Mobile IP.

As described above, according to the first embodiment, the data received by the foreign agent 5-1 at the movement source is stored in the buffer having a predetermined capacity, and after the buffer is filled with the data, a new data is stored. When data is received, select data to be discarded so that discarded data becomes discontinuous in time series, discard the selected data from the buffer, and store new data in the buffer. As a result, the effect of suppressing the deterioration of the sound at the time of handoff can be obtained.

Embodiment 2 The foreign agent 5-1 according to the second embodiment of the present invention includes, for example, voice data of Voice over IP and other data (Voice over IP) as data addressed to the mobile terminal device 1.
Even in the case where IP control data and general Internet access data) are mixed, audio data and other data are classified, and buffer management is performed only for Voice over IP audio data as in the first embodiment. It is like that.

The external agent 5-1 according to the second embodiment of the present invention has the same configuration as that according to the first embodiment, and stores a program describing the following operation in the hard disk drive 13, and the CPU 11 Execute.

Next, the operation will be described. FIG. 3 is an SDL (Specification and Description Language) diagram for explaining the operation of the external agent 5-1 according to the second embodiment. FIG. 4 shows an external agent 5 according to the second embodiment.
FIG. 3 is a diagram for explaining buffer management at -1.

External agent 5 according to the second embodiment
When receiving a buffer request from the mobile terminal device 1 in step ST1, 1 provides a buffer in step ST2 and initializes the buffer. At this time, the external agent 5
-1 sets the discard pointer pDiscard to an initial value of 1.

Thereafter, when receiving the IP packet addressed to the mobile terminal device 1, the foreign agent 5-1 determines whether the IP packet is voice over IP voice data or other data by a predetermined method. to decide. The external agent 5-1 is a Voice over
If it is determined that the audio data of the IP has been received (step ST11), it is determined whether or not the buffer is full in step ST12, and if it is determined that the buffer is not full, the IP of the audio data is determined in step ST13. Allocate a storage area for packets.

Here, management of IP packets in the buffer will be described. The packets in the buffer are related in chronological order by a list structure. At this time, a list structure for audio data packets is provided independently of a list structure for all packets. When a packet is added to the buffer, an area for two pointers is added to the packet as shown in FIG. One of the pointers is for the list structure of all packets and points to the previous packet in chronological order, and the other pointer is for the list structure of audio data and , And indicates the packet of the previous audio data in chronological order.

The external agent 5-1 updates the chain of pointers in the list structure in step ST14, and adds the received voice data packet to the buffer in step ST15.

On the other hand, if it is determined in step ST12 that the buffer is full, the foreign agent 5-1 discards the packet indicated by the discard pointer in step ST16, and increases the value of the discard pointer by 1 in step ST17. Then, in step ST18, the foreign agent 5-1 determines whether or not the value of the discard pointer has reached the upper limit value (maxBufferNo) of the number of packets in the buffer, and the value of the discard pointer has reached the upper limit value. If the judgment is made, the value of the discard pointer is reset to 1 in step ST19.

After that, the external agent 5-1 updates the chain of pointers of each list structure in step ST14, and adds the packet to the area of the discarded packet in the buffer in step ST15.

For example, as shown in FIG. 4B, the buffer for the mobile terminal device 1 is composed of audio data IP packets “a”, “b”, “c”, “d” and two other IP packets. When a new IP packet "e" of voice data is received in a state where the packet is filled with the above, first, as shown in FIG. 4C, the discard pointer pDiscard (=
The oldest IP packet “a” of the audio data pointed to by 1) is discarded, the IP packet “e” is buffered,
The value of the discard pointer pDiscard is incremented by 1 (pDiscard = 2).

Next, when a new IP packet “f” of voice data is received, as shown in FIG. 4D, the second oldest voice packet in the buffer pointed to by the discard pointer pDiscard (= 2) is received. The IP packet “c” of the data is discarded, the IP packet “f” is buffered, and the value of the discard pointer pDiscard is increased by 1 (p
Discard = 3).

If the received IP packet is data other than voice data (step ST21),
In step ST22, the external agent 5-1
Add the IP packet to the buffer as it is when the buffer is not full, and discard the oldest IP packet other than voice data and add a new IP packet to the buffer when the buffer is full .

Then, upon receiving a buffer discharge request from the mobile terminal device 1 after the movement (step ST31),
The foreign agent 5-1 of the movement source performs step ST32.
In, the IP packet stored in the buffer is
The mobile terminal device 1 encapsulates and transmits it to the care-of address after the movement of the mobile terminal device 1, and releases the storage area of the buffer in step ST33.

The other operation is the same as that of the first embodiment, and the description is omitted.

Further, in the second embodiment, voice over IP voice data and other data are mixed in one buffer, but both may be managed by separate buffers and lists. Of course. In this case, the buffer for the IP packet of the voice data of Voiceover IP may be managed as described in the first embodiment, and the buffer for the IP packet of the other data may be managed in the same manner as the conventional one.

As described above, according to the second embodiment, the received data addressed to the mobile terminal device is classified into voice data and other data, and the discarded data of the voice data is time-series. In this case, for example, even in a mobile phone capable of simultaneously performing the Internet access and the voice call, it is possible to suppress the deterioration of the voice at the time of handoff.

Embodiment 3 The foreign agent 5-1 according to the third embodiment of the present invention, based on the type of session established by the mobile terminal device 1 to be handed off,
This is to determine whether the received data is audio data.

The external agent 5-1 according to the third embodiment of the present invention has the same configuration as that of the first embodiment, and stores a program describing the following operation in the hard disk drive 13 and the CPU 11 Execute.

Next, the operation will be described. FIG. 5 is an SDL diagram for explaining the operation of the external agent 5-1 according to the third embodiment. When the present invention is applied to a third-generation mobile phone network, the session held by the mobile phone at the time of handoff is either a call (such as VoIP) or Internet access, and both are generally mutually exclusive. Become.

Therefore, the mobile terminal 1 notifies the external agent 5-1 of the type of the session being opened (the application being executed) simultaneously with the buffer request. In step ST41, the foreign agent 5-1 according to the third embodiment stores whether or not the type of the session is a call session for each mobile terminal device 1 to be handed off.

Thereafter, when foreign agent 5-1 receives the IP packet addressed to mobile terminal device 1 (step ST51), in step ST52, whether or not the session at the time of handoff of mobile terminal device 1 is a call session. Judge.

If it is determined that the session at the time of handoff is a call session, the external agent 5-1 sends
In step ST53, the protocol and port number of the session are checked. In VoIP, UDP (User Datagram Pr
otocol) / RTP (Real Time Protocol) is used, whereas UDP is used for a voice control signal. As for the voice control signal, the UDP port number used is H.264 depending on the type. 323 and SIP (Se
curity Parameter Index). Therefore, the audio data and the audio control signal can be further classified based on the UDP port number.

Then, in step ST54, the foreign agent 5-1 receives the IP packet from the UDP
It is determined whether or not the IP packet is for a voice control signal based on the port number of the above. If it is determined that the IP packet is not for the voice control signal but for voice data, the process proceeds to step ST55. , The same processing as in steps ST12 to ST19 in FIG. 3 is executed.

On the other hand, if it is determined that the type of session is not a call session but a session other than that, and if it is determined that the received IP packet is for a voice control signal, the process proceeds to step ST56.
The IP packet is processed in the same manner as the processing in step ST22 in FIG. That is, the IP packet of the voice control signal in the call session is handled in the same manner as the IP packet of data other than the voice data. If the voice control signal is processed in the same manner as the voice data, the processes in steps ST53 and ST54 may be omitted.

The other operations are the same as those according to the second embodiment, and a description thereof will be omitted.

As described above, according to the third embodiment, whether or not received data is voice data is determined based on the type of session established by mobile terminal device 1 to be handed off. As a result, an effect is obtained that audio data can be accurately classified.

Embodiment 4 The external agent 5-1 according to the fourth embodiment of the present invention determines whether or not received data is voice data based on the type of protocol.

The external agent 5-1 according to the fourth embodiment of the present invention is configured in the same manner as that according to the first embodiment. A program describing the following operation is stored in the hard disk drive 13 and the CPU 11 Execute.

Next, the operation will be described. FIG. 6 is an SDL diagram for explaining the operation of the external agent 5-1 according to the fourth embodiment.

External Agent 5- in Embodiment 4
1 receives an IP packet addressed to the mobile terminal device 1 that has been handed off after the start of buffering (step ST6).
1) In step ST62, it is determined whether or not the UDP header is used as the fourth layer of the OSI reference model.

When determining that the UDP header is used as the fourth layer, in step ST63, the foreign agent 5-1 determines whether the RTP header is used as the seventh layer. R as the seventh layer
When determining that the TP header is used, the external agent 5-1 determines in step ST64 that the port number that has received the IP packet is within the preset port number range for Voice over IP. It is determined whether or not.

The UDP header is used as the fourth layer, the RTP header is used as the seventh layer, and the port number for receiving the IP packet is set in advance for Voice over IP. Only when the port number is within the range of the port number, step ST65
, The external agent 5-1 performs the same processing as in steps ST12 to ST19 in FIG.

Otherwise, in step ST66, the IP packet is stored in step S66 in FIG.
The processing is performed in the same manner as the processing in T22. That is, the IP packet of the voice control signal in the call session is handled in the same manner as the IP packet of data other than the voice data.
If the voice control signal is processed in the same manner as the voice data, the process of step ST63 may be omitted.

The other operations are the same as those according to the second embodiment, and a description thereof will not be repeated.

As described above, according to the fourth embodiment, whether or not received data is voice data is determined based on the type of protocol. Therefore, it is possible to obtain an effect that audio data can be accurately classified without acquiring the audio data.

Embodiment 5 If the time from starting the buffering of the IP packet to receiving the buffer discharge request is long, the request delay time between the mobile terminal device 1 and the partner terminal device 3 may not be satisfied. In general, Voice over IP is delay-critical, and a system maximum delay time (requested delay time) is determined, and a packet received beyond this time becomes invalid. Therefore, IP packets that do not satisfy the required delay time are discarded.

Therefore, when a predetermined closing transmission time has elapsed since the buffering start time, the external agent 5-1 according to the fifth embodiment of the present invention transmits all the audio data stored in the buffer to the mobile terminal 1 It is intended to be forwarded to.

The external agent 5-1 according to the fifth embodiment of the present invention is configured in the same manner as that according to the first embodiment. A program describing the following operation is stored in the hard disk drive 13 and the CPU 11 Execute.

Next, the operation will be described. FIG. 7 is an SDL diagram for explaining the operation of the external agent 5-1 according to the fifth embodiment.

Upon receiving the buffer request (step ST1), external agent 5-1 executes an initialization process (step ST2) (buffering start time), and in step ST71, waits until the buffered IP packet has been ceased and transmitted. Activates a timer that measures the time (close transmission time). This time is set shorter than the required delay time.

Thereafter, the timer times out before receiving the buffer discharge request (step ST8).
1) In step ST82, the foreign agent 5-1 collectively transfers the buffered IP packets to the moved mobile terminal device 1 in step ST82.
At 3, the storage area of the buffer is released.

On the other hand, when receiving the buffer discharge request (step ST91), the external agent 5-1 determines whether or not the buffering time of the IP packet exceeds the required delay time in step ST92. If it is determined that the delay time has been exceeded, all buffered IP packets are discarded and the storage area of the buffer is released (step ST93). Otherwise, the buffered IP packet is transferred and the storage area of the buffer is changed. Release (step ST82, step ST83).

[0098] In the fifth embodiment, the close-out timer is activated when a buffer request is received, but is activated at the timing when the IP packet addressed to the mobile terminal device 1 is first buffered (buffering start time). It may be.

As described above, according to the fifth embodiment, when a predetermined close-out transmission time has elapsed from the buffering start time, all the audio data stored in the buffer is transferred to the mobile terminal device. As a result, the number of discarded packets can be reduced, and the effect of suppressing voice degradation during handoff can be obtained.

Embodiment 6 FIG. The external agent 5-1 according to the sixth embodiment of the present invention determines whether a predetermined close-out transmission time has elapsed for each IP packet of audio data,
The packet is transferred to the mobile terminal device 1.

The external agent 5-1 according to the sixth embodiment of the present invention has the same configuration as that of the first embodiment, and stores a program describing the following operation in the hard disk drive 13, and the CPU 11 Execute.

Next, the operation will be described. FIG. 8 is an SDL diagram for explaining the operation of the external agent 5-1 according to the sixth embodiment.

External agent 5 according to the sixth embodiment
1 receives the buffer request (step ST1), as in the fifth embodiment, and initializes (step ST2)
Is executed (buffering start time), and step ST7 is performed.
In step 1, a closing timer for measuring the time until the buffered IP packet is completely transmitted (closing transmission time) is started.

Thereafter, before the buffer discharge request is received, the timer times out (step ST8).
1), the external agent 5-1 executes step ST111
In step ST1, after extracting the timing data described in the Voice over IP RTP header in the IP packet of the oldest audio data,
At 12, only the IP packet is transferred to the mobile terminal device 1.

In step ST113, the foreign agent 5-1 extracts the timing data described in the Voice over IP RTP header in the next oldest audio data IP packet, and in step ST114, transfers the transferred IP packet. Calculate the difference from the timing data extracted from
At T115, a part-time timer for measuring the time of the difference is started.

That is, when the buffer discharge request is not received, the parting-out timer is set sequentially, and the buffered audio data is transferred one by one from the oldest one.

The other operation is the same as that of the fifth embodiment, and the description is omitted.

As described above, according to the sixth embodiment, it is determined whether or not a predetermined close-out transmission time has elapsed for each IP packet of audio data, and the audio data of which the predetermined close-out transmission time has elapsed is determined. Since the IP packet is transferred to the mobile terminal device, the number of discarded packets can be reduced, and the effect of suppressing voice degradation at the time of handoff can be obtained.

Embodiment 7 FIG. The foreign agent 5-1 according to the seventh embodiment of the present invention generates a new packet by adding the same header as each packet to the concatenation of the contents of each buffered packet, and generates the new packet. The transfer is performed to the mobile terminal device 1.

The external agent 5-1 according to the seventh embodiment of the present invention has the same configuration as that according to the first embodiment, and stores a program describing the following operation in the hard disk drive 13, and the CPU 11 Execute.

Next, the operation will be described. FIG. 9 is a view for explaining transfer of data buffered in the foreign agent 5-1 to the mobile terminal device 1 after movement according to the seventh embodiment.

External agent 5 according to the seventh embodiment
When the buffered packet is transferred to the mobile terminal device 1 after the movement, the content 1 extracts the contents of each packet shown in FIG. 9A and connects them (Voic
In the case of e over IP, a new packet 31 is generated by adding the same header to each packet to several to several tens of bytes of audio data), and as shown in FIG. The transfer is performed to the care-of address of the mobile terminal device 1 after the movement.

When the foreign agent 5-2 of the movement destination receives the packet 31, it adds the header of the original IP packet to the contents of each original packet, and
The original IP header is restored and transmitted to the mobile terminal device 1.

In the case of Voice over IP, since all contents have the same length, when the foreign agent 5-2 at the movement destination restores the IP packet, the Length field is unnecessary.

In the seventh embodiment, one IP packet 31 is packed irrespective of the type of content of the buffered IP packet. However, only audio data may be packed.

Furthermore, in the seventh embodiment, the contents of all buffered IP packets are packed into one IP packet.
The number of IP packets to be packed may be set as appropriate, or the length of packed IP packets 31 may be limited.

As described above, according to the seventh embodiment, a new packet is generated by adding the same header as each packet to the concatenated contents of each buffered packet, and the new packet is generated. Since the packets are transferred to the mobile terminal device, the number of transferred packets can be reduced, and the load of the routing process can be reduced. Further, since the header area is deleted, the substantial transfer length is shortened, and the utilization efficiency of the line band is improved.

[0118]

As described above, according to the present invention, the data received by the foreign agent at the movement source is stored in a buffer having a predetermined capacity, and new data is received after the buffer is filled with data. , Select the data to be discarded so that the discarded data is discontinuous in time series,
Since the new data is stored in the buffer after the selected data is discarded from the buffer, it is possible to suppress the deterioration of the sound at the time of handoff.

According to the present invention, the data addressed to the mobile terminal device received by the foreign agent at the source is classified into voice data and other data, and the voice data is buffered as described above. Therefore, for example, even in a mobile phone or the like capable of simultaneously performing Internet access and voice communication, there is an effect that deterioration of voice during handoff can be suppressed.

According to the present invention, the source foreign agent determines whether or not received data is voice data based on the type of session established by the mobile terminal device to be handed off. Therefore, there is an effect that audio data can be accurately classified.

According to the present invention, the source foreign agent determines whether or not the received data is voice data based on the type of the protocol. Therefore, session information is transmitted from the mobile terminal device. There is an effect that audio data can be accurately classified without acquiring it.

According to the present invention, the voice data received by the foreign agent at the movement source is stored in the buffer having a predetermined capacity, and when a predetermined closing transmission time has elapsed from the buffering start time, the voice data is stored in the buffer. Since all voice data is transferred to the mobile terminal device, the number of packets to be discarded can be reduced and voice deterioration at the time of handoff can be suppressed.

According to the present invention, the voice data received by the foreign agent at the movement source is stored in the buffer having a predetermined capacity, and it is determined whether or not a predetermined closing transmission time has elapsed for each voice data. Since the voice data whose transmission time has passed is transmitted to the mobile terminal device, the number of packets to be discarded can be reduced, and voice deterioration at the time of handoff can be suppressed.

According to the present invention, the audio data of the data received by the source foreign agent is stored in a buffer having a predetermined capacity, and the content of each buffered packet is linked to the same data as the packet. Since a new packet is generated by adding a header and the new packet is transferred, there is an effect that the number of transferred packets can be reduced and the load of the routing process can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an external agent according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating buffer management in an external agent according to the first embodiment.

FIG. 3 is an SDL diagram illustrating an operation of an external agent according to the second embodiment.

FIG. 4 is a diagram illustrating buffer management in an external agent according to the second embodiment.

FIG. 5 is an SDL diagram illustrating an operation of an external agent according to the third embodiment.

FIG. 6 is an SDL diagram illustrating an operation of an external agent according to the fourth embodiment.

FIG. 7 is an SDL diagram illustrating an operation of an external agent according to the fifth embodiment.

FIG. 8 is an SDL diagram illustrating an operation of an external agent according to the sixth embodiment.

FIG. 9 is a diagram illustrating transfer of data buffered in a foreign agent to a mobile terminal device after movement according to a seventh embodiment.

FIG. 10 is a diagram illustrating route optimization in the conventional MobileIP.

FIG. 11 is a diagram illustrating a conventional smooth handoff method.

FIG. 12 is a diagram illustrating buffer management in a conventional smooth handoff method.

FIG. 13 is a diagram illustrating transfer of buffered data to a mobile terminal device in a conventional smooth handoff method.

[Explanation of symbols]

1 mobile terminal device, 5-1 and 5-2 foreign agent, 11 CPU (buffer management means, data classification means), 16 network interface (reception means,
Transmission / reception means).

Continued on the front page F-term (reference)

Claims (12)

[Claims] An external agent for buffering data addressed to the mobile terminal device when the mobile terminal device moves and performs handoff, and transfers the buffered data to the mobile terminal device via another foreign agent to which the mobile terminal device moves. A receiving unit for receiving data addressed to the mobile terminal device; and storing the data received by the receiving unit in a buffer having a predetermined capacity, and new data after the buffer is filled with the data. A buffer management unit that, when received, selects data to be discarded so that discarded data becomes discontinuous in time series, discards the selected data from the buffer, and stores the new data in the buffer. And an external agent. 2. A data classification means for classifying data addressed to a mobile terminal device received by a reception means into voice data and other data, and a buffer management means stores the voice data in the buffer. The external agent according to claim 1, wherein: 3. The data classification means, based on the type of session established by the mobile terminal device to be handed off,
3. The external agent according to claim 2, wherein it is determined whether or not the data received by the receiving unit is voice data. 4. The external agent according to claim 2, wherein the data classification means determines whether or not the data received by the receiving means is voice data, based on a type of the protocol. 5. The voice data is Voice over I
The external agent according to any one of claims 1 to 4, wherein the external agent is audio data of P. 6. When a mobile terminal device moves and is handed off, a foreign agent of a source buffers data addressed to the mobile terminal device and transfers the buffered data to the mobile terminal device via a foreign agent of a destination. In the smooth handoff method of transferring, storing data received by a foreign agent of a movement source in a buffer having a predetermined capacity; and discarding data when new data is received after the buffer is filled with the data. Selecting data to be discarded so as to be discontinuous in time series, and discarding the selected data from the buffer and storing the new data in the buffer. Smooth handoff method. 7. When the mobile terminal moves and hands off, the mobile terminal buffers data addressed to the mobile terminal, and upon receiving a transfer request, transfers the buffered data to the mobile terminal via another foreign agent to which the mobile terminal moves. In the external agent for transferring to the device, transmitting / receiving means for transmitting / receiving data, and storing audio data received by the transmitting / receiving means in a buffer having a predetermined capacity, and a predetermined closing transmission time has elapsed from a buffering start time. The external agent, further comprising: buffer management means for transferring all voice data stored in the buffer to the mobile terminal device via the transmission / reception means. 8. When the mobile terminal device moves and is handed off, the source foreign agent buffers data addressed to the mobile terminal device, and upon receiving a transfer request, transfers the buffered data via the destination foreign agent. In the smooth handoff method of transferring to the mobile terminal device, the step of storing the voice data received by the foreign agent of the movement source in a buffer of a predetermined capacity, and when a predetermined close-out transmission time has elapsed from the buffering start time, Transferring all the audio data stored in the buffer to the mobile terminal device. 9. When the mobile terminal moves and hands off, the mobile terminal buffers data addressed to the mobile terminal, and upon receiving a transfer request, transfers the buffered data to the mobile terminal via another foreign agent at the destination. In the external agent for transferring to the device, transmitting / receiving means for transmitting / receiving data, and storing the audio data received by the transmitting / receiving means in a buffer having a predetermined capacity, and determining whether a predetermined closing transmission time has elapsed for each audio data. A buffer management unit for determining whether or not the voice data has passed the predetermined part-time transmission time toward the mobile terminal device via the transmission / reception unit. 10. When the mobile terminal device moves and is handed off, the source foreign agent buffers data addressed to the mobile terminal device, and upon receiving a transfer request, transfers the buffered data to the destination foreign agent via the destination foreign agent. Storing the voice data received by the foreign agent of the movement source in a buffer having a predetermined capacity, and determining whether a predetermined closing transmission time has elapsed for each voice data. And transferring the voice data for which the predetermined close-out transmission time has elapsed to the mobile terminal device. 11. When a mobile terminal device moves and is handed off, data addressed to the mobile terminal device is buffered,
Upon receiving the transfer request, an external agent for transferring the buffered data to the mobile terminal device via another foreign agent of the movement destination includes: a transmitting / receiving unit for transmitting / receiving data; , A new packet is generated by adding the same header as the packet to the concatenation of the contents of each buffered packet, and the new packet is transmitted via the transmitting / receiving means. An external agent, comprising: buffer management means for transferring. 12. When the mobile terminal device moves and is handed off, the source foreign agent buffers data addressed to the mobile terminal device, and upon receiving a transfer request, transfers the buffered data via the destination foreign agent. Storing the packets received by the foreign agent of the movement source in a buffer having a predetermined capacity; and connecting the contents of each buffered packet to the same as the packets. And generating a new packet by adding the header of (1), and transferring the new packet.