JP2002223467A - Dynamic delay ACK control device in mobile terminal device and dynamic delay ACK control method in mobile terminal device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To eliminate duplicate ACK response due to packet reception order inversion when temporary route duplication occurs when the route optimization function of Mobile IP is applied at the time of handover, This provides a dynamic delay ACK control device in a mobile terminal device, which can eliminate unnecessary packet retransmission in a server and can improve the overall communication throughput. SOLUTION: When an occurrence of handover is detected by a link state inspection processing section 32, a delayed ACK start / end specifying section 34 is provided.
Sets a delayed ACK response period for confirming that packets have been received from the base station apparatus in sequence number order. If the period is set at the time of packet reception, if the sequence number of the received packet is detected by the functions of the reception sequence number inspection unit 40 and the timer processing unit 44 to be not the sequence number to be received, the duplicated sequence number Delay ACK to prevent transmission of ACK to base station apparatus
Perform control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to Mobile I
In a mobile communication network to which a route optimization function (described later) of the P (Internet Protocol) protocol is applied, when a handover is performed when a mobile terminal device moves between base station devices, an appropriate communication state is set. TECHNICAL FIELD The present invention relates to a dynamic delay ACK control device in a mobile terminal device that performs control for holding and a dynamic delay ACK control method in the mobile terminal device.

[0002]

2. Description of the Related Art The Mobile IP protocol is an I
R at ETF (Internet Engineering Task Force)
It is standardized as FC (Request for Comments) 2002. According to the technology of the Mobile IP protocol, no matter where the mobile terminal device is connected on the Internet, the permanent mobile device assigned to the mobile terminal device ｛the home address of the mobile terminal device ｛the permanent mobile terminal device is assigned to the mobile terminal device. By transmitting the packet to the IP (Internet Protocol) address #, the packet is transmitted to the destination of the mobile terminal device.

In a mobile communication network that controls the location management of a mobile terminal device using the Mobile IP protocol, a packet transferred from a server on the transmitting side to the mobile terminal device via a base station device is always a home agent ( HA). The HA is a router that stores current location information for the mobile terminal device.

[0004] Since the route passes through the HA, the route becomes redundant,
HA will be loaded. For this reason, the destination address is cached (stored in the high-speed storage device) by the server,
It is effective to perform route optimization by tunneling, that is, by embedding a multicast packet in a unicast packet, encapsulating the packet, and transferring the packet directly to a destination communication terminal device.

However, the binding update message for notifying the destination address to the server is transferred from the HA to the server after the HA receives the registration request from the mobile terminal device for security reasons. In this case, there is a delay before the data is transferred to the new destination address by the cache, and during that time, the data is transferred to the address before the transfer, which causes a packet loss due to a packet routing error.

[0006] To solve this, Mobile I
As the route optimization function of P, there is a function of notifying the destination address from the destination foreign agent (FA) to the FA before movement. FA is a mobile node (mobile terminal device)
Is a router on the network visited by the mobile node to provide a route service to the mobile node while is registered.

By the route optimization function, a packet transmitted to a pre-movement address due to a delay in updating the binding cache is re-tunneled from the pre-movement FA to the destination FA and delivered to the destination.

[0008]

In the above conventional mobile communication network, a TCP (Transmission Control Protocol) is used by using a route optimization function of Mobile IP.
ol) When the communication is performed, when the mobile terminal device switches the FA due to the base station device handover, the server (transmission node) → FA before movement → FA of destination → FA of mobile terminal (mobile) Node) and two types of communication paths, that is, a server, a destination FA, and a mobile terminal device, are temporarily generated.

For this reason, the TC following the latter shorter path
The P-packet overtakes the TCP packet on the former route and arrives at the mobile terminal first, so that the receiving order inversion of the sequence number of the TCP packet occurs. That is, in the mobile terminal device, a phenomenon that the order of receiving packets is reversed occurs.

At this time, in the mobile terminal device, when the TCP function receives the TCP packet directly transferred to the destination FA on the latter route, the TCP function still transmits the TCP packet from the FA before the transfer.
It interprets that the CP packet has been lost and duplicates ACK (Ack
response (send) to the server. When the server receives three packets of the duplicate ACK, the server retransmits the packet which is considered to have been lost by the high-speed retransmission algorithm.

The congestion window size is reduced by TCP congestion control due to the order inversion phenomenon, and the transfer amount is reduced. This lowers the overall throughput of the communication.

Therefore, the present invention provides a method for controlling the Mo
When the route optimization function of the “bile IP” is applied, it is possible to eliminate the response of the duplicate ACK due to the reversal of the packet reception order when the temporary route duplication occurs, thereby eliminating unnecessary packet retransmission at the server. It is an object of the present invention to provide a dynamic delay ACK control device in a mobile terminal device and a dynamic delay ACK control method in the mobile terminal device that can improve the overall communication throughput.

[0013]

In order to solve the above-mentioned problems, a dynamic delay ACK control device in a mobile terminal device according to the present invention comprises a mobile terminal of a mobile communication network to which a route optimization function of a communication protocol is applied. A dynamic delay ACK control device in a device, comprising: detecting means for detecting the occurrence of handover when moving between base station devices; and when detecting the occurrence of the handover, a predetermined period of time from the occurrence of the handover. First setting means for setting a delay ACK response period indicating that the delay A has been set, and the first setting means when receiving a packet from the base station apparatus.
First to check if the CK response period has been set
And if the reception sequence number, which is the number of the packet received from the base station apparatus, is not the sequence number to be received originally when the delayed ACK response period is set by the inspection, Control means for performing a dynamic delay ACK control for preventing the transmission of the number packet to the base station apparatus.

When the route control of the packet transfer to the mobile terminal device using the binding cache of the route optimization function in the communication protocol (Mobile IP protocol) is performed, the route is temporarily doubled by handover. Therefore, the order of the sequence numbers of the packets received by the mobile terminal device is reversed. Therefore, since it is expected that the order will be reversed for a certain period after the handover has occurred, a delayed ACK response period is set.
Even if the sequence number reverses during this setting,
Due to the dynamic delay ACK control, a packet having a duplicate sequence number (a packet with an ACK response inserted) is not transmitted to the server via the base station device.

Further, in the dynamic delay ACK control device in the mobile terminal device according to the present invention, the control means checks the coincidence / mismatch between the reception sequence number and the sequence number to be originally received. And the second
Setting the first flag indicating that the execution period of the dynamic delay ACK control is being performed when the inspection results by the inspection means do not match, and activating the first flag by setting the first flag; A timer that counts the time to release the flag, and a second timer that is activated by the setting of the first flag and that counts the time of transmission timing of an ACK response in the dynamic delay ACK control Preferably, a processing means is provided.

During the period in which the order is reversed after the occurrence of the handover, the dynamic delay ACK control can be performed by maintaining the setting of the first flag by the first timer,
At the time of the control, the ACK response can be transmitted at the transmission timing instructed by the timing operation of the second timer.

Further, in the dynamic delay ACK control device in the mobile terminal device according to the present invention, the second checking means updates a maximum reception sequence number in accordance with the reception sequence number when setting the delay ACK response period. Then, after the sequence number to be received next is updated when the received sequence number matches the sequence number to be originally received, if the received sequence number matches the maximum received sequence number, It is preferable that the second timer is stopped and the first flag is released.

When the reception sequence number is larger than the maximum reception sequence number, the maximum reception sequence number is updated (changed) to the reception sequence number. In other words, if it is small, it is left as it is. Thereafter, if the reception sequence number matches the maximum reception sequence number, the dynamic delay A
Since there is no need to perform CK control, the first and second timers are stopped and the first flag is released. As a result, the dynamic delay ACK control ends, and normal ACK response processing is performed.

Further, in the dynamic delay ACK control device in the mobile terminal device according to the present invention, when the second check means determines that the received sequence number does not match the maximum received sequence number, It is preferable that the apparatus further comprises second setting means for setting a second flag indicating that all packets having a sequence number smaller than the sequence number have been received.

In the delayed ACK response period, if the second flag is set, it is possible to recognize that all packets having a sequence number smaller than the received sequence number have been received. It can be carried out.

In order to solve the above problem, a dynamic delay ACK control method in a mobile terminal device according to the present invention provides a mobile terminal device in a mobile communication network to which a route optimization function of a communication protocol is applied. A method for controlling dynamic delay ACK in a device, comprising: a detection step of detecting occurrence of a handover when moving between base station devices; A first setting step of setting a delayed ACK response period indicating a fixed period of time, and the first setting step includes the step of setting the delay A when a packet is received from the base station apparatus.
First to check if the CK response period has been set
And when the delayed ACK response period is set in the first inspection step, the reception sequence number, which is the number of the packet received from the base station device, is not the sequence number to be originally received. And a control step of performing a dynamic delay ACK control to prevent a packet having an overlapping sequence number from being transmitted to the base station apparatus.

When a route control of packet transfer to a mobile terminal device using a binding cache of a route optimization function in a communication protocol (Mobile IP protocol) is performed, a route is temporarily doubled by handover. Therefore, the order of the sequence numbers of the packets received by the mobile terminal device is reversed. Therefore, since it is expected that the order will be reversed for a certain period after the handover has occurred, a delayed ACK response period is set.
Even if the sequence number reverses during this setting,
Due to the dynamic delay ACK control, a packet having a duplicate sequence number (a packet with an ACK response inserted) is not transmitted to the server via the base station device.

Further, in the dynamic delay ACK control method in the mobile terminal device according to the present invention, the control step includes:
A second checking step of checking whether the reception sequence number matches a sequence number to be originally received,
When the test results of the second test step do not match, a first flag indicating that the dynamic delay ACK control is being executed is set, and the first flag is activated by the setting of the first flag. A first timer processing step for measuring a time for releasing the first flag;
A second timer processing step for activating by setting the first flag and for measuring a time of transmission timing of an ACK response in the dynamic delay ACK control. Is preferred.

During the period in which the order is reversed after the occurrence of the handover, the dynamic delay ACK control can be performed by maintaining the setting of the first flag by the first timer,
At the time of the control, the ACK response can be transmitted at the transmission timing instructed by the timing operation of the second timer.

Further, in the dynamic delay ACK control method for a mobile terminal device according to the present invention, the second checking step updates a maximum reception sequence number in accordance with the reception sequence number when setting the delay ACK response period. And
After updating the sequence number to be received next when the received sequence number matches the sequence number to be originally received, if the received sequence number matches the maximum received sequence number, the first and second sequences are updated. It is preferable to stop the first timer and release the first flag.

When the reception sequence number is larger than the maximum reception sequence number, the maximum reception sequence number is updated (changed) to the reception sequence number. In other words, if it is small, it is left as it is. Thereafter, if the reception sequence number matches the maximum reception sequence number, the dynamic delay A
Since there is no need to perform CK control, the first and second timers are stopped and the first flag is released. As a result, the dynamic delay ACK control ends, and normal ACK response processing is performed.

[0027] In the dynamic delay ACK control method in the mobile terminal apparatus according to the present invention, when it is determined in the second check step that the reception sequence number does not match the maximum reception sequence number, the reception is performed. Preferably, the method further comprises a second setting step of setting a second flag indicating that all packets having a sequence number smaller than the sequence number have been received.

In the delayed ACK response period, if the second flag is set, it is possible to recognize that all packets having a sequence number smaller than the reception sequence number have been received. It can be carried out.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A dynamic delay ACK control device in a mobile terminal according to an embodiment of the present invention will be described with reference to the drawings.

First, the configuration of the dynamic delay ACK control device in the mobile terminal device according to the present embodiment will be described. FIG. 1 is a configuration diagram of a dynamic delay ACK control device in a mobile terminal device according to the present embodiment.

As shown in FIG. 1, the dynamic delay ACK control device 10 in the mobile terminal device according to this embodiment includes a radio data link processing unit 12 and a radio link control unit 14.
, A transport protocol processing unit 16 and a network protocol processing unit 18.

The wireless data link processing unit 12 includes a beacon frame processing unit 20, a BS (BaseStation) list update processing unit 22, an optimal BS processing unit 24, and a synchronization processing unit 26.
, A wireless link data processing unit 28, and a BS list unit 30.

The radio link control unit 14 includes a link state inspection processing unit (detection means) 32, a delay ACK start / end designation unit (first setting means) 34, and a timer processing unit 36. I have.

The transport protocol processing unit 16
A delayed ACK checking unit (first checking unit) 38, a reception sequence number checking unit 40 (second checking unit),
K setting section 42 (second setting means) and timer processing section 44
(Timing processing means) and a TCP packet reception processing unit 46
And an ACK transmission processing unit 48.
The receiving sequence number checking unit 40 and the timer processing unit 44 constitute a control unit described in claims.

The network protocol processing unit 18
It comprises a P protocol processing unit 50.

The beacon frame processing unit 20, the synchronization processing unit 26, and the wireless link data processing unit 28
It is connected to a physical layer 52 that performs data communication processing on a wireless communication line (wireless link). Hereinafter, each component will be described in detail.

The beacon frame processing unit 20 performs a process of extracting a beacon signal from a base station device (not shown) received by the mobile terminal device via the physical layer 52.

[0038] The BS list update processing section 22 stores information included in the beacon signal extracted by the beacon frame processing section 20 in the BS list section 30 in association with the base station apparatus ID (Identifier).

The optimum BS processing unit 24 selects the optimum BS (base station device) from the BS list unit 30 for performing appropriate communication in accordance with the information of the beacon signal from the BS list update processing unit 22.

The synchronization processor 26 communicates with the BS selected by the optimum BS processor 24 via the physical layer 52 to establish synchronization.

The wireless link data processing unit 28 transmits a TCP packet (sometimes simply expressed as a packet) from the BS to which synchronization has been established by the synchronization processing unit 26.
2 and the IP protocol processing unit 50
ACK response data from the BS via the physical layer 52
Send to

The IP protocol processing unit 50 performs processing such as addressing and routing, which are predetermined IP protocol processing, on the packet from the wireless link data processing unit 28 and the data of the ACK response from the ACK transmission processing unit 48. I do.

The link state inspection processing unit 32 periodically monitors the BS list unit 30 and, when detecting the occurrence of the base station apparatus handover, notifies the delay ACK start / end designation unit 34 of the occurrence.

Upon receiving the notification of the occurrence of the handover, the delayed ACK start / end designation unit 34 receives the notification of the occurrence of the handover, that is, a predetermined period of time after the occurrence of the handover, that is, AC
Delayed ACK, which is the time to perform a particular process on the K response
The dynamic delay ACK flag is set to "1" to start the response period. Further, a delay ACK start / end designation unit 3
4 is a delay AC after a specific time c corresponding to the certain period.
In order to end the K response period, a timer for setting the dynamic delay ACK flag to “0” is set in the timer processing unit 36. With this setting, the dynamic delay ACK flag becomes “0” after the specific time c, and the delay ACK response period ends. The specific time c corresponding to the certain period is considered in consideration of the delay time of the wireless section, the delay time due to the detour path of the packet, and the like. It is determined to include a certain time.

Upon receiving the TCP packet reception notification from the TCP packet reception processing unit 46, the delayed ACK check unit 38 inquires of the delayed ACK start / end designation unit 34 whether or not it is a delayed ACK response period. As a result, the dynamic delay A
If the CK flag is “0”, that is, if it is not the delayed ACK response period, the ACK transmission processing unit 48 is requested to perform normal ACK response processing. If the dynamic delay ACK flag is a delayed ACK response period of “1”, the reception sequence number check unit 40 is requested to check the reception sequence number that is the sequence number of the received TCP packet.

The reception sequence number checking unit 40 compares the maximum reception sequence number (the maximum number of the packets received so far) held in advance with the reception sequence number. Change to the reception sequence number. Further, the reception sequence number is compared with the sequence number to be received next (the number obtained by adding 1 to the sequence number continuously received so far). The number is updated, and if they do not match, the timer processing unit 44 is requested to perform timer processing for starting the dynamic delay ACK control. The dynamic delay ACK control is a control for preventing a TCP packet having a duplicate sequence number from being transmitted to the BS.

Further, the reception sequence number checking section 40
If the reception sequence number matches the maximum reception sequence number, the timer processing unit 44 is requested to perform a timer process for terminating the dynamic delay ACK control.
The CK setting unit 42 is requested to make settings for delayed ACK transmission. Delayed ACK transmission refers to A in dynamic delay ACK control.
Indicates transmission of a CK response.

When a timer process for starting the dynamic delay ACK control is requested from the reception sequence number checking unit 40, the timer processing unit 44 checks whether the hard timer flag (first flag) is set. As a result, if it is not set to “0”, the hard timer flag is set to “1”. The hard timer flag is a flag for defining a period during which the dynamic delay ACK control is performed when a handover occurs, and when “1”, indicates that the dynamic delay ACK control is being performed.

The timer processing unit 44 sets a hard timer (first timer) for setting the hard timer flag to “0” after a specific time a, and executes a soft timer process described later after the specific time b. A soft timer (second timer) to be set. Furthermore, at the end of the soft timer process,
After a specific time b, the soft timer is set. That is, the soft timer repeatedly counts the time interval of the specific time b. Here, the specific time a is an execution period of the dynamic delay ACK control, and is defined by a limit at which an ACK response must be made on TCP. The specific time b is ACK
It is time to make a trigger for a response. The soft timer process is a process for responding to the ACK for the packet having the largest sequence number among the packets that have already been received and whose sequence numbers are continuously aligned, using the timer for the specific time b as a trigger.

Further, when a timer process for terminating the dynamic delay ACK control is requested from the reception sequence number checking unit 40, the timer processing unit 44 cancels the setting of the soft and hard timers and sets the hard timer flag to “ Set to "0". When a hard timeout occurs, the soft timer is canceled and the hard timer flag is set to “0”.
, And requests the delay ACK setting unit 42 to set a delay ACK flag (second flag). The delayed ACK flag is a flag indicating that all packets having a sequence number smaller than the reception sequence number have been received, and when "1", all packets having a sequence number smaller than the reception sequence number have been received. It shows that.

The delay ACK setting unit 42 receives a setting request for delay ACK transmission from the reception sequence number checking unit 40,
That is, when a request for setting the delayed ACK flag is received,
If the delay ACK flag is not set to “0”, it is set to “1”. Further, when a request to release the delayed ACK flag is received, the delay ACK flag is set to “0”.

Next, the operation of the dynamic delay ACK control device 10 in the mobile terminal device according to the present embodiment will be described, and the dynamic delay AC control device according to the embodiment of the present invention will be described.
The K control method will be described. FIG. 2 is a diagram illustrating a procedure for performing processing of the dynamic delay ACK control in the dynamic delay ACK control device in the mobile terminal device according to the present embodiment.

In step S1 shown in FIG. 2, when the mobile terminal device receives a TCP packet from the BS,
In step S2, the delay ACK check unit 38 checks whether the dynamic delay ACK flag is set to “1”.

Here, the wireless link state inspection processing for setting the dynamic delay ACK flag will be described with reference to FIG. FIG. 3 is a diagram showing a procedure for performing a wireless link state inspection process in the dynamic delay ACK control device in the mobile terminal device according to the present embodiment.

In step 21 shown in FIG. 3, the BS list unit 30 is monitored by the link state inspection processing unit 32, and when the occurrence of the base station apparatus handover is detected, the occurrence of the handover is delayed by ACK.
The start / end designation unit 34 is notified.

In the delayed ACK start / end specifying unit 34 that has received this notification, the dynamic delay ACK flag is set to "1" in step S22, and the dynamic delay ACK flag is released after a specified time c seconds, ie, " A timer for setting “0” is set in the timer processing unit 36. With this setting, the dynamic delay ACK flag is cleared after the specified time c seconds.

If the dynamic delay ACK flag is not set to "1" as a result of the check at step S2 in FIG. 2, that is, if the flag is "0", no handover has occurred, so the delay ACK check unit 38 Requests the ACK transmission processing unit 48 for normal ACK response processing.

That is, as a normal TCP packet receiving process, the sequence number to be received next is updated in step S3, data is added to the socket buffer in step S4, and in step S5,
A flag for immediately responding with ACK is set, and T
The CP packet transmission processing routine is called. That is, a packet field of the TCP packet is created,
Output processing of a TCP packet (TCP output processing) is performed. Thereby, the ACK response is inserted into the TCP packet and transmitted to the server (not shown) via the BS. After this processing, the process returns to step S1.

On the other hand, if the dynamic delay ACK flag is set to "1" as a result of the check in step S2, it means that the delay ACK response period at the time of handover has occurred. The unit 40 updates the maximum reception sequence number.

That is, the maximum reception sequence number is compared with the reception sequence number. As a result, when the reception sequence number is large, the maximum reception sequence number is changed to the reception sequence number. For example, when the maximum reception sequence number is "6" and the reception sequence number is "9", the maximum reception sequence number is changed to "9". If the reception sequence number is smaller than "6", the maximum reception sequence number is not changed.

Next, in step S7, the reception sequence number checking section 40 determines whether or not the reception sequence number matches the sequence number to be received next. As a result of the determination, if they do not match, the timer processing unit 44 is requested to perform a timer process for performing the dynamic delay ACK control. For example, the sequence number to be received next is “5”.
In this case, if the reception sequence number is "6", there is no match, so the timer processing is requested.

In response to this request, the timer processing unit 44
In step S8, it is checked whether the hard timer flag is set to "1". As a result,
If "1" has been set, the process returns to step S1.

If it is not set to "0", the hard timer flag is set to "1" for executing the dynamic delay ACK control in step S9, and the hard timer flag is set to "0" after the specified time a seconds. The timer to be set is set,
At the same time, the soft timer processing (tcp softtim
A timer to execute o) is set. After this setting, the process returns to step S1.

On the other hand, as a result of the determination in step S7, it is assumed that the reception sequence number matches the sequence number to be received next. For example, when returning to step S1 from any of steps S5, S8, and S9, it is assumed that the packet having the sequence number “5” is received by TCP packet reception, and then the determination process of step S7 is reached. In this case, since the sequence number "5" to be received next matches the sequence number "5", the sequence number to be received next is "6" by the reception sequence number checking unit 40 in step S10. Will be updated to

Thereafter, in step S11, the reception sequence number checking section 40 determines whether the reception sequence number matches the maximum reception sequence number. For example, if the reception sequence number is “5” and the maximum reception sequence number is “6”, the determination results do not match. Therefore, the reception sequence number inspection unit 40 sends the delay ACK setting unit 42 Processing is requested.

The delayed ACK setting unit 42 receiving this request
Then, in step S12, it is determined whether or not the delay ACK flag is “0” which is not set. If the result of this determination is that it is set to "1" instead of "0", the process returns to step S1.

If it is "0", in step S13,
After the delay ACK flag is set to “1” by the delay ACK setting unit 42, the process returns to step S1.

On the other hand, as a result of the determination in step S11, it is assumed that the reception sequence number matches the maximum reception sequence number. For example, steps S5, S8, S9, S12,
When returning to step S1 from any of S13, TCP
It is assumed that, after the packet having the sequence number “6” is received in the packet reception, the determination process of step S11 has been reached. In this case, the reception sequence number “6” matches the maximum reception sequence number “6”.
A timer process for ending the K control is requested.

In response to this request, the timer processing unit 44
In step S14, the setting of the soft and hard timers is canceled, and the hard timer flag is set to "0". As a result, the dynamic delay ACK control is terminated, and the processing in step S5 described above is executed.

Next, the hard timer processing in the dynamic delay ACK control in step S9 will be described with reference to FIG. FIG. 4 is a diagram showing a procedure for performing a hard timer process in the dynamic delay ACK control device in the mobile terminal device according to the present embodiment.

In this hard timer process, in step S31 shown in FIG. 4, the setting of the soft timer is canceled after the specified time a seconds by the timer processing unit 44.
The hard timer flag is set to “0”. This ends the dynamic delay ACK control. Further, step S3
In 2, the delay ACK flag is set to "0" by the delay ACK setting unit 42, and in step S33, the flag for immediately responding to the ACK is set to "1".
The CK transmission processing unit 48 executes a TCP output process.

Next, the soft timer processing in the dynamic delay ACK control in step S9 will be described with reference to FIG. FIG. 5 is a diagram illustrating a procedure for performing a soft timer process in the dynamic delay ACK control device in the mobile terminal device according to the present embodiment.

In this soft timer process, in step S41 shown in FIG. 5, the reception sequence number checking section 40 checks whether the delay ACK flag is set to "1". As a result, if it is set to "1", the delay ACK setting unit 42 changes the delay ACK flag to "0" which is not set in step S42, and sets a flag for immediately responding ACK in step S43. After it is set to “1” and the delay ACK counter is incremented, in step S44, ACK
The TCP output processing is executed by the transmission processing unit 48.

Then, in step S45, after a specified time b seconds in the timer processing section 44, steps S41 to S4
A timer for executing the soft timer process (tcp softtimo) of No. 4 is set. After this setting, the process returns to step S41. If the delay ACK flag is not set to “0” in step S41, the process of step S45 is immediately executed.

Next, the operation and effect of the dynamic delay ACK control device in the mobile terminal device according to the present embodiment will be described. In the dynamic delay ACK control device 10 in the mobile terminal device according to the present embodiment, the link state inspection processing unit 32 detects occurrence of handover when moving between base station devices, and specifies the delay ACK start / end designation unit 34. so,
Upon detecting the occurrence of the handover, a delayed ACK response period for confirming that the packets have been received from the base station apparatus in order of the sequence number is set. Delay ACK checker 38
Then, at the time of receiving a packet from the base station apparatus, it is checked whether or not a delayed ACK response period has been set in the delayed ACK start / end designating section 34. Sequence number checker 4
0, when the control unit configured by the timer processing unit 44 detects that the reception sequence number, which is the number of the packet received from the base station device, is not the sequence number to be originally received, the packet having the duplicate sequence number is deleted. A dynamic delay ACK control for preventing transmission to the base station device is performed.

Therefore, the communication protocol (Mobile)
When the route control of the packet transfer to the mobile terminal device using the binding cache of the route optimization function in the IP protocol) is performed, the route is temporarily doubled by the handover, and therefore, the route is received by the mobile terminal device. It is expected that the order of the sequence numbers of the packets will be reversed, and the order will be reversed for a certain period after the handover occurs. Therefore, a delayed ACK response period is set as described above. Even if the order of the sequence numbers is reversed during this setting, packets with duplicate sequence numbers (packets with an ACK response inserted) due to dynamic delay ACK control
Is not transmitted to the server via the base station device.

After a handover occurs, a delayed ACK response period is started.
Since the response is not transmitted, the server does not needlessly retransmit the packet by the high-speed retransmission algorithm. This makes it possible to improve the overall communication throughput.

In the dynamic delay ACK control, since an ACK including the largest sequence number among consecutive sequence numbers received by the soft timer process is responded, a server timeout due to an ACK reception delay during order inversion is avoided. It is possible to do. Further, since the present embodiment is a new function of the mobile terminal device, the function of the present embodiment can be realized without changing the function of the server (transmission side), and accordingly, it can be easily implemented.

Further, in the mobile terminal device according to the present embodiment, when the delayed ACK response period is set, the maximum reception sequence number is updated according to the reception sequence number, and the reception sequence number matches the sequence number to be received. Sometimes, after updating the sequence number to be received next, if the reception sequence number matches the maximum reception sequence number, the hardware timer and the soft timer are cancelled, and the hard timer flag is released, thereby enabling dynamic delay. A
The CK control can be ended. As a result, in a communication state in which the reception inversion does not occur, there is an effect that the dynamic delay ACK control is terminated and a normal ACK response process can be performed.

Further, in the dynamic delay ACK control device in the mobile terminal device according to the present embodiment, when it is determined that the reception sequence number does not match the maximum reception sequence number, the sequence number of the sequence number smaller than the reception sequence number is determined. By setting the delayed ACK flag indicating that all packets have been received, it can be recognized that all packets having a sequence number smaller than the received sequence number have been received. As a result, even in the delayed ACK response period, if all packets having a sequence number smaller than the reception sequence number have been received, transmission processing of an immediate ACK response can be performed after timeout.

[0081]

According to the present invention, a dynamic delay ACK control device in a mobile terminal device and a dynamic delay AC in a mobile terminal device are provided.
The K control method detects the occurrence of a handover, sets a delayed ACK response period at the time of this detection, checks whether a delayed ACK response period is set when a packet is received from the base station apparatus, When the period is set, if the reception sequence number, which is the number of the packet received from the base station device, is not the sequence number to be originally received, the packet with the duplicate sequence number should not be transmitted to the base station device. By performing the dynamic delay ACK control, even if the order of the sequence numbers is reversed, packets with duplicate sequence numbers (packets with an ACK response inserted) are not transmitted to the server via the base station device. As a result, the server does not needlessly retransmit the packet by the high-speed retransmission algorithm. Thus, there is an effect that the throughput of the entire communication can be improved.

Further, the dynamic delay ACK control device in the mobile terminal device and the dynamic delay ACK control method in the mobile terminal device according to the present invention provide a dynamic delay ACK control method in which the received sequence number and the sequence number to be originally received do not match. Setting a first flag indicating execution of the ACK control, activating a first timer for measuring a time for canceling the setting of the first flag,
By activating the second timer that measures the time of the transmission timing of the ACK response in the dynamic delay ACK control, the first timer is activated during the period in which the order inversion occurs after the handover occurs.
The dynamic delay ACK control can be performed by maintaining the setting of the first flag with the timer of
The ACK response can be transmitted at the transmission timing indicated by the timing operation of the second timer. As a result, since an ACK including a sequence number received continuously and periodically is returned, there is an effect that a server timeout due to an ACK reception delay during order inversion can be avoided.

Further, according to the dynamic delay ACK control device in the mobile terminal device and the dynamic delay ACK control method in the mobile terminal device of the present invention, when the delay ACK response period is set, the maximum reception sequence number is updated according to the reception sequence number. And updating the next sequence number to be received when the received sequence number matches the sequence number to be originally received, and when the received sequence number matches the maximum received sequence number, the first and second timers Is stopped and the first flag is cleared, so that if the reception sequence number is larger than the maximum reception sequence number, the maximum reception sequence number is updated (changed) to the reception sequence number.
If the reception sequence number matches the maximum reception sequence number, the dynamic delay ACK control is terminated by stopping the first and second timers and releasing the first flag. be able to.

As a result, if there is a communication state in which the reception inversion does not occur, there is an effect that the dynamic delay ACK control is terminated and the normal ACK response processing can be performed.

Further, according to the dynamic delay ACK control device in the mobile terminal device and the dynamic delay ACK control method in the mobile terminal device of the present invention, when a mismatch between the reception sequence number and the maximum reception sequence number is determined, By setting the second flag indicating that all packets having a sequence number smaller than the sequence number have been received, it can be recognized that all packets having a sequence number smaller than the received sequence number have been received.

As a result, even during the delayed ACK response period, if all packets having a sequence number smaller than the reception sequence number have been received, the AC
The transmission process of the K response can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a dynamic delay ACK control device in a mobile terminal device.

FIG. 2 is a diagram showing a procedure for performing processing of dynamic delay ACK control.

FIG. 3 is a diagram showing a procedure for performing a wireless link state inspection process.

FIG. 4 is a diagram showing a procedure for performing a hard timer process.

FIG. 5 is a diagram showing a procedure for performing a soft timer process.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Dynamic delay ACK control device, 12 ... Wireless data link processing part, 14 ... Wireless link control part, 16 ... Transport protocol processing part, 18 ... Network protocol processing part, 20 ... Beacon frame processing part, 22 ... BS list Update processing unit, 24: optimal BS processing unit, 26: synchronization processing unit, 28: wireless link data processing unit, 30: B
S list part, 32 ... link state inspection processing part, 34 ... delay ACK start / end designation part, 36, 44 ... timer processing part,
38 ... Delayed ACK checker, 40 ... Receive sequence number checker, 42 ... Delayed ACK setter, 46 ... TCP packet reception processor, 48 ... ACK transmission processor, 50 ... IP protocol processor, 52 ... Physical layer

Claims (8)

[Claims] 1. A dynamic delay ACK control device in a mobile terminal device of a mobile communication network to which a route optimization function of a communication protocol is applied, a detecting means for detecting occurrence of handover when moving between base station devices. A first setting unit configured to set a delayed ACK response period indicating a predetermined period from the occurrence of the handover upon detection of the occurrence of the handover, and upon receiving a packet from the base station device, First checking means for checking whether the delayed ACK response time is set in the first setting means, and receiving from the base station apparatus when the delayed ACK response time is set by the check. If the reception sequence number, which is the packet number, is not the sequence number that should be received, the packet with the duplicate sequence number Dynamic Delay ACK controller in a mobile terminal device, wherein a and a control means for performing dynamic delay ACK control to avoid sending to the base station apparatus. 2. The control device according to claim 1, wherein the control unit checks whether the reception sequence number matches a sequence number to be originally received. Setting a first flag indicating that the dynamic delay ACK control is being executed, and starting the first flag by setting the first flag and measuring a time for releasing the first flag. And a timer processing means having a timer and a second timer which is activated by the setting of the first flag and measures the time of transmission timing of an ACK response in the dynamic delay ACK control. A dynamic delay ACK control device in the mobile terminal device according to claim 1. 3. The method according to claim 2, wherein the second checking unit is configured to perform the delay ACK.
Updating the maximum reception sequence number according to the reception sequence number at the time of setting a response period, and updating the next sequence number to be received next when the reception sequence number matches the sequence number to be originally received. The mobile terminal device according to claim 2, wherein when the number matches the maximum reception sequence number, the first and second timers are stopped and the first flag is released. Delay ACK control device. 4. When all the packets having a sequence number smaller than the reception sequence number are received when the second check means determines that the reception sequence number does not match the maximum reception sequence number. 4. The dynamic delay ACK control device in a mobile terminal device according to claim 3, further comprising second setting means for setting a second flag indicating the second flag. 5. A dynamic delay ACK control method in a mobile terminal device of a mobile communication network to which a route optimization function of a communication protocol is applied, wherein occurrence of a handover during movement between base stations is detected. A first setting step of setting a delayed ACK response period indicating a predetermined period from the occurrence of the handover when the occurrence of the handover is detected in the detecting step; A first checking step of checking whether the delayed ACK response period is set at the time of receiving a packet from the base station device in the setting step, and the delayed ACK response period being set in the first checking step. The receiving sequence, which is the number of the packet received from the base station device. A control step of performing dynamic delay ACK control for preventing a packet having a duplicate sequence number from being transmitted to the base station apparatus if the number is not a sequence number to be originally received. In the dynamic delay ACK control method. 6. The control step comprises: a second check step for checking whether the received sequence number matches a sequence number to be originally received; and a case where the check results obtained by the second check step do not match. Setting a first flag indicating that the dynamic delay ACK control is being executed, and starting the first flag by setting the first flag and measuring a time for releasing the first flag. A timer processing step;
A second timer processing step of activating according to the setting of the first flag and measuring a time of transmission timing of an ACK response in the dynamic delay ACK control. Item 6. A dynamic delay ACK control method in the mobile terminal device according to item 5. 7. The method according to claim 7, wherein the second checking step includes the step of
When the CK response period is set, the maximum reception sequence number is updated according to the reception sequence number, and when the reception sequence number matches the sequence number to be originally received, the sequence number to be received next is updated. 7. The method according to claim 6, wherein when the sequence number matches the maximum reception sequence number, the first and second timers are stopped and the first flag is released.
6. The dynamic delay ACK control method in the mobile terminal device according to item 1. 8. When all the packets having a sequence number smaller than the received sequence number are received when it is determined in the second check step that the received sequence number does not match the maximum received sequence number. 8. The method according to claim 7, further comprising a second setting step of setting a second flag indicating the following.