KR100949280B1 - Interface buffer control method during handover in network interface - Google Patents

Abstract

An interface buffer control method for handover according to the present invention is a multimode terminal having a plurality of network interface units and a common buffer for storing data transmitted from an upper IP layer to each of the network interface units. Transmitting the data stored in the buffer to a previously set buffer of the first network interface unit and transmitting the data to a receiving terminal; When performing a handover operation according to a predetermined handover policy, copying data stored in the common buffer and transmitting data to buffers of the plurality of network interface units; And when the handover is completed, transmitting data to the newly set buffer of the second network interface unit, and transmitting data to the receiving terminal through the corresponding second network.

Description

Method for controlling interface buffer during hand-over in network interface

The present invention relates to an interface buffer control method, and more particularly, to an interface buffer control method for minimizing packet loss occurring during handover between networks, that is, between network interface cards, in a multimode terminal equipped with a plurality of network interface cards. It is about.

In general, a multimode terminal having two or more network interface functions selects the most suitable network among the currently connectable networks according to a predetermined policy and performs communication.

In such a multi-mode terminal, a plurality of network interface cards are mounted, and in a region where a plurality of networks are mixed, data transfer between the network interfaces causes handover between network technologies, that is, handover between heterogeneous networks frequently. do.

1 is a system connection diagram for explaining data transmission in a state where a plurality of general network service areas overlap.

In FIG. 1, the first terminal 114, which is a multi-mode terminal, is equipped with a respective network interface card in an area where, for example, the areas 112 and 116 of each network of 802.16 and 802.11 overlap each other. The data transmitted from the first terminal 114 is relayed to the base station (BS) 110 or the access point (AP) 116, and access router (AR) 108 to connect the first terminal 114 to the network. And home agent (HA) 106 and access network and public Internet 104 and 102 to second terminal 100.

In this case, when the first terminal 114 is currently using the 802.16 network 112 and enters the 802.11 network 116 according to a specific handover policy based on a decrease in transmission / reception sensitivity through the corresponding network, the 802.16 network Handover to an 802.11 network is performed.

Since the first terminal 114 performs data communication through the 802.16 network, the data being transmitted / received exists in the buffer of the previous 802.16 network interface card before performing the handover to the 802.11 network. In the case of such data, since the user can no longer use the 802.16 network interface for data communication after the handover to the 802.11 network, the data temporarily stored in the 802.16 network buffer is inevitably lost.

2 is a view for explaining the buffer structure of a conventional multi-mode terminal.

For example, the structure of the multi-mode terminal is equipped with 802.16 and 802.11 network interface cards, and each network interface card includes a first buffer 20 and a second buffer 22, and a corresponding buffer is used to transmit and receive data. It is used as a temporary storage place.

When the terminal performs a handover to another network during data communication, that is, when switching from 802.16 to an 802.11 network interface card, data stored in the first buffer 20 of the previous network interface is lost. Even if the data is transmitted wirelessly through the network interface without being lost, the data is not transmitted to the receiver terminal because it is already out of range of the network.

Therefore, as described above, when the terminal transmits data, a large number of hands are lost because packet loss during handover between networks causes not only data loss due to handover delay time but also data existing in the buffer 20 of the previous network interface. It will cause over performance degradation.

This problem occurs due to the conventional data processing method of allocating a buffer for each network interface in the first terminal 114. The problem occurs only when the first terminal 114 is the sender side. This is because, when the first terminal 114 is the receiver side, the received terminal can process the received data even if the data in the corresponding buffer performs a handover to the 802.11 network.

There is a need for a method of controlling a buffer to solve a problem of data loss transmitted during handover of a terminal in such a redundant network and to transmit data more efficiently.

SUMMARY OF THE INVENTION An object of the present invention is to provide a buffer control method in a multi-mode terminal on a transmitting side that prevents packet loss by controlling a common buffer included in the terminal in a heterogeneous network handover.

The interface buffer control method at the time of handover in the multi-mode terminal according to the present invention for achieving the above object,

A multi-mode terminal having a plurality of network interface units and a common buffer for storing data transmitted from an upper IP layer to the respective network interface units, comprising: a first set of data stored in the common buffer in advance; Transmitting data to a buffer of a network interface unit and transmitting the data to a receiving terminal; When performing a handover operation according to a predetermined handover policy, copying data stored in the common buffer and transmitting data to buffers of the plurality of network interface units; And when the handover is completed, transmitting data to the newly set buffer of the second network interface unit, and transmitting data to the receiving terminal through the corresponding second network.

In addition, the interface buffer control method during handover according to the present invention,

In the multi-mode terminal device having a plurality of network interface unit and a common buffer for storing data transmitted from the upper IP layer to each of the network interface unit,

Transmitting the data stored in the common buffer to a previously set buffer of the first network interface unit and transmitting the data to a receiving terminal;

Retransmitting data stored in a buffer of a first network interface unit to the common buffer when the handover is operated and completed according to a predetermined handover policy; And

And transmitting the data stored in the common buffer to the newly set buffer of the second network interface unit during handover, and transmitting the data to the receiving terminal through the corresponding second network.

The data received and retransmitted from the first network interface unit in the common buffer may be processed as the highest priority among the data stored in the common buffer and transmitted to the newly set second network interface unit buffer.

 In addition, the header of the packet of data received and retransmitted from the first network interface unit in the common buffer is modified to a header transmitted from the newly set second network interface unit.

According to the present invention, the transmitting terminal copies data that may be lost in a heterogeneous network handover from a common buffer and simultaneously transmits the data to other network interface units or reprocesses the data transmitted before the handover. By retransmitting to the work interface unit, the data packet is prevented from being lost and the data is stably transmitted.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

In the embodiment of the present invention, it is assumed that the multi-mode terminal is equipped with an 802.16 network interface card and an 802.11 network interface card, that is, two network interfaces. In addition, it is assumed that the 802.16 network and the 802.11 network are constructed as shown in FIG. 1.

As shown in FIG. 1, the 802.16 network and the 802.11 network have some overlapping service areas, and it is assumed that the terminal communicates with the receiver as a sender during handover between the two networks.

3 is a block diagram illustrating the structure of an extended multi-mode terminal according to the present invention.

In the structure of the multi-mode terminal of the present invention, a buffer exists separately for each network interface card, and the network interface buffers 32 and 34 have a common data buffer 30 according to the Internet protocol when transmitting data to the network interface buffers 32 and 34. All data goes through a common buffer before going from the upper IP layer to the network interface.

The common buffer 30 transmits the data to the buffer 32 of the currently available network interface in the order of data accumulated in the buffer, and the transmitted data is transmitted to the corresponding receiving terminal through the network interface. By providing a common buffer 30 as described above, it is possible to control the overall data transmission and reception by transmitting the data to a specific network interface used by the multi-mode terminal.

In this way, the multi-mode terminal can minimize data loss that may occur during the process of switching the network interface during handover.

The common buffer 30 described above has an advantage of reducing data loss that may occur during handover by managing all data transmitted and received at the multi-mode terminal at once.

However, even when the extended multi-mode terminal switches the network interface during handover, data that has already been transferred from the common data buffer 30 to the previous network interface is lost.

That is, even when the extended multi-mode terminal has a common data buffer 30, during handover, data is stored in the buffer 32 of the first network interface card before handover as shown in FIG. 4A. After the over is completed, the data stored in the common buffer 30 is transferred to the buffer 34 of the second network interface card as shown in FIG. 4B. Accordingly, there is a problem in that data transmitted to the buffer 32 just before the completion of the handover is not transmitted and is lost.

In order to solve this problem, a process of reprocessing the data existing in the buffer 32 of the previous first network interface card is required. In the present invention, two buffer control methods will be described with respect to a method of reprocessing data.

5A to 5C are diagrams for describing an exemplary embodiment in which a buffer is controlled using data copy during handover according to the present invention.

 The multi-mode terminal is a method for copying the data existing in the common buffer 50 at the time of handover, and transfers the data to all network interfaces mounted in the terminal. Although the structure of the extended multi-mode terminal is the same, different reference numerals will be given for convenience of description.

5A shows a state before handover, in which an extended multimode terminal currently transmits data through an 802.16 network, and data in a common buffer 50 is transferred only to the buffer 52 of the 802.16 network interface card. . 5B shows that the terminal is performing a handover to the 802.11 network, in which data in the common buffer 50 is transferred to the buffer 52 of the 802.16 network interface card and also to the buffer 54 of the 802.11 network interface card. do.

The transferred data is transmitted to the receiver terminal through the 802.16 network and the 802.11 network, and FIG. 5C transmits data only to the buffer 54 of the switched network interface card as a state after the handover is completed.

The above-described method has the advantage that data loss is prevented, but the multi-mode terminal copies each data in the common buffer 50 during the handover so that not only the buffer 52 of the 802.16 network interface card but also the buffer 54 of the 802.11 network interface card can be used. Since data is also delivered by), data copy overhead and duplicated data may arrive at the receiver terminal.

6A and 6C are flowcharts of main data in an extended multimode terminal for explaining a second embodiment of the present invention.

6A, which is a second embodiment of the present invention to solve the problem of data duplication reception in the processing method of FIG. 5, shows an operation state in which an extended multi-mode terminal transmits data through an 802.16 network, and has a common buffer. Data in 60 is only transferred to the buffer 62 of the 802.16 network interface card.

FIG. 6B illustrates a state immediately after the handover operation is completed in the 802.11 network. When data that is not transmitted to the buffer 62 of the 802.16 network interface card exists, the corresponding data is transmitted to the common buffer 60 again. The retransmitted data is processed with the highest priority in the common buffer 60, and the processed data is transmitted back to the corresponding receiver terminal through the buffer 64 of the 802.11 network interface card.

In this case, when extracting the data from the common buffer 60, an additional operation is required. Since all headers (IP, MAC, etc.) of the data packet are already completed, the MAC and IP headers must be modified and transmitted again in order to transmit data through the new network interface.

Therefore, in the common buffer 60, the header information and the like are modified and transferred to the buffer 64 of the 802.11 network interface card, so that data can be transmitted to the receiver terminal without loss. Although the method of this second embodiment has an overhead of reassembling data as compared with the above-described first embodiment, it causes problems such as duplicate data reception at the receiver terminal, thereby preventing loss of transmitted data. can do.

Although a preferred embodiment of the present invention has been described in detail above, those skilled in the art to which the present invention pertains may make various changes without departing from the spirit and scope of the invention as defined in the appended claims. It will be appreciated that modifications or variations may be made. Therefore, changes in the future embodiments of the present invention will not be able to escape the technology of the present invention.

1 is a system diagram for explaining data transmission in a state where network service areas overlap.

2 is a view for explaining the buffer structure of a conventional multi-mode terminal.

3 is a diagram for explaining a main structure of an extended multi-mode terminal according to the present invention.

4A and 4B are diagrams for describing the flow of data during handover in FIG. 3.

 5A to 5C are diagrams for describing an embodiment of controlling a buffer according to the present invention.

6A and 6C are flowcharts of main data in an extended multimode terminal for explaining a second embodiment of the present invention.

Claims (4)

A multi-mode terminal having a plurality of network interface units and a common buffer for storing data transmitted from the upper IP layer to each of the network interface units, Transmitting the data stored in the common buffer to a previously set buffer of the first network interface unit and transmitting the data to a receiving terminal; When performing a handover operation according to a predetermined handover policy, copying data stored in the common buffer and transmitting data to buffers of the plurality of network interface units; And When the handover is completed, transmitting data to the newly set buffer of the second network interface unit, and transmitting the data to the receiving terminal through the second network. How to control interface buffers. A multi-mode terminal having a plurality of network interface units and a common buffer for storing data transmitted from the upper IP layer to each of the network interface units, Transmitting the data stored in the common buffer to a previously set buffer of the first network interface unit and transmitting the data to a receiving terminal; Retransmitting data stored in a buffer of a first network interface unit to the common buffer when the handover is operated and completed according to a predetermined handover policy; And Transmitting the data stored in the common buffer to a newly set buffer of the second network interface unit during handover, and transmitting the data to the receiving terminal through the corresponding second network. Override interface buffer control method. 3. The method of claim 2, wherein the data received from the first network interface unit in the common buffer and retransmitted are processed as the highest priority among data stored in the common buffer and transmitted to the newly set second network interface unit. Interface buffer control method during handover in a multimode terminal. 4. The handover of a multimode terminal of claim 3, wherein a header of a packet of data received and retransmitted from the first network interface unit in the common buffer is modified to a header transmitted from the newly set second network interface unit. How to control the interface buffer of a city.

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