KR100452053B1 - Method for transmitting data packet of mobile hosts within a cellular ip access network - Google Patents

Abstract

The present invention relates to a data packet forwarding method of a mobile host in a cellular IP access network. When the data packet is delivered from a lower base station or a mobile host, the method comprises: checking whether a destination address entry exists in the path cache after updating the path cache; Comparing the sub-base station indicated by the destination address item with the sub-base station on which the data packet is raised when the address item exists; and when the sub base station indicated by the destination address item and the sub base station on which the data packet is raised are not the same. Forwarding to the base station indicated by the destination address item, and replicating the data packet and sending the duplicated dummy data packet to the upper base station, and the lower base station and data packet indicated by the destination address item does not exist or indicated by the destination address item Raised child And transmitting the data packet to a higher base station in the case where the base station is the same, and processing the data packet at the base station located between the gateways at the cross base station by delivering the data in the optimal path when communication between users connected to the cellular IP access network is made. There is an advantage in reducing the resources for doing so, and improving the stability of the network.

Description

METHOD FOR TRANSMITTING DATA PACKET OF MOBILE HOSTS WITHIN A CELLULAR IP ACCESS NETWORK}

The present invention relates to a data packet delivery method of a mobile host in a cellular IP access network. More particularly, when the access network is configured using cellular IP, an optimal path is selected when the communication between different users located in the access network occurs. The present invention relates to a data packet forwarding method of a mobile host in a cellular IP access network which can reduce network resources and improve reliability.

A computer network on the Internet consists of three elements: a host, a physical network to which the hosts are connected, and a router that interconnects the physical networks. These components are constructed by physical networks using local and wide area network data link technologies. Support as possible.

Transmission Control Protocol / Internet Protocol (abbreviated as TCP / IP) on the Internet is a collection of protocols that define how data is exchanged in a computer network, of which IP is a connectionless best effort data transfer service. It is an internet protocol to provide. Since IP was designed for wired and fixed-located hosts at the time of design, when a mobile host uses IP, movement of a host in a packet-switched mobile network implies a change of Internet address.

However, if the Internet address is changed, the session already connected must be disconnected and a new session must be established with the changed address. The re-establishment of these sessions was the biggest reason for the lack of smooth service using the wireless Internet.

To solve this problem, the Internet Engineering Task Force (IETF) designated Mobile IP as a Request for Comments (RFC) standard in 1996. Mobile IP does not require a change in the address given to the mobile host even if the mobile host moves during data communication, and thus provides a foundation for supporting communication without disconnection of the session even during the move.

However, in case of using Mobile IP, the quality of wireless internet is deteriorated when the mobile host frequently moves the cell boundary. As a countermeasure, the University of Colombia proposed the cellular IP protocol to IETF in 1999. .

Cellular IP is a protocol for preventing the degradation of the wireless Internet generated by Mobile IP when a mobile host moves within a certain area called cellular IP access network. Cellular IP access network is connected to one gateway and several base stations. It is composed.

In the cellular IP access network, a special base station called a gateway is located at the point where the cellular IP access network is connected to the Internet. The gateway is located at the top of the cellular IP access network from a network architectural point of view. The gateway and the base station are wired, and each base station has two functions of communicating with the mobile host through an air interface and delivering IP packets to other base stations. In order to deliver the IP packet to the final receiver, each base station relies on its cache information to determine the next base station to hand over the IP packet to.

Packet forwarding in a cellular IP access network can be classified into an uplink forwarding process and a downlink forwarding process.

The uplink forwarding process is a process in which a packet sent from a mobile host is delivered to a gateway, and all packets having a mobile host as a sender are first delivered to a gateway. Base stations located on the path through which the packet is delivered to the gateway, upon receiving the packet, update the route cache and paging cache managed by the base station and send the packet to the higher base station. Finally, when the packet reaches the gateway, the upstream process ends. The gateway and all base stations have a route cache, which contains information about the next base station to go through when trying to deliver a packet to a destination. The paging cache only exists at gateways and base stations designated by the administrator.

On the other hand, the downlink delivery process is a packet forwarding method applied to packets having a mobile host as a receiver. The base station receiving the packet destined for the mobile host as the final destination wirelessly connected to the cellular IP access network selects the next base station using the route cache information and the paging cache information managed by each base station, and delivers the packet. The base station receiving the packet selects the next base station in the same process. By repeating this method, the packet is finally delivered to the mobile host that is the destination.

FIG. 1 is a diagram illustrating a configuration of a general cellular IP access network. FIG. 2 is a diagram illustrating a path through which data is transmitted when communication between mobile hosts connected to a cellular IP access network is performed according to the prior art. In the case of sending a data packet to another mobile host Y (20), the path b is transmitted.

As shown here, in the cellular IP access network, one gateway 1 and a plurality of base stations 2 to 9 are connected by wire. The gateway 1 is a base station located at the point where the cellular IP access network and the Internet a are connected.

The gateway 1 and each of the base stations 2 to 9 all have one path cache 10 to 18. The path cache contains data packet transmission information for forwarding the data packet to the mobile hosts 19 and 20.

As mentioned above, the process of transferring data from the mobile host X 19 to the gateway 1 is referred to as an uplink forwarding process, and the process of transferring data from the gateway 1 to the mobile host Y 20 is downward. This is called the delivery process.

First, the uplink forwarding process, in order for the mobile host X 19 to transfer data to the mobile host Y 20, the mobile host X 19 generates an IP data packet, in which the mobile host is the source of the data packet. It contains the address of X (19) and the address of mobile host Y (20) which is the final destination.

Data packets made at mobile host X 19 are delivered wirelessly to base station S 9. The base station S 9 analyzes the IP header of the received data packet to detect the source address of the data packet, and updates the validity time of the item related to X which is the source of the packet in its path cache 18 to update the cache item. Make sure it stays valid.

Base station S (9) forwards the data packet to base station O (5), which is its upper base station, to send data to the gateway. The base station O 5 also updates its path cache 14 in the same manner, and then transfers the data packet to the base station N 4, which is a higher base station.

If this process is repeated, the data packet is delivered to the gateway 1 and the data packet delivery by the uplink delivery process is terminated.

Thereafter, the data packet is delivered to the mobile host Y 20 by the downlink transmission process, and the process is as follows.

The gateway 1 checks whether information about the mobile host Y 20 that is the destination of the data packet exists in its path cache 10. In the example, since the data is transmitted to the base station A 2 in order to transmit the data packet to the mobile host Y 20 in the path cache 10, the data packet is transferred to the base station A 2. After receiving the data packet, the base station A 2 transfers the data packet to the base station M 3 based on its path cache information.

Repeating this process, the data packet is finally delivered to the mobile host Y (20).

In the data packet forwarding method according to the related art as described above, it can be seen that the paths between the gateway 1 and the base station N 4 overlap. This is because all packets sent from the mobile host are forwarded to the gateway regardless of the destination address in the forwarding process.

In other words, if a mobile host user using the wireless Internet based on cellular IP wants to send data to another user in his cellular IP network, the cellular IP protocol rules all data packets to the gateway first and then again. It is transmitted to the other party through the opposite path. The base station located at the point where the uplink path and the downlink cross each other is called a cross base station. When communication is performed between users located in the same cellular IP access network, the paths between the cross base stations and the gateways overlap.

Accordingly, there is a problem in that the base station located in the redundant path is a waste of resources unnecessarily to reduce the efficiency of the wireless Internet.

In addition, even though there is a path connecting the sender to the receiver regardless of whether the upper base stations of the cross base station are operated from the gateway, in the existing cellular IP, when the base station located between the upper base stations of the cross base station is stopped in the existing cellular IP. There was a problem that the data is not delivered at all.

The present invention has been proposed to solve such a problem of the prior art, by selecting the shortest path that does not overlap the path when data transmission between users connected to the same cellular IP access network to transfer the data, network resources and base stations The purpose is to improve the stability of the access network while saving resources.

In the cellular IP access network according to the present invention for realizing the above object, a data packet forwarding method of a mobile host includes a destination address entry in the path cache after updating a path cache when a data packet is transmitted from a lower base station or a mobile host. A second step of checking whether the first base station indicated by the destination address item and the lower base station indicated by the data packet when the destination address item exists, and a lower base station indicated by the destination address item; A third step of transmitting the data packet to a lower base station indicated by a destination address item when the lower base station on which the data packet is raised is not the same, and transmitting the duplicated dummy data packet to the upper base station after the data packet is duplicated; The destination address entry does not exist Or if the lower base station indicated by the destination address item and the lower base station on which the data packet is raised are the same, transferring the data packet to a higher base station.

1 is an exemplary view showing the configuration of a general cellular IP access network,

2 is a diagram illustrating a path through which data is transmitted when communication is performed between mobile hosts connected to a cellular IP access network according to the prior art;

3 is an exemplary diagram illustrating a path through which data is transmitted when communication is performed between mobile hosts connected to a cellular IP access network according to the present invention;

4 is a flowchart illustrating a data packet forwarding method of a mobile host in a cellular IP access network according to the present invention.

<Explanation of symbols for the main parts of the drawings>

1: Gateway

2, 3, 4, 5, 6, 7, 8, 9: base station

10, 11, 12, 13, 14, 15, 16, 17, 18: route cache

19, 20: mobile host

a: internet

b: prior art data transmission path

c: optimal data transfer path of the present invention

d: dummy data transfer path of the present invention

There may be a plurality of embodiments of the present invention. Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings. This embodiment allows for a better understanding of the objects, features and advantages of the present invention.

3 is a diagram illustrating a configuration of a cellular IP access network for applying a data packet delivery method of a mobile host in a cellular IP access network according to the present invention, and a path through which data is transmitted when communication between mobile hosts connected to the cellular IP access network is performed. .

As shown in the drawing, the cellular IP access network includes one gateway 1 and a plurality of base stations 2 to 9 connected by wire, and the gateway 1 and each of the base stations 2 to 9 are all connected to one cell. It has path caches 10-18. The path cache has information indicating in which direction the base station should transmit the data packet in order to deliver the data packet to the mobile hosts 19 and 20.

For example, when base station M 3 receives a data packet destined for mobile host Y 20 from base station A 2, base station M 3 searches its path cache 12. The path cache 12 contains information for forwarding the data packet to the base station N 4 in order to deliver the data packet to the mobile host Y 20. Base station M (3) thus passes the data packet to base station N (4).

When the base station N (4) receives the data packet, it scans its path cache 13 in the same way as the base station M (3) did, and checks whether there is information about the mobile host Y (20) as the destination. Since the path cache 13 has information to forward the data packet to the base station R 8 in order to deliver the data packet to the mobile host Y 20, the data is transferred to the base station R 8.

When the base station R 8 receives the data packet, it checks its path cache 17, and the data transmission is completed by transmitting the data packet to the mobile host Y 20 according to the information of the path cache 17. .

The form of the access network illustrated in FIG. 3 is just one example, and the present invention can be applied to all types of cellular IP access networks. In addition, the gateway 1 and each of the base stations 2 to 9 may have a paging cache if necessary, and in case of having a paging cache, the route cache is first searched for the destination address of the data packet. Check if this exists. If the destination address entry does not exist in the path cache, the second step is to check whether the destination address entry exists in the paging cache. In the upstream delivery process of the present invention, since the basic structure and the function of the path cache and the paging cache are the same, the paging cache is omitted in the drawings for convenience of description. Therefore, the present invention also applies when each base station has both a path cache and a paging cache. All procedures related to the paging cache are performed only when the base station has a paging cache, and the procedure is omitted when the base station does not have a paging cache.

FIG. 4 is a flowchart illustrating a data packet delivery method of a mobile host in a cellular IP access network according to the present invention. FIG. When updating the path cache and paging cache that it owns, it checks whether the destination address entry of the data packet exists in the path cache or the paging cache, and then shows the process of determining the forwarding direction of the data packet.

As described above, the data packet forwarding method of the present invention includes steps 111 to 123 of checking whether a destination address item exists in the path cache after updating the path cache and the paging cache when the data packet is delivered from the lower base station, and the path. Checking whether there is a destination address entry in the paging cache (131 to 133) if the destination address entry does not exist in the cache, and when the destination address entry exists in the path cache or paging cache, Comparing the lower base stations on which the data packets are raised (141 to 143), and when the lower base stations indicated by the destination address items and the lower base stations on which the data packets are raised are not the same, deliver the data packets to the lower base stations indicated by the destination address items. Step 151, and after the data packet is copied Step (153 to 155) of sending the data packet to the upper base station, and if the destination base station does not exist in the path cache and the paging cache, or the lower base station indicated by the destination address entry and the lower base station on which the data packet is uploaded are the same. It is carried out in step 161 of transmitting to a higher base station.

Since the dummy data packet to be replicated according to the present invention is the same as the original data, the sender and receiver addresses recorded in the header of the dummy data packet are the same as the sender and receiver addresses of the original data packet, respectively, and the reason for sending the dummy data packet to the upper base station. Is for updating a path cache and a paging cache held by higher base stations. In addition, when the gateway receives the data packet, if the lower base station that has passed the data packet to the gateway and the next lower base station to pass through to transfer the data packet to the mobile host are identical, the data packet is divided into dummy data packets and then erased.

A method of transmitting data packets of a mobile host in a cellular IP access network according to the present invention configured as described above will be described in detail below with reference to the exemplary diagram of FIG. 3.

First, when mobile host X 19 wishes to transmit data to mobile host Y 20, mobile host X 19 generates a data packet and forwards it to base station S 9 (111).

After receiving the data packet, base station S (9) updates the route cache (18) for mobile host X (19), which is the sender, to see if there is a lower base station capable of going to mobile host Y (20), the final destination of the data packet. Examine the path cache 18 (113, 121).

In the example, since only the information about X is included in the path cache 18, the base station S 9 transfers the data packet to the base station O 5, which is a higher base station (161).

The base station O 5 updates the route cache 14 for the mobile host X 19, which is the source of the data packet, and checks whether there is an entry in the route cache 14 for the mobile host Y 20, which is the destination address. (113, 121).

In the example, since there is no entry for the Y 20 in the path cache 14, the data packet is forwarded to the base station N 4, which is a higher base station (161).

When base station N (4) receives the data packet, it checks whether there is a lower base station capable of going to mobile host Y (20), which is the final destination of the data packet, while updating the path cache (13) for mobile host X (19) as the originator (113, 121).

In the example, there is an entry for Y (20) in the path cache 13, and the lower base station indicated by the path cache 13 is the base station R (8), which is different from the lower base station O (5) from which the data packet is raised. The data packet is forwarded to the base station R (8), which is a lower base station indicated by the destination address item (151).

At the same time, base station N (4) generates a dummy data packet that is a duplicate of the data packet and sends it to base station M (3), which is a higher base station (153, 155).

The base station R 8 forwards the received data packet back to the mobile host Y 20.

On the other hand, the base station M (3) receiving the dummy data packet, as in the case of receiving the normal data packet, while updating the path cache 12, whether there is an entry for the destination Y (20) contained in the dummy data packet? Check (113, 121, 123).

In the example, there is an entry for the destination address Y (20) in the path cache 12, but the base station 13 to which the lower base station indicated by this entry forwarded the dummy data packet to the base station N (13) to the base station M (12). Same as (141, 143). Therefore, the dummy data packet is forwarded to the base station A 2 which is the upper base station 161.

The base station A 2 transfers the dummy data packet to the gateway 1 by the same method as that of the base station M 3.

The gateway 1 receiving the dummy data packet updates the path cache 10 for the mobile host X 19 that is the sender of the dummy data packet, and there is an entry for the mobile host Y 20 that is the receiver of the dummy data packet. Check if it is.

In the example, the corresponding item exists in the path cache 10, and the lower base station indicated by this item is the base station A (2). Since the base station A 2 is the same as the lower base station that delivered the dummy data packet to the gateway, the base station A 2 erases the dummy data packet.

Through such a series of processes, the data packet is transmitted from the mobile host X 19 to the mobile host Y 20 via the optimal data transfer path c, and at the same time, the dummy data packet passes through the dummy data transfer path d. The route cache is updated in the gateway 1 and the upper base stations 2 and 3 while passing through to the gateway.

In the above description, but limited to one embodiment of the present invention, it is obvious that the technology of the present invention can be easily modified by those skilled in the art. Such modified embodiments should be included in the technical spirit described in the claims of the present invention.

As described above, the present invention has the following advantages by transferring data in an optimal path when communication is performed between users connected to the same cellular IP access network.

First, it is possible to save resources for processing data packets at base stations located between gateways at cross base stations. This is because the conventional path method uses redundant paths from the sender to the gateway through the receiver, whereas the path used in the present invention uses the optimal path between the sender and the receiver not through the gateway.

Second, improve the stability of the network. In FIG. 1, assuming data transmission using mobile host X 19 as a sender and mobile host Y 20 as a receiver, data is conventionally transmitted using the data transfer path b of FIG. 2. Therefore, when a failure occurs in the gateway 1, the base station A (2), or the base station M (3), the data transmission path is blocked, so that data transmission is interrupted. However, in the present invention, data is transmitted through the optimal data transfer path (c) of FIG. 3, and this path (c) does not go through the gateway (1), the base station A (2), or the base station M (3). Data transfer is possible even if interrupted.

Claims (5)

In a cellular IP access network consisting of a mobile host and a gateway and a plurality of base stations, a method of delivering a data packet of a corresponding base station for delivering a data packet transmitted by a mobile host to a receiver, A first step of checking whether a destination address entry exists in the path cache after updating the path cache when a data packet is transmitted from a lower base station or the mobile host; A second step of comparing the lower base station indicated by the destination address item and the lower base station on which the data packet is present when the destination address item exists; When the lower base station indicated by the destination address item and the lower base station on which the data packet is raised are not the same, the data packet is transferred to the lower base station indicated by the destination address item, and after the data packet is duplicated, the copied dummy data packet Sending a to a higher base station, And a fourth step of delivering the data packet to a higher base station when the lower base station indicated by the destination address item does not exist or the lower base station indicated by the destination address item is the same. Data packet forwarding method. The method of claim 1, wherein the fourth step The gateway, which has received the data packet, erases the data packet when the lower base station on which the data packet is raised and the next lower base station to pass through to transfer the data packet to the mobile host are identical. Data packet forwarding method of mobile host in IP access network. The method of claim 1, wherein the first step Update the paging cache with the route cache, and if the destination address entry does not exist in the route cache, check whether a destination address entry exists in the paging cache, and then perform the second to fourth steps. A method of forwarding data packets to a mobile host in a cellular IP access network. The method of claim 1, wherein the third step And transmitting and receiving information recorded in the header of the dummy data packet in the same manner as the sender and receiver information of the data packet. The method of claim 1, The pseudo data packet transmitted to the upper base station is used to update a path cache or a paging cache of the upper base station.