KR20120033971A - Apparatus and method for performing handover between heterogeneous radio networks, and system thereof - Google Patents

Abstract

PURPOSE: An apparatus and method for performing handover between heterogeneous radio networks and a system thereof are provided to prevent the disconnection of handover access while connection attempt. CONSTITUTION: A system transmits packet which is supposed to be transmitted from an existing data link layer through a tunnel(300). If the transmitting packet is an MIH(Media Independent Handover) or a handover packet, the system adds the transmitting packet to the MIH packet buffer or a bucket(310,330). If the transmitting packet is an application data packet, the system adds the transmitting packet as an application data packet buffer or bucket in order to enable the system perform transmitting(340).

Description

Apparatus and method for performing handover between heterogeneous wireless networks and system therefor {APPARATUS AND METHOD FOR PERFORMING HANDOVER BETWEEN HETEROGENEOUS RADIO NETWORKS, AND SYSTEM THEREOF}

TECHNICAL FIELD The present invention relates to wireless networks and, more particularly, to apparatus, methods and systems for performing handover from one wireless network to another.

Users of mobile devices such as phones, notepad computers, and tablelet computers typically want to access the Internet from a variety of locations. Large networks of publicly accessible WiFi hotspots or access points have evolved. In particular, in the case of mobile phones, users can move between APs while connected to the Internet. For example, this may occur during a Voice over IP (VoIP) call or when music or video is streaming. In other situations, handovers between different types of networks may occur. For example, even if a data connection is established using Wi-Fi, handover to a cellular data system such as 3G may be required.

Handover between different APs provided by different entities has a problem that data connection to the Internet may be dropped during the handover process.

Therefore, there is a need for a handover technique that prevents disconnection during handover.

The present invention proposes an apparatus, a method, and a system for preventing a connection disconnection from occurring during handover.

In order to solve the above problems, the method of the present invention is a method for performing a handover of a mobile device from a first wireless network to a second wireless network, wherein the mobile device is handed to an information server through the tunnel. And transmitting, by the mobile device, a handover data packet to the information server through another path, wherein the mobile device communicates with a server of a mobile IP (MIP) system through a tunnel. And an information server connected to the first and second wireless networks, the information server providing handover messages to the mobile device when performing a handover from the first wireless network to the second wireless network. Characterized in that.

In order to solve the above problems, an apparatus of the present invention is a mobile device that communicates via a first wireless network and a second wireless network, the server of the MIP (Mobile IP) system via a tunnel, and the first and the first And a mobile device coupled to an information server connected to two wireless networks, the mobile device transmitting a handover data packet to the information server through the tunnel and the other path, wherein the information server is configured to transmit the first server from the first wireless network. When performing a handover to a wireless network, characterized in that to provide handover messages to the mobile device.

Another method of the present invention for solving the above problems is, in the method for performing a handover of the mobile device from the first wireless network to the second wireless network, determining that the handover is imminent or in progress; And buffering data packets transmitted from the different mobile device, wherein the mobile device is connected to a server of a mobile IP (MIP) system through an tunnel and to an information server connected to the first and second wireless networks. The information server provides handover messages to the mobile device when performing the handover from the first wireless network to the second wireless network, wherein the handover data packets included in the data packets are application data packets. It is characterized in that it is transmitted in priority over these.

Another apparatus of the present invention for solving the above problems is a mobile device for communicating via a first wireless network and a second wireless network, the server of the MIP (Mobile IP) system through the tunnel, the first and And a mobile device coupled to an information server connected to second wireless networks, the mobile device determining whether a handover is imminent or ongoing and buffering data packets transmitted from the mobile device, wherein the information server comprises the first wireless network. Providing handover messages to the mobile device when performing a handover from the second wireless network to the second wireless network, wherein handover data packets included in the data packets are transmitted in preference to application data packets. .

Another method of the present invention for solving the above problems is a method for performing a handover of a mobile device from a first wireless network to a second wireless network, determining that the handover is imminent or in progress. And transmitting, at a server, handover data packets from the mobile device and buffering the handover data packets if the handover is imminent or in progress, wherein the mobile device transmits MIP (Mobile IP) through a tunnel. A server connected to the server of the system and to an information server connected to the first and second wireless networks, the information server to the mobile device when performing a handover from the first wireless network to the second wireless network. Providing handover messages.

Another device of the present invention for solving the above problems, in the server of the Mobile IP (MIP) system, connected to the mobile device through a tunnel, if the handover is determined to be impending or in progress, the mobile device The server for transmitting handover data packets and buffering the handover data packets, and the mobile device is connected with an information server connected with first and second wireless networks, the information server from the first wireless network. And providing handover messages to the mobile device when performing a handover to the second wireless network.

The present invention has the effect that the disconnection of the handover connection does not occur during the handover.

1 shows a prior art system using MIH.
2 illustrates a prior art system using both MIH and MIP.
Figure 3 is a block diagram of a system according to an embodiment of the present invention.
4 is a flowchart illustrating a handover in a system according to an embodiment of the present invention.
5 is a flowchart for performing a handover in a system according to an embodiment of the present invention.

To help with handover management, a system known as MIH (Media Independent Handover) has been developed. The system manages handover of data connections between different wireless data networks, such as Wi-Fi, WiMax, 3G or other cellular data networks. The system ensures seamless connectivity with the Internet when data connections change during handover.

1 is a schematic diagram of a MIH enable system. The mobile device 1 operating in the first position is assigned an IP address of a.b.c.d while connected via the Wi-Fi interface. Since the mobile device 1 is MIH capable, it performs MIH communication with the required MIH server 10 through the interface (A). While connected via the interface A, the user uses a video streaming application, such as a web browser, that has access to YouTube. The web browser establishes a session with the video streaming server 20 over the Internet. The server 20 then continues to transmit video data packets, via interface A, to the mobile device 1 having the IP address a.b.c.d. Since the MIH is enabled, the mobile device 1 can be directed to move to another interface B at some point. This may be due to a degraded signal condition. The device 1 is assigned a new IP address p.q.r.s via the new interface B. The new MIH server 10 'is different from the previous one and may be in a new location, but is not necessarily so. The mobile device performs registration via the new interface B as required in a known manner.

The problem with MIH, however, is that it does not maintain the mobile device's IP address. This means that the connection with the video streaming server 20 is lost due to the change of the IP address in the above situation. This is clearly annoying for the user since the user later needs to reset the session with the server 20.

A system has been developed to solve this problem known as MIP (Mobile IP, defined in RFC3344). The system provides a mobile device with a single IP address through a tunneling mechanism through heterogeneous air interfaces. This is accomplished by the Mobile IP server, which uses a data tunnel for communication with the mobile device and allows an invariant IP address to be associated with the mobile device. This situation is schematically illustrated in FIG. 2.

Here, the mobile device 101 is MIP and MIH enabled, and is connected to the MIP HA (Home Agent) 130 through the Wi-Fi interface (A), and then to the Internet and MIH servers 110. Using MIP HA, the mobile device 101 is associated with a constant home IP address x.y.z.w even though its actual IP address may change when moving between networks. Data packets destined for the mobile device are forwarded to the constant IP address and rerouted by HA 130, which always knows the mobile device's actual IP address.

In FIG. 2, the mobile device 101 is connected to the HA server 130 through a tunnel 131. The mobile device is coupled to a video streaming server 120 configured to stream video to the constant IP address x.y.z.w. The server 120 redirects all data packets to the mobile device 101 when the HA 130 needs it, so it does not need or know the actual IP address of the mobile device.

When the mobile device moves to a new position, the mobile device can be handed over to the new interface B. The new interface B may be a cellular data interface provided by the 3G system. The actual IP address associated with the mobile device is changed to p.q.r.s, but the data packets are routed through a new tunnel 132 established by the HA 130. Since the apparent IP address of the mobile device has not changed, data packets from the video server 120 are still provided to the mobile device, but the user does not notice the degradation of device performance due to handover. Indeed, the user may not be notified of the handover.

However, a problem with MIP systems using MIH is that, upon handover, the MIP HA sends packets over the old interface for some time until the MIP tunnel is properly established. During this period, high levels of packet loss are observed. Another problem is that handover occurs due to a decrease in signal strength. In prior art systems, the MIP tunnel needs to be stabilized before the MIH messages pass. Thus, the handover may take longer than the desired time.

Some techniques for solving the problems appearing during handover in these situations are presented below. It should be noted that the respective solutions may be employed alone or in combination where appropriate.

In the following various aspects of the present invention, it is noted that the basic hardware requirements of the system (ie mobile and fixed network elements) are the same as in the prior art. The method of operation will vary as described. Use of the same modified hardware in operation will help to ensure backward compatibility with prior art devices. Modifications to known hardware can be accomplished through proper programming or provision of appropriate customer hardware.

According to one embodiment of the first aspect of the present invention, it takes advantage of the fact that data packets can be transferred between the Internet and a MIP and MIH enabled mobile device via a MIP data tunnel or some other means. This is possible because the actual device IP address can be known to the MIH server. If this address is unknown, MIH discovery procedures can be used in a known manner to locate the server. FIG. 3 illustrates a basic system configuration different from FIG. 2 in that a separate communication path 233 is established between the mobile device 201 and the MIH server 210.

To implement this, MIH message packets can additionally be sent to the MIH servers via a path outside the data tunnel 231, so the handover process is entirely dependent on the MIP data tunnel set up completely to achieve handover. It is not. To this end, the mobile device may be adapted to send MIH handover messages to the MIH servers via another available path 233, which does not use the MIP tunnel 232 and does not transmit over the tunnel.

Transmitting to the MIH server outside the tunnel includes transmitting directly to the MIH server or through another intermediary device such as an additional server or router.

The first responding device (ie MIP HA 230 or MIH server 210) will provide an indication of the status of the handover process. Subsequent responses will be ignored as redundant.

If the MIP HA 230 completes the tunnel configuration faster than the MIH servers 210 can complete the handover, the MIH client will be able to complete the MIH MM and IS server through the tunnel 232 created on the new air interface. Start a new communication sequence with the group. The handover is considered complete only when the MIH client exchanges all message sets and a MIP tunnel is established as required by the MIH protocol.

If the MIH server 210 cannot complete the handover, the attempted handover is considered to have failed. As a result, a failure procedure commences with the next step of attempting handover on the preferred radio link. This process also involves resetting the MIP tunnel to the previous air interface and reestablishing possible additional communication with the MIH servers over the previous air link. These steps are very similar to the handover process itself. If these steps fail, the mobile device loses its connection with the servers, and all attempts to recover will be similar to normal mobile device power-on procedures.

When the MIH servers 210 complete the communication before the MIP tunnel 232 is created, the main thread of the application enters a standby state, and the MIP registration and tunnel setup with the HA server 210 are completed. waiting. If MIP registration is not possible over the new air interface, the device will abandon the new air interface and attempt a new handover to the next preferred air interface, or connect with MIH servers (except MIP HA). In idle mode, you can continue through the current interface. This guarantees a persistent connection, but not a constant IP address, which means that some applications may or may not work with a reduced feature set.

However, upon successful completion of the MIP registration, the MIH client may select whether to re-register with the MIH server again via the tunnel 232 established with the HA server. This allows all messages to be delivered via a single path and avoids unnecessary duplication. Applications can now run on the device with full IP transparency.

With this active redundancy in message delivery, more robust and reliable handovers can be achieved, resulting in an improved user experience.

Embodiments according to the second aspect of the present invention provide a mobile device that operates as described herein.

Embodiments according to the third aspect of the present invention provide a tangible computer readable medium for performing the method as described herein.

According to an embodiment of the fourth aspect of the invention, buffering is used to provide additional data security during handover. In this embodiment, data buffering is performed at the server side.

In the first embodiment of the fourth aspect, which is a server side solution, in the prior art, the MIP HA, which merely forwards the data packets to the intended mobile device without further checking, finds MIH packets in the data traffic destined for the particular user. . To this end, the HA searches for distinctive MIH signatures in the data packets. The HA performs a search by sniffing the MIH packet headers to find MIH handover related messages (candidate query / commit message). Detection of such handover related messages results in buffering activity, and all subsequent packets are stored as well as transmitted in the normal manner.

Initiation of buffering starts a timer, and ongoing buffering continues for a defined time. This time is chosen to be appropriate for special cases under the assumption that handover is imminent. The handover may have already failed, which means that new messages do not appear on the link, so a timer is needed. The timer duration can be selected in terms of the server's buffer capacity, which depends on the overall network load and / or how many other handovers are in progress. If less active handovers occur, more buffer space may be allocated. A typical buffer period can be 5 minutes, and in special cases it can be longer or shorter than this butter period if required.

When the HA receives a new registration message from a new Care of Address (CoA) from the same user over a new link, the timer starts and runs for a period of time, upon expiration of the timer, packets on the buffer are sent to the HA encapsulation engine. The HA encapsulation engine sends these to the mobile device. The encapsulation engine packages individual datagrams for transmission to the mobile device's CoA.

No further changes are required to the encapsulation engine, and other packets received from the HA that need to be sent to the mobile are treated as normal.

By buffering data packets for a particular user in this way, if a problem occurs during handover, the data packets can be retransmitted to the user when needed without being lost. Without buffering in the HA, if for some reason a problem occurs in the handover process, all data packets destined for a particular user may be lost.

If the handover completes successfully, the buffered data packets may be discarded and ongoing communication with the device may continue as usual.

Embodiments according to the fifth aspect of the present invention provide a mobile device that operates as described herein.

Embodiments according to the sixth aspect of the present invention provide a tangible computer readable medium for performing the method as described herein.

Embodiments according to the seventh aspect of the present invention apply data buffering at the device or client side.

In the client side (or device side) buffering solution, another approach is employed. During handover in the prior art, the MIP tunnel in the previous radio link is broken first and then regenerated on the new radio link to the HA server. During this period, the packet loss for packets sent over the tunnel can be much greater than at other times. In addition, in the prior art, all data packets transmitted through the prior art tunnel are processed and transmitted with the same priority.

Typically, a constant connection to the Internet is required, and applications running on mobile devices are somewhat robust to packet loss and often incorporate their buffers to accommodate temporary loss or degradation in the connection. During handover, MIH packets, which are somewhat less frequent than application packets, are more important in terms of link stability and reliability guarantee. Thus, embodiments of the second aspect of the present invention prioritize MIH data packets over application data packets.

An application running on a mobile device can handle lost application data packets better than lost MIH data packets, in the absence of MIH data packets, the link may be completely lost, thus allowing applications that rely on persistent connections. May be killed. Thus, it is for the application that the handover is complete and the new link is established quickly so that application data packets are delivered once more immediately.

To prioritize MIH packets, two buffers are created in the mobile device. The first buffer is for MIH data packets and the second buffer is for application data packets. These two buffers operate to take data from the application data buffer only when the MIH data packet buffer is empty. In this way, MIH data packets are given priority over application data packets. This situation is illustrated in the flowchart of FIG. 4.

In step 300, the existing data link layer delivers the packet to be transmitted through the tunnel. In step 310, it is determined whether the transmission packet is a MIH or a handover packet. If the transmission packet is not a handover packet but an application data packet, it is added to the application data packet buffer or bucket in step 340 for transmission in step 350. However, if it is determined in step 310 that the transmission packet is a MIH or handover packet, it is added to the MIH packet buffer or bucket in step 320 for transmission in step 330. Packets from the application data buffer are sent only when the MIH packet buffer is empty.

5 shows how this decision process works. In step 400, a transmission message is received. In step 410, the status of the MIH bucket or buffer is checked. If there are packets to be transmitted in this buffer, the entire contents of the MIH buffer are transmitted in step 420. In step 430, it is checked whether there is a packet to be transmitted to the application data buffer. If there is a packet to be transmitted, one packet is transmitted in step 440 before further checking the MIH buffer in step 450. If it is found that there are more MIH packets to be transmitted, repeat step 420 and continue operation as before. However, if there is no MIH packet in the buffer as a result of the check in step 450, a single application data packet is transmitted and the step 440 is repeated.

In step 410, if there is no MIH packet in the buffer, operation continues from step 430 as described above. In this way, by always giving priority to MIH packets over application data packets, the handover process can give priority to applications running on the mobile device during handover.

In other embodiments, the size of either buffer or both buffers may change dynamically to apply higher or lower priorities to either type of data packet.

Although described above with respect to the buffering of data packets on the client side, it is evident that the same technique can be applied to the server side by giving priority to MIH or handover packets over application data packets. This prioritization can be applied on the server side, client side or both. The greatest benefit comes from applying it to both sides.

Embodiments according to the eighth aspect of the present invention provide a server that operates as described herein.

Embodiments according to the ninth aspect of the present invention provide a tangible computer readable medium for performing the method as described herein.

At least some elements discussed herein may be configured in part or in whole using dedicated special purpose hardware. As used herein, terms such as 'component', 'module' or 'unit' include, but are not limited to, hardware devices such as Field Programmable Gate Arrays (FPGAs) or Application Specific Integrated Circuits (ASICs) that perform specific tasks. It doesn't work.

At least some elements reside on an addressable storage medium and may be configured to execute one or more processors. In other words, the elements may be embodied in the form of a tangible computer readable storage medium having recorded thereon instructions which are in use and executed by a computer or other suitable device. The elements may include, for example, software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, It may include components such as subroutines, segments of program code, drivers, firmware, microcode, databases, data structures, tables, arrays, and variables. The tangible media may take any suitable form, but examples thereof include solid state memory devices (ROM, RAM, EPROM, EEPROM, etc.), optical disks (eg, CDs, DVDs and others), magnetic disks. Magnetic tapes and magneto-optical storage devices.

Example embodiments have been described with reference to example components, modules, and units discussed. Where appropriate, these functional elements may be combined into fewer elements or separated into additional elements. In some cases, the elements are distributed through a plurality of separate computing devices connected to a suitable communication network including all suitable wired or wireless networks.

It should be noted that various different embodiments of the invention described herein may be implemented separately or together, depending on the desired effect. There are no inherent incompatibilities between them, and greater benefits can be gained by creating a system using one or more of the embodiments described above.

Note all papers and documents filed simultaneously with or prior to this specification and subject to public inspection with respect to this application, the contents of which are hereby incorporated by reference.

All features disclosed herein (including the appended claims, abstracts and drawings) and / or all steps of any disclosed method or process, exclude combinations where at least some of those features and / or steps are mutually exclusive. And may be combined in any combination.

Each feature disclosed in this specification (including the appended claims, abstract and drawings) may be replaced with other features for the same, equivalent or similar purpose unless otherwise specified. Thus, unless stated otherwise, each feature disclosed is one example only of a series of equivalent or similar features.

The invention is not limited to the details of the foregoing embodiment (s). The present invention is directed to any novel or any novel combination of the features disclosed herein (including the appended claims, abstract and drawings) or any novel or any novel combination of the steps of the disclosed method or process. Is expanded.

10: MIH Servers 20: Video Streaming Server 10 ': New MIH Server
101: mobile device 110: MIH servers 120: video streaming server
130: MIP HA server 131: tunnel 132: tunnel
201: mobile device 210: MIH servers 220: video streaming server
230: MIP HA server 231: tunnel 232: tunnel

Claims (12)

A method for performing a handover of a mobile device from a first wireless network to a second wireless network, the method comprising:
Sending, by the mobile device, a handover data packet through the tunnel to an information server;
Sending, by the mobile device, a handover data packet to the information server via another path,
The mobile device is connected to a server of a mobile IP (MIP) system and an information server connected to the first and second wireless networks through a tunnel, and the information server is connected to the second wireless network from the first wireless network. And providing handover messages to the mobile device when performing a handover.
The method of claim 1,
And transmitting the handover data packet to the information server through the other path, directly transmitting the handover data packet to the information server using the IP address of the mobile device.
The method of claim 1,
And the handover data packet includes a data packet indicating that the handover is completed.
A mobile device communicating over a first wireless network and a second wireless network,
A server connected to a server of a mobile IP (MIP) system and an information server connected to the first and second wireless networks through a tunnel, and transmitting a handover data packet to the information server through the tunnel and the other path; Includes a mobile device,
And the information server provides handover messages to the mobile device when performing the handover from the first wireless network to the second wireless network.
A method for performing a handover of a mobile device from a first wireless network to a second wireless network, the method comprising:
Determining that the handover is imminent or in progress;
Buffering data packets transmitted from the mobile device,
The mobile device is connected to a server of a mobile IP (MIP) system and an information server connected to the first and second wireless networks through a tunnel, and the information server is connected to the second wireless network from the first wireless network. Providing handover messages to the mobile device when performing a handover of the handover, wherein the handover data packets included in the data packets are transmitted in preference to application data packets.
The method of claim 5,
The handover data packets and the application data packets are buffered separately, and the application data packets are transmitted only when there are no pending handover data packets.
The method of claim 5,
The handover data packets and buffer sizes associated with the application data packets are dynamically changed to adjust the relative priority assigned to the handover data packets and the application data packets. Way.
A mobile device communicating over a first wireless network and a second wireless network,
A tunnel is connected to a server of a mobile IP (MIP) system and an information server connected to the first and second wireless networks, and determines whether a handover is imminent or ongoing, and buffers data packets transmitted from the mobile device. Including the moving device,
The information server provides handover messages to the mobile device when performing a handover from the first wireless network to the second wireless network, wherein the handover data packets included in the data packets are application data packets. A mobile device characterized in that the transmission is prioritized.
A method for performing a handover of a mobile device from a first wireless network to a second wireless network,
Determining that the handover is imminent or in progress;
Transmitting handover data packets from the mobile device at a server and buffering the handover data packets if the handover is imminent or ongoing;
The mobile device is connected to the server of a mobile IP (MIP) system and an information server connected to the first and second wireless networks through a tunnel, and the information server is connected to the second wireless network from the first wireless network. Handover messages to the mobile device when performing a handover to a mobile station.
10. The method of claim 9,
The buffering may include buffering application data packets at the server if the handover is imminent or ongoing.
10. The method of claim 9,
The determining may include determining a handover state at the server by examining data packets to determine the existence of the handover packets.
In the server of MIP (Mobile IP) system,
A server connected to the mobile device through a tunnel and determining that a handover is imminent or in progress, transmitting the handover data packets to the mobile device and buffering the handover data packets;
The mobile device is connected to an information server connected to first and second wireless networks, and the information server performs a handover message to the mobile device when performing the handover from the first wireless network to the second wireless network. Server for providing them.

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