KR20150123386A - CBTC signal system and handover method in the system - Google Patents

Abstract

The present invention relates to a CBTC signaling system, and more particularly, to a CBTC signaling system based on PMIPv6 (Proxy Mobile IPv6) supporting mobility of wireless communication in an IPv6 wireless network and a handover method in the system.
A CBTC signal system according to an embodiment of the present invention includes: an onboard signal device installed in a train and having a wireless communication module therein; A terrestrial signal device installed on a side of a line and wirelessly communicating with the onboard signaling device; A Local Mobility Anchor (LMA) which is connected to the terrestrial signaling device via a LAN and maintains the address and location information of the wireless communication module in the PMIPv6 domain and guarantees connection, allocates a Home Network Prefix (HNP) ; A Mobile Access Gateway (MAG) for tunneling with the LMA to exchange packets, and performing mobility support signaling by taking charge of a connection function and a routing function for a network; An Authentication, Authorization, and Accounting (AAA) server that stores information on the address and address of the LMA, HNP information of the wireless communication module, and service policy, processes and responds to an authentication request for the wireless communication module of the MAG, ; .

Description

[0001] CBTC signal system and handover method in the system [0002]

The present invention relates to a CBTC signaling system, and more particularly, to a CBTC signaling system based on PMIPv6 (Proxy Mobile IPv6) supporting mobility of wireless communication in an IPv6 wireless network and a handover method in the system.

The existing CBTC signaling system is a system using the wireless LAN of the IPv4-based network.

Currently, IPv4-based networks are in a state of IP depletion due to the exponential increase in demand for IP, and the importance of IPv6 has been highlighted.

Existing network equipment supporting IPv4 is also about to be replaced with network equipment supporting IPv6 or supporting both IPv4 and IPv6.

Meanwhile, CBTC (Communication Based Train Control) signal system is a signal system that performs safe operation of trains based on communication between ground and vehicle without using existing track circuit in railway signal system.

In other words, CBTC is a system that can confirm the position of train with high level of precision without orbital circuit if the existing method was a method to train by constituting orbital (track) circuit.

This CBTC signaling system enables data transfer networks between geographically continuous vehicles and line devices, allowing more control and delivery of status information than existing systems.

However, the IEEE 802.11 based wireless LAN used by the existing CBTC system does not include specifications for supporting the mobility of mobile wireless terminals (onboard signal devices mounted on trains).

Therefore, in order to prevent the wireless communication from being disconnected while moving, the wireless communication coverage between the APs should be designed so as to be overlapped as much as possible. As a result, the number of network devices installed on the line increases and the construction cost also becomes large.

Therefore, a technology supporting the mobility of the wireless communication is required, and the system construction cost can be lowered.

The CBTC system, which has been developed and commercialized so far, is based on the IPv4 network and uses a wireless LAN communication method. When the IPv6 network is commercialized, CBTC, which transmits and receives data between trains (on- The system should also use the wireless network based on IPv6 network.

Standards supporting wireless mobile communication in IPv6 networks are under study by the Internet Engineering Task Force (IETF) and this standard is called Mobile IPv6.

However, Mobile IPv6 is an early version of a wireless communication standard that supports mobility in IPv6 networks, and has problems such as long handover latency and packet loss caused thereby.

In order to compensate for the long handover delay time, FMIPv6 (Fast handover for Mobile IPv6) is standard, but there is still an excessive problem of packet order reversal and handover related signaling of the wireless terminal.

There is a hierarchical Mobile IPv6 (HMIPv6) standard for handling handover related signaling at the network layer, but the handover delay to the external domain remains a problem.

In the CBTC system where the signaling device of the moving train and the signal device of the ground must exchange data by stable communication, packet loss and communication disconnection are a big problem and the system itself can not operate properly.

Therefore, the CBTC signaling system based on wireless mobile communication needs to be developed to ensure stable wireless communication in a future IPv6 based network.

Public number 10-2012-0059092 (June 08, 2012) Publication No. 2002-0046291 (June 21, 2002)

The present invention proposes a Proxy Mobile IPv6 (CBIP) signaling system based on PMIPv6 (MIPv6, FMIPv6, HMIPv6), which is a standard for securing the mobility of IPv6 based networks in the IETF. A CBTC signal system for providing continuous wireless communication and minimizing packet loss due to fast handover when a train moves to another network domain, thereby enabling stable system operation and a handover method in the system .

Another object of the present invention is to provide a CBTC signaling system capable of reducing the overlap of communication coverage areas between wireless APs by introducing a standard for supporting mobility in wireless communication, And to provide a handover method in a system.

According to an aspect of the present invention, there is provided a CBTC signal system comprising:

An onboard signaling device installed in a train and having a wireless communication module therein;

A terrestrial signal device installed on a side of a line and wirelessly communicating with the onboard signaling device;

A LMA (Local Area Network), which is connected to the terrestrial signaling device through a LAN and maintains the address and location information of the wireless communication module in the PMIPv6 (Proxy Mobile IPv6) domain and guarantees connection, allocates Home Network Prefix (HNP) (Local Mobility Anchor);

A Mobile Access Gateway (MAG) for tunneling with the LMA to exchange packets, and performing mobility support signaling by taking charge of a connection function and a routing function for a network; And

An Authentication, Authorization, and Accounting (AAA) server that stores information on the address and address of the LMA, HNP information of the wireless communication module, and service policy, processes and responds to an authentication request for the wireless communication module of the MAG, ; .

The MAG is characterized by receiving a trigger for providing attach and detach information of a wireless communication module in a link layer.

The wireless communication module may have one of IPv4 and IPv6, or a dual stack.

The MAG is characterized by identifying the wireless communication module using a MAC (Media Access Control) address of the wireless communication module and using it as an identifier for requesting authentication.

A handover method in a CBTC signaling system according to an embodiment of the present invention includes:

When the wireless communication module of the onboard signaling device moves to the second MAG network area while communicating with the terrestrial signaling device through the LMA in the first MAG network area while the train is operating, the handover method in the CBTC signaling system In this case,

(a) It is confirmed that the wireless communication module is detached from the first MAG, and a detach event is generated. When the detached-proxy binding update (D-PBU) message indicates that the wireless communication module is not in its network area, ;

(b) After receiving the D-PBU message from the LMA, the LMA deletes the item related to the corresponding wireless communication module in its BCE (binding cache entry) and deletes the corresponding wireless communication module through the PBA (Proxy Binding Acknowledgment) Informing the first MAG of the thing;

(c) attempting to establish a connection to the second MAG by including the ID of the wireless communication module in an RS (Router Solicitation) message; And

(d) confirming that the information (ID) of the wireless communication module exists in the second MAG, maintaining the HNP so as to continue to use the HoA (Home Address) that was previously used, prefix to a wireless communication module in a Router Advertisement (RA) message; .

In the step (d), the MAG 2 requests the AAA server to authenticate the wireless communication module, thereby confirming that the information of the wireless communication module exists.

According to the solution of the above-mentioned problem, the IETF proposes a PMIPv6-based CBTC signaling system that complements MIPv6, FMIPv6, and HMIPv6, which are standards for ensuring wireless mobility of IPv6-based networks, Is moved to another network domain, the packet loss can be minimized due to fast handover, and stable system operation can be achieved.

In addition, by introducing a standard supporting mobility in wireless communication, it is possible to reduce overlap of communication coverage area between wireless APs and reduce the cost of purchasing and installing related equipment in system construction.

1 is a block diagram of a PMIPv6-based CBTC signaling system according to an embodiment of the present invention.
FIG. 2 is a diagram schematically illustrating a general IEEE 802.11 based wireless AP construction and a wireless communication overlapping area.
FIG. 3 is a diagram schematically illustrating a wireless AP construction and a wireless communication overlap area when the mobility supporting wireless communication standard according to the present invention is applied.
4 is a diagram for explaining the occurrence of a handover in a general PMIPv6 domain.
5 is a diagram illustrating a train handover procedure in a PMIPv6 environment according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

It is to be noted that the same components of the drawings are denoted by the same reference numerals and symbols as possible even if they are shown in different drawings.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Also, when a part is referred to as "including " an element, it does not exclude other elements unless specifically stated otherwise.

1 is a block diagram of a PMIPv6-based CBTC signaling system according to an embodiment of the present invention.

And includes an onboard signaling device (OATC), a ground signaling device 40, an LMA 10, a MAG 20a and 20b, and an AAA server 30 as shown in FIG.

An Onboard-ATC (OATC) installed on a train has a wireless communication module (WCM) therein and wirelessly communicates with a Wayside-ATC (40).

A Local Mobility Anchor (LMA) 10 is connected to the terrestrial signaling device 40 through a LAN. The gateway 10 has a function of a Local Mobility Anchor (LMA) 10 in a network domain. A Home Network Prefix (HNP) And transmits it to a wireless communication module (WCM) provided in the onboard signaling device OATC.

In addition, the LMA 10 maintains a WCM address and location information of all on-vehicle signaling devices OATC in the domain to ensure connection.

When the entire history section is not covered by one PMIPv6 domain, a packet transmitted from the external domain to the wireless communication module (WCM) of the onboard signaling device (OATC) is received by the LMA 10 and received by the mobile access gateway (MAG) 20b through tunneling.

Conversely, a packet transmitted from the wireless communication module WCM of the onboard signaling device OATC to the outside is tunneled by the MAGs 20a and 20b to the LMA 10, and the LMA 10 transmits the packet to the external domain.

The MAGs 20a and 20b are equipped with the functions of the MAGs 20a and 20b in an access router and perform mobility support signaling in place of the wireless communication module WCM of the onboard signaling device OATC.

That is, the MAGs 20a and 20b perform the location registration process performed by the wireless communication module WCM of the onboard signaling device OATC instead of performing mobility-related signaling, thereby providing efficient and quick mobility, At this time, the wireless communication module (WCM) of the onboard signaling device (OATC) supports either IPv4 or IPv6 or dual function.

Therefore, it is possible to communicate while the IP address is not changed.

The MAGs 20a and 20b are responsible for a connection function and a routing function for the network. When the wireless communication module (WCM) of the onboard signaling device (OATC) accesses the corresponding access router, information on the wireless communication module (WCM) And instead sets the connection with the LMA 10 and transfers the packet received from the LMA 10 to the wireless communication module WCM of the onboard signaling device OATC.

To this end, the MAGs 20a and 20b include a trigger for providing information such as attach and detach of the OATC wireless communication module WCM in a link layer. .

The ID of the wireless communication module (WCM) is always obtainable in the PMIPv6 domain, is identified using the MAC (Media Access Control) address of the wireless communication module (WCM), and is used as an identifier for authentication.

The AAA server 30 that provides authentication, authorization, and accounting manages the address and address setting method of the LMA to be serviced, the HNP of the OATC wireless communication module (WCM) of the train, Information and service policy, and processes and responds to a wireless communication module (WCM) authentication request from the MAGs 20a and 20b.

FIG. 2 is a diagram illustrating a general IEEE 802.11-based wireless AP construction and a wireless communication overlap region, and FIG. 3 is a view schematically illustrating a wireless AP construction and a wireless communication overlap region when applying a mobility supporting wireless communication standard according to the present invention .

In the IEEE 802.11 based wireless LAN shown in FIG. 2, since it is not a scheme for supporting mobility, in order to seamlessly communicate with a terrestrial signal device and a terrestrial signal device of a train, spacings of APs are closely arranged, Should be.

In addition, since there is no handover function supporting mobility, the wireless communication module of the onboard signaling device must reconnect based on the signal strength of the new AP.

On the other hand, since the standard scheme such as PMIPv6 shown in FIG. 3 considers the mobility of the wireless communication module, it is possible to predict a movement to a new AP and perform a fast handover.

Therefore, it is possible to reconnect to a new AP even in a small overlap area, thereby reducing the number of wireless network equipment installed on the side of a line in system construction, thereby reducing cost and system construction time.

4 is a diagram for explaining the occurrence of a handover in a general PMIPv6 domain.

As the train moves from the PMIPv6 domain to another MAG (20a- > 20b), a handover occurs.

That is, when the onboard signaling device OATC of the train moves to the network area of the MAG2 20b while communicating with the terrestrial signaling device 40 via the LMA 10 in the network area of the MAG1 20a, Handover occurs in order to be maintained without interruption.

FIG. 5 is a diagram illustrating a train handover procedure in a PMIPv6 environment according to the present invention. In FIG. 5, an OATC radio communication module (WCM) of a train in a PMIPv6 is connected from a MAG1 20a network area to a MAG2 20b network area And is a timing diagram showing signaling at the time of handover.

While the train is operating, the onboard signaling device OATC moves to the MAG2 20b network area while communicating with the terrestrial signaling device WATC through the LMA 10 in the network area of the MAG1 20a, (S502).

At this time, the MAG1 20a confirms that the onboard signaling device OATC is detached in its own range, generates a detachment event (S504), and transmits the on-vehicle signal (D-PBU) And reports to the LMA 10 that the device OATC is not in its network area (S506).

Here, the PBU message is used by the MAG1 20a to request registration with the onboard signaling device (OATC) wireless communication module (WCM) using the HNP as a message to be sent to the onboard signaling device (OATC) wireless communication module (WCM).

Next, the LMA 10 deletes the item related to the WCM of the OATC wireless communication module of the train in its BCE (binding cache entry) after receiving the D-PBU message, (OATC) wireless communication module WCM is deleted through a Binding Acknowledgment (MOB) Acknowledgment message (S508).

Here, the PBA message is a message sent from the LMA 10 in response to the PBU message sent by the MAG1 20a.

The onboard signaling device (OATC) wireless communication module WCM that has arrived into the range of the MAG2 20b network area attempts to establish connection with the MAG2 20b by including its ID in a RS (Router Solicitation) message (S510).

The MAG2 20b confirms that the information (ID) of the onboard signaling device (OATC) wireless communication module WCM is present and maintains the HNP so that the previously used HoA (Home Address) can be continuously used, (OATC) wireless communication module WCM with the network prefix used by the OATC wireless communication module WCM in a Router Advertisement (RA) message (S512).

In step S512, the MAG2 20b requests the AAA server 30 for authentication of the wireless communication module WCM to confirm that the information (ID) of the wireless communication module WCM exists.

Through this procedure, it is assumed that the onboard signaling device (OATC) wireless communication module (WCM) is connected to the same network and maintains HoA and HNP. It assumes that it is in the same network area without signaling related to the handover and performs communication with the terrestrial signaling device 40. [

According to the PMIPv6-based CBTC signaling system of the present invention, mobility is provided in wireless communication between an onboard signaling device and a terrestrial signaling device in an IPv6 network, thereby enabling stable communication and reducing the number of APs installed on a line, And time can be saved.

Also, when a train moves to another MAG network area in the PMIPv6 domain in the IPv6 network, wireless communication with the terrestrial signaling device can be stably maintained through a handover procedure.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. In addition, it is a matter of course that various modifications and variations are possible without departing from the scope of the technical idea of the present invention by anyone having ordinary skill in the art.

10: LMA 20a, 29b: MAG
30: AAA server 40: ground signal device
OATC: Onboard signaling device WCM: Wireless communication module

Claims (6)

An onboard signaling device installed in a train and having a wireless communication module therein;
A terrestrial signal device installed on a side of a line and wirelessly communicating with the onboard signaling device;
A LMA (Local Area Network), which is connected to the terrestrial signaling device through a LAN and maintains the address and location information of the wireless communication module in the PMIPv6 (Proxy Mobile IPv6) domain and guarantees connection, allocates Home Network Prefix (HNP) (Local Mobility Anchor);
A Mobile Access Gateway (MAG) for tunneling with the LMA to exchange packets, and performing mobility support signaling by taking charge of a connection function and a routing function for a network; And
An Authentication, Authorization, and Accounting (AAA) server that stores information on the address and address of the LMA, HNP information of the wireless communication module, and service policy, processes and responds to an authentication request for the wireless communication module of the MAG, ; ≪ / RTI > The method according to claim 1,
The MAG receives a trigger to provide Attach and Detach information of a wireless communication module in a link layer. The method according to claim 1,
Wherein the wireless communication module has either IPv4 or IPv6, or a dual stack. The method according to claim 1,
Wherein the MAG identifies a wireless communication module using a MAC (Media Access Control) address of the wireless communication module and uses the wireless communication module as an identifier for requesting authentication. When the wireless communication module of the onboard signaling device moves to the second MAG network area while communicating with the terrestrial signaling device through the LMA in the first MAG network area while the train is operating, the handover method in the CBTC signaling system In this case,
(a) It is confirmed that the wireless communication module is detached from the first MAG, and a detach event is generated. When the detached-proxy binding update (D-PBU) message indicates that the wireless communication module is not in its network area, ;
(b) After receiving the D-PBU message from the LMA, the LMA deletes the item related to the corresponding wireless communication module in its BCE (binding cache entry) and deletes the corresponding wireless communication module through the PBA (Proxy Binding Acknowledgment) Informing the first MAG of the thing;
(c) attempting to establish a connection to the second MAG by including the ID of the wireless communication module in an RS (Router Solicitation) message; And
(d) confirming that the information (ID) of the wireless communication module exists in the second MAG, maintaining the HNP so as to continue to use the HoA (Home Address) that was previously used, prefix to the wireless communication module in a Router Advertisement (RA) message; A method for handover in a CBTC signaling system. 6. The method of claim 5,
In the step (d), the MAG 2 requests authentication of the wireless communication module to the AAA server to confirm that the information of the wireless communication module exists.

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