WO2008083928A1

WO2008083928A1 - Method and server for establishing an emergency call connection

Info

Publication number: WO2008083928A1
Application number: PCT/EP2007/064615
Authority: WO
Inventors: Dirk Kröselberg; Murugaraj Shanmugam; Hannes Tschofenig
Original assignee: Siemens Aktiengesellschaft
Priority date: 2007-01-11
Filing date: 2007-12-28
Publication date: 2008-07-17
Also published as: DE102007001690A1; CN101622890A; EP2116094A1; DE102007001690B4

Abstract

The invention relates to a method for establishing an emergency call connection for a mobile device (MS). According to said method, when an emergency call (ECALL) with a predetermined emergency call number is received from the mobile device (MS) via an access network (ASN), an emergency call connection between the mobile device (MS) and an emergency call answering unit (PSAP) is only established if the emergency call (E-CALL) has a predetermined emergency call identifier (EID).

Description

description

Method and server for establishing an emergency call connection

The invention relates to a method for establishing an emergency call connection from a mobile device via an access network, in particular via a wireless access network, to a server

Figure 1 shows the structure of an emergency call connection in a conventional system according to the prior art. A mobile terminal or mobile device (MS: Mobile Station) establishes a wireless connection for the emergency call via an interface R 1 with an access network ASN (ASN: Access Service Network). The access network ASN is a wireless access network, for example a WLAN network or a WiMax network. The WiMax network is an abbreviation for "Worldwide Interoperability for Microware Access", which is based on the IEEE 802.16 standard.A WiMax network also supports emergency services, such as emergency calls to the police, the fire department or an ambulatory Emergency services are increasingly being demanded via such networks since the wireless access network ASN contains, for example, several base stations BS for setting up a radio connection with the mobile terminal MS This access network server ASN-S is connected to a connectivity service network CSN via another interface R3, which may be a wired or wireless interface, while the access network ASN is for network access via an access point is competent, s The network CSN provides the user with the desired services. The network CSN can be connected via other networks, for example the Internet, with an emergency answering device PSAP (Public Safety Answering Point). The emergency answering device is, for example, an emergency answering device of the police, the fire brigade or an out-patient aid service. tes. The Connectivity Service Network CSN contains an emergency call server ECS (Emergency Call Server), which forwards incoming emergency calls to the emergency answering device PSAP. The emergency call server ECS is connected to a mapping server, which uses an integrated database to select the most suitable emergency answering system. This happens, for example, based on information about the location of the mobile terminal MS. For example, by means of the mapping server, the emergency answering device which is located locally close to the mobile terminal MS is selected. For example, if a mobile terminal calls the emergency call of the police, the nearest police station is selected to answer the emergency call.

Figure 2 shows the treatment of an emergency call according to the prior art. In particular, the case is considered where the caller is an anonymous caller who is not an authenticated user of a mobile telephone service. With conventional mobile terminals MS, it is possible for a person, even without approval to a mobile service to make an emergency call, for example, an emergency call to the police or fire department. For example, it is possible for the user of a mobile phone without a SIM card by typing a specific emergency number, for example, "110" or "112" in Germany to send a police emergency call or emergency call for an outpatient service. The user of the mobile terminal MS, which has no authenticated network access, first sends an emergency call request EAR (emergency access request) to the access network ASN, which forwards this emergency call request EAR to the emergency call server ECS in the connectivity service network CSN. As soon as the emergency call server ECS recognizes the emergency call request EAR, it allows the mobile terminal MS to reach the connectivity service network CSN by sending an OK message or a permission message and transmits corresponding configuration data to the access network ASN, which for example has an IP address. a default gateway address or a DNS server address, ie configuration data that the mobile terminal MS needs to reach the emergency call server ECS in the connectivity service network CSN. These configuration data are forwarded by the access network server of the access network ASN to the mobile terminal MS. The transmission of the configuration data to the mobile terminal MS takes place within an unauthenticated network connection (Unauthenticated Network Attachment). After transmission of the configuration data, the user of the mobile terminal MS is able to send an emergency call to the emergency call server ECS. This is the emergency call with a specific

Emergency number, for example, with the police emergency number, sent to the access network ASN, which forwards this emergency call or E-Call (Emergency Call) to the emergency call server ECS. The incoming emergency numbers identify the caller as an emergency call. By way of example, the telephone number "110" is stored as an emergency number in a database of the access network server or access gateway identified as such As soon as the emergency call server has received the emergency call (E-Call), it queries the access location ASN for the location of the mobile terminal MS with an appropriate request

(Location Request). The access network server ASN transmits the emergency server the coordinates of the access point or, for example, the address of the corresponding access point AP. With the help of this information about the whereabouts of the mobile terminal (MS) is selected with the help of a mapping server that emergency answering PSAP, which is the most suitable, for example, which is locally closest to the mobile terminal MS. The mapping server provides the emergency call server ECS with the address for the most suitable emergency answering device

PSAP, so that the emergency server can forward the emergency call (e-call) to the emergency answering system (PSAP). Subsequently, an emergency call connection is established between the emergency answering device PSAP and the mobile terminal MS via the telephone system shown in FIG.

Since the anonymous user of the mobile terminal MS without authentication by sending the emergency call request EAR (Emergency Access Request) has received configuration data, this puts an attacker or malicious user in a position to make other service requests, for example, for other services to the access network ASN. These service requirements are forwarded in the conventional procedure by the access network ASN to the emergency call server ECS. Only the emergency call server ECS recognizes that the service request is an inadmissible request. Accordingly, the emergency call server ECS denies the requested service and ignores the service request of the mobile terminal MS.

However, the procedure illustrated in FIGS. 1, 2 has the disadvantage that the transmission of the configuration data to the mobile terminal MS in response to the emergency call request EAR enables the malicious user of a mobile terminal MS to make a service request via the access network ASN to the emergency call server ECS.

As shown in Figure 3, this allows a malicious user to overload an emergency call server ECS by a variety of incorrect service requests such that it fails. In this case, the service requirements (bogus requests) transmitted by the mobile terminal MS are transferred non-automatically, so that it is not possible to determine from which user the service requests originate. An attacker can thus overload an emergency server by sending a variety of service requests based on the configuration data obtained by the emergency call request, so that it is no longer available for emergency calls from third parties. This poses a considerable security problem. In addition, the interface R3 between the access network ASN and the connectivity service network CSN is burdened by the malicious service requirements of the malicious user, ie the bandwidth and the corresponding resources are wasted. It is therefore the object of the present invention and method to provide a server which protects an emergency call server from attack by a plurality of invalid service request messages of an anonymous mobile terminal.

This object is achieved according to the invention by a method having the features specified in claim 1 and by an access network server having the features specified in claim 17.

The invention provides a method for establishing an emergency call connection for a mobile device, wherein upon receiving an emergency call from a particular emergency number from the mobile device through an access network, an emergency call connection between the mobile device and an emergency answering device is established via the access network only if the emergency call is a predetermined emergency call identification having.

In a possible embodiment of the inventive

Method, the emergency call identification (EID) is formed in response to an IP address within a predetermined IP address space.

In an embodiment of the inventive method, an access network server of the access network ASN checks on receipt of an emergency call, if the emergency call has an identification that is identical to a predetermined emergency call identifier EID, the access network server only forwards the emergency call to an emergency call server ECS, if the Identification match the predetermined emergency call identifier EID.

In one embodiment of the method according to the invention, the access network server of the access network ASN forwards a permissible emergency call, which has the predetermined emergency call identifier EID, to the emergency answering device PSAP via the emergency call server ECS. In one embodiment of the method according to the invention, the access network server of the access network ASN blocks an inadmissible emergency call which does not have the predetermined emergency call identification EID.

In one embodiment of the method according to the invention, the emergency call identifier EID is formed as a function of a predetermined IP client address, an IP server address of the emergency call server ECS and further parameters by the emergency call server ECS.

In one embodiment of the method according to the invention, the further parameters have a time stamp and a validity period.

In one embodiment of the method according to the invention, the predetermined emergency call identification EID can be configured in the access network server of the access network ASN.

In an alternative embodiment of the method according to the invention, the predetermined emergency call identifier EID is formed in the access network server of the access network ASN as a function of a predetermined IP client address, an IP server address IP-ECS of the emergency call server ECS and other parameters.

In one embodiment of the method according to the invention, the mobile device MS receives the emergency call identification EID from the emergency call server ECS in response to an authenticated emergency call request EAR.

In one embodiment of the method according to the invention, upon receipt of a permissible emergency call, which is forwarded by the access network server of the access network ASN to the emergency call server ECS, a suitable emergency answering system is selected based on the emergency call number and closing the emergency call forwarded to the selected emergency answering PSAP.

In one embodiment of the method according to the invention, the access network server of the access network ASN provides the emergency call server ECS with information about the location of the mobile device MS together with the emergency call.

In one embodiment of the method according to the invention, the emergency call server ECS is connected to a mapping server which selects the most suitable emergency answering device PSAP on the basis of the information data about the location of the mobile device MS.

In one embodiment of the inventive method, the access network is formed by a wireless access network.

In one embodiment of the method according to the invention, the wireless access network is formed by a WLAN network.

In one embodiment of the inventive method, the wireless access network is formed by a WiMax network.

The invention further provides an access network server for setting up an emergency call connection for a mobile device MS, wherein the access network server, upon receiving an emergency call with a predetermined emergency number from the mobile device MS establishes an emergency call connection between the mobile device MS and an emergency answering device PSAP if the emergency call reaches a predetermined one Emergency Identification EID.

In the following, preferred embodiments of the method according to the invention and the server according to the invention for setting up an emergency call connection for a mobile device will be described in more detail with reference to the enclosed figures to explain features essential to the invention. Show it :

Figure 1 shows a telephone system for establishing an emergency call connection according to the prior art;

Figure 2 is a signal diagram showing the structure of an emergency call connection according to the prior art;

FIG. 3 shows a diagram for illustrating a possible attack in a conventional telephone system according to the prior art;

FIG. 4 shows a signal diagram to illustrate the method according to the invention for setting up an emergency call connection;

FIG. 5 shows a diagram for illustrating the defense against an attack in a telephone system which uses the method according to the invention for setting up an emergency call connection.

As can be seen from FIG. 4, the user of a mobile terminal MS initially receives configuration data in response to an emergency call request EAR (Emergency Access Request), which makes an emergency call possible. For this purpose, an emergency call request EAR is first sent to the access network ASN by the mobile terminal MS. The emergency call request EAR is sent, for example, via a wireless interface from the mobile terminal MS to a base station BS of a wireless access network ASN and from there to an access network server ASN-S or to a gateway of the access network ASN. The access network server forwards the emergency call request EAR via a further interface to an emergency call server ECS within a connectivity service network CSN. As soon as the emergency call server ECS recognizes the emergency call request, it transmits the necessary configuration data for setting up an emergency call connection via the access network ASN to the mobile terminal MS. It contains the corresponding confirmation message or OK message a predetermined NotrufIdentifizierung EID.

The emergency call identifier EID is, for example, a specific unique IP address, a specific IP address range, source and / or destination MAC addresses, or even source and / or port numbers. In an alternative embodiment, the emergency call identifier EID is generated as a function of an IP address within a predetermined IP address space in accordance with a predetermined function. In another embodiment, the emergency call identification is formed as a function of a plurality of IP addresses, namely a predetermined IP client address, an IP server address of the emergency call server ECS and other parameters. These further parameters include, for example, a timestamp and a validity period of the emergency call identification EID.

This emergency call identifier EID is transmitted by the emergency call server ECS together with the confirmation message, which contains the configuration data, for example as SFID (Service Flow Identifier) to the mobile terminal MS. The access network server of the access network ASN also has the emergency call identification EID. In this case, this emergency call identifier EID is configured in the access network in one embodiment. In an alternative embodiment, the access network server of the access network ASN receives the emergency call identifier EID from the emergency call server ECS by means of a message.

Once the mobile terminal MS has received configuration data including the emergency call identification EID from the access network server of the access network ASN, it is now able to make the actual emergency call. For this purpose, the user of the mobile terminal MS selects a predetermined emergency number and transmits the emergency call (ECal) including the configuration data with the received emergency call identification EID to the access network server of the access network ASN. Is the emergency call or emergency call (ECal) an additional call A casual emergency call containing the correct emergency call identification EID, the access network server of the access network ASN forwards the emergency call received from the mobile terminal MS. If the emergency call is an inadmissible emergency call that does not have the correct emergency call identification EID, the access network server of the access network ASN blocks the received emergency call. Upon receipt of the emergency call, the access network server of the access network ASN checks whether the emergency call contains an emergency call identification and whether this emergency call identification is identical or not to the prescribed emergency call identification EID. The emergency call is forwarded by the access network server to the emergency call server ECS only if the emergency call identification contained in the emergency call matches the predetermined emergency call identifier EID. If the emergency call identification contained in the emergency call is not identical to the predetermined emergency call identification, the access network server refuses to forward the emergency call or ignores the emergency call.

The emergency call server ECS then queries the access network server for the spatial location of the mobile terminal MS. The access network server provides, for example, the coordinates of the access point AP (access point) of the mobile terminal MS or a mailing address of such an access point AP. The emergency call server ECS thus receives, as shown in FIG. 4, information on the location of the mobile device MS on request. In an alternative embodiment, after examining the emergency call identifier EID, this information data is sent directly to the emergency call server ECS together with the emergency call (e-call) without the latter having to request the information data from the access network ASN.

As soon as the emergency call server ECS has received the permissible emergency call together with the information about the location of the mobile terminal MS, it performs a selection for a suitable emergency answering device PSAP with the aid of a mapping server. The mapping server is connected to the emergency call server ECS and contains a database which contains the network addresses of a plurality of emergency answering devices. On the basis of the whereabouts of the mobile terminal MS, for example, the emergency call answering device PSAP located next to it is selected and made available to the emergency call server ECS. The mapping server thus transmits the PSAP address of the suitable emergency answering device as a function of the location of the mobile terminal MS. As soon as the emergency call server ECS has received the PSAP address from the mapping server, it forwards the permissible emergency call E-Call to the selected emergency answering device PSAP. Subsequently, an emergency call connection between the emergency answering device PSAP and the mobile terminal MS is established. As can be seen from FIG. 4, in the case of the method according to the invention, it is thus still possible to use a mobile terminal

MS an emergency call to an emergency answering PSAP, such as a police emergency call or a fire service emergency call to build.

In the method according to the invention, however, it is prevented that a malicious user can send service requests for other services to the emergency call server ECS by means of the configuration data obtained from the emergency call server ECS in response to his emergency call request EAR. If the mobile terminal MS sends a service request with the received configuration data, including the emergency identification EID, to the access network server of the access network ASN, the access network server recognizes, on the basis of the identification contained therein, that it is an emergency identification EID that merely establishes the user of the mobile terminal MS authorized an emergency call. Other services can not be used by the user of the mobile terminal MS with the EID emergency identification. Therefore, in the method according to the invention, the access network server of the access network ASN refuses the service request for another service if it contains an emergency call identification EID. Only the service request for an emergency call is forwarded to the emergency call server ECS. As can be seen by comparing FIGS. 2, 4, the access network server of the access network ASN already blocks an attacker's service request, which includes an emergency call identification EID, if the service request is a Bogus request requesting a different service, in which it is not about setting up an emergency call. Thus, an attacker in the inventive method is prevented from sending a plurality of invalid service request messages directly to the emergency call server ECS to overload it if necessary. In addition, the interface between the access network server of the access network ASN and the emergency call server ECS is not burdened by such inadmissible service requirements or these resources are spared.

In the method according to the invention, the access networks ASN can be any access networks, for example wireless access networks such as WLAN or WiMax.

As can be seen from FIG. 5, an attack by a malicious user on the emergency call server ECS or the misuse of the emergency call service for non-emergency services is prevented. The mobile terminal MS receives an acknowledgment message on an emergency call request EAR (emergency access request) from the emergency call server ECS together with a predetermined emergency call identifier EID as configuration data. Sends the mobile terminal MS a variety of so-called Bogus service requests (BSR) to the access network ASN, the other

Services, eg B. require the establishment of a normal telephone connection to a friend of the user, recognizes the access network server of the access network ASN based on the contained emergency call identification EID that it is an unacceptable service request and denied the corresponding service. Only one emergency call service request with a correct emergency call identification is sent to the emergency call server ECS of the connectivity service network. works CSN forwarded. A shield against illegal BSR (Bogus service request) thus takes place in the inventive method already in the access network ASN, so that a forwarding of such inadmissible service requirements via the interface between the access network ASN and the Connectivity Service Network CSN is prevented.

Claims

claims

A method for setting up an emergency call connection for a mobile device (MS), wherein upon receiving an emergency call (ECALL) with a predetermined emergency number from the mobile device (MS) through an access network (ASN) an emergency call connection between the mobile device (MS) and an emergency answering device ( PSAP) is established via the access network (ASN) only if the emergency call (E-CALL) has a predetermined emergency call identification (EID).

The method of claim 1, wherein the emergency call identification (EID) is formed in response to a source IP address within a predetermined IP address space, a particular destination IP address, specific port numbers, source and destination MAC addresses ,

3. The method of claim 1, wherein an access network server of the access network (ASN), upon receiving an emergency call, checks whether an identification contained therein is identical to a predetermined emergency identification (EID) and only forwards the emergency call to an emergency call server (ECS). if the identification included in the emergency call matches the predetermined emergency identification (EID).

4. The method of claim 3, wherein the access network server of the access network (ASN) an approved emergency call having the predetermined NotrufIdentifizierung (EID), via the emergency call server (ECS) to the emergency answering device (PSAP) forwards.

5. The method of claim 3, wherein the access network server of the access network (ASN) blocks an unauthorized emergency call that does not have the predetermined emergency call identification (EID).

6. The method according to claim 1, wherein the emergency call identifier (EID) is formed by the emergency call server (ECS) depending on a given IP client address, an IP server address of the emergency call server (ECS) and other parameters.

The method of claim 6, wherein the further parameters include a time stamp and a validity period.

The method of claim 3, wherein the predetermined emergency call identification (EID) is configurable in the access network server of the access network (ASN).

9. The method according to claim 3, wherein the predetermined emergency call identification (EID) in the access network server of the access network (ASN) in dependence on a predetermined IP client address, an IP server address (IP-ECS) of the emergency call server (ECS) and further parameters is formed.

10. The method of claim 1, wherein the mobile device (MS) receives the emergency call identification (EID) from the emergency call server (ECS) upon an unauthenticated emergency call request (EAR).

11. The method of claim 3, wherein upon receipt of a permissible emergency call, which is forwarded by the access network server of the access network (ASN) to the emergency call server (ECS), based on the emergency number ne ne suitable emergency answering device selected and then the emergency call to the selected emergency answering device is forwarded.

The method of claim 11, wherein the access network server of the access network (ASN) provides the emergency call server (ECS) with information about the location of the mobile device (MS) along with the emergency call.

13. The method according to claim 12, wherein the emergency call server (ECS) is connected to a mapping server which selects the appropriate emergency answering device (PSAP) on the basis of the information data about the location of the mobile device (MS).

14. The method of claim 1, wherein the access network is formed by a wireless access network.

The method of claim 14, wherein the wireless access network is formed by a WLAN network.

The method of claim 14, wherein the wireless access network is formed by a WiMax network.

17. An access network server for establishing an emergency call connection for a mobile device (MS), the access network server establishing an emergency call connection between the mobile device (MS) and an emergency answering device (PSAP) upon receiving an emergency call with a predetermined emergency number from the mobile device (MS) when the emergency call has a predetermined emergency call identification (EID).