DE102006020835A1 - Device and method for supporting the feature "hand-off call" in FMC networks - Google Patents

Abstract

In the prior art, there is the problem that the switching of a connection section of a connection (hand off) existing between two subscribers of an FMC network (Fixed Mobile Conversion) to another transmission protocol is not supported by the network. The invention solves this problem in that a switchover request from a dual mode terminal (DMH) causes the network to switch the last connection section to this terminal to a different transmission protocol, leaving the remaining connection section to the other subscriber untouched.

Description

contraption and methods of assistance of the feature "Hand Off Call "in FMC Networks.

newer Communication architectures see the separation switching-oriented Networks in connection service-related units and transport the payload (Bearer Control). This results in a Decomposition / separation of connection setup and medium or bearer setup. The transfer The user information (through the user channel) can be via different high bit rate transport technologies such as e.g. ATM, IP or frame Relay be made.

With One such separation is the telecommunications services currently operated in narrowband networks also to realize in broadband networks. This will be the participants either directly (e.g. DSS1 protocol) or via as a Media Gateway Controller (MGC) trained exchanges (eg over the ISUP protocol). The payload itself be over of Media Gateways (MG) into the respective transport technology used transformed.

The Control of the media gateways are assigned by respective media Gateway Controllers (MGC) performed. To control the media Gateways use the Media Gateway Controller normalized protocols, such as As the MGCP protocol or the H.248 protocol. To communication the media gateway controllers use one another through the ITU standardized BICC (Bearer Independent Call Control) protocol, which is formed from a plurality of standardized protocols is and thus includes a protocol family.

One adequate to the BICC protocol Protocol is with the IETF Standardisierungsgremium with the SIP protocol (RFC3261) or the addition SIP-T (RFC3204) / SIP-I. With the latter can ISUP messages - im Contrary to the SIP protocol - transferred become. The transfer ISUP messages are generally done by tunneling, i. H. through transparent passing through.

Of the Connection is established between 2 or more SIP subscribers using SIP protocol elements. Here are under other SDP (Session Description Protocol) data exchanged. SDP data are (bearer) endpoint-related data that provides information about the terminals or codecs, IP port, IP address, etc. included. Should a connection between a SIP subscriber and an H.323 or TDM / ISDN subscriber must be created these SIP protocol elements in the participating media gateway controllers implemented accordingly in H.323, TDM or ISDN protocol elements become.

The first fundamental considerations have led to the Draft Recommendation Q.1912.5 "Interworking SIP and BICC / ISUP" within the ITU-T, with the first considerations regarding the Supplementary Services known from the ISDN world being made, as well as the standardization body 3GPP for mobile Participants where SIP-based services are specified (TS 24.229) In particular, an architecture is specified and standardized in the IMS (IP multimedia subsystem) as described in 2 is shown.

Basically in the ITU-T Q.1912.5 recommendation the ratios are specified as they are arise between SIP and PSTN participants. There will be no Difference between wired and mobile subscribers made. For However, FMC networks (fixed mobile conversion, ie mixed mobile fixed networks) Non-mobile participants are also used. It will in such FMC networks with different units such as clients and interworking units (MGCF, MGC etc.) for an interworking of all networked ones Units come.

This This is especially the case with the "Hand Off" feature for example, between the SIP protocol / WLAN protocol and the GSM protocol are used. "Hand Off" means that two participants - one SIP / WLAN participants and any participant - with each other over one SIP protocol communicate, and the SIP / WLAN participants during the call decides to use his communication over SIP / WLAN over the GSM protocol. The terminals have to be designed accordingly, d. H. they both have to Support protocols (DMH, dual mode phones, GSM / SIP). The connection will be during the Switching process not dismantled. "Hand Off" Call requires signaling to one Central facility in the network (MCF, Mobility Control Function), the Switching from the IMS system from SIP / WLAN to the GSM terminal or vice versa for the participating terminal DMH controls.

Of the Invention is based on the object to show a way how realized the feature "Hand Off" in FMC networks can be.

The Invention is based on the in the preamble of claim 1 features specified by the claimed in the characterizing part Characteristics solved.

Of the Advantage of the invention is the fact that with the proposed solution a purely by signaling controlled switching ("hand off") between two transmission protocols is controlled flexibly. The connection (call) remains during the Umschaltevorganges between the two terminals exist, a down or Building the entire connection is not necessary.

The Control takes place by providing a new identifier in the transmission protocol. As signaling transmission protocols are the SIP, ISUP, ISDN, or GSM protocol into consideration. In order to stands the terminals this new identifier is available and can then be used in the actual hand-off call (such as the IAM, SETUP and INVITE) returns to the parent Control device or application server are returned. So that can the latter this interface or the section between the control device and the subscriber identified by the identifier find again and the changeover from the old transmission section towards new transmission section z. B. according to RFC3725 (3pcc) accomplish. Furthermore, the mapping is this new identifier or the transfer this new identifier is provided from one to the other protocols.

The The invention will be described below with reference to a figuratively illustrated embodiment explained in more detail.

It demonstrate:

1 the basic relationships between PSTN and / or mobile subscribers, between which an internet network is arranged,

2 the IM subsystem according to standard TS24.229,

3 the concrete design of an FMC network,

1 shows the basic relationships between PSTN and / or mobile subscribers, between which an Internet network is arranged. Here, by way of example, two PSTN networks are disclosed, in each of which a plurality of PSTN subscribers are connected in a known manner. These are brought to local exchanges LE, which in turn are connected to transit exchanges TX.

In the transit exchanges TX, the separation between signaling information and payload information is now performed. The signaling information is supplied by the transit exchange TX directly via an ISUP protocol to a respectively assigned media gateway controller MGC (MGC A or MGC B). The user information who the transmitted to a (input side) Media Gateway MG (MG A or MG B), which acts as an interface between the TDM network and an ATM or IP transmission network and are transmitted packet-oriented over the relevant transmission network. The media gateway MG A is controlled by the media gateway controller MGC A as well as the media gateway MG B by the media gateway controller MGC B. In the case of transmission of the payload from the media gateway MG A to the media gateway MG B, the payload is again under Control of the media gateway MG B assigned Media Gateway Controller MGC B are converted into a TDM data stream and fed to the candidate PSTN participants. The data transmitted between the media gateway controller MGC and the respectively assigned media gateway are supported by a standardized protocol. This can be, for example, the MGCP or the H.248 protocol. Between the two media gateway controllers MGC A, MGC B, the SIP protocol is preferably used according to the present embodiment. Finally, a subsystem IMS with facilities P-CSCF, PDF is introduced at the media gateway controller MGC B, via the mobile subscriber with z. B. the PSTN participants are connectable. Basically, it is in the 1 already shown configuration around an FMC network in its simplest form.

2 shows the definition and tasks of the IMS system according to 3GPP TS 23.002 V6.5.0 (2004-06) standard. Here a BGCF (Breakout gateway control function) functionality is described. Furthermore, facilities CSCF, P-CSCF and other facilities are shown, their interaction also in above standard is explained. For example, the BGCF function (breakout gateway control function) selects the network (domain, eg PSTN) into which the call originating from a SIP terminal UE is to be routed. If the BGCF function determines that the destination is on its own network, ie the network in which the BGCF function is located, the BGCF function selects MGCF functionality responsible for interworking with the PSTN network. If the destination is in another network, the BGCF function forwards the signaling to the other network. Finally, can 2 the device P-CSCF which acts as the control of the interface Gq. Here is a function PDF (Policy Decision Function) filed, which specifies the rules in the network.

3 shows an FMC network with a plurality of structures. Accordingly, a plurality of meshed networks are removable. These include mobile (GRPS, UMTS) and fixed (xDSL, LAN) subscriber access networks as well as wireless subscriber access networks (WLAN) and the conventional GSM networks and PSTN / ISDN networks. As a transition point each network subsystems IMS or domains are arranged. Further is 3 a device MCF, which controls the conditions in the network for the feature "Hand Off".

It It is now assumed that a participant A with a participant For example, about the Wants to communicate SIP protocol. It must already be known when connecting that participants A wants a connection to a terminal DMH. All construction wishes of Calls to or from terminals DMH will be over the device MCF led. This has due to the administration knowledge about that for example, the terminal of the subscriber B is designed as a dual-mode terminal DMH and thus supports the SIP / WLAN protocol as well as the GSM protocol. There the terminal from participant B according to present embodiment as a mobile device is to be trained, it is with the device MCF over the Wi-Fi (or DSL) protocol connected. Both terminals communicate directly or indirectly via the SIP protocol with each other, which means that the SIP signaling be passed from the device MCF to the terminal of subscriber B. The SIP Bearer (RTP) is over WLAN / DSL if necessary over the media proxy to the participant B introduced (Gi / Mb). This means, that this is a SIP over WLAN / DSL subscriber acts.

According to the invention will now proposed in the device MCF when establishing a new connection To assign identifier ID. This is in the course of the connection setup handed over to participant B. The device MCF present in the connection path thus additionally generates the SIP basic information elements this new identifier ID, the in the following in the INVITE message for calls in the direction of the terminal of Transfer participant B becomes. The identifier ID is also in the INVITE message following answer (18x, 200 OK) from the institution MCF to participants A guided, if subscriber A is a terminal DMH is. After successful completion of the connection establishment is the connection and both participants communicate with each other Help of the SIP protocol.

Attendees B would like Now in the following the communication with participant A over the Stop SIP / WLAN protocol and with a new protocol such as continue the GSM protocol. This may be necessary if subscriber B uses the SIP data WLAN Bearer has received and he now wants to leave the wireless area. For this is provided that participants B arranged one at his terminal Button pressed. The corresponding information is provided by sending the identifier ID displayed / signaled in the course of a subscriber B outgoing GSM connection request again transmitted to the device MCF becomes. This is possible, because the terminal DMH yes over at the same time both possibilities (GSM and SIP / WLAN), and the over the protocol identifier ID received within the terminal for disposal and internally passed to the other protocol.

The Setup MCF receives thus an INVITE message in which the identifier ID is inserted. In particular, it is hereby specified which part / section of the entire connection path now be driven with the GSM protocol should, so here by the GSM transmission protocol should be replaced. According to the present embodiment it is assumed that only the connecting section between the device MCF and subscriber B with the GSM protocol is driven. Between participant A and the device MCF continue to transmit the information using the SIP protocol (because, for example, the terminal supported by subscriber A only SIP). Naturally is it undecided that both participants involved with terminals DMH equipped could be, then with both DMH's their own section between themselves and the institution MCF designated identifiers ID1 and ID2 received.

In the course of changing the transmission protocol, the physical connection paths over which the payload information is transmitted must also be changed. The corresponding tax operations will be also performed by the device MCF (eg with the aid of RFC3725).

When Criterion for Switching is the operation here one on the terminal arranged button has been addressed. As another criterion would come for example the radio strength or similar Parameters in question.

Of the Identifier ID is generated by the device MCF. In the present Case will be the existing old section passing through the log WLAN represents is replaced by a new section represented by the GSM protocol is replaced. in principle takes place after pressing the button on the terminal DMH of the subscriber B establishes a connection to the device MCF. If this connection is successful (where appropriate then in the meantime two connections (three connecting sections) exist) only then the existing WLAN connection is released.

For realization, a new SIP header must first be defined in the SIP protocol. This has the following form (Table 1):
MCFCall-legIdentifier = ("MCFCall-legIdentifier") HCOLON: legident
Legend = 1 * DIGIT

Tab. 1

in this connection is denoted by MCFCall-legIdentifier the header name, and with 1 * DIGIT the contents of the header. This SIP header is now in the INVITE message and the following acknowledgment messages 200 OK, transported 18x.

In In the present case, it was assumed that the second connecting section is characterized by the SIP / WLAN protocol. The SIP signaling messages are thus accepted by the device MCF from the terminal of the subscriber A, and to the terminal of the participant B transferred. The WLAN protocol acts as a carrier of the SIP signaling messages. Special precautions are not to be taken with the WLAN protocol.

The terminal of participant B should according to present embodiment after pressing the button over the GSM protocol to be connected to the device MCF and with can communicate with the A-TLN. For this purpose, a new identifier is also present in the ISUP and GSM protocol ID to provide.

signal:

First, a new ISUP parameter (MCF call leg identifier parameter) is defined according to ITU-T: Q763 recommendation (Table 2):

signal:

Filler

• In case of an odd number of address signals, the filler code 0000 is inserted after the last address signal.

Tab. 2

in this connection The Q.763 recommendation allows the national use of values between 1111 1111 and 1100 0001 for the value of the parameter.

In the device MGCF (see 2 ), the SIP protocol is now converted into the ISUP protocol. The identifier of the SIP protocol is transferred to the identifier of the ISUP protocol. The identifier of the ISUP protocol should also be provided in the protocol elements IAM, ACM, ANM, CON, CPG.

The conversion (mapping) between SIP and ISUP protocol and vice versa can be done as an example as follows:
The parameter "MCFCall-legIdentifier: 1234" according to the SIP protocol becomes:

One ISUP parameter defined in this way is then still available via the air interface of the UE mobile radio interface (GSM protocol). This is done according to the recommendation TS 04.08 3GPP TS 04.08 V5.20.0 (2003-07) in a known manner. Of the Identifier ID is according to Definition in the ISUP protocol (Q.763) easily reused and taken over. The identifier of the GSM protocol should now also be included in the protocol elements SETUP, Alerting, connect, progress.

The Implementation / transfer (mapping) between ISUP and UE Interface and vice versa, according to TS 04.08 3GPP TS 04.08 V5.20.0 (2003-07) recommendation. This is the parameter simply in the existing messages on TCAP and passed on in reverse.

After all can still be the case that on the section between the Setup MCF and the terminal of the subscriber B an ISDN protocol (Q.931) application finds. Also here takes place - how in the case of the GSM protocol - one easy reuse and takeover the parameter of the ISUP protocol (Q.763). The identifier of the ISDN Protocol should now also be included in the protocol elements SETUP, Alerting, connect, call proceeeding.

The Implementation (mapping) between ISDN and ISUP and vice versa can by simply handing over the parameters in the existing messages respectively.

Claims (7)

Method for supporting the feature "hand-off" in communication networks, wherein a connection is formed between a first (A) and a second subscriber (B) of the communication network, which is routed via a central device (MCF) and between the first subscriber ( A) and the central device (MCF) a first transmission protocol (SIP) and between the latter and the second subscriber (B) optionally a second transmission protocol (SIP, GSM) is used, characterized in that an identifier (ID) in each of the Transmission protocols (SIP, GSM) is provided that from one of the terminals (A, B) a switching request in the transmission protocol (GSM) of the central device (MCF) is communicated using the identifier (ID), from which then a further connection with the new transmission protocol (GSM) between the central device (MCF) and the initiating terminal (A, B) is controlled that Si gnalisierungdaten and bearer data of the Umschaltewunsch not initiating terminal (A, B) are taken over in the further connection, and that between the central device (MCF) and the initiating terminal (A, B) existing connection with the old transmission protocol (SIP) degraded becomes. Method according to claim 1, characterized in that the switchover request is supported by one of several transfer protocols terminal (DMH) is initiated. Device according to claim 1, 2, characterized in that that the Umschaltewunsch arranged in accordance with one of the terminal Button or due to the field strength / radio quality made becomes. Method according to one of the preceding claims, characterized characterized in that in the course of the change of the transmission protocol from the central facility (MCF) to the switch-initiating initiator terminal (DMH) if necessary, the physical connection paths are changed. Method according to one of the preceding claims, characterized in that the communication networks are designed as networks (FMC) are made up of at least one fixed network share and at least one share a mobile network are formed. Method according to one of the preceding claims, characterized characterized in that the first transmission protocol as SIP transmission protocol is trained. Method according to one of the preceding claims, characterized characterized in that the second transmission protocol as a GSM transmission protocol is trained.