WO2007128618A1

WO2007128618A1 - Device and method for support of the performance feature “hand off call” in fmc networks

Info

Publication number: WO2007128618A1
Application number: PCT/EP2007/052686
Authority: WO
Inventors: Klaus Hoffmann
Original assignee: Nokia Siemens Networks Gmbh & Co. Kg
Priority date: 2006-05-04
Filing date: 2007-03-21
Publication date: 2007-11-15
Also published as: DE102006020835A1

Abstract

According to prior art, the problem arises that the switching of a connection section of a connection (Hand Off) between two participants of a FMC network (Fixed Mobile Conversion) to another transmission protocol is not supported by the network. The invention aims to solve said problem by means of the switching request emanating from the Dual Mode terminal (DMH) causing the network to switch the previous connection section of this terminal to another transmission protocol and, in doing so, leaving the residual connection section to the other participant untouched.

Description

description

Device and method for supporting the feature "Hand Off Call" in FMC networks.

Newer communication architectures provide for the separation of switching networks in connection service-related units and the transport of the user information (Bearer Control). This results in a decomposition / separation of connection structure and medium or Beareraufbau. The transmission of the payload information (throughput of the payload channel) can take place via different high bit rate transport technologies, such as e.g. ATM, IP or Frame Relay.

With such a separation, the currently conducted in narrow-band networks telecommunication services are also to be implemented in broadband networks. In this case, the subscribers are connected either directly (for example via a DSS1 protocol) or via exchanges designed as media gateway controllers (MGC) (for example via the ISUP protocol). The payload itself is converted by media gateways (MG) into the respective transport technology used.

The control of the media gateways are performed by respectively assigned media gateway controllers (MGC). To control the media gateways, the media gateway controllers use standardized protocols, such as: As the MGCP protocol or the H.248 protocol. To communicate with each other, the media gateway controllers use a standardized by the ITU BICC (Bearer Independent Call Control) protocol, which is formed of a plurality of standardized protocols and thus includes a protocol family.

An adequate protocol to the BICC protocol was developed by the IETF standardization body with the SIP protocol (RFC3261) or the addition SIP-T (RFC3204) / SIP-I. With the latter, ISUP messages - in contrast to the SIP protocol - be transmitted. The transmission of the ISUP messages is generally carried out by tunneling, ie by transparent transmission.

The connection between two or more SIP subscribers takes place with the aid of SIP protocol elements. Among other things, SDP (Session Description Protocol) data is exchanged. SDP data is (bearer) endpoint-related data that contains information about the end devices or codecs, IP port, IP address, and so on. If a connection is to be established between a SIP subscriber and a H.323 or TDM / ISDN subscriber, these SIP protocol elements must be converted into H.323, TDM or ISDN protocol elements in the participating media gateway controllers accordingly ,

The first fundamental considerations have led to the Draft Recommendation Q.1912.5 "Interworking SIP and BICC / ISUP" within the ITU-T, where the first considerations regarding the Supplementary Services known from the ISDN world have been 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 shown in FIG.

In principle, the ITU-T Q.1912.5 recommendation specifies the relationships between SIP and PSTN subscribers. There is no difference between line-bound and mobile subscribers. However, FMC networks (fixed mobile conversion, ie mixed mobile fixed networks) also use non-mobile subscribers. Thus, in such FMC networks with different units, such as clients and network tiers (MGCF, MGC, etc.), interworking of all the units networked together will occur. This is particularly the case with the feature "hand off." This feature can be used, for example, between the SIP protocol / WLAN protocol and the GSM protocol. "Hand off" means that two subscribers - ie a SIP / WLAN subscriber and a Any participant - communicate with each other over a SIP protocol, and the SIP / WLAN participants during the conversation decides to conduct his communication instead of SIP / WLAN via the GSM protocol. The end devices must be designed accordingly, ie they must support both protocols (DMH, dual mode mobile phones, GSM / SIP). The connection is not cleared during the switchover process. "Hand Off" Calling causes the signaling to a central device in the network (MCF, Mobility Control Function), which controls the switching from the IMS system from SIP / WLAN to GSM terminal or vice versa for the participating terminal DMH.

The object of the invention is to indicate a way in which the "hand-off" feature can be implemented in FMC networks.

The invention is achieved on the basis of the features specified in the preamble of patent claim 1 by the features claimed in the characterizing part.

The advantage of the invention can be seen in the fact that the proposed solution flexibly controls a handoff between two transmission protocols which is controlled purely by signaling The connection (Call) remains during the switching process between the two terminals It is not necessary to dismantle or set up the entire connection.

The control takes place by providing a new identifier in the transmission protocol. As signaling transmission protocols, the SIP, ISUP, ISDN, or GSM protocol can be considered. This is the final devices to this new identifier to And can then be sent back to the parent controller or application server at the actual hand off call (such as the IAM, SETUP, and INVITE). Thus, the latter can unambiguously retrieve this interface or the section between the control device and the subscriber, which is designated by the identifier, and redirect from the old transmission section to the new transmission section, for example. B. according to RFC3725 (3pcc) accomplish. Furthermore, the mapping of this new identifier or the transfer of this new identifier from one to the other protocols is provided.

The invention will be explained in more detail below with reference to an exemplary embodiment shown in FIG.

Show it:

Figure 1 shows the basic conditions between PSTN and / or mobile participants, between which a

Internet network is arranged

FIG. 2 shows the IM subsystem according to standard TS24.229, FIG. 3 shows the concrete design of an FMC network,

Fig. 1 shows the basic conditions 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 payload information is the to a (input side) arranged Media Gateway MG

(MG A or MG B) transmitted as an interface between

TDM network and an ATM or IP transmission network and are transmitted via the relevant transmission network packet-oriented. The Media Gateway MG A is powered by the Media

Gateway controller MGC A controlled as well as the media

Gateway MG B from 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 converted under control of the media gateway MG B associated Media Gateway Controller MGC B in a TDM data stream and the candidate PSTN participants are supplied. 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 in accordance with the present exemplary 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, the configuration shown in FIG. 1 is already an FMC network in its simplest form.

Fig. 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, devices CSCF, P-CSCF and other devices are shown whose interaction is also explained in the above standard. 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 target 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 If the destination is in another network, the BGCF function forwards the signaling to the other network. Finally, FIG. 2 shows the device P-CSCF, which functions as the control of the interface Gq. Here is a function PDF (Policy Decision Function) filed, which specifies the rules in the network.

Fig. 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 conventional GSM networks and PSTN / ISDN networks. As a transition point each network subsystems IMS or domains are arranged. Furthermore, FIG. 3 shows a device MCF which controls the conditions in the network for the feature "hand-off".

It is now assumed that a subscriber A would like to communicate with a subscriber B, for example via the SIP protocol. In this case, it must already be known when establishing the connection that subscriber A wishes a connection to a terminal DMH. All setup requests of calls to or from terminals DMH are routed via the facility MCF. This has due to the administration knowledgeable 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. Since the terminal of subscriber B should be designed according to the present exemplary embodiment as a mobile terminal, it is connected to the device MCF via the WLAN (or DSL) protocol. Both terminals communicate with each other directly or indirectly via the SIP protocol, which means that the SIP signaling from the device MCF to the terminal of subscriber B are guided. The SIP bearer (RTP) is introduced via WLAN / DSL if necessary via the media proxy to the subscriber B (Gi / Mb). This means that this is a SIP over WLAN / DSL participants. According to the invention, it is now proposed to assign a new identifier ID in the device MCF when establishing a connection. This will be handed over to subscriber B in the course of establishing the connection. The device MCF located in the connection path thus generates, in addition to the SIP basic information elements, this new identifier ID, which is subsequently transmitted in the INVITE message for calls in the direction of the subscriber B terminal. The identifier ID is also routed in the response following the INVITE message (18x, 200 OK) from the device MCF to subscriber A if subscriber A is a terminal DMH. After successfully completing the connection, the connection is closed and both parties communicate with each other using the SIP protocol.

In the following, subscriber B would now like to terminate the communication with subscriber A via the SIP / WLAN protocol and continue with a new protocol, such as the GSM protocol. This may be necessary if subscriber B received the SIP data via a WLAN bearer and now he would like to leave the WLAN area. For this purpose, it is provided that subscriber B actuates a button arranged on his terminal. The corresponding information for this purpose is displayed / signaled by the transmission of the identifier ID, which is transmitted again to the device MCF in the course of a GSM connection request originating from subscriber B. This is possible because the terminal device DMH has at the same time both possibilities (GSM and SIP / WLAN), and the identifier ID received via the one protocol is available within the terminal device and can pass internally to the other protocol.

The device MCF thus receives an INVITE message in which the identifier ID is inserted. In particular, it is hereby specified which part / section of the entire connection path should now be driven with the GSM protocol, that is to be replaced here by the GSM transmission protocol. According to the present exemplary embodiment, it is assumed that gone that only the connection section between the device MCF and subscriber B is driven with the GSM protocol. Between subscriber A and the device MCF, the information should continue to be transmitted using the SIP protocol (because, for example, the terminal of subscriber A supports only SIP). Of course, it is obvious that both participating participants can be equipped with terminals DMH, with which then both DMH's receive their own section between themselves and the facility MCF designated identifiers ID1 and ID2.

In the course of the change of the transmission protocol, the physical connection paths are also to be changed, over which the useful information is transmitted. The corresponding control processes are likewise carried out by the device MCF (eg with the aid of RFC3725).

As a criterion for switching here Betatigen a button on the terminal has been addressed. Another criterion would be, for example, the radio strength or similar parameters in question.

The identifier ID is generated by the device MCF. In the present case, the existing old section represented by the WLAN protocol is replaced by a new section represented by the GSM protocol. In principle, after the button has been pressed on the terminal DMH of the subscriber B, a connection is established to the device MCF. If this connection is successful (whereby in the meantime two connections (three connection sections) exist), then the existing WLAN connection will be triggered.

For realization, a new SIP header must first be defined in the SIP protocol. This has the following form (Table 1):

MCFCall-legldentifier = ("MCFCall-legldentifier") HCOLON: legident Legend = 1 * DIGIT

Tab. 1

Where MCFCall-legldentifier denotes the header name, and 1 * DIGIT the content of the header. This SIP header is now transported in the INVITE message and the following acknowledgment messages 200 OK, 18x.

In the present case, it was assumed that the second connection section is characterized by the SIP / WLAN protocol. The SIP signaling messages are thus received by the device MCF from the terminal of the subscriber A, and transmitted to the terminal of the subscriber B. 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 subscriber B is to be connected according to the present embodiment after pressing the button via the GSM protocol to the device MCF and can communicate with the A-TLN. For this purpose, a new identifier ID must also be provided in the ISUP and GSM protocol.

First, a new ISUP parameter (MCF call leg identifier parameter) is defined according to ITU-T: Q763 recommendation (Tab2):

Parameter: MCF call leg identifier: e.g. 1111 1111

Length indicator

signal:

0 0 0 0 digit 0

0 0 0 1 digit 1

0 0 1 0 digit 2

0 0 1 1 digit 3

0 1 0 0 digit 4

0 1 0 1 digit 5

0 1 1 0 digit 6

0 1 1 1 digit 7

1 0 0 0 digit 8

1 0 0 1 digit 9

1 0 1 0 to spare

1111

Filier

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

Tab. 2

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 FIG. 2), the SIP protocol is now converted into the ISUP protocol. In doing so, the identity fier of the SIP protocol into 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-legldentifier: 1234" according to SIP protocol becomes:

ISUP Parameter: 1111 11 11 Long 0000 00 10 Content 0010 00 01 21 corresponds to 12 Contents 0100 00 11 43 corresponds to 34

An ISUP parameter defined in this way is then to be transferred via the air interface to the UE mobile radio interface (GSM protocol). This is done in accordance with the recommendation TS 04.08 3GPP TS 04.08 V5.20.0 (2003-07) in a known manner. The identifier ID is simply reused and adopted according to the definition in the ISUP protocol (Q.763). The identifier of the GSM protocol should now also be provided in the protocol elements SETUP, Alerting, connect, progress.

The conversion / transfer (mapping) between ISUP and UE interface and vice versa can be done according to TS 04.08 3GPP TS 04.08 V5.20.0 (2003-07) recommendation. Here, the parameter is simply passed on to existing messages on TCAP and vice versa.

Finally, it may happen that an ISDN protocol (Q.931) is used on the section between the device MCF and the device of the subscriber B. Here as well - as in the case of the GSM protocol - a simple reuse and adoption of the parameters of the ISUP protocol (Q.763) takes place. The identifier of the ISDN protocol should now also be provided in the protocol elements SETUP, Alerting, connect, call proceeeding.

The conversion (mapping) between ISDN and ISUP and vice versa can be done by simply passing the parameters in the existing messages.

Claims

claims

A method for supporting the feature "hand off" in communication networks, wherein between a first (A) and a second subscriber (B) of the communication network, a connection is formed, which is guided 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 It is provided to each of the transmission protocols (SIP, GSM) that a switching request in the transmission protocol (GSM) of the central device (MCF) is communicated from one of the terminals (A, B) with the aid of the identifier (ID), from which then a further one Connection with the new transmission protocol (GSM) between the central device (MCF) and the initiating terminal (A, B) is controlled that Signalis ierungsdaten and bearer data of the switchover 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.

2. The method according to claim 1, characterized in that the switchover request is initiated by a multiple Ubertragungsprotocols supporting terminal (DMH).

3. Apparatus according to claim 1, 2, characterized in that the Umschaltewunsch is made in accordance with a knob on the terminal or due to the field strength / wireless quality.

4. The method according to any one of the preceding claims, characterized in that in the course of the change of the Ubertragungsprotokolls from the central device (MCF) to the Umschaltewunsch initiating terminal (DMH) optionally the physical connection paths are changed.

5. The method according to any one of the preceding claims, characterized in that the communication networks are formed as networks (FMC), which are formed from at least one fixed network portion and at least a portion of a mobile network.

6. The method according to any one of the preceding claims, characterized in that the first transmission protocol is designed as a SIP transmission protocol.

7. The method according to any one of the preceding claims, characterized in that the second transmission protocol is designed as a GSM transmission protocol.