Process for relocation of the point of diversity of a mobile station in a radio acess network

The invention relates to a method for relocating a diversity point a mobile station with features according to the preamble of claim 1 and a radio communication system with the features according to the preamble of patent claim 13.

Mobile communication systems in a core network CN, in the user and signaling data of a plurality of terminals are conveyed by wire over long distances, split and a radio access network RAN ​​(radio access network) be, which generally has a plurality of physical Network node, in particular radio network control means, includes, whose job it is, of the Terminals received data in an on for transmission the core network CN to implement suitable format and vice versa the format of the received data from the core network to the radio transmission adapt and disseminate it to that radio station, in whose coverage area the terminal equipment in question is.

Sophisticated communications systems such as cellular systems GSM (Global System for Mobile Communications) or UMTS (Universal Mobile Telecommunications System), data networks, the control of a parcel delivery protocol, in particular the Internet protocol IP subject, allowing a variety of mobile stations in parallel a radio link a network controller of the corresponding establish communications network and for data exchange to use with remote devices. To a disturbing to prevent superimposition of the signals the number of radio links, finds the respective communication between the individual mobile stations and the respectively associated network controller eg via uniquely assigned frequencies within a permanently assigned time slots and / or by means coded signals instead.

The data to be conducted include one hand data, which includes Data between two users of mobile stations are to be transmitted, and on the other signaling data, the internal to control operations of the mobile radio communication system are generated and processed. Both Types of data must be between the radio access network and a be replaced with this communicating mobile station.

In the radio access network may be between functionalities for the transmission of user data, and functionalities for are responsible to transport the signaling data, be distinguished. The former are referred to as user plane functions (User Plane Functions UPF) and the latter as a control plane functions (Control Plane Functions CPF) referred.

The present invention is described with reference to a UMTS-based Mobile Systems described. The properties However, the system according to the invention are equally applicable to GSM-based mobile systems transferable.

Each radio network controller has a plurality of User Plane Functions, which in each case within the access network an address is allocated, by means of which for a particular mobile station specific data packets to those UPF be passed, communicating with this mobile station.

The exchange of signaling protocols in the radio access network is subscriber equipment functions UEF (User Equipment Function) controlled, in a radio control server RCS (Radio Control Server) can be located, of another physical node in the radio access network RAN forms.

If a mobile station completely out of the coverage area a base station of a radio network controller moved out, it has to base station or the corresponding diversity branch of the so-called. Diversity Tree are removed, while, conversely, base stations or added taken diversity branches without transmission interruption must be, if the mobile station in the Coverage area moves into. Such a transfer mechanism, wherein the mobile station always with multiple base stations communicate, is referred to as "soft handover".

In contrast, so-called breaks when. "Hard handover" the Connection to a base station abruptly and must immediately be allocated to another base station.

The present invention enables the relocation of a mobile Station both a software and the case of a hard handover.

A known solution for the realization of the assignment or relocation the diversity point in a radio access network is described below. In Fig. 1, two states of a such a network shown. Listed are each a core network CN, the serving with a radio network controller SRNC (Serving Radio Network Controller) and a target radio network controller DRNC (Drift Radio Network Controller) connected is. To both radio network controllers DRNC and SRNC, a plurality of radio stations or base stations BS connected. The left figure shows a Situation in which a mobile station UE from the field the serving radio network controller SRNC in the range a targeted radio network controller DRNC moves while the serving radio network controller is still fully allocated.

After the illustrated radio recording with two base stations finds BS of the targeted radio network controller DRNC a data exchange of the mobile station UE to the core network CN via the radio links of the connections between the corresponding base stations BS and the targeted radio network controller DRNC, through a connection with the lur serving radio network controller SRNC and a Iu connection instead of using the core network CN and vice versa.

Once the conditions for a handover or relocation are present, takes over the previously targeted radio network controller DRNC the function of the serving radio network controller SRNC, as shown in the right figure is. The data communication of the mobile station UE with the Core network CN is now carried out directly from the mobile station UE via one of the respective base stations BS via the serving Radio network controller SRNC and via a connection Iu or vice versa.

For UMTS, version 99 was under 3GPP (3^rd generation Partnership Project) for the relocation a Relokationsfunktion with the label "Serving RNC relocation" standardized. This solution allows the exclusive use UMTS specific Protocols (3GPP TS 23.060). The previously conducted Relokationsprozedur is however relatively complicated and time consuming.

It is therefore the object of the present invention, the packet loss during a relocation of a mobile station to reduce.

This object is achieved by the process for relocating the Features of claim 1 and by a communication system for carrying out such a method according to the Features of claim 13 dissolved.

Advantageous embodiments are the subject of dependent Claims.

A method for relocating a mobile station at a low Data packet loss in a radio communications network with at least a first and a second radio network controller, wherein the management of the mobile station and / or transmitting to the mobile station data to be transmitted from the first radio network controller to the second is passed to radio network controller (handover), is particularly advantageous when data still after the handover arrive at the first radio network controller or there latched, taking advantage of a functionality the first radio network controller to a corresponding Functionality of the second radio network controller received and passed on from there to the mobile station will.

The relocation of the mobile station, that is the establishment of new transmission path between the core network and the mobile Station, is under in accordance with an embodiment of the invention Using a mobile Internet Protocol MIP performed. The currently conventional MIP standard is either IETF MIPv4 (RFC2002) or IETF MIPv6 (draft_IETF_mobileIP_Ipv6_12).

As functionality, by which the data between the two radio network control devices are received, is in particular a mobile anchor function MAF suitable. A MAF is used especially for large radio access networks, in those needed to reach the home agent too much time becomes. As a new entity MAF is, therefore, in the radio network controllers provided. In this regard, the IETF draft HMIPv4v6: draft_elmalki_soliman_HMIPv4v6_00 referenced.

As a client to perform the MIP registration of mobile Station a virtual mobile host is preferably generated.

If the mobile station itself has no virtual mobile including host, is one such example, in those created radio network controller, said serving as a (new) Radio network controller operates.

In connection with the handover a virtual mobile host set in the serving radio network controller, enables implementation in existing systems without costly structural or technical program adaptation.

The virtual host takes over as regards the re-registration and address management to the mobile station in accordance with the MIP standard intended function and also accepts preferably the function of an address memory and address manager for functionally important internal network addresses.

registered after the establishment of the virtual mobile host this preferably at the home agent, the new local Mobile anchor function and in the core network. In the solution, in which is the VMH part of the mobile station takes the proposed IETF standard HMIPs for the client function to a Registration procedure with the serving mobile anchor function be supplemented.

According to a preferred embodiment of the invention is the virtual mobile host of a radio control server RCS and especially from a user equipment function UEF, the part of the RCS is established.

To data after the handover even when the first radio network controller arrive, or stored there are still forwarded to the second radio network controller, transmitted the virtual mobile host, the address of the MAF MAF local to the first radio network controller.

The handover, ie the transfer of the administration of the second Radio network controller, is preferably by the mobile Station initiated.

According to another preferred embodiment of the invention are data that a while handing over the management of Radio network controller arrive cached.

After handing over the management of the resources mobile station in the first radio network controller, in particular the user plane function UPF deleted.

The relocation of the mobile station is preferably by means of the mobile Internet protocol MIPv6 performed.

Advantageously, a radio communication system with at least a first and a second radio network controller for managing at least one mobile station, wherein the management of the mobile station and / or the transfer to the mobile station of data to be transferred from the first radio network controller to the second radio network controller is übergebbar, the implementation of such Method, if at least one means for performing the IP registration, such as a virtual mobile host, is provided.

The invention is described with reference to the accompanying drawings exemplarily explained in more detail. Show it:<dl tsize="8"><dt>Fig. 1</dt><dd>the state of a radio network before and after a Relocation of a mobile station according to the UMTS standard, Version 99;</dd><dt>FIG. 2</dt><dd>a schematic sequence of a Relokationsprozedur according to an embodiment of the invention in an IP-based radio access network; and</dd><dt>FIGS. 3-5</dt><dd>schematically the system states in a communication network during a relocation of the diversity point a mobile station in a hard handover.</dd></dl>

As shown in FIGS. 1 and 2, the communication network represented substantially as in Fig. 1 according to FIG. 2 built communications network.

To differentiate the new technology, the radio network controllers are SRNC and DRNC referred to as-use or Intended participants levels servers S-UPS (Serving User Plane Server) or T-UPS (target user plane server) called.

The core network CN includes, inter alia, an integrated GPRS service node IGSN (Integrated GPRS service touch; GPRS: General Packet Radio Service). This serves as a gateway or Interface of the core network CN to the radio access network, which is generally is referred to as a Radio Access Network RAN. The Radio access network RAN ​​comprises a plurality here relevant institutions on, in particular, the participants levels server UPS, about the connections to fixed or mobile subscriber stations be constructed and maintained UE. the the Participants levels servers UPS are assigned base stations also part of the RAN, here not shown.

Other facilities in the radio access network RAN ​​are called. Router R, as interfaces to the so-called. IP backbone, that is Internet Protocol-controlled Pipelines or mains serve.

Furthermore, the radio access network RAN ​​comprises subscriber equipment functions UEF (User Equipment Functions) for all Operators a mobile station UE. Furthermore is in the radio access network, a home agent (Home Agent), the comparable to the home register in existing radio communication networks for registering a mobile subscriber or a mobile station UE is used.

In-use device levels servers S-UPS are in usual Way user plane functions UPF present, for Transmission of user data from one node (S-UPS) to a are responsible terminal.

In the embodiment shown here is a Relokationsverfahren proposed, in which a combination of radio-specific protocols, such as those as UMTS-specific protocols are known, with IP-based Protocols, such as those from the IETF-standardized Mobility protocol "Mobile IP Version 6 (MIPv6) "are known, can be used.

Specifically, for signaling the transition of administration the mobile station UE and / or the transfer of to the mobile station UE to be transmitted from the S-UPS the T-UPS a MIP protocol in conjunction with a protocol use of a mobile radio system.

The signaling protocols for a mobile station UE in the radio access network RAN, as already mentioned, by the called. handled user equipment function UEF.

For the relocation of a mobile station using a MIP protocol is a virtual mobile host VMH provided which serves as a client for MIP registration.

Furthermore includes the subscriber levels server UPS a mobile Anchor Function MAF over which messages from and to a mobile station UE are routed.

The sequence of a Relokationsvorgangs briefly explained with reference to FIG. 2.

If a mobile station UE in the radio access network RAN ​​by communication recording via a base station BS logs, place for this mobile station UE an IP registration the home agent HA, the local mobile anchor function MAF and the core network CN instead, so that downstream in the direction led the mobile station forwarded packets via the S-UPS will.

As long as the mobile station UE a diversity branch (diversity Leg), via which they BS with a base station is connected, the serving at the user plane server S-UPS is connected to an IP registrations carried out for the mobile station UE.

UMTS-specific mobility features are great for adding or removal of diversity branches during a soft handover responsible.

The removal of diversity branches will usually by Cell update message from the mobile station UE from initiated.

If the user equipment function UEF after removal a diversity branch detects that the last diversity branch between the mobile station UE and the serving User plane server S-UPS has been removed, which generates UEF a user plane function UPF in the targeted user plane server T-UPS, as shown in Fig. 2 by the with a 1 Arrow marked is shown.

Similarly, the user equipment function produces UEF a user plane function UPF in the targeted user plane server T-UPS when the UEF a request for a hard handover receives.

In addition, the user equipment function UEF sends the targeted user plane server UPS's message, a set up virtual mobile host VMH (this can also be part of the newly established UPF). With the help of newly created virtual host VMH, the MIP registration begin.

On the Internet protocol level (IP Layer) is the transmission path between the core network CN and the mobile station UE by a MIP registration process ( "Binding Update") changed by the new serving user plane server S-UPS is caused. It joined the virtual mobile host VMH by MIP at the local MAF as is indicated by the arrow 2, the home agent HA, as is indicated by the arrow 3, and the core network, as indicated by is the arrow 7 shown. The MIP registration can optionally also a MIP client function, the mobile in the Station UE is provided to run.

In addition, the MIP client function sends (the virtual mobile Host VMH) a connection update to the mobile anchor function (MAF) of the former serving user plane server S-UPS, whereby the downstream data transmitted to the targeted User plane server T-UPS to be redirected, as is indicated by the arrow 4th The Connection Update in particular contains the address of the mobile anchor function MAF of the targeted user plane server T-UPS.

This allows data packets that are still on the way to the old serving user plane server S-UPS are or are cached, the mobile station via the connection between the two mobile anchor function MAF always still reach (arrow 6), since this compound over a certain Time is maintained. Deleting the last Diversity branch or the last connection made only after the expiry of a changeover to the handover of the administration.

Finally, the user equipment function UEF the old serving user plane server S-UPS, resources delete for the mobile station UE (arrow 5).

With respect to the as the underlying communication system chosen as an example UMTS will respect the principles and referenced registry functions on particular MIPv6, in particular the publications IETF spec "mobility support in IPv6 ", draft-ietf-mobile IP IPv6-12. The inclusion of MIPv6 provides a number of advantages:

It allows a device, data packets to a mobile sending station UE with a fixed IP address, which fixed IP address from the actual instantaneous connection point this mobile station UE is independent of the IP network, in our case, the connection to the base station BS of the radio access network RAN. This means in particular that the participant level protocol layers above the Internet Protocol relieves IP by making changes of IP addresses will.

Furthermore MIPv6 software as commercial IP software are available, so save that development work can.

The solution described above can in a particular distributed IP-based RAN architecture may be employed in the features on the subscriber level and functions on the Control level are distributed across multiple physical nodes.

To implement the invention Relokationsverfahrens is proposed on the one hand a part of the IP-standard mechanisms talk to the Relokationsprozedur to accelerate the other hand, the UMTS functionality to modify to packet loss during Relokationsprozedur to prevent.

Hereinafter, with reference to FIGS. 3 - 5 the sequence of a relocation for the establishment of a new serving user plane server UPS explained in a hard handover.

Fig. 3 illustrates this case, the situation is, in which a first User plane server SUPS the serving user plane server and a second user plane server TUP's the targeted is user plane server. The subscriber device functions UEF are arranged in the radio control server RCS, represents one physical node. this Radio access network RAN ​​comprises a distributed architecture on. The user plane functions that individual to a mobile station UE are based, are as associated user plane functions UPFD (dedicated user plane functions) shown. These associated user plane functions UPFD are each managed in a user plane server UPS. The functional blocks VMH, PDCP, RLC, MAC, and MDF FP are sub-functions of the entity UPFD.

The associated user plane functions UPFD be corresponding control plane messages generated as above has been described.

In the core network CN, the integrated GPRS service node serves as Gateway to the radio access network RAN. The integrated GPRS service node is downstream transmitted user data in IP data packets in order that the address of the virtual mobile Hosts VMH as the destination address and the address of the integrated have GPRS service node as the source address.

The virtual mobile host has a local IP address, commonly referred to as a care-of address, and registers thus the home agent HA, the mobile anchor function MAF and the integrated GPRS service node, thereby Data transmitted in the downward direction, and in the IGSN nodes arrive, the local mobile anchor function MAF and are forwarded to the virtual mobile host. Of the VMH decapsulates the IP data packets and transmits the user data to the base station. processed in an upward direction the virtual mobile host VMH via the radio connection (via the node B) received user data and sends it directly to IGSN services node.

Starting from this system status is below the relocation the serving user plane server described.

After an activation of the mobile station UE from, stimulates the radio control server RCS the Relokationsprozedur by generating a virtual mobile host VMH at targeted User plane server T-UPS via a statement User_Plane_Setup to, as shown in Fig. 3. This statement generated terminal-specific instances in a user plane function UPFD, particular instances PDCP, RLC, MAC and VMH in the targeted user plane server T-UPS.

The radio control server also instructs the base station BS, establish a radio link. In this condition can upstream data transmitted from the mobile station UE the IGSN services node over the radio link, the base station achieve BS and the targeted user plane server T-UPS.

Downstream data transmitted, serving the former still User plane server S-UPS arrive, can not be forwarded over the radio connection and must cached in the mobile anchor function MAF of S-UPS will.

To forward the data to the mobile station, automatically sends the new virtual mobile host connection Updates (Address messages) to the MAF of the T-UPS, to the HA and the IGSN services node. In addition, the virtual sends mobile host VMH a connection update to the MAF of the S-UPS, whereby the address of the mobile anchor function MAF of the T-UPS is registered as a new care-of address. In this condition (Fig. 4) are located still on the road to S-UPS or cached data packets from the MAF of the S-UPS delivered to the MAF of the T-UPS, thus to the associated User plane function UPFD the T-UPS and mobile Station UE are forwarded.

Data packets on IGSN services node or the home agent HA (not shown) arrive, are now directly to the MAF of the T-UPS and from there forwarded to the mobile station UE.

The intended user plane server T-UPS informs the Radio control server RCS that is complete handover (As far as the T-UPS). This is done by transmission a reply UP_setup_Antwort.

As shown in Fig. 5, the radio control server deletes RCS, the associated user plane function UPFD in-use User plane server UPS after receiving the UP_setup response and then issues a message UP_freigeben from the S-UPS.

After the S-UPS has received the request UP_freigeben, it waits until corresponding buffers are empty before the former serving user plane server S-UPS the assigned User plane function UPFD including virtual mobile host VMH removed and the requirement UP_freigeben answered with a message UP_freigeben_antwort.

LIST OF REFERENCE NUMBERS

<dl tsize="5" compact="compact"><dt>UE</dt><dd>Mobile station</dd><dt>MDF</dt><dd>Macrodiversity function</dd><dt>SRNC</dt><dd>Operating end radio network controller</dd><dt>DRNC</dt><dd>Planned radio network controller</dd><dt>CN</dt><dd>core network</dd><dt>R</dt><dd>router</dd><dt>HA</dt><dd>home agent</dd><dt>UEF</dt><dd>User equipment function</dd><dt>RCS</dt><dd>Radio Control Server</dd><dt>IGSN</dt><dd>Integrated GPRS service node</dd><dt>RAN</dt><dd>Radio Access Network</dd><dt>VMH</dt><dd>Virtual mobile host</dd><dt>BS</dt><dd>base station</dd><dt>S-UPS</dt><dd>Operating Ender user plane server</dd><dt>T-UPS</dt><dd>Intended user plane server</dd><dt>UPFD</dt><dd>Assigned user plane function</dd><dt>MAF</dt><dd>Mobile anchor function</dd><dt>MAC</dt><dd>Media Access Control layer</dd></dl>