DE10109332B4 - Method for relocation of the diversity point of a mobile station in a radio access network - Google Patents

Abstract

A method for Relocation of a mobile station (UE) in a communication network, comprising a core network (CN) and a radio communication network (RAN) with at least a first and second radio network controller (UPS), wherein the management of the mobile station (UE) and / or the transfer of data to be transmitted to the mobile station (UE) from the first radio network controller (S-UPS) to the second radio network controller (T-UPS) is handover,
- The data that arrive after a successful handover to the first radio network controller (S-UPS) or are cached there, using a mobile anchor function (MAF) of the first radio network controller (S-UPS) to a corresponding mobile Anchor function (MAF) of the second radio network controller (T-UPS) and forwarded from there to the mobile station (UE),
In which the transmission path between the core network (CN) and the mobile station (UE) is changed during a handover using a mobile internet protocol (MIP) (MIP registration),
- As a client to perform a MIP registration, a virtual mobile host (VMH) in the second ...

Description

The The invention relates to a method for relocation of a diversity point a mobile station having features according to the preamble of the claim 1 and a radio communication system with the features according to the preamble of claim 9.

Mobile communication systems can in a core network CN in which payload and signaling data of a plurality of terminals over long distances transported by cable and a radio access network RAN which is generally a plurality of physical Network node, in particular radio network control devices, comprises, whose Task is it, of the terminals received data in a for the transfer on the core network CN suitable format to implement and vice versa Format of the data received from the core network to the radio transmission adapt and forward to the radio station in whose Sendbereich the respective terminal is located.

sophisticated Communication systems, such as e.g. Mobile radio systems GSM (Global System for Mobile Communications) or UMTS (Universal Mobile Telecommunications System) and data networks, the control of a parcel shipping protocol, in particular subject to the Internet Protocol IP, allow a variety of mobile stations parallel to each other a radio connection via a network control device of the appropriate communication network and build for a Use data exchange with remote facilities. To one disturbing overlay To prevent the signals of the many radio links, finds the respective communication between each mobile station and the respective associated network controller, e.g. about clearly associated frequencies within fixed time slots and / or with the aid of coded signals.

The The data to be routed comprises on the one hand user data, i. Data that between two users of mobile stations, and on the other hand Signaling data used to control internal processes of the Mobile radio communication system be generated and processed. Both types of data must be in between the radio access network and a mobile station communicating with it be replaced.

in the Radio access network can be used between functionalities necessary for the transmission of user data, and functionalities the for the transport of the signaling data are responsible, can be distinguished. The former are called subscriber plane functions (User Plane Functions UPF) and the latter as control plane functions (CPF) designated.

The The present invention will be described below with reference to a UMTS-based mobile radio system. However, the properties of the system according to the invention are also the same transferable to GSM-based mobile radio systems.

each Radio network controller has a Plurality of User Plane Functions, each within the access network an address is assigned with the help of which for a particular mobile station certain data packets are routed to the UPF with This mobile station communicates.

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

If a mobile station turns off completely the coverage area a base station of a radio network controller moved out, must this base station or the corresponding diversity branch from the so-called diversity tree be removed while reversed base stations or diversity branches without transmission interruption have to be added when the mobile station moves into its coverage area. Such a transfer mechanism, at the mobile station always communicates with multiple base stations, is called "soft handover ".

in the In contrast, the connection breaks in a so-called "hard handover" one base station abruptly and must immediately to another Base station be transferred.

The present invention enables the relocation of a mobile station in both a soft- and even with a hard handover.

A known solution for realizing the allocation or relocation of the diversity point in a radio access network will be described below. In 1 two states of such a network are shown. In each case, a core network CN is shown, which is connected to a serving radio network controller SRNC (Serving Radio Network Controller) and a destination radio network controller DRNC (Drift Radio Network Controller). To both radio network controllers DRNC and SRNC is connected to a plurality of radio stations or base stations BS. The left figure shows a situation in which a mobile station UE moves from the area of the serving radio network controller SRNC into the area of a targeted radio network controller DRNC and is still fully associated with the serving radio network controller.

To the illustrated radio subscription with two base stations BS of envisaged radio network controller DRNC finds a data exchange the mobile station UE with the core network CN via the radio links, via the Connections between the corresponding base stations BS and the envisaged radio network controller DRNC, via a connection Iur with the serving radio network controller SRNC and via a Connection Iu with the core network CN or vice versa.

As soon as the conditions for a transfer or Relocation, takes over the previously targeted radio network controller DRNC performs the function the serving radio network controller SRNC, as in the right Illustration is shown. The data communication of the mobile station UE with the core network CN now takes place directly from the mobile station UE over one of the corresponding base stations BS, via the serving radio network controller SRNC and over a connection Iu or vice versa.

For UMTS, version 99, a relocation function called "Serving RNC relocation" was standardized under 3GPP (3 ^rd Generation Partnership Project) for the relocation, allowing the exclusive use of UMTS-specific protocols (3GPP TS 23.060) however, is relatively complicated and time consuming.

From "Route Optimization in Mobile IP ", Perkins and Johnson, Mobile IP Working Group, Internet Draft, "draft-ietf-mobileip-optim-10.txt", 15 November 2000, is a method of transmission known by "Datagrams", where "datagrams" of a "correspondent node "to a" mobile node "bypassing a assigned "home agents" transmit to the transmission path to optimize. Datagrams associated with the previously assigned "foreign agent of the mobile nodes "on the way are forwarded to a so-called "new care-of address".

From "Hierarchical MIPv6 mobility management (HMIPv6) ", H. Soliman et al., Mobile IP Working Group, INTERNET DRAFT, "draft-ietf-mobileip-hmipv6-02.txt", November 2000 a so-called "mobility Anchor Point "known that in any level of the hierarchical mobile IPv6 network introduced and used to handle a handover.

It Object of the present invention, the data packet loss during a Reduce relocation of a mobile station.

These Task is by the method of relocation with the features of the patent claim 1 and by a communication system for carrying out a such method according to the features of claim 9 solved.

advantageous Embodiments are the subject of dependent claims.

One Method for relocation of a mobile station with low data packet loss in a radio communication network with at least a first and a second radio network controller, wherein the management of the mobile station and / or the transmission from the mobile station to be transmitted Transferring data from the first radio network controller to the second radio network controller is (handover), is particularly advantageous when data after the handover still arrive at the first radio network controller or cached there, taking advantage of a functionality of the first Radio network controller to a corresponding functionality of the second Radio network controller transmitted and from there to the mobile station forwarded.

The Relocation of the mobile station, i. the establishment of the new transmission path between the core network and the mobile station, according to a Development of the invention using a mobile Internet Protocol MIP performed. The currently usual MIP standard is either IETF MIPv4 (RFC2002) or IETF MIPv6 (draft_IETF_mobileIP_Ipv6_12).

When functionality by means of which the data is transmitted between the two radio network control devices In particular, a mobile anchor function MAF is suitable. A MAF is used in particular for large radio access networks, in which too much time is needed to reach the home agent. As a new entity Therefore, a MAF is provided in the radio network controllers. This will be to the IETF draft HMIPv4v6: draft_elmalki_soliman_HMIPv4v6_00 directed.

When Client to carry out MIP registration of the mobile station is preferably one generated virtual mobile host.

Provided the mobile station itself does not have a virtual mobile host, becomes such as, for example, in the radio network controller created as a (new) serving wireless network controller acts.

In Connecting to the handover a virtual mobile host in the set up serving radio network controller allows implementation in existing systems without complex structural or programming technology Adaptation.

Of the virtual host takes over Regarding the re-registration and address management of the mobile Station according to the MIP standard intended function and takes over Furthermore preferably the function of an address memory and address manager for functionally important network internal addresses.

To the virtual mobile host device registers itself preferably at the home agent, the new local mobile anchor function and in the core network. In the solution, in which the VMH is part of the mobile station, the planned IETF standard HMIP for the client function is a registration process with the operator added mobile anchor function become.

According to one preferred embodiment of the invention is the virtual mobile Host from a radio control server RCS and in particular one Subscriber device function UEF, which is part of the RCS, set up.

Around Data after handover still at the first radio network controller arrive, or are cached there, still to the second Forwarding radio network controller, transmits the virtual mobile Host the address of the local MAF to the MAF of the first radio network controller.

The handover, i. the handover management to the second radio network controller is preferred initiated by the mobile station.

According to one Another preferred embodiment of the invention is data that while the handover the management arrive at a radio network controller, cached.

To the handover The administration will use the resources of the mobile station in the first radio network controller, in particular the subscriber level function UPF deleted.

The Relocation of the mobile station is preferably by means of the mobile internet protocol MIPv6 performed.

advantageously, allows 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 from the mobile station to be transmitted Data from the first radio network controller to the second radio network controller transferable is the implementation of such a procedure, if at least one Device for performing IP registration, e.g. a virtual mobile host is.

The Invention will be exemplified below with reference to the accompanying drawings explained in more detail. It demonstrate:

1 the state of a radio network before or after a relocation of a mobile station according to the UMTS standard, version 99;

2 a schematic sequence of a Relokationsprozedur according to an embodiment of the invention in an IP based radio access network; and

3 - 5 schematically the system states in a communication network during a relocation of the diversity point of a mobile station in a hard handover.

Like from the 1 and 2 As can be seen, the communication network is according to 2 essentially like that in 1 illustrated communication network constructed.

to Discrimination of the new technology will be the radio network controllers SRNC or DRNC subsequently as a serving subscriber level server S-UPS (Serving User Plane Server) or T-UPS (Target User Plane Server) designated.

The Core network CN has u.a. an integrated GPRS service node IGSN (Integrated GPRS Service node; GPRS: General Packet Radio Service). This serves as Gateway or interface of the core network CN to the radio access network, commonly referred to as Radio Access Network RAN. The Radio access network RAN has a variety of relevant facilities here on, in particular, the subscriber level server UPS, via the Connections with stationary or mobile subscriber stations UE are established and maintained. The base stations assigned to the subscriber level servers UPS are also part of the RAN, but not shown here.

Further Devices in the radio access network RAN are so-called routers R, which are known as Interfaces to the so-called IP backbone, ie Internet protocol-controlled transmission lines or main lines serve.

Farther The radio access network RAN comprises subscriber device functions UEF (User Equipment Functions) for all signaling of a mobile station UE. Further located in the radio access network a home agent (home agent), the comparable to the home location register in existing radio communication networks for registration a mobile subscriber or a mobile station UE is used.

in the Serving Subscriber Level Servers S-UPS are in common Way subscriber level functions UPF available for the transmission of User data from a node (S-UPS) to a terminal responsible are.

at the embodiment shown here a relocation method is proposed in which a combination radiospecific protocols, such as UMTS-specific Protocols are known using IP-based protocols, such as those standardized from the IETF Mobility Protocol "Mobile IP version 6 (MIPv6) "known are to be used.

Especially becomes the signaling of the transition the management of the mobile station UE and / or the transmission from the mobile station UE to be transmitted Data from the S-UPS to T-UPS a MIP protocol in conjunction with a protocol used by a mobile system.

The Signaling protocols for a mobile station UE are in the radio access network RAN, as already mentioned, handled by the so-called subscriber device function UEF.

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

Of Further, the subscriber level server UPS includes a mobile anchor function MAF, about the messages are routed to and from a mobile station UE.

In the following, the sequence of a Relokationsvorgangs is briefly based on 2 explained.

If a mobile station UE in the radio access network RAN by a communication recording via a Base station BS logs finds for this mobile station UE a IP registration at home agent HA, the local mobile anchor feature MAF and the core network CN instead, so that downstream towards the mobile Station conducted data packets via the S-UPS will be routed.

So long the mobile station UE has a diversity leg over which it is connected to a base station BS, which is connected to the serving Participant level server S-UPS is connected, no IP re-registrations for the mobile Station UE made.

UMTS-specific mobility features are for The addition or removing diversity branches while a softhandover responsible.

The Removal of diversity branches is usually generated by cell update messages from the mobile Station UE from initiated.

When the subscriber facility function UEF detects, after removing a diversity branch, that the last diversity branch between the mobile station UE and the serving subscriber level server S-UPS has been removed, the UEF generates a subscriber level function UPF in the targeted subscriber level server T-UPS, as in FIG 2 by the one with 1 marked arrow is shown.

In similar Manner, the subscriber facility function UEF generates a subscriber level function UPF in the targeted subscriber level server T-UPS if the UEF has a Requirement for a hard handover receives.

Also sends subscriber device function UEF to the targeted subscriber level server UPS the message, a virtual mobile host VMH set up (this may also be part of the newly established UPF). With the help of the newly created virtual host VMH, the MIP registration can begin.

At the Internet Protocol (IP) layer, the transmission path between the core network CN and the mobile station UE is changed by a Binding Update process initiated by the new serving subscriber level server S-UPS virtual mobile host VMH using MIP at the local MAF, as indicated by the arrow 2 is displayed at home agent HA, as indicated by the arrow 3 is displayed, and at the core network, as indicated by the arrow 7 is displayed. Optionally, the MIP registration may also be performed by a MIP client function provided in the mobile station UE.

In addition, the MIP client function (the virtual mobile host VMH) sends a connection update to the mobile anchor function (MAF) of the former Serving subscriber level server S-UPS, whereby the downstream transmitted data to the targeted subscriber level server T-UPS are redirected, as indicated by the arrow 4 is marked. Specifically, the connection update includes the address of the mobile anchor function MAF of the targeted subscriber level server T-UPS.

As a result, data packets that are still on the way to the old serving subscriber level server S-UPS or cached, the mobile station via the connection between the two mobile anchor functions MAF still reach (arrow 6 ), because this connection is maintained over a period of time. The deletion of the last diversity branch or the last connection takes place only after the expiry of a switching time after the transfer of the administration.

Finally, the subscriber facility function UEF instructs the old serving subscriber level server S-UPS to clear the resources for the mobile station UE (arrow 5 ).

With regard to the UMTS exemplarily chosen as the underlying communication system, reference is made in particular to MIPv6 with regard to the principles and registration functions, in particular to the publications IETF spec "mobility support in IPv6", draft-ietf-mobile IP-IPv6-12. The integration of MIPv6 offers a multitude of advantages:
It allows a device to send data packets to a mobile station UE with a fixed IP address, this fixed IP address being independent of the actual instantaneous connection point of this mobile station UE to 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 subscriber-level protocol layers above the Internet Protocol IP are relieved of making changes to IP addresses.

Farther MIPv6 software is available as commercial IP software, so that development work can be saved.

The solution described above especially in a distributed IP based RAN architecture be used in the functions at the subscriber level and Functions at the control level via several physical nodes are distributed.

to Implementation of the relocation method according to the invention It is proposed, on the one hand, to exchange part of the IP standard mechanisms in order to: to accelerate the relocation procedure and to modify the UMTS functionality, around packet losses during prevent the Relokationsprozedur.

The following is based on the 3 - 5 the process of relocation for setting up a new serving subscriber level server UPS during a hard handover.

3 represents the situation in which a first subscriber level server SUPS is the serving subscriber level server, and a second subscriber level server TUPS is the targeted subscriber level server. The subscriber device functions UEF are arranged in the radio control server RCS, which represents a physical node. The present radio access network RAN has a distributed architecture. The subscriber level functions related to a single mobile station UE are shown as dedicated user plane functions (UPFd). These associated subscriber level functions UPFd are each administered in a subscriber level server UPS. The functional blocks VMH, PDCP, RLC, MAC, MDF and FP are subfunctions of the entity UPFd.

The assigned subscriber level functions UPFd are by appropriate Control plane messages generated as described above.

in the Core network CN is the integrated GPRS service node as gateway to the radio access network RAN. The integrated GPRS service node sets downstream transmitted User data in IP data packets at which the address of the virtual mobile Hosts VMH as the destination address and the address of the integrated GPRS service node as the source address.

Of the virtual mobile host has a local IP address, usually is referred to as a care-of-address and registers with the home agent HA, the MAF mobile anchor function, and the integrated GPRS service node, causing data to be transmitted in the downlink and arrive at the IGSN node, to the local mobile anchor function MAF and forwarded to the virtual mobile host. The VMH decapsulates the IP data packets and transmits the user data to the base station. In the upward direction the virtual mobile host VMH processes the data via the radio connection (via the Node B) received user data and sends it directly to the IGSN service node.

outgoing from this system state is subsequently the relocation of the serving Participant level server described.

After activation by the mobile Sta tion UE, the radio control server RCS the Relokationsprozedur by generating a virtual mobile host VMH at anvi sierten subscriber level server T-UPS via a statement User_Plane_Setup on, as in 3 is shown. This instruction generates terminal-specific instances in a subscriber level function UPFd, in particular the instances PDCP, RLC, MAC and VMH in the targeted subscriber level server T-UPS.

Of the Radio control server also commands the base station BS, a radio link to set up. In this state, upstream transmitted Data from the mobile station UE to the IGSN service node via the Radio connection, the base station BS and the targeted subscriber level server Reach T-UPS.

Downstream transmitted Data still on the formerly serving subscriber level server S-UPS can arrive not over the radio link must be forwarded and in the mobile anchor function MAF of the S-UPS are cached.

To forward the data to the mobile station, the new virtual mobile host automatically sends connection updates (address messages) to the MAF of the T-UPS, the HA, and the IGSN service node. In addition, the virtual mobile host VMH sends 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 ( 4 ), the data packets still on the way to the S-UPS or cached are transmitted by the MAF of the S-UPS to the MAF of the T-UPS, whereby they are forwarded to the assigned subscriber level function UPFd in the T-UPS and to the mobile station UE.

Data packets at the IGSN service node or home agent HA (not shown) arrive now directly to the MAF of the T-UPS and from there to the mobile Headed by the UE station.

Of the targeted subscriber level server T-UPS informs the remote control server RCS that the handover is completed (as far as the T-UPS is concerned). This happens through transmission a response UP_setup_response.

As in 5 is shown, the radio control server RCS deletes the associated subscriber level function UPFd in the serving subscriber level UPS UPS after receiving the UP_setup response and then issues a UP_enable message to the S-UPS.

After this the S-UPS has received the request UP_freigeben, it waits, until corresponding buffer stores are empty, before the former serving Subscriber level server S-UPS the assigned subscriber level function Including UPFd of the virtual mobile host VMH and release the request UP_ answered with a message UP_freigeben_antwort.

Claims (9)

Method for relocation of a mobile station (UE) in a communication network comprising a core network (CN) and a Radio communication network (RAN) with at least a first and second Radio network controller (UPS), the management of mobile Station (UE) and / or the transmission of to the mobile station (UE) Data from the first radio network controller (S-UPS) to the second Radio network controller (T-UPS) can be handed over (handover), - in which Data after a successful handover to the first radio network controller (S-UPS) arrive or are cached there, taking advantage of it a mobile anchor function (MAF) of the first radio network controller (S-UPS) to a corresponding Mobile Anchor Function (MAF) of the second radio network controller (T-UPS) and from there to the mobile station (UE), - in which the transmission route between the core network (CN) and the mobile station (UE) in a handover is changed using a Mobile Internet Protocol (MIP) (MIP registration) - at as a client a MIP registration a virtual mobile host (VMH) in the second radio network controller (T-UPS) is generated. The method of claim 1, wherein an MIP client in the mobile station (UE) or the virtual mobile host (VMH) in a serving radio network controller (UPS) at a local Mobile Anchor Function (MAF) at a home agent (HA) and registered in the core network (CN). The method of claim 1 or 2, wherein the generation of the virtual mobile host (VMH) through a radio control server (RCS), in particular by a provided in the radio control server (RCS) Subscriber device function (UEF) is initiated. Method according to one of the preceding claims, in the MIP client or virtual mobile host (VMH) the address the Mobile Anchor Function (MAF) of the Second Radio Network Controller (T-UPS) to the Mobile Anchor Function (MAF) of the first radio network controller (S-UPS). Method according to one of the preceding Claims in which handover is initiated by the mobile station (UE). Method according to one of the preceding claims, in during that the handover the administration or the transfer data between the wireless network controllers (S-UPS, T-UPS) at the second radio network controller (T-UPS) incoming data cached become. Method according to one of the preceding claims, in after setting up a Subscriber Level Function (UPF) in the second radio network controller (T-UPS) the resources for the mobile Station (UE), in particular the subscriber level function (UPF), in the first radio network controller deleted becomes. Method according to one of the preceding claims, in to signal the transition the management of the mobile station (UE) (handover) and / or the transmission from the mobile station (UE) to be transmitted Data MIP-V6 is used. Radio communication system with at least a first and a second radio network controller (UPS) for management at least one mobile station (UE), wherein the management of the mobile station (UE) and / or the transmission from the mobile station to be transmitted Data from the first radio network controller (S-UPS) to the second radio network controller (T-UPS) can be handed over is characterized by means for carrying out the Method according to one of the claims 1 to 8.