Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W8/00—Network data management
  • H04W8/02—Processing of mobility data, e.g. registration information at HLR [Home Location Register] or VLR [Visitor Location Register]; Transfer of mobility data, e.g. between HLR, VLR or external networks
  • H04W8/06—Registration at serving network Location Register, VLR or user mobility server

Definitions

• the present invention relates to a method of performing roaming of a subscriber between networks and also relates to a corresponding device.
• the present invention is directed to a method and corresponding device being used when a circuit switched (CS) subscriber, like a subscriber of a 2G (second generation) telecommunication network roams from one telecommunication network, like the 2G telecommunication network, to a packed switched (PS) network, like a 3G (third generation) telecommunication network.
• CS circuit switched
• PS packed switched
• Mobile telecommunication systems such as the Global System for Mobile Communications GSM, the Universal Mobile Telecommunications System UMTS, and the like, have a cellular structure comprising several cells. For each cell at least one transceiver station (base station) is provided. Via this base station, a user equipment of a subscriber and elements of the telecommunication system (network elements such as exchange stations and registers) communicate. The subscriber is free to move within the network from one cell to another without loosing contact (handover) .
• base station For each cell at least one transceiver station (base station) is provided. Via this base station, a user equipment of a subscriber and elements of the telecommunication system (network elements such as exchange stations and registers) communicate. The subscriber is free to move within the network from one cell to another without loosing contact (handover) .
• the coexisting networks may be of different types.
• one network e.g. the home network
• the other network e.g. GSM
• the visited network is a 3G (third generation) network (e.g. UMTS).
• the respective networks may offer different service types and/or communication modes, attention has to be paid to the establishment of a correct connection and communication paths, when e.g. a 2G subscriber wishes to roam into the 3G network.
• the circuit switched (CS) transmission type uses one transmission resource (e.g. one channel) for a communication until ending the communication.
• packet switched transmission has been developed. Here, data are collected in a buffer and then sent as one packet via a requested transmission resource to an indicated address.
• CS transmission is used.
• packet switched system like the Generalized Packet Radio Service GPRS for GSM networks, are added in order to enable the usage of both transmission types for the subscribers. That is, there can be networks and/or subscribers either supporting only one of these transmission types (namely the "traditional" CS type) or both types (CS and PS type) . In the latter case, the subscriber may select which mode is to be used, when both are available from a network.
• 3G networks and correspondingly 3G subscribers (i.e. user terminals) are designed to perform both CS and PS transmission communications.
• 3G networks such as the UMTS, offers specific communication modes.
• VoIP Voice over Internet Protocol
• VoIP Voice over Internet Protocol Due to the similarity to a CS communication, it is also possible that 3G networks are designed to support the usage of VoIP services by CS subscribers.
• a subscriber with only CS capability may roam into the 3G network.
• the roaming subscriber requests to use the VoIP communication mode, it has to be decided in the 3G network, on the basis of which kind the subscriber is (CS only, CS and packet switched, and the like) , which operations in the network has to be executed in order to establish a proper communication connection for the subscriber.
• This may include for example transport layer registration or transport layer access, application layer registration or application layer access, authentication mechanisms, subscriber profile creations and the like.
• a transport layer registration is performed to define relevant data structures, communication protocols, Quality of Service (QoS) and the like.
• the transport layer registration is made by the 2G subscriber e.g. by a PS attach (e.g. GPRS attach) to the 3G network and a GPRS location update to the 2G network.
• a PS attach e.g. GPRS attach
• the transport layer registration is completed in the 3G network wherein the GPRS profile of the subscriber created and used in the GPRS location update depends on whether the subscriber is a CS only subscriber (option I: M204A, M205A) or a CS and PS subscriber (option II: M204B, M205B) .
• a packet data protocol (PDP) context activation is executed between the 2G subscriber and the 3G network.
• PDP packet data protocol
• an application level registration is executed to define the connection parameters (e.g. VoIP, All-IP) , wherein an normal location update at the 3G network and the 2G network is performed.
• this object is achieved by a method of performing roaming of a subscriber using a first transmission type from a first network to a second network being based on a second transmission type, said method comprising a first registering step for registering said subscriber in said second network on the basis of one of said first and said second transmission types, and in the case that said first registering step fails, a second registering step for registering said subscriber in said second network on the basis of the other of said first and said second transmission types.
• the present invention proposes a device for performing roaming of a subscriber using a first transmission type from a first network to a second network being based on a second transmission type, said device is adapted to perform a first registration of said subscriber in said second network on the basis of one of said first and said second transmission types, and in the case that said first registration fails, a second registration of said subscriber in said second network on the basis of the other of said first and said second transmission types.
• the proposed method and/or device are easy to implement. Since the required functions can be executed by one network element, namely the roaming element such as a roaming signaling gateway functionality element R-SGW of the 3G network, and changing or adaptation of other network elements (e.g. of 2G or 3G networks) is not necessary.
• the present invention can be implemented by software, but also a hardware solution with a corresponding circuitry can be used.
• One further advantage of the present invention is that the signaling load of the network in certain situations is reduced. Namely, when , for example, the 2G network indicates that no subscription for the requested transport layer is present, the roaming element immediately starts a normal location update towards the registration element of the home network of the subscriber, e.g. the 2G home location register, or ends the transaction immediately. When the 2G network does not accept the location update, e.g. since the subscriber is not allowed to roam to the 3G network, the transaction is cancelled before the transport layer access is completed and an application layer access in the 3G network is started.
• the roaming element as a buffer for storing the subscriber data (e.g. the subscriber profile) sent by the 2G registration element when the normal location update is accepted, a further contacting of the 2G network during the execution of the normal location update procedure in the 3G network at the application layer registration can be avoided. It is possible to buffer the subscriber data merely for a predetermined period of time so as to reduce the required memory capacity. However, when the data are needed after said predetermined period of time (i.e. after they are cleared), the data can be fetched again from the 2G network.
• the subscriber data e.g. the subscriber profile
• Fig. 1 shows a block circuit diagram illustrating a network environment with network elements used in the present invention.
• Figs. 2A, 2B and 2C show flow charts illustrating an embodiment of the method according to the present invention.
• Figs. 3A and 3B show diagrams illustrating the signaling between the network elements shown in Fig. 1 according to the present invention.
• Figs. 4A and 4B show diagrams illustrating the signaling between the network elements shown in Fig. 1 according to the prior art.
• Fig. 1 is a block circuit diagram illustrating network structures of a 2G network 2 and a 3G network 5 as an illustrative example, in which the present invention is implemented. It is to be noted that for the sake of simplicity only network elements are shown which are directly involved. As commonly known, telecommunication network systems also comprise further elements such as a base station subsystem (BSS) comprising transceiver stations, registers, and the like, which are used for communications. The complete network structures as well as corresponding interconnections can be found e.g. in the GSM specifications and the UMTS specifications, respectively. Furthermore, it is to be noted that the described 2G/3G situation is only for illustration. A GPRS system can be part of the 2G network or existing in parallel.
• BSS base station subsystem
• the described method and/or device are applicable in general to situations in which a subscriber using a first transmission type roams to a network using a second transmission type, for example in the case that a CS subscriber roams to an all IP network, or the like.
• the 2G network 2 comprises a first switching element 3 such as a mobile switching center MSC (including a visitor location register VLR) and a registration element 4 such as a home location register HLR (including an authentication center AuC) .
• the MSC/VLR 3 serves a 2G subscriber 1 (represented by a user equipment/mobile station UE/MS) for controlling calls in the 2G network 2.
• the HLR 4 is used for storing subscriber data as well as for updating location information of the subscriber 1, and the like.
• the 3G network 5 comprises switching elements such as an enhanced serving GPRS support node E-SGSN 6, an enhanced gateway GPRS support node E-GGSN 7, a control element such as a call state control function element CSCF 8 and a roaming element such as a roaming signaling gateway element R-SGW 9.
• switching elements such as an enhanced serving GPRS support node E-SGSN 6, an enhanced gateway GPRS support node E-GGSN 7, a control element such as a call state control function element CSCF 8 and a roaming element such as a roaming signaling gateway element R-SGW 9.
• the E-SGSN 6 serves the subscriber in packet switched communication and establishes e.g. a mobility management context, containing information pertaining to mobility and security for the subscriber, and a PDP context.
• the E-GGSN 7 serves for packet switched communication and interconnection with other telecommunication networks.
• the E-SGSN and E-GGSN may be combined in one unity. Both comprise IP routeing functionality.
• the CSCF 8 is used to perform call state control functions in the 3G network, such as an incoming call gateway function ICGW, a call control function CCF (e.g. processing of application layer registration) , an address handling AH, and the like.
• call state control functions such as an incoming call gateway function ICGW, a call control function CCF (e.g. processing of application layer registration) , an address handling AH, and the like.
• the functionality of the R-SGW 9 is related to roaming of e.g. 2G/R99 (CS only and CS/GPRS) subscribers to/from e.g. a 3G/R00 UMTS teleservices domain and UMTS GPRS domain.
• the R-SGW performs a signaling conversion at transport level (e.g. to IP based transport signaling) .
• R-SGW 9 and the HLR/AuC 4 are usually not directly connected, as indicated by the dotted arrow in Fig. 1, but they are connected via several interconnecting and gateway elements known by a person skilled in the art, which are omitted in order to simplify the figure.
• a subscriber e.g. a 2G/R99 subscriber
• a 3G network such as Voice over IP or the like
• roaming from the 2G home network 2 to a 3G network 5 is to be performed.
• the E-SGSN 6 is contacted by said subscriber 1 in order to initialize a transport layer access (or transport layer registration) for using e.g. a packet switched communication such as
• GPRS attach To indicate its presence and intention to roam in the 3G network, a GPRS attach (PS attach) is sent from the user equipment of the subscriber 1 to the 3G network, which comprises for example the International Mobile Subscriber Identity IMSI (step S2; message M101) .
• IMSI International Mobile Subscriber Identity
• an authentication procedure using a GPRS mechanism is performed in the 3G network, in which the subscriber identity is checked (step S3; message M102) .
• the E-SGSN 6 sends a GPRS location update message including the IMSI and the identification number of the E- SGSN 6 to the R-SGW 9 which in turn contacts the HLR/AuC 4 of the 2G network 2 (step S3; message M103) .
• This message M103 is sent e.g. by using a MAP (mobile application part) application context GPRS location update context.
• the further processing depends on processing results of the HLR 4 concerning the GPRS location update from the 3G network. Namely, the HLR 4 checks whether it supports the application context GPRS location update context (message M103) , and whether the subscriber 1 has a subscription for GPRS. If YES (step S4), i.e. the subscriber has a PS subscription in the HLR 4 meaning that he/she is e.g. an 2G/R99 CS and GPRS subscriber, a procedure may follow which corresponds to the steps shown in Figs. 4A and 4B, option II (i.e. messages M204B to M217).
• YES i.e. the subscriber has a PS subscription in the HLR 4 meaning that he/she is e.g. an 2G/R99 CS and GPRS subscriber
• step S10 the HLR 4 accepts the GPRS location update and sends a corresponding message comprising the IMSI and the 2G/R99 profile of the subscriber 1 to the R-SGW 9.
• the 3G network modifies the subscriber profile in such way that the requested transport layer for the requested service (for example GPRS for VoIP) can be used.
• the new subscriber profile is sent to the E-SGSN 6, which in turn contacts the subscriber 1 in order to accept the GPRS attach.
• the GPRS location update is completed and the transport layer registration is confirmed.
• a PDP context activation is performed in the 3G network 5.
• an application layer access or application layer registration
• a normal location update between the 3G network 5 and the 2G network 2 is executed.
• the subscriber 1 sends a resource request RRQ comprising subscriber information for the application layer (ALSI) to the CSCF 8 in order to initialize an application layer registration.
• the RRQ message can be, for example, a H.323 protocol message, a session initiation protocol (SIP) message, or the like.
• SIP session initiation protocol
• a location update message comprising the ALSI and the CSCF address is sent from the CSCF 8 to the R-SGW 9.
• the R-SGW 9 forwards the location update message including an R-SGW identification number to the HLR 4.
• the HLR 4 cancel the location of the subscriber 1 in the 2G network (i.e. at the MSC/VLR 3) and sends a location update reply message comprising the 2G profile of the subscriber to the R-SGW 9.
• a new connection profile e.g. an All-IP profile
• the new connection profile is transmitted to the CSCF 8 by means of a location update reply message.
• the CSCF then completes the application layer registration and the normal location update (step S13) by transmitting a resource confirmation RCF message to the user equipment of the subscriber 1 in order to acknowledge the registration.
• the RCF message is, similar to the RRQ message mentioned above, for example, a H.323 protocol message, a session initiation protocol (SIP) message, or the like.
• the R-SGW 9 checks •'the message content from the HLR 4 to decide whether the transaction has to be ended in this stage (step S5) .
• the GPRS location update is not acceptable by the HLR 4.
• the 2G HLR 4 does not support the application context GPRS location update context used in message M103.
• the message returned to the R-SGW 9 represents an application context not supported message (in correspondence with message M104).
• This circumstance however also represents the fact that the subscriber 1 has no GPRS subscription.
• the subscriber 1 is known by the 2G HLR 4, which supports the application context GPRS location update context used in message M103, but the GPRS subscription is unknown.
• an initialization of a normal location update is performed by the R-SGW 9 (step S6, to be described below) .
• step S5 can be omitted (e.g. since a processing of the message IMSI unknown is not performed in this stage) . That is, a normal location update is initialized in any case.
• the transaction is ended after a further processing (normal location update, step S ⁇ ) as in the case that the subscriber has no permission to roam to a 3G network (described below) .
• This latter procedure option would standardize the processing in the R-SGW 9.
• the R-SGW 9 When the reason for not accepting the GPRS location update results not in an immediate end of the transaction in step S5, the R-SGW 9 initializes immediately a normal location update towards the 2G network. This comprises the re- contacting of the HLR 4 and the sending of the IMSI and the R-SGW identification number (step S6; message M105) .
• the HLR 4 checks whether it can accept a normal location update of the subscriber (step S7) . That is, for example, it is checked whether the subscriber 1 is known to HLR (i.e. is the subscriber identity deleted from the database) , or a prohibition to roam in a 3G network is present, or the like. In the case that the HLR 4 indicates to the R-SGW 9 that the normal location update of the subscriber 1 is not accepted, and the R-SGW 9 sends an error message to the 3G network in order to indicate that the subscriber 1 can not roam to the 3G network. It is also possible to forward a corresponding error message to the subscriber 1. Then, the roaming transaction is terminated.
• the HLR 4 decides that a location update of the subscriber 1 is acceptable, the location in the 2G network 2 (i.e. in the MSC 3) is cancelled (S20; M106) .
• a location update reply is sent to the R-SGW 9 including the 2G profile of the subscriber 1 (M107).
• step S4 since the subscriber 1 has no GPRS subscription as determined in step S4, a "default" GPRS profile is created (step S21; M108) with a real-time
• the 2G profile (2G GPRS profile, 2G CS service information, or the like) may be mapped to 3G services.
• the profile is stored in the R-SGW 9, wherein the subscriber database is indexed by the IMSI. It is possible to provide a link for each subscriber to one "default" profile, or one individual profile is stored for each subscriber.
• the new "default" GPRS profile is sent to the E-SGSN 6 (M109) , which forwards a GPRS attach reply to the user equipment of the subscriber 1 (MHO) .
• the GPRS location update is completed and the transport layer registration is confirmed (step S21) .
• a PDP context activation is performed between the user equipment of the subscriber 1 and the 3G network (Mill) .
• an application layer registration is executed, wherein a normal location update between the 3G network 5 and the 2G network 2 is executed (M112) .
• the subscriber 1 sends the resource request RRQ comprising subscriber information for the application layer (ALSI) to the CSCF 8 in order to initialize the application layer registration.
• a location update message comprising the ALSI and the CSCF address is sent to the R-SGW 9 (M114) .
• the R-SGW 9 reads the buffered 2G profile of the subscriber 1 from said buffer means, and a new connection profile (e.g. an All-IP profile) is created in the 3G network by using the 2G profile in order to enable an establishment of the requested connection mode (step S23; M115) .
• a re- contacting of the 2G network i.e. of the HLR 4 is not required.
• the new connection profile is transmitted to the CSCF 8 by means of a location update reply message (M116) .
• the CSCF then completes the application layer registration and the normal location update (step S24) by transmitting the resource confirmation RCF message M117 to the user equipment of the subscriber 1 in order to acknowledge the registration.
• the buffering means for storing the subscriber data (2G profile) from the 2G registration element in the roaming element is arranged to store the data only for a predetermined period of time.
• the application layer registration (the normal location update) in the 3G network is not detected by said roaming element 9 within this period of time, the subscriber data are cleared.
• the roaming element 9 detects the normal location update in the 3G network after the subscriber data buffered are cleared, it is possible to request the respective subscriber data again from the 2G registration element 4. This can be executed for example by re-sending the location update message (step S ⁇ ; M105) or by sending a specific message (not shown) for merely requesting this information.
• the period of time can be set to be short. Hence, only a small storage capacity for the buffering means is required, even if several subscriber roaming procedures are to be handled by the roaming element 9 concurrently.
• the normal location update is started by the roaming element 9 in any case immediately after the transport layer location update (steps S3, S4) request is responded by the registration element 4 of the
• the roaming element 9 initiates a normal location update in the 2G network and buffers the subscriber data sent by the registration element 4.
• the following steps may correspond to the steps S20 to S24. Since the signaling procedure of this embodiment is equivalent in both cases (the case the GPRS subscription is present and the case that no GPRS subscription is present in the HLR) , the roaming functionality as a whole is simplified.
• the present invention is also applicable in the case that a location update is tried as a first registration and a transport layer access is tried as a second registration.
• a location update procedure or a transport layer access for example with different parameters/subscriber data or the like
• the order of the respective substeps (S2 to S7) is then to be adapted accordingly (changing of the order and/or repeating of substeps) .
• One advantage of the roaming procedure according to the present invention are first that the signaling load is significantly reduced in specific error cases. Namely, according to the conventional procedure, the transport layer registration is first completed before a normal location update in the application layer registration (and hence e.g. a check of the allowance for roaming of the subscriber 1) is executed. Furthermore, the usage of services only requiring a transport layer registration by invalid subscribers can be prevented.
• the present invention can be used also for other communication types, not only for the above described packed switched and/or circuit switched modes.
• the present invention proposes a method of performing roaming of a subscriber 1 using a first transmission type from a first network 2 to a second network 5 being based on a second transmission type, said method comprising a first registering step S4 for registering said subscriber 1 in said second network 5 on the basis of one of said first and said second transmission types, and in the case that said first registering step fails, a second registering step S7 for registering said subscriber 1 in said second network 5 on the basis of the other of said first and said second transmission types.
• the present invention proposes also a corresponding device.

Applications Claiming Priority (1)

Publications (1)

Family

ID=8164103

Family Applications (1)

Country Status (3)

Families Citing this family (8)

Family Cites Families (1)

• 2000
  • 2000-09-22 EP EP00960688A patent/EP1319317A1/de not_active Withdrawn
  • 2000-09-22 WO PCT/EP2000/009307 patent/WO2002025981A1/en not_active Application Discontinuation
  • 2000-09-22 AU AU2000272891A patent/AU2000272891A1/en not_active Abandoned

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events