WO2011022873A1

WO2011022873A1 - Technique for routing a signal in a communication network

Info

Publication number: WO2011022873A1
Application number: PCT/CN2009/073483
Authority: WO
Inventors: Jie Lin; Lin Zhou
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2009-08-25
Filing date: 2009-08-25
Publication date: 2011-03-03

Abstract

The invention relates to a technique for routing a signal from a mobile terminal in a communication network. A method aspect of the technique comprises receiving an identification signal from the mobile terminal (209, 211), extracting an International 5 Mobile Subscriber Identity (IMSI) associated with the mobile terminal from the identification signal, and routing the signal upon the basis of the IMSI in the communication network.

Description

TECHNIQUE FOR ROUTING A SIGNAL IN A COMMUNICATION NETWORK

FIELD OF INVENTION

[0001] The present invention relates to mobile communications networks, and more particularly to multi-operator mobile networks.

BACKGROUND OF THE INVENTION

[0002] Building, expanding and upgrading radio communication systems, such as 2nd generation systems, e.g. Global System for Mobile Communications (GSM) systems or 3rd Generation Partnership Project (3GPP) systems, e.g. Universal Mobile Telecommunications System (UMTS) or Long Term Evolution (LTE) systems, involves enormous costs when good coverage should be achieved. This is due to the fact that, in order to achieve sufficient coverage over the whole geographical area intended for being covered by the radio communication system, a large number of base stations have to be provided, which is expensive.

[0003] For example, a system operator normally has to provide sufficient coverage over the whole geographical area of a country, in which the system operator provides its services due to regulations and/or in order to be commercially successful. However, in those regions of the geographical area in which there is relatively low activity in the radio communication system, offering adequate coverage by building a full Radio Access Network (RAN) completely covering these regions may not be profitable.

[0004] Besides the fact that in a traditional radio communication system, each communication system operator has to make extensive investments in order to provide sufficient coverage for its customers, also, when new technologies are rolled out, each system operator has to upgrade its RAN accordingly, which is again costly. The upcoming re-farming of the 900 MHz (Megahertz)/ 1800 MHz frequency bands currently reserved for GSM, UMTS and LTE (Long Term Evolution) technologies will lead to a considerable amount of additional capital expenditures (CAPEX) to be spent by the operators. Furthermore, operating expenditures (OPEX) will tend to increase when multiple networks, e.g. GSM, UMTS or LTE networks, are to be maintained in parallel. New site acquisitions will also be required and are also associated with increasing difficulties due to public objections, which further increases costs.

[0005] For the above reasons, there is a trend that operators of communication systems share communication networks resources. In cases where operators are allowed to pool their spectrums together, the multi-operator core network (MOCN) approach promises to be more efficient in utilizing radio resources including spectrum and to be simpler from an operation perspective. The known MOCN RAN sharing approaches are based on broadcasting multiple PLMN IDs (PLMN: Public Land Mobile Network; ID: Identification) within a single cell of a communication network. In order to register with the single cell, a user entity (UE) representing a mobile terminal selects one particular of the multiple PLMN IDs to register with it. In addition, in the cases of handover (HO), the PLMN ID may also be used for filtering the cell neighbour list.

[0006] The known MOCN sharing solutions are largely based on broadcasting multiple PLMN IDs across a single cell of a communication network, which is suitable for mobile terminals conforming to a later (post release 5) 3GPP standard release. In particular, according to the known MOCN sharing approaches, the network selection decision is made by the mobile terminal and not by the operators on the network side.

SUMMARY OF THE INVENTION

[0007] A goal to be achieved by the present invention is allowing operators to have more control over how signals from mobile terminals are routed in a communication network in order to, for example, ensure fairness between e.g. two different mobile network operators (MNO) sharing the same Radio Access Network (RAN) resources.

[0008] According to a first aspect, a method for routing a signal from a mobile terminal in a communication network is provided. The method comprises receiving an identification signal from the mobile terminal, extracting an international mobile subscriber identity (IMSI) associated with the mobile terminal from the identification signal, and routing the signal upon the basis of the IMSI in the communication network. The identification signal may be transmitted by the mobile terminal to a network node, e.g. to a base station being configured to perform the method for routing the signal. In order to extract the IMSI, the received identification signal may e.g. be processed in order to analyze the same.

[0009] According to an implementation form, the signal may be routed to a certain communication network, for example to a certain core network associated with a certain operator which is indicated by the IMSI comprising information relating to an agreement with the networks operator. For example, the signal may be routed to the certain communication network, e.g. to a certain network cell or a core network, if the IMSI indeed indicates the same.

[0010] According to an implementation form, the method may comprise determining an identifier, e.g. a tag identifier or a network identifier, upon the basis of the IMSI, wherein the identifier indicates a certain communication network, for example a certain core network associated with a certain operator, and routing the signal upon the basis of the identifier to the certain communication network. The identifier may also be transmitted to a network node, for example to a base station being configured to route the signal to the network or to a certain cell indicated by the identifier.

[0011] According to an implementation form, the IMSI may indicate a roaming agreement with a first communication network associated with a first operator and with a second communication network associated with a second operator. Thus, the method may comprise randomly selecting either the first or the second communication network, and routing the signal to the randomly selected first or second communication network. The random selection process may be implemented using a randomly selected number, wherein a value of the randomly selected number indicates either the first or the second operator or network.

[0012] According to an implementation form, the IMSI may indicate a roaming agreement with a first communication network associated with a first operator, and with a second communication network associated with a second operator. The method may comprise randomly selecting either the first or the second communication network, determining an identifier, for example a tag identifier or a network identifier, upon the basis of the IMSI, wherein the identifier indicates the randomly selected communication network, and routing the signal upon the basis of the identifier to the randomly selected communication network. The random selection and the handling of the identifier may be performed as mentioned above. -A- [0013] According to an implementation form, the method may comprise determining an identifier, for example a tag identifier or a network identifier, upon the basis of the IMSI, wherein the identifier indicates a certain communication network, in particular a certain core network associated with a certain operator. The method may further comprise transmitting the identifier to a network entity, in particular to an eNodeB base station. Upon receiving the identifier, a filter may be created which reflects the association of the mobile terminal with the certain communication network. Furthermore, the method may comprise applying the filter to a cell neighbour list for handover purposes.

[0014] According to an implementation form, the method may comprise transmitting the identification signal by the mobile terminal upon switching on or moving into a new cell of the communication network. Thus, the identification signal may only be transmitting if further routing or handover or registration is necessary.

[0015] According to an implementation form, an identity request message may be transmitted to the mobile terminal, if the identification signal does not comprise the IMSI. The identity request message may indicate a transmission or a re-transmission of another or the identification signal comprising the IMSI in order to obtain the relevant IMSI information. Thus, the IMSI may be requested if missing.

[0016] According to an implementation form, the identification signal may be received or transmitted via a Non Access Stratum (NAS) signalling message, which is a standardised message used for communication control/signalling between a mobile terminal or user entity (UE) and the core networks.

[0017] According to an implementation form, the signalling message may be associated with a call. Thus, the communication network may be a telephony communication network.

[0018] According to an implementation form, the communication network may belong to at least one of the following communication network technologies: Universal Mobile Telecommunication System (UMTS), Global System for Mobile Communications (GSM), Long Term Evolution (LTE), and Code Division Multiple Access 2000 (CDMA 2000).

[0019] According to an implementation form, the method may further comprise registering the mobile terminal in the communication network upon the basis of the IMSI.

[0020] According to another aspect, the invention relates to a network entity, for example to a base station or to a radio network controller, being configured, in particular programmably configured, to carry out the inventive method for routing a signal from a mobile terminal in a communication network. The network entity may comprise programmable means respectively arranged to carry out the steps of the inventive method.

[0021] According to another aspect, a computer program is proposed comprising program code for executing the method for routing a signal from a mobile terminal in a communication network when run on a computer. According to a still further aspect, a computer readable recording medium is proposed having stored such computer program thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Below, embodiments of the invention will be described with respect to the following figures, in which:

[0023] Fig. 1 shows an embodiment of a method for routing a signal from a mobile terminal in a communication network;

[0024] Fig. 2 shows a first embodiment of a communication network;

[0025] Fig. 3 shows a second embodiment of a communication network; and

[0026] Fig. 4 shows a handover diagram.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] As shown in Fig. 1, the method comprises the step of receiving 101 an identification signal from the mobile terminal, the step of extracting 103 an international mobile subscriber identity (IMSI) associated with the mobile terminal from the identification signal, and the step of routing 105 the signal upon the basis of the IMSI in the communication network.

[0028] Preferably, the IMSI or the NRI (Network Readiness Index) are acquired at a base station (BSC) or at a radio network controller (RNC), or at an MME of the mobile terminal carrier preferably over Non Access Stratum (NAS) messages. Using such information, the BSC or RNC or MME can route the signal, e.g. a call, to an appropriate core network.

[0029] In cases where the mobile terminal acting as a roamer has a roaming agreement with multiple operators, the BSC or RNC or MME may draw a random selection along the applicable operators and decide which operators core network the signal should be routed to.

The random selection may follow a pre-specified ratio which may be configurable from an operation and maintenance centre (OMC).

[0030] According to an implementation form based on LTE communication technology, a handover (HO) may be controlled by a base station, e.g. by an eNodeB, so that the core network selection decision made at, e.g., the MME will be passed, for example in the form of a network identification or tag, onto the eNodeB so that the same may filter the cell neighbour list for that mobile terminal accordingly.

[0031] In order to register and route in the communication network, a single PLMN ID or MNC (MNC: Mobile Network Code) representing a shared NRI may be broadcast in the SIB, by way of example.

[0032] In case of a GSM or UMTS MOCN scenario, upon switch on or first move into a new cell, the mobile terminal may send a location update to the core network via a NAS message. The NAS message may contain either the IMSI or a TMSI (Temporary Mobile Subscriber Identity). If the IMSI is not available from the above message, the BSC or RNC may construct an identity request message and send it to the mobile terminal, wherein the BSC / RNC pretends to belong to the core network. Upon receiving this message, the mobile terminal may reply with its IMSI. After obtaining the IMSI, the BSC or RNC may route the call according to the rules exemplarily described in the following:

[0033] If the mobile terminal is not a roamer or if it is a roamer having only a roaming agreement with a single operator, then the signal, which may be a call, may be routed to the operator's core network indicated by the IMSI. However, if the mobile terminal is a roamer having a roaming agreement with multiple operators, then the BSC or RNC may draw a random selection and route the call accordingly. The random selection preferably follows a pre-specified ratio which may be configurable from the OMC.

[0034] In the case of LTE MOCN applications, upon switch on or first move into a new cell, the mobile terminal may send a location update to the core network via a NAS message. The message may contain either the IMSI or the TMSI. If the IMSI is not available from the above message, the MME may construct an identity request message and send it to the mobile terminal requesting for the IMSI. Upon receiving this message, the mobile terminal may reply with its IMSI. After analyzing the IMSI, the MME may, if the mobile terminal is not a roamer or if it is a roamer but only has a roaming agreement with a single operator, create a core network identifier or tag uniquely associated with the core network that the mobile terminal belongs to. However, if the mobile terminal is a roamer which has a roaming agreement with multiple operators, then the MME may draw a random selection and create a core network identifier or tag that corresponds to the outcome of the random selection. The random selection may follow a pre-specified ratio which may be configurable from the OMC.

[0035] Then, the MME may send the core network identification or tag down to a network entity, e.g. to an eNodeB, in the form of a standard message, e.g. in the form of an IE (Information Element) of a standard message. Upon receiving the core network identification or target, the eNodeB may route the call accordingly.

[0036] Fig. 2 shows, by way of example, a communication network employing the principles of the present invention. The communication network comprises a first communication network 201, e.g. a core network (CN) associated with a first operator, and a second communication network 203, e.g. a further core network associated with a second operator. Further, a shared base station (BSS) is present which communicates with the networks 201 and 203. The BSS comprises a BSC 205 which communicates, e.g. via a network entity 207 comprising e.g. a BTS, with mobile terminals 209 and 211 (UE) communicating e.g. via different networks.

[0037] The UEs 209 and 211 from both operators may e.g. decode the MNC (Mobile Network Code) in the SIB (System Information Broadcast) and respond to the respective CN 201, 203, with initial registration or cell update via a direct transfer message. An, e.g., 15 digit IMSI, which may be embedded in the direct transfer messages from the UE, may be decoded by the BSC 205, wherein, once registered, the UEs 209, 211, may indicate, e.g. display, information, e.g. a logo, indicating an association with a certain operator. The BSC 205 has access to an association between IMSI series or NRI with individual operators. Upon receiving the direct transfer messages from the respective UE 209, 211, the BSC 205 will decode the IMSI or the TMSI or a P-TMSI, and route the call to the appropriate CN 201, 203, based on the IMSI or NRI which corresponds to an operator. For calls where neither IMSI nor TMSI is available, the BSC 205 may route them to randomly selected core networks.

[0038] Fig. 3 shows another communication network comprising a first communication network 301, e.g. a CN, associated with a first operator, and a second communication network 303, e.g. a CN, associated with a second operator. Furthermore, a shared BSS 305 (Base Station Subsystem) comprising a BSC 307 and a BTS 309 communicating with mobile terminals, e.g. user entities (UEs, not shown), is present, wherein the BSC 307 may communicate with a shared OSS (Operational Support Services) entity 311, e.g. comprising an NMS entity 313 (NMS: Network Management Software) and an EMS entity 315 (EMS: Element Management System) communicating e.g. with a display device 317.

[0039] The communication network showed in Fig. 3 may be associated e.g. with a GSM pseudo MOCN network architecture which is identical to that of proper MOCN (post release 5). According to an implementation, instead of broadcasting multiple PLMN Ids in the System Information Broadcast (SIB) and routing the calls based on UEs selection of a PLMN Id, the pseudo MOCN may only use one PLMN Id in the SIB and the call is routed to its destination CN 301, 303 based on the IMSI used by the UE.

[0040] The inventive approach may also be employed for managing handovers. In particular in GSM or UMTS MOCN scenarios, upon obtaining the IMSI, the BSC or RNC may create a filter for the respective mobile terminal, the filter reflecting the association of the mobile terminal and its home operator as well as a roaming agreement. The BSC or RNC may apply this filter to a cell neighbour list whenever a handover operation needs to be carried out with that mobile terminal. Preferably, the handover algorithms remain unchanged.

[0041] In an LTE MOCN environment, upon receiving the core network identification or tag, a network entity may create a filter for this mobile terminal, the filter reflecting the association of the mobile terminal and its core network identification or tag. The network entity, for example an eNodeB, may apply this filter to the cell neighbour list whenever a handover operation needs to be carried out with that mobile terminal. Preferably, the handover algorithms remain unchanged.

[0042] According to some implementations, every cell in a neighbour list of a given cell will be associated with a unique network ownership, e.g. operator. A BSC may further associate an IMSI series or NRI with a subset of the neighbours list. This subset of the neighbours list may then be sent down to a respective UE associated with the IMSI series for taking measurements. In cases where no operator specific information is available for the UE, the BSC may regard all neighbour cells in the list valid for that UE. A handover control mechanism remains unchanged but the neighbour cell list for a given UE will be used to determine which neighbour cell or network the UE can be handed over to. The BSC may try to determine whether it is possible to HO a call within a certain network first using e.g. the same technology and different frequency bands or the same bands and different technology. If this is not possible, a roam out may then be attempted.

[0043] Fig. 4 illustrates an IMSI based handover in a communication network including a shared BSS comprising a BSC 401 and a BTS 403 associated, e.g., with a certain operator. Furthermore, mobile terminals 404 and 405 (UEs) associated with e.g. different operators are present. The communication network further comprises network cells 407, 409 and 411 associated with, e.g., different dedicated operators.

[0044] The BSC 401 may indicate 413 neighbouring cells associated with a first operator, wherein a measurement and reporting 415 of the respective first operator's dedicated and shared neighbouring cells may be performed. Furthermore, the BSC 401 may indicate 417 neighbouring cells associated with a second operator, wherein a measurement and reporting 419 of the respective second operator's dedicated and shared neighbouring cells may be performed. In certain cases, a handover 421 to network cell 407 associated with the first operator may not be possible, as shown in Fig. 1. In other cases, a handover to network cell 411 dedicated to e.g. the second operator, may be performed.

[0045] According to some implementations, the inventive approach may be employed in 3GPP standard release environments, in UMTS environments and in GSM environments, wherein a configurable distribution of roamers among network sharing operators may be achieved.

[0046] According to some implementations, an IMSI based NAS routing, a NAS call routing and a handover for MOCN sharing with e.g. GSM, UMTS and LTE technologies are enabled.

[0047] According to some further implementations, an IMSI based NAS call routing and handover approach is provided that is transparent to the core network. According to some implementations, a network entity, e.g. a BSC or RNC or MME may obtain the IMSI by sending an identity request, wherein the BSC / RNC / MME pretends to belong to the core network.

[0048] According to some further implementations, a ratio configurable random selection approach may be used to determine which operator's core network to register when the mobile terminal has a roaming agreement with multiple operators core networks.

[0049] According to some further implementations, a core network identifier or tag may be created to associate with the IMSI for an LTE MOCN environment, by way of example.

[0050] According to some further implementations, a mobile terminal specific core network identification filter may be used for handover operations.

Claims

CLAIMS What is claimed is:

1. A method for routing a signal from a mobile terminal in a communication network, the method comprising:

receiving (101) an identification signal from the mobile terminal;

extracting (103) an International Mobile Subscriber Identity (IMSI) associated with the mobile terminal from the identification signal; and

routing (105) the signal upon the basis of the IMSI in the communication network.

2. The method according to claim 1, further comprising routing the signal to a certain communication network, in particular to a certain core network associated with a certain operator, indicated by the IMSI.

3. The method according to any one of the preceding claims, comprising:

determining an identifier, in particular a tag identifier or a network identifier, upon the basis of the IMSI, the identifier indicating a certain communication network, in particular a certain core network associated with a certain operator; and

routing the signal upon the basis of the identifier to the certain communication network.

4. The method according to any one of the preceding claims, wherein the IMSI indicates a roaming agreement with a first communication network associated with a first operator and a second communication network associated with a second operator, the method comprising randomly selecting either the first or the second communication network and routing the signal to the randomly selected communication network.

5. The method according to any one of the preceding claims, wherein the IMSI indicates a roaming agreement with a first communication network associated with a first operator and a second communication network associated with a second operator, the method comprising:

randomly selecting either the first or the second communication network; determining an identifier, in particular a tag identifier or a network identifier, upon the basis of the IMSI, the identifier indicating the randomly selected communication network; and

routing the signal upon the basis of the identifier to the randomly selected communication network.

6. The method according to any one of the preceding claims, comprising:

determining an identifier, in particular a tag identifier or a network identifier, upon the basis of the IMSI, the identifier indicating a certain communication network, in particular a certain core network associated with a certain operator;

transmitting the identifier to a base station, in particular to an eNodeB base station;

upon receiving the identifier, creating a filter reflecting the association of the mobile terminal with the certain communication network; and

applying the filter to a cell neighbor list for handover purposes.

7. The method according to any one of the preceding claims, comprising transmitting the identification signal by the mobile terminal upon switching on or moving into a new cell of the communication network.

8. The method according to any one of the preceding claims, comprising:

transmitting an identity request message to the mobile terminal if the identification signal does not comprise the IMSI, the identity request message indicating a transmission of another identification signal comprising the IMSI.

9. The method according to any one of the preceding claims, wherein the identification signal is received or transmitted via a Non Access Stratum signal.

10. The method according to any one of the preceding claims, wherein the signal is a call or a call signal.

11. The method according to any one of the preceding claims, wherein the communication network employs at least one of the following communication network technologies:

Universal Mobile Telecommunication System (UMTS);

Global System for Mobile Communications (GSM);

Long Term Evolution (LTE); and

Code Division Multiple Access 2000 (CDMA2000).

12. The method according to any one of the preceding claims, further comprising registering the mobile terminal in the communication network upon the basis of the IMSI.

13. A network entity, in particular a base station or a radio network controller, being configured, in particular programmably configured, to carry out the method for routing a signal according to anyone of the claims 1 to 12.

14. Computer program comprising program code for executing the method according to any one of the claims 1 to 12 when run on a computer.