Wireless access network node, user equipment, and method

Abstract

A radio access network node and method are provided in which a default mobility management entity (MME) receives a request from a base station (eNB) to set up a communication connection to a mobile device (UE) having an associated usage type. In response to the request from the UE 3D, the default MME 9A sends a message to the eNB 5 identifying the dedicated MME 9D to which the UE should be rerouted (S610). The dedicated MME has a supported service type corresponding to the usage type associated with the UE. The eNB sends a response to the default MME (S612). The response indicates whether the rerouting to the dedicated MME was successful or unsuccessful (e.g., due to overload of the dedicated MME). If the rerouting was unsuccessful, the default MME attempts to serve the UE instead of the dedicated MME (S614).

Description

Technical Field

[0001] The present invention relates to a communication system. In particular, but not limited to, the present invention relates to a wireless communication system and its devices operating according to the Third Generation Partnership Project (3GPP) standards or their equivalents or derivatives, including Universal Terrestrial Radio Access Network (UTRAN), and Long Term Evolution (LTE) of UTRAN (E-UTRAN), including LTE-Advanced, etc. The present invention relates in particular, but not limited to, the use of a dedicated core network.

Background Art

[0002] Under the 3GPP standards, a "NodeB" (or "eNB" in LTE) is a base station through which a plurality of mobile devices connect to a core network and communicate with other mobile devices or a plurality of remote servers. For this to be possible, a plurality of mobile devices establish a so-called Radio Resource Control (RRC) connection with the serving base station. For simplicity, this application uses the term base station to refer to any such plurality of base stations. The plurality of communication devices may be, for example, a plurality of mobile phones, a plurality of smartphones, user equipment, a plurality of personal digital assistants, a plurality of laptop computers, a plurality of web browsers, and other mobile communication devices. The 3GPP standards also make it possible to connect non-mobile user equipment, such as a plurality of Wi-Fi routers, a plurality of modems, etc., which can be implemented (generally) as part of stationary equipment, to the network. For simplicity, this application refers in the specification to a plurality of mobile communication devices (or a plurality of mobile devices), but it will be understood that the described technology can be implemented in any mobile device and "non-mobile" device that can connect to such a core network.

[0003] Under the 3GPP specifications, multiple base stations are connected to a core network (referred to as an evolved packet core (EPC) network in LTE). To track multiple mobile devices and facilitate handovers between different base stations, the core network consists of multiple mobility management entities (MMEs) that communicate with the multiple base stations connected to the core network. Communication between the multiple mobile devices and their associated MMEs is performed using non-access stratum (NAS) signaling (via the serving base station). In some core networks, depending on the radio access technology (RAT) used by the mobile device, a serving GPRS support node (SGSN) may be used instead of an MME.

[0004] The latest development results of the 3GPP specifications are referred to as the long term evolution (LTE) of the EPC network and the E-UTRA (Evolved UMTS Terrestrial Radio Access) network. LTE (and more recently LTE-Advanced, i.e., "LTE-A") enables user equipment (UE) such as multiple mobile devices to efficiently connect to the core network using multiple dedicated core network nodes (multiple dedicated MMEs, etc.). Details of the features of this so-called "dedicated core network" (DECOR) are discussed in 3GPP Technical Report (TR) 23.707 (V13.0.0) and 3GPP document S2-152107. This latter 3GPP document is related to version 13.2.0 of 3GPP Technical Specification (TS) 23.401.

[0005] In summary, the DECOR feature enables a network operator to deploy multiple dedicated core networks (DCNs) within its network (along a common (i.e., non-dedicated) core network). Each DCN may be dedicated to serving a particular type(s) of subscriber and / or a particular type(s) of service. The multiple DCNs are optional and may be selectively deployed for various types of radio access technologies (RATs) such as GERAN (GSM (registered trademark) EDGE Radio Access Network), UTRAN, and / or E-UTRAN. For example, a network operator may deploy multiple dedicated MMEs (to support E-UTRAN) and not deploy multiple dedicated SGSNs (and thus not support GERAN / UTRAN), or vice versa. The motivation for deploying DECOR may include, among other things, providing multiple DCNs with specific multiple characteristics / multiple functions or scaling, and isolating specific multiple UEs or multiple subscribers (e.g., multiple machine-to-machine (M2M) subscribers, multiple subscribers belonging to a particular enterprise or distinct administrative domain, multiple subscribers belonging to a mobile virtual network operator (MVNO), etc.) from other multiple UEs or multiple subscribers, etc.

[0006] On the other hand, such different groups of customers and devices may have different requirements in terms of multiple characteristics, multiple traffic characteristics, availability, congestion management, signaling, and user plane data usage, etc. Multiple DCNs, including multiple dedicated / special core network elements / resources, can help multiple operators meet the requirements of such device / customer groups. The multiple DCNs may also contribute to meeting network availability and / or redundancy requirements, and facilitate independent scaling or special function provisioning for a particular user or traffic type, as well as separation of different types of users and traffic from each other.

[0007] Each DCN consists of one or more MME / SGSNs and may optionally consist of one or more Serving Gateways (S-GWs), Packet Data Network (PDN) Gateways (P-GWs) and / or Policy and Charging Rules Functions (PCRFs). Each subscriber can be assigned to a DCN and served by this DCN based on their respective subscription information ("UE usage type"). Multiple networks with multiple DCNs can have a default DCN (or default core network node of the common core network) for managing multiple UEs for which the DCN is not available and / or a default DCN for managing multiple UEs when sufficient information (e.g., associated UE usage type) for assigning the UE to a specific DCN is not available. One or more DCNs sharing the same RAN may be arranged together with a default DCN (or default core network node).

[0008] There is one UE usage type per subscriber that does not require specific UE capabilities. That is, this UE also functions with UEs compliant with previous standard releases. Similarly, in the case of multiple legacy MMEs, it is possible to move the UE context from one (source) MME / SGSN to another (target) MME / SGSN, for example, during handover, load balancing, initial network attachment, etc. When an MME / SGSN supporting multiple DCNs selects a target MME / SGSN for a UE, the selection of this target MME / SGSN is restricted to the same DCN (due to the UE usage type).

[0009] 3GPP Work Item (WI) document RP-151048 discusses the signaling support for the so-called NAS Node Selection Function (NNSF) and the MME / SGSN (re)selection function of DECOR. Further, S2-152107 describes the possible NAS message redirection procedure where NAS messages are redirected from a certain MME / SGSN (e.g., the default MME / SGSN) to a dedicated MME / SGSN based on the UE usage type. This may be required, for example, when a UE first attempts to connect to the core network and establishes a connection with the default MME (selected for the UE by the serving base station of the UE) in a core network that does not support the UE usage type associated with this UE. Thus, NAS message redirection is initiated by the currently selected (e.g., default) serving MME / SGSN of the UE by sending a request to the serving base station of the UE to reroute the UE's NAS message to a dedicated MME / SGSN. This request includes parameters (e.g., the identifier of the MME group) corresponding to the DCN assigned to that UE usage type. When the serving base station receives a request to reroute the UE's NAS message to a dedicated MME / SGSN, it executes the NNSF procedure to select a suitable dedicated MME / SGSN corresponding to the received parameters and transfers the NAS message (e.g., the so-called "initial UE message") to the selected dedicated MME / SGSN. Thereby, the dedicated MME / SGSN is established as the UE's new serving MME / SGSN.

[0010] Such NAS message redirection (and / or MME / SGSN reselection) may also be required for load balancing purposes (e.g., moving subscribers from an overloaded MME / SGSN or an MME / SGSN with a relatively high load to another MME(s) / SGSN(s) with a relatively low load). SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] However, the inventors recognize that the current procedures for the functions of MME / SGSN (re)selection and / or NAS message rerouting of DECOR are inefficient, and as a result, may lead to unnecessary signaling and / or creation / maintenance of UE contexts at the wrong MME / SGSN at the wrong time.

[0012] Accordingly, a preferred embodiment of the present invention aims to provide a method and apparatus for overcoming or at least partially alleviating at least some of the above problems.

Means for Solving the Problems

[0013] For the sake of efficiency of understanding by those skilled in the art, the present invention will be described in detail in the context of 3GPP systems (UMTS, LTE), but the principles of the present invention can be applied to other systems in which a plurality of mobile devices or user equipment (UE) access the system using a plurality of dedicated core network nodes.

[0014] In one aspect, the present invention provides a communication device for providing communication access to a communication network, the communication device comprising: a controller adapted to control communication of at least one communication device located within an associated communication cell via the communication device; and a transceiver operable to communicate with the at least one communication device within the associated communication cell and operable to communicate with a plurality of Mobility Management Entities (MMEs), wherein the transceiver receives signaling from a communication device having an associated usage type to establish a communication connection via the communication device, transmits the signaling to set up the communication connection to a default MME, and in response to the signaling to set up the communication connection, receives from the default MME a message identifying a dedicated MME to which the signaling to set up the communication connection should be re-routed, the dedicated MME having at least one support service type corresponding to the usage type associated with the communication device that transmitted the signaling to establish the communication connection; the controller is operable to determine whether the dedicated MME is suitable for serving the communication device that transmitted the signaling to establish the communication connection, and the transceiver is operable to transmit, based on the determination of whether the dedicated MME is suitable for serving the communication device, a response indicating one of (a) unsuccessful re-routing to the dedicated MME and (b) successful re-routing to the dedicated MME, to the default MME.

[0015] In one aspect, the present invention provides a communication device for providing communication access to a communication network, the communication device comprising: a controller adapted to control communication of at least one communication device located within an associated communication cell via the communication device; and a transceiver operable to communicate with the at least one communication device within the associated communication cell and operable to communicate with at least one Mobility Management Entity (MME), wherein the at least one MME has at least one supported service type and is dedicated to serving communication devices having a usage type corresponding to the at least one supported service type, and the transceiver is operable to receive, for each of the at least one MME, respective information identifying a group associated with the MME and respective information identifying the at least one supported service type of the MME.

[0016] In one aspect, the present invention provides a communication device comprising: a memory configured to hold information identifying a usage type associated with the communication device; a controller adapted to control communication of the communication device with a communication device operating a cell; and a transceiver operable to transmit, to the communication device, signaling for establishing a communication connection with a Mobility Management Entity (MME), the signaling comprising information identifying the usage type associated with the communication device.

[0017] In one aspect, the present invention is a Mobility Management Entity (MME) of a communication network, the MME being configured to operate as a default MME, operable to communicate with a communication device operating a communication cell and operable to communicate with at least one communication device within the communication cell, the transceiver comprising: receiving, from the communication device, signaling for setting up a communication connection to a communication device having an associated usage type; in response to the signaling for setting up the communication connection, identifying, for the communication device that transmitted the signaling for establishing the communication connection, at least one support service type corresponding to the usage type associated with the communication device, and sending, to the communication device, a message identifying the dedicated MME having the at least one support service type, the dedicated MME being a dedicated MME to which the signaling for setting up the communication connection should be re-routed; receiving, from the communication device, a response indicating one of (a) unsuccessful re-routing to the dedicated MME and (b) successful re-routing to the dedicated MME; and being operable to provide the MME.

[0018] In one aspect, the present invention is a mobility management entity (MME) of a communication network, the MME being configured to operate as a dedicated MME, operable to communicate with a communication device operating a communication cell and operable to communicate with at least one communication device within the communication cell; a transceiver; and a controller operable to obtain information identifying the at least one support service type configured to support communication devices having a usage type corresponding to at least one support service type. The transceiver is operable to transmit to the communication device information identifying a group associated with the MME and information identifying at least one service type supported by the MME, thereby providing an MME. Aspects of the present invention extend to corresponding systems, methods, and computer program products such as computer-readable storage media storing instructions operable to program a programmable processor to perform the methods as described in the aspects and possible forms shown above or described in the claims, and / or to program a computer appropriately configured to provide an apparatus as described in any of the claims of the claims.

[0019] Each feature disclosed and / or illustrated in this specification (including the claims) may be incorporated into the present invention independently of (or in combination with) any other disclosed and / or illustrated feature. Specifically, without limitation, any feature of any of the claims dependent on a particular independent claim may be incorporated into that independent claim in any combination or individually.

[0020] Here, embodiments of the present invention will be described by way of example with reference to the accompanying drawings.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

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Figure 9

Mode for Carrying Out the Invention

[0022] Overview FIG. 1 schematically shows a mobile (cellular) long-distance communication network 1 in which multiple users of multiple mobile devices 3A to 3D communicate with each other and with other multiple users via multiple E-UTRAN base stations 5A and 5B and communicate with a core network 7 using the E-UTRA radio access technology (RAT). Those skilled in the art will understand that, for the purpose of explanation, FIG. 1 shows four mobile devices 3 and two base stations 5, but it will be understood that the system will typically include other base stations and mobile devices in practice.

[0023] As is well known, when the mobile device 3 moves around within a geographical area covered by the long-distance communication network 1, it may enter and exit a plurality of areas (i.e., a plurality of radio cells) served by the base station 5. To track the progress of the mobile device 3 and facilitate movement between different base stations 5, the core network 7 includes a plurality of mobility management entities (MMEs) 9A - 9D. Among these MMEs, MMEs 9A - 9C are common MMEs (i.e., not associated with any specific UE usage type or associated with all UE usage types), and MME 9D is a dedicated MME (i.e., associated with one or more specific UE usage types). Thus, as shown, MME 9D forms part of DCN 7D, while the other MMEs 9A - 9C form part of the main (or common) core network 7. Moreover, MME 9A is configured to operate as the default MME for a plurality of mobile devices 3 (e.g., when first connecting to the core network 7 and / or when other MMEs are unavailable). Providing such a default MME in this way helps reduce the risk of service interruption.

[0024] The plurality of MMEs 9 communicate with a plurality of base stations 5 coupled to the core network 7. The core network 7 also includes an HSS 11 and one or more gateways such as a serving gateway (S-GW) 18 and / or a packet data network gateway (P-GW) 19.

[0025] A plurality of mobile devices 3 and their respective plurality of serving base stations 5 are connected via an LTE air interface, a so-called "Uu" interface. The plurality of base stations 5 are connected to each other via a so-called "X2" interface. Each base station 5 is also connected to a plurality of nodes (i.e., MME 9 and S-GW 18) of the core network 7 via a so-called "S1" interface. A connection from the core network 7 to an external IP network 20 such as the Internet is also provided via the P-GW 19. Although not shown in FIG. 1, the MME 9 is also connected to the HSS 11 and the gateways 18, 19 via their respective 3GPP interfaces.

[0026] For each mobile device 3, the HSS 11 stores relevant subscription data such as the configuration data and subscription data required for a 3GPP subscriber to access the network 1, the associated service type(s) and service preference, information identifying the corresponding subscriber group(s), etc. Specifically, the HSS 11 stores the subscription information parameter "UE usage type" that can be used in the selection of the appropriate MME 9 for each subscriber (each mobile device 3). For each supported UE usage type, the network operator configures a set (one or more) of associated MME 9s (or DCNs). However, it will be understood that, where appropriate, each MME 9 (or DCN) may be associated with two or more UE usage types, and / or the default MME 9 may be associated with a UE usage type that does not have a dedicated MME 9D and / or a dedicated core network 7D.

[0027] In this system, the subscription associated with the mobile device 3D has a UE usage type that corresponds to the UE usage type associated with the MME 9D. In other words, the MME 9D is a core network node that forms part of the dedicated core network 7D of the mobile device 3D. Thus, the core network 7 ensures that the mobile device 3D is served by this dedicated core network 7D as much as possible. To do this, the HSS 11 (or the previous MME 9 of the mobile device 3) provides the UE usage type associated with the mobile device 3 to the selected MME 9 when the mobile device 3 first attempts to establish a connection with the MME 9 (initially) selected by the base station 5.

[0028] Although not shown in FIG. 1, the dedicated MME 9D is configured to select an associated dedicated S-GW and P-GW for the mobile device 3D based on its UE usage type.

[0029] In this example, it is advantageous that the base station 5 is configured to obtain information about the supported service type(s) of each connected MME 9 from the MME 9. For example, the base station 5B obtains this information using appropriate S1 signaling (such as an "S1 setup response" message, an "MME configuration update" message, etc.) during the initial setup procedure that configures the S1 connection between the base station 5B and the MME 9D and / or at any subsequent point in time when the MME 9D is reconfigured.

[0030] Furthermore, in this example, the plurality of base stations 5 are configured to also obtain, for each mobile device 3 served by these base stations, information about each UE usage type associated with that particular mobile device 3. Advantageously, in this example, base station 5B is configured to obtain this information directly from mobile device 3 (e.g., before performing any NNSF procedure for that particular mobile device 3), or from the MME 9A that is currently serving (or was initially selected to serve) that particular mobile device 3 (e.g., from the "UE usage type" information element in a "Reroute NAS message request" message, "Downlink NAS transport" message, etc.). When base station 5B obtains the UE usage type associated with mobile device 3D directly from that mobile device 3D, this UE usage type may be obtained using implicit signaling (e.g., by determining which random access preamble is being used by mobile device 3D), or may be obtained using explicit signaling (e.g., using a low access priority indication procedure, etc.).

[0031] In this example, the base station 5 is also configured to obtain and store information about the availability of each connected MME 9 (e.g., information identifying that a particular MME is overloaded and / or information identifying the relative load for each MME). This availability information for each MME 9 is typically obtained and stored in association with information about any particular supported service type(s) of that MME 9 (i.e., multiple UE usage types). Thus, using information about the UE usage type, information about the MME support service type, and information about the availability of each connected MME 9 (if any), the base station 5B can select an appropriate dedicated MME (MME 9D in this example if available) for the mobile device 3D without using unnecessary signaling. On the other hand, when a particular MME 9 is not available, for example, due to overload, etc., even if the UE usage type of the mobile device 3D may be different from the supported UE usage type(s) associated with the selected MME 9A or 9C, the base station 5B can select the default MME 9A (or an appropriate common MME 9C) and register the mobile device 3D. To do this, the base station 5B also includes in its message to the MME 9A or 9C indication information that the associated dedicated MME 9D is (temporarily) overloaded / otherwise unavailable.

[0032] It is advantageous that the base station 5B can respond to the requesting MME 9A or 9C that the dedicated MME 9D is still unavailable (e.g., due to overload), even when the currently selected MME 9A or 9C attempts to re-route NAS messages from the mobile device 3D to the corresponding dedicated MME 9D. In this case, this indication information provided by the base station 5B prevents the requesting MME 9A or 9C from deleting any UE context held for the mobile device 3D, even if the mobile device 3D is currently registered with an inappropriate (i.e., non-dedicated) MME 9, thereby ensuring service continuity.

[0033] To facilitate sending such a response to the MME 9 that requests rerouting of the NAS message, the MME 9 that makes the rerouting request is advantageously adapted to use a message that requests a response (e.g., a so-called "class 1" message in LTE) rather than a message that is automatically considered successful when sent (e.g., a so-called "class 2" message in LTE). Such a message that requests a response may require a response (e.g., positive response indication information or negative response indication information indicating success or failure as appropriate), regardless of whether the rerouting to another MME 9 was successful. On the other hand, such a message that requests a response may be a message that requires "success" indication information indicating success and assumes failure after a predetermined time period has elapsed, or may be a message that requires "failure" indication information indicating failure and assumes success after a predetermined time period has elapsed.

[0034] In summary, it is advantageous that a plurality of base stations in this system can notify a plurality of MMEs that the dedicated MME is overloaded (or otherwise unavailable). For example, when the serving base station indicates to the default MME that the dedicated MME is overloaded, this default MME may attempt to serve the mobile device (rather than rejecting the mobile device) regardless of the associated UE usage type. Moreover, any intermediate (e.g., default) MME initially selected by the base station is configured to hold the associated UE context until it is ensured that the dedicated MME of the mobile device is available when attempting to reroute the NAS message of the mobile device (even if the associated UE context is not appropriate for the UE usage type associated with the mobile device), which is advantageous.

[0035] Mobile device FIG. 2 is a block diagram showing a plurality of major components of one of the plurality of mobile devices 3 shown in FIG. 1. As shown, the mobile device 3 has a transceiver circuit 31 operable to transmit and receive signals to and from the base station 5 via one or more antennas 33. The mobile device 3 has a controller 37 that controls the operation of the mobile device 3. The controller 37 is associated with a memory 39 and coupled to the transceiver circuit 31. Although not necessarily shown in FIG. 2, the mobile device 3 of course has all the normal functions (such as the user interface 35, etc.) of a conventional mobile device 3, which may be provided by any one or any combination of hardware, software, and firmware as appropriate. The software may be pre-installed in the memory 39 and / or downloaded, for example, via a long-distance communication network or from a removable data storage device (RMD).

[0036] In this example, the controller 37 controls the overall operation of the mobile device 3 by program instructions or software instructions stored in the memory 39. As shown, these software instructions include, among others, an operating system 41, a communication control module 43, an RRC module 44, a NAS module 45, and a usage type association module 49.

[0037] The communication control module 43 controls the communication between the mobile device 3 and the base station 5. The communication control module 43 also controls separate flows of control data transmitted to the base station 5 and (via the base station 5) other nodes such as the MME 9 and / or the S-GW 18, etc., and user data (for uplink and downlink).

[0038] The RRC module 44 is operable to generate, transmit, and receive a plurality of signaling messages formatted according to the RRC standard. For example, such a plurality of messages are exchanged between the mobile device 3 and its serving base station 5. The plurality of RRC messages may consist of, for example, a plurality of messages related to a random access procedure and / or control data (e.g., NAS messages) relayed by the serving base station 5 to the MME 9.

[0039] The NAS module 45 is operable to generate, transmit, and receive a plurality of signaling messages formatted according to the NAS protocol. For example, such a plurality of messages are exchanged between the mobile device 3 and the plurality of MMEs 9 (via the plurality of base stations 5). The plurality of NAS messages may include, for example, a plurality of NAS messages consisting of control data for registering the mobile device 3 with the MME 9.

[0040] The usage type association module 49 stores information about the usage type associated with this mobile device 3. For example, this usage type may be stored in the form of a "UE usage type" parameter. Based on this stored usage type information, the usage type association module 49 assists the RRC module 44 in selecting an appropriate preamble to initiate a random access procedure with the base station 5.

[0041] Base station FIG. 3 is a block diagram showing a plurality of main components of one of the plurality of base stations 5 shown in FIG. 1. As shown, the base station 5 includes a transceiver circuit 51 for transmitting and receiving signals to and from the mobile device 3 via one or more antennas 53, a base station interface (X2) 54 for transmitting and receiving signals to and from other base stations, and a core network interface (S1) 55 for transmitting and receiving signals to and from a plurality of core network entities (e.g., MME 9 and S-GW 18). The base station 5 has a controller 57 for controlling the operation of the base station 5. The controller 57 is associated with a memory 59. Although not necessarily shown in FIG. 3, the base station 5 of course has all the normal functions of a cellular telephone network base station, which may be provided by any one or any combination of hardware, software, and firmware, as appropriate. The software may be pre-installed in the memory 59 and / or downloaded, for example, via the communication network 1 or from a removable data storage device (RMD). The controller 57 is configured to control the overall operation of the base station 5 by program instructions or software instructions stored in the memory 59 in this example. As shown, these software instructions include, among others, an operating system 61, a communication control module 63, an RRC module 65, an S1AP module 67, and an MME availability information storage module 69.

[0042] The communication control module 63 controls the communication between the base station 5, the plurality of mobile devices 3, and other network entities (e.g., MME 9) connected to the base station 5. The communication control module 63 also controls separate flows of uplink / downlink user traffic and control data to be transmitted to the mobile device 3 associated with the base station 5, including control data for re-routing a plurality of NAS messages, for example.

[0043] The RRC module 65 is operable to generate, transmit, and receive a plurality of signaling messages formatted according to the RRC standard. For example, such a plurality of messages are exchanged between the base station 5 and a plurality of mobile devices 3 associated with the base station 5. The plurality of RRC messages may include, for example, an RRC message consisting of control data (e.g., a plurality of NAS messages) for relaying between the mobile device 3 and its serving MME 9.

[0044] The S1AP module 67 is operable to generate, transmit, and receive a plurality of signaling messages formatted according to the S1 application protocol (S1AP) standard. For example, such a plurality of messages are exchanged between the base station 5 and a plurality of MMEs 9 connected to the base station 5. The plurality of S1AP messages may include, for example, a plurality of messages related to the rerouting of NAS signaling, such as a plurality of Reroute NAS message requests, a plurality of Downlink NAS transport messages, a plurality of S1 setup messages, and associated plurality of responses.

[0045] The MME availability information storage module 69 stores information about the availability of a plurality of specific MMEs (or a plurality of MME groups) and any associated usage types. The MME availability information storage module 69 provides this information to a plurality of other modules, such as the S1AP module 67 used to reroute NAS messages.

[0046] Mobile management device Figure 4 is a block diagram showing a plurality of main components of one of the plurality of MMEs 9 shown in FIG. 1. As shown, the MME 9 includes a transceiver circuit 71, a base station interface (S1) 74 for transmitting and receiving signals to and from a plurality of base stations 5, and a core network interface 75 for transmitting and receiving signals to and from other plurality of core network nodes (such as HSS 11, etc.). The MME 9 has a controller 77 for controlling the operation of the MME 9. The controller 77 is associated with a memory 79.

[0047] Software may be pre-installed in the memory 79 and / or downloaded, for example, via the communication network 1 or from a removable data storage device (RMD). The controller 77 is configured in this example to control the overall operation of the MME 9 by program instructions or software instructions stored in the memory 79. As shown, these software instructions include, among others, an operating system 81, a communication control module 83, a non-access stratum (NAS) module 85, an S1AP module 87, and a usage type association module 89.

[0048] The communication control module 83 controls communication between the MME 9 and other plurality of network entities connected to this MME 9 (for example, the base station 5, the HSS 11, and any plurality of mobile devices 3 when connected to one of the plurality of base stations 5).

[0049] The NAS module 85 is operable to generate, transmit, and receive a plurality of signaling messages formatted according to the NAS protocol. For example, such a plurality of messages are exchanged (via the plurality of base stations 5) between the MME 9 and a plurality of mobile devices 3 associated with this MME 9. The plurality of NAS messages can include, for example, NAS messages including control data for registering the mobile device 3 with the MME 9.

[0050] The S1AP module 87 is operable to generate, transmit, and receive a plurality of signaling messages formatted according to the S1 application protocol (S1AP) standard. For example, such a plurality of messages are exchanged between the MME 9 and a plurality of base stations 5 connected to this MME 9. The plurality of S1AP messages may include, for example, a plurality of messages related to rerouting of NAS signaling, such as a plurality of NAS message rerouting requests, a plurality of downlink NAS transport messages, a plurality of S1 setup messages, and a plurality of associated responses.

[0051] The usage type association module 89 stores information about the usage type(s) associated with this MME 9. For example, the usage type may be stored in the form of a "UE usage type" parameter and / or an MME group identifier (MMEGI).

[0052] In the above description, for ease of understanding, the mobile device 3, the base station 5, and the MME 9 have been described as having a plurality of individual modules (such as a plurality of communication control modules, a plurality of RRC / NAS modules, and a plurality of S1AP modules). These modules may be provided in this way in some application forms, for example, when an existing system is modified to implement the present invention. However, in other application forms, for example, in a system designed from the beginning with the features of the present invention in mind, these modules may be incorporated into the operating system or the entire code, and these modules may not be distinguishable as separate entities in some cases. These modules may be implemented in software, hardware, firmware, or a combination thereof.

[0053] Here, a plurality of different embodiments will be described to illustrate how various aspects of the present invention can be implemented using the above-described mobile device 3, base station 5, and MME 9. The embodiments will be described with reference to the signaling (or "timing") diagrams shown in FIGS. 5 to 9.

[0054] Operation - First Embodiment FIG. 5 shows an exemplary timing diagram showing the procedure of the base station 5 for obtaining and using information about the service type of the mobile device 3 when selecting an appropriate MME 9 for the mobile device 3.

[0055] In this embodiment, the base station 5 is configured to obtain information about the supported service type(s) of the connected MME 9 during the initial setup procedure for configuring the S1 connection between the base station 5 and the MME 9.

[0056] Specifically, as shown in step S500, the base station 5 obtains this information (using its S1AP module 65) from an appropriately formatted S1 message received from the MME 9 (such as an "S1 setup response" message or an "MME configuration update" message, etc.). The contents of these messages are shown (by way of example only) in Tables 1 and 2. As can be seen, in this example, the S1 setup response of the MME 9 includes appropriately formatted information elements (IEs) including a plurality of configuration parameters associated with the MME 9. These configuration parameters consist of information for identifying the service type(s) supported by the MME 9. Each service type consists of (and / or is mapped to) a corresponding UE usage type, and thus it can be seen that the list of UE usage types of a particular MME determines which service(s) / UE usage type(s) that MME supports as a dedicated MME.

[0057] Optionally, the base station 5 may also obtain (using its own S1AP module 65) information identifying the availability of the MME 9D, e.g., whether the MME 9D is overloaded. In the example shown in FIG. 5, the base station 5 receives a properly formatted S1 message indicating that the MME 9D is overloaded.

[0058] The base station 5 is configured to add an entry for each connected MME 9 to a list of entries stored in its MME availability information storage module 69, along with appropriate indication information as to whether that MME is currently available (and, optionally, information identifying the reason why a particular MME is unavailable, e.g., not connected, overloaded, etc.). For each MME 9, the MME availability information storage module 69 also holds information identifying a plurality of any associated UE usage types (if available). Thus, upon receiving that message in step S501, the base station 5 stores (in its MME availability information storage module 69) the information that the MME 9D is unable to currently register a new plurality of mobile devices 3.

[0059] In this system, it is advantageous that the base station 5 is configured to obtain (e.g., using its RRC module 65) from each mobile device 3 served by this base station 5 information about each UE usage type / service type associated with that particular mobile device 3. This indication information may be explicit or implicit as appropriate. It is advantageous that the base station 5 is configured to obtain this information before performing any NNSF procedure for the mobile device 3 (i.e., before forwarding any NAS message from the mobile device 3 to an incorrect (or default) MME 9).

[0060] In this example, this is implicitly achieved by assigning different random access preambles (or a set of preambles) to different UE usage groups. The base station 5 is configured to notify (e.g., via system information broadcast) a plurality of mobile devices 3 within its cell of the association between each UE usage type value and the corresponding preamble in step S502.

[0061] Therefore, when the mobile device 3D has already established a radio connection with this base station 5, it can select an appropriate random access preamble (in step S504) and include it in the message regarding the random access procedure (in step S505) to notify the base station 5 of its associated UE usage type.

[0062] Therefore, by detecting which preamble is being used by the mobile device 3 that executes the random access procedure (in step S505), the base station 5 can determine the UE usage type associated with the mobile device 3 even before completing the setup of the radio connection between the base station 5 and the mobile device 3, which is advantageous. It is advantageous that the mobile device 3 can (implicitly) indicate its UE usage type without any need for additional signaling towards the base station 5 (and without any need for signaling with the core network 7).

[0063] Using the information about the service type (UE usage type) associated with the MME and the UE usage type information obtained from the mobile device 3, the base station can more efficiently execute the NNSF in step S509 and select the correct MME for a given mobile device (optionally without any need for core network nodes such as the default MME), which is advantageous. This can thus also reduce the time it takes for the mobile device to register with the MME.

[0064]

Table 1

[0065]

Table 2

[0066] Operation - Second Embodiment FIGS. 6 and 7 show an exemplary timing diagram showing the procedure of the base station 5 that acquires and uses information about the supported service type(s) of the connected MME 9 during the NAS re - routing procedure.

[0067] The base station 5 assumes that each MME 9 is set up by creating a respective S1 connection with each MME 9. The base station 5 is configured to add an entry for each connected MME 9 to the list of entries stored in its MME availability information storage module 69, along with appropriate indication information as to whether that MME is currently available (and, optionally, information identifying the reason why a particular MME is unavailable, e.g., not connected, overloaded, etc.). For each MME 9, the MME availability information storage module 69 also holds information identifying any supported service type(s) corresponding to a plurality of UE usage types (if available). As described above in the first embodiment, it will be understood that the supported service type(s) may be obtained from each connected MME (along with any further MME - specific information shown in Tables 1 and 2).

[0068] As generally shown in step S600, the MME 9D is initially overloaded and thus cannot currently register a plurality of new mobile devices. On the other hand, the mobile device 3D shown in FIG. 6 has an associated usage type corresponding to the usage type supported by this MME 9D.

[0069] This procedure starts when the mobile device 3D generates an NAS message at step S601 and transmits this NAS message to its serving base station 5 (relaying this NAS message to an appropriate dedicated MME). This NAS message may consist of an attach request, a tracking area update (TAU), a location area update (LAU), etc. The mobile device 3D incorporates this NAS message into a suitable RRC message (after performing an appropriate random access procedure if necessary) and transmits this RRC message to the serving base station 5. At step S602, the base station 5 extracts the NAS message from the received RRC message, incorporates this NAS message into an appropriately formatted S1 message, and then transmits it to the default MME 9A.

[0070] In response, the default MME 9A attempts to obtain the UE context associated with the mobile device 3D from the mobile device 3D's previous serving MME 9C (indicated, for example, in the form of an associated GUTI and / or GUMMEI in the received NAS message). To do this, the MME 9A generates an appropriately formatted context request message at step S604 and transmits it to the old MME 9C. The old MME 9C responds by generating an appropriately formatted context request response at step S606 and transmitting it to the default MME 9A, including this UE context and information identifying the UE usage type associated with this mobile device 3D (initially obtained from the HSS 11) in this message.

[0071] Based on the UE usage type included in the context response message (at step S606), the default MME 9A decides to transfer the handling of the mobile device 3D's messages to another MME (i.e., the MME associated with this UE usage type). Therefore, the default MME 9A proceeds to step S610.

[0072] On one hand, in accordance with the overload in step S600, the MME 9D generates, in step S608, an appropriate overload indication message (using its own S1AP module 87) and transmits it to the base station 5 (however, the MME 9D may similarly transmit such indication information to all base stations and / or other MMEs). Upon receiving this message, the base station 5 updates the entry held for this MME 9D in its MME availability information storage module 69 using the information that the MME 9D is unavailable due to overload. Step S608 is shown as being performed following the attach / TAU request message and a plurality of context request / context response messages, but the overload indication information is independent of steps S601 to S606. Therefore, it can be seen that step S608 may be performed at any point following step S600 (for example, even before step S601).

[0073] In step S610, the default MME 9A generates, using its own S1AP module 87, an appropriately formatted S1 signaling message that requests the base station 5 to reroute the NAS message transmitted by the mobile device 3D and transmits it to the base station 5. As shown in FIG. 6, this NAS message rerouting request includes the original (unchanged) NAS message from the mobile device 3D; information identifying the rerouting parameters (for example, the MME group identifier (「MMEGI」) for which the NAS message needs to be rerouted; the globally unique temporary identifier (「GUTI」) associated with the mobile device 3D; information identifying the transmitting MME 9A (for example, by the globally unique MME identifier 「GUMMEI」); and / or information identifying the service type associated with the mobile device 3D (for example, the UE usage type indicated in the UE context response received in S606).

[0074] In this example, the UE usage type associated with the mobile device 3D is supported by a dedicated MME 9D (belonging to the group identified by the MMEGI in S610). On the other hand, the MME 9D is currently overloaded (and, in step S608, has already notified the base station 5 of this overload situation).

[0075] Therefore, in step S612, the base station 5 generates (using its S1AP module 67) a properly formatted S1 response indicating that it cannot reroute the NAS message sent by the mobile device 3D and sends it to the default MME 9A. The base station 5 includes in this message (for example, a "Reroute NAS message failure" message) information identifying the reason why the NAS message sent by the mobile device 3D cannot be rerouted. In this case, the base station 5 indicates that the dedicated MME 9D is overloaded. Moreover, by including the same MMEGI received in step S610, the base station 5 can request the default MME 9A not to reroute the NAS message again (as long as at least the dedicated MME 9D remains overloaded).

[0076] Since the default MME 9A stores the UE context received in step S606, it is therefore advantageous as it can attempt to register and serve the mobile device 3D. If the default MME 9A can register the mobile device 3D, it then generates and sends, in step S616, an appropriate signaling message to confirm to the base station 5 that it has successfully registered the mobile device 3D with this MME 9A. The base station 5 notifies the mobile device 3D of the selected serving MME 9A (in step S617) and acknowledges the receipt of the MME 9A's message (in step S618).

[0077] Figure 7 shows a scenario where the dedicated MME 9D is no longer overloaded.

[0078] As generally shown in step S700, the mobile device 3D starts the procedure by transmitting to the base station 5 an RRC message properly formatted (e.g., an RRC message including an initial UE message for transfer to a proper MME 9). The message of the mobile device 3D includes a NAS message to be transferred to the MME 9 and a GUTI associated with the mobile device 3D (identifying the sender of the NAS message).

[0079] Steps S702 to S706 respectively correspond to steps S602 to S606, and for this reason, their descriptions are omitted here for simplicity.

[0080] On the other hand, in this case, the associated dedicated MME 9D (belonging to the group MMEGI in S710) is available (according to the information held in the MME availability information storage module 69 of the base station 5). Therefore, when the default MME 9A generates an appropriate S1 request to start rerouting the NAS message of the mobile device 3D in step S710 and transmits it to the dedicated MME within the group identified by the MMEGI in this message, the serving base station 5 can respond to this request.

[0081] Therefore, in step S715, the base station 5 generates a properly formatted S1 signaling message (using its own S1AP module 67) and transmits it to the dedicated MME 9D. The base station 5 includes in this S1 message the NAS message (initial UE message) from the mobile device 3D and the GUTI of the mobile device 3D.

[0082] If the dedicated MME 9D can register the mobile device 3D, then, in step S716, it generates and sends an appropriate signaling message to confirm to the base station 5 that it has successfully registered the mobile device 3D with this MME 9D. The base station 5 notifies the serving MME 9D selected for the mobile device 3D (in step S717) and confirms to the MME 9D that the attach procedure has been completed (in step S718).

[0083] In step S722, the base station 5 generates and sends an appropriate S1 message (for example, "NAS message rerouting response" message) to confirm to the default MME 9A that it has successfully redirected the NAS message. The base station 5 also includes in this message a plurality of parameters associated with the UE context of the mobile device 3D (for example, the associated S-TMSI, and "eNB UE S1AP ID").

[0084] Based on the confirmation of the successful rerouting of NAS and the plurality of parameters associated with the UE context of the mobile device 3D, the default MME 9A deletes all UE contexts stored in its memory 79 for this mobile device 3D in step S724.

[0085] When the rerouting of NAS messages is possible (i.e., when the dedicated MME 9D is not overloaded), the default MME 9A is advantageous because it does not need to store unnecessary UE contexts. However, the default MME 9A deletes only the stored UE contexts when receiving confirmation from the base station 5 (at step S722), rather than when sending a NAS message rerouting request (at step S710). In other words, the default MME 9A treats the NAS message rerouting request as a procedure that requires a positive confirmation (i.e., the MME does not automatically consider this procedure as successful) until this procedure is considered successful.

[0086] Operation - Third Embodiment FIGS. 8 and 9 show exemplary timing diagrams illustrating procedures of the base station 5 for obtaining and using information about the supported service type(s) of the connected MME 9 using a downlink NAS transport message (or another suitable S1AP message).

[0087] FIG. 8 generally corresponds to FIG. 6, and FIG. 9 generally corresponds to FIG. 7. However, some of the messages are omitted for clarity. The main difference is that in FIGS. 8 and 9, so-called "downlink NAS transport" requests (those in steps S810 and S910) and corresponding "downlink NAS transport failure" (that in step S812) or "downlink NAS transport response" (that in step S922) are used instead of "NAS message rerouting request" (those in steps S610 and S710), "NAS message rerouting failure" (that in step S612) or "NAS message rerouting response" (step S722), respectively.

[0088] The advantage associated with this solution is that the MME that sends the "NAS message re-routing request" does not currently expect a response to this message (in accordance with the current LTE standard). Therefore, some MMEs (for example, MMEs that implement previous releases of the LTE standard) may not be able to respond to the base station request (in step S612) to register the mobile device 3D that would normally need to be registered with the dedicated MME9D.

[0089] On the other hand, the "downlink NAS transport" request used in FIGS. 8 and 9 always requires a response (success or failure), and therefore, the MME is more likely to be able to understand the base station response to this message (and / or any of the plurality of parameters included in this message).

[0090] Modifications and alternative forms The detailed embodiments have been described above. As will be appreciated by those skilled in the art, a plurality of modifications and alternative forms can be implemented with respect to the above embodiments while still enjoying the benefits derived from the invention embodied in the above embodiments. By way of example only, some of these alternative forms and modifications will be described here.

[0091] In the above embodiments, the mobile device is a cellular phone. As will be appreciated, the above embodiments can be implemented using a plurality of devices other than a plurality of mobile phones, such as a plurality of portable information terminals, a plurality of laptop computers, a plurality of web browsers, etc. The above embodiments are also applicable to non-mobile or generally stationary user equipment.

[0092] The above embodiments are described using the MME for illustrative purposes only and are not to be construed in any way as limiting the present invention to require an MME and / or an LTE core network. For example, an SGSN may be used instead of the MME. In this case, an appropriate SGSN group identifier may be used instead of the MMEGI described in steps S610 / S710 / S810 / S910 above. Embodiments of the present invention are also applicable to systems according to other (3GPP and / or non-3GPP) standards where a user equipment is required to connect to multiple dedicated network nodes.

[0093] In the above description, the MME deletes the stored UE context when it receives confirmation from the base station that the required rerouting of the NAS message has been successful. It will be appreciated that such procedures that require an explicit confirmation (success / failure) are often referred to as class 1 procedures in LTE. In contrast, procedures that do not require any confirmation are automatically considered successful. Such procedures are referred to as class 2 procedures in LTE. The above embodiments advantageously use class 1 procedures so that the base station can respond to the requesting MME as to whether rerouting of the NAS message is possible (and, if not, indicate the reason).

[0094] In the above description of the first embodiment, the mobile device is configured to implicitly indicate the service type / UE usage type to which it is associated by selecting an appropriate random access preamble and transmitting it to the base station. However, it will be appreciated that the mobile device may also provide this information to the base station using appropriately configured low access priority indication information (LAPI) signaling. Additionally, the mobile device may be configured to (explicitly) indicate the UE usage type to which it is associated in its initial attach request message transmitted to the base station (e.g., in step S507). When requesting RRC connection establishment (e.g., using an "RRCConnectionRequest" message), the mobile device may be configured to indicate the UE usage type to which it is associated in this signaling message by, for example, including an appropriately formatted establishment cause in the signaling message. For example, the mobile device may adapt an existing "Delay TolerantAccess-v1020" establishment cause to indicate the UE usage type to which it is associated, or may use any other (new) establishment cause suitable for indicating a particular UE usage type.

[0095] In the above embodiment, it was described that the serving base station selects the default MME in the case of overloading of the dedicated MME. However, it will be appreciated that the base station may select a different MME (e.g., a common MME) instead of the default MME depending on the operator's configuration. Such a selection configuration may be applied for each UE usage type / MMEGI / MME, etc. When the base station is configured to select an MME different from the default MME, it may generate an appropriate S1 message and transmit it to the selected MME (instead of responding to the default MME as in step S612 or S812), and this message may include the NAS message of the mobile device and information identifying the reason why the dedicated MME cannot be used (e.g., the information included in the message in step S612).

[0096] It will be appreciated that the above embodiments may also be applicable to heterogeneous / partial DCN deployments when the DCN is deployed for only some (but not all) of the RATs and / or only for specific areas within the network. In this case, the base stations and the MMEs may be configured to take into account whether the UE is within or outside a specific service area or the RAT that supports the DCN.

[0097] In the above embodiments, a plurality of software modules have been described. As will be appreciated by those skilled in the art, those software modules may be provided in a compiled or uncompiled form, and may be supplied to the base station or the MME as a signal via a computer network or in a recording medium. Further, the functions executed by some or all of this software may be executed using one or more dedicated hardware circuits. However, the use of software modules is preferred because it facilitates the updating of the base station, the MME, and the mobile device in order to update the functions of the base station, the MME, and the mobile device.

[0098] The transceiver of the communication device may be operable to receive from the dedicated MME information identifying the communication load of the dedicated MME, and the controller may be operable to determine, based on the information identifying the communication load of the dedicated MME, whether the dedicated MME is suitable for serving the communication device that transmitted the signaling to establish the communication connection. In this case, the transceiver of the communication device may be operable to receive from the dedicated MME information identifying the service type related to the information identifying the communication load of the dedicated MME.

[0099] The transceiver of the communication device may be operable to receive from the dedicated MME an MME overload message including the information identifying the service type related to the information identifying the communication load of the dedicated MME.

[0100] The message for identifying the dedicated MME may consist of at least one of a NAS message rerouting request and a downlink NAS transport request. The response to the default MME may consist of at least one of a NAS message rerouting failure and a downlink NAS transport failure. The response to the default MME may include information identifying a factor for which the rerouting to the dedicated MME is unsuccessful (e.g., due to the load of the dedicated MME).

[0101] The transceiver of the communication device may be operable to receive signaling for establishing a communication connection from at least one communication device within the communication cell via the communication device, and the signaling for establishing the communication connection consists of information identifying a usage type associated with the at least one communication device. In this case, the controller of the communication device may be operable to identify at least one MME that supports a communication device having a usage type corresponding to at least one service type supported by the MME, based on the information identifying the usage type and the respective information identifying the at least one support service type.

[0102] The controller (of the communication device) may be operable to route the communication connection to the at least one MME that supports a communication device having a usage type corresponding to at least one service type supported by the at least one MME.

[0103] The transceiver (of the communication device) may be operable to receive, using at least one of an S1 setup response message and an MME configuration update message, the information identifying a group associated with a specific MME and the information identifying the at least one support service type of the specific MME.

[0104] The information for identifying the at least one support service type of a specific MME may consist of at least information elements (for example, "service type list" information element, "UE service type" information element, and / or "UE usage type" information element).

[0105] (The transceiver of the communication device) may be operable to receive information for identifying the communication load of the at least one MME.

[0106] The information for identifying the usage type associated with the communication device may consist of low access priority indication information (LAPI) and / or connection establishment factors (for example, those in the "RRCConnectionRequest" message).

[0107] The information for identifying the usage type associated with the communication device may consist of a random access preamble associated with that usage type. The communication device may be operable to transmit, within the communication cell (for example, via system broadcast), the information for identifying at least one support service type and each set of random access preambles associated with the at least one support service type. In this case, (the transceiver of the communication device) may be operable to receive, from the communication device (for example, via system broadcast), the information for identifying at least one support service type and each set of random access preambles associated with the at least one support service type, and the controller may be operable to select a preamble for transmission by the transceiver based on the received information for identifying at least one support service type and each set of random access preambles associated with the at least one support service type.

[0108] The MME may further comprise a memory configured to store a UE context associated with the communication device having the associated usage type, and a processor operable to control the memory such that (a) when the response indicates that rerouting to the dedicated MME is unsuccessful, the UE context associated with the communication device having the associated usage type is retained in the memory, and (b) when the response indicates that rerouting to the dedicated MME is successful, the UE context associated with the communication device having the associated usage type is not retained in the memory.

[0109] Various other modifications will be apparent to those skilled in the art and are not described in further detail herein.

[0110] This application claims priority to British Patent Application No. 1514540.2, filed on Aug. 14, 2015, the disclosure of which is incorporated herein in its entirety.

Claims

1. Means for broadcasting system information including information indicating an association between at least one service used by a user equipment and respective radio access preambles; Means for receiving, from the user equipment that has received the system information, a message including the radio access preamble corresponding to one of the at least one service selected based on the information indicating the association; Means for selecting at least one core network node corresponding to one of the at least one service; A radio access network node comprising the above.

2. A user equipment, comprising: Means for receiving system information including information indicating an association between at least one service used by the user equipment and respective radio access preambles; Means for transmitting, to the radio access network node that has transmitted the system information, a message including the radio access preamble corresponding to one of the at least one service, for the radio access network node to select at least one core network node corresponding to one of the at least one service. A user equipment.

3. Broadcasting system information including information indicating an association between at least one service used by a user equipment and respective radio access preambles; Receiving, from the user equipment that has received the system information, a message including the radio access preamble corresponding to one of the at least one service selected based on the information indicating the association; Selecting at least one core network node corresponding to one of the at least one service; A method in a radio access network node, including the above.

4. A method in a user equipment, including: Receiving system information including information indicating an association between at least one service used by the user equipment and respective radio access preambles; To cause the radio access network node that transmitted the system information to select at least one core network node corresponding to one of the at least one service for the radio access network node, transmitting a message including the radio access preamble corresponding to one of the at least one service. Method.

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