Abstract:
The present invention relates to a solution for paging of idle user equipment and in particular for changing mode status from idle to connected in an efficient manner. This is provided in a method, nodes, and a system arranged to determine a suitable paging message related to a framework table indicating selection criteria entries for access point name, quality of service class indicator, IMSI number, and IMEI number and determining from the framework table a paging granularity set to be used in the paging request from a granularity table comprising entries for paging areas, number of paging retries, and time between retransmissions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a 35 U.S.C. §371 National Phase Entry Application from PCT/EP2010/058009, filed Jun. 8, 2010, and designating the United States, and claiming priority to U.S. Provisional Application No. 61/239,300, filed Sep. 2, 2009, the entire contents of said applications are incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a solution for paging of idle user equipment and in particular for changing mode status from idle to connected in an efficient manner. 
     BACKGROUND 
     When the number of subscribers grows in the EPC (Evolved Packet Core) network every optimization possible is needed to fulfil the requirements from the industry. 
     The suggested way (see for instance 3GPP TS 23.401) to move a user equipment (UE) from EPS Connection Management ECM-IDLE state to ECM-Connected, meaning that the UE can receive downlink payload, is to do this on a UE level, this will make it impossible to initiate different paging procedures on a service level. 
     From 23.401, v8.5.0 the overall procedure looks like illustrated in  FIG. 2 . 
     If a mobility management entity (MME) needs to signal with the UE that it is in ECM-IDLE state, e.g. to perform an MME/HSS-initiated detach procedure for the ECM-IDLE mode UE or a Serving Gateway (SGW) receives control signalling (e.g. Create Dedicated Bearer Request or Modify Dedicated Bearer Request), the MME starts network triggered service request procedure from step  206 . 
     If Idle mode Signalling Reduction (ISR) is activated, when the SGW receives a Create Dedicated Bearer Request or Modify Bearer Request for a UE, and the SGW does not have a downlink S1-U and the SGSN has notified the SGW that the UE has moved to PMM-IDLE or STANDBY state, the SGW buffers signalling messages and triggers MME and SGSN to page UE. In this case the SGW will be notified about the current Radio Access Technology (RAT) type based on the UE triggered service request procedure. The SGW will go on executing the dedicated bearer activation or dedicated bearer modification procedure, i.e. send the corresponding buffered signalling to MME or SGSN which UE resides in now and inform the current RAT type to a Packet Data Network Gateway (PGW) if the RAT type has been changed compared to the last reported RAT Type. If dynamic Policy and Charging Control (PCC) is deployed, the current RAT type information shall also be conveyed from the PGW to a Policy and Charging Rules Function (PCRF). If the PCRF response leads to an EPS bearer modification the PGW should initiate a bearer update procedure. 
     There are a number of problems with existing solutions, such as it is not possible to initiate different paging procedures for one specific UE or that there will be increased processing load in the MME since the MME has to page rather large areas to be able to secure that the UE is reached. 
     SUMMARY 
     It is therefore an object of the present invention to provide solutions that addresses these problems. This is provided in a number of aspects in which a first is a method for handling paging of user equipment communicating wirelessly with a telecommunications network. The method is executed in a mobility management entity (MME) and first the MME receives from a serving gateway a downlink data notification comprising information about at least one bearer identification. Further, the MME determines a paging request based on the bearer identification and a framework table comprising selection criteria entries for access point name, quality of service class indicator, IMSI number, and IMEI number and determines from the framework table a paging granularity set to be used in the paging request from a granularity table comprising entries for paging areas, number of paging retries, and time between retransmissions. Finally, the MME sends the paging request to a radio access network node. 
     The paging areas may comprise at least one of eNodeB, tracking area, part of tracking area list, and tracking area list and wherein the downlink data notification may indicate that a user equipment state is to be changed from idle mode to connected mode. The downlink data notification may comprise an information element with the bearer identification. 
     The mobility management node may be at least one of mobility management entity (MME) or a Serving GPRS support node (SGSN). 
     The framework table may further comprise an allocation and retention priority entry. The radio access network node may be an eNodeB. 
     Another aspect of the present invention is provided, a mobility management node used in paging procedure of user equipment in a wireless communication network. The node may comprise a processor, a computer readable memory, and a communication interface. The processor may be arranged to execute instruction sets stored in the memory and using the communication interface for receiving from a serving gateway a downlink data notification comprising information about at least one bearer identification, determining a paging request based on a framework table comprising selection criteria entries for access point name, quality of service class indicator, IMSI number, and IMEI number and determining from the framework table a paging granularity set to be used in the paging request from a granularity table comprising entries for paging areas, number of paging retries, and time between retransmissions, and sending the paging request to a radio access network node. 
     Yet another aspect of the present invention is provided, a computer program stored in a computer readable storage medium in a mobility management entity. The computer program may comprise instruction sets for receiving from a serving gateway a downlink data notification comprising information about at least one bearer identification, determining a paging request based on the bearer identification and a framework table comprising selection criteria entries for access point name, quality of service class indicator, IMSI number, and IMEI number and determining from the framework table a paging granularity set to be used in the paging request from a granularity table comprising entries for paging areas, number of paging retries, and time between retransmissions; and sending the paging request to a radio access network node. 
     In communication with MME is a serving gateway node used in paging of user equipment in a wireless communication network. The node may comprise a processor, a computer readable memory, a communication interface. The processor may be arranged to execute instruction sets stored in the memory and using the communication interface for determining that a downlink data notification message is to be sent to a mobility management node, providing an identification extension information element in the downlink data notification message, and sending the downlink data notification message to the mobility management node. The identification extension may be an evolved packet system bearer identification. The downlink data notification message may be sent on an S11 interface between the serving gateway node and a mobility management entity, i.e. MME, and/or the downlink data notification message may be sent on an S4 interface between the serving gateway node and a serving GPRS support node, i.e. SGSN. 
     Furthermore, a system according to the present invention for use in a wireless communication network is provided. The system may comprise an access gateway node handling wireless communication with a user equipment, a mobility management node as described above in communication with the access gateway node; and a serving gateway node as described above in communication with the mobility management node. 
     With the above mentioned aspects of the present invention it is provided paging differentiation, and this document shows examples of how to implement a solution relating to paging between the MME and a radio network access node, e.g. an eNodeB. The present invention provides two parts in the solution: first a framework is created in the MME handling how each and every UE should be paged depending on different criteria and scenarios and secondly the message protocol between SGW and MME is extended to include information for determining the framework. 
     This is solved by introducing an information element (IE) with proprietary configuration or to add an extension to the existing IE related to downlink data notification. 
     With the solution according to the present invention, there are a number of advantages, such as providing
         flexible paging procedural handling;   possibility to minimize signalling load over air;   possibility to minimize signalling load in network; and   possibility to minimize processing load in the MME       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following the invention will be described in a non-limiting way and in more detail with reference to exemplary embodiments illustrated in the enclosed drawings, in which: 
         FIG. 1  illustrates schematically a network according to the present invention; 
         FIG. 2  illustrates schematically in a signaling diagram a method according to the present invention; 
         FIG. 3  illustrates schematically a network architecture with interfaces according to the present invention; and 
         FIG. 4  illustrates schematically a device according to the present invention; 
     
    
    
     DETAILED DESCRIPTION 
     In  FIG. 1  reference numeral  100  generally denote a network according to the present invention. An infrastructure network  104  connects infrastructure entities with each other for handling control and data traffic to and from user equipment  101  (UE). The UE may be connected wirelessly to a EUTRAN based network via an eNodeB  103  or wirelessly  108  to a GERAN or UTRAN based network via an RNC/BSC  102 . Mobility managing nodes are provided, e.g. mobility management entity (MME)  105  and/or serving GPRS support node (SGSN)  109 . Gateway handling nodes are also provided, e.g. GGSN  110  and/or Packet Data Network Gateway  107  (PGW). Furthermore, a Serving Gateway (SGW)  106  may be provided. 
       FIG. 2  illustrates a signalling flow for moving a UE from idle mode to connected mode. In order to introduce paging differentiation step  206  is addressed as will be discussed later in this document. The flow is as follows: 
       201 . When the SGW receives a downlink data packet for a UE known as not user plane connected (i.e. the SGW context data indicates no downlink user plane Tunnel Endpoint Identifier (TEID)), it buffers the downlink data packet and identifies which MME or SGSN is serving that UE. 
     If that MME has requested the SGW to delay sending the Downlink (DL) Data Notification (DDN) (see clause 5.3.4.2 on “Handling of abnormal conditions in UE triggered Service Request” in TS 23.401 v9.1.0), the SGW buffers the downlink data and waits until the timer expires before continuing with step  2 . If a DL-TEID and eNodeB address for that UE is received before the expiry of the timer, the timer shall be cancelled and the Network triggered Service Request procedure is finished without executing the steps below, i.e. DL data are sent to the UE. 
     If the SGW receives additional downlink data packets for this UE before the expiry of the timer, the SGW does not restart this timer. 
       202 - 205 . The SGW sends a Downlink Data Notification message to the MME and SGSN nodes for which it has control plane connectivity for the given UE. The MME and SGSN respond to the SGW with a Downlink Data Notification Acknowledgement (Ack) message. 
     If the SGW receives additional downlink data packets for this UE, the SGW buffers these downlink data packets and the SGW does not send a new Downlink Data Notification. 
       206 . If the UE is registered in the MME, the MME sends a Paging message (comprising entries for NAS ID for paging, TAI(s), UE identity based DRX (Discontinuous Reception) index, Paging DRX length) to each eNodeB belonging to the tracking area(s) in which the UE is registered. The step is described in detail in TS 36.300 and TS 36.413. Steps  206 - 209  are omitted if the MME already has a signalling connection over S1-MME towards the UE.
 
 207 . If the UE is registered in the SGSN, the SGSN sends paging messages to RNC/BSS, which is described in detail in TS 23.060.
 
 208 . If eNodeBs receive paging messages from the MME, the UE is paged by the eNodeBs. The step is described in detail in TS 36.300 and TS 36.304.
 
 209 . If RNC/BSS/BSC nodes receive paging messages from the SGSN the UE is paged by the RN(S)C/BSS/BSC, which is described in detail in TS 23.060.
 
 210 . Upon reception of paging indication in E-UTRAN access, the UE initiates the UE triggered Service Request procedure, which is specified in clause 5.3.4.1 in TS23.401. Upon reception of paging indication in UTRAN or GERAN access, the UE shall respond in respective access as specified TS 24.008 and the SGSN shall notify the SGW.
 
     The MME and/or SGSN supervise the paging procedure with a timer. If the MME and/or SGSN receive no response from the UE to the Paging Request message, it may repeat the paging. The repetition strategy is operator dependent. 
     If the MME and/or SGSN receive no response from the UE after this paging repetition procedure, it shall use the Downlink Data Notification Reject message to notify the SGW about the paging failure. In that case, if ISR is not activated, the SGW deletes the buffered packet(s). If ISR is activated and the SGW receives paging failure from both SGSN and MME, the SGW deletes the buffered packet(s) or rejects the control signalling which triggers the Service Request procedure. 
       211 . If ISR is activated and paging response is received in E UTRAN access the SGW sends a “Stop Paging” message to the SGSN. 
       212 . If ISR is activated and paging response is received in UTRAN or GERAN access the SGW sends a “Stop Paging” message to the MME. 
       213 - 214 . The SGW transmits downlink data towards the UE only via the RAT where paging response was received depending on what configuration is present. 
     Downlink data may be transferred when mode is changed to connected. 
     In step  206  above a paging differentiation solution may be provided by first creating a framework in the MME handling how each and every UE should be paged depending on different criteria and scenarios—these selection criteria and scenarios will be discussed below. The MME reacts from an extension in the downlink data notification message from the SGW to the MME—this extension will be discussed in more detail below. 
     When the MME is informed that downlink data for a UE is waiting for transmittal, a paging message is to be sent downlink towards the UE in order to change the state of the UE from IDLE to CONNECTED. In order to reduce the load on the infrastructure due to paging procedures, a framework may be provided in the MME comprising selection criteria and a wanted paging granularity. The selection criteria may be based on a combination of access point name (APN), Quality of Service (QoS) Class Identifier (QCI), International Mobile Equipment Identity Number Series (IMEINS), and International Mobile Subscriber Identity Number Series (IMSINS). Based on the selection criteria a wanted granularity may be provided, wherein the granularity may comprise a combination of eNodeB (eNB), Tracking Area (TA), part of a TA identifier (TAI) list, and a TAI list. Furthermore, the framework may comprise information about number of retransmissions of and time between retransmissions. 
     In summary, the framework with, at least, the following criteria may be provided in the MME: 
     1) Selection Criteria: 
     comprising APN, 
     
         
         
           
             QCI, 
             IMEINS, 
             IMSINS
 
2) Wanted granularity:
 
comprising eNodeB (evolved NodeB),
 
             TA (tracking area), 
             Part of TAI list (TA Identifier list), 
             TAI List.
 
3) Number of retransmissions
 
4) Time between retransmissions
 
           
         
       
    
     This will make it possible for the operator to have a flexible way of adapting the paging load in accordance with the current network topology situation. 
     The configuration of the framework may be done using either CLI (Command Line Interface) or MMI (Man Machine Interface). 
     The result will be two tables looking for example like this, but it should be appreciated that these are only examples of tables shown for illustrative purposes: 
     
       
         
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                 IMEI 
                   
               
               
                   
                   
                 IMSI number 
                 number 
               
               
                 APN 
                 QCI 
                 Series 
                 Series 
                 Granularity Set 
               
               
                   
               
             
             
               
                 X 
                 1-4 
                 X 
                 X 
                 1 (see table below) 
               
               
                 X 
                 5 
                 X 
                 X 
                 2 (see table below) 
               
               
                 X 
                 6-9 
                 X 
                 X 
                 3 (see table below) 
               
               
                 X 
                 X 
                 12345 
                 X 
                 4 (see table below) 
               
               
                   
                   
                   
                   
                 Specially selected 
               
               
                   
                   
                   
                   
                 subscriber groups. 
               
               
                 X 
                 X 
                 X 
                 12345 
                 4 (see table below) 
               
               
                   
                   
                   
                   
                 Used in combination 
               
               
                   
                   
                   
                   
                 with laptop modems 
               
               
                 vendor.se 
                 X 
                 X 
                 X 
                 1 (see table below) 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Number 
                 Time 
               
               
                 Granularity 
                   
                 Area 
                   
                   
                 of 
                 between 
               
               
                 Set 
                 Area 1 
                 2 
                 Area 3 
                 Area4 
                 re-tries 
                 areas (s) 
               
               
                   
               
             
             
               
                 1 
                 X 
                 X 
                 TA List, 
                 TAI List 
                 2 
                 1 
               
               
                   
                   
                   
                 TA 1-3) 
               
               
                 2 
                 X 
                 TA 
                 TA List, 
                 TAI List 
                 1 
                 2 
               
               
                   
                   
                   
                 TA 1-3) 
               
               
                 3 
                 eNB 
                 TA 
                 TA List, 
                 TAI List 
                 1 
                 2 
               
               
                   
                   
                   
                 TA 1-3) 
               
               
                 4 
                 eNB 
                 TA 
                 X 
                 X 
                 2 
                 1 
               
               
                   
               
             
          
         
       
     
     To make this possible, information is to be sent from SGW to MME to provide the MME with information to handle the situation correctly, and there are two possible ways to do this, either
         1. a proprietary solution for a vendor/operator using the private extension (see message below); or to   2. update the standard message in 3GPP TS 29.274.       

     Downlink Data Notification message is described in 3GPP TS 29.274. A Downlink Data Notification message shall be sent on the S11 interface by the SGW to the MME as a part of the network triggered service request procedure. 
     The message shall also be sent on the S4 interface by the SGW to the SGSN as part of Paging with no established user plane on S4, SGW triggered paging with S4. 
     Table 3 below specifies the presence of the IEs in the message. 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Information Elements in a Downlink Data Notification 
               
             
          
           
               
                 Information 
                   
                   
                   
                   
               
               
                 elements 
                 P 
                 Condition/Comment 
                 IE Type 
                 Ins. 
               
               
                   
               
               
                 Private Extension 
                 O 
                   
                 Private 
                 VS 
               
               
                   
                   
                   
                 Extension 
               
               
                   
               
             
          
         
       
     
     Solution 1 is to use an already present information element (IE) Private Extension. However, this only works for a single vendor network. A single vendor network comprises nodes delivered by a single vendor, i.e. all nodes are made by the same vendor and therefore may work with proprietary interfaces and solutions if so wanted. 
     Solution 2 is to add an IE to the downlink data notification message, which thus may look like this: 
     
       
         
               
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                 Information 
                   
                   
                   
                   
               
               
                 elements 
                 P 
                 Condition/Comment 
                 IE Type 
                 Ins. 
               
               
                   
               
             
             
               
                 EPS Bearer ID 
                 O 
                 This IE shall contain the 
                 EBI 
                 0 
               
               
                   
                   
                 bearer that SGW has 
               
               
                   
                   
                 received downlink payload 
               
               
                   
                   
                 for. 
               
               
                 Private Extension 
                 O 
                   
                 Private 
                 VS 
               
               
                   
                   
                   
                 Extension 
               
               
                   
               
             
          
         
       
     
     In this second solution a separate EPS bearer ID information element is used to signal that the SGW has received downlink payload for the UE and that the mode of the UE is to be changed. Solution 2 makes it possible to use in an all vendor network. 
     The solution according to the present invention may be provided in a 3GPP based network  300  as depicted in  FIG. 3 . The 3GPP network may comprise a core network part and an E-UTRAN access network part  301 . The core network part may comprise a mobility management entity (MME)  105 , a serving gateway (SGW)  106 , a packet data network gateway (PGW)  107 , a policy and charging rules function node (PCRF)  302 , and a home subscriber server (HSS)  304 . The MME is in communication with the access network  301  via an S1-MME interface, a serving GPRS support node (SGSN)  109  via an S3 interface, the HSS via an S6a interface, and the SGW via an S11 interface. The SGW is in turn connected to the access network  301  via an S1-U interface, the SGSN via an S4 interface, and the PGW via an S5 interface. Furthermore, the SGW is connected to a UTRAN based access network  306 . The SGSN  109  is also connected to the UTRAN based access network and to a GERAN based access network  305 . The PGW is connected to the PCRF via a Gx interface and each of the PGW and the PCRF is connected to an Operators IP services via SGi and Rx interfaces respectively. The operators IP services may comprise e.g. IMS and PSS. The UE  101  is connected to the E-UTRAN access network via an LTE-Uu interface. 
     The solution according to the present invention involves core network nodes  400 , e.g. the MME, as illustrated in  FIG. 4 , which comprise a processor  401 , a computer readable storage medium  402 , and at least one communication interface  404 . Optionally, the node  400  also comprises a user interface  403 . The processor is arranged to execute instruction sets of computer software code, stored in the memory, for handling steps according to the present invention: e.g. handling the information element used for paging purposes. The invention also involves a mobility management node, e.g. SGW or SGSN, which comprise similar units, i.e. at least one processor, memory, and communication interface— FIG. 4  may be reused for illustrating these nodes as they are built with such similar components. The SGW provides a message comprising information about the location of the UE. This message is provided as part of the paging process and is transmitted in the network as a signal. The infrastructure network further comprises other network nodes as high level nodes as for instance shown in  FIGS. 1 and 3 ; furthermore, the network may comprise basic network routing and switching elements for transmitting control and data traffic in the network. 
     In short, a method facilitating changing mode of user equipment in a wireless communication network may be summarized as follows: The method comprising the steps of:
         determining if a mode of a user equipment, i.e. UE, is to be changed from idle mode to connected mode;   providing a message used in a paging process in a core network node;   providing in the message an information element, i.e. IE, comprising information related to location of UE in the communication network; the location information is used for executing a paging process.       

     The references mentioned in this document are incorporated into this document by reference. 
     It should be noted that with computer program is meant any type of instruction sets that may be executed by a processor. It may be software instruction sets or hardware instruction sets depending on type of processing device, e.g. microprocessor, CPU, FPGA (field programmable gate array), ASIC (application specific integrated circuit), or similar devices. 
     With computer readable storage medium is meant any type of storage medium accessible by a processing device, and the storage medium may be of volatile and/or non-volatile type. 
     It should be noted that the word “comprising” does not exclude the presence of other elements or steps than those listed and the words “a” or “an” preceding an element do not exclude the presence of a plurality of such elements. It should further be noted that any reference signs do not limit the scope of the claims, that the invention may be at least in part implemented by means of both hardware and software, and that several “means” or “units” may be represented by the same item of hardware. 
     Modifications and other embodiments of the disclosed invention(s) will come to mind to one skilled in the art having the benefit of the teachings present in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention(s) is/are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of this disclosure. Although specific terms may be employed herein, they are used in a generic and descriptive sense only and not for purpose of limitation. 
     The above mentioned and described embodiments are only given as examples and should not be limiting to the present invention. Other solutions, uses, objectives, and functions within the scope of the invention as exemplified in the below described embodiments should be apparent for the person skilled in the art. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 ABBREVIATIONS 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 APN 
                 Access Point Name 
               
               
                 APN-NI 
                 Access Point Name Network Identifier 
               
               
                 APN-OI 
                 Access Point Name Operator Identifier 
               
               
                 ARP 
                 Allocation and Retention Priority 
               
               
                 BSC 
                 Base station controller 
               
               
                 BS 
                 Base station 
               
               
                 BSS 
                 Base station system 
               
               
                 CLI 
                 Command Line Interface 
               
               
                 CPU 
                 Central Processing Unit 
               
               
                 CSG ID 
                 Closed Subscriber Group Identity 
               
               
                 CSG 
                 Closed Subscriber Group 
               
               
                 DB 
                 Data Base 
               
               
                 EBI 
                 EPS Bearer ID 
               
               
                 ECGI 
                 E-UTRAN Cell Global Identifier 
               
               
                 ECM 
                 EPS Connection Management 
               
               
                 EDGE 
                 Enhanced Data rates for GSM Evolution 
               
               
                 EMM 
                 EPS Mobility Management 
               
               
                 eNB 
                 Evolved NodeB 
               
               
                 eNodeB 
                 Evolved Node B 
               
               
                 EPC 
                 Evolved Packet Core 
               
               
                 EPS 
                 Evolved Packet System 
               
               
                 E-RAB 
                 E-UTRAN Radio Access Bearer 
               
               
                 E-UTRAN 
                 Evolved Universal Terrestrial Radio Access Network 
               
               
                 GERAN 
                 GSM/EDGE Radio Access Network 
               
               
                 G-PDU 
                 GTP-U non-signalling PDU 
               
               
                 GPRS 
                 General Packet Radio Service 
               
               
                 GSM 
                 Global System for Mobile communications 
               
               
                 GTP 
                 GPRS Tunnelling Protocol 
               
               
                 GUMMEI 
                 Globally Unique MME Identifier 
               
               
                 GUTI 
                 Globally Unique Temporary Identity 
               
               
                 GW 
                 Gateway 
               
               
                 HSS 
                 Home subscriber server 
               
               
                 IEEE 
                 Institute of Electrical and Electronics Engineers 
               
               
                 IMEINS 
                 International Mobile Equipment Identity Number Series 
               
               
                 IMSI 
                 International Mobile Subscriber Identity 
               
               
                 IMSINS 
                 International Mobile Subscriber Identity Number Series 
               
               
                 IP 
                 Internet Protocol 
               
               
                 ISR 
                 Idle mode Signalling Reduction 
               
               
                 LTE 
                 Long Term Evolution 
               
               
                 MBR 
                 Maximum Bit Rate 
               
               
                 MEI 
                 Mobile Equipment Identity 
               
               
                 MME 
                 Mobility Management Entity 
               
               
                 MMEC 
                 MME Code 
               
               
                 MMI 
                 Man Machine Interface 
               
               
                 MSISDN 
                 Mobile Subscriber ISDN Number 
               
               
                 NAK 
                 Negative AcKnowledgement 
               
               
                 NAS 
                 Non Access Stratum 
               
               
                 PCC 
                 Policy and Charging Control 
               
               
                 PCRF 
                 Policy and Charging Rules Function 
               
               
                 PDCP 
                 Packet Data Convergence Protocol 
               
               
                 PDN 
                 Packet Data Network or Public Data Network 
               
               
                 PDN-GW 
                 Packet Data Network GateWay 
               
               
                 PDU 
                 Protocol Data Unit 
               
               
                 PGW 
                 PDN Gateway 
               
               
                 PMIP 
                 Proxy Mobile IP 
               
               
                 QCI 
                 QoS Class Identifier 
               
               
                 QoS 
                 Quality of Service 
               
               
                 RAT 
                 Radio Access Technology/Type 
               
               
                 RCI 
                 RAT Connection Information 
               
               
                 RIM 
                 RAN Information Management 
               
               
                 RNC 
                 Radio network controller 
               
               
                 RNS 
                 Radio network system 
               
               
                 Rx 
                 Reception 
               
               
                 SGSN 
                 Serving GPRS Support Node 
               
               
                 SGW 
                 Serving Gateway 
               
               
                 S-TMSI 
                 S-Temporary Mobile Subscriber Identity 
               
               
                 TA 
                 Tracking Area 
               
               
                 TAC 
                 Tracking Area Code 
               
               
                 TAD 
                 Traffic Aggregate Description 
               
               
                 TAI 
                 Tracking Area Identity 
               
               
                 TAU 
                 Tracking Area Update 
               
               
                 TEID 
                 Tunnel Endpoint Identifier 
               
               
                 TEID-C 
                 Tunnel Endpoint Identifier, control plane 
               
               
                 TEID-U 
                 Tunnel Endpoint Identifier, user plane 
               
               
                 TFT 
                 Traffic Flow Template 
               
               
                 Tx 
                 Transmission 
               
               
                 UDP 
                 User Datagram Protocol 
               
               
                 UE 
                 User Equipment 
               
               
                 UL TFT 
                 UpLink Traffic Flow Template 
               
               
                 UTRAN 
                 Universal Terrestrial Radio Access Network 
               
               
                 W-CDMA 
                 Wideband Code Division Multiple Access 
               
               
                   
               
             
          
         
       
     
     REFERENCES AND DEFINITIONS 
     3GPP TS23.401 
     MME Pool Area: An MME Pool Area is defined as an area within which a UE may be served without need to change the serving MME. An MME Pool Area is served by one or more MMEs (“pool of MMEs”) in parallel. MME Pool Areas are a collection of complete Tracking Areas. MME Pool Areas may overlap each other.
 
SGW Service Area: A SGW Service Area is defined as an area within which a UE may be served without need to change the SGW. A SGW Service Area is served by one or more SGWs in parallel. SGW Service Areas are a collection of complete Tracking Areas. SGW Service Areas may overlap each other.
 
PDN Connection: The association between a UE represented by one IPv4 address and/or one IPv6 prefix and a PDN represented by an APN.
 
Default Bearer: The EPS bearer which is first established for a new PDN connection and remains established throughout the lifetime of the PDN connection.
 
Default APN: A Default APN is defined as the APN which is marked as default in the subscription data and used during the Attach procedure and the UE requested PDN connectivity procedure when no APN is provided by the UE.
 
     EPS Mobility Management and Connection Management states 
     The EPS Mobility Management (EMM) states describe the Mobility Management states that result from the mobility management procedures e.g. Attach and Tracking Area Update procedures. 
     Two EMM states are described in this document:
         EMM-DEREGISTERED.   EMM-REGISTERED.       

     In the EMM DEREGISTERED state, the EMM context in MME holds no valid location or routeing information for the UE. The UE is not reachable by a MME, as the UE location is not known. 
     In the EMM-DEREGISTERED state, some UE context can still be stored in the UE and MME, e.g. to avoid running an AKA procedure during every Attach procedure. The UE enters the EMM-REGISTERED state by a successful registration with an Attach procedure to either E-UTRAN or GERAN/UTRAN. The MME enters the EMM-REGISTERED state by a successful Tracking Area Update procedure for a UE selecting an E-UTRAN cell from GERAN/UTRAN or by an Attach procedure via E-UTRAN. In the EMM-REGISTERED state, the UE can receive services that require registration in the EPS. 
     A UE is in ECM-IDLE state when no NAS signalling connection between UE and network exists. 
     In ECM-CONNECTED mode, the UE location is known in the MME with an accuracy of a serving eNodeB ID. The mobility of UE is handled by the handover procedure. 
     The UE performs the tracking area update procedure when the TAI in the EMM system information is not in the list of TA&#39;s that the UE registered with the network, or when the UE handovers to an E UTRAN cell and the UE&#39;s TIN indicates “P-TMSI”. 
     For a UE in the ECM-CONNECTED state, there exists a signalling connection between the UE and the MME. The signalling connection is made up of two parts: an RRC connection and an S1_MME connection. 
     The UE shall enter the ECM-IDLE state when its signalling connection to the MME has been released or broken. This release or failure is explicitly indicated by the eNodeB to the UE or detected by the UE. 
     The S1 release procedure changes the state at both UE and MME from ECM-CONNECTED to ECM-IDLE. 
     3GPP TS 29.274