Abstract:
The present invention relates to a solution for handling an evolved allocation and retention priority in a telecommunications network. The solution is based on obtaining an evolved ARP, obtaining an authorized ARP based on the evolved ARP, and transmitting this authorized ARP to nodes in the network. Furthermore, the authorized ARP may be included in information elements involved in mobility procedure messages.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a solution for handling an evolved allocation and retention priority in a telecommunications network. 
       BACKGROUND 
       [0002]    Allocation and retention priority was introduced into 2G/3G packet network according to TS 3GPP 23.107. It is used to specify the relative importance compared to other UMTS bearers for allocation and retention of the UMTS bearer. Priority is used for differentiating between bearers when performing allocation and retention of a bearer. In situations where resources are scarce, the relevant network elements can use the Allocation/retention Priority to prioritize bearers with a high Allocation/retention Priority over bearers with a low Allocation/Retention Priority when performing admission control. 
         [0003]    The Allocation/Retention Priority attribute is a subscription attribute which is not negotiated from the mobile terminal, but the value might be changed either by the SGSN or the GGSN network element. 
         [0004]    By introducing new services into packet domain such as multiple priority service, the Allocation and Retention Priority is evolved. 
         [0005]    The evolved ARP comprises information about the priority level (scalar), the pre-emption capability (flag), and the pre-emption vulnerability (flag). The priority level defines the relative importance of a resource request. This allows deciding whether a bearer establishment or modification request may be accepted or needs to be rejected in case of resource limitations (typically used for admission control of GBR traffic). It may also be used to decide which existing bearers to pre-empt during resource limitations. 
         [0006]    The range of the ARP priority levels is 1 to 15 with  1  as the highest level of priority. The pre-emption capability information defines whether a service data flow may get resources that were already assigned to another service data flow with a lower priority level. The pre-emption vulnerability information defines whether service data may lose the resources assigned to it in order to admit a service data flow with higher priority level. The pre-emption capability and the pre-emption vulnerability may be either set to “yes” or “no”. 
         [0007]    For example, video telephony is one use case where it may be beneficial to use EPS bearers with different ARP values for the same UE. IN this use case an operator could map voice to one bearer with a higher ARP and video to another bearer with a lower ARP. In a congestion situation (e.g. at call edge) the eNB may then drop the “video bearer” without affecting the “voice bearer”. This would improve service continuity. 
         [0008]    In the current packet core network, according to 3GPP 23.107 (table 4): value ranges for UMTS bearer service attributes, (ARP) Allocation/retention Priority is defined as a scalar with a range 1-3 which has been implemented at the Gr interface and Gn/Gp interface. 
         [0009]    How to introduce the Evolved ARP and at the same time to avoid the backwards compatibility issues becomes a problem. 
         [0010]    PDG-GW supporting E-UTRAN access with MME/S4-SGSN need to communicate with legacy SGSN via Gn/Gp interface to allow UE handover from 2G/2G to E-UTRAN access, and vice versa. 
         [0011]    The legacy SGSN, GGSN, and HLR need a solution to seamlessly migrate to the Evolved ARP concept to allow introducing the services which evolved ARP is required. Again, PDN-GW and MME need a solution to communicate with legacy SGSN when come to ARP handling. 
       SUMMARY 
       [0012]    The present invention related to a solution introducing optional Information Elements (IE) to carry Evolved ARP separately from the legacy ARP. New optional IEs are needed for both Gr interface and Gn/Gp interface. 
         [0013]    Furthermore, SGSN, and GGSN/PDN-GW are able to map between legacy ARP and Evolved ARP. 
         [0014]    The present is realized in a number of aspects in which a first is a method in an infrastructure node. The method is used for handling allocation and retention priority in a telecommunications network. The method comprises steps of obtaining a trigger event for changing status of a user equipment (UE) wirelessly attachable to the telecommunications network, receiving from a subscriber registration node information of subscribed allocation and retention priority (ARP) for the UE, the ARP information comprising a combination of legacy ARP and evolved ARP, including the legacy and evolved ARP information in a control message transmitted to a gateway node, obtaining from the gateway node information about an authorized ARP, and transmitting the authorized ARP information to a radio network connecting the UE without further validation against subscribed ARP from the subscriber registration node. 
         [0015]    The authorized ARP information may be transmitted in both an Evolved ARP information element and a Quality of Service Profile information element. 
         [0016]    The trigger event may be at least one of an activation of primary PDP context, an inter SGSN mobility procedure, such as a radio access technology change, i.e. IRAT, an inter SGSN Routing Area Update, and a Packet Switched, i.e. PS, handover. 
         [0017]    The infrastructure node may be one of SGSN or MME and the subscriber registration node may be one of HLR or HSS. 
         [0018]    The subscribed ARP information may be received in a map insert subscriber data procedure via a Gr interface between the subscriber registration node and a serving node. 
         [0019]    The method may be arranged so as to if the infrastructure node only receives legacy ARP from the subscriber registration node, further comprise a step of mapping the legacy ARP to evolved ARP before transmitting to the gateway node. The gateway node may be one of a PDN-GW with a Gn or Gp interface towards a SGSN or a GGSN without an EPC interface. 
         [0020]    Another aspect of the present invention is provided, an infrastructure node in a telecommunications network. The node may be configured to obtain a trigger event for changing status of a user equipment (UE) wirelessly attachable to the telecommunications network, receive from a subscriber registration node information of subscribed allocation and retention priority (ARP) for the UE, the ARP information comprising a combination of legacy ARP and evolved ARP, include the legacy and evolved ARP information in a control message transmitted to a gateway node, obtain from the gateway node information about an authorized ARP; and transmit the authorized ARP information to a radio network connecting the UE. 
         [0021]    The infrastructure node may be a Serving GPRS Support node (SGSN), and wherein the infrastructure node may further be configured to map legacy ARP to evolved ARP. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    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: 
           [0023]      FIG. 1  illustrates schematically a network system according to the present invention; 
           [0024]      FIG. 2  illustrates schematically a node according to the present invention; 
           [0025]      FIG. 3  illustrates schematically in a block diagram a method according to the present invention; and 
           [0026]      FIG. 4  illustrates schematically in a sequence diagram a method according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    In  FIG. 1 , reference numeral  100  generally depicts a telecommunications network according to the present invention. The network comprises a mobility handling node  103 , e.g. an SGSN, a packet data network gateway  104  (GGSN/PDN-GW), a subscription database  105 , e.g. a Home Location Register (HLR) or Home Subscriber Server (HSS), and a Policy and Charging Rules Function node  106  (PCRF). The mobility node is connected to a radio access network  102  which in turn connects a user equipment  101  (UE) using suitable wireless communication technology  109 . The SGSN is connected to the PDN-GW using a Gn/Gp interface  111  and to the HLR using a Gr interface  108 . 
         [0028]    Furthermore, the GGSN/PDN-GW is connected to the PCRF using a Gx interface  110 . It should be noted that the nodes in the network are physically interconnected using routers, switches, cabling, and other similar devices; however, these are not shown since they are not needed for the understanding of the present invention. 
         [0029]    The nodes  200  forming the network  100  all comprise at least one processing unit  201  as shown in  FIG. 2 . Furthermore, the nodes also comprise at least one memory unit  202  and at least one communication interface  203 . The processing unit may be any suitable type, such as for instance a microprocessor, digital signal processor (DSP), application specific integrated circuit (ASIC), or field programmable gate array (FPGA) configured to execute software or hardware instruction sets stored in the memory unit or stored in the processing unit. The memory unit may be of a volatile and/or non-volatile type and it provides a computer readable storage medium. The communication interface is advantageously a packet data interface, such as for instance of Ethernet type. 
         [0030]    When a change in session is performed the mobility management node obtains ARP information from the subscriber database. This ARP information is stored in the subscriber database and is related to the user as a subscribed ARP. 
         [0031]    The subscribed ARP is part of Subscribed QoS profile for a certain PDN connection which is stored in the subscriber database, e.g. the HLR, and is delivered to the mobility management node, e.g. SGSN, via Gr interface during UE attachment to the network. 
         [0032]    When UE activates a primary PDP context, the SGSN includes the requested ARP based on the subscribed ARP and its own admission and congestion control to PDN-GW/GGSN via Gn/Gp interface, where PDN-GW/GGSN may grant ARP based on the result either from interaction together with Policy and Charging Control function or/and its own admission and congestion control. 
         [0033]    The responded ARP from the PDN-GW/GGSN then becomes Authorized ARP (or negotiated) and is further transmitted to Radio network, i.e. RNC or BSS. 
         [0034]    This is illustrated in  FIG. 3  which shows steps of a method according to the present invention. First subscribed ARP information is obtained  301  from the HLR in the SGSN. The SGSN transmit  302  a request control message to the gateway comprising the ARP information. The SGSN receives  303  a response control message from the gateway comprising authorized ARP information. The SGSN forwards  304  the authorized ARP information to radio network. 
         [0035]    In the solution according to the present invention, optional information elements (IE) is introduced that carry the Evolved ARP information on both Gr and Gn interfaces. 
         [0036]    The same principle introduced by the present invention is also applied for PDN-GW and MME when come to inter RAT mobility cases,i.e. between 2G/3G Gn/Gp SGSN and MME. 
         [0037]      FIG. 4  shows how ARP is handled during attach and PDP context activation in the home PLMN, i.e. Gp interface is not depicted.  FIG. 4  is only an example use of the solution according to the present invention; an example for an initial attachment of a UE to the network. 
         [0038]    The UE sends  401  an attach request to the SGSN, via appropriate radio network nodes, which in turn sends  402  a message with an update of GPRS location to the HLR of the UE. The HLR responds  403  with an insert subscribe data message comprising subscribed ARP information to the SGSN. The SGSN then sends  404  an attach accept message back to the UE. 
         [0039]    The UE sends  405  a request for an activation of PDP context to the SGSN which in turn send  406  a create PDP context request to the PDN-GW/GGSN comprising requested ARP from the subscribed ARP. The PDN-GW/GGSN will communicate  407  and  408  with the PCRF for credit control and other authorizations. The request comprises the requested ARP and the answer response comprises authorized ARP from the PCRF. 
         [0040]    The PDN-GW/GGSN will respond  408  to the SGSN with a create PDP context response comprising authorized ARP(s). The SGSN will in turn send  409  an activate PDP context accept message. 
         [0041]    It should be noted that in the above examples the term “PDN-GW/GGSN” is meant as a PDN-GW implementing Gn/Gp interface to communicate with a legacy SGSN or a legacy GGSN without EPC interfaces. 
         [0042]    It should be appreciated that not all signaling is shown in  FIG. 4 , but only the signaling relevant for illustrating an example use of the present invention. 
         [0043]    There are several different situations that each are handled differently, below some situations are discussed and their respective solutions. 
         [0044]    1. If the HLR supports Evolved ARP, both legacy subscribed ARP and new Evolved subscribed ARP are delivered from HLR to SGSN through MAP_INSERT_SUBSCRIBER_DATA procedure via Gr interface when UE attaches in 2G/3G network, otherwise only legacy subscribed ARP is sent. 
         [0045]    2. An Evolved ARP supported SGSN includes the subscribed Evolved ARP and legacy ARP in a GTP message “Create PDP context request” using GTP IE Quality of Service profile and new optional IE Evolved ARP to the PDN-GW/GGSN if the UE try to activate PDP context. 
         [0046]    3. If an Evolved ARP supported SGSN receives only legacy ARP from HLR, the SGSN maps it to Evolved ARP based on Annex E in 3GPP 23.401, and include the subscribed Evolved ARP and legacy ARP in the GTP message “create PDP context request” using GTP IE Quality of Service profile and new optional IE Evolved ARP to the PDN-GW/GGSN. 
         [0047]    4. If the SGSN does not recognize the Evolved ARP received from HLR, it include only the legacy ARP in the GTP message “create PDP context request” using GTP IE Quality of Service profile to the PDN-GW/GGSN. 
         [0048]    5. If an Evolved ARP supported PDN-GW/GGSN receives only legacy ARP, it maps it to Evolved ARP based on Annex E in 3GPP 23.401, and send it to PCRF to ask for authorization. When the PDN-GW/GGSN get the authorized Evolved ARP via Gx interface from PCRF, it maps it back to legacy ARP and then include it only in the GTP message “Create PDP context response” back to SGSN. 
         [0049]    6. If an Evolved ARP supported PDN-GW/GGSN receives both the Evolved ARP and legacy ARP in the GTP message “Create PDP context request”, it uses Evolved ARP to ask for authorization towards PCRF via Gx interface. When the PDN-GW/GGSN get the authorized Evolved ARP, it send only the Evolved ARP in the GTP message “Create PDP context Response” back to SGSN. 
         [0050]    7. If a legacy GGSN does not recognize the Evolved ARP received from SGSN, it grants the requested ARP based on its own admission and congestion control. 
         [0051]    The present invention provides a solution for seamless migration from legacy ARP to the Evolved ARP concept to allow introducing the services which Evolved ARP is required, and the same time fully backward compatible. 
         [0052]    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. 
         [0053]    The above mentioned and described embodiments are only given as examples and  20  should not be limiting to the present invention. Other solutions, uses, objectives, and functions within the scope of the invention as claimed in the below described patent claims should be apparent for the person skilled in the art. 
       Abbreviations 
       [0000]    
       
         GTP GPRS Tunnelling protocol 
         ARP Allocation and Retention Priority 
         SGSN Serving GPRS support node 
         GGSN Gateway GPRS support node 
         RNC Radio network controller 
         UE User equipment 
         UMTS Universal Mobile telecommunications system 
         E-UTRAN Evolved UTRAN 
         UTRAN Universal terrestrial radio access network 
         GBR Guaranteed bit rate 
         EPS Evolved packet system 
         EPC Evolved packet core 
         eNB evolved Node B 
         PDN Packet data network 
         PDN-GW Packet data network gateway 
         BSS Base station subsystem 
         PDP Packet data protocol 
         MME Mobility management entity 
         QoS Quality of Service 
         IE Information element 
         PCRF Policy and charging rules function 
         RAT Radio access technology 
         HLR Home location register 
         BSC Base station controller 
       
     
       Definitions 
       [0078]    Gi Reference point between a GGSN and a packet data network. 
         [0079]    Gn Interface between a SGSN within the same or different PLMNs or between SGSN and a GGSN within the same PLMN. 
         [0080]    Gp Interface between a SGSN and a Pdn-GW/GGSN in different PLMNs. The Gp interface allows support of GPRS network services across areas served by the co-operating GPRS PLMNs. 
         [0081]    Gr Interface between an SGSN and an HLR. 
         [0082]    Gx It provides transfer of (QoS) policy and charging rules from PCRF to Policy and charging enforcement function 8PCEF) in the PDN-GW.