Abstract:
A method for a cellular communications system ( 100 ) with a user (UE,  110 ) and a hierarchy of nodes between a UE ( 110 ) and an external network ( 150 ). The hierarchy comprises at least first ( 125 ) and second ( 130 ) nodes, and there can be a plurality of connections between the UE ( 110 ) and the network ( 150 ) via data channels ( 160 ) between the nodes, and plurality of data containers ( 170 ) with data regarding the data channels. A connection between a UE ( 110 ) and the external network ( 150 ) can be inactivated whilst the corresponding data container ( 170 ) is preserved, and an inactivated connection can be reactivated by the external network ( 150 ). When a connection is to be reactivated, the second node ( 130 ) utilizes information from the external network ( 150 ) in order to reactivate the data channel or channels which is/are concerned and which have had their data containers ( 170 ) preserved.

Description:
TECHNICAL FIELD 
       [0001]    The present invention discloses a method for use in a wireless cellular communications system. The system in which the invention can be applied can comprise at least one user, and has a hierarchy of nodes between a user and an external network which the user wishes to communicate with. 
         [0002]    In the node hierarchy, there is at least a first and a second node, and in the system there can be a number of connections between the user and the external network via data channels between the first and second nodes. In the system, there is also a plurality of data containers which contain data regarding the data channels, and a connection between a user and the external network can be inactivated whilst the data container for the corresponding data channel is preserved. 
         [0003]    An inactivated data channel can be reactivated by a request from the external network to said second node. 
       BACKGROUND 
       [0004]    In wireless communication systems such as 3G systems, there can be a multitude of connections established between a user equipment, UE, such as a mobile telephone or computer, and an external network which the system connects the UE to, such as, for example, the Internet or a telephony or data network. For example, one such connection can be used for surfing the Internet, while another connection is used for watching video and a third connection is used for sending and receiving electronic mail. 
         [0005]    In known systems, a connection will comprise a data channel between two nodes in the system, as well as a data channel between one of those nodes and the UE. 
         [0006]    The connections between the UE and the external network can be inactivated by the system, for example if the UE is inactive longer than a predefined length of time. A connection which has been inactivated can be reactivated, for example by a request from the external network. 
         [0007]    When a connection between a UE and an external network is initially activated, the data channels mentioned are established, together with data containers which contain data regarding the data channels between said two nodes. When a connection is inactivated, the data channels are released, but residues of the connection still remain in the system, such as, for example, the data containers. 
         [0008]    When the external network wishes to activate an inactivated connection, the system will reactivate the data channels. However, in a situation where more than one connection has been inactivated, all of the data channels will be activated, which is undesirable with regard to, for example, resource utilisation both in the UE and in the system as such. 
       SUMMARY 
       [0009]    As described above, there is thus a need for a solution in a wireless cellular communications system which will provide a more efficient resource utilization when a connection between a UE and an external network is reactivated, particularly in the case when more than one connection has been inactivated and it is desired to reactivate only a subset of those connections, for example one particular connection. 
         [0010]    This need is addressed by the present invention in that it provides a method for use in a wireless cellular communications system, which system can comprise at least one user, UE, and which comprises a hierarchy of nodes between a UE and an external network which the UE wishes to communicate with. 
         [0011]    The hierarchy comprises at least a first and a second node, and in the system there can be a first plurality of connections between the UE and the external network via data channels between said first and second nodes, and a second plurality of data containers which contain data regarding the data channels. 
         [0012]    A connection between a UE and the external network can be inactivated in the system whilst the corresponding data container is preserved, and an inactivated connection can be reactivated by a request from the external network to the second node. 
         [0013]    According to the method of the invention, when a connection is to be reactivated, the second node utilizes information from the external network in order to reactivate the data channel or channels which is/are concerned and which have had their data containers preserved. 
         [0014]    Thus, by means of the method of the invention, a more efficient utilization of the system is achieved, since only those data channels which are actually needed are reactivated. 
         [0015]    Suitably but not necessarily, the data containers are located in the second node. 
         [0016]    In a preferred embodiment of the invention, an inactivated connection is reactivated by a request from the external network, which request comprises a paging of the UE in the system, following which the UE signals to the system, as a consequence of which said data channel/s is/are reactivated. 
         [0017]    The invention is also directed towards a node with functionality according to the method. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The invention will be described in more detail in the following, with reference to the appended drawings, in which 
           [0019]      FIG. 1  shows a schematic overview of a system in which the invention may be applied, and 
           [0020]      FIG. 2  shows a sequence diagram which may be used in the system of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION  
       [0021]    The invention will be described in the following with reference to a 3G system of the WCDMA type, but it should be pointed out that this is by way of example only, and is in no way limiting regarding the scope of the invention. 
         [0022]      FIG. 1  shows a schematic overview of a system  100  in which the invention may be applied. The system  100  is thus a 3G cellular wireless telephony system, and can comprise a number of users, referred to from now on as User Equipments, UE, and shown as  110  in  FIG. 1 . In some applications, the users are referred to as Mobile Stations, MS, so the term UE should not be construed as limiting the scope of the invention in any way. 
         [0023]    The system  100  as such is hierarchical, i.e. the system comprises a number of nodes on different levels above the UE  110 . In the system  100  which is shown as an example, the node closest to the UE is the so called Node B,  120 , which in some systems is also referred to as the Radio Base Station or RBS. 
         [0024]    The nodes above the Node B are, in rising order, the Radio Network Controller, RNC,  125 , the Serving GPRS Support Node, SGSN,  130 , and the Gateway GPRS Support Node, GGSN,  140 . 
         [0025]    The functions and roles of the RNC-SGSN-GGSN are well known to those skilled in the field, and will thus not be described in more detail here. 
         [0026]    Also shown in  FIG. 1  is an external network  150 , which may be more or less any kind of external network to which the system  100  can connect the UE  110 . As an example, the external network  150  is shown in  FIG. 1  as the Internet or an Intranet. 
         [0027]    In a system in which the invention may be applied, the UE can establish a number of so called connections to the external network  150  by means of the system  100 . Each connection may serve a different purpose compared to the other connections which the UE has established, and examples of such different purposes which can be mentioned are sending and receiving electronic messages, surfing on the external network, watching video, etc. 
         [0028]    In order to save resources, a connection between the UE and the external system  150  which has not been used by the UE  110  for a specified length of time may be deactivated automatically by the system. It is when such a deactivated connection is to be reactivated that the invention may be applied. 
         [0029]    Before the invention is described in detail, some more details in the system will be described: for each connection between the UE  110  and the external system  150 , the system establishes a data channel, referred to as a Radio Access Bearer, RAB,  160 , between the RNC  125  and the SGSN  130 . The Node B  120  connects the RAB  160  to the UE  110  via a data channel referred to as the RRC, Radio Resource Control,  190 . 
         [0030]    The RAB  160  is connected to the external system  150  through the SGSN and GGSN via a number of so called data tunnels  180 . Also, as shown in  FIG. 1 , the system establishes so called Packet Data Control Contexts, PDP Contexts  170 , which can be seen as data containers which contain data about each RAB. An example of data about a RAB which is held by its PDP Context is its Quality of Service, QoS, which contains the Traffic Class, the maximum bit rate (both in the uplink and downlink directions), the guaranteed bit rate, transfer delay, traffic handling priority, and the delivery order. 
         [0031]    When a connection between the UE  110  and the external system  150  is deactivated due to inactivity in the UE, the RRC  190  and the RAB  160  for that connection are released, i.e. disconnected. However, the corresponding PDP Context  170  and the data tunnels  180  are preserved. 
         [0032]    It can also be mentioned here that the GGSN also maintains a data context for the corresponding data connection to the SGSN, said data context also being preserved when the RRC and the RAB are released. 
         [0033]    When it is desired to reactivate a connection which has been inactivated, the procedure shown in  FIG. 2  is followed.  FIG. 2  shows, apart from that which has been described above, the Home Location Register, HLR, which is a well known function in systems of the 3G kind, and which will thus not be described in more detail here. 
         [0034]    In order not to obscure  FIG. 2 , the steps in the sequence of  FIG. 2  are only shown with numerals ( 1 - 8 ) and arrows in the diagram of  FIG. 2 , said numerals being explained below. Steps which are not always carried out, i.e. which may be optional, are shown with dashed lines. 
         [0035]      1 ) The SGSN receives a downlink PDP PDU (Protocol Data Unit) from the GGSN for a UE which is in an idle state, in the system of the example the so called PMM-IDLE state. 
         [0036]      2 ) The SGSN sends a Paging message to the RNC. The RNC pages the UE by sending a Paging message to the UE. 
         [0037]      3 ) The UE establishes an RRC connection if none exists. 
         [0038]      4 ) The UE sends a Service Request message to the SGSN. The SGSN knows whether or not the downlink packet requires RAB establishment (e.g. downlink PDU) or not (e.g. Request PDP Context Activation or MT SMS). 
         [0039]      5 ) The SGSN may perform a security mode procedure. 
         [0040]      6 ) If resources for the PDP contexts are re-established, the SGSN sends a Radio Access Bearer Assignment Request message to the RNC. The RNC sends a Radio Bearer Setup to the UE. The UE responds by returning a Radio Bearer Setup Complete message to the RNC. 
         [0041]    The RNC sends a Radio Access Bearer Assignment Response message to the SGSN in order to indicate that tunnels are established on the Iu interface, and Radio Access Bearers are established between the RNC and the UE. 
         [0042]      7 ) For each RAB re-established with a modified QoS (Quality of Service) profile, the SGSN initiates a PDP Context Modification procedure to inform the UE and the GGSN of the new QoS profile for the corresponding PDP context. 
         [0043]      8 ) The SGSN sends the downlink packet, the PDU. 
         [0044]    In the scenario above, in step  6  of known systems, the SGSN  130  re-establishes or reactivates the RABs  160 , of all of the inactivated connections between the UE  110  and the external system  150 , and the corresponding RRCs  190  are reestablished by the RNC  125 . However, this may not be necessary, since the event that led to the paging of the UE  110  by the external system  150  may only be relevant for one of the RABs  160 , i.e. one of the inactivated connections. This leads to unnecessary utilization of resources in the UE  110  and in the system  150  as a whole. 
         [0045]    According to the invention, the SGSN  130  uses the fact that it knows which RAB  160  and which PDP context that is affected by the event behind the paging request in order to only activate the RAB  160  which is concerned. 
         [0046]    Thus, by means of the invention, a more efficient utilization of system resources in the system  100  is achieved. 
         [0047]    The invention uses the fact that the SGSN  130  gets the “downlink PDU” in step  1  of  FIG. 2 , and as described above, on a tunnel  180  which is coupled to a specific PDP Context  170 . By virtue of this fact, the SGSN knows exactly which RAB to reactivate, since there is a one-to-one relationship between each RAB  160  and each PDP Context  170 . 
         [0048]    In the system  100  shown as an example above, the data containers  170  are located in the SGSN  130 . Naturally, the invention may be applied to systems in which the data containers are located in another node in the system. 
         [0049]    Also, the event that leads to the reactivation of the connection may be another event than a downlink PDU from an external system, this should also be seen merely as an example. 
         [0050]    The invention is not limited to the examples described above and shown in the appended drawings, but may be freely varied within the scope of the appended claims. 
         [0051]    As an example, the examples shown above have shown what happens according to the invention when it is desired to reactivate one connection with one data channel. Naturally, the invention can be applied when reactivating any number of connections with any number of data channels.