Patent Publication Number: US-11039500-B2

Title: Resource allocation for group communication in a network

Description:
TECHNICAL FIELD 
     Embodiments presented herein relate to methods, a server node, a core network node, computer programs, and a computer program product for resource allocation for group communication in a network. 
     BACKGROUND 
     In communications networks, there may be a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communications network is deployed. 
     For example, so-called Mission Critical (MC) communication services (hereinafter MC service for short) could be essential for the work performed by public safety users, e.g. ambulance services, police force and fire brigade. MC services require preferential handling compared to normal telecommunication services, including prioritized handling of MC calls for emergency and imminent threats. One commonly used communication mechanism for public safety users is Group Communication (GC). Group Communication generally requires that the same information is delivered to multiple users. One type of Group Communication is Push to Talk (PTT) services. 
     A PTT call typically starts with that one user requests the right to transmit and a PTT control node grants this request. The media of the call (such as audio, video, text, images, etc.) is then transmitted from one user to multiple PTT users. These PTT users may be located at different locations. If many users are located within the same area, multicast or broadcast based transmission using e.g. Multicast-Broadcast Multimedia Services (MBMS) in a third generation partnership project (3GPP) network enabled for MBMS is efficient. MBMS is a unidirectional transmission technology. One advantage of using MBMS is that the number of users does not impact the performance that much. In a PTT call over MBMS, voice data is transmitted to, and reached by, all users at the same time, which also means that all users get the same mouth-to-ear delay experience. 
     In a Group Communication (GC) service such as PTT, one commonly used protocol is the Session Initiation Protocol (SIP). The SIP protocol initiates and establishes communication sessions used by the service. During the SIP session establishment, session parameters e.g. media parameters, codecs, Internet Protocol (IP) address and port numbers, are negotiated. In a 3GPP based telecommunications system, the network resources to be used for the service are requested at the SIP session establishment. 
     The SIP protocol is transferred with the Transmission Control Protocol (TCP) and requires bi-directional transmission, which means that unicast transmission must be used. Thus, MBMS cannot be used for session establishment but only after session establishment. 
     There are strict and challenging performance requirements related to group communication, and specifically to PTT services. One example of such a key performance indicator (KPI) is the mouth-to-ear delay requirement. This KPI is usually defined as the time from that a user&#39;s voice is recorded by the microphone of the transmitting device to the time when the same voice is played out in the speaker of the receiving devices. 
     To establish a SIP session for a PTT group call with many users is a time consuming procedure. The consequence of this is that it is difficult to reach the KPIs for call setup and mouth-to-ear. Hence, there is still a need for an improved session establishment procedure for group communication sessions to be able to meet the performance requirements for group communication, such as PTT. 
     SUMMARY 
     An object of embodiments herein is to provide mechanisms for efficient resource allocation for group communication in a network. 
     According to a first aspect there is presented a method for resource allocation for group communication in a network. The method is performed by a server node of the group communication system. The method comprises receiving a first request from a client node for the client node to affiliate with a group of client nodes in order for the client node to join a group communication session of the group communication system. The method comprises requesting, from a core network node and in response to the first request, a first allocation of network resources to be used by the client node for transmission control of the group communication session. The method comprises receiving a second request for a group call from the client node. The method comprises requesting, from the core network node and upon reception of the second request, a second allocation of network resources to be used by the client node for media transmission in the group call. 
     According to a second aspect there is presented a server node for resource allocation for group communication in a network. The server node comprises processing circuitry. The processing circuitry is configured to cause the server node to receive a first request from a client node for the client node to affiliate with a group of client nodes in order for the client node to join a group communication session of the group communication system. The processing circuitry is configured to cause the server node to request, from a core network node and in response to the first request, a first allocation of network resources to be used by the client node for transmission control of the group communication session. The processing circuitry is configured to cause the server node to receive a second request for a group call from the client node. The processing circuitry is configured to cause the server node to request, from the core network node and upon reception of the second request, a second allocation of network resources to be used by the client node for media transmission in the group call. 
     According to a third aspect there is presented a server node for resource allocation for group communication in a network. The server node comprises processing circuitry and a storage medium. The storage medium stores instructions that, when executed by the processing circuitry, cause the server node to perform operations, or steps. The operations, or steps, cause the server node to receive a first request from a client node for the client node to affiliate with a group of client nodes in order for the client node to join a group communication session of the group communication system. The operations, or steps, cause the server node to request, from a core network node and in response to the first request, a first allocation of network resources to be used by the client node for transmission control of the group communication session. The operations, or steps, cause the server node to receive a second request for a group call from the client node. The operations, or steps, cause the server node to request, from the core network node and upon reception of the second request, a second allocation of network resources to be used by the client node for media transmission in the group call. 
     According to a fourth aspect there is presented a server node for resource allocation for group communication in a network. The server node comprises a receive module configured to receive a first request from a client node for the client node to affiliate with a group of client nodes in order for the client node to join a group communication session of the group communication system. The server node comprises a request module configured to request, from a core network node and in response to the first request, a first allocation of network resources to be used by the client node for transmission control of the group communication session. The server node comprises a receive module configured to receive a second request for a group call from the client node. The server node comprises a request module configured to request, from the core network node and upon reception of the second request, a second allocation of network resources to be used by the client node for media transmission in the group call. 
     According to a fifth aspect there is presented a computer program for resource allocation for group communication in a network. The computer program comprises computer program code which, when run on processing circuitry of a server node, causes the server node to perform a method according to the first aspect. 
     According to a sixth aspect there is presented a method for resource allocation for group communication in a network. The method is performed by a core network node. The method comprises receiving, from a server node of a group communication system, a first request for first network resources to be used by a client node of a group communication session of the group communication for transmission control of the group communication session. The method comprises requesting a radio access network of the client node to make the first network resources available to the client node. The method comprises receiving, from the server node, a second request for second network resources to be used by the client node for media transmission in the group call. The method comprises requesting the radio access network of the client node to make the second network resources available to the client node. The first request and the second request are received during one and the same SIP session or SAP session. 
     According to a seventh aspect there is presented a core network node for resource allocation for group communication in a network. The core network node comprises processing circuitry. The processing circuitry is configured to cause the core network node to receive, from a server node of a group communication system, a first request for first network resources to be used by a client node of a group communication session of the group communication for transmission control of the group communication session. The processing circuitry is configured to cause the core network node to request a radio access network of the client node to make the first network resources available to the client node. The processing circuitry is configured to cause the core network node to receive, from the server node, a second request for second network resources to be used by the client node for media transmission in the group call. The processing circuitry is configured to cause the core network node to request the radio access network of the client node to make the second network resources available to the client node. The first request and the second request are received during one and the same SIP session or SAP session. 
     According to an eighth aspect there is presented a core network node for resource allocation for group communication in a network. The core network node comprises processing circuitry and a storage medium. The storage medium stores instructions that, when executed by the processing circuitry, cause the core network node to perform operations, or steps. The operations, or steps, cause the core network node to receive, from a server node of a group communication system, a first request for first network resources to be used by a client node of a group communication session of the group communication system for transmission control of the group communication session. The operations, or steps, cause the core network node to request a radio access network of the client node to make the first network resources available to the client node. The operations, or steps, cause the core network node to receive, from the server node, a second request for second network resources to be used by the client node for media transmission in the group call. The operations, or steps, cause the core network node to request the radio access network of the client node to make the second network resources available to the client node. The first request and the second request are received during one and the same SIP session or SAP session. 
     According to a ninth aspect there is presented a core network node for resource allocation for group communication in a network. The core network node comprises a receive module configured to receive, from a server node of the group communication system, a first request for first network resources to be used by a client node of a group communication session of the group communication system for transmission control of the group communication session. The core network node comprises a request module configured to request a radio access network of the client node to make the first network resources available to the client node. The core network node comprises a receive module configured to receive, from the server node, a second request for second network resources to be used by the client node for media transmission in the group call. The core network node comprises a request module configured to request the radio access network of the client node to make the second network resources available to the client node. The first request and the second request are received during one and the same SIP session or SAP session. 
     According to a tenth aspect there is presented a computer program for resource allocation for group communication in a network, the computer program comprising computer program code which, when run on processing circuitry of a core network node, causes the core network node to perform a method according to the sixth aspect. 
     According to an eleventh aspect there is presented a computer program product comprising a computer program according to at least one of the fifth aspect and the tenth aspect and a computer readable storage medium on which the computer program is stored. The computer readable storage medium could be a non-transitory computer readable storage medium. 
     Advantageously these methods, these server nodes, these core network nodes, and these computer programs provide efficient resource allocation for group communication in a network. This in turn provides an efficient session establishment procedure for group communication sessions that meets the performance requirements for group communication system, such as PTT. 
     Advantageously these methods, these server nodes, these core network nodes, and these computer programs enable network resources for media transmission are only allocated when needed, i.e. when the group call starts. This allows SIP sessions to be established long time before the group call starts, which could be beneficial from a performance perspective. 
     Advantageously these methods, these server nodes, these core network nodes, and these computer programs enable mouth-to-ear delay requirements to be met also for group calls with many users using unicast (bi-directional) transmission. 
     It is to be noted that any feature of the first, second, third, fourth, fifth, sixth seventh, eight, ninth, tenth and eleventh aspects may be applied to any other aspect, wherever appropriate. Likewise, any advantage of the first aspect may equally apply to the second, third, fourth, fifth, sixth, seventh, eight, ninth, tenth, and/or eleventh aspect, respectively, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings. 
     Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the element, apparatus, component, means, module, step, etc.” are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic diagram illustrating a communications network according to embodiments; 
         FIG. 2  is a schematic illustration of a SIP session for a group call according to state of the art; 
         FIGS. 3 and 4  are flowcharts of methods according to embodiments; 
         FIG. 5  is a schematic illustration of a SIP session for a group call according to an embodiment; 
         FIG. 6  is a signalling diagram according to an embodiment; 
         FIG. 7  is a schematic diagram showing functional units of a server node according to an embodiment; 
         FIG. 8  is a schematic diagram showing functional modules of a server node according to an embodiment; 
         FIG. 9  is a schematic diagram showing functional units of a core network node according to an embodiment; 
         FIG. 10  is a schematic diagram showing functional modules of a core network node according to an embodiment; and 
         FIG. 11  shows one example of a computer program product comprising computer readable means according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional. 
       FIG. 1  is a schematic diagram illustrating a communications network  100  where embodiments presented herein can be applied. The communications network  100  may be regarded as a wireless communications network. The wireless communications network provides services to client nodes  160   a ,  160   b ,  160   c . Each client node  160   a ,  160   b ,  160   c  may be provided in, or installed on, a respective wireless device  150   a ,  150   b ,  150   c.    
     The communications network  100  comprises a radio access network  120 , a core network  130  comprising a core network node  300 , and a service network  140  comprising a server node  200 . The server node  200  could implement the functionality of a group communication server node (GC server node) or an MC service server. 
     The radio access network  120  is operatively connected to the core network  130  which in turn is operatively connected to the service network  140 . Radio access network nodes  110  in the radio access network  120  thereby enable the wireless devices  150   a ,  150   b ,  150   c , and hence the client nodes  160   a ,  160   b ,  160   c , to access services and exchange data as provided by the service network  140 . Particularly, the client nodes  160   a ,  160   b ,  160   c  are thereby enabled to communicate with the server node  200 . 
     Examples of wireless devices  150   a ,  150   b ,  150   c  include, but are not limited to, mobile stations, mobile phones, handsets, wireless local loop phones, user equipment (UE), smartphones, laptop computers, and tablet computers. Examples of radio access network nodes  110  include, but are not limited to, radio base stations, base transceiver stations, node Bs, evolved node Bs, gigabit node Bs, and access points. As the skilled person understands, the communications network  100  may comprise a plurality of radio access network nodes  110 , each providing network access to a plurality of wireless devices  150   a ,  150   b ,  150   c . The herein disclosed embodiments are not limited to any particular number of radio access network nodes  110 , client nodes  160   a ,  160   b ,  160   c , or wireless devices  150   a ,  150   b ,  150   c.    
     The nodes indicated herein may be seen as functions, where each function may be implemented in one or more physical entities. Further, a step, action, or similar that is performed by a client node  160   a ,  160   b ,  160   c  is, in some aspects, also performed by the wireless device  150   a ,  150   b ,  150   c  in which the client node  160   a ,  160   b ,  160   c  is provided. 
     As disclosed above, setting up SIP sessions and allocating resources takes too long time in group communications, such as group calls, when many client nodes  160   a ,  160   b ,  160   c  are involved. The KPIs for group communication is thus challenging to meet with large groups of client nodes  160   a ,  160   b ,  160   c.    
     SIP sessions could be pre-established prior a group call. However, when pre-establishing SIP sessions in a 3GPP based telecommunications network it will also require that the network resources are allocated at the same time, which might result in a waste of network resources if the group call does not start soon after the SIP session has been established. 
       FIG. 2  schematically illustrates a SIP session for a group call. “DT” is short for data transmission. As illustrated in  FIG. 2 , a client node affiliates with a group in order to participate in the group communication (which means that the client node is allowed to transmit or receive data in the group). All network resources required for the group call are allocated when the group call starts (at the group call setup) and released at group call end. 
     To start a group call using the SIP protocol is time consuming. For large groups of client nodes it is challenging to reach acceptable KPIs if the group communication session is started at the group call setup. The group communication session may also be started at the group affiliation. However, this gives the disadvantage that the network resources are allocated even if there is not any ongoing group call. 
     The embodiments disclosed herein thus relate to mechanisms for resource allocation for group communication in a network  100 . In order to obtain such mechanisms there is provided a server node  200 , a method performed by the server node  200 , a computer program product comprising code, for example in the form of a computer program, that when run on processing circuitry of the server node  200 , causes the server node  200  to perform the method. In order to obtain such mechanisms there is further provided a core network node  300 , a method performed by the core network node  300 , and a computer program product comprising code, for example in the form of a computer program, that when run on processing circuitry of the core network node  300 , causes the core network node  300  to perform the method. 
       FIG. 3  is a flowchart illustrating embodiments of methods for resource allocation for group communication in a network  100  as performed by the server node  200 .  FIG. 4  is a flowchart illustrating embodiments of methods for resource allocation for group communication in a network  100  as performed by the core network node  300 . The methods are advantageously provided as computer programs  1120   a ,  1120   b.    
     Reference is now made to  FIG. 3  illustrating a method for resource allocation for group communication in a network  100  as performed by the server node  200  of the group communication system according to an embodiment. 
     It is assumed that client node  160   a  wishes to affiliate with a group of client nodes and therefore sends a request relating thereto to the server node  200 . The server node  200  is assumed to receive this request. Particularly, the server node  200  is configured to perform step S 102 : 
     S 102 : The server node  200  receives a first request from the client node  160   a . The first request is for the client node  160   a  to affiliate with a group of client nodes  160   b ,  160   c . This is in order for the client node  160   a  to join a group communication session of the group communication system. 
     The server node  200  responds to the first request by requesting network resources to be used by the client node  160   a . However, in order to save network resources, network resources for media transmission are not requested at this time. Particularly, the server node  200  is configured to perform step S 104 : 
     S 104 : The server node  200  requests, from the core network node  300  and in response to the first request, a first allocation of network resources. These network resources are to be used by the client node  160   a  for transmission control of the group communication session. 
     The request in step S 104  is thus made without requesting any network resources to be used by the client node  160   a  for media transmission in the group communication session. Thus, in some aspects only network resources to be used for transmission control of the group communication session are requested. 
     It is assumed then that client node  160   a  intends to make a group call in the group communication session and therefore sends a request relating thereto to the server node  200 . The server node  200  is assumed to receive this request. Particularly, the server node  200  is configured to perform step S 108 : 
     S 108 : The server node  200  receives a second request from the client node  160   a . This second request is for a group call. The group call is thus to be made by the client node  160   a.    
     Since network resources for media transmission were not requested in step S 104  the server node  200  responds to the second request by, in turn, requesting further network resources to be used by the client node  160   a . Particularly, the server node  200  is configured to perform step S 110   a:    
     S 110   a : The server node  200  requests, from the core network node  300  and upon reception of the second request, a second allocation of network resources. These network resources are to be used by the client node  160   a  for media transmission in the group call. 
     The server node  200  thus provides separate requests for the network resources to be used by the client node  160   a  for transmission control of the group communication session and for the network resources to be used by the client node  160   a  for media transmission in the group call. The request for the network resources to be used by the client node  160   a  for transmission control of the group communication session is made upon receiving a request for the client node  160   a  to affiliate with a group of client nodes  160   b ,  160   c  whereas the request for the network resources to be used by the client node  160   a  for media transmission in the group call is delayed until receiving a request from the client node  160   a  for a group call. 
     Advantageously the method of steps S 102 , S 104 , S 108 , S 110   a  provides efficient resource allocation for group communication in the network  100 . This in turn provides an efficient session establishment procedure for group communication sessions that meets the performance requirements for group communication, such as PTT. 
     Advantageously the method of steps S 102 , S 104 , S 108 , S 110   a  enables network resources for media transmission only to be allocated when needed, i.e. when the group call starts. This allows SIP sessions or SAP sessions to be established long time before the group call starts, which could be beneficial from a performance perspective. 
     Advantageously the method of steps S 102 , S 104 , S 108 , S 110   a  enables mouth-to-ear delay requirements to be met also for group calls with many users using unicast (bi-directional) transmission. 
     Embodiments relating to further details of resource allocation for group communication in a network  100  as performed by the server node  200  will now be disclosed. 
     In some aspects the network resources requested in step S 104  and step S 110   a  are to be used for the same SIP session or Session Announcement Protocol (SAP) session. Particularly, according to an embodiment the network resources to be used by the client node  160   a  for transmission control of the group communication session and the network resources to be used by the client node  160   a  for media transmission in the group call are to be used in one and the same SIP session or SAP session. 
     In some aspects a new SIP session or SAP session is set up in response to the group affiliation in step S 102 . In particular, according to an embodiment the first request causes establishment of the SIP session or SAP session between the client node  160   a  and the server node  200 . 
     In other aspects the SIP session or SAP session is ongoing. In particular, according to an embodiment the SIP session or SAP session is ongoing when the first request is received. The first request then causes the client node  160   a  to affiliate to the group of client nodes  160   b ,  160   c  in the SIP session or SAP session. 
     There could be different purposes pf the transmission control. In some aspects the transmission control is for a PTT service in the group communication session. Particularly, according to an embodiment the transmission control comprises floor control in a PTT call of the group communication session. 
     There could be different types of requests made in step S 104  in order to specify that the network resources are to be used for transmission control. According to some aspects the server node  200  specifies the media type for the network resources as control. Particularly, according to an embodiment, requesting the first allocation involves the server node  200  to transmit a message indicating media type as control to the core network node  300 . 
     In some aspects the group communication session is established once having requested (and obtained) the first allocation of network resources in step S 104 . Hence, according to an embodiment the server node  200  is configured to perform (optional) step S 106 : 
     S 106 : The server node  200  establishes the group communication session with the client node  160   a . The group communication session is established when having requested the first allocation (as in step S 104 ) but before having requested the second allocation (as in step S 108 ). This enables the client node  160   a  to join the group communication session. 
     In some aspects the client node  160   a  uses the first allocated network resources when making the second request. Thus, according to an embodiment the second request is transmitted by the client node  160   a  using network resources according to the first allocation. 
     In some aspects the client node  160   a  in the second request requests the right to transmit media in the group call (where the client node  160   a  thus requests floor control). Particularly, according to an embodiment the second request comprises a request for the client node  160   a  to transmit media in the group call. 
     There could be different types of requests made in step S 110   a  in order to specify that the network resources are to be used for media transmission. According to some aspects the server node  200  specifies the media type for the network resources as audio or video. Particularly, according to an embodiment, requesting the second allocation involves the server node  200  to transmit a message indicating media type as audio or video to the core network node  300 . 
     In some aspects at least one further client node  160   b ,  160   c  has also affiliated with a group of client nodes and have had network resources allocated to be used by the further client nodes  160   b ,  160   c  for transmission control of the group communication session. Thus steps S 102 , S 104 , S 108  (and optionally, step S 106 ) have also been performed for these further client nodes  160   b ,  160   c . Therefore, network resources to be used by these further client nodes  160   b ,  160   c  for media transmission in the group call could also be requested when receiving the request in step S 108  for a group call from the client node  160   a . Particularly, according to an embodiment the server node  200  is configured to perform (optional) step S 110   b:    
     S 110   b : The server node  200  requests, from the core network node  300  and upon reception of the second request, a respective second allocation of network resources. These network resources are to be used by each client node  160   b ,  160   c  in the group of client nodes for media transmission in the group call. 
     If MBMS is used there is no need for network resource allocation for client nodes  160   b  and  160   c  in the uplink. Hence, step S 110   b  is not required for the client nodes  160   b  and  160   c  to be able to receive media transmission when using MBMS. That is, according to an embodiment the media transmission in downlink is using MBMS bearers, and only uplink network resources to be used by each client node  160   b ,  160   c  are requested in step S 110   b.    
     As disclosed above, the second request received in step S 108  is for a group call where the group call is to be made by the client node  160   a . In some aspects this marks the start of the group call (once the network resources requested in step S 110   a  have been granted). Particularly, according to an embodiment the server node  200  is configured to perform (optional) step S 112 : 
     S 112 : The server node  200  indicates, to all client nodes  160   a ,  160   b ,  160   c , start of the group call when having requested the second allocation. 
     Once the group call has been started any of the client nodes  160   a ,  160   b ,  160   c  could transmit media in the group call. In some aspects the client node  160   a  has requested floor control and thus intends to transmit media. Particularly, according to an embodiment the server node  200  is configured to perform (optional) step S 114 : 
     S 114 : The server node  200  receives media transmission for the group call from the client node  160   a.    
     The media transmission is transmitted by the client node  160   a  using network resources according to the second allocation. The server node  200  then forwards this media to the remaining client nodes  160   b ,  160   c  in the group call. Particularly, according to an embodiment the server node  200  is configured to perform (optional) step S 116 : 
     S 116 : The server node  200  forwards media of the media transmission to other client nodes  160   b ,  160   c  in the group of client nodes. 
     Reference is now made to  FIG. 4  illustrating a method for resource allocation for group communication in a network  100  as performed by the core network node  300  according to an embodiment. 
     As disclosed above, the server node  200  in step S 104  requests, from the core network node  300 , a first allocation of network resources. Hence, the core network node  300  is configured to perform step S 202 : 
     S 202 : The core network node  300  receives, from the server node  200  of the group communication system, a first request. The first request is for first network resources to be used by client node  160   a  of a group communication session of the group communication system. The first network resources are to be used by client node  160   a  for transmission control of the group communication session. 
     The network resources are to be made available in the radio access network  110  and the core network node  300  therefore requests the necessary network resources from the radio access network  110 . Hence, the core network node  300  is configured to perform step S 204 : 
     S 204 : The core network node  300  requests a radio access network of the client node  160   a  to make the first network resources available to the client node  160   a.    
     As further disclosed above, the server node  200  in step S 110   a  requests, from the core network node  300 , a second allocation of network resources. Hence, the core network node  300  is configured to perform step S 206 : 
     S 206 : The core network node  300  receives, from the server node  200 , a second request for second network resources. The second network resources are to be used by the client node  160   a  for media transmission in the group call. 
     Also these network resources are to be made available in the radio access network  110  and the core network node  300  therefore requests the necessary network resources from the radio access network  110 . Hence, the core network node  300  is configured to perform step S 208 : 
     S 208 : The core network node  300  requests the radio access network of the client node  160   a  to make the second network resources available to the client node  160   a.    
     The first request and the second request are received during one and the same SIP session or SAP session. 
     Embodiments relating to further details of resource allocation for group communication in a network  100  as performed by the core network node  300  will now be disclosed. 
     As disclosed, according to some aspects the server node  200  in step S 104  specifies the media type for the network resources as control. Thus, according to an embodiment the first request for network resources (as received in step S 202 ) comprises a message indicating media type as control. The core network node  300  could use this information, i.e. that the media type is control, to determine the necessary amount of network resources to request from the radio access network for the client node  160   a  in step S 204 . 
     As further disclosed, according to some aspects the server node  200  in step S 110   a  specifies the media type for the network resources as audio or video. Thus, according to an embodiment the second request (as received in step S 206 ) for network resources comprises a message indicating media type as audio or video. The core network node  300  could use this information, i.e. that the media type is audio or vide, to determine the amount of necessary network resources to request from the radio access network for the client node  160   a  in step S 208 . 
     There could be different types of core network nodes  300 . According to an embodiment the core network node  300  is a Policy and Charging Rules Function (PCRF) node. As is known by the skilled person the PCRF node is designated to in real-time determine policy rules in a multimedia network. 
     There could be different examples of network resources. In general terms, the network resources relate to radio resources, i.e., resource to be used for transmission of data and control between the wireless devices of the client nodes and the radio access network nodes of the radio access network. In particular, according to an embodiment the network resources are radio resources in frequency and/or time domain, and/or transport resources in terms of transmission network capacity. Optionally, the network resources could relate to resources for transmission of data and control between the radio access network and the core network and/or between the core network and the service network. 
       FIG. 5  schematically illustrates a SIP session for a group call according to an embodiment. “DT” is short for data transmission. In comparison to the SIP session for a group call illustrated in  FIG. 2 , according to the SIP session for a group call in  FIG. 5  at group affiliation the group communication session is established and network resource are allocated for transmission control but not for the media transmission. The network resources for the media transmission are only allocated at the group call setup. 
     One particular embodiment for resource allocation for group communication in a network  100  based on at least some of the above disclosed embodiments will now be disclosed in detail with reference to the signalling diagram of  FIG. 6 . There might be several client nodes  160   a ,  160   b ,  160   c  involved in a group call. For clarity and ease of description, but without loss of generality, the signalling diagram in  FIG. 6  only shows three such client nodes  160   a ,  160   b ,  160   c.    
     S 301 : Client node  160   a  requests to affiliate with the group. The server node  200  thus receives a request from client node  160   a . This implies that client node  160   a  intends to participate in any group communication related to the group. Once step S 301  has been completed client node  160   a  will be able to transmit and/or receive media in the specific group. One way to implement step S 301  is to perform step S 102 . 
     S 302 : The server node  200  allocates the required network resources for transmission control for the group communication session (such as floor control in a PTT system). One way to implement step S 302  is to perform step S 104  and steps S 202 , S 204 . 
     S 303 : The server node  200  and client node  160   a  sets up a group communication session. Setting up the group communication session comprises negotiation of media attributes for the group communication session, such as codecs to be used, Internet Protocol (IP) addresses, and ports. One way to implement step S 303  is to perform step S 106 . 
     Furthermore, it is assumed that each client node  160   a ,  160   b ,  160   c  affiliates with the group and thus joins the group communication. It is thus assumed that separate occurrences of steps S 301 -S 303  have been performed for client nodes  160   b ,  160   c  either before or after steps S 301 -S 303  for client node  160   a , but before below step S 304 . Steps S 301 , S 302 , S 303  can be regarded as preparations steps and may occur a long time ahead of step S 304 . 
     S 304 : Client node  160   a  starts a group call by sending a group call request, which usually means that client node  160   a  also requests the right to transmit media data in the group call, thus requesting floor control. One way to implement step S 304  is to perform step S 108 . 
     S 305 : The server node  200  allocates the required network resources for media transmission in the group call for client node  160   a  as well as for the rest client nodes  160   b ,  160   c  in the group call. One way to implement step S 305  is to perform steps S 110   a , S 110   b  and steps S 206 , S 208 . 
     S 306 : The server node  200  notifies all client nodes  160   a ,  160   b ,  160   c  that have affiliated with the group about the call start and may grant the right to transmit media to client node  160   a . One way to implement step S 306  is to perform step S 112 . 
     S 307 : Client node  160   a  transmits media to the server node  200 . The server node  200  forwards the media to the remaining client nodes  160   b ,  160   c  in the group call. One way to implement step S 307  is to perform steps S 114 , S 116 . 
     As is understood by the skilled person, at least some of the messages communicated between the server node  200  and the client nodes  160   a ,  160   b ,  160   c , between the server node  200  and the core network node  300 , and between the core network node  300  and the radio access network and that are related to requests are followed by acknowledgement messages once the request has been granted, that is once the requested network resources have been made available, or made accessible, for transmission control or data transmission. It is here thus assumed that the network resources as requested are granted and thus made available, or made accessible, for transmission control or data transmission for the client nodes  160   a ,  160   b ,  160   c . However, in order not to obscure the inventive concept as described herein, the mentioning of such acknowledge messages, or the like, has been omitted. 
     Further, the terms group call and group communication session do not exclude that other types of media than voice is transmitted. Thus, the media transmission could include voice data or other types of audio data, text data, image data, video data, or any combination thereof. 
     In summary, according to at least some of the herein disclosed embodiments utilize the concept of pre-established sessions, which means that a SIP session or SAP session could be established long time before the actual group call starts. Furthermore, the radio access network is configured to only allocate resources needed to control the media transmission (that is, network resources are to be used by the client node  160   a  for transmission control, such as floor control messages, of the group communication session. The network resources needed for media transmission are allocated only once the group call starts, and thus not at SIP session or SAP session establishment. The network resources allocated for media transmission are thereby managed independently from the network resources allocated for transmission control. 
       FIG. 7  schematically illustrates, in terms of a number of functional units, the components of a server node  200  according to an embodiment. Processing circuitry  210  is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product  1110   a  (as in  FIG. 11 ), e.g. in the form of a storage medium  230 . The processing circuitry  210  may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA). 
     Particularly, the processing circuitry  210  is configured to cause the server node  200  to perform a set of operations, or steps, S 102 -S 116 , as disclosed above. For example, the storage medium  230  may store the set of operations, and the processing circuitry  210  may be configured to retrieve the set of operations from the storage medium  230  to cause the server node  200  to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry  210  is thereby arranged to execute methods as herein disclosed. 
     The storage medium  230  may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory. 
     The server node  200  may further comprise a communications interface  220  for communications with other entities, nodes, functions, and devices in the network  100 . As such the communications interface  220  may comprise one or more transmitters and receivers, comprising analogue and digital components. 
     The processing circuitry  210  controls the general operation of the server node  200  e.g. by sending data and control signals to the communications interface  220  and the storage medium  230 , by receiving data and reports from the communications interface  220 , and by retrieving data and instructions from the storage medium  230 . Other components, as well as the related functionality, of the server node  200  are omitted in order not to obscure the concepts presented herein. 
       FIG. 8  schematically illustrates, in terms of a number of functional modules, the components of a server node  200  according to an embodiment. The server node  200  of  FIG. 8  comprises a number of functional modules; a receive module  210   a  configured to perform step S 102 , a request module  210   b  configured to perform step S 104 , a receive module  210   d  configured to perform step S 108 , and a request module  210   e  configured to perform step S 110   a . The server node  200  of  FIG. 8  may further comprise a number of optional functional modules, such as any of an establish module  210   c  configured to perform step S 106 ; a request module  210   f  configured to perform step S 110   b ; an indicate module  210   g  configured to perform step S 112 ; a receive module  210   h  configured to perform step S 114 ; and a forward module  210   i  configured to perform step S 116 . In general terms, each functional module  210   a - 210   i  may be implemented in hardware or in software. Preferably, one or more or all functional modules  210   a - 210   i  may be implemented by the processing circuitry  210 , possibly in cooperation with the communications interface  220  and/or the storage medium  230 . The processing circuitry  210  may thus be arranged to from the storage medium  230  fetch instructions as provided by a functional module  210   a - 210   i  and to execute these instructions, thereby performing any steps of the server node  200  as disclosed herein. 
       FIG. 9  schematically illustrates, in terms of a number of functional units, the components of a core network node  300  according to an embodiment. Processing circuitry  310  is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product  1110   b  (as in  FIG. 11 ), e.g. in the form of a storage medium  330 . The processing circuitry  310  may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA). 
     Particularly, the processing circuitry  310  is configured to cause the core network node  300  to perform a set of operations, or steps, S 202 -S 208 , as disclosed above. For example, the storage medium  330  may store the set of operations, and the processing circuitry  310  may be configured to retrieve the set of operations from the storage medium  330  to cause the core network node  300  to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry  310  is thereby arranged to execute methods as herein disclosed. 
     The storage medium  330  may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory. 
     The core network node  300  may further comprise a communications interface  320  for communications with other entities, nodes, functions, and devices in the network  100 . As such the communications interface  320  may comprise one or more transmitters and receivers, comprising analogue and digital components. 
     The processing circuitry  310  controls the general operation of the core network node  300  e.g. by sending data and control signals to the communications interface  320  and the storage medium  330 , by receiving data and reports from the communications interface  320 , and by retrieving data and instructions from the storage medium  330 . Other components, as well as the related functionality, of the core network node  300  are omitted in order not to obscure the concepts presented herein. 
       FIG. 10  schematically illustrates, in terms of a number of functional modules, the components of a core network node  300  according to an embodiment. The core network node  300  of  FIG. 10  comprises a number of functional modules; a receive module  310   a  configured to perform step S 202 , a request module  310   b  configured to perform step S 204 , a receive module  310   c  configured to perform step S 206 , and a request module  310   d  configured to perform step S 208 . The core network node  300  of  FIG. 10  may further comprise a number of optional functional modules. In general terms, each functional module  310   a - 310   d  may be implemented in hardware or in software. Preferably, one or more or all functional modules  310   a - 310   d  may be implemented by the processing circuitry  310 , possibly in cooperation with the communications interface  320  and/or the storage medium  330 . The processing circuitry  310  may thus be arranged to from the storage medium  330  fetch instructions as provided by a functional module  310   a - 310   d  and to execute these instructions, thereby performing any steps of the core network node  300  as disclosed herein. 
     The server node  200  and/or core network node  300  may be provided as separate standalone devices or be a part of at least one further device. For example, the server node  200  may be provided in a node of the service network, and the core network node  300  may be provided in a node of the core network. For example, the server node  200  could be implemented in, co-located with, or part of, a GC server node, an MC service server, and/or an BMSC. For example, the core network node  300  could be implemented in, co-located with, or part of a PCRF node. 
     Alternatively, functionality of the server node  200  and/or core network node  300  may be distributed between at least two devices, or nodes. These at least two nodes, or devices, may either be part of the same network part or may be spread between at least two such network parts. Thus, a first portion of the instructions performed by the server node  200  and/or core network node  300  may be executed in a first device, and a second portion of the of the instructions performed by the server node  200  and/or core network node  300  may be executed in a second device; the herein disclosed embodiments are not limited to any particular number of devices on which the instructions performed by the server node  200  and/or core network node  300  may be executed. Hence, the methods according to the herein disclosed embodiments are suitable to be performed by a server node  200  and/or core network node  300  residing in a cloud computational environment. Therefore, although a single processing circuitry  210 ,  310  is illustrated in  FIGS. 7 and 9  the processing circuitry  210 ,  310  may be distributed among a plurality of devices, or nodes. The same applies to the functional modules  210   a - 210   i ,  310   a - 310   d  of  FIGS. 8 and 10  and the computer programs  1120   a ,  1120   b  of  FIG. 11  (see below). 
       FIG. 11  shows one example of a computer program product  1110   a ,  1110   b  comprising computer readable means  1130 . On this computer readable means  1130 , a computer program  1120   a  can be stored, which computer program  1120   a  can cause the processing circuitry  210  and thereto operatively coupled entities and devices, such as the communications interface  220  and the storage medium  230 , to execute methods according to embodiments described herein. The computer program  1120   a  and/or computer program product  1110   a  may thus provide means for performing any steps of the server node  200  as herein disclosed. On this computer readable means  1130 , a computer program  1120   b  can be stored, which computer program  1120   b  can cause the processing circuitry  310  and thereto operatively coupled entities and devices, such as the communications interface  320  and the storage medium  330 , to execute methods according to embodiments described herein. The computer program  1120   b  and/or computer program product  1110   b  may thus provide means for performing any steps of the core network node  300  as herein disclosed. 
     In the example of  FIG. 11 , the computer program product  1110   a ,  1110   b  is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product  1110   a ,  1110   b  could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program  1120   a ,  1120   b  is here schematically shown as a track on the depicted optical disk, the computer program  1120   a ,  1120   b  can be stored in any way which is suitable for the computer program product  1110   a ,  1110   b.    
     The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.