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(11) Patent Number: KE 312
(45) Date of grant: 27/04/2009
(51) Int.CL8: H 04L 12/18, H 04Q 7/22
(21)Application Number: KE/P/ 2008/ 000727
(84) WO No. WO 2007/036604 Al
(22) Filing Date: 26/09/2006
(31)Priority Number: 20055514
(32) Date: 27/09/2005
(33) Country: FI
(73) Owner(s): NOKIA CORPORATION of Keilalandentie 4, FIN-02150 Espoo, Finland
(72) Inventor(s) LAURILA, Antti and POIKSELKA, Miikka
(74)Agent/address for correspondence: ANJARWALLA & KHANNA ADVOCATES,
(54) Title: GROUP COMMUNICATION IN COMMUNICATION SYSTEM.
(57) Abstract: In a communication system providing a group communication service and
advertisement of an existing and newly created group, information on usable media
types in the group members in a message advertising the group. The message
contains either a new field for the information or an existing field is extended to
contain the information.
GROUP COMMUNICATION IN COMMUNICATION SYSTEM
FIELD OF THE INVENTION
 The present invention relates to group communication in communication systems providing a group communication service.
BACKGROUND OF THE INVENTION
 One special feature offered in mobile communication systems is group communication. The term “group”, as used herein, refers to any logical group of two or more users intended to participate in the same group communication. One example of group communication is a group call, which is a call in which all participants may take turns to speak and to listen to each other.
 Conventionally, group communication has been available only in trunked mobile communication systems, such as Professional Mobile Radio or Private Mobile Radio (PMR) systems, such as TETRA (Terrestrial Trunked Radio), which are special radio systems primarily intended for professional and governmental users. Thanks to the evolvement of communication technology, particularly IP-based communication technology, and end user equipment, a group communication service is now available also in public mobile communication systems. Examples of services providing group communication service include Push-to-talk over Cellular (PoC), messaging (IM), and conferencing, all implemented using primitives provided by SIP (Session Initiation Protocol) which is not vertically integrated into a communication system but a tool to build a multimedia architecture. Such group communication may include data calls, audio calls, video calls, multimedia calls, messaging, electronic mail, etc.
 Due to the versatile communication possibilities, different media tykes can be usable in a group, such as a Voice PoC call, SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions) IM that, Video PoC call and Gaming Service. However, for the time being no mechanism exist with which group members can be informed about usable media type(s) in a group. (A group member is a user intended to participate in the group communication.) Thus, group members have to guess the usable media type(s) in the group.
BRIEF DESCRIPTION OF THE INVENTION
 An object of the present invention is thus to method and an apparatus for implementing the method so as to overcome the above problem and to provide group members with information on usable media type(s) in a group. The object of the invention is achieved by a method, a signalling message, user equipment, a server.and a computer program product, which are characterized by what is stated in the independent claims. Preferred embodiments of the invention are disclosed in the dependent claims.
 The invention is based on realizing the problem and solving it by enhancing a message informing group members about an existing group, called herein a message advertising a group, to contain a usable media type or usable media types in the group.
 The present invention provides an easy-to-implement solution for informing group members about usable media types in the group. An advantage is that the user equipment, on the basis of the usable media type or types, knows which application It should use for communication in this group. A further advantage is that since me information is delivered in a message advertising a group, no extra signalling is needed and no resources need to be allocated to pass the information to intended group members.
BRIEF DESCRIPTION OF THE DRAWINGS
 In the following, the invention will be described in greater detail by means of preferred embodiments and with reference to the accompanying drawings, in which
 Figure 1 illustrates an example of a general architecture of a
communication system providing a group communication service;
 Figures 2 and 3 illustrate different group advertisement
messages according to the invention; and
 Figure 4 is a signalling diagram illustrating signalling according to an embodiment of the invention.
DETAILED DESCRIPTION OF SOME EMBODIMENTS
 The following embodiments are exemplary. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations, this does not necessarily mean that each such reference is made to the same embodiment(s), or that the feature only applies to a single
embodiment. In addition, the embodiments presented below or parts thereof can be combined to produce preferred embodiments of the invention.
 The present invention is applicable to any user equipment, servers and/or to any communication system or any combination of different communication systems that support group communication and provide(s) messages with which a group is advertised to group members. No limitations exist to the message format, nor to the group type. The communication system may be a fixed communication system or a wireless communication system or a communication system utilizing both fixed networks and wireless networks.
The protocols used, the specifications of communication systems and user equipment, especially in wireless communication, develop rapidly. Such development may require extra changes to the invention. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the invention.
 In the following, the present invention will be described using, as an example of a system architecture whereto the present invention may be applied, an architecture based on SIP providing a tool to build a multimedia architecture and utilizing XDM (XML Document Management) without restricting the invention to such an architecture, however. SIP is an
Internet Engineering Task Force (IETF) defined application-layer control (signalling) protocol for creating, modifying, and terminating sessions with one or more participants. Open Mobile Alliance (OMA) has defined XDM as a generic framework for group and list management based on XCAP protocol (XML Configuration Access Protocol). IETF specifications and Internet Drafts
can be found at http://www.ietf.org, and OMA specifications at http://www.openmobilealliance.org.
 A general architecture of a communication system providing
a group communication service utilizing SIP and XCAP is illustrated in Figure
1. Figure 1 is a simplified system architecture only showing some elements and functional entities, all being logical units whose implementation may differ from what is shown. The connections shown in Figure 1 are logical connections; the actual physical connections may be different. It is apparent to a person skilled in the art that the systems also comprise other functions and structures. It should be appreciated that the functions, structures, elements
and the protocols used in or for group communication or for advertising a group, are irrelevant to the actual invention. Therefore, they need not to be discussed in more detail here. The present invention primarily relates to informing group members about usable media types in a group, the information being given in a message advertising the group.
 The communication system 1 comprises user equipment (UE) 1-2, such as a mobile station, which is connectable to an aggregation proxy 1-3, application server 1-4 and to an IP Multimedia Subsystem (IMS) 1-5, and via them to an application XML Document Management Server (XDMS) 1-6 and a shared XDMS 1-7. As functional entities, UE 1-2 contains an application client 1-21 with which the service provided by the application is accessed, and an XML Document Management Client (XDMC) 1-22 with which XML documents, or an element/elements within an XML document, may be created, deleted, modified and retrieved, for example. Typically, control plane traffic, such as SIP signalling, passes through IMS 1-5 but user plane traffic passes between UE 1-2 and the application server 1-4. Group and list management traffic using the XCAP protocol goes between UE (or, more precisely, XDMC 1-22 in the UE) and the application XDMS 1-6 or the shared XDMS 1-7 via the aggregation proxy 1-3.
 The aggregation proxy 1-3, application XDMS 1-6 and shared XDMS 1-7 are XDM functional entities. XDM defines a common mechanism that makes user-specific service-related information, such as group definitions, accessible to different applications (service enablers) and clients residing in user equipment, and enables creation, modification, retrieval and deletion of such information. The information, more precisely, XML documents, are stored in XDMSs. The application XDMS 1-6 is an application-specific server, i.e. it is serves one or more application servers, each for the same particular application, whereas the shared XDMC 1-7 serves application servers for different applications in the system and contains generic group and list management data. The aggregation proxy 1-3 routes an individual XCAP request from the XDMC to the correct XDMS.
 The application server 1-4 comprises one or more application units providing the group communication service, one or more receivers for receiving and one or more transmitters for sending communications (messages), memory and one or more operation processors
or processing one or more applications providing the group communication service, for processing and controlling receiving and sending communications and for controlling the use of the memory. It is apparent to a person skilled in the art that the server may comprise other components, entities, functions and structures that need not be described in detail herein. The application providing the group communication service may be a software application, or a module, or a unit configured as arithmetic operation, or as a program, executed by the
operation processor, for example. The application providing the group communication service may be PoC, messaging, or conferencing, for example. PoC specification is currently being developed by a PoC working group under the OMA. More detailed information on the PoC can be found via the above-mentioned Internet pages of OMA. SIMPLE, defined by IETF, provides instant messaging (IM) service. OMA also defines IM (Instant Messaging) enabler based on SIP/SIMPLE protocols. Thus, the application server 4 may be a PoC server, an instant messaging server, or a conference server that supports different media types, such as audio, video and messaging. Since the application XDMS 1-6 serves a single application, the application XDMS 1-6 may be a PoC XDMS or instant messaging XDMS. For example, when the application is PoC, contact lists may be stored in the shared XDMS 1-7 and/or in the PoC XDMS, i.e. application XDMS 1-6, which contains PoC group documents. A PoC group document providing a member list for a PoC group session is thus accessible to UE 1-2 and to a PoC server, i.e. the application server 1-4, and they can utilize the member list when advertising the group or when establishing a group session (inviting group members to a group session). The PoC group document according to the invention preferably also contains usable media types in the group in addition to member list.
 UE 1-2 comprises one or more application client units 1-21
25 according to an embodiment of the invention, called an application client below, one or more document management client units (XDMC) 1-22, memory, one or more receivers for receiving and one or more transmitters for sending communications (messages), and one or more operation processors for processing one or more application clients and document management clients, for processing and controlling receiving and sending communications, and for controlling the use of the memory. It is apparent to a person skilled in the art that the user terminal may comprise other components, entities, functions and structures that need not be described in detail herein. UE 1-2, or more specifically, the application client 1-21, allows, among other things, application session initiations and provides access to different group lists and contact lists. The application client according to the invention or the user equipment in which
the application client resides may be configured to form and send messages advertising a group, add information on usable media types in a group to a message advertising the group, and to store the information on usable media types in the group, as illustrated in Figures 2 to 4. The application client according to the invention 1-21 may be shipped with the user equipment, or it may be a downloadable plug-in to the user equipment, otherwise later added to the user equipment, or an application client in the user equipment may be modified to be an application client according to the invention. For example, the application client may be a software application, or a module, or a unit configured as arithmetic operation, or as a program, executed by the operation processor.
 Figures 2 and 3 disclose messages according to the invention, both being messages advertising an existing group. The messages may be any suitable signalling messages but, for the sake of clarity, they are
illustrated as a simplified SIP MESSAGE not containing, for the sake of clarity, all possible SIP headers and parameters. In the illustrated architecture, the messages are sent over IMS and they are immediate messages or page-mode messages. A feature common to those messages is that a message is created and sent to a recipient/recipients via network infrastructure and that a subsequent message is not related, at the protocol level, to the preceding one: each immediate or page-mode message, even a reply to a previous message, is considered to be an independent transaction. In other words, a message advertising a group is not a session-based messaging message but an independent transaction.
 In the embodiment illustrated in Figure 2, a message 2 contains a new field ‘communication means’ 2-1 to define usable media type(s) in this group, whereas in the embodiment illustrated in Figure 3, the current field 'group type' is extended to define usable media type(s) 3-1, 3-1’. The new field 2-1 in Figure 2 may also have another name. As regards the embodiment of Figure 3, some other current field may be extended to define a usable media
type. A media type covers here a general type of data and/or communication means which are negotiable between endpoints, i.e. UEs. Examples of media types include top-level media types defined by IETF in RFC 2046, Multipurpose Internet Mail Extensions (MIME) Part two: Media Types, November 1996. The top-level media types include, but are not limited to, text
(textual information), image (image data), audio (audio data), video (video
data), application (some other kind of data, typically either uninterpreted binary data or information to be processed by an application), multipart (data consisting of multiple entities of independent data types) and message (an encapsulated message). In addition, media types contain different sub-types and/or connection types (including different overlay services) providing group communication services. Thus, media types may be selected from the group of 'poc', 'im', 'audio', 'video', 'conference', 'application', 'all', 'other', for example.
 In both illustrated examples, two media types, media_type1 and media_ type2, are defined to be usable media types in the advertised
group. However, there may be one, two, three or more usable media types in a group; the amount is unlimited. Preferably, the message contains all possible usable media types in the group since the usable media types only indicate what media types can be used in the group but they do not necessitate using media components of all usable media types in group communication. For example, if usable media types in a group are audio, video and messaging, it is possible that only audio is used during a group communication session of the group.
 If a new usable media type is added to group definitions, or an existing usable media type is deleted from the group definitions, messages advertising the group are amended accordingly, and preferably sent after the amendment.
 Figure 4 illustrates signalling according to an embodiment of the invention. In the example illustrated in Figure 4, it is assumed, for the sake of clarity, that group advertisement is activated and sent to all group members. An advantage of sending the message advertising the group to all group members is that each group member will have the same information on usable media types in the group. This enables the same user experience to all group members immediately. This is especially advantageous when usable media types are modified while a group exists.
 In the illustrated example, the user equipment UE1, or more precisely, the user of UE1, creates, in point 4-1, a group using normal procedures. How the group is created bears no significance to the invention and therefore it is not discussed in detail here. In addition to prior art group definitions, the UE1 (the user) defines, in point 4-1, the usable media types for
the created group. For example, the user equipment may show to the user all possible media types among which the user selects the ones he/she wishes to be usable with this group, or the user equipment may have a preset definition of usable media types, the preset definition being stored in the user equipment and used as a default However, the details of how the usable media types are defined are irrelevant to the invention; it will suffice that usable media type(s) are added to the message advertising the group. When the group has been created and definitions are ready, the information on the group is forwarded by XDMC to the system and stored either in the application XDMS or in the shared XDMS using normal procedures. Then, either immediately or after a while, the UE1, or actually the application client in question in the UE1, forms,in point 4-2, a message advertising the group. The message either contains a new field (disclosed in Figure 2) for usable media types or an extended field for group type (disclosed in Figure 3). When the message is ready, the UE1 sends it (message 4-3) to the network. When the message arrives at the corresponding application server, it then preferably performs group advertisement policy and distribution checking using normal procedures. Then the application server delivers message 4-3 to the UEs of the group members (depending on the configuration, the UE1 receives or does not receive message 4-3).
 When the UEs of the other group members (or the UE of another group member if the group only contains two members) receive message 4-3, they may store, in point 4-4, group information containing usable media type(s) to be used later with the group. The usable media type(s) may be shown to the user when the user wishes to invite other members to a group communication session, or when a user is responding to a group communication, for example.
 The application server may be arranged to send messages advertising the group without receiving an advertisement from a group creator, the messages being sent to all group members or to a selected subset of the group members. Such an application server is illustrated in US patent application No. 10/880,982 of the same applicant, which US patent application
is incorporated herein by reference. (A corresponding PCT application is PCT/FI2005/050137). In embodiments in which the application server may also advertise the group, the application server is preferably also configured to send messages advertising the group member(s), including the creator, with information on the usable media types. In other words, the application server
may send messages 4-3 to group members although the application server did not receive message 4-3.
 In some other embodiment of the invention, messages advertising a group and containing information on usable media types may be sent without using the application server, i.e. the UE1 sends message 4-3 directly to other group members or to another group member.
 The points and signalling messages shown in Figure 4 are in no absolute chronological order, and some of the points/signalling may be performed simultaneously. Other functions can also be executed or other signalling messages sent between the points/signalling messages or within the points.
 The user equipment, servers or corresponding server components and/or other corresponding devices implementing the functionality of the present invention comprise not only prior art means but also means for forming, sending and/or receiving messages advertising the group and containing information on usable media types in the group in the manner described above. Present servers and user equipment comprise processors and memory that can be utilized in the functions according to the invention. All modifications and configurations required for implementing the invention may be performed as routines, which may be implemented as added or updated software routines, application specific integrated circuits (ASIC) and/or programmable circuits. Software routines, also called program products, including applets and macros, can be stored in any device-readable data storage medium and they include program instructions to perform particular tasks. Software routines may be downloaded into a device. The user equipment, servers or corresponding server components and/or other corresponding devices may be configured as a computer including at least a memory for providing storage area used for arithmetic operation and an operation processor for executing the arithmetic operation. An example of the operation processor includes central processing unit.
 It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.
1. A method comprising:
adding to a message advertising a group in a communication system an indication of usable media types in the group, the usable media types containing at least one media type.
2. A method as claimed in claim 1, further comprising sending the message to at least one intended group member to advertise the group.
3. A method as claimed in claim 1 or 2, further comprising storing the usable media types in the group in response to receiving the message.
4. A method as claimed in claim 1, 2 or 3, wherein the message is sent to all users intended to participate to the group communication of the advertised group.
5. A method as claimed in any of the preceding claims, wherein the message contains a field for the information on usable media types in the group.
6. A method as claimed in any of the preceding claims, wherein an existing field in the message is extended to contain the information on usable media types in the group.
7. A method as claimed in claim 6, wherein the field is a field for group type.
8. A method message as claimed in any one of the preceding
claims, wherein the usable media types include 'poc', 'im', 'audio', 'video', 'conference', 'application', 'all', and/or 'other'.
9. A method as claimed in any one of the preceding claims, wherein 25 the message contains all usable media types in the group.
10. An apparatus comprising:
means for forming a signalling message advertising a group in a communication system, the message containing information on usable media types in the group, the usable media types containing at least one media type; and
means for sending the signaling message
11. An apparatus as claimed in claim 10, wherein the means for forming are configured to add the information on usable media types to a field in the message, the field being for the information on usable media types in the ponent is a group communication server.
24. A computer program product comprising program instructions, wherein execution of said program instructions cause a processor to perform method, according to any of claims 7 to 9.