Abstract:
A method and terminal device are provided which effect the steps of receiving a message indicating that a user of another terminal device has pressed a talk button, the message including a geographical location of the other terminal device, or any information derived therefrom; and indicating the geographical location of the other terminal device to a user of the terminal device. A further method and terminal device are provided which effect the steps of: in response to a user of a terminal device pressing a talk button, writing information describing the geographical location of the terminal device, or any information derived therefrom, into a message; and sending the message to another terminal device or to a communications network.

Description:
BACKGROUND OF THE INVENTION 
     Push-to-Talk over Cellular, PoC, is a relatively new service offered in some cellular networks, and has gradually gained more success on the market. In PoC, one subscriber can transmit speech to another subscriber or a group of subscribers simply by pressing a speak button. The transmission is half-duplex only; i.e., only one party can speak at a time. 
     The communication channel between the parties of the conversation is usually a packet-switched communication channel which is preferably established at the very beginning of the service. As a consequence, a speech message, having speech coded at the terminal device, usually can be transferred almost instantaneously without an annoying delay due to the establishment of the packet switched communication channel between the individual speech messages that are to be transmitted. 
     A user receiving a Push-to-Talk over Cellular message cannot know the geographical location of the talking party without asking it from the speaker, which is time-consuming and, when PoC is used as a group service, can be annoying to the others who then hear the reply as well. 
     SUMMARY OF THE INVENTION 
     The present invention is therefore directed toward enabling a party of a conversation to obtain location information of another party in a convenient way. 
     If the geographical location information is received at a terminal in a message that indicates that a user of another terminal device has pressed a talk button, it is clearly advantageous that one party of the conversation does not need to ask the other party about his or her whereabouts. Furthermore, the geographical location information may become important for the recipient only at the point when the user of the other terminal device is going to say or is saying something, and has therefore pressed the talk button. In this manner, it can be ensured that the user obtains the geographical location when he or she needs it or has any interest in it, not too early or not too late. 
     Indicating the geographical location can be performed in many ways. This is particularly useful if the geographical location is indicated to the user of the terminal device in relation to his or her own geographical location. This helps the party receiving the speech message to sense the direction where the speech is actually coming from. This may improve the user&#39;s feeling of mutual understanding, or help to locate the other user in a crowded area. Particularly advantageous embodiments for carrying out this feature are: indicating a direction of the terminal device from the geographical location of the other terminal device; indicating a distance of the terminal device from the other terminal device; indicating the geographical location of the terminal device on a map together with the location of the other terminal device; and indicating the coordinates of the terminal device as well as those of the other terminal device. 
     If the geographical location information is written into a message that is transmitted to another terminal device either directly or via a network, it is advantageous that one party of the conversation does not need to tell the other party about his or her whereabouts. 
     Nevertheless, in order to avoid privacy problems and any conflicts with the legislator in some countries, it may become necessary to enable user control over the decision whether or not geographical location information may be sent. 
     Therefore, by setting a parameter controllable by a user of the terminal device, sending the geographical location information can be disabled or enabled. In this manner, it is also possible to use, for example, the PoC service without revealing the address. 
     Furthermore, if the parameter controllable by a user of the terminal device shows that the geographical location may be indicated to another device to which the message, or any message derived therefrom, is going to be sent, partial anonymity can be guaranteed. In this manner, for example, parents may ensure that the child&#39;s geographical location is transmitted to parents and/or trusted friends only, but not to unknown people that might cause harm to the child. 
     Common to all embodiments of the present invention is that if the message is a message that would, in any case, be sent to the other party, some traffic can be avoided since no dedicated geographical location messages need to be transmitted any more. 
     If the present invention is used in connection with PoC, such messages are then preferably Push-to-Talk over Cellular messages. Some special cases of these messages are a REFER message, a Floor taken message, or a Talk burst, since they are sent, in any case, if a speech message is transmitted between two terminal devices. 
     Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and the Figures. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1A  shows a modern network architecture for enabling a PoC service. 
         FIG. 1B  shows a simplified functional block diagram of a terminal device. 
         FIG. 2  illustrates the implementation of a PoC service. 
         FIG. 3  shows an exemplary signalling diagram for PoC. 
         FIGS. 4 and 5  show more detailed signalling diagrams for PoC. 
         FIG. 5  is another model case for PoC. 
         FIGS. 6A and 6B  illustrate possible structures of the message carrying geographical location information. 
     
    
    
     Same reference numerals refer to similar elements throughout  10  the Figures. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1A  shows a modern network architecture for enabling the PoC service. A terminal device  101 , sometimes denoted as user equipment, such as a mobile terminal or a portable digital assistant, can be in wireless connection with a communications network  100  or with another terminal device. 
     The communications network  100  may include a GSM/EDGE Radio Access Network  103  which is further connected to a Circuit-Switched Core Network  105  and a Packet-Switched Core Network  107 . The latter is further connected to an IP-based Multimedia Subsystem IMS  109  which resembles, more or less, the Internet. The PoC service can be located in the Internet  111  or in any IP-based network. 
       FIG. 1B  shows a simplified functional block diagram of a terminal device  101 . The terminal device  101  includes receiving part  151 , transmitting part  153 , processing unit  155 , memory  161 , voice input part  157  and voice output part  159 , visual indication part  163 , and push button  167 . The processing unit can run application  165  for offering the PoC service. The receiving part  151  and the transmitting part  153  may enable the terminal device  101  to be in communication with the communications network  100  or with another terminal device. 
     An example of the voice input part  157  is a microphone, and an example of the voice output part  159  a loudspeaker. A skilled person appreciates that some fundamental components (e.g., rechargeable battery or any other energy source, amplifiers, antennas, etc.) have been omitted from  FIG. 1B  for clarity. These features are nevertheless rather well known per se such that omitting them does not make understanding the present invention any more difficult. 
       FIG. 2  illustrates the implementation of the PoC service. The Packet-Switched Core Network  107 A, through which the terminal device  100  can have its connections, is connected to the IMS  109 A Most messages are routed via IMS core  203 A. The PoC server  201  can be in the Internet  111 . 
     Another terminal device can be connected either to the same Packet-Switched Core Network  107 A or to another Packet-Switched Core Network  107 B; e.g., of another communications network  100 B. The Packet-Switched Core Network  107 B is connected to the IMS  109 B which further includes IMS Core  203 B. The IMS  109 A may communicate with the IMS  109 B either directly or via the Internet  111 . 
       FIG. 3  shows an exemplary signalling diagram for PoC. The user at the terminal device  101  presses the talk button  167 . The terminal device  101  sends a request to the PoC server  201  which is in “Floor Idle” state (step  301 ). The PoC server  201  notifies the other terminal device  101 B by sending a notification J 13 , grants the floor and notifies the terminal device  101  by sending an acknowledgement J 15 . Then the terminal device  101  signals the user Talk proceed-notification; e.g., by alerting the user with voice output part  159 . The user starts speaking, and speech received by the voice input part  157  is coded and transmitted in packets M 11 , M 21 , M 31 , M 41 , . . . , M 51  to the PoC server  201  which further forwards the messages to the other terminal device  101 B as packets M 12 , M 22 , M 32 , M 42 , . . . , M 52 . 
     The user can speak as long as the talk button  167  is pressed. After releasing the talk button  167 , the terminal device  101  signals the release of the talk button to the PoC server  201  by sending a message J 21 . The PoC server  201  notifies the other terminal device  101  by sending a message J 23 , and then sends an acknowledgement J 25  to the terminal device  101 . Then, the PoC server  201  returns to the Floor Idle state, as designated at step  301 . 
       FIGS. 4 and 5  show more detailed signalling diagrams for PoC. 
       FIG. 4  shows a case where both terminal devices have enabled so-called early session and automatic answer. 
     Dashed box  41  shows how a session is created. When terminal device  101  is switched on, it sends an SIP INVITE message to the IMS core  203 A which further forwards the message to PoC server  201 , which responds with SIP 200 OK that is forwarded by the IMS core  203 A to the terminal device  101 . The terminal device  101  responds with an acknowledgement SIP ACK. The other terminal  101 B performs similar messaging with the PoC server  201 . 
     Dashed box  43  shows how a PoC is then used. When the talk button  167  is pressed at a terminal device  101 , the terminal device  101  sends message J 11 , which is a SIP REFER message. The IMS core  203 A forwards message J 11  to PoC server which transmits message J 13  that is RTCP: Floor taken message to the other terminal device  101 B. The other terminal device  101 B indicates that it is now listening to the terminal device  101 ; e.g., by playing a suitable acoustic signal. 
     The PoC server  201  responds with message J 15  that is RTCP: Floor Granted. Then, the terminal device  101  indicates to the user that he or she can now talk; e.g., by playing a suitable acoustic signal. The PoC furthermore sends an SIP 202 message to the terminal device  101 . 
     Speech packets MN 1  coded at the terminal device  101  are transmitted as RTP: Talk bursts through the IMS core  203 A to the PoC server  201 . The PoC server  201  forwards them as speech packets MN 2 , transmitting them as RTP: Talk bursts to the other terminal device  101 B through the IMS core  203 B. The other terminal device  101 B receives the speech packets MN 2 , decodes them, and converts them to an audible form so that the user of the other terminal device  101 B can hear a reproduction of the speech coded by the terminal device  101 . 
     When talk button  167  is released at the terminal device  101 , the terminal device sends message J 21  that is RTCP: Floor release message. The PoC server  201  sends message J 23  that is RTCP: Floor idle message to the other terminal device  101 B. The other terminal device indicates to the user that the floor is now idle; i.e., that he or she may press the push button  167  of his or her terminal device  101 B. 
     The PoC server  201  responds with SIP NOTIFY, and the terminal acknowledges by sending SIP 200 OK message. The PoC server  201  responds once more by sending message J 25  that is RTCP: 
     Floor idle message. 
       FIG. 5  shows late media and manual answer for one-to-one communication using PoC. Now responsive to terminal device  101  detecting a pressing of talk button  167 , it sends message J 11  that is SIP INVITE to IMS core  203 A. The IMS core  203 A forwards the SIP INVITE to PoC server  201  that sends message J 13  that is SIP invite to IMS core  203 B. The IMS core  203 B forwards the SIP INVITE to the other terminal device  101 B, and passes SIP 100 Trying message to PoC server which forwards it through the IMS core  203 A to the terminal device  101 . 
     Upon receiving SIP INVITE, the other terminal device  101 B indicates that a talk is intented, such as by playing a suitable audible signal, and passes SIP 180 Ringing message through the IMS core  203 B, the PoC server  201 , and the IMS core  203 A to the terminal device  101 . The terminal device  101  alerts the user. 
     When a user of the other terminal device  101 B accepts the talk, such as by pressing a suitable button, the other terminal  101 B transmits SIP 200 OK message through the IMS core  203 B to the PoC server  201  which then sends message J 15  which is RTCP: Floor granted message to the terminal device  101 . The SIP 200 OK is furthermore passed to the terminal device  101 , after which the terminal device  101  alerts the user. Some acknowledgements and other SIP messages furthermore may be transmitted. The transmission of speech packets in messages MN 1  and MN 2  nevertheless takes place in a very similar manner than in the example discussed with reference to  FIG. 4 . 
       FIGS. 6A and 6B  illustrate possible structures of the message carrying geographical location information. The message can be J 11  (signalling from terminal device  101  to the PoC server  201  that a talk button  167  has been pressed), M 11  (any speech packet or particularly the first speech packet from the terminal device  101 ), J 13  (signalling from PoC server  201  to the other terminal device  101 B that a talk button  167  has been pressed at the terminal device  101 ), or M 12  (any speech packet or particularly the first speech packet from the PoC server  201  to the other terminal device  101 B). 
     The first terminal device  101  finds out its geographical location  65 . For doing this, it may use any suitable locationing method. Currently, terminal devices with assisted Global Positioning System A-GPS receivers are under development. A-GPS enables quick &amp; accurate location finding for the terminal device. 
     When the user of the first terminal device  101  pushes the talk button  167  in order to use the push-to-talk service, the first terminal device  101  requests the network for a permission to speak, and finally the push-to-talk message is generated by coding microphone input. The request for a permission to speak (message J 11 ) or any of the speech messages (MN 1 , especially M 11 ) may include the geographical location information  65 . 
     As shown in  FIG. 6A , the push-to-talk message J 11 , M 11 , J 13 , or M 12  may include a flag  63  “location information present” in the header field  61  indicating that the geographical location  65  follows. As an alternative, as illustrated in  FIG. 6B , the least-significant bits of the speech message  64  having coded speech may be used to indicate the geographical location  65 . The latter possibility enables a proprietary solution. 
     The other terminal device  101 B receives the push-to-talk message. After checking the flag  63  in the header field  61  or the least significant bits  65 , an application, such as the PoC application  165 , extracts the geographical location information  65 . 
     The other terminal device  101 B knows its own geographical location  65 B. 
     The other terminal device  101 B compares its own geographical location  65 B with the geographical location  65  of the terminal device  101 . Information based on a comparison result is shown to the user of the other terminal device  101 B. This information may include any of the following: direction of the terminal device  101  (may require use of a digital compass in the other terminal device  101 B); distance of the terminal device  101  from the other terminal device  101 B; show on a map the geographical location  65  of terminal device  101  vs. its own geographical location  65 B; or just displaying the geographical location  65  of terminal device  101  vs. its own geographical location  65 B. 
     It is by no means necessary that the geographical location  65  is received as such at the other terminal device  101 B. The other terminal device  101 B may transmit, such as by responding to any one of messages J 13  or MN 2  (particularly M 12 ) its own geographical location  65 B to a network unit; e.g., to the PoC server  201  which then computes the difference and transmits information based thereon to both the terminal device  101  and the other terminal device  101 B. 
     The terminal device  101 , for example, in one of its applications, such as the PoC application  165 , may have a settings menu for setting a “push-to-talk” item, under which a user can tick on/off the following items: 
     send own location with push-to-talk; and 
     show talking party&#39;s direction/location. 
     In other words, the user sending his or her own location has full control over whether or not the location is to be sent or, as described above, the parents or employer, for example, can control the transmission of the geographical location information. 
     Although the present invention has been described with reference to specific embodiments, those of skill in the art will recognize that changes may be made thereto without departing from the spirit and scope of the present invention as set forth in the hereafter appended claims.