Abstract:
A data receiving device ( 2   a ) is arranged to run a media guide application through which a user may access a service provided over broadcast network ( 3 ). Should reception of the service be interrupted, for example, by an incoming telephone call over telecommunications network ( 4 ), the data receiving device ( 2   a ) operates in a first resource saving mode where data is received by receiver ( 11 ) but neither processed nor output. The received data may be stored for later output or simply discarded. The service can then be resumed, with minimal delay, by restarting processing and outputting of received data, as it is not necessary to reactivate or resynchronise the receiver ( 11 ). After operating in said first resource saving mode for a predetermined time period, the receiver ( 11 ) may be deactivated in order to further save power. Applications used in receiving, processing and/or outputting the received data, may be closed down following the expiry of one or more further predetermined time periods.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates to a receiving device and method for receiving data that is particularly suitable for reception of digital services over a wireless link.  
         [0002]     Proposed services for mobile terminals, such as news, entertainment or business services, require the transmission of content to one or more receiving devices. The content may include audio, video, multimedia, graphic or other data, such as music files or film clips. However, a considerable amount of data is required to provide such services, and the reception and processing of this data may place significant demands on the restricted power and memory capacities of a mobile terminal.  
         [0003]     In particular, a mobile terminal may be required to run an unrelated application while receiving a service. For example, where the mobile terminal comprises a telephone handset, it may be required to handle an incoming call while receiving a data stream or, alternatively, a user may wish to access an application such as a calendar or notepad etc. Applications that are local to the mobile terminal can be suspended, for example, by saving a set of current parameters for subsequent use in resuming the application. However, the suspension of a service received from an external source is more problematical as the service itself is not interrupted and transmission of the data stream continues. In this situation, a service receiving part of the mobile terminal may close down reception of the service but, should the user wish to return to the service, this may require data reception, processing and outputting applications to be set up and started again, causing delay and inconvenience. Alternatively, the mobile terminal may continue to receive and process the data stream while the unrelated application is running. This wastes power, particularly as a large proportion of the power consumption in such a mobile terminal is due to the demands of a receiver when receiving data transmissions, and may be problematical as mobile terminals are typically powered by a battery of limited capacity. In addition, the reception and processing of data also requires processing resources, including memory, and prevent sufficient resources being available for handling the unrelated application.  
       SUMMARY OF THE INVENTION  
       [0004]     According to a first aspect of the invention, a data receiving device comprises receiving means arranged to receive data from a broadcast network, processing means for processing the received data and output means for outputting processed data and is arranged to operate in a first resource saving mode in which the receiving means remain active but received data is not processed by the processing means and not outputted by the output means.  
         [0005]     The data receiving device may be arranged so that, when in the first resource saving mode, received data is discarded or saved in a memory without being processed or output. In this manner, resources within the data receiving device that would have been used for processing and outputting the received data, such as memory and processing time, are freed up for use by an unrelated application.  
         [0006]     A data receiving device arranged to save received data when in the first resource saving mode may be configured so that, following the expiry of a predetermined time limit, any further received data is discarded without being saved. The predetermined time limit may be set by a user of the data receiving device.  
         [0007]     As the receiving means remain active, should such a data receiving device, when operating in the first resource saving mode, be required to resume outputting received data, reactivation and resynchronization of the receiving means is not required. Therefore, processing and output of received data may be resumed with minimal delay.  
         [0008]     The data receiving may be configured to, after operating in said first resource saving mode for a first predetermined time period, operate in a second resource saving mode in which the receiving means is deactivated while the processing means and output means remain operational. The deactivation of the receiving means reduces demand placed on a source supplying power to the receiving means.  
         [0009]     Such a data receiving device may further be configured to, after operating in the second resource saving mode for one or more further predetermined time periods, perform one or more of the following steps: deactivate an application for outputting processed data via the output means, close an IP session configured to handle the output data and/or remove a filter means arranged to extract selected data from the received data for processing. For example, the data receiving device may be arranged to, after a second predetermined period of time, deactivate an application for outputting data via the output means, close the IP session and remove the filter means. In another example, the receiving device may be arranged to perform these actions in two or more stages, each stage being carried out after the expiry of an associated further predetermined time period.  
         [0010]     The data receiving device may be configured to operate in the first resource saving mode following an interruption. An interruption may arise, for example, from the activation of an application in the data receiving device that is unrelated to reception of data from the broadcast network. The data receiving device may be arranged so that, in such a case, it operates in the first resource saving mode in response to a determination that insufficient resources are available for handling reception of data and the unrelated application. Where the data receiving device comprises a telephone transceiver arranged to transmit and receive data via a telecommunications network, an interruption may arise due to reception of an incoming telephone call from the telecommunications network.  
         [0011]     The data receiving device may be arranged to execute a media guide application for selectively accessing services provided over broadcast network. The media guide application may be configured to display and, if required, update a list of available services on a user interface of the data receiving device.  
         [0012]     The output means may comprise one or more of a display for outputting visually displayable data and audio output means. The audio output means may be integral to the data receiving device or arranged to provide data to an external speaker, an earphone or headphones connected to, or in wireless communication with, the data receiving device.  
         [0013]     The invention also provides a communication system comprising a broadcast network and one or more receiving devices as described above. The communication system may further include a bi-directional telecommunications network, where at least one of the one or more data receiving devices comprises a telephone transceiver arranged to transmit and receive data via said telecommunications network.  
         [0014]     According to a second aspect of the invention, a method of receiving data comprises receiving data from a broadcast network, processing the received data, outputting the processed data and, in response to an interruption, proceeding in a first resource saving mode by continuing to receive data from the broadcast network but not processing and not outputting said received data.  
         [0015]     The received data may be stored or simply discarded. Where the received data is stored, the method may comprise discarding data received following the expiry of a predetermined time limit.  
         [0016]     The method may further comprise, after proceeding in said first resource saving mode for a first predetermined time period, proceeding in a second resource saving mode in which no data is received from the broadcast network. The method may comprise operating in one or more further resource saving modes following the expiry of one or more corresponding further predetermined time periods.  
         [0017]     The step of receiving data from the broadcast network may comprise filtering the received data in order to discard unwanted data. The method may comprise removing a filter arranged to perform said filtering step after operating in a further resource saving mode following the expiry of a further predetermined time period.  
         [0018]     The method may further comprise displaying a list of services provided over the broadcast network and, optionally, updating said list of services and displaying an updated list.  
         [0019]     This aspect also provides a computer program comprising instructions that, when run on processing means within a data receiving device, cause the data receiving device to perform said method. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     In order that the invention may be more fully understood, embodiments thereof will now be described by way of example, with reference to the accompanying drawings in which:  
         [0021]      FIG. 1  is a schematic block diagram of a mobile communications system comprising a digital broadcast network according to one embodiment of the invention;  
         [0022]      FIG. 2  is a schematic block diagram of a mobile terminal configured to receive data from the digital broadcast network in the communication system of  FIG. 1 ;  
         [0023]      FIGS. 3 and 4  show a flowchart depicting a procedure performed by the mobile terminal of  FIG. 2 , for receiving and displaying content, according to one embodiment of the invention;  
         [0024]      FIG. 5  depicts an example welcome page to an ESG application that may be displayed by the mobile terminal of  FIG. 2 ;  
         [0025]      FIG. 6  depicts an example service menu that may be displayed by the mobile terminal of  FIG. 2 ;  
         [0026]      FIG. 7  depicts an example notification message that may be displayed by the mobile terminal of  FIG. 2 ; and  
         [0027]      FIG. 8  is a flowchart showing part of a procedure for receiving and displaying content according to another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0028]      FIG. 1  illustrates schematically a communication system  1  in which mobile user equipment in the form of mobile terminals, such as telephone handsets  2   a ,  2   b , are configured to receive transmissions from a digital broadcast network  3  which, in this particular example, is a DVB-T network, and to enable communication through a public land mobile network (PLMN)  4 . The digital broadcast network  3  transmits content such as audiovisual content, visually displayable data, audio files or data files to the handsets  2   a ,  2   b.    
         [0029]     The content is obtained from data stream servers  5   a ,  5   b  in Internet protocol (IP) so that the network can provide an IP Datacast (IPDC) service over the digital broadcast network  3 . Two such servers  5   a ,  5   b  are shown by way of example although in practice there may be many more. The stream servers  5   a ,  5   b  supply content in the form of IP datagrams. The datagrams are embedded into multi-protocol encapsulation (MPE) that are incorporated into MPEG-2 transport stream (TS) packets for broadcast by the digital broadcast network  3 . For further details reference is directed to ETSI EN 301 192 V1.3.1 (2003-01) “Digital Video Broadcasting (DVB) DVB specification for data broadcasting” Section 7.  
         [0030]     The digital broadcast network  3  is cellular and antennae  6   a ,  6   b  and  6   c  serve individual cells of the network  3  at geographically spaced sites.  
         [0031]     The PLMN  4  may comprise any suitable 2 G, 2.5 G or 3 G network with antennae  7   a ,  7   b  that serve individual cells of the PLMN  4 . A communication channel 8 may be provided between the digital broadcast network  3  and the PLMN  4  to allow bi-directional communication between the networks  3 ,  4 , for example, for the interchange of service information.  
         [0032]      FIG. 2  illustrates the circuits of a terminal  2   a  by way of a simplified example, in which the terminal  2   a  includes first and second antennae  9 ,  10 , a receiver  11  and a transceiver  12 . The first antenna  9  and receiver  11  are configured to receive signals from the digital broadcast network  3 . The second antenna  10  and transceiver  12  are used to transmit and receive signals to and from the PLMN  4 . RF signal processing circuits, not shown, are provided for amplifying and demodulating signals received by the receiver  11  and transceiver  12 , together with processors, not shown, for channel de-coding and de-multiplexing.  
         [0033]     The terminal  2   a  also includes a controller  13 , a user interface  14 , memory  15 , a smart card reader  16 , a smart card  17  received in the smart card reader  16 , a coder/decoder (codec)  18 , a speaker  19  with a corresponding amplifier  20  and microphone  21  with an associated preamplifier  22 .  
         [0034]     The terminal  2   a  is powered by a rechargeable battery  23 .  
         [0035]     The user interface  14  comprises a display  24  and keypad  25 . The display  24  is configured with a resolution that is adequate for the display of images and video and may also be capable of displaying colour images.  
         [0036]     The controller  13  manages operation of the terminal under the direction of computer software stored in memory  15 , providing output for presentation on the display  24  and receiving user input from the keypad  25 .  
         [0037]     The terminal  2   a  has an electronic service guide (ESG), or media guide, application for displaying information relating to and providing access to services available over the digital broadcast network  3 . For example, programme information, such as channel lists, current programs, recently viewed programs and available channels, can be accessed by a user through a system of one or more menus. The ESG application allows the user to select a service, such as a programme to view, and manages the reception and output of content relating to the selected service. The information relating to services may be broadcast over the digital broadcast network  3  for storage in the memory  15  of terminal  2   a  and updated and rebroadcast as required.  
         [0038]     A procedure followed by an ESG application, according to one embodiment of the invention, will now be described with reference to  FIGS. 3 and 4 , beginning at step s 3 . 0 . The parts of  FIG. 3  shown with dotted lines relate specifically to another embodiment of the invention, to be described later.  
         [0039]     The ESG application is activated and, in this example, a welcome page is displayed on display  24  (step s 3 . 1 ), which provides a number of options to the user, including display of one or more menus of available services. An example welcome page is shown in  FIG. 5 , in which options for viewing menus of different types of services, such as TV and radio channels, games, chatrooms and software updates are provided, along with an option to exit the ESG application.  
         [0040]     In other embodiments of the invention, the welcome page may include a logo or other data associated with the ESG application and/or application provider instead of, or in addition to, the options shown in  FIG. 5 . Alternatively, another page or view within the ESG application, such as a sub-menu or a page relating to updated information or advertising a programme, may be displayed in place of a welcome page. In each case, a user can access one or more menus of services by selecting an appropriate option provided on the displayed page.  
         [0041]     The user may select an option from the welcome page, or other displayed page, using keypad  25 . In this particular example, a focus region  26  acts as a cursor. The user can select an option by moving the focus region  26  between the various options in the welcome page, using keypad  25 , and pressing a designated key to select an option highlighted by the focus region  26 .  
         [0042]     When a selection is received (step s 3 . 2 ), the controller  13  determines whether the user has requested to view a menu (step s 3 . 3 ). If so, the appropriate menu is displayed (step s 3 . 4 ), providing the user with a list of available services. In this particular example, a TV channels menu is selected and displayed as shown in  FIG. 6 , which lists programmes currently being transmitted over the digital broadcast network  3 . The menu may include programme information, such as titles and times of transmission. The menu may be updated periodically from the ESG information stored by the terminal  2   a . If it is no longer possible to maintain the menu, for example, if the displayed menu becomes obsolete, the ESG application may notify the user and/or return to displaying the welcome page on display  24  from which the user can select another menu to view or, alternatively, exit the ESG application.  
         [0043]     The user may select a service from a displayed menu. In response to a selection (step s 3 . 5 ), a stream player is activated (step s 3 . 6 ) for outputting data from the service through the display  24  and, if required, speaker  19  and/or another audio output means, such as headphones or external speakers connected to, or in communications with, the terminal  2   a . An application for de-encapsulating the extracted TS packets in order to retrieve the original IP datagrams is activated and an IP session for handling the IP datagrams is created (step s 3 . 7 ). A filter is then created (step s 3 . 8 ) at the receiver  11  for extracting TS packets relating to the selected service from a data stream broadcast over the digital broadcast network  3 .  
         [0044]     The receiver  11  is then switched into a reception mode (step s 3 . 9 ) for receiving the data stream and is synchronised with the digital broadcast network  3 . The terminal  2   a  can then receive and output content relating to the selected service (step s 3 . 10 ) through its user interface  14 .  
         [0045]     If reception of the service is not interrupted (step s 3 . 11 ), the reception and output of content (step s 3 . 10 ) continues until reception is to end (step s 3 . 12 ). For example, a service may be completed or an indication that the user no longer wishes to access the service may be received via keypad  25 . The controller  13  deactivates the receiver  11  (step s 3 . 13 ) and sends a “Remove Filters” command to the receiver  11 , in response to which the filter is deleted (step s 3 . 14 ). The IP session is closed (step s 3 . 15 ) and the stream player deactivated (step s 3 . 16 ).  
         [0046]     The controller  13  then determines whether the most recently displayed menu, displayed at step s 3 . 4 , remains up to date (step s 3 . 17 ). If so, the menu is displayed (step s 3 . 4 ). The user may then access another service from the menu or, alternatively, the ESG welcome page. If the ESG welcome page (step s 3 . 1 ) is displayed, the user may access another service via a second menu or, alternatively, exit the ESG application, completing the procedure (steps s 3 . 2 , s 3 . 3 , s 3 . 19 ).  
         [0047]     If it is determined that the menu is not up to date (step s 3 . 17 ), the controller  13  ascertains whether the menu can be updated or recovered using service information stored in memory  15  and, in response to a positive determination, displays an updated or recovered menu (step s 3 . 4 ), from which the user may access another service or the ESG welcome page. However, if it is not possible to update or recover the menu (step s 3 . 17 ), for example, where the menu has become obsolete, a notification message may be displayed to inform the user of this, before displaying the welcome page (step s 3 . 1 ). In either case, the user may access another service or exit the application as described (e.g. steps s 3 . 2 , s 3 . 3 , s 3 . 19 ).  
         [0048]     As noted above, the power consumption of the receiver  11 , when receiving data (steps s 3 . 10  to  3 . 12 ), may form a considerable proportion of the demand placed on the battery  23 . Moreover, the controller  13  may be required to utilise and/or reserve a considerable proportion of available memory  15  for processing the TS packets and outputting content, particularly as the incoming data stream may have a high bit-rate. Should the terminal  2   a  be required to perform an unrelated function while data is being received and output, such as handling an incoming telephone call over PLMN  4 , there may not be sufficient available resources available to accommodate both the ESG application and the unrelated function.  
         [0049]     A procedure followed when the reception and output of content (steps s 3 . 10  to s 3 . 12 ) is to be interrupted will now be described, with reference to an example situation in which the terminal  2   a  is required to handle an incoming telephone call. However, an interruption may also occur if the user activates an unrelated application on the terminal  2   a , for example, to inspect appointments stored using a calendar application, or where the user requests interruption of reception of the service in order to perform another activity away from the terminal  2   a  or while moving through an area in which the data stream cannot be received.  
         [0050]     On reception of the incoming call (step s 3 . 11 ), the controller  13  alerts the user to the incoming call, for example, using an audio notification and/or by displaying a notification message on the display  24 . An example notification message  27  is shown in  FIG. 7 . The notification message  27  requests the user to indicate whether to proceed with the call and, therefore, whether access to the service is to be suspended (step s 4 . 1 ). The user can respond to this request, selecting an option  28 ,  29  by positioning the focus region  26  using keypad  25  and pressing a designated key to select the highlighted option  28 . In this particular example, the notification message  27  covers most or all of the display area and so the output of content through the stream player may be suspended while the notification message  27  is displayed. Alternatively, the controller  13  may be arranged to suspend output of visual content through the stream player while allowing audio output to continue.  
         [0051]     In other embodiments of the invention, the notification message displayed over a smaller area of the display  24 , for example, displayed over the output visual content and/or displayed in the form of a small icon. The notification message may also be displayed outside a frame within which the visual content is displayed. In these cases, the notification message or audio notification may be configured so that the user can continue viewing content while the notification message is displayed.  
         [0052]     Where the interruption is caused by the running of another application, unrelated to the reception of data, a similar notification message, not shown, may be displayed in order to allow the user to indicate whether or not data reception is to be suspended.  
         [0053]     The controller  13  initializes a timer in order to monitor the time t elapsed from the display of the notification message  27  (step s 4 . 2 ). A predetermined period of time t 1  is allowed for receipt of an indication from the user (step s 4 . 3 ). Meanwhile, the various components and processes required for receiving, filtering, processing and outputting received data, including the receiver  11 , filter, IP session and stream player, remain active. In this example, time period t 1  is 4 seconds, although t 1  may be set as a shorter or longer time period, for example, up to 10 seconds, as required.  
         [0054]     If, before the expiry of time period t 1  (step s 4 . 4 ), that is, t&lt;t 1 , the user indicates that the service is to continue (step s 4 . 5 ), the unrelated application is terminated or suspended as appropriate (step s 4 . 6 ). In this example, the incoming telephone call is rejected or diverted to a voicemail service. The data reception and output procedure continues as before (steps s 3 . 10  to s 3 . 12 ).  
         [0055]     On the other hand, if the user wishes to suspend access to the service (step s 4 . 5 ), in order to answer the incoming call, or if the controller  13  determines that time period t 1  has expired (step s 4 . 4 ), the ESG application operates in a resource saving mode.  
         [0056]     When in resource saving mode, the receiver  11  continues to receive data but the received TS packets are discarded (step s 4 . 7 ), without extracting or processing them, in order to reduce processing and memory requirements. The stream player application continues running in the background, while the incoming call is handled.  
         [0057]     In another embodiment of the invention, the controller  13  may automatically perform steps s 4 . 2 , s 4 . 7  without requesting confirmation from the user or providing an opportunity to terminate or suspend the unrelated application, for example, if the controller  13  determines that the available resources, such as power, memory and/or processing power, are insufficient to accommodate the service and the other application, or if the unrelated application is executed in response to an explicit request from the user. In such an embodiment, the controller  13  automatically initializes the timer (step s 4 . 2 ) in response to the interruption and send an alert, such as an “Overloaded” message, to the receiver  11 . On receipt of the alert, the receiver  11  begins discarding received TS packets (step s 4 . 7 ), thereby freeing processing capacity for use in handling the telephone call.  
         [0058]     The timer continues to monitor the time t elapsed and is used to determine whether this exceeds further predetermined time periods t 2  and t 3 . In this particular example, t 2  is 120 seconds and t 3  is 300 seconds however, in other embodiments of the invention, t 2  and t 3  may be set at other values, if required. For example, t 2  may be set at 60 seconds. The values of the second and third time periods t 2 , t 3  may also be set in dependence on the type of application causing the interruption. In this example, where the interruption is a telephone call, it is possible that the duration of the call may be extremely short, for example, less than one minute, in which case the values above would be suitable. However, if the interruption is caused by an application that is activated by the user, different second and third time periods t 2 , t 3  may be appropriate. For example, if the interruption is caused by the activation of a web browser within the mobile terminal  2   a  by the user, for example, by following a link provided in the ESG application in order to browse related content, the controller  13  may set the duration of one or both of the second and third time periods t 2 , t 3  at longer periods, for example, 200 seconds and 600 seconds respectively.  
         [0059]     If the telephone call is completed before expiry of time period t 2 , that is, t 1 ≦t≦t 2 , the user&#39;s access to the service may be resumed (step s 4 . 8 ) in the following manner. The ESG application resumes normal operation. The resumption may be automatic on completion of the unrelated application, that is, when the user ends the telephone call or closes a window presented on display  24  that is associated with it, or by the user manually reactivating the ESG application from, for example, an applications menu displayed by the terminal  2   a . The controller  13  simply restarts processing of received TS packets and output of content (steps s 3 . 10  to s 3 . 12 ). As the receiver has continued to receive TS packets from the digital broadcast network  3  (step s 4 . 7 ) throughout time period t 2 , access to the service may be achieved rapidly and straightforwardly, as it is not necessary to resynchronise the receiver  11  with the digital broadcast network  3 .  
         [0060]     However, if access to the service is not resumed before time period t 2  has elapsed (step s 4 . 9 ), i.e. t&gt;t 2 , the receiver  11  is automatically switched into an inactive mode (step s 4 . 10 ) to conserve power, for example, on receipt of a “Sleep” command sent by the controller  13 .  
         [0061]     Where time period t 2  has expired but time period t 3  has not yet elapsed, that is, t 2 ≦t≦t 3 , access to the service may be resumed (step s 4 . 11 ) as follows. As in the previous scenario, the ESG application may resume normal operation automatically on completion of the unrelated application, for example, on disconnection of a telephone call with a duration greater than time period t 2  but less than time period t 3 , or by the user selecting the ESG application from the applications menu. The receiver  11  is then reactivated, on receipt of a “Wakeup” command from the controller  13 , and resynchronised with the network (step s 3 . 9 ). The reception and output of content then continues as before (steps s 3 . 10  to s 3 . 12 ).  
         [0062]     If access to the service is not resumed before time period t 3  expires (at step s 4 . 12 ), i.e. t&gt;t 3 , the stream player is deactivated (step s 3 . 14 ), the IP session is closed (step s 3 . 15 ) and the filters are removed (step s 3 . 16 ). The menu is then displayed (step s 3 . 4 ), following any necessary updating or recovery (step s 3 . 17 , s 3 . 18 ).  
         [0063]     Alternatively, if the menu has become obsolete or out of date and cannot be updated or recovered (steps s 3 . 17 , s 3 . 18 ), the welcome page is displayed (step  3 . 1 ). The user may then access another service or exit the ESG application as described above.  
         [0064]     In another embodiment of the invention, the ESG application may follow another procedure will now be described with reference to  FIGS. 3 and 8 , in which the various components and processes required for reception of the service from the DVB-type network  3  are deactivated in stages.  
         [0065]     Through this procedure, a service can be selected and accessed as shown in steps s 3 . 0  to s 3 . 12  and, in response to an interruption, the procedure follows steps s 8 . 1  to s 8 . 10  that correspond to steps s 4 . 1  to s 4 . 10  as described in relation to the previous embodiment. In other words, following an interruption, confirmation is requested from the user that the service is to be suspended (step s 8 . 1 ) and a timer is initialized (step s 8 . 2 ).  
         [0066]     The timer is used to determine whether the time t elapsed from the display of the notification message (step s 8 . 1 ) or, where the service is to be suspended automatically, without confirmation from the user, from the interruption, exceeds one or more predetermined time periods t 1  to t 5 . In this particular example, t 1  is set to 4 seconds and t 2  to t 5  set to 120 seconds, 300 seconds, 450 seconds and 600 seconds respectively, although the chosen time periods t 1  to t 5  may be set at other values in other embodiments of the invention and/or in dependence on the cause of the interruption, as described above in relation to the first embodiment.  
         [0067]     If the user wishes to suspend the service (step s 8 . 5 ) or if time period t 1  expires before the user has responded to a notification message (step s 8 . 4 ), data continues to be received by receiver  11  but is discarded without being processed or output (step s 8 . 7 ). Following the expiry of second time period t 2 , the receiver  11  may be deactivated in order to conserve power (step s 8 . 10 ). The service may then be resumed (step s 8 . 11 ), where t 2 ≦t≦t 3 , either automatically on completion of an application causing the interruption or on receipt of a request for resumption from the user. The receiver  11  is then reactivated and synchronised with the DVB-type network  3  (step s 3 . 9 ) and data reception resumes (steps s 3 . 10  to s 3 . 12 ).  
         [0068]     However, if the service is not resumed before the expiry of third time period t 3  (step s 8 . 12 ), that is, t&gt;t 3 , the filter is deleted by sending a “Remove filters” command from the controller  13  to the receiver  11  (step s 8 . 13 ). If the user then requests resumption of the service (step s 8 . 14 ), before the expiry of the fourth time period t 4 , i.e. t 3 ≦t≦t 4 , a new filter is created (step s 3 . 8 ), the receiver  11  is activated and resynchronised (step s 3 . 9 ) and data reception continues (steps s 3 . 10  to s 3 . 12 ).  
         [0069]     Should the fourth time period t 4  expire (step s 8 . 15 ) without resumption of the service, the IP session is closed (step s 8 . 16 ). If the user subsequently wishes to return to the service (step s 8 . 17 ) before the expiry of fifth time period (step s 8 . 18 ), i.e. t 4 ≦t≦t 5 , a new IP session must be created (step s 3 . 7 ), along with a new filter (step s 3 . 8 ) and reactivation and resynchronization of the receiver  11  (step s 3 . 9 ) before data reception resumes (steps s 3 . 10  to s 3 . 12 ).  
         [0070]     If the service is not resumed before the fifth time period t 5  expires (step s 8 . 18 ), the stream player is deactivated (step s 8 . 19 ).  
         [0071]     Following deactivation of the stream player (step s 8 . 19 ), the menu, following any necessary updating or recovery (steps s 3 . 17 ,  3 . 18 ) or welcome page is displayed (step s 3 . 4  or s 3 . 1 ) as described in relation to the first embodiment. The user may then access another service or exit the ESG application, completing the procedure (step s 3 . 19 ).  
         [0072]     In the above described embodiments, the terminal  2   a  is configured so that received data is discarded while t 1 ≦t≦t 2 . However, in another embodiment of the invention, the terminal  2   a  may be arranged so that, instead of being discarded, received data is stored in memory  15 . This allows the user to view and/or listen to content broadcast during the interruption, for example, if an interruption occurs towards the end of a scheduled programme or during broadcast of a live event. The terminal  2   a  may be arranged so that, following suspension, i.e. in response to expiry of first time period t 1  at step s 4 . 4  or reception of an indication from the user that the service is to be suspended at step s 4 . 5 , received data is stored without being processed or output up to a time limit t′. Thereafter, received data is discarded (step s 4 . 7 ) until the service is resumed (step s 4 . 8 ) or time period t 2  expires (step s 4 . 9 ). The time limit t′ may be pre-set by the controller  13  or set manually by the user when confirming suspension of the service (step s 4 . 5 ).  
         [0073]     Although, in the procedure shown in  FIG. 8 , time periods t 2 , t 3 , t 4  and t 5  are of different lengths, two or more of these time periods t 2  to t 5  may be set to identical values, if required.  
         [0074]     While the embodiments described above relate to services broadcast over a DVB-T network  3 , the invention may be implemented in systems comprising other types of digital broadcast network, for example, networks according to DVB-S, DVB-H, Integrated Services Digital Broadcasting (ISDB) or Advanced Television Standards Committee (ATSC) standards.  
         [0075]     Furthermore, the invention has been described by way of an example in which IPDC services are provided to mobile terminals  2   a ,  2   b . However, the invention may be used in the distribution of content and digital rights to personal digital assistants (PDAs), laptop computers or other devices arranged to receive data from a digital broadcast network in addition to, or instead of, one or more mobile terminals  2   a ,  2   b.