Abstract:
Transmissions sent on a multicast broadcast multimedia service control channel (MCCH) to a mobile terminal are determined to be successfully received by signalling the expected number of messages within the transmission; and terminating receipt of the MCCH only when the number of messages received is equal to the number of messages signalled.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on and hereby claims priority to United Kingdom Patent Application No. 0502473.2 filed on Feb. 8, 2005, the contents of which are hereby incorporated by reference. 
     BACKGROUND 
     Described below is a method of determining successful receipt at a mobile terminal in a communication system, in particular for second and third generation mobile phone systems, such as Universal Mobile Telecommunications System Terrestrial Radio Access Network (LITRAN), offering multicast broadcast multimedia services (MBMS) or other broadcast services. 
     Broadcast services, such as MBMS which is standardized in radio access network (RAN), are becoming more and more important for mobile communication networks. However, a UE receiving messages on an MBMS control channel has no way of determining whether it has received safely all the messages in a transmission that it needs. 
     SUMMARY 
     The method of determining successful receipt at a mobile terminal of transmissions sent on a multicast broadcast multimedia service (MBMS) control channel (MCCH) described below includes signalling the expected number of messages within the transmission; and terminating receipt of the MCCH only when the number of messages received is equal to the number of messages signalled. 
     Preferably, the expected number of messages signalled is the total number of neighbor cell messages. 
     Preferably, the total number of neighbor cell messages is signalled in an MBMS modified services information message. 
     The total number of neighbor cell messages may be the number of neighbor cells in the transmission or the number of neighbor cells in the transmission associated with each service. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects and advantages will become more apparent and more readily appreciated from the following description of an example of a method of determining successful receipt at a mobile terminal of transmissions sent on an MBMS control channel (MCCH), taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a block diagram illustrating the method described below; and, 
         FIG. 2  is a message transmission diagram illustrating the neighbor cell messages received in the method of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made in detail to the preferred embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
     In order to ensure that a mobile terminal or UE knows that it has received all messages due to it, specifically the number of MBMS neighbor cell point to multipoint (p-t-m) radio bearer (RB) information messages, the number of neighbor cells is signalled in the 3 GPP MBMS control signalling. 
     Transmissions on the 3GPP MBMS control channel (MCCH) consist of a number of messages. An MCCH transmission will contain an MBMS modified services information message and an MBMS unmodified services information message. It may also contain an MBMS general information message, an MBMS common p-t-m RB message, an MBMS current cell p-t-m RB message and one or more MBMS neighbor cell p-t-m RB messages (one message per neighbor cell). 
     A UE that is required to receive an MBMS p-t-m bearer for an MBMS service must continue to receive the MCCH transmissions until it has received the MBMS common p-t-m RB message, the MBMS current cell p-t-m RB message and all MBMS neighbor cell p-t-m RB messages that contain information relating to the service. Messages are received from the transmissions sequentially. It is not possible for the UE to detect that it has failed to receive a message, so a mechanism is needed in order that the UE knows that it has received all of the neighbor cell messages that it requires. 
     In one embodiment the total number of neighbor cells (equivalent to one message each) in the transmission is signalled in an MCCH message. For example, the number may be signalled in the MBMS modified services information message or the MBMS common p-t-m RB message, or the MBMS current cell p-t-m RB message. 
     In another embodiment, the total number of neighbor cells (equivalent to one message each) is signalled in the transmission associated with each service in an MCCH message. An example of this is signalling in the MBMS current cell p-t-m RB message. 
     A UE that has received one of these parameters (only one would be signalled) would be able to compare the number of neighbor cell messages that it has received with the total number indicated in the signalling and identify if it has received all of the information that it requires. It can then stop receiving the MCCH. 
       FIG. 1  illustrates an example of a number of neighbor cells around a UE, from some of which NB2, NB4 and NB5 a UE, UE1 will receive an MBMS service transmission which the UE will combine with an MBMS transmission from the controlling node B, NB1. As shown in  FIG. 2 , a control transmission M1 from the controlling node B, NB1 to UE1 is split up into the messages 1 to 5, including an MBMS modified services information message 1; an MBMS unmodified services information message 2, an MBMS general information message 3, an MBMS common p-t-m RB message 4, and an MBMS current cell p-t-m RB message 5. In addition the transmission includes MBMS neighbor cell p-t-m RB messages, one message per neighbor cell, from neighbor cells NB2, message M2; NB4, message M4 and NB5, message M5. As explained above, a transmission does not always include all of the message types given in this example and the number signalled is adapted according to which messages are actually present in the transmission. 
     A description has been provided with particular reference to preferred embodiments thereof and examples, but it will be understood that variations and modifications can be effected within the spirit and scope of the claims which may include the phrase “at least one of A, B and C” as an alternative expression that means one or more of A, B and C may be used, contrary to the holding in  Superguide v. DIRECTV,  358 F3d 870, 69 USPQ2d 1865 (Fed. Cir. 2004).