Abstract:
A method of providing a multimedia multicast service in a digital wireless communication network, the network having a network controller for controlling of at least one base station, comprising establishing a single data stream from the network controller to the base station for transmitting of multimedia data, by means of a single lub link or transport bearer and establishing a separate communication link and a separate data queue for each user equipment in a radio cell of the base station which requests the multimedia data.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention is based on a priority application EP03292005.0 which is hereby incorporated by reference.  
         [0002]     The present invention relates to the field of telecommunications, and more particularly without limitation, to multimedia multicast and multimedia broadcast services.  
       BACKGROUND AND PRIOR ART  
       [0003]     Point to multi point services exist today which allow data from a single source entity to be transmitted to multiple end points. These services are expected to be used extensively over wireless networks. In particular there is a strong interest to provide multimedia broadcast/multicast service over 3G networks.  
         [0004]     The multimedia broadcast/multicast service (MBMS) which is considered for the universal mobile telecommunications systems (UMTS) is a unidirectional point-to-multi point bearer service in which data is transmitted from a single source entity to multiple recipients. 3GPP has defined two modes of operation: (i) the broadcast mode and (ii) the multicast mode.  
         [0005]     The broadcast mode is a unidirectional point-to-multi point transmission of multimedia data from a single source entity to all users in a broadcast area or areas. Data is transmitted to broadcast areas as defined by the network. A broadcast service received by a user equipment involves one or more successive broadcast sessions. A broadcast service might, for example, consist of a single on-going session, e.g. a media stream, or may involve several intermittent sessions over an extended period of time, e.g. messages. An example of a service using the broadcast mode could be advertising or a welcome message to the network. As not all users attached to the network may wish to receive these messages then the user shall be able to enable/disable the reception of these broadcast services on his user equipment. A disadvantage of the broadcast mode is that power control cannot be performed individually for the user equipment.  
         [0006]     The multicast mode enables the unidirectional point-to-multi point transmission of multimedia data from a single source point to a multicast group in a multicast area. Like in the broadcast mode data is transmitted to multicast areas as defined by the network. In the multicast mode there is the possibility for the network to selectively transmit to cells within the multicast area which contain members of a multicast group. Such multicast services allow unidirectional point-to-multi point transmission of multimedia data, e.g. text, audio, picture, video, from a single source point to a multicast group in a multicast area. An example of a service using the multicast mode could be an information service for which a subscription is required, e.g. a football results service for which a subscription is required.  
         [0007]     In the multicast mode data is streamed in parallel from the radio network controller to the node-B for transmission to the user equipment. For further technical information on the multimedia broadcast/multicast service (MBMS) reference is made to ETSI TS 122 146 V5.2.0(2002-03) and 3GPP TS 25.346 V1.3.0(2003-01) the entirety of which is herein incorporated by reference.  
         [0008]     Broadcast and multicast services for other digital wireless communication networks, such as digital TV, DVD-T and DVB-M are also considered in “Broadcast and Multicast Services in Mobile Networks, Ahmavaara K., Jolma P. and Raivio Y.” (http://www.nokia.com/downloads/aboutnokia/research/library/mobile_networks/MNW 9.pdf)  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention provides a multimedia multicast service method for a digital wireless communication network, such as a UMTS-type network. Such a network has network controllers for controlling of base stations. In the case of UMTS the network controllers are referred to as “radio network controllers” (RNCs) whereas the base stations are referred to as “node-Bs”.  
         [0010]     Multimedia data of the multimedia multicast service is transmitted from the network controller to the base station by means of a single data stream. This compares to the 3GPP MBMS where multiple redundant data streams are established between the RNC and the node-B. This way the present invention enables to make better usage of the available data transmission capacity between the network controller and the base station.  
         [0011]     In the multicast mode when using point to point beareres a separate communication link and a separate data queue is established for each user equipment in a radio cell of the base station which requests the multimedia data. This enables to separately control the transmission power of each one of the communication links.  
         [0012]     In accordance with a preferred embodiment of the invention the data stream from the network controller to the base station is transmitted via a single lub link. The UTRAN lub interface is as such known from the prior art and is specified in 3G TS 25.430 V3.0.0(2000-01), pages 1 to 21. In accordance with the 3GPP MBMS specification multiple lub links or transport bearers are required for transmitting of multiple data streams in parallel from the RNC to the node-B. In contrast the present invention enables to use a single lub link for transmitting of the single data stream containing the multimedia data.  
         [0013]     In accordance with a further preferred embodiment of the invention high speed downlink packet access (HSDPA) is used in order to realize the separate data queues for the multicast service. HSDPA is a packet-based data service which is as such known in the prior art and which has been specified by 3GPP.  
         [0014]     In accordance with a further preferred embodiment of invention the requests of the user equipment for multimedia service are signaled to the network controller. The network controller controls the base station which services the respective user equipment to establish respective separate data queues for streaming of the multimedia data to the user equipment.  
         [0015]     A further aspect of the invention is the provision of multimedia broadcast services and multicast in a digital wireless communication network by means of point to multipoint bearers. As in the multicast mode a single data stream between the network controller and the base station is established for transmitting of the multimedia data. Again this can be implemented by using a single lub link for the single multimedia data stream.  
         [0016]     The multimedia data stream is distributed to a plurality of user equipment in the same radio cell by establishing a single data queue for the plurality of user equipment. In other words a separate data queue is established for each radio cell which is serviced by the base station. Again HSDPA can be used for realization of the data queue.  
         [0017]     In accordance with a further aspect of the invention the usage of point to point or point to multipoint is selected depending on the number of active user equipment per radio cell or per base station. If the number of user equipment is below a threshold value point to point is selected by the network controller or the node-B. If the number of user equipment which is serviced by the base station surpasses a certain threshold level the network controller switches the base station to point to point. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]     In the following preferred embodiments of the invention will be described in greater detail by making reference to the drawings in which:  
         [0019]      FIG. 1  is a block diagram of a telecommunication system with a node-B in multicast mode,  
         [0020]      FIG. 2  is a block diagram of a telecommunication system with a node-B in multicast mode servicing user equipment in two different radio cells,  
         [0021]      FIG. 3  is a block diagram of a telecommunication system with a node-B in a broadcast mode,  
         [0022]      FIG. 4  is a flow chart being illustrative of the selection of the point to point or point to multipoint multicast mode,  
         [0023]      FIG. 5  is a block diagram of a telecommunication system with a node-B in a hybrid broadcast/multicast mode. 
     
    
     DETAILED DESCRIPTION  
       [0024]      FIG. 1  shows a block diagram of wireless telecommunication system, such as a UMTS-type system. Telecommunication system  100  has radio network controller (RNC)  102 . Radio network controller  102  has control module  104  for controlling node-B  106 .  
         [0025]     Node-B  106  has control module  108  for controlling the internal operation of node-B  106  and for receiving control commands from control module  104  of radio network controller  102 .  
         [0026]     Preferably the interface between radio network controller  102  and node-B  106  is based on the lub standard definition. The lub interface is a logical interface for the interconnection of Node-B and Radio Network Controller components of the UMTS Terrestrial Radio Access Network (UTRAN). The radio network control signaling between these nodes is based on the Node B application part (NBAP). The control commands from Radio Network Controller to the Node-B can be transmitted by using the signaling transport related to NBAP signaling across the lub Interface.  
         [0027]     Node-B  106  is coupled to antenna  110  for providing telecommunication services to user equipment (UE)  1 ,  2 ,  3  . . . .  
         [0028]     In operation server computer  114  is coupled to radio network controller  102  for providing multimedia data stream  116  to radio network controller  102 . For transmission of multimedia data stream  116  from server computer  114  to radio network controller  102  any suitable transmission medium, such as the Internet, can be utilized.  
         [0029]     A single lub link  118  is established between radio network controller and node-B  106  for transmission of multimedia data stream  116  from radio network controller  102  to node-B  106 . Control module  108  of node-B  106  receives a control command from control module  104  of radio network controller  102 . In response control module  108  controls node-B  106  to establish respective separate data queues  120 ,  122 ,  124 , . . . for each one of the active user equipment, i.e. UE 1 , UE 2 , UE 3 , . . . . Preferably each one of the data queues is d HSDPA queue.  
         [0030]     The data queues  120 ,  122 ,  124 , . . . serve to buffer multimedia data stream  116  for transmission via antenna  110  to the corresponding user equipment UE 1 , UE 2 , UE 3 , . . . Using of HSDPA in the multicast mode has the advantage that the transmission power can be controlled individually for each one of the user equipment.  
         [0031]     The present invention is particularly advantageous as it enables to use a single lub link  118  for transmission of multi-media data stream  116  from radio network controller  102  to node-B  106 . This way the transmission of multiple redundant multimedia data streams from radio network controller  102  to node-B  106  is avoided. Another advantage is that the point to point multi cast mode in which node-B  106  is operated in the example considered here enables to control the transmission power for each one of the multi cast communication links separately.  
         [0032]     If node-B  106  has HSDPA capability one implementation option is to enhance the MAC-hs functionality in node-B  106  by introducing a duplication function which duplicates multimedia data stream  116  which is received via the single lub link  118  and distributes it internally toward the user equipment specific data queues  120 ,  122 ,  124 , . . . , i.e. HSDPA priority queues.  
         [0033]      FIG. 2  shows telecommunication system  100  when node-B  106  provides multimedia point to point multi cast service to user equipment UE 1 , UE 2 , UE 3  in radio cell  112  as well as to user equipment UE 1 , UE 2 , UE 3  in another radio cell  126 . In this case control module  108  of node-B  106  receives a control command from control module  104  in order to establish separate data queues for each one of the user equipment in the respective radio cells within different MAC-hs entities  128  and  130 . MAC-hs entity  128  has data queues  120 ,  122 ,  124  for respective user equipment within radio cell  112 , i.e. UE 1 , UE 2 , UE 3 . Likewise data queues  132 ,  134 ,  136  are created in MAC-hs entity  130  for respective user equipment within radio cell  126 , i.e. UE 1 , UE 2 , and UE 3  of radio cell  126 . Again it is preferred to implement the data queues as HSDPA priority queues.  
         [0034]      FIG. 3  shows telecommunication system  100  when node-B  106  is in a point to multipoint transmission mode. In this case control module  108  of node-B  106  receives a control command from control module  104  of radio network controller  102  to establish separate data queues  138 ,  140  for respective radio cells which are covered by node-B  106 , i.e. radio cells  112  and  126 , respectively. Preferably data queues  138  and  140  are implemented as HSDPA priority queues.  
         [0035]     It is to be noted that as in the point to point multicast mode (c.f.  FIG. 1  and  FIG. 2 ) only a single lub link  118  is established between radio network controller  102  and node-B  106  for transmission of multimedia data stream  116 . This way efficient usage is made of the available bandwidth resources.  
         [0036]      FIG. 4  shows a corresponding flowchart. In step  200  data transmission is started in the point to point multicast mode as the number of user equipment requesting multimedia services is relatively low. Hence a dedicated data queue is created in the node-B which services the respective user equipment as explained in detail above with reference to  FIGS. 1 and 2 .  
         [0037]     In step  202  it is checked if the number of user equipment per radio cell requesting the multimedia service surpasses a predefined threshold level. If this is not the case no action is taken and the check of step  202  is performed again at periodic intervals.  
         [0038]     If the contrary is true the control goes from step  202  to step  204 . In step  204  node-B is switched to the point to multipoint multi cast mode with only one dedicated data queue per radio cell. Preferably this is done on a per cell basis such that a hybrid mode of operation of node-B can result as illustrated in  FIG. 5 .  
         [0039]     In the example shown in  FIG. 5 , there are nine user equipment UE 1 , UE 2 , . . . UE 9  within radio cell  112  which request the multimedia service. In radio cell  126  there are just three user equipment, UE 1 , UE 2 , UE 3  which request the multimedia service. As a consequence a determination is made by control module  104  in accordance with the method as illustrated in  FIG. 4  that the streaming to the user equipment within radio cell  126  is to be performed in a point to point multicast mode whereas the streaming through the user equipment within radio cell  112  is to be performed in a point to multipoint multi cast mode.  
         [0040]     Control module  108  receives a corresponding control command from control module  104  and controls node-B  106  to establish a single data queue  142  for transmitting of multimedia data stream  116  to the user equipment within radio cell  112  and to establish separate data queues  144 ,  146 ,  148  for respective user equipment in radio cell  126 , i.e. UE 1 , UE 2  and UE 3  or radio cell  126 .  
         [0041]     It is to be noted that the control module  104  can be implemented in the node-B or that the control function of control module  104  is shared by node-B and the radio network controller.  
       List of Reference Numerals  
       [0042]    
       
         
           
               100  telecommunication system  
               102  RNC  
               104  control module  
               106  node-b  
               108  control module  
               110  antenna  
               112  radio cell  
               114  server computer  
               116  multimedia data stream  
               118  lub link  
               120  data queue  
               122  data queue  
               124  data queue  
               126  radio cell  
               128  MAC-hs entity  
               130  MAC-hs entity  
               132  data queue  
               134  data queue  
               136  data queue  
               138  data queue  
               140  data queue  
               142  data queue  
               144  data queue  
               146  data queue