GB2427982A - Determining whether broadcast/multicast content is to be delivered by a further network - Google Patents

Abstract

A method of determining in a first network whether broadcast/multicast content is to be transmitted by a further network to a plurality of mobile communication devices able to receive the broadcast/multicast content from the first or further networks comprises receiving information associated with a radio access network of the first network; making a determination based on the received information at a radio network controller in the first network whether broadcast/multicast content should be transmitted by the further network; and, upon a positive determination; redirecting the broadcast/multicast content from the first network to an intermediate device in communication with the further network; and transmitting, from the further network, the broadcast/multicast content to at least one mobile communication device.

Description

IMPROVEMENTS IN CELLULAR CONTENT DISTRIBUTION

The present invention relates to improvements in cellular content distribution, and in particular to a method and apparatus that redistributes cellular content via a separate broadcast network.

The term broadcast/multicast content is intended to encompass any common content that can be transmitted in a broadcast or multicast mode.

This does not include unicast content.

In known cellular telecommunication systems, when services are broadcast or multicast to a number of registered users of the service over a cellular network, problems may occur due to the cellular network only targeting a small area relative to broadcast networks. Example broadcast networks are Digital Video Broadcast (DVB), Digital Audio Broadcasting (DAB) and Digital Multimedia Broadcasting (DMB). The targeting of such a small area results in a high granularity in the distribution of broadcast information.

A basic structure of a Universal Mobile Telecommunications System (UMTS) network is shown in Figure 1A. UMTS concerns a 3G (3' Generation) radio network that uses wideband code division multiple access (W-CDMA) technology. A core network 101 is connected to a UMTS Terrestrial Radio Access Network (UTRAN) 103 via an lu interface. The UTRAN 103 is connected to User Equipment (UE) 105 via a radio interface Uu. The UEs are mobile communication devices, for example, mobile telephones, personal digital assistants (PDAs), or the like.

A more detailed view of UTRAN architecture is shown in Figure lB.

UTRAN 103 is made up of a number of Radio Network Subsystems (RNS) 111. The RNS is connected to the core network 101 via the lu interface 109, as described above. The core network includes a Serving GPRS Support Node (SGSN) 108 and a Gateway GPRS Support Node (GGSN) 107.

Within each RNS 111 is a Radio Network Controller (RNC) 113 and a number of base stations 115 used as transmitters. In the case of UTRAN, the base station is called a Node B. Each base station 115 connects to the RNC 113 via an lub interface 114. Each RNC 113 may be interconnected to one or more other RNCs 113 using an iui interface 112.

Multicast or broadcast content is forwarded from a radio network controller (RNC) 113 via the Tub interface to a number of base stations 115.

The base stations 115 transmit the content to any number of mobile communication devices (or User Equipment (UE)) located within the base stations transmission area.

This system results in the same content being distributed over a number of different interfaces and channels. That is, identical broadcast/multicast content is distributed over any number of lu interfaces, lub interfaces and physical layer (PHY) channels resulting in a waste of the network's capacity. This is not efficient use of the system architecture and resources.

Another problem that can occur is in the form of interference due to the increased transmission power and number of PHY channels required to transmit the large amount of content through the system and specifically over the air interface.

Further problems can occur when the network becomes too busy resulting in a slower transfer of content to users. In addition to this, users may require higher bit-rates, increased power or increased bandwidth for certain broadcast/multicast content, which the current network is unable to support adequately. Also, the network may not be able to support the Quality of Service (QoS) required for the delivery of the broadcast/multicast content.

Further, in the case of emergency use, a sufficient number of channels may not be easily available at the required time in order to support the emergency services. It may be preferable at certain times to transmit critical applications over the broadcast network rather than the cellular network.

On the other hand, in known broadcast networks a number of problems may occur due to the broadcast network targeting a large area relative to the above-described cellular network. This targeting results in a low granularity of broadcast/multicast content. That is, a broadcast access point (BC AP) transmits one type of content over a large area for all users to access.

It has been proposed that a new logical entity decides through which network, for example, 3G or WLAN, to send broadcast content. In this proposal, it is discussed that the level of integration between the two networks may vary.

For example, the 3G and WLAN networks may be attached at the RNC level, wherein the WLAN network may be considered as a cell that is controlled by the SGSN of the 3G network. This requires a considerable amount of network integration, resulting in a high cost solution and an increased signalling overhead.

Alternatively, the networks may be integrated at a higher level, such that they are attached at the core network (e.g. the GGSN). In this example, there is minimal integration between the two networks. As the decision is being taken deep within the core network, there is a significant lack of dynamic selectivity.

The present invention aims to overcome or at least alleviate some or all of the aforementioned problems.

In one aspect, the present invention provides a method of determining in a first network whether broadcast/multicast content is to be transmitted by a further network to a plurality of mobile communication devices, said devices being operable to receive the broadcast/multicast content from the first or further networks, the method comprising the steps of: receiving information associated with a radio access network of the first network; making a determination based on the received information at a radio network controller in the first network whether broadcast/multicast content should be transmitted by the further network; and, upon a positive determination; redirecting the broadcast/multicast content from the first network to an intermediate device in communication with the further network; and transmitting, from the further network, the broadcast/multicast content to at least one mobile communication device.

The present invention provides the advantage of dynamically determining within a radio network controller of a first network whether one of a number of further networks should be used for the transmission of broadcast/multicast content based on fed back radio access network information. This is because, in a core network based decision system, the RAN-based information has to be signalled all the way back to the core network (for example, to the GGSN), whereas in this invention, the decision is made at the RNC, thus providing a switching process that is faster than if the decision were being taken within the core network of the first network.

In one aspect of the invention, information concerning the number of lub or lu connections required to transmit the broadcast/multicast content is fed back to the RNC, either from the base stations (Tub) or from the SGSN (lu). The broadcast/multicast content is then transmitted from a base station in a first network to a relay, which converts the content for transmission over a second network. Therefore, a dynamic determination is made as to which network should be used to transmit the content. Further, the content only passes through the second networks radio access network without the requirement for it to pass through its core network.

In a further aspect of the invention, the determination as to which network should transmit the broadcast/multicast content is made by determining the distribution characteristics of the UEs with respect to the transmission footprints of the different networks.

Specific embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure IA shows a block diagram of a known cellular network system; Figure lB shows a more detailed block diagram of a known cellular network system; Figure 2 shows a system block diagram of networks according to a first embodiment of the present invention; Figure 3 shows a cell layout indicating a first UE distribution; Figure 4 shows a cell layout indicating a second UE distribution; Figure 5 shows a cell layout indicating a third UE distribution;

FIRST EMBODIMENT

Figure 2 shows a network with a GGSN 201 connected to a SGSN 203.

The SGSN 203 is connected on one lu interface 109 to a standard cellular network comprising a RNC 113, base stations 115 connected to the RNC 113 via lub interfaces 114. A group of UEs 105 are connected to the base stations 115 over air interfaces (Uu) 116. UEs within these groups 105 can receive the broadcast/multicast content from their respective base stations 115.

The SGSN 203 is connected via a second lu interface 205 to a second RNC 207. This RNC 207 is connected to several base stations (21 1A, 21 lB and 211C) via lub interfaces 209. Uu interfaces 212 connect the base stations 211 to a group of UEs 213. In cellular mode, the UEs within the group 213 can receive broadcast/multicast content from their respective base stations (211 A, B or C) In this embodiment, the RNC 207 makes a determination as to whether broadcast/multicast content can continue to be efficiently distributed over the current cellular network. The RNC 207 makes the determination based on information associated with the RAN. In this embodiment, the information is associated with the number of lub interface connections being used to send broadcast/multicast content to UEs registered to receive the content. If the number of lub connections exceeds a pre-determined threshold, the RNC 207 makes a decision to redirect the broadcastlmulticast content for transmission using a different network other than the current cellular network. The predetermined threshold may be operator defined or implementation based.

In this embodiment, the alternative network is a DVB network.

As an alternative, information on the number of lu interface connections 205 could be used by the RNC to determine which network should be used. In this alternative, the SGSN is capable of counting the number of lu interface connections. The SGSN signals the number to the RNC in order for the RNC to redirect the broadcast/multicast content.

As a further alternative, it will be understood that other parameters may be used in the determination process, as described in the further embodiments below.

If the RNC 207 makes a determination that it is more beneficial for the DVB network to transmit the broadcastlmulticast content, it redirects the broadcast/multicast content over lub interface connection 209 to the base station that is situated nearest to the DVB network's transmitter 217, in this example, base station 211C. The base station nearest to the DVB network transmitter is found through an internal process within the RNC, optionally utilising information within a database store. The RNC is adapted to determine which base station (211 A, B or C) is closest to the DVB network transmitter by using a location mapping process. Location mapping is possible, as the RNC has information concerning the location of the base stations and the DVB network transmitter. As an alternative, this information may be obtained from a database store.

The DVB network transmitter is a broadcast/multicast content access point (BC AP) 217. The BC AP 217 has incorporated therein an intermediate device, which, in this embodiment, is a relay 215. Alternatively, the relay may be located near to, but still be in communication with, the BC AP 217.

The BC AP 217 has a broadcast coverage area 219 (transmission footprint) that encompasses the UEs 213 normally serviced by the cellular network.

The nearest base station (in this example, 211C) transmits the broadcast!multicast content in its cellular format. The relay 215 receives the broadcast/multjcast content in a cellular format and converts the broadcast/multicast content into a form suitable for transmission by the BC AP 217 over the DVB network. The relay includes functionalities and signalling protocol mechanisms therein to support the conversion of the content into the alternative network. For example, to allow the content to be mapped onto the physical and logical channels of the alternative network Meanwhile, the RNC 207 forwards signalling control messages to the UEs 213 over the lub and Uu interfaces (209, 212) of the cellular network instructing the UEs to switch from a first cellular network broadcast/multicast content reception mode to an alternative network DVB broadcast/multicast content reception mode.

The DVB BC AP 217 transmits the broadcast/multicast content in a DVB format using its air interface 218 to reach the broadcast coverage area 219. The UEs 213 are adapted to receive the broadcastlmulticast content via the alternative DVB network transmitter.

In this embodiment, the UEs 213 are still connected to the first cellular network using associated signalling over the Uu interface 212 in order to ensure they are synchronised with the cellular network. The cellular network can then send associated signalling to the UE to switch back to a cellular broadcast/multicast content reception mode. In this scenario, the TilE has two receivers.

Alternatively, the connections to the first cellular network can be scheduled at certain time intervals to minimise the signalling required. In this manner, the cellular network can stay in communication periodically with the UEs 213.

As a further alternative, associated signalling from the cellular network can be transmitted via the relay and BC AP using the DVB network.

In a further alternative, the UE is not required to monitor the cellular network. Instead, the UE is adapted to switch over to receive the broadcastlmulticast content from the DVB network until a timer within the UE expires, at which point the UE switches back to receiving the broadcast/multicast content from the cellular network. In this scenario, the UE only requires one receiver.

Various combinations of the above mentioned alternatives might also be implemented.

SECOND EMBODIMENT

The same components are used in this embodiment as those described in the first embodiment. In particular, the elements making up the system as shown in Figure 2 are incorporated in this embodiment.

However, in this second embodiment, the determination by the RNC as to whether the transmission of broadcast/multicast content is carried out by the first cellular network or the alternative DVB network is made based upon determining the distribution of the UEs using the current cellular network with reference to the target transmission coverage area, and whether it is more efficient to broadcast/multicast content to the UEs via the cellular network or the alternative DVB network.

Alternatively, it will be understood that other parameters may be used in the determination process, as described in the further embodiments below.

In order for this decision to be made, geographical mapping of the UEs is carried out to compare the distribution of the UEs in relation to the base station cells with the distribution of the UEs in relation to the broadcast coverage area of the DVB network. The cellular network implements this by recording the known position of each UE. The coordinate position of each UE is known because the RNC knows which base station is in communication with the UE, and so can pin point the position of the UE down to a few tens of meters.

Also, the transmission coverage area of the DVB system would be known from data available from the DVB providers. By inserting the co- ordinates of the transmission footprint into the geographical mapping system, the system is able to deduce which cells have transmission footprints covering certain UEs, and whether those UEs are within the transmission footprint of the DVB broadcast network.

It is only possible to determine the location of a UE that is currently in a dedicated mode, rather than in an idle mode. If sufficient UEs are in a dedicated mode, then it is not necessary to determine how many UEs are at a certain location in idle mode in order to make a sensible determination of the UE distribution. However, if there are not a sufficient number of UEs in a dedicated mode to make a sensible determination about the distribution, the system can force some, or all, of the UEs within the cell to carry out a Cell- Update process enabling the RNC to determine their location and hence their distribution.

Figure 3 shows a cell layout indicating a first example UE distribution. It can be seen that cell broadcast areas 301 are depicted to indicate the transmission coverage of the base stations in the cellular network.

The UEs 303 are scattered around an area covering a number of different broadcast cells. In this example, the UEs are spread over the transmission footprint of seven base stations.

A DVB transmission footprint 305 is also depicted. It can be seen that the DVB transmission footprint 305 provides coverage to all of the UEs.

Therefore, in this scenario, it would be more efficient to transmit the broadcast/multicast content over the single DVB network rather than using seven base stations to transmit content over the cellular network.

Figure 4 shows a second example UE 403 distribution. The UEs 403 in this scenario fall within the coverage of only three cells 401 in the cellular network. So, although the DVB transmission footprint 405 includes all the UEs 403, it would be more efficient to use just the three base stations providing the cellular coverage to transmit the broadcast/multicast content to the UEs 403. Using the DVB system to transmit the content to the liEs would not be an efficient use of the DVB network bandwidth, Figure 5 shows a third example of UE 503 distribution. As can be seen form Figure 5, the UEs 503 are distributed into two main groups. The DVB transmission footprint 505 covers one group, whereas another group is outside of the DVB transmission footprint 505, but is included within one cellular base station transmission footprint 501. In this situation, it would be more efficient to use the DVB system to transmit the content to the UEs 503 within the transmission footprint area 505, and simultaneously use a single base station to cover the cellular area 501 in which the remaining UEs are located.

FURTHER EMBODIMENTS

it will be understood that embodiments of the present invention are described herein by way of example only, and that various changes and modifications may be made without departing from the scope of the invention.

It will be understood that other parameters may be used by the RNC in the determination process other than counting the number of lub or lu interface connections.

The determination may be based upon the type of broadcast/multicast content to be transmitted.

A first example of the detennination being based on the type of broadcastlmulticast content to be transmitted is having the importance of the content to be received by the UEs influencing the determination process. That is, if it is important that content is required to get through to the UEs quickly, using an alternative network that is not being used at its full capacity would be beneficial. Also, it may be necessary to warn certain groups of people located in one area about a localised event that affects the population in that area. For example, in an emergency situation, it may be more efficient to transmit emergency information over a DVB network area to specifically target that localised area, rather than transmitting the emergency information using a large number of base stations.

A further example of the broadcastlmulticast content type influencing the determination process is the bit-rate or bandwidth requirement for the content. That is, it may be a requirement that content is to be transmitted at a specific bit rate or bandwidth, high or low. An alternative network may be more suitable for transmission than the current network.

Also, the determination may be based upon the characteristics of the transmission channel within the current or alternative network.

For example, the transmission channel of a first network may be subject to some unwanted interference, for example, due to localised conditions. Therefore, it may be more efficient to use an alternative network.

In a further example, the Quality of Service (Q0S) of the provided service in the first network may influence the determination process as it may not be suited to the broadcastlmulticast content being transmitted, and so switching to an alternative network may provide the required Q0S.

Also, the determination may also be based upon the capabilities of the transmitter being used in the current or alternative network.

For example, the area coverage of the transmitter in the current network may influence the determination process, as it may not allow a large proportion of users to receive the broadcast/multicast content. Whereas, an alternative network's transmitter may be better suited for transmitting the broadcast/multicast content to all the users. Alternatively, using a different network's transmitter may provide more efficient coverage of a specified area in which users wishing to receive the broadcast/multicast content are located, and so the alternative network should be used.

A further example is the capacity at the RAN level of the current system influencing the determination process. That is, if the current network is close to reaching its maximum capacity for supporting the current broadcast, an alternative network, with more free capacity could be used to ease the load of the current network.

Further, switching to the further network could be implemented only when the RNC of the first network knows that there is available capacity for the alternative network to support the broadcast of the information through that alternative network. That is, the RNC stores information on the available capacity of the alternative network, and only allows switching to the alternative network when the alternative network is able to support the broadcast.

It will also be understood that the determination as to whether to switch to an alternative network may be made using a combination of information concerning the location and number of lu and lub connections, and the power requirements needed to transmit the content to the UEs. For example, if the UEs are far away from the base stations then high power is required to distribute the broadcast/multicast content over the cellular network. Whereas, using an alternative network, such as a DVB network, power may be saved. Of course, if the UEs are close to the base stations in the cellular network, then power may be saved by using the cellular network.

In a further example, if, due to the distribution of UEs, two node Bs being used to transmit data to the UEs are controlled by two different RNCs, then it may be more beneficial to use an alternative network. Whereas, if the two node Bs were under the control of only one RNC, it may be more beneficial for the cellular network to continue broadcasting the content. Any combination of these parameters may be utilised in order to make a determination as to which network is to be used to broadcast the content.

It will be understood that, as an alternative to the intermediate device being a relay, a specifically adapted UE may be used to act as a relay and convert the broadcastlmulticast content from one network format to another network format prior to forwarding the content to an alternative network transmitter. In this manner, any specifically adapted TIE that is in close proximity to an alternative network's transmitter may be utilised for this purpose.

For the avoidance of doubt, protection is hereby sought for any and all of the novel embodiments described above, singly and in combinations.

Claims (26)

1. A method of determining in a first network whether broadcast/multicast content is to be transmitted by a further network to a plurality of mobile communication devices, said devices being operable to receive the broadcast/multjcast content from the first or further networks, the method comprising the steps of: receiving information at a radio access network of the first network; making a determination at a radio network controller in the first network whether broadcast/multicast content should be transmitted by the further network, said determination being made based on the received information; and, upon a positive determination; redirecting the broadcastlmulticast content from the first network to an intermediate device in communication with the further network; and transmitting, from the further network, the broadcast/multicast content to at least one mobile communication device.

2. The method of claim 1, wherein within the further network, the broadcastlmulticast content only passes through a radio access network.

3. The method of claim 1, wherein the information received is associated with the distribution of mobile communication devices within a target transmission coverage area and the determination is made based on a comparison of the distribution of the mobile communication devices with the transmission coverage areas of the first and further networks.

4. The method of claim 3, wherein the power required to transmit the broadcast/multicast content is also taken into account when making the determination.

5. The method of claim I, wherein the information received is associated with the number of lub or lu interface connections.

6. The method of claim 1 wherein the content is transferred from the first network to the further network using a method comprising the further steps of: redirecting the broadcastlmulticast content to a selected transmitter in the first network, via the core network and radio network controller of the first network; transmitting the broadcast/multicast content from the transmitter in the first network to the intermediate device; transferring the broadcast/multicast content from the intermediate device to a transmitter in the further network.

7. The method of claim 6 further comprising the step of the intermediate device converting the broadcast/multicast content to a suitable format for transmission over the further network's air interface.

8. The method of claim 6, wherein the selection of the transmitter in the first network is made based on its location when compared to the location of the further network's transmitter.

9. The method of claim 1, wherein the intermediate device is a relay.

10. The method of claim 1, wherein the intermediate device is a mobile communication device adapted to act as a relay.

11. The method of claim 1, wherein the determination is made based on information associated with the type of broadcast/multicast content to be transmitted.

12. The method of claim 11, wherein the determination is made based on information associated with the importance, bit-rate or bandwidth of the broadcastlmultjcast content.

13. The method of claim 1, wherein the determination is made based on information associated with the characteristics of the transmission channel in the first or further networks over which the broadcast/multicast content is to be transmitted.

14. The method of claim 13, wherein the characteristics of the transmission channel are one of level of interference or Quality of Service.

The method of claim 2, wherein the determination is based on information associated with the capabilities of the transmitter in the first or further networks adapted to transmit the broadcast/multicast content.

16 The method of claim 15 wherein the properties are one of area coverage or capacity.

17 The method of claim 1, further comprising the step of: transmitting signalling to the mobile communication device instructing the mobile communication device to switch from reception of broadcastlmultjcast content from the further network back to the first network.

18 The method of claim 17 wherein the signalling is transmitted from a transmitter of the first network.

19 The method of claim 17 wherein the signalling is transmitted from the further network with the broadcast/multicast content.

20. The method of claim 1, wherein the mobile communication device switches reception of broadcast/multicast content from the further network back to the first network after a preset time.

21. The method of claim 1, wherein the first network is a cellular telecommunications network.

22. The method of claim 1, wherein the further network is a digital broadcast network.

23. A cellular telecommunications network adapted to perform the method of claim 17.

24. A digital broadcast network adapted to perform the method of claim 18.

25. A relay adapted to perform the method of claim 9.

26. A mobile communication device adapted to perform the method of claim 10.