WO2010051851A1

WO2010051851A1 - Methods and arrangements for sending data from a multimedia broadcast multicast service node

Info

Publication number: WO2010051851A1
Application number: PCT/EP2008/065151
Authority: WO
Inventors: Hans Bertil RÖNNEKE; Jan Backman; Thorsten Lohmar
Original assignee: Telefonaktiebolaget L M Ericsson (Publ)
Priority date: 2008-11-07
Filing date: 2008-11-07
Publication date: 2010-05-14

Abstract

A method and arrangement in a multimedia broadcast multicast service node (101 ) for sending data via a gateway node (102) to a communication device (105) are provided. The gateway node (102) is configured to forward the data via at least two radio network nodes (104) to the communication device (105). The multimedia broadcast multicast service node (101) sends the data and a time stamp to the gateway node (102). The gateway node (102) is further configured to forward the time stamp to said at least two radio network nodes (104). The time stamp is used to define a point in time at which the data is to be forwarded by said at least two radio network nodes (104) to the communication device (105). Furthermore, a corresponding method and arrangement in a gateway node (102) are provided.

Description

METHODS AND ARRANGEMENTS FOR SENDING DATA FROM A MULTIMEDIA BROADCAST MULTICAST SERVICE NODE

TECHNICAL FIELD The present invention relates to a method and arrangement in a multimedia broadcast multicast service node for sending data via a gateway node to a communication device. Furthermore, the present invention relates to a method and arrangement in a gateway node for handling data from a broadcast multicast service node.

BACKGROUND

In 3GPP Long Term Evolution networks, Single Frequency Network (SFN) mode of operation may be used for broadcast transmission. In the SFN mode of operation, the participating base stations, such as enhanced Node-Bs (ΘNBS), simultaneously transmit identical Multimedia Broadcast Multicast Service (MBMS) contents via the same radio resources, or more particularly via the same Physical time/frequency Resource Blocks (PRBs). When using the SFN mode of operation, a user equipment (UE) combine transmissions from different base stations without being aware of the different sources, that is to the user equipment it appears as one transmission from one base station. It may be noted that the SFN mode of operation requires that the participating base stations are tightly synchronized. Timing requirements lay within the range of 1-5 microseconds.

Further, a user equipment in a wireless network may operate in a so called soft- combining mode. This is a user equipment, which simultaneously receives data from multiple base stations that share a common time line, and combines different copies of the received data to one set of data with an enhanced bit quality as a result. Therefore, a user equipment in a soft-combining mode can take advantage of an reduced error rate.

3GPP RAN3 have for some time been working with evolved HSPA architecture, in which, for example, the RNC is co-located with the NodeB (also referred to as NodeB÷). Thereby, a flat architecture similar to the LTE architecture is formed. In order for multimedia broadcast multicast services to work in this architecture, a new solution for synchronization of data to support soft combining and SFN-mode in NodeB+:s is required.

In "R3.022 - Enhancements for FDD HSPA Evolution", there is disclosed a method for synchronization of data for a radio communication network. The network comprises a gateway GPRS support node (GGSN)₁ a user equipment and a number of NodeB+:s. If the data sent by the multimedia broadcast multicast center (BM-SC) is received by the gateway GPRS support node at the same pace as it was sent by the multimedia broadcast multicast center, the gateway GPRS support node forwarding the user data packets is able to "timestamp" the packets in such a manner that overflow situations in NB+ can be avoided. In a step, MBMS data is sent from the gateway GPRS support node while including a time stamp in a GPRS tunnelling protocol header or other dedicated header. The time stamp is an absolute time vaiue, which is used by the NodeB+:s to determine when MBMS data shall be transmitted over the air to the user equipment. The time stamps must be set while taking into account radio access network properties, such as frame size.

A drawback of the proposed solution is that the gateway GPRS support node becomes dependent of RAN and that delay variance from a multimedia broadcast multicast service center (BM-SC) to the gateway GPRS support node is propagated down to the NodeB+:s, that is any bursts on the path from the multimedia broadcast multicast center to the gateway GPRS support node are propagated down to NodeB+:s. As a consequence, the radio interface is negatively affected. Moreover, synchronization may become inaccurate.

Another drawback of the proposed solution (in "R3.022 - Enhancements for FDD HSPA Evolution" above) is that, if MBMS is provided in a network having both UTRAN and LTE accesses, there will be unnecessary long interruptions in MBMS reception at a user equipment switching from UTRAN to LTE, or vice versa. SUMMARY

An object of the present invention is to find improved methods and arrangements for synchronizing MBMS data sent from two radio network nodes, receiving multicast addressed data, to a communication device.

According to an aspect of the invention, the object is achieved by a method in a multimedia broadcast multicast service node for sending data via a gateway node to a communication device. The gateway node is configured to forward the data via at least two radio network nodes to the communication device. The communication device is configured to receive the data from said at least two radio network nodes. The broadcast multicast service node, the communication device, the gateway node and said at least two radio network nodes are comprised in a radio communication network. In a step, the multimedia broadcast multicast service node sends the data and a time stamp to the gateway node. The gateway node is further configured to forward the time stamp to said at least two radio network nodes. The time stamp is used by said at least two radio network nodes to define a point in time at which the data is to be forwarded by said at least two radio network nodes to the communication device. In this manner, synchronization of data received by the communication device is obtained.

According to another aspect of the invention, the object is achieved by an arrangement in a multimedia broadcast multicast service node for sending data via a gateway node to a communication device. The gateway node is configured to forward the data via at least two radio network nodes to the communication device. The communication device is configured to receive the data from said at least two radio network nodes. The broadcast multicast service node, the communication device, the gateway node and said at least two radio network nodes are comprised in a radio communication network. The arrangement comprises a sending unit configured to send the data and a time stamp from the broadcast multicast service node to the gateway node. The gateway node is further configured to forward the time stamp to said at least two radio network nodes. The time stamp is usable by said at least two radio network nodes to define a point in time at which the data is to be forwarded by said at least two radio network nodes to the communication device. According to a further aspect of the invention, the object is achieved by a method in a gateway node for handling data from a broadcast multicast service node. The gateway node is configured to forward the data via at least two radio network nodes to a communication device. The communication device is configured to combine the data sent from said at least two radio network nodes. The broadcast multicast service node, the communication device, the gateway node and said at least two radio network nodes are comprised in a radio communication system. In a step, the gateway node receives the data and a time stamp from the broadcast multicast service node. The gateway node is further configured to forward the time stamp to said at least two radio network nodes. The time stamp is used by said at least two radio network nodes to define a point in time at which the data is to be sent from said at least two radio network nodes to the communication device, thereby synchronizing the data received by the communication device.

According to yet another aspect of the invention, the object is achieved by an arrangement in a gateway node for handling data from a broadcast multicast service node. The gateway node is configured to forward the data via at least two radio network nodes to a communication device. The communication device is configured to combine the data sent from said at least two radio network nodes. The broadcast multicast service node, the communication device, the gateway node and said at least two radio network nodes are comprised in a radio communication system. The arrangement comprises a receiving unit configured to receive the data and a time stamp from the broadcast multicast service node. The gateway node is further configured to forward the time stamp to said at least two radio network nodes. The time stamp is usable by said at least two radio network nodes to define a point in time at which the data is to be sent from said at least two radio network nodes to the communication device.

Since the time stamp is sent from, and set by, the broadcast multicast service node, or the broadcast multicast service center, any delay variance in a data stream, comprising data packets, from the broadcast multicast service node to the gateway node is compensated for. The time stamp ensures that data packets sent from said at least two radio network nodes are synchronized such as to allow the communication device to be operated in soft-combining and/or single frequency network mode. Advantageously, thanks to the time stamp being sent from the multimedia broadcast multicast service node, the gateway node needs not take into account what radio access network is used, i.e. the gateway node needs not to consider frame size of the radio access network. As a result, the gateway GPRS support node may be implemented in a simpler manner, with less functionality, which will invite to implement the functions of the gateway node in hardware. Thereby, fast operation of the gateway node may be provided. In this manner, improved methods and arrangements for synchronizing MBMS data sent from two radio network nodes, receiving multicast addressed data, to a communication device, have been provided.

An advantage with sending the time stamp from the broadcast multicast service node is that migration to EPS is facilitated. With the synchronization mechanism in the broadcast multicast service node, it is automatically reused for the LTE/EPS.

Moreover, if a user equipment is receiving MBMS data using UTRAN access and moves into a region where only E-UTRAN access is available, then an advantage with sending the time stamp from the broadcast multicast service node is that the gap in the transmission when changing from UTRAN to E-UTRAN access will be small, since the UTRAN and E-UTRAN radio access networks may be rather synchronized. As a result, the user equipment may continue to receive the MBMS data, while only loosing a small number of data packets.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. Those skilled in the art realize that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention, as defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS The various aspects of the invention, including its particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which: Fig. 1 shows an overview of an exemplifying wireless communication network,

Fig. 2 shows a schematic signaling chart of an exemplifying method in the wireiess communication network according to Fig. 1 ,

Fig. 3 shows a flow chart of an embodiment of the method in the multimedia broadcast multicast service node,

Fig 4 shows a schematic block diagram of an embodiment of the arrangement in the multimedia broadcast multicast service node,

Fig. 5 shows a flow chart an embodiment of the method in the gateway node,

Fig 6 shows a schematic block diagram of an embodiment of the arrangement in the gateway node,

Fig. 7 shows a schematic block diagram of an exemplifying implementation of the present solution, wherein multicast user-plane with protocol stacks including User iP, Transport !P and timing headers for synchronization are illustrated,

Fig. 8 shows an alternative schematic block diagram of an exemplifying implementation of the present solution, and

Fig. 9 shows a schematic block diagram of multicasting in an evolved HSPA network and an LTE/EPS network.

DETAILED DESCRIPTION

Throughout the following description similar reference numerals have been used to denote similar elements, parts, items or features, when applicable

Fig 1 shows an overview of an exemplifying radio communication network 100. The network 100 comprises a multimedia broadcast multicast service node, or a multimedia broadcast multicast service center, 101 , a gateway node 102, such as a gateway GPRS support node, one or more multicast enabled routers MR, 103, at least two radio network nodes 104, such as radio base stations, and a communication device 105, such as a mobile phone, a cellular phone, a mobile terminal, a PDA, a portable computer equipped with appropriate transceivers or the like.

When sending a MBMS paytoad, such as a video sequence, the multimedia broadcast multicast service node 101 sends the payioad, or the data, to the gateway node 102 while using a multicast address. Then, the gateway 102 sends the payioad to one or more multicast enabled routers 103, which in turn forwards the payioad to the radio network nodes 104 as indicated by the multicast address used. Next, the radio network nodes 104 sends the data to the communication device 105. The communication device 105 may receive the data using soft combining or single frequency network mode. For this to be feasible, a certain amount of synchronization between the data from the radio network nodes 104 is required. This synchronization is achieved by the time stamp which is sent from the multimedia broadcast multicast service node 101 in conjunction with the data to the radio network nodes 104, via the gateway node 102 and the multicast enabled routers 103.

Fig. 2 shows a schematic signaiing chart of an exemplifying method in the wireless communication network according to Fig. 1. The following steps are performed.

210 In a step 210, the multimedia broadcast multicast service node 101 sends the data, or the payioad, and the time stamp to the gateway node 102.

220 In a step 220, the gateway node 102 sends the data and the time stamp to one or more radio network nodes 104, possibly via one or more multicast enabled routers 103 (not shown).

230 Sn a step, 230, the radio network nodes 104 forward the data to the communication device 105, which receives the data using soft combining or single frequency network mode.

In embodiments of the method in the radio communication network 100, the multimedia broadcast multicast service node, or merely the broadcast multicast service node, 101 sends a plurality of data packets to the communication device 105. Even though, the multimedia broadcast multicast service node 101 may send the data packets evenly spread out in time, they may arrive at the gateway node 102 unevenly spread out in time, ! e the packets may arrive at the gateway node 102 in bursts Unless the gateway node takes into account these bursts in relation to frame size of the radio access network used, there is a risk for failure in the radio network nodes 104 when sending the data packets For example, the gateway node 102 may erroneously instruct the radio network nodes 104 to send a greater amount of data packets in one frame than actually may fit within one frame When the time stamp is set in the multimedia broadcast multicast service node 101 , variance in reception of data packets at the gateway node 102 do not affect the transmission from the radio network nodes 104 to the communication device 105, since the multimedia broadcast multicast service node 101 is configured to set the time stamps based on the radio access network used and an associated frame size As a result, the gateway node 102 is allowed to be implemented in a simple and non-complex manner, i e the gateway node 102 has only a few functions, such as forwarding and copying functions Moreover, by implementing, for example, the forwarding and copying functions in hardware, fast and reliable operation of the gateway node 102 may be achieved

Fig 3 shows a flow chart of an embodiment of the method in the multimedia broadcast multicast service node 101 for sending data via a gateway node 102 to a communication device 105 The gateway node 102 ts configured to forward the data via at least two radio network nodes 104 to the communication device 105 The communication device 105 is configured to receive the data from said at least two radio network nodes 104 The broadcast multicast service node 101 , the communication device 105, the gateway node 102 and said at least two radio network nodes 104 are comprised in a radio communication network 100 210 In a step 210, the multimedia broadcast multicast service node 101 sends the data and a time stamp to the gateway node 102 The gateway node 102 is further configured to forward the time stamp to said at least two radio network nodes 104 The time stamp is used by said at least two radio network nodes 104 to define a point in time at which the data is to be forwarded by said at least two radio network nodes 104 to the communication device 105 In thts manner, synchronization of data received by the communication device 105 is obtained

In some embodiments of the method in the multimedia broadcast multicast service node 101 , the multimedia broadcast multicast service node 101 sets the time stamp of the data, or the data packets, based on frame size of the radio access network used Advantageously, the gateway GPRS support node may be kept simple and lean, whereby operation at high speed may be allowed by, for example, hardware implemented forwarding routines

In some embodiments of the method in the multimedia broadcast multicast service node 101 , the broadcast multicast service node 101 uses multicast addressing on user level to send data to the gateway node 102 The user level is the content packets (or data packets) sent from broadcast multicast service node and ultimately received by a user equipment, in which the IP stack is enabled to receive packets on selected !P multicast addresses

In some embodiments of the method in the multimedia broadcast multicast service node 101 , the time stamp is sent in a separate header between the broadcast multicast service node 101 and the gateway node 102

In some embodiments of the method in the multimedia broadcast multicast service node 101 , the radio network node is a radio base station, such as a 3GPP Radio Network Controller, a 3GPP NodeB, a 3GPP NodeB comprising an Radio Network Controller, a 3GPP eNodeB or the like

Fig 4 shows a schematic block diagram of an embodiment of the arrangement 500 in the multimedia broadcast multicast service node 101 for sending data via a gateway node 102 to a communication device 105 The gateway node 102 is configured to forward the data via at least two radio network nodes 104 to the communication device 105 The communication device 105 is configured to receive the data from said at least two radio network nodes 104 The broadcast multicast service node 101 , the communication device 105, the gateway node 102 and said at least two radio network nodes 104 are comprised in a radio communication network 100 The arrangement 500 may, optionally, comprise a receiving unit 510 and a processing unit 520 The arrangement 500 comprises a sending unit 530 configured to send the data and a time stamp from the broadcast multicast service node 101 to the gateway node 102 The gateway node 102 is further configured to forward the time stamp to said at least two radio network nodes 104 The time stamp is usable by said at least two radio network nodes 104 to define a point in time at which the data is to be forwarded by said at least two radio network nodes 104 to the communication device 105.

In some embodiments of the arrangement 500, the broadcast multicast service node 101 uses multicast addressing on user level to send data to the gateway node 102.

In some embodiments of the arrangement 500, the time stamp is sent in a separate header between the broadcast multicast service node 101 and the gateway node 102.

In some embodiments of the arrangement 500, the radio network node is a radio base station, such as a 3GPP Radio Network Controlier, a 3GPP NodeB, a 3GPP NodeB comprising an Radio Network Controller, a 3GPP eNodeB or the like.

Fig. 5 shows a flow chart an embodiment of the method in the gateway node 102 for handling data sent from a broadcast multicast service node 101. The gateway node 102 is configured to forward the data via at least two radio network nodes 104 to a communication device 105. The communication device 105 is configured to combine the data sent from said at least two radio network nodes 104. The broadcast multicast service node 101 , the communication device 105, the gateway node 102 and said at least two radio network nodes 104 are comprised in a radio communication system 100. 210 in a step 210, the gateway node receives the data and a time stamp from the broadcast multicast service node 101. The gateway node 102 is further configured to forward the time stamp to said at least two radio network nodes 104. The time stamp is used by said at least two radio network nodes 104 to define a point in time at which the data is to be sent from said at least two radio network nodes 104 to the communication device 105, thereby synchronizing the data received by the communication device 105.

In some embodiments of the method in the gateway node 102, the time stamp is sent in a separate header between the broadcast multicast service node 101 and the gateway node 102.

In some embodiments of the method in the gateway node 102, the gateway node 102 uses IP multicast addressing for forwarding of the data to said at least two radio network nodes 104. IP Multicast (as specified in, for example, IETF RFCs 3171 , 3376, 3810, 4601 , 4604, 4607) is when a sender sends a single datagram (from the sender's unicast address) to the multicast address and intermediate routers MR forward the datagram on al! its ports (interfaces) where there are receivers that have registered to receive data to that specific multicast group.

In some embodiments of the method in the gateway node 102, support for the time stamp is implemented in a GPRS tunneling protocol header, GTP header, used for sending of data between the gateway node 102 and said at least two radio network nodes 104.

in some embodiments of the method in the gateway node 102, the gateway node 102 is a gateway GPRS support node, GGSN, for 3GPP 3G & 2G networks.

In some embodiments of the method in the gateway node 102, the gateway node 102 is a Packet Data Node, PDN gateway, for LTE networks.

Fig. 6 shows a schematic block diagram of an embodiment of the arrangement 600 in the gateway node 102 for handling data from a broadcast multicast service node 101. The gateway node 102 is configured to forward the data via at least two radio network nodes 104 to a communication device 105. The communication device 105 is configured to combine the data sent from said at least two radio network nodes 104. The broadcast multicast service node 101 , the communication device 105, the gateway node 102 and said at least two radio network nodes 104 are comprised in a radio communication system 100. The arrangement 600 comprises a receiving unit 610 configured to receive the data and a time stamp from the broadcast multicast service node 101. The gateway node 102 is further configured to forward the time stamp to said at least two radio network nodes 104. The time stamp is usable by said at least two radio network nodes 104 to define a point in time at which the data is to be sent from said at least two radio network nodes 104 to the communication device 105. Optionally, the arrangement 600 further comprises a processing unit 620 and a sending unit 630.

In some embodiments of the arrangement 600 in the gateway node 102, the time stamp is sent in a separate header between the broadcast multicast service node 101 and the gateway node 102. In some embodiments of the arrangement 600 in the gateway node 102, the gateway node 102 uses IP multicast addressing for forwarding of the data to said at least two radio network nodes 104.

In some embodiments of the arrangement 600 in the gateway node 102, support for the time stamp is implemented in a GPRS tunneling protocol header, GTP header, used for sending of data between the gateway node 102 and said at least two radio network nodes 104.

In some embodiments of the arrangement 600 in the gateway node 102, the gateway node 102 is a gateway GPRS support node, GGSN, for 3GPP 3G & 2G networks.

In some embodiments of the arrangement 600 in the gateway node 102, the gateway node 102 is a Packet Data Node, PDN gateway, for LTE networks.

Fig. 7 shows a schematic block diagram of an exemplifying implementation of the present solution, wherein multicast user-plane with protocol stacks including User IP, Transport SP and timing headers for synchronization are illustrated.

The system, in the upper portion of Fig. 7, comprises a user equipment, UE, a NodeB, a radio network controller, RNC, a serving GPRS support node, SGSN, a gateway GPRS support node, GGSN and a multimedia broadcast multicast service center (or multimedia broadcast multicast service node). The NodeB and the radio network controller may be combined to form a NodeB+ using 3GPP terminology. As a consequence, the NodeB÷ comprises the NodeB and the radio network controller. The bold arrow from the gateway GPRS support node to the radio network controller indicates transmission using multicast addressing, in Fig. 7, the transmission using multicast addressing, as indicated by the bold arrow, is termed transport IP multicast (T-IP). This same transmission is also indicated by the dashed arrow, in the lower portion of Fig. 7, from the T-IP layer in the MC Source (i.e. the GGSN), forwarded by a multicast enabled router (MC), to the T-IP layer in the MC receiver (i.e. RNC or NodeB÷). The dashed arrows in the upper portion of Fig 7 between the "U-IP' entities, indicate an example of a protocol with an IP multicast carrying the MBMS data from the BM-SC to the UE over the gateway GPRS support node and the NodeB÷

In the mid portion of Fig 7, the dashed arrow between the BM-SC and the RNC

(NodeB+) the timing header for synchronization (T) is indicated The timing header for synchronization is sent by the BM-SC, forwarded by the GGSN₁ and any intermediate muiticast enabled routers, MR, and received by the RNC (or NodeB+) The GPRS tunnelling protocol header, GTP, may optionally be used between the GGSN and the RNC as indicated in Fig 7 or it may be omitted as indicated in Fig 8 (see below) A layer IP-1 illustrates a layer for tunnelling of data from the BM-SC to the GGSN The gateway GRPS support node has the function of being a muiticast source, MC source, and the radio network controller, or NodeB÷, has the function of being a multicast receiver, MC receiver The timing header for synchronization, T, may comprise, in addition to the time stamp, one or more counters for counting of bytes, data packets and the like for the purpose of maintaining the synchronization Layer L1 is the physical communication layer, which may be different for different Sinks e g optical layers, WCDMA Physical Layer, etc Layer L2 is the link communication layer, which may be different for different links e g Ethernet, Medium Access Control (MAC), Radio Link Control (RLC) etc

Consider the following scenario The MBMS payload, including the user IP header with a multicast address corresponding to the service (temporary mobile group identity allocated to the MBMS service), is passed transparently from the multimedia broadcast multicast service center to the user equipment if the UE has joined the particular multicast group, its IP stack will accept the packets and deliver them to the application The timing info, i e the time stamp, is added by the BM-SC to the MBMS payload before it is passed to the IP stack It is passed transparently to the radio network controller, which removes it and uses it for its synchronization in the combined radio network controlier and NodeB, i e a NodeB+ The format of the timing header for synchronization may be any format suitable for the RAN, since it has no core network impact When the gateway GPRS support node receives a Diameter Session Start message from the multimedia broadcast multicast service center, it allocates a new Transport IP Multicast address to use for the new session The Transport IP Multicast address is added to the GTP-C Session Start message and when received by the radio network controller, the radio network controller joins the specified Transport IP Multicast group. When the gateway GPRS support node starts to receive MBMS payload packets (from the multimedia broadcast multicast service center), it forwards the packets using the Transport IP Multicast address it has allocated.

A GTP/UDP (user datagram protocol) header may optionally be used for MBMS payload by the gateway GPRS support node in the core network The GTP header is designed as a unicast transport protocol and an advantage to use it for multicast transport may be that the RNC (NodeB+) does already have a GTP stack for unicast reception It may be sufficient to only use UDP, e.g. if a need to distinguish sub-flows within the session would arise (e.g. multiple quality of service). The MBMS payload is forwarded by multicast enabled routers, MR, directiy from the gateway GPRS support node to radio network controllers (NodeB+s). That is, the serving GPRS support node is not invoived in the MBMS user plane,

Sn Fig. 8, there is illustrated an alternative embodiment of the present solution, in which the GTP header is omitted. Similar or same elements are denoted by the same reference numeral as in Fig. 7.

Fig. 9 shows a schematic block diagram of multicasting in an evolved HSPA network and an E-UTRAN/EPS network. In the Figure, a muiti-cell/mυlticast coordination entity MCE is used for synchronizing in SFN mode, a first multimedia broadcast multicast service node MBMS1 is used for control and signaling of MBMS bearers in the EPS network and a second multimedia broadcast multicast service node MBMS2 is used as gateway towards evolved BM-SC. For further details, refer to 3GPP TS 23.246 V8 2.0 The present solution takes migration to EPS into account when selecting the architecture for MBMS enhancements for Evolved HSPA By placing the time-stamping for synchronization in the BM-SC, rather than in the GGSN, which otherwise may be a natural choice since the multicasting begin in the GGSN, migration to EPS may be simplified For example, the interruption when a UE is moving between UTRAN and E- UTRAN may be minimized. Also, since the BM-SC is a node in Gn-core and EPS networks and its function remain rather unchanged when MBMS is evolved to EPS In Fig. 9, there is demonstrated how the proposed evolved HSPA solution matches the architecture of EPS as of current status of agreed entities. From Fig. 9, it may be seen that one solution may during certain circumstances serve al! 3GPP accesses.

Even though the invention has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art. The described embodiments are therefore not intended to limit the scope of the invention, which is defined by the appended claims.

Claims

1. A method in a broadcast multicast service node (101 ) for sending data via a gateway node (102) to a communication device (105), wherein the gateway node (102) is configured to forward the data via at least two radio network nodes (104) to the communication device (105), wherein the communication device (105) is configured to receive the data from said at least two radio network nodes (104), wherein the broadcast multicast service node (101 ), the communication device (105), the gateway node (102) and said at least two radio network nodes (104) are comprised in a radio communication network (100), the method comprising sending (210) the data and a time stamp from the broadcast multicast service node (101 ) to the gateway node (102), wherein the gateway node (102) further is configured to forward the time stamp to said at least two radio network nodes (104), wherein the time stamp is used by said at least two radio network nodes (104) to define a point in time at which the data is to be forwarded by said at least two radio network nodes (104) to the communication device (105), thereby synchronizing data received by the communication device (105).

2. The method according to claim 1 , wherein the broadcast multicast service node (101 ) uses multicast addressing on user level to send data to the gateway node (102).

3. The method according to any one of the preceding claims, wherein the time stamp is sent in a separate header between the broadcast multicast service node (101) and the gateway node (102).

4. The method according to claim 1 , wherein the radio network node is a radio base station, such as a 3GPP Radio Network Controller, a 3GPP NodeB, a 3GPP NodeB comprising an Radio Network Controller, a 3GPP eNodeB or the like.

5. An arrangement (500) in a broadcast multicast service node (101 ) for sending data via a gateway node (102) to a communication device (105), wherein the gateway node (102) is configured to forward the data via at least two radio network nodes (104) to the communication device (105), wherein the communication device (105) is configured to receive the data from said at least two radio network nodes (104), wherein the broadcast multicast service node (101), the communication device (105), the gateway node (102) and said at ieast two radio network nodes (104) are comprised in a radio communication network (100), the arrangement (500) comprising a sending unit (530) configured to send the data and a time stamp from the broadcast multicast service node (101 ) to the gateway node (102), wherein the gateway node (102) further is configured to forward the time stamp to said at least two radio network nodes (104), wherein the time stamp is usable by said at least two radio network nodes (104) to define a point in time at which the data is to be forwarded by said at least two radio network nodes (104) to the communication device (105).

6. A method in a gateway node (102) for handling data from a broadcast multicast service node (101 ), wherein the gateway node (102) is configured to forward the data via at ieast two radio network nodes (104) to a communication device (105), wherein the communication device (105) is configured to combine the data sent from said at least two radio network nodes (104), wherein the broadcast multicast service node (101 ), the communication device (105), the gateway node (102) and said at ieast two radio network nodes (104) are comprised in a radio communication system

(100), the method comprising receiving (210) the data and a time stamp from the broadcast muiticast service node (101), wherein the gateway node (102) further is configured to forward the time stamp to said at least two radio network nodes (104), wherein the time stamp is used by said at least two radio network nodes (104) to define a point in time at which the data is to be sent from said at ieast two radio network nodes (104) to the communication device (105), thereby synchronizing the data received by the communication device (105).

7. The method according to claim 6, wherein the time stamp is sent in a separate header between the broadcast multicast service node (101) and the gateway node (102).

8. The method according to claim 6 or 7, wherein the gateway node (102) uses IP multicast addressing for forwarding of the data to said at least two radio network nodes (104).

9. The method according to any one of claims 6-8, wherein support for the time stamp is implemented in a GPRS tunneling protocol header, GTP header, used for sending of data between the gateway node (102) and said at least two radio network nodes (104).

10. The method according to any one of claims 6-9, wherein the gateway node (102) is a gateway GPRS support node, GGSN, for 3GPP 3G & 2G networks.

11. The method according to any one of claims 6-10, wherein the gateway node (102) is a Packet Data Node, PDN gateway, for LTE networks.

12. An arrangement (600) in a gateway node (102) for handling data from a broadcast multicast service node (101 ), wherein the gateway node (102) is configured to forward the data via at least two radio network nodes (104) to a communication device (105), wherein the communication device (105) is configured to combine the data sent from said at least two radio network nodes (104), wherein the broadcast multicast service node (101), the communication device (105), the gateway node (102) and said at least two radio network nodes (104) are comprised in a radio communication system (100), the arrangement (600) comprising a receiving unit (610) configured to receive the data and a time stamp from the broadcast multicast service node (101), wherein the gateway node (102) further is configured to forward the time stamp to said at least two radio network nodes (104), wherein the time stamp is usable by said at least two radio network nodes (104) to define a point in time at which the data is to be sent from said at least two radio network nodes (104) to the communication device (105).