HK1105725B - Optimised iub transport - Google Patents

Description

Optimized IUB transport

Technical Field

The present invention relates to optimized transmission of one media stream in a plurality of cells served by the same base station equipment, the media stream being transmitted from a radio network controller to the base station equipment via an Iub interface and comprising multimedia data, e.g. within MBMS (multimedia broadcast/multimedia service) of 3GPP (third generation partnership project).

Background

The 3GPP standard relates to a technology based on a radio access network such as UTRAN (universal mobile telecommunications (UMTS) terrestrial radio access network), which is a radio access network architecture providing W-CDMA (wideband code division multiple access) to mobile terminals. The telecommunication system according to the 3GPP standard provides higher transmission bit rates, high service flexibility and multiple simultaneous connections to mobile terminals and is able to offer new service types to users. The MBMS included in the 3GPP standard provides users with broadcast/multicast of various multimedia information, thereby enabling information providers to simultaneously transmit multimedia information such as real-time audio and video, still images and text, e.g., news, sports results and weather reports, to several users joining the MBMS.

In a telecommunication system according to the 3GPP standard, a UE, i.e. a mobile terminal such as a cellular phone with a SIM (subscriber identity module) card, communicates with a core network connected to external networks, e.g. the internet and the PSTN (public switched telephone network), via a UTRAN covering a geographical area divided into cells with unique identities. Each cell is served by a base station equipment, which in 3GPP is called a node B, and the radio coverage of the cell is provided by a base transceiver station at the location of the serving base station, i.e. node B, via the Uu interface. One node B typically serves more than one cell and these node bs are controlled by an RNC (radio network controller) which manages the transmission resources of the UTRAN. The node bs communicate with the RNCs via an Iub interface, the RNCs communicate with the core network via an Iu interface, and communication between the RNCs is performed via an Iur interface.

In MBMS according to 3GPP, multimedia information may be transmitted in a broadcast mode or a multicast mode. In the broadcast mode, the same media stream is broadcast to several users simultaneously, regardless of whether any terminal is actually receiving the media stream. In multicast mode, two different transmission schemes may be used, either a point-to-point (PTP) scheme, in which data is transmitted individually to each user using a dedicated traffic channel, or a PTM scheme, in which the same media stream is broadcast on a common channel, which is received simultaneously by a plurality of selected mobile terminals. In PTM mode, duplication of the same content on different radio bearers is avoided and transmission resources are saved, whereas in PTP mode, the transmission power overhead required for transmission on a common channel is avoided.

A network architecture for providing MBMS to several mobile terminal users has joined the MBMS and is located in a cell served by a common node B, which comprises a BM-SC (broadcast/multicast service center) as a source for scheduling MBMS streams for transmission to a Serving GPRS Support Node (SGSN) using suitable transmission means, the SGSN being configured with a Gateway GPRS Support Node (GGSN). A radio network controller RNC monitoring the node B receives an MBMS stream from the SGSN for transmission to the node B via the Iub interface, and a base transceiver station of the node B forwards the MBMS stream via an air interface to MBMS-joined mobile terminals located in the cell served by the node B.

In multimedia services within MBMS of 3GPP, an MBMS cell group (MBMSCG) may be defined in relation to PTM transmission of MBMS data. An MBMS cell group comprises a group of cells sharing the same PDCP (packet data convergence protocol) and RLC (radio link control) within an RNS (radio network subsystem) and is identified by an MBMS cell group identifier (MBMS CG-Id). By means of the MBMSCG-Id all cells of the MBMS cell group are able to receive MBMS data transmitted according to the PTM scheme.

The scheduling of MBMS data transmission is performed by the MAC layer (medium access control layer) of UMTS, more specifically by means of MAC-m functions located within MAC c/sh (common/shared). The same MBMS data block transmitted via the air interface to mobile terminals located in different cells may be scheduled according to a tight (light) scheduling scheme, i.e. scheduled to be transmitted within a limited and relatively small time period. Thus, a mobile terminal receiving the same data block transmitted in more than one cell will be able to use advanced combining techniques to compensate for the power loss of the radio signal during transmission. However, tight scheduling may not always be used for all cells of an MBMS cell group, e.g. due to cell congestion status and scheduling restrictions, etc. The cells within an MBMS cell group that can be scheduled according to a tight scheduling scheme are hereinafter defined as cell group subsets and when an MBMS cell group consists of several cell group subsets, MAC-m buffering may be required. Scheduling according to a tight scheduling scheme of the same MBMS data block to be transmitted approximately simultaneously in cells belonging to the same cell group subset is defined hereinafter as common scheduling.

In the prior art, the same MBMS data block to be transmitted is duplicated in the RNC into one separate FACH data frame (forward access channel data frame) for each cell served by the node B in cells belonging to the same cell group subset and within a limited small time period, e.g. 1TTI (transmission time interval). The RNC sends each individual FACH data frame over the Iub interface resulting in several identical MBMS data blocks being transmitted over the Iub interface to the same node B, i.e. "parallel" Iub transmission. Upon receiving the FACH data frame for each cell, the node B will create a separate MBMS data stream for each cell and transmit on the Forward Access Channel (FACH) for reception by MBMS-joined mobile terminals located within the cell. The transmission between the RNC and the node B via the Iub interface is performed according to the PTP mode, i.e. multimedia service data is transmitted separately between the RNC and the node B, which results in the same multimedia content being transmitted in multiple data frames via the Iub interface and in an inefficient use of transmission resources.

Fig. 3 illustrates an example of the above-mentioned "parallel" Iub transmission according to the prior art, where the same MBMS data block is transmitted 6 times from one RNC through two node bs to 6 cells of a cell group subset of the MBMS service area. Each node B serves 3 cells and the RNC will copy the MBMS data blocks into 6 separate Iub FACH frames for individual transfer via the Iub interface between RNC and node B according to a point-to-point scheme. Once received, each node B will transmit an MBMS data stream on the FACH in 3 cells controlled by the node B if any MBMS-joined mobile terminal is located in it. Since the individual data frames within a cell are independently controlled by the node B before transmission, a relative offset is introduced in the TTI timing within each cell.

Therefore, the prior art involves several drawbacks, such as inefficient use of available Iub transmission resources and relative offsets between cells in timing to TTI in the transmission of the same multimedia service data stream from the radio network controller to multiple cells served by the same base station device and scheduled according to a tight scheduling scheme.

Disclosure of Invention

It is an object of the present invention to enable improved utilization of available Iub transport resources and small relative offsets between cells within the timing to a TTI, thereby providing improved transmission of the same multimedia traffic flow approximately simultaneously from a radio network controller via an Iub interface to mobile terminals located within multiple cells served by the same base station equipment, facilitating the use of advanced combining techniques, such as soft combining. More specifically, it is an object of the present invention to provide an optimized transmission of identical 3GPP MBMS data blocks from a Radio Network Controller (RNC) via an Iub interface to a plurality of cells of a cell group subset served by the same node B approximately simultaneously.

These and other objects are achieved by a method in a radio network controller, by a corresponding method in a base station device, by a radio network controller and by a base station device according to the claims. Independent claims for methods in a radio network controller relate to a method performed in a transmitting node in a common Iub transport and independent claims for methods in a base station relate to a method performed in a respective receiving node in said common Iub transport. The independent claim of the radio network controller relates to the transmitting node in the common Iub transport and the independent claim of the base station device relates to the corresponding receiving node in the common Iub transport.

The claims relate to a method in a Radio Network Controller (RNC) in a radio access network for transferring common multimedia service data blocks between the radio network controller and a base station device via an Iub interface, the base station device serving a plurality of cells in which multimedia service joined mobile terminals are located. The common Iub transport is transmitting the common multimedia service data block, comprising the steps of: storing the common multimedia data block in a separate data frame; and transmitting the separate data frames via an Iub interface to a base station device configured to copy the common multimedia data block into separate multimedia service data streams for each of the plurality of cells.

The claims also relate to a method in a base station device within a radio access network for transferring common multimedia service data blocks received from a Radio Network Controller (RNC) via an Iub interface, said base station device serving a plurality of cells in which multimedia service joined mobile terminals are located. A common Iub transport is transmitting said common multimedia data blocks, comprising the steps of: receiving a separate data frame from a radio network controller, the data frame including the common multimedia data block; storing the common multimedia data block; and copying the common multimedia data block into separate multimedia service data streams for transmission in each of the plurality of cells.

The claims further relate to a Radio Network Controller (RNC) in a radio access network arranged to communicate with a base station device serving a plurality of cells via an Iub interface. The radio network controller comprises means for transmitting common multimedia service data blocks to multimedia service joined mobile terminals located within said cells, said means modifying (adapt) said common multimedia service data blocks into one single data frame and transmitting said single data frame to the base station equipment via the Iub interface for copying and transmission in each of said cells.

The claims also relate to a base station device serving a plurality of cells in a radio access network, arranged to communicate with a Radio Network Controller (RNC) via an Iub interface. The base station equipment comprises means for receiving multimedia service data blocks from said radio network controller and for transmitting multimedia service data streams to mobile terminals located in said cell joining the multimedia service. The apparatus is arranged to receive individual data frames comprising common multimedia service blocks transmitted over an Iub interface and to create individual multimedia service data streams comprising the common multimedia service blocks for transmission in each of the cells.

The transmission of the common multimedia service blocks may be scheduled according to a common schedule.

Said individual data frames transporting said common multimedia service data blocks via the Iub interface may be multimedia service data frames which are transmitted via the Iub interface in combination with non-multimedia service FACH data frames having an indicator for said multimedia service data frames.

Alternatively, said individual data frames transporting said common multimedia service data blocks via the Iub interface may be extended FACH data frames.

The radio access network may be a UTRAN (universal mobile telecommunications terrestrial radio access network), the multimedia service may be a multimedia broadcast/multicast service (MBMS) according to the 3GPP standard, and the base station device may be a node B of the 3 GPP.

Other features and further advantages of the invention will be apparent from the following description and drawings, and from the appended claims.

Drawings

The invention will now be described in more detail and with reference to embodiments and the accompanying drawings, in which:

fig. 1 schematically illustrates a third generation mobile communication system;

fig. 2 schematically illustrates the forwarding of MBMS streams by two RNCs to a plurality of cells served by a node B;

fig. 3 schematically illustrates parallel Iub transport according to the prior art;

fig. 4 schematically illustrates common Iub transport according to the present invention;

fig. 5 illustrates a design (layout) of an MBMS data frame according to a first embodiment of the present invention;

fig. 6 is an example of an MBMS data frame structure according to the first embodiment;

fig. 7 illustrates a prior art FACH data frame;

fig. 8 illustrates a design of a non-MBMS FACH data frame according to a first embodiment of the invention;

fig. 9 is a flowchart of steps included in a first embodiment of an Iub transport procedure according to the present invention;

fig. 10 illustrates a design of an extended FACH data frame according to a second embodiment of the invention; and

fig. 11 is a flowchart of steps in a second embodiment of an Iub transport procedure according to the present invention.

Detailed Description

The terms and expressions used in the specification and claims are intended to have the meanings commonly used by those skilled in the art, and the following abbreviations will be used:

3 GPP: third generation partnership protocol

UTRAN: UMTS radio access network

UMTS: universal mobile communications

MBMS: multimedia broadcast/multicast service

RNC: wireless network controller

BTS: base station transceiver

RRC: radio resource control

RNS: wireless network subsystem

RLC: radio link control

PDCP: packet data convergence protocol

CG: group of cells

FACH: forward access channel

SGSN: serving GPRS support node

CFN: connection frame number

RAN: wireless access network

URA: UTRAN registration area

PTP: point-to-point

And PTM: point-to-multipoint

MCCH: MBMS control channel

MAC: media access control

GPRS (general packet radio service): general packet radio service

PDU: protocol data unit

Fig. 1 illustrates a third generation mobile communication system comprising a core network 1 and a UTRAN3, wherein the core network 1 provides connectivity to external networks 2a and 2b, such as the internet, PSTN (public switched telephone network) or other mobile networks. The core network 1 is also connected via an Iu interface 10 to a UTRAN3 comprising a plurality of RNCs 4a, 4b, 4c, which are interconnected by Iur interfaces 8a and 8 b. Each RNC monitors a plurality of node bs 5a, 5B, 5c, 5d, 5e via the Iub interface 9 and each node B controls radio access within one or more cells 6a, 6B, 6c, 6d, 6e, 6f, 6g, 6 h. The mobile terminals 7 may move between cells and communicate via an air interface 11, i.e. the Uu interface, wherein radio coverage within each cell is provided by a base transceiver station (not shown) of a particular node B.

Fig. 2 schematically shows a conventional node architecture for providing MBMS streams into a plurality of cells, the architecture comprising a BM-SC (broadcast/multicast service center) as a source for scheduling MBMS streams. The MBMS stream is forwarded to the SGSN (serving GPRS support node) via the GGSN (gateway GPRS support node). In this example, two RNCs receive an MBMS stream from an SGSN via an Iu interface for forwarding via an Iub interface to a node B monitored by each RNC for transmission by the node B to MBMS-joined mobile terminals (not shown) located within a cell, with the transmission via the air interface being performed by a BTS (base transceiver station) (not shown) of each cell.

In the prior art, with regard to the transmission of identical MBMS data blocks within cells of a cell group subset served by the same node B, the RNC copies and transmits the MBMS data blocks via the Iub interface in one separate FACH data frame for each cell according to a tightly scheduled transmission scheme, i.e. a transmission performed approximately simultaneously. Thus, several identical MBMS data blocks will be transmitted in separate data frames over the Iub interface to the same node B within a small time interval, i.e. "parallel" Iub transmission of MBMS data blocks, which introduces a timing offset in the TTI between cells.

According to the invention, an improved Iub transmission is achieved by common transmission of identical MBMS data blocks over the Iub interface to be transmitted in a relatively small time interval in a plurality of cells belonging to the same cell group subset, the plurality of nodes being served by the same node B. In case of tight scheduling of identical MBMS data in cells belonging to the same cell group subset and served by the same node B, the solution involves a common Iub transmission of MBMS data blocks from the RNC to the node B. Scheduling according to a tight scheduling scheme of identical MBMS data blocks transmitted approximately simultaneously in cells belonging to the same cell group subset is defined hereinafter as common scheduling. The common MBMS data block is packed into a single data frame, which is transmitted over the Iub interface and received by the node B. The node B replicates the common MBMS data block and creates a plurality of separate data streams, each comprising the common MBMS data block, for transmission on a Forward Access Channel (FACH) within a cell of a cell group subset in which MBMS-joined mobile terminals are located.

In the "parallel" Iub transmission illustrated in fig. 3, the same MBMS data block is transmitted 6 times from one RNC through two node bs to 6 cells of a cell group subset of the MBMS service area. Each node B serves 3 cells and the RNC will copy the MBMS data blocks into 6 separate Iub FACH frames to be transmitted separately via the Iub interface between the RNC and the node B according to a point-to-point scheme. Once received, each node B will transmit an MBMS data stream on the FACH in 3 cells controlled by that node B, which will introduce a relative offset in TTI timing between cells, if any MBMS-joined mobile terminals are located in it. This example illustrates the inefficient use of transmission resources and TTI extension caused by sending 3 identical MBMS data blocks between the same nodes by means of a parallel Iub transport procedure according to the prior art.

Fig. 4 illustrates an embodiment of a common Iub transport procedure according to the present invention, in which a common MBMS data block is transmitted only once in a single data frame via the Iub interface between the RNC and each node B. According to the embodiment illustrated in fig. 4, each node B serves 3 cells and upon reception, each node B will copy the common MBMS data block into separate data streams for transmission in each of the 3 cells served by the node B, which are part of the MBMS cell group subset.

The common Iub transport procedure according to the present invention can be implemented by means of two different schemes. In a first embodiment, the common Iub transport is implemented according to a scheme that introduces MBMS data frames to be transmitted over the Iub interface in combination with the transmission of standard non-MBMS FACH data frames. In a second embodiment, common Iub transmission is implemented according to a scheme that introduces an extended FACH data frame for transmission of common MBMS data.

A first embodiment of the invention introduces an MBMS data frame for transmission of common MBMS data over an Iub interface between an RNC and a node B, wherein the MBMS data is transmitted approximately simultaneously within more than one cell of a cell group subset served by the node B. The design of an MBMS data frame according to the present invention is illustrated in fig. 5, which comprises: a list 21 of cells to which MBMS data is to be transmitted; time 23 for transmitting MBMS data to each cell; a header 25 of a payload (i.e., MBMS data) to be transmitted in each cell; and the payload 27 itself, including the MBMS data. The design in fig. 5 includes only two cells: cell 1 and cell 2, but the number of cells can be much larger, up to 100 cells or even more. Corresponding to the design of fig. 5, fig. 6 illustrates an example structure of an MBMS data frame according to a first embodiment of the invention, the frame in fig. 6 comprising: a list of cells 21, in which only a first cell 21a and a last cell 21b are included; the time to transmit the first cell with the first CFN 23a (connection frame number) and the time to transmit the last cell with the last CFN 23 b; a header of the payload transmitted for the first cell 25a and the last cell 25 b; and an MBMS payload 27. The contents of the other fields of the example structure illustrated in fig. 6 are conventional and need not be described any further.

According to this embodiment of the invention, the non-MBMS FACH data frame is transmitted in combination with the MBMS data frame, i.e. approximately simultaneously with the MBMS data frame. In fig. 7 a prior art FACH data frame structure, e.g. a R99bis-FACH data frame, is shown, comprising a header 31 and a payload 41. The fields of the regular header include: header CRC32 (cyclic redundancy checksum) calculated for the header; FT33 (frame type), which may be data or control; CFN 34 (connection frame number) indicating which downlink radio frame transmits the first data; TFI35 (transport format indicator) indicating the local number of the transport format used for the transmission time interval; and a preferred transmission power level 36 for the respective transport channel during the TTI. The fields of the regular payload 41 include: TB42, 43 (transport block), which are data blocks to be transmitted via the radio interface; a spare extension 44 indicating where the immediate IE (information element) can be added in a backward compatible manner; and a payload CRC45, which is a cyclic redundancy checksum calculated over the payload of the data frame.

The design of a non-MBMS FACH data frame according to the invention is illustrated in fig. 8, comprising a regular header 31 and a payload 41, both described in detail in connection with fig. 7, and further having an MBMS data frame indicator 51. If an MBMS data frame is to be transmitted via the Iub interface in combination with a non-MBMS FACH data frame, i.e. within a limited time interval, the RNC will set an MBMS indicator 51 in the non-MBMS FACH data frame. If the MBMS data frame indicator is set, the node B will combine the MBMS data of the received MBMS data frame with the data received in the non-MBMS FACH data frame.

When the node B receives an MBMS data frame transmitted from the RNC via the Iub interface, it will store therein a payload, i.e., an MBMS data block, and check header information for each cell. Thereafter, the node B will create a FACH data stream comprising MBMS data blocks for each cell in which MBMS data will be forwarded to MBMS-joined mobile terminals. Possible additional headers and other data will be added to the FACH data stream, which is transmitted over the FACH at the time indicated in the CFN field in the MBMS data frame. After transmitting the FACH data stream comprising common MBMS data blocks to all cells indicated in the MBMS data frame, the node B will delete the stored MBMS data blocks.

Fig. 9 is a flowchart of common Iub transport according to the above-described first embodiment of the present invention, in which an MBMS data frame is introduced. The flow chart describes steps performed when a radio network controller receives MBMS data from a core network to be transmitted to a number of MBMS-joined terminals located in a plurality of cells served by a node B controlled by the radio network controller. Common (simultaneous) scheduling may be used for transmissions within cells belonging to the same cell group subset, and the RNC initiates a common Iub transmission procedure in step 200 and creates an MBMS data frame for transmission of common MBMS data blocks via the Iub interface in step 210. In step 220, the RNC sets an MBMS data frame indicator in the non-MBMS FACH data frame to indicate to the receiving node B that the MBMS data frame is to be transmitted in combination with the non-MBMS FACH data frame. A non-MBMS FACH data frame is transmitted to the node B via the Iub interface in step 230 and an MBMS data frame is transmitted to the node B in step 240. Upon receiving the MBMS data frame, the node B will store and copy the MBMS data blocks of the MBMS data frame and create separate FACH data streams including common MBMS data blocks for each cell in which the MBMS-joined mobile terminals are located, step 260. In step 270 the node B transmits a separate FACH data stream over the air interface in each cell.

A second embodiment of the invention implements a common Iub transport from RNC to nodeb by means of an updated extended FACH data frame, and the design of the extended FACH data frame according to the invention is illustrated in fig. 10. The extended FACH data frame conveys common MBMS data to be transmitted in separate FACH streams in different cells belonging to one cell group subset and served by the node B. The extended FACH data frame includes a first loop (loop)61 of all FACH streams to be transmitted, which indicates the cell ID, facid, TFI (transmission power level) and CFN as well as the payload and other transport blocks (e.g., non-MBMS data blocks) to be transmitted in the cell by each FACH stream looped over. The extended FACH data frame also includes a second loop 63 with a header for each common MBMS data block to be transmitted in each FACH stream, indicating a reference ID and MAC-m header for each MBMS data block of the loop. The extended FACH data frame further comprises a third loop 65 with a payload of MBMS data blocks to be transmitted, which indicates for each MBMS data block the TB (transport block) number, the length of the TB, and the content of the TB.

When the node B receives an extended FACH data frame transmitted over the Iub interface, the node B will create an independent FACH data stream to be transmitted in each of said cells. The node B will append the correct MAC-m to the corresponding MBMS data block and transmit these blocks simultaneously with the non-MBMS data blocks by transmitting separate FACH data streams in each cell over the air interface to be received by MBMS-joined mobile terminals located within the cell.

Fig. 11 shows a flow chart of a common Iub transmission according to the above-described second embodiment of the present invention, wherein a common MBMS data block is transmitted over the Iub interface by means of an extended FACH data frame, as illustrated in fig. 10. The flow chart describes the steps performed when the radio network controller receives MBMS data from the core network to be transmitted to a number of MBMS-joined terminals located in a number of cells served by node bs controlled by the radio network controller. Common (i.e. tight) scheduling may be used for transmissions to cells belonging to the same cell group subset, and the RNC initiates a common Iub transmission procedure in step 400 and creates an extended FACH data frame to include the common MBMS data blocks to be transmitted over the Iub interface in step 410. At step 420, the RNC sends an extended FACH data frame to the node B. Upon receiving the extended FACH data frame, the node B stores and copies the MBMS data blocks of the extended FACH data frame and creates a separate FACH data stream for each cell in step 430. In step 440, the BTS of the node B transmits a separate FACH data stream in each cell to be received by MBMS-joined mobile terminals located therein.

By employing common Iub transmission of identical MBMS data according to the present invention, a more efficient use of Iub transmission resources and a "tighter" scheduling is achieved if more than one cell served by one node B will receive the identical and common MBMS data approximately simultaneously, thereby facilitating the use of advanced combining techniques when a mobile terminal receives identical data blocks from more than one BTS, i.e. transmitted in more than one cell.

The present invention has been described with reference to specific exemplary embodiments and drawings for the purpose of illustrating the inventive concepts only, and the invention is not limited to the disclosed embodiments. Instead, the invention is intended to cover various modifications within the scope of the appended claims.

Claims (16)

1. A method in a radio network controller, RNC, (4a-c) within a radio access network (3) for transmitting common multimedia service data blocks via an Iub interface (9) between the radio network controller and a base station equipment (5a-e) serving a plurality of cells (6a-h) in which multimedia service joined mobile terminals (7) are located, wherein a common Iub transport is used for transmitting said common multimedia service data blocks, characterized by the steps of:

-storing (210, 410) the common multimedia service data block in separate data frames; and

-transmitting (240, 420) the individual data frames via an Iub interface to a base station device configured to copy the common multimedia service data block into independent multimedia service data streams for each of the plurality of cells,

wherein transmission of the common multimedia service data block in the cell is scheduled according to a tight scheduling scheme,

wherein the multimedia service is a multimedia broadcast/multicast service MBMS according to a 3GPP standard;

wherein the tight scheduling scheme refers to the same common multimedia broadcast/multicast service MBMS data blocks being transmitted approximately simultaneously in cells belonging to the same cell group subset.

2. A method in a radio network controller according to claim 1, c h a r a c t e r i z e d i n that the separate data frame transporting the common multimedia service data block over the Iub interface is a multimedia service data frame which is transmitted over the Iub interface in combination with a non-multimedia service FACH data frame having an indicator for the multimedia service data frame.

3. Method in a radio network controller according to claim 1, characterised in that the separate data frame transporting the common multimedia service data block over the Iub interface is an extended FACH data frame.

4. A method according to any of claims 1-3, wherein said radio access network is a universal mobile telecommunications terrestrial radio access network, UTRAN, and said base station equipment is a node B of the 3 GPP.

5. A method in a base station equipment (5a-e) within a radio access network (3) for transmitting common multimedia service data blocks received from a radio network controller, RNC, (4a-c) via an Iub interface (9), said base station equipment serving a plurality of cells (6a-h) in which multimedia service joined mobile terminals (7) are located, wherein a common Iub transmission is used for transmitting said common multimedia service data blocks, characterized by the steps of:

-receiving a separate data frame from a radio network controller, the data frame comprising the common multimedia service data block,

-storing said common multimedia service data block, and

-copying (260, 430) the common multimedia service data block into separate multimedia service data streams for transmission (270, 440) in each of the plurality of cells,

wherein transmission of the common multimedia service data block in the cell is scheduled according to a tight scheduling scheme,

wherein the multimedia service is a multimedia broadcast/multicast service MBMS according to a 3GPP standard;

wherein the tight scheduling scheme refers to that the same common multimedia broadcast/multicast service MBMS data blocks are transmitted at the same time in close proximity in cells belonging to the same cell group subset.

6. A method in a base station equipment according to claim 5, characterized in that the individual data frames transporting the common multimedia service data blocks over the Iub interface are multimedia service data frames, which are transmitted over the Iub interface in combination with non-multimedia service FACH data frames having indicators for the multimedia service data frames.

7. Method in a base station arrangement according to claim 5, characterised in that the individual data frames transporting the common multimedia service data blocks via the hb interface are extended FACH data frames.

8. A method according to any of claims 5-7, wherein said radio access network is a Universal Mobile Telecommunications terrestrial radio Access network, UTRAN, and said base station equipment is a node B of 3 GPP.

9. A radio network controller, RNC, (4a-c) in a radio access network (3) arranged to communicate via an Iub interface (9) with a base station equipment (5a-e) serving a plurality of cells (6a-h), the radio network controller comprising means for transmitting common multimedia service data blocks via the base station equipment and the Iub interface to multimedia service joined mobile terminals (7) located in said cells,

-means for storing said common multimedia service data blocks as individual data frames; and

-means for transmitting said individual data frames to a base station device via an Iub interface for replication and transmission in each of said cells,

wherein transmission of the common multimedia service data block in the cell is scheduled according to a tight scheduling scheme,

wherein the multimedia service is a multimedia broadcast/multicast service MBMS according to a 3GPP standard;

wherein the tight scheduling scheme refers to the same common multimedia broadcast/multicast service MBMS data blocks being transmitted approximately simultaneously in cells belonging to the same cell group subset.

10. The rnc of claim 9 wherein the separate data frame is a multimedia service data frame adapted to be transmitted over an Iub interface in combination with a FACH data frame having an indicator for the multimedia service data frame.

11. The radio network controller according to claim 9, characterized in that the separate data frame is an extended FACH data frame.

12. The radio network controller according to any of claims 9-11, wherein the radio access network is a universal mobile telecommunications terrestrial radio access network, UTRAN, and the base station equipment is a node B of a 3 GPP.

13. A base station equipment (5a-e) serving a plurality of cells (6a-h) in a radio access network (3), arranged to communicate with a radio network controller, RNC, (4a-c) via an Iub interface (9), the base station equipment comprising means for receiving common multimedia service data blocks from said radio network controller and for transmitting multimedia service data streams to multimedia service joined mobile terminals (7) located in said cells, characterised in that,

-means for receiving a separate data frame comprising common multimedia service data blocks transmitted over the Iub interface; and

-means for creating separate multimedia service data streams comprising said common multimedia service data block for transmission in each of said cells,

wherein transmission of the common multimedia service data block in the cell is scheduled according to a tight scheduling scheme,

wherein the multimedia service is a multimedia broadcast/multicast service MBMS according to a 3GPP standard;

wherein the tight scheduling scheme refers to the same common multimedia broadcast/multicast service MBMS data blocks being transmitted approximately simultaneously in cells belonging to the same cell group subset.

14. A base station device according to claim 13, characterized in that said separate data frame is a multimedia service data frame adapted to be transmitted via the Iub interface in combination with a FACH data frame having an indicator for said multimedia service data frame.

15. The base station apparatus of claim 13, wherein the separate data frame is an extended FACH data frame.

16. A base station device according to any of claims 13-15, wherein said base station device is a node B of 3GPP and said radio access network is a universal mobile telecommunications terrestrial radio access network, UTRAN.