WO2005018116A1

WO2005018116A1 - Method for establishing common transport channel for mbms

Info

Publication number: WO2005018116A1
Application number: PCT/KR2004/002088
Authority: WO
Inventors: Sung-Ho Choi; Chunying Sun; Xiaoqiang Li
Original assignee: Samsung Electronics Co., Ltd.; Beijing Samsung Telecom R & D Center
Priority date: 2003-08-19
Filing date: 2004-08-19
Publication date: 2005-02-24
Also published as: CN1585316A; KR20060120591A

Abstract

The method for establishing common channel for MBMS service comprising steps of: reconfiguring a common transport channel and informing a Node B and a UE of the time of activating by a RNC; reconfiguring the common transport channel and its physical channel by the Node B, and activating them at the specified time; and configuring the common transport channel by the UE and activating it at the specified time. A novel mechanism for notifying the Node B and the UE of configuring the common transport channel is provided in the present invention, so that the multiplexing of several MBMS services is possible, and the network resources can be utilized for the MBMS service reasonably and efficiently.

Description

METHOD FOR ESTABLISHING COMMON TRANSPORT CHANNEL FOR MBMS

BACKGROUND OF THE INVENTION

1. Field of the Invention This invention relates to 3^rd Generation (3G) mobile communication system, especially to a method for establishing common transport channel for MBMS.

2. Description of the Related Art MBMS is a new service under standardization by 3^rd Generation Mobile Communication System Partnership Project (3GPP). The MBMS service is an unidirectional point -to-multipoint (p-t-m) (i.e. multimedia data sent from a single data source are transferred to multiple users through network transmission) service. Most remarkable feature of the service is that it can make use of radio resources and network resources efficiently. The MBMS service is mainly used in wireless communication network system, e.g. Wideband Code-Division Multiple Access system, Global System of Mobile Communication, etc. The transmission of the MBMS service data basically includes following several steps, i.e. data source sending, middle network transmission, destination cell on-the-air transmission and user reception. Figure 3 is a logical figure for network devices of the radio communication system that can provide the MBMS service, in which the MBMS actually makes use of General Packet Radio Data Service (hereinafter referred to as GPRS) as core transmission network. As shown in Figure 3, Broadcast and Multicast Service Center (hereinafter referred to as BM-SC) 301 is the data source for the MBMS data transmission. Gateway GPRS Supporting Node (hereinafter referred to as GGSN) 302 is used to connect the GPRS network with the external network (such as INTERNET). Gateway GPRS Supporting Node 302 is used to connect BM-SC 301 in the MBMS service and to send MBMS data to specific Service GPRS Supporting Node (hereinafter referred to as SGSN) 303. Cell Broadcast Center (hereinafter referred to as CBC, Not shown) is the data resource of the cell broadcast, through interconnecting the CBC with the BM-SC 301 in the MBMS, the CBC can provide the MBMS service with declaration function. The SGSN 303 is used to perform access control on a UE as well as mobility management by accessing a home Location register (hereinafter referred to as HLR) 306, and sends the MBMS data from the GGSN 302 to the specific Radio Network Controller (hereinafter referred to as RNC) 304 at the same time. The RNC 304 is used to control a group of base stations (hereinafter referred to as NODE B, Not shown) and sends multimedia data to the specific NODE B. The NODE B (base station) establishes air physical channel for the MBMS service in a certain cell under the control of the RNC 304. Terminal User Equipment (hereinafter referred to as UE) 305 is the terminal equipment for MBMS data reception. The UE 305 communicates with the RNC 304 via interface Uu 107. Figure 4 gives the whole process from service declaration, user joining, service notification, radio bearer establishment to user's final leaving in the MBMS service. 401 Subscription - establishing the connection between a user and a service provider, and an authorized user may receive the relevant MBMS service. 402 Service Announcement - notifying the user of services that will be provided. For example, the system will broadcast a football match in Beijing at 7:00 p.m. 403 Joining - indicates that the user joining a group, i.e. the user informs the network that he or she is willing to receive this multicast service. 404 MBMS Session Start - indicates that establishing the network resources for the MBMS data transmission. 405 MBMS notification - indicates that notifying the user of the MBMS data transmission that will be performed right away. 406 Data transmission - indicates the process of transferring the MBMS service data to the user. 407 MBMS Session Stop - indicates that releasing the network resources after the MBMS data transmission is completed. 408 Leaving - corresponding to the joining of 403 , which indicates that the user is leaving a group, i.e. the user doesn't want to receive the data of a certain service any more. In conventional WCDMA system, such three downlink common transport channels as downlink Forward Access Channel (FACH), Paging Channel (PCH) and Broadcast Channel (BCH) have been established. Among those three channels, only the FACH can be used for user data transmission, while the PCH and the BCH are used for signaling transmission. Therefore, the process of establishing the FACH is explained hereinafter. Figure 7 illustrates the process of establishing the common transport channel of FACH in the conventional system. To establish the FACH transport channel, an S-CCPCH channel must be established to bear the said FACH, since the FACH is mapped on the S-CCPCH.

And one S-CCPCH can certainly contain several FACH channels. All these

FACHs are borne on the said S-CCPCH through multiplexing the transport channel. Message "Common Transport Channel Setup Request" at 701 contains parameters of the FACH to be established and physical parameters of the S-CCPCH to be established. When the Node B receives this message, it pre-allocates the relevant network resource and replies with a message of 702

"Common Transport Channel Establishment Response", which contains parameters of FACH in the Node B side. After the RNC succeeds in establishing the FACH/S-CCPCH, it transmits a 703 "Downlink Synchronization" control frame through the user plane established. When the Node B receives this frame, it transmits a 704 "Uplink Synchronization" control frame to the RNC. Through the interaction between the 703 and the 704, the synchronization between the RNC and the Node B can be realized so as to ensure the time that the uplink and downlink user data frames spent in being transmitted to the other sides be within a certain range. After the RNC acknowledges that the user plane of FACH are synchronized, it transmits a message of 705 "System Information Update Request" to the Node B, in which the system information index that RNC notifies the base station to update is contained, thus the corresponding system information 5/6 can be well updated in the base station. The RNC receives a message of 706 "System Information Update Response" from the Node B. The RNC sends a message 707 to the UE to inform that the corresponding system information has been modified, and indicates that the UE should read out the system information to learn about the up-to-date information of FACH/S-CCPCH. Modification of the Common channels multiplexing in layer of transport channel is not supported in the prior art, if the modification of an existing FACH channel is needed, it is necessary to delete the older channels to release the resource for establishing a new one according to the new configuration parameters. The FACH channel is a channel shared by all users within a certain cell. To guarantee that all users could receive information via this channel, it is necessary to configure the channel according to the performance of the poorest user equipment; therefore, it is imperfect in high data rate supporting. It is inadequate to transfer the MBMS service whose data rate is comparatively high via the existing FACH, thus, it is necessary to establish a new channel or reconfigure an existing one for the MBMS service. By the available rule that the UE receives information via the FACH, the UE selects the corresponding FACH/S-CCPCH according to its IMSI (International Mobile Subscriber Identity). However, it is impossible for the MBMS service data to transfer the MBMS data on each FACH/S-CCPCH configured by the system. Therefore, it is necessary to adopt a new method to inform the UE of information on FACH/S-CCPCH configuration.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method for establishing common transport channel for MBMS service, with this method, an existing common channel can be reconfigured for the MBMS service, or a new common one can be established for the MBMS service specially. To realize above object, a method for establishing common channel for

MBMS service comprising steps of: reconfiguring a common transport channel and informing a Node B and a UE of the time of activating by a RNC; reconfiguring the common transport channel and its physical channel by the Node B, and activating them at the specified time; and configuring the common transport channel by the UE and activating it at the specified time. A novel mechanism for notifying the Node B and the UE of configuring the common transport channel is provided in the present invention, so that the multiplexing of several MBMS services is possible, and the network resources can be utilized for the MBMS service reasonably and efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the process of establishing MBMS common channel; Figure 2 shows the actions of the RNC node; Figure 3 is the illustration of the MBMS system structure; Figure 4 is the flowchart of the MBMS multicast service; Figure 5 shows the actions of the Node B node; Figure 6 shows the actions of the UE node; and Figure 7 illustrate the method for establishing the common channel.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, the correct examples of this invention will be explained in detail with reference to figures, and only the necessary part of this specification will be explained in the following and other parts will be omitted for emphasis. Figure 1 shows the process of establishing MBMS common transport channel. The RNC receives message 101 "Session Start" from the SGSN, in which the MBMS service identifier and the required QoS parameters are contained. In general, the QoS parameters include information on service identifier, required bandwidth, maximum data rate, guaranteed data rate, transport delay and so on. Since it is possible that the RNC has established the context for this service before the session starts, this context contains the service identifier and the identifier list of the UEs in connected state. The RNC judges whether the number of users iri connected state is greater than the switching threshold, if so, the process skips 102 to 103. In order to utilize the resource of on-the-air interface reasonably and effectively, the switching threshold from the point-to-point channel to the point-to-multipoint one is set to the RNC in the MBMS system. 102 the RNC transmits the paging message to the UE, and the UE establish the connections with the core network. The SGSN informs the RNC of UE's identifiers to help the RNC in user counting. After completing the process of user counting, the RNC determines whether to support the point-to-point channel or the point-to-multipoint one. Here, it is supposed that the counted number of users be greater than the switching threshold and the point-to-multipoint transport mode be determined to support. According to the QoS parameters and the utilization of the controlled cell's radio resources, the RNC determines whether to utilize the existing FACH/S-CCPCH through the broadcast in the system information to support this MBMS service (this procedure is realized at step 105), or to reconfigure the FACH/S-CCPCH in the system information (this procedure is realized at step 107), or to establish a new dedicated FACH/S-CCPCH for the MBMS service (this procedure is realized at step 113), or to reconfigure the existing FACH/S-CCPCH that is dedicated for the MBMS service (this procedure is realized at step 123). If the RNC determines to utilize the existing FACH/S-CCPCH through the broadcast in the system information to support this MBMS service (this procedure is realized at step 105), the users who have joined in the MBMS service know the MBMS channel's configuration parameters when they receive a message of 106 "MBMS Radio Bearer Setup". This message contains information on PDCP information, Radio Bearer Mapping information, transport channel, physical channel, transport format combination set and so on. Also, it can contains only information on the PDCP information, the Radio Bearer Mapping information and the index order that the FACH/S-CCPCH locates in the system information. If the RNC finds out that the attribute of the existing FACH/S-CCPCH can not meet the QoS demand of the MBMS and determines to reconfigure the FACH/S-CCPCH broadcast in the system information (this procedure is realized at step 107), the RNC transmits the request of reconfiguring the common channel (this procedure is realized at step 108) to the Node B, and this request message contains information on the relevant parameters of FACH transport channels that are to be added or reconfigured, new transport format combination set, new parameters of physical channel and the time for activating. The time for activating can be the system frame number when the physical channel is being activated. If the Node B supports these configurations, it replies the RNC with a message of 109 "Common Transport Channel Reconfiguration Response". Because this new configuration requires to be broadcast in the system information to inform all users, the RNC transmits the message of 110 "System Information Update Request" to the Node B, in which the content of SIB 5/6 to update is contained. The RNC informs all users to read out the updated system information at step 111, transmits the message of "Paging 1" to the user equipments in CELL_PCH, URA PCH and IDLE states, and a message of "System Information Change Indication" to those in CELL FACH state. When these user equipments receive the corresponding messages of "System Information Change Indication" and "Paging 1", they update the system information according to the prior art. The RNC transmits the message of 112 "MBMS Radio Bearer Setup" to MBMS users, which contains the configuration information on the service identifier, the PDCP information, the Radio Bearer Mapping information, the transport channel, the physical channel, the transport format combination set and so on. Also, it can contains only the information on the service identifier, the PDCP information, the Radio Bearer Mapping information and the index order that the FACH/S-CCPCH locates in the system information_"

If the RNC finds out that the existing FACH/S-CCPCH does not support this MBMS service, or for some other reasons, it determines to establish a new common transport channel and physical channel that are dedicated for this MBMS service. The process of establishing FACH/S-CCPCH is described from step 114 to 117, which is just the same as that of the prior art. Then the information on FACH/S-CCPCH is transferred to the MBMS users via the MCCH, while those non-MBMS users can not capture this information. The message of 118 "MBMS Radio Bearer Setup" contains information on the service identifier, the PDCP information, the Radio Bearer Mapping information, the transport format of FACH, the parameters of S-CCPCH and the time for activating. When the UE receives this message, it configures the corresponding Radio Bearer, the physical layer and the transport layer, and activates this physical channel at the time specified by the RNC for receiving MBMS data. 119 If another MBMS service is coming, the RNC first judges its transport channel's type, and if it is point-to-multipoint, the RNC determines to utilize the existing dedicated MBMS common channel. The RNC reconfigures the established FACH/S-CCPCH through transmitting a message of 124 "Common Transport Channel Reconfiguration Request", in which information on the parameters of transport channel, the parameters of physical channel, the new TFCS, the frame number of system information and so on are contained. The frame number of system information indicates the time when the Node B should activate the new configuration. The Node B transmits a message of 125 "Common Transport Channel Reconfiguration Response" to notify the RNC of the channels that the RNC requires have been reconfigured already. Step 126 and step 127 synchronize the uplink and downlink user interfaces between the Node B and the RNC. The RNC transmits a message of 128 "MBMS Radio Bearer Reconfigure" to notify the original UE to reconfigure the parameters of radio bearer, and this message contains the new parameters of the transport channel and the physical channel, the new TFCS and the time for activating. At step 129, the RNC notifies the user equipments of new service to receive their required MBMS radio bearer parameters, to configure corresponding transport channel, the physical channel, the radio bearer parameters and the time for activating. The time for activating is used for notifying the user equipment when to activate the new configuration parameters of the channels.

1) node process flow of the RNC Figure 2 shows the node process flow of the RNC. At phase 201, the RNC establishes the point-to-multipoint channel for the MBMS service. At phase 202, the RNC judges whether to utilize the existing Common channel broadcast in the system information to support the MBMS service or not, if so, the process goes to 203 and the RNC transmits the message of "MBMS Radio Bearer Setup" to UEs; if not, the process goes to 204. At phase 204, it is to judge whether the RNC should reconfigure the Common channel which should be broadcast in the system information to support the MBMS service or not, if so, the process goes to 205; if not, goes to 211. At phase 205, the RNC transmits the "Common Transport Channel Reconfiguration Request" message to the Node B. When receiving the message of "Common Transport Channel Reconfiguration Response" from the Node B at step 207, the RNC updates the system information in the Node B. At phase 208, the RNC updates the system information, and this procedure is realized by transmitting the message of "System Information Update Request" to the Node B and receiving the message of " System Information Update Response" from the Node B. At phase 209, the RNC informs the UE to update the system information, transmits the message of "Paging 1 " to the user equipments in CELL PCH, URA PCH and IDLE states, and the message of "System Information Change Indication" to the those in CELL_FACH state so as to let these user equipments update the system information. At phase 210, the RNC transmits the message of "MBMS Radio Bearer Setup" to the MBMS user equipments that are monitoring the MCCH logic channel. At phase 211, it is to judge whether the RNC should establish the Common channel that is dedicated for MBMS service or not, if so, the process goes to 212; if not, goes to 216. At phase 212, the RNC transmits the message of "Common Transport Channel Setup Request" to the Node B. When receiving the response from the Node B at 214, the RNC conducts the synchronization of the lub user interface. After completing the synchronization process, the RNC learns about that the Common channel has been successfully established. Then it transmits the message of "MBMS Radio Bearer Setup" to the UE. At phase 216, it is to judge whether the RNC should reconfigure the existing the common channel that is dedicated for MBMS service or not, if so, the process goes to 217; if not, goes to 201. At phase 217, the RNC transmits the message of "Common Transport Channel Reconfiguration Request" to the Node B. When receiving the message of "Common Transport Channel Reconfiguration Response" from the Node B at 219, the RNC transmits the message of "MBMS Radio Bearer Setup" and "MBMS Radio Bearer Reconfigure" to the UE at 220. Node process flow of the Node B Figure 5 shows the node process flow of the Node B. At phase 501, the Node B receives messages from the RNC via interface lub. At phase 502, it is to judge whether the message that the Node B receives is the "Common Transport Channel Setup Request" or not, if so, the process goes to

503; if not, goes to 505. At phase 503, the Node B allocates resource for the

Common channel to be established. After succeeding in establishing the Common channel, it transmits the message of "Common Transport Channel Setup Response" to the RNC. At phase 505, it is to judge whether the Node B has received the message of

"System Information Update Request" or not, if so, the process goes to 506; if not, goes to 508. At phase 506, the Node B updates the system information according to the request from the RNC and replies the RNC with the message of "System

Information Update Response". At phase 508, it is to judge whether Node B has received the message of "Common Transport Channel Reconfiguration Request" or not if so, the process goes to 509; if not, goes to 501. At phase 509, the Node B reconfigures the transport channel and the physical channel according the request from the RNC, and activates the transmission of downlink signal at the time specified by the RNC. At phase 510, the Node B transmits the message of "Common Transport Channel Reconfiguration Response" to the RNC. 1) node process flow of the UE Figure 6 shows node process flow of the UE. At phase 601, the UE receives messages from the RNC via interface Uu. At phase 602, it is to judge whether the message that the UE has received from the RNC is the message of "MBMS Radio Bearer Setup" or not, if so, the process goes to 603; if not, goes to 604. At phase 603, the UE configures the channel according to the parameters given by the RNC, and activates it at the time specified by the RNC. At phase 604, it is to judge whether the message that UE has received from the RNC is about to update the system information or not, if so, the process goes to 605; if not, goes to 601. At phase 605, the UE reads out the new system information and configures the transport channel and the physical channel according to configuration parameters in the system information at phase 606. At phase 607, the UE receives the MBMS data via the configured MBMS channels.

Claims

WHAT IS CLAIMED IS: 1. A method for establishing common channel for MBMS service comprising steps of: reconfiguring a Common transport channel and informing a Node B and a UE of the time for activating by a RNC; reconfiguring the Common transport channel and its physical channel by the Node B, and activating them at the specified time; and configuring the Common transport channel by the UE and activating it at the specified time.

2. The method according to Claim 1, wherein the message of "Common Channel Reconfiguration Request" that the RNC transmits to the Node B contains information on "Transport Format Combination Set", "Time for Activating", "New Information on Transport Channel" and "Information on Reconfigured Physical Channel".

3. The method according to Claim 1, wherein the message of "MBMS Radio Bearer Setup" and the message of reconfiguration which the RNC transmits to the UE contain "Time for Activating, New Information on Transport Channel, Information on Reconfigured Transport Channel, and Information on Reconfigured Physical Channel.

4. A method for establishing a common channel for MBMS(Multimedia Broadcast and Multicast Service) service comprising steps of: informing a Node B and a UE of an information about the common channel for the MBMS service by a RNC to configure the Common channel, when the MBMS service need to configure a point to multipoint(PtM) connection; configuring physical channel of the common channel by the Node B; and configuring the Common channel by the UE base on the information about the common channel.

5. A method of the claim 4, wherein the information is transmitted on other common channel to the UE.

6. A method of the claim 5, wherein the PtM connection is determined based on the number of UE which request the MBMS service.