JP7369527B2 - Multicast distribution system and core network node equipment - Google Patents

Description

The present invention relates to a multicast distribution system that includes mobile terminals such as mobile terminals, and particularly in LTE (Long Term Evolution) systems, etc., the multicast data distribution function is implemented using a network that is simpler than eMBMS (evolved Multimedia Broadcast Multicast Service). The present invention relates to a multicast distribution system for realizing the configuration and a core network node device used therein.

In 3GPP (Third Generation Partnership Project), which is a standardization project for mobile communication systems, MBMS (Multimedia Broadcast Multicast Service) has been specified in order to provide multicast/broadcast services. In current MBMS, multicast data is transmitted in area units of MBSFN (Multicast-Broadcast Single-Frequency Network) consisting of multiple cells via PMCH (Physical Multicast Channel), which is a physical channel dedicated to multicast. transmission). In this case, a multicast bearer, which is a radio bearer exclusively for multicast, is constructed between the radio base station and the mobile terminal, and multicast data is distributed to each mobile terminal via the multicast bearer (Patent Documents 1 and 2). .

Furthermore, in the method disclosed in Patent Document 3, paragraph 0045 states, "Furthermore, the base station device 12 notifies the terminal 13 of the radio channel using an MBMS Radio Channel Indication message." , as disclosed in Patent Document 1 and Patent Document 2, as stated in paragraph 0077, "The transport bearer for MBMS data can be identified by an IP multicast address." This is a distribution method using multicast bearers similar to .

Japanese Patent Application Publication No. 2013-146109 Japanese Patent Application Publication No. 2018-113706 Patent No. 5641088

However, in order to perform multicast distribution using multicast bearers, not only the core network and wireless base stations, but also mobile terminals must be equipped with MBMS-specification radio interfaces, that is, radio interfaces that are capable of constructing multicast bearers. No. Since the MBMS service in 3GPP has only recently been shared, the spread of MBMS-compatible mobile terminals has not caught up, and users who only own mobile terminals that do not support MBMS are unable to distribute multicast data. There are problems that you can accept and cannot accept.

An object of the present invention is to provide a multicast distribution system that can distribute multicast data received by a wireless base station from a core network without any problem even to mobile terminals that are not compatible with MBMS, without increasing the processing load on core network node devices, and a core used therein. An object of the present invention is to provide a network node device.

In order to solve the above problems, the multicast distribution system of the present invention is characterized by being configured as follows. That is, the multicast distribution system includes a core network node device, a wireless base station connected to the core network node device via a physical line, and a mobile terminal wirelessly connected to the wireless base station. The mobile terminal is configured to be able to distribute multicast data compliant with MBMS (Multimedia Broadcast Multicast Service) to mobile terminals. The core network node device includes a multicast participation reception unit that receives a multicast group participation request from a mobile terminal by receiving the group IP address of the multicast group from the mobile terminal via a wireless base station, and Build individual unicast bearers between the multicast participation list registration unit that registers in the multicast participation list, the multicast data reception unit that receives multicast data distributed from the upper network, and the mobile terminals registered in the multicast participation list. A unicast bearer construction instruction transmitting section that transmits a unicast bearer construction instruction to a wireless base station to perform a unicast bearer construction instruction, and a multicast proxy section that has a multicast data transfer section that transfers multicast data to the wireless base station are provided. In addition, the radio base station also has individual communication between a unicast bearer construction instruction receiving unit that receives the unicast bearer construction instruction and mobile terminals that have received the unicast bearer construction instruction and are registered in the multicast participation list. A unicast bearer construction section that constructs a unicast bearer, and a multicast data transmission section that transmits multicast data to a mobile terminal via the unicast bearer are provided. Then, the multicast data is distributed and transmitted from the core network node device via the wireless base station to the mobile terminals registered in the multicast participation list via individual unicast bearers.

The core network node device of the present invention also includes a multicast participation reception unit that receives a multicast group participation request from a mobile terminal by receiving a group IP address of the multicast group from the mobile terminal via a wireless base station; A separate unit is established between the multicast participation list registration unit that registers group participation requests in the multicast participation list, the multicast data reception unit that receives multicast data distributed from the upper network, and the mobile terminals registered in the multicast participation list. A multicast proxy unit includes a unicast bearer construction instruction transmitter that transmits a unicast bearer construction instruction for constructing a cast bearer to a wireless base station, and a multicast data transfer unit that transmits multicast data to the wireless base station. It is characterized by being equipped.

In the multicast distribution system of the present invention, a core network node device is provided with a multicast participation list registration unit that receives and registers multicast group participation requests from mobile terminals. Additionally, the core network node device instructs the wireless base station to individually construct a unicast bearer with the mobile terminal that has requested to join the multicast group, and also transmits the multicast data received from the upper network. A multicast proxy unit is provided for forwarding to the wireless base station. The multicast data is distributed and transmitted from the core network node device via the radio base station to the mobile terminals registered in the multicast participation list via the above-mentioned individual unicast bearers. With this configuration, a unicast bearer is used as a radio bearer to transmit multicast data between a radio base station and a mobile terminal, and even mobile terminals that are not compatible with MBMS and cannot construct a multicast bearer can receive multicast data without problems. It becomes like this.

1 is a block diagram of a multicast distribution system that is an embodiment of the present invention. FIG. 2 is a block diagram of a core network node device. FIG. 2 is a block diagram of an eNodeB (radio base station). FIG. 2 is a block diagram of a UE (mobile terminal). A conceptual diagram of an IP packet. FIG. 2 is a diagram conceptually showing a 3GPP control plane protocol stack. FIG. 2 is a diagram conceptually showing a 3GPP user plane protocol stack. FIG. 3 is a diagram conceptually showing downlink channel mapping in the present invention. Conceptual diagram of resource blocks. The communication flow diagram which shows the flow of processing when a UE attaches to a core network. FIG. 3 is a communication flow diagram showing the flow of processing for registering a UE to a multicast group in the multicast distribution system of the present invention. FIG. 3 is a communication flow diagram of processing for performing data streaming using individual unicast bearers to registered UEs in the multicast distribution system of the present invention. FIG. 3 is a communication flow diagram of a process in which a UE that has completed data streaming leaves a multicast group in the multicast distribution system of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described based on the accompanying drawings.
FIG. 1 is a block diagram showing the overall configuration of a multicast distribution system that is an embodiment of the present invention. The multicast distribution system 1 is configured as an advanced wireless communication network according to 3GPP (Third Generation Partnership Project) specifications, specifically an LTE system. The main parts of the network are a core network (or EPC: Evolved Packet Core), eNodeB4 which is a radio base station, and E-UTRAN7 (Evolved Universal Terrestrial Radio Access Network) which is a physical line network that connects these. A plurality of UE5 (User Equipment: mobile terminals) are wirelessly connected to the eNodeB4. Furthermore, although not shown, the E-UTRAN 7 includes an X2 line for handover for connecting the eNodeB4 to other eNodeB4s.

A core network node device 3 is provided in the core network (EPC). As described later, in the present invention, a multicast proxy section 3c is functionally incorporated into the core network node device 3. In this embodiment, the multicast proxy section 3c is constructed to implement a proxy function compliant with version 3 (IGMPv3) of IGMP (Internet Group Management Protocol).

The eNodeB 4 is connected to the core network node device 3 via the E-UTRAN 7. Then, in the core network node device 3, the multicast proxy unit 3c receives the multicast data constituting the distributed content from the media server 6 via the multicast router 8, and also sends the multicast data from the core network node device 3 to the UE 5 via the eNodeB4. , multicast data compliant with MBMS (evolved Multimedia Broadcast Multicast Service) is distributed via individual unicast bearers 12.

Multicast router 8 plays the role of distributing multicast data transmitted from media server 6 to a plurality of core network node devices 3. Specifically, it includes a proxy list registration unit 8a for receiving a multicast participation request from a core network node device 3 as a connection destination and registering the core network node device 3 in a proxy list. The multicast data is distributed only to the core network node devices 3 that have been accessed. Note that if only one core network node device 3 is installed, the multicast router 8 can be omitted.

FIG. 2 is a block diagram showing an example of the configuration of the core network node device 3. As shown in FIG. The core network node device 3 includes a control unit 3a configured with an MPU (Micro Processor Unit), an upper-side transmitting/receiving unit 3k for receiving multicast data from the media server 6 via the multicast router 8, and a core side transmitting/receiving unit 3k. It has a hardware configuration in which a transmitting/receiving section 3f is connected via a bus. The core-side transmitting/receiving unit 3f is for transmitting and receiving unicast data and multicast data to and from the eNodeB4 via the physical line (S1 line) of the E-UTRAN7.

The core network node device 3 is provided with the following elements whose functions are realized by a software module executed by the control unit 3a (or hardware logic operated by a command from the control unit 3a) (see also FIG. 1).
<Multicast participation management section 3b>
The following function implementation modules are included.
- Multicast participation accepting unit 3b1: Accepts a multicast group participation request from a UE (mobile terminal) 5 via an eNodeB (radio base station) 4. Specifically, a multicast group participation request from the UE5 is accepted together with the terminal address of the UE5.
- Multicast participation list registration unit 3b2: configured as a semiconductor memory or fixed storage device, stores and registers multicast group participation requests from each UE5 in the multicast participation list. Specifically, the multicast group participation request from UE5 is associated with the terminal address and registered in the multicast participation list.

- Registration deletion control unit 3b3: upon receiving a multicast group exit request from the UE (mobile terminal) 5, deletes the registration of the mobile terminal from the multicast participation list registration unit 3b2.
- Proxy registration request unit 3b4: request to the multicast router 8, which is an upper network device, to register the core network node device 3 as a multicast data distribution destination in the proxy list registration unit 8a provided in the multicast router 8 (proxy registration request) is sent to the upper-side transmitting/receiving section 3k. The proxy registration request is transmitted to the multicast router 8 when the core network node device 3 first receives the multicast group participation request from the UE 5. As will be described later, when the multicast router 8 is omitted, the proxy registration request section 3b4 is also omitted.

<Multicast proxy section 3c>
The following function implementation modules are included.
- Multicast data reception command section 3c1: Instructs the upper-side transceiver section 3k to receive multicast data distributed from the upper network (in this embodiment, the media server 6 and the multicast router 8). It cooperates with the upper-side transmitter/receiver 3k to realize the function of a multicast data receiver.
- Core side unicast bearer construction instruction transmission command unit 3c2: Sends a unicast bearer construction instruction to the eNodeB4 ( The core-side transmitting/receiving unit 3f is instructed to transmit to a wireless base station (radio base station). It cooperates with the core-side transmitter/receiver 3f to realize the function of a unicast bearer construction instruction transmitter. Specifically, the UE 5 to which the unicast bearer 12 is to be constructed is specified based on the terminal address in the multicast participation list, and an instruction to construct the unicast bearer 12 for the UE 5 is transmitted to the eNodeB 4 .

- Multicast data transfer command section 3c3: Instructs the core side transceiver section 3f to transfer multicast data to the eNodeB4 (wireless base station). It cooperates with the core-side transmitting/receiving section 3f to realize the function of a multicast data transfer section.
- Multicast data transmission stop command unit 3c4: Instructs the core-side transmitting/receiving unit 3f to stop distributing and transmitting multicast data to the UE5 whose registration has been deleted. It cooperates with the core-side transmitting/receiving section 3f to realize the function of a multicast data transmission stop control section.

- Distribution stop request command unit 3c5: As all registrations of UE5 are deleted from multicast participation list registration unit 3b2, sends a request to stop distribution of multicast data to multicast router 8 (upper network device) to upper-side transmitter/receiver 3k. issue the command to do so. It cooperates with the upper-side transmitting/receiving section 3k to realize the function of a distribution stop requesting section.

<UE connection management section 3d>
It allocates an IP address to the UE 5 connected (attached) to the core network node device 3 via the eNodeB 4 and manages the process of constructing an EPS bearer including the unicast bearer 12. The EPS bearer is a concept that combines the unicast bearer 12, which is a radio bearer between the UE5 and the eNodeB4, and a wired bearer on the core network side than the eNodeB4. The physical line on which the wired bearer is constructed is the physical line that forms the E-UTRAN 7 (specifically, the S1-MME line that connects the MME that forms the control plane side node with eNodeB4, and the user plane side node that forms the eNodeB4 side node). S1-U line that connects the S-GW (Serving Gateway) and the S5 that connects the P-GW (Packet data network Gateway) that forms the connection node between the S-GW (Serving Gateway) in the core network and the external network. It consists of a line. An EPS bearer is generated for each UE5 attached to the core network, and each bearer ID is assigned. Furthermore, in the attach sequence of the UE5, a unique IP address is given to each UE5 in addition to the bearer ID. Then, the bearer ID and IP address of each UE5 are stored in the UE address/bearer list storage unit 3d in a mutually correlated manner.

FIG. 3 is a block diagram showing an example of the configuration of the eNodeB4. The eNodeB 4 includes a control unit 4a configured with an MPU, an upper-side transmitting/receiving unit 4k for transmitting and receiving data between the core network node device 3 via the E-UTRAN 7, and a base station-side wireless transmitting/receiving unit 4f. has a hardware configuration that is connected to a bus. The eNodeB 4 is provided with the following elements whose functions are realized by software modules executed by the control unit 4a or hardware logic operated by instructions from the control unit 4a (see also FIG. 1).

- Unicast bearer construction instruction reception command section 4b: Instructs the upper-side transceiver section 4k to receive a unicast bearer construction instruction from the core network node device 3.
-Base station side unicast bearer construction instruction unit 4c: Upon receiving the unicast bearer construction instruction from the core network node device 3, the base station side wireless transmitting/receiving unit 4f is instructed to communicate with the UE5 (mobile terminal) registered in the multicast participation list. During this time, the construction of an individual unicast bearer 12 is commanded. It cooperates with the base station side radio transmitting/receiving unit 4f and the UE 5 to realize the function of the unicast bearer construction unit.
- Multicast data transmission command section 4d: Instructs the base station side wireless transmission/reception section 4f to transmit multicast data to the UE5 (mobile terminal) via the constructed unicast bearer 12. It cooperates with the base station side wireless transmitter/receiver 4f to realize the function of a multicast data transmitter.

FIG. 4 is a block diagram showing a configuration example of the UE5. The UE 5 has a hardware configuration in which a control unit 5a constituted by an MPU and a terminal-side wireless transmitting/receiving unit 5f are connected via a bus. Further, the following elements are provided whose functions are realized by software modules executed by the control unit 5a or hardware logic operated by instructions from the control unit 5a.
- Unicast bearer construction command section 5b: Receives a unicast bearer construction instruction from the eNodeB4, and instructs the terminal side wireless transmitting/receiving section 5f to construct a unicast bearer 12 with the eNodeB4. It cooperates with the terminal side wireless transmitting/receiving section 5f and the base station side wireless transmitting/receiving section 4f to realize the function of the unicast bearer construction section.
- Multicast participation request transmission command unit 5c: Instructs the terminal side wireless transmission/reception unit 5f to transmit a multicast participation request to the eNodeB4.

FIG. 5 is a schematic diagram showing an example of an IP packet distributed by multicast. The IP packet 300 consists of an IP header 301 and an IP payload 302, and in the IP header 301, a source IP address 301a and a destination IP address 301b of data to be written to the IP payload 302 are written. Further, in the IP payload 302, in the case of user data, data that is the main body of the distributed content is written, and in the case of control data, various control commands and the like are written. In the case of a multicast packet, a unique IP address for identifying the multicast group is written as the destination address 301b.

6 and 7 show the protocol stack of the radio interface in the LTE system, FIG. 6 shows the protocol stack of the user plane, and FIG. 7 shows the protocol stack of the control plane. The radio interface protocol is divided into layers 1 to 3 of the OSI reference model, and layer 1 is the PHY (physical) layer. Layer 2 includes a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, and a PDCP (Packet Data Convergence Protocol) layer. Layer 3 includes an RRC (Radio Resource Control) layer and a NAS (Non-Access Stratum) layer.

The role of each layer is as follows.
- PHY layer: Performs encoding/decoding, modulation/demodulation, antenna mapping/demapping, and resource mapping/demapping. Data and control signals are transmitted between the PHY layer of UE5 and the PHY layer of eNodeB4 via a physical channel.
- MAC layer: Performs data priority control, retransmission processing using HARQ (Hybrid ARQ), random access procedures, etc. Data and control signals are transmitted between the MAC layer of UE5 and the MAC layer of eNodeB4 via a transport channel. The MAC layer of the eNodeB4 includes a scheduler that determines uplink and downlink transport formats (transport block size, modulation and coding scheme (MCS)) and resource blocks to be allocated to the UE5.

- RLC layer: transmits data to the RLC layer on the receiving side using the functions of the MAC layer and PHY layer. Data and control signals are transmitted between the RLC layer of UE5 and the RLC layer of eNodeB4 via logical channels.
- PDCP layer: Performs header compression/expansion, encryption/decryption.
- RRC layer: Defined only in the control plane that handles control signals. Messages for various settings (RRC messages) are transmitted between the RRC layer of the UE 5 and the RRC layer of the eNodeB 4. The RRC layer controls logical channels, transport channels and physical channels according to the establishment, re-establishment and release of radio bearers (unicast bearers). If there is a connection (RRC connection) between the RRC of UE5 and the RRC of eNodeB4, UE5 is in RRC connected mode, otherwise it is in RRC idle mode.

The above layers are used in both the control plane and the user plane. On the other hand, only in the control plane, the UE 5 and the core network node device 3 are provided with a NAS layer that performs session management, mobility management, etc. above the RRC layer.

Next, FIG. 8 shows downlink channel mapping in the LTE system. Here, a mapping relationship between a logical channel (Downlink Logical Channel), a transport channel (Downlink Transport Channel), and a physical channel (Downlink Physical Channel) is shown. Below, they will be explained in order.
- DTCH (Dedicated Traffic Channel) is a dedicated logical channel for data transmission. DTCH is mapped to DLSCH (Downlink Shared Channel), which is a transport channel.
- DCCH (Dedicated Control Channel): A logical channel for transmitting individual control information between the UE 5 and the network. DCCH is used when UE5 has an RRC connection. DCCH is mapped to DLSCH.
- CCCH (Common Control Channel): A logical channel for transmission control information between the UE 5 and the eNodeB 4. CCCH is used when UE5 does not have an RRC connection with eNodeB4 (network). CCCH is mapped to DLSCH.

- BCCH (Broadcast Control Channel): A logical channel for distributing system information. The BCCH is mapped to a BCH (Broadcast Channel) or DLSCH, which is a transport channel.
- PCCH (Paging Control Channel): A logical channel for notifying paging information and system information changes. The PCCH is mapped to a PCH (Paging Channel), which is a transport channel.

- MCCH (Multicast Control Channel): A logical channel for multicast transmission. MCCH is used for transmitting MBMS control information for MTCH from eNodeB4 to UE5. MCCH is mapped to MCH (Multicast Channel), which is a transport channel.
- MTCH (Multicast Traffic Channel): A logical channel for transmitting multicast data (content) from the eNodeB4 to the UE5. MTCH is mapped to MCH.
In the present invention, by the function of the multicast proxy unit 3c of the core network node device 3 in FIG. It is important to note that these multicast channels (shown in dashed lines 50 in FIG. 8) are not used.

Further, the mapping relationship between transport channels and physical channels is as follows.
DLSCH and PCH: mapped to PDSCH (Physical Downlink Shared Channel). DLSCH supports HARQ, link adaptation, and dynamic resource allocation.
- BCH: Mapped to PBCH (Physical Broadcast Channel).
- MCH: Mapped to PMCH (Physical Multicast Channel). MCH supports MBSFN transmission by multiple cells, but is not used in the present invention.

Next, in the LTE system, the UE 5 wirelessly connects to the eNodeB 4 using OFDM (Orthogonal Frequency-Division Multiplexing) access (OFDMA). The OFDMA system is characterized as a two-dimensional multiple access system that combines frequency division multiplexing and time division multiplexing. Specifically, orthogonal channels (subcarriers) on the frequency axis and time axis are divided and allocated to the UE5, and subcarriers that are orthogonal on the frequency axis are divided so that the signal of each subcarrier becomes zero (0 point). To divide. By dividing subcarriers and allocating them on the frequency axis, even if one subcarrier is affected by fading, it is possible to select another subcarrier that is unaffected. This has the advantage that subcarriers can be used and wireless quality can be maintained.

In the OFDMA system, a resource block (hereinafter also referred to as RB) defined on a virtual plane extending between a frequency axis and a time axis is employed as a radio resource. As shown in FIG. 9, RB is defined as a block that divides the above plane into a matrix at 180 kHz/0.5 msec, and each block divides 12 adjacent subcarriers at 15 kHz intervals on the frequency axis and Contains one slot (7 symbols) of the frame. These RBs are assigned to the UE 5 as a set of two adjacent RBs (1 msec) on the time axis.

In the present invention, similarly to the conventional MBMS system, a UE 5 that has requested to participate in a multicast group is registered in the multicast group, and multicast data (content) is distributed to the registered UE 5. However, the core network node device 3 that manages the registration of the multicast group specifies the IP address of the registered UE 5, and uses that IP address to create an individual unicast bearer 12 between the UE 5 and the content distribution destination. The unicast bearer 12 is used to distribute multicast data.

In other words, it is sufficient to construct unicast bearers with a small frequency band occupation width and dynamic allocation control of frequency resources for the number of UE5s participating in the multicast group, regardless of the number of UE5s participating in the multicast group. Compared to the conventional MBMS system that uses multicast bearers that occupy a large frequency band, limited radio resources can be used more effectively. In addition, UE5 can receive multicast data even if it is a non-MBMS compatible device that cannot construct a multicast bearer (MBMS compatible devices can of course be used, but in a form where only the unicast part is used). ).

Furthermore, the UE5s that have finished distributing multicast data (content) exit the multicast group one by one, and the unicast bearers that have been set up are sequentially disconnected, so that the UE5s that have disbursed multicast data (content) exit from the multicast group. Each time, the occupied radio resources are released. Thereby, it is only necessary to allocate radio resources for establishing a unicast bearer to the UE5 that continues content distribution among the UE5s participating in the multicast group.

The operation of the multicast distribution system 1 shown in FIG. 1 will be explained below using communication flow diagrams shown in FIGS. 10 to 13. FIG. 10 shows the flow of processing when the UE 5 connects (attachs) to the LTE network upon power-on (start-up). In FIG. 10, as an example, a situation is shown in which two UE(I) and UE(II) sequentially connect to the eNodeB4. That is, in TS901, the power of UE (I) is turned on. Along with this, an attach sequence for initial connection is executed between the UE (I), the eNodeB 4, and the core network node device 3. This attach sequence is performed using the same procedure as normal unicast communication in the LTE system.

When the above attach sequence is completed, an EPS bearer (I) is constructed between the UE (I), the eNodeB 4, and the core network node device 3 in the TS 902. At this time, an IP address (11.11.15.105) is assigned to the UE (I), and BID#1 is assigned as a bearer ID to the constructed EPS bearer (I), and these are associated with each other in TS903. and stored in the UE address/bearer list storage section 3d1.

Subsequently, in TS904, the power of the UE (II) is turned on. Along with this, an attach sequence for initial connection is executed between the UE (II), the eNodeB 4, and the core network node device 3. Then, in TS905, an EPS bearer (II) is constructed between the UE (II), the eNodeB 4, and the core network node device 3. At this time, an IP address (11.11.15.106) is allocated to the UE (II), and BID#2 is allocated as a bearer ID to the constructed EPS bearer (II), and these are associated with each other in TS906. and is additionally stored in the UE address/bearer list storage section 3d1. Thereafter, even when a new UE 5 is connected, the same process is repeated.

FIG. 11 shows the flow of processing when each UE 5 requests to participate in a multicast group. There is a radio bearer connection between the eNodeB4 and each UE5 (UE(I), UE(II),...), and a wired bearer connection using S1 and S5 lines between the eNodeB4 and the core network node device 3. . As described above, the IP addresses of UE (I) and UE (II) are "11.11.15.105" and "11.11.15.106", respectively. Furthermore, the group IP address of the multicast group is "239.255.0.1". On the other hand, the IP address "224.0.0.22" shown in association with the multicast router 8 is a link local address uniquely allocated to IGMPv3. The destination specified by this IP address is all the host node devices within the local network area to which the multicast router 8 belongs, and a control message for joining/leaving the multicast group is transmitted using an IP packet indicating the destination. As a result, by receiving this, the multicast router 8 plays the role of managing participation and withdrawal from the group.

In the state before the start of the multicast stream, the multicast participation list registration unit 3b2 of the core network node device 3 is in an empty state in which neither the IP address of the multicast group nor the IP address of the participating UE is registered (TS1001 ). Then, in the TS 1002, a multicast group participation request is sent from the UE (I) to the core network node device 3 via the eNodeB 4, specifying the group IP address "239.255.0.1." Note that the same applies below, but below the arrow indicating the data transmission direction, the source address and destination address written in the IP header of the transmitted packet are displayed (for example, in TS1002, the "transmission" From: 11.11.15.105, To 224.0.0.22”).

The core network node device 3 receives this, and the TS 1003 sends the group IP address ("239.255.0.1") and the IP address of the participating UE (here, "11.11.15.105" of UE (I)) to the multicast participation list registration section 3b2. ) is registered. Furthermore, since this is the first multicast group participation request in the core network node device 3, the multicast group participation request is transmitted to the multicast router 8, which is the upper network device, in TS1004. In the multicast router 8, the group IP address ("239.255.0.1") and the IP address for specifying the core network node device 3 (here, the first multicast group for the core network node device 3) are stored in the proxy list registration section 8a. The IP address "11.11.15.105" of the UE (I) that sent the participation request is registered (proxy list registration).

Subsequently, in TS1006, a multicast group participation request is similarly transmitted from the UE (II) to the core network node device 3 via the eNodeB4. The core network node device 3 receives this, and in TS1007, the IP address "11.11.15.106" of the UE (II) is additionally registered in the multicast participation list registration unit 3b2. Here, since the proxy list registration to the multicast router 8 has already been completed in TS 1004, information transmission for new registration is not performed. Hereinafter, if there are more UE5s participating in the multicast group, the procedures of TS1006 and TS1007 are repeated, and the IP address of each UE5 is sequentially registered in the multicast participation list registration section 3b2.

When the registration process of each UE5's multicast group participation request to the multicast participation list registration unit 3b2 is completed, the process moves to the content distribution process sequence shown in FIG. 12. The multicast router 8 receives content stream data (multicast data) from the media server 6, and transmits it to the core network node device 3 registered in the proxy list registration unit 8a (FIG. 2) (TS2001). The multicast router 8 transfers the stream data to the core network node device 3 registered as a proxy in the proxy list registration section 8a (if there are multiple core network node devices 3 registered as a proxy, each core network node device 3 (distributes and transfers stream data to).

At this time, the content of the IP header of the stream data packet sent from the media server 6 to the core network node device 3 via the multicast router 8 is "Source: 192.168.12.4 (media server), destination 239.255.0.1 ( multicast group). As the destination address is highlighted with an underline, this is not a unicast packet destined for a specific UE5, but a multicast packet targeted for transmission to the UE5 that has joined the multicast group indicated by the IP address. It means that.

In the conventional MBMS system, the multicast packet is distributed from the core network node device 3 via the eNodeB to each UE using a multicast bearer dedicated to MBMS. In normal MBMS standards, the transport channel on which multicast bearers are constructed is a dedicated MCH, as described above, and in order to secure the transmission capacity for one-to-many communication dedicated to the downlink, the communication channel is fixed and has a fixed bandwidth. is also widely secured (for example, 20 to 80 MHz). On the other hand, in FIG. 12, the unicast bearer 12 (or EPS bearer) is extended from the core network node device 3 to each UE 5. According to the 3GPP protocol, the only data packets that can be sent on a unicast bearer are unicast packets in which the IP address of the destination UE is written as the destination IP address, and the destination IP address is a group address. The multicast packet that is 1 is discarded by the core network node device 3, and normally does not flow on the unicast bearer 12.

However, in the multicast distribution system 1 shown in FIG. 12, the function of the multicast proxy section 3c incorporated in the core network node device 3 identifies the destination UE5 based on the IP address registered in the multicast participation list registration section 3b2. When the content distribution time arrives and multicast data is sent from the upper network (multicast router 8), a unicast bearer 1 (EPS bearer) specialized for multicast data distribution is established between the destination UE 5 and the multicast data. are constructed separately. The multicast proxy unit 3c checks the content of the destination address in the IP header of the received stream data packet, and if the destination address is the IP address of the multicast group in which those UE5s participate, the multicast proxy unit 3c determines the destination address. To distribute and transfer to each UE 5 connected to a unicast bearer 12 without changing the address. In other words, the stream data flows on the unicast bearer 12 in the format of the multicast data packet. This allows the core network node device 3 to distribute multicast data without adding or rewriting TEIDs, etc., which were conventionally necessary for tunneling multicast packets, thereby reducing the processing load.

Specifically, in FIG. 12, the core network node device 3 refers to the multicast participation list registration unit 3b2 in TS2003 and TS2004, and determines the IP address of the UE5 to which the multicast data should be distributed based on the received multicast IP address. List. Based on the listed IP address of the UE 5, the core network node device 3 refers to the storage contents of the UE address/bearer list storage section 3d1, identifies the bearer ID to which the multicast data should be distributed, and selects the bearer ID. Stream data (multicast data packets) is distributed and transferred to each UE5 (UE(I), UE(II), . . . ) via the EPS bearer (and eNodeB4) indicated by .

As long as the UE 5 is equipped with a wireless interface capable of constructing a unicast bearer, it is possible to receive multicast content distribution even if the UE 5 is not particularly compatible with MBMS. In a 3GPP specification wireless communication network, there is no need to reserve radio resource blocks in advance for each unicast bearer 12, and each unicast bearer 12 is dynamically allocated only when distribution data exists, and the optimal modulation degree is assigned to each UE 5. It is selected and data is transmitted. By using this method for multicast data distribution, the method of the present invention can greatly contribute to more effective use of radio resources than a general method that uses multicast bearers. Especially when the number of UE5s participating in multicast is small, this effect becomes more remarkable.

FIG. 13 shows the flow of processing in which the UE5s that have finished streaming sequentially exit the multicast group and end the content distribution. In TS2001 to TS2006, the stream data described using FIG. 12 is being distributed to each UE5. Next, in TS3001, the distribution of the content stream data is completed at UE (I) ("11.11.15.105"), and the multicast group exit request from UE (I) specifies the group IP address "239.255.0.1". It is transmitted to the core network node device 3 via the eNodeB 4 in the form of: The core network node device 3 receives this and deletes the IP address ("11.11.15.105") of the UE (I) from the multicast participation list registration section 3b2 in the TS 3002.

At this time, the eNodeB4 notifies the UE (I) that has left the group of the end of the unicast bearer (EPS bearer) construction session. In response to this, UE (I) disconnects the wireless connection state. The eNodeB4 releases the radio resources allocated to constructing the unicast bearer (EPS bearer). On the other hand, stream data distribution (TS2001', 2002', 2004', 2006') to UE (II) "11.11.15.106" continues.

Subsequently, in TS3003, the distribution of the content stream data is completed at UE (II) ("11.11.15.106"), and the multicast group exit request from UE (II) specifies the group IP address "239.255.0.1". It is transmitted to the core network node device 3 via the eNodeB 4. The core network node device 3 receives this and deletes the IP address ("11.11.15.106") of the UE (II) from the multicast participation list registration section 3b2 in the TS3004. As a result, the wireless connection with UE (II) is also disconnected, and the wireless resources allocated for EPS bearer construction are released. These processes are repeated until streaming to all UE5 is completed.

Then, for example, in TS3004, when all the registrations of UE5 (IP address) in the multicast participation list registration section 3b2 are deleted, the process proceeds to TS3005, and the core network node device 3 sends the group IP address "239.255.0.1" to the multicast router 8. ” to request to leave the multicast group. In response to this, the multicast router 8 receives the IP address for identifying the core network device 3 (of the UE (I) that sent the first multicast group participation request to the core network node device 3) from the proxy list registration unit 8a in TS3006. Delete the IP address "11.11.15.105" and stop streaming data.

In this way, the unicast bearer 12 (EPS bearer) established between UE5 and eNodeB4 for multicast data distribution is disconnected each time UE5 leaves the multicast group, and the radio resources occupied each time are released. be done. Therefore, the usage status of wireless resources can be optimized at any time according to the communication status of multicast distribution, which can contribute to the effective use of limited wireless resources.

Although the embodiments of the present invention have been described above, they are merely examples, and the present invention is not limited thereto. For example, in FIG. 1, if there is only one core network node device 3 to which multicast stream data is delivered from the media server 6, the multicast router 8 can be omitted, so the core network node device 3 in FIGS. The flow of proxy registration processing between the node device 3 and the multicast router 8 becomes unnecessary.

1 Multicast distribution system 3 Core network node device 3a Control unit (MPU)
3b Multicast participation management section 3b1 Multicast participation reception section 3b2 Multicast participation list registration section 3b3 Registration deletion control section 3b4 Proxy registration request section 3c Multicast proxy section 3c1 Multicast data reception command section 3c2 Core side unicast bearer construction instruction transmission command section 3c3 Multicast data Transfer command unit 3c4 Multicast data transmission stop command unit 3c5 Distribution stop request command unit 3f Core side transmitter/receiver 3k Upper side transmitter/receiver 4 eNodeB (wireless base station)
4a Control unit (MPU)
4b Unicast bearer construction instruction reception command section 4c Base station side unicast bearer construction instruction section 4d Multicast data transmission command section 4f Base station side wireless transmission/reception section 4k Upper side transmission/reception section 5 UE (mobile terminal)
5a Control unit (MPU)
5b Unicast bearer construction command section 5c Multicast participation request transmission command section 5f Terminal side wireless transmission/reception section 6 Media server 7 E-UTRAN
12 Unicast bearer

Claims (5)

It has a core network node device, a wireless base station connected to the core network node device by a physical line, and a mobile terminal wirelessly connected to the wireless base station, and transmits MBMS from the core network node device to the mobile terminal. (Multimedia Broadcast Multicast Service) compliant multicast data.
The core network node device includes:
a multicast participation reception unit that receives a multicast group participation request from the mobile terminal by receiving a group IP address of the multicast group from the mobile terminal via the wireless base station;
a multicast participation list registration unit that registers the multicast group participation request in a multicast participation list;
A multicast data receiving unit that receives multicast data distributed from an upper network sends a unicast bearer construction instruction to construct an individual unicast bearer with the mobile terminal registered in the multicast participation list to the radio. A multicast proxy unit having a unicast bearer construction instruction transmission unit that transmits toward a base station, and a multicast data transfer unit that transfers the multicast data to the wireless base station,
The wireless base station includes:
Build an individual unicast bearer between the unicast bearer construction instruction receiving unit that receives the unicast bearer construction instruction and the mobile terminal that has received the unicast bearer construction instruction and is registered in the multicast participation list. a unicast bearer construction unit that transmits the multicast data to the mobile terminal via the unicast bearer;
The multicast data is distributed and transmitted from the core network node device via the radio base station to the mobile terminals registered in the multicast participation list via the individual unicast bearers. Multicast distribution system. In the core network node device,
The multicast participation reception unit receives a multicast group participation request from the mobile terminal together with the terminal address of the mobile terminal,
The multicast participation list registration unit registers the multicast group participation request from the mobile terminal in the multicast participation list in association with the terminal address,
The unicast bearer construction instruction transmitting unit of the multicast proxy unit identifies the mobile terminal to which the unicast bearer is to be constructed based on the terminal address in the multicast participation list, and assigns the unicast bearer to the mobile terminal. 2. The multicast distribution system according to claim 1, wherein the multicast distribution system transmits a construction instruction to the wireless base station. The multicast proxy unit transfers the multicast data in which a multicast address is stored as a destination address in a header portion of a packet to the wireless base station without changing the destination address,
3. The multicast distribution system according to claim 2, wherein the multicast data transmitter of the wireless base station transmits the multicast data to the mobile terminal via the unicast bearer without changing the destination address. The core network node device includes a registration deletion control unit that deletes the registration of the mobile terminal from the multicast participation list upon receiving a multicast group exit request from the mobile terminal, and a registration deletion control unit that deletes the registration of the mobile terminal from the multicast participation list; a multicast data transmission stop control unit that stops distribution and transmission of the multicast data; and a distribution that requests the upper network to stop distribution of the multicast data when all registrations of the mobile terminals are deleted from the multicast participation list. and a stop request section,
The unicast bearer construction unit of the radio base station releases the construction state of the unicast bearer that has been established with the mobile terminal as the mobile terminal is deleted from the multicast participation list registration unit. The multicast distribution system according to claim 3. a multicast participation reception unit that accepts a multicast group participation request from a mobile terminal by receiving a group IP address of the multicast group from the mobile terminal via a wireless base station ;
a multicast participation list registration unit that registers the multicast group participation request in a multicast participation list;
A multicast data receiving unit that receives multicast data distributed from an upper network sends a unicast bearer construction instruction to construct an individual unicast bearer with the mobile terminal registered in the multicast participation list to the radio. a multicast proxy unit including a unicast bearer construction instruction transmission unit that transmits to a base station, and a multicast data transfer unit that transfers the multicast data to the wireless base station;
A core network node device comprising:

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