JP2020123942A - Multicast distribution system - Google Patents

Abstract

To provide a multicast distribution system capable of reducing the number of control devices in a core network and greatly simplifying a processing procedure for establishing a multicast bearer.SOLUTION: A multicast proxy unit 3b is installed in a core network control node device 3 to receive multicast data, and the ability to handle multicast user plane signals is added. Then, a multicast bearer construction instruction is sent from the core network control node device 3 to a wireless base station 4 as an initial configuration instruction along with a unicast bearer construction instruction. The wireless base station 4 sends those multicast bearer construction instructions and unicast bearer construction instructions to a mobile terminal 5 when the mobile terminal 5 initially connects. The mobile terminal 5 receives this and builds a multicast bearer and a unicast bearer with the wireless base station 4 at an initial connection stage to the wireless base station 4.SELECTED DRAWING: Figure 1

Description

The present invention relates to a multicast distribution system including a mobile terminal such as a mobile terminal, and more particularly, in an LTE (Long Term Evolution) system or the like, a multicast data distribution function conforming to eMBMS (evolved Multimedia Broadcast Multicast Service) is further provided. The present invention relates to a multicast distribution system for realizing a simple network configuration.

In 3GPP (Third Generation Partnership Project), which is a standardization project for mobile communication systems, eMBMS is specified to provide a multicast/broadcast service. In the current eMBMS, multicast/broadcast data is transmitted via a PMCH (Physical Multicast Channel) for each MBSFN (Multicast-Broadcast Single-Frequency Network) area unit including a plurality of cells (MBSFN transmission).

These techniques are known from Patent Document 1, Patent Document 2, and the like. For example, in paragraphs 0067 and below of Patent Document 2, a system for delivering eMBMS data from a core network by IP multicast is disclosed as follows, for example. That is, the core network notifies the wireless base station of the IP multicast address when establishing the session. The wireless base station joins the IP multicast group indicated by the IP multicast address. Packets of eMBMS data are distributed to the wireless base stations that have joined the IP multicast group by the IP multicast router in the IP network. In this case, since eMBMS data is distributed by IP multicast, it is necessary to provide an IP multicast router in the IP network.

Although the details of the IP multicast router are not mentioned in Patent Document 1, the specific disclosure is disclosed in paragraph 0037 and the following paragraphs of Patent Document 2. The summary will be described below with reference to FIG. A core network (EPC: Evolved Packet Core) includes a BM-SC (Broadcast Multicast Service Center) 206, an MBMS-GW (Multimedia Broadcast Multicast Service Gateway) 201, an MME (Mobility Management Entity) 202, and an MCE (Multi-cell multicast Coordination Entity). ) 203 is included. The MBMS-GW 201 is connected to the eNodeB (radio base station) 204 via the M1 interface, connected to the MME 202 via the Sm interface, and further connected to the BM-SC 206 via the SG-mb and SGi-mb interfaces. ..

The BM-SC 206 collects multicast content data from the media server 207 that is a data delivery source, manages group membership and QoS (Quality of Service) that is a delivery destination, announces multicast/broadcast sessions, and delivers multicasts such as security. Perform general service management. The MBMS-GW 201 corresponds to a gateway on the user plane (U-Plane) side of the core network in eMBMS, and performs multicast data transmission and session control for the eNodeB 204. On the other hand, the MME 202 also corresponds to a gateway on the control plane (C-Plane) side, and functions as an exchange that mediates control signals necessary for communication with the eNodeB 204 that is a base station. Specifically, for UE authentication control called NAS (Non Access Stratum), routing (connection path setting) request, and for exchanging data transmission/reception management information for each UE between different eNodeBs at the time of handover. Mediate. The MCE 203 corresponds to a multicast control device, and has functions such as radio resource management and allocation of MBSFN, and designates radio resources to be used for data transmission between eNodeBs forming the MBSFN, so that eNodeB 204 can serve as a mobile terminal. It is responsible for synchronizing the content distribution of.

The M1 interface is a user plane interface and functions as a transmission path for user data in multicast. On the other hand, the M2 interface and the M3 interface are control plane interfaces and function as control data transmission paths in multicast. Specifically, the M2 interface constitutes a control plane interface in the E-UTRAN, and the M3 interface constitutes a control plane interface between the E-UTRAN and the core network. The SGmb/SGimb interface is a shared interface of the control plane and the user plane between the BM-SC 206 and the MBMS-GW 201 in the core network. Further, the SM interface is for forming a reference point of the control plane between the MME 202 and the MBMS-GW 201.

JP, 2013-146109, A JP, 2018-113706, A

The above-mentioned conventional system configuration is constructed assuming a situation in which, for example, a large amount of moving image data and the like are simultaneously stream-distributed to an unspecified large number of UEs on the IP network. For example, the content data distributed by multicast is transmitted to the core network after passing through the BM-SC 206 for the purpose of collection and distribution management. Then, in order to realize large-capacity content processing, the multicast data forming the content is received by the MBMS-GW 201 which is the gateway device on the user plane side. On the other hand, the control data is generated by the MME 202, which is the gateway device on the control plane side, by referring to the MBMS-GW 201 via the SM interface. The control data flows to the eNodeB 204 while being separated from the user data via a transmission path (M3/M2 interface) different from the user plane. That is, in the above-described conventional configuration, at least three devices, BM-SC 206, MME 202, and MBMS-GW 201, are required as devices for multicast data distribution processing at the entrance of the core network. Further, the MCE 203, which is responsible for synchronization control of content distribution between mobile terminals, is further required as a device on the control plane side.

As described above, if the number of control devices on the core network side increases, naturally the operation sequence must be complicated. FIG. 14 shows a flow of the operation by a communication sequence diagram. When the eNodeB 204 is started up, the initialization process on the control plane side causes the eNodeB 204 to be an activated base station in the MCE 203 and the MME 202 which are upper devices. In order to be recognized, it is necessary to sequentially perform a setup request and response procedure (reference numeral 161) via the M2 interface and the M3 interface. Further, the procedure of request/response to start a session from the BM-SC 206 side to the eNodeB 204 to build a multicast bearer that is a signal transmission path for wirelessly transmitting multicast data is also between BM-SC 206/MBMS-GW 201, between MBMS-GW 201/MME 202, and It is absolutely necessary between the MME 202/MCE 203, between the MCE 203/eNodeB 204, and between adjacent control devices (reference numerals 162 and 163). Further, between the MCE 203 and the eNodeB 204, the step of transmitting/responding the MBMS scheduling information for the above-mentioned synchronization control is also executed.

For example, for small-scale networks with limited areas, such as disaster response notifications and regional revitalization, want to multicast videos such as relatively small data sizes to a relatively small number of mobile terminals in the area. Is also expected to increase in the future. However, in the above-described conventional system configuration, the number of control devices is large, the hardware configuration is inevitably complicated and expensive, and the number of data transmission steps is large as shown in FIG. Therefore, it is clearly unsuitable for multicast distribution in small networks.

An object of the present invention is to provide a multicast distribution system that can reduce the number of control devices in a core network and can also greatly simplify the processing procedure for establishing a multicast bearer.

In order to solve the above-mentioned problems, a multicast distribution system of the present invention includes a core network control node device, a wireless base station connected to the core network control node device by a physical line, and a wireless connection to the wireless base station. And a mobile terminal which is configured to deliver multicast data conforming to eMBMS (evolved Multimedia Broadcast Multicast Service) from the core network control node device to the mobile terminal. The core network control node device is a control plane of the core network and a user. It is also used as a control node of the plane, and sends and receives the core side transceiver, the multicast proxy unit that causes the core side transceiver to receive the multicast data distributed from the outside, and the multicast bearer construction instruction at the initial connection of the mobile terminal. Core side multicast bearer construction instruction unit to be transmitted to the core side transceiver unit for the radio base station, and core side unicast to be transmitted to the core side transceiver unit for the unicast bearer construction instruction at the initial connection of the mobile terminal The radio base station comprises a bearer construction instruction unit, a multicast bearer construction instruction reception unit that receives a multicast bearer construction instruction, a unicast bearer construction instruction reception unit that receives a unicast bearer construction instruction, and radio transmission/reception on the base station side. And a base station side wireless bearer construction instruction unit for sending a multicast bearer construction instruction to the mobile terminal, and a base station side wireless transceiver unit for sending a unicast bearer construction instruction to the mobile terminal. The base station-side unicast bearer establishment instruction unit is provided, and the mobile terminal receives the terminal-side wireless transmission/reception unit and the multicast bearer establishment instruction so that the terminal establishes a multicast bearer with the radio base station at the initial connection stage. Unicast to be built in the terminal side wireless transceiver at the initial connection stage by receiving the multicast bearer construction unit to be constructed in the side wireless transceiver and the unicast bearer construction instruction at the initial connection stage A bearer construction unit is provided, and the multicast data is transmitted to the mobile terminal via the core network control node device, the radio base station and the multicast bearer.

In the multicast distribution system of the present invention, the core network control node device is configured as a device that is also used as a control node of the control plane and the user plane, and a multicast proxy unit for receiving multicast data is provided in the core network control node device. Set up. That is, the core network control node device is configured to have a function of handling multicast user plane data. Then, the multicast bearer establishment instruction is transmitted together with the unicast bearer establishment instruction as an initialization instruction from the core network control node device to the radio base station (e.g., eNodeB). The radio base station transmits the multicast bearer construction instruction and the unicast bearer construction instruction to the mobile terminal when the mobile terminal initially connects, and the mobile terminal receives the multicast bearer construction instruction with the radio base station. A unicast bearer is constructed at the initial connection stage to the radio base station.

That is, the core network control node device is provided with a multicast proxy unit and functions as a gateway that collectively handles data of both the control plane and the user plane, and thus is provided exclusively for processing on the user plane side in the conventional system. The old MBMS-GW is no longer needed. In addition, the multicast proxy unit is responsible for collecting the multicast data data (for example, content data) from the media server, and a multicast bearer is set up by default with the wireless base station, so that a substantial BM-SC is provided. The core network control node device can also substitute the function of. Therefore, according to the configuration of the present invention, the BM-SC can be omitted.

As a result, the hardware configuration of the entire system and the operation sequence (software for achieving the operation) for realizing the multicast distribution are significantly simplified, and the number of steps of the multicast bearer establishment setting process can be significantly reduced. .. Also, by unifying the control plane side and user plane side processing devices into a core network control node device, synchronization control of control data and user data becomes easy, and an extra device such as MCE can be installed. There is no need to provide it. Furthermore, when the mobile terminal initially connects to the wireless base station, a state in which not only a unicast bearer but also a multicast bearer is set up by default between the mobile terminal and the core network, so that multicast data is transmitted to the mobile terminal. The environment that can be sent to the system will be set immediately after the system is started up, and delays in distribution will be less likely to occur. By simplifying the device and software, it becomes possible to flexibly meet the demand for multicast distribution to a relatively small number of mobile terminals in a small area limited network.

FIG. 1 is a block diagram of a multicast distribution system that is an embodiment of the present invention. FIG. 3 is a block diagram of an EPC (core network control node device). The block diagram of eNodeB (radio|wireless base station) and UE (mobile terminal). A conceptual diagram of an IP packet. The figure which shows notionally the protocol stack of the control plane of 3GPP. The figure which shows notionally the protocol stack of the user plane of 3GPP. The figure which shows notionally the channel mapping of the downlink in this invention. Resource block conceptual diagram. The figure which shows the concept of the wireless data frame with which the MIB was delivered delivered using PBCH. The communication flow figure which shows the session sequence at the time of constructing a default multicast bearer in the multicast distribution system of this invention. 6 is a flowchart showing the flow of processing on the EPC side. The flowchart which shows the flow of a process by the side of UE. The block diagram of the conventional multicast distribution system. The communication flow figure which shows the session sequence at the time of constructing a multicast bearer in the conventional multicast delivery system.

Hereinafter, embodiments for carrying out the present invention will be described with reference to 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 conforming to the 3GPP (Third Generation Partnership Project) specifications, specifically, an LTE system. The main part of the network is a core network control node device (hereinafter referred to as EPC (Evolved Packet Core)) 3, an eNodeB 4 forming a radio base station, and an E-UTRAN 7 (Evolved Universal Terrestrial) forming a physical line network connecting these. Radio Access Network: The part shown is called S1 line), and a plurality of UEs 5 (User Equipment: mobile terminals) are wirelessly connected to the eNodeB 4. Although not shown, the E-UTRAN7 includes an X2 line for handover for connecting the eNodeB4 to another eNodeB4.

The EPC 3 is configured to have both the functions of the control node device of the control plane and the control node device of the user plane. Among these, the node device function on the control plane side has a function equivalent to that of the MME (Mobility Management Entity) 202 in FIG. 14, while the node device function on the user plane side handles only multicast data. Instead of the 14 MBMS-GW 201, a PGW (Packet Data Gate Way) function is incorporated. The PGW is responsible for unicast user data packet distribution control. However, as will be described later, in the present invention, the multicast proxy unit 3b is functionally incorporated in the EPC 3 so that the multicast user data packet It is configured such that distribution control can be performed (needless to say, transmission/reception of unicast data is also possible with the UE 5 via the eNodeB 4). The eNodeB 4 is connected to the EPC 3 via the E-UTRAN 7. Then, the EPC 3 receives the multicast data forming the distribution content from the media server 6 by the multicast proxy unit 3b, and distributes the multicast data conforming to the eMBMS (evolved Multimedia Broadcast Multicast Service) from the EPC 3 to the UE 5 via the eNodeB 4. It is supposed to be done.

FIG. 2 is a block diagram showing a configuration example of the EPC 3. The EPC 3 is a hardware in which a control unit 3a configured by an MPU (Micro Processor Unit), an upper-side transmission/reception unit 3k for receiving multicast data from the media server 6, and a core-side transmission/reception unit 3f are bus-connected. Have a configuration. The core side transmitting/receiving unit 3f is for transmitting/receiving unicast data and multicast data to/from the eNodeB 4.

The EPC 3 is provided with the following elements whose functions are realized by a software module executed by the control unit 3a (or a hardware logic operated by a command from the control unit 3a).
Multicast proxy unit 3b: The higher-order side transmitting/receiving unit 3k receives multicast data distributed from the outside.
-Core-side multicast bearer setting instruction unit 3d: Causes the core-side transceiver unit 3f to transmit a multicast bearer establishment instruction at the time of initial connection of the UE 5 to the eNodeB 4.
Core-side unicast bearer setting instruction unit 3e: Sends a unicast bearer establishment instruction at the time of initial connection of the UE 5 to the core-side transceiver unit 3f toward the eNodeB 4.
Multicast packet management unit 3j: Determines whether the delivered data is a unicast packet or a multicast packet based on the contents of the destination IP address 301b of the IP packet 300 shown in FIG. If there is, it is determined whether or not the packet is a previously registered multicast packet to be distributed.

FIG. 3 is a block diagram showing a configuration example of the eNodeB 4 and the UE 5. The eNodeB 4 is a control unit 4a configured by an MPU, and an upper-side transmission/reception unit 4k for transmitting/receiving unicast data and multicast data between the EPC 3 and the E-UTRAN 7, and a base station-side wireless transmission/reception unit 4f. And have a hardware configuration in which they are connected to the bus. The base station side wireless transmission/reception unit 4f includes a unicast transmission/reception I/F 4g for transmitting/receiving unicast data and a multicast transmission/reception I/F 4h for transmitting/receiving multicast data. The upper-side transmitting/receiving unit 4k functions as a multicast bearer construction instruction receiving unit that receives a multicast bearer construction instruction from the EPC 3 and a multicast bearer construction instruction receiving unit that also receives a unicast bearer construction instruction.

Further, the eNodeB 4 is provided with the following elements that realize functions by a software module executed by the control unit 4a or a hardware logic that operates according to a command from the control unit 4a.
Base station side multicast bearer setting instruction unit 4d: Causes the UE 5 to transmit a multicast bearer establishment instruction to the base station side wireless transmission/reception unit 4f upon initial connection with the UE5.
Base station side unicast bearer setting instruction unit 4e: Causes the UE5 to transmit a unicast bearer establishment instruction to the base station side wireless transmission/reception unit 4f upon initial connection with the UE5.
-Multicast channel information distribution unit: PBCH (Physical Broadcast Channel: physical broadcast channel) is provided to the UE 5 prior to the establishment of the multicast bearer between the UE 5 and the multicast channel information that is information necessary for setting the channel of the multicast bearer. ) Is used for delivery.

Also, the UE 5 has a hardware configuration in which a control unit 5a configured by an MPU and a terminal-side wireless transmission/reception unit 5f are bus-connected. The terminal side wireless transmission/reception unit 5f includes a unicast transmission/reception I/F 5g for receiving unicast data and a multicast transmission/reception I/F 5h for receiving multicast data. In addition, the following elements that realize functions by a software module executed by the control unit 4a or a hardware logic that operates according to a command from the control unit 5a are provided.
-Multicast bearer construction unit 5b: By receiving a multicast bearer construction instruction from the eNodeB 4, the multicast bearer 11 is connected to the eNodeB 4 at the initial connection stage to the terminal side wireless transmission/reception unit 5f with a PMCH (Physical Multicast Channel: physical multicast channel). ) Is used for construction.
-Unicast bearer construction unit 5c: PDSCH (Physical Multicast Downlink Multicast Shared) for the terminal side wireless transmission/reception unit 5f at the initial connection stage of the unicast bearer 12 with the eNodeB4 by receiving the unicast bearer construction instruction from the eNodeB4. Channel: Physical downlink shared channel).
Multicast channel setting unit 5i: receives the multicast channel information and sets the channel of the multicast bearer 11.

FIG. 4 is a schematic diagram showing an example of an IP packet delivered by unicast or multicast. The IP packet 300 includes an IP header 301 and an IP payload 302, and a packet identification number, a data delivery source IP address, a data delivery destination IP address, and the like are written in the IP header 301. Further, in the IP payload 302, data that is the main body of the distribution content is written in the case of user data, and various control commands and the like are written in the case of control data. In the case of a unicast packet, the IP address of the destination UE 5 is written as the data delivery destination IP address. On the other hand, in the case of a multicast packet, a unique IP address indicating the delivery destination of the multicast packet is written.

5 and 6 show a protocol stack of a radio interface in the LTE system, FIG. 5 shows a protocol stack of a user plane, and FIG. 6 shows a protocol stack of a 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. The 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: non-access) 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 via the physical channel between the PHY layer of the UE 5 and the PHY layer of the eNodeB 4.
MAC layer: Performs priority control of data, retransmission processing by HARQ (Hybrid ARQ), random access procedure, and the like. Data and control signals are transmitted between the MAC layer of the UE 5 and the MAC layer of the eNodeB 4 via the transport channel. The MAC layer of the eNodeB 4 includes a scheduler that determines a transport format (transport block size, modulation/coding method (MCS)) of uplink and downlink and a resource block allocated to the UE 5.

RLC layer: Data is transmitted to the RLC layer on the receiving side by utilizing the functions of the MAC layer and the PHY layer. Data and control signals are transmitted via a logical channel between the RLC layer of the UE 5 and the RLC layer of the eNodeB 4.
-PDCP layer: Performs header compression/decompression and 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 establishment, re-establishment and release of radio bearers (multicast bearers and unicast bearers). When there is a connection (RRC connection) between the RRC of the UE 5 and the RRC of the eNodeB 4, the UE 5 enters the RRC connected mode, and otherwise the RRC idle mode.

The above layers are used both in the control plane and the user plane. On the other hand, only in the control plane, the UE 5 and the EPC 3 are provided with a NAS layer for performing session management, mobility management, and the like, which is higher than the RRC layer.

Next, FIG. 7 shows downlink channel mapping in the LTE system. Here, the mapping relationship among logical channels (Downlink Logical Channel), transport channels (Downlink Transport Channel), and physical channels (Downlink Physical Channel) is shown. Hereinafter, they will be described in order.
DTCH (Dedicated Traffic Channel) is a dedicated logical channel for data transmission. The DTCH is mapped to DLSCH (Downlink Shared Channel) which is a transport channel.
DCCH (Dedicated Control Channel): a logical channel for transmitting dedicated 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. The CCCH is used when the UE 5 does not have an RRC connection with the eNodeB 4 (network). CCCH is mapped to DL-SCH.

-BCCH (Broadcast Control Channel): A logical channel for system information distribution. BCCH is mapped to BCH (Broadcast Channel) or DLSCH which is a transport channel.
PCCH (Paging Control Channel): A logical channel for notifying the change of paging information and system information. PCCH is mapped to PCH (Paging Channel) which is a transport channel.
MCCH (Multicast Control Channel): A logical channel for multicast transmission. The MCCH is used for transmitting eMBMS control information for MTCH from the eNodeB 4 to the UE 5. The 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 eNodeB 4 to the UE 5. MTCH is mapped to MCH.

The mapping relationship between transport channels and physical channels is as follows.
DLSCH and PCH: Mapped to PDSCH (Physical Downlink Shared Channel). DL-SCH supports HARQ, link adaptation, and dynamic resource allocation.
BCH: Mapped to PBCH (Physical Broadcast Channel).
MCH: Mapped to PMCH (Physical Multicast Channel). The MCH supports MBSFN transmission by multiple cells.

Next, in the LTE system, the UE 5 wirelessly connects to the eNodeB 4 by OFDM (Orthogonal Frequency-Division Multiplexing) access (OFDMA). The OFDMA method is characterized as a two-dimensional multiplexed access method that combines frequency division multiplexing and time division multiplexing. Specifically, the orthogonal frequency axis and time axis channels (subcarriers) are divided and allocated to UE5, and orthogonal subcarriers on the frequency axis are set so that the signal of each subcarrier becomes zero (point 0). To divide. By dividing the subcarriers and assigning them on the frequency axis, it is possible to select another subcarrier that is not affected even if one subcarrier is affected by fading. Subcarriers can be used, and there is an advantage that radio quality can be maintained.

Further, in the OFDMA method, a resource block (Resource Block: hereinafter also referred to as RB) defined on a virtual plane spanning a frequency axis and a time axis is adopted as a radio resource. As shown in FIG. 8, RB is defined as a block obtained by dividing the above plane into a matrix at 180 kHz/0.5 msec, and each block has 12 subcarriers adjacent to each other at 15 kHz intervals on the frequency axis and on the time axis. Includes 1 slot (7 symbols) of the frame. Two RBs (1 msec) adjacent to each other on the time axis are assigned to the UE 5 as one set.

FIG. 9 shows the concept of a wireless data frame of system information distributed using PBCH. As is clear from the fact that the logical channel used is the BCCH, the system information includes broadcast information for control that is broadcast to all target UEs 5. Hereinafter, a method of delivering the notification information will be described. First, as described with reference to FIG. 8, the physical layer of the LTE system has a method of using radio resources by multiplexing time and frequency, and according to the standard, the time axis has a radio frame of 10 ms cycle ( Radio Frame: RF). A unit of 1 ms obtained by dividing a radio frame into 10 is called a subframe, and one subframe is further divided into two slots.

In the LTE system, in order to flexibly change the transmission amount of the above-mentioned broadcast information for each operation/environment, there are fixed broadcast information resources using PBCH and variably usable radio resources using PDSCH. Used in combination. The PBCH, which is a fixed resource, is used here because the broadcast information is defined as the information that the UE 5 first acquires, and the UE 5 needs to be able to receive the notification without receiving the notification from the eNodeB 4. The UE 5 first receives the PBCH, which is a fixed resource, obtains the minimum information for receiving the PDSCH from the PBCH, and reads the broadcast information transmitted on the PDSCH based on that information. Since PDSCH is a variable resource that can be allocated in RB units, the amount of broadcast information transmitted on PDSCH is variable. As a result, the amount of resources used for broadcast information can be changed, and radio resources can be allocated according to the amount of broadcast information that differs depending on the network operation and environment.

Of the broadcast information transmitted by the PBCH, what is called MIB (Master Information Block) is transmitted at the head of the radio frame (that is, subframe number=0) as shown in FIG. , Time resources and frequency resources are always allocated in a fixed manner. The transmission information is, for example, information for receiving other broadcast information (for example, SIB (System Information Block)) by the PDSCH, a radio frame number (SFN: System Frame Number), and the like.

In this embodiment, the eNodeB 4 uses this MIB to deliver to the UE 5, the channel information used for multicast (for example, resource setting information to be allocated to the MCH channel) before the multicast bearer 11 is constructed. The size of the MIB is fixed to 24 bits, but 10 bits of the size are reserved areas, so that it is possible to incorporate multicast channel information by using this reserved area, for example.

The operation of the multicast distribution system 1 of FIG. 1 will be described below. 10 is a communication flowchart, FIG. 11 is a flowchart showing a processing sequence of the EPC 3, and FIG. 12 is a flowchart showing a processing sequence of the eNodeB 4. In FIG. 11, S102 to S105 show a functional flow as the control plane side node device (MME) of the EPC3, and S106 to S111 show a functional flow as the user plane side node device (PGW). First, in S101, the EPC3 system of the core network is activated. Then, in S102, a session start request for establishing the multicast bearer 11 by default is transmitted to the eNodeB 4 (FIG. 10: TS11, multicast bearer establishment instruction).

On the other hand, when the system is activated in S201 of FIG. 12, the eNodeB 4 receives a session start request (multicast bearer establishment instruction) for establishing a multicast bearer from the EPC 3 in S202 (FIG. 10: TS11). Subsequently, in S203 (FIG. 10: TS12), as preparation for establishing a multicast bearer with the UE 5, the multicast channel information is incorporated into the MIB and transmitted to the UE 5 by PBCH. Note that the multicast channel information can be distributed by incorporating it in the SIB on the PDSCH, but the resource setting of the MIB of the PBCH is fixed on both the time axis and the frequency axis. There is an advantage that the distribution procedure is greatly simplified. Here, the “multicast channel information” is information indicating the characteristics of the multicast channel set by the eNodeB 4 when the multicast bearer 11 is constructed, and includes the channel number of the multicast channel, the channel bandwidth, the modulation method, and the transmission rate (transmission). Information such as rate) is included.

The UE 5 receives the MIB and uses the multicast channel information included in the MIB to set the channel for constructing the multicast bearer 11 (TS13). Here, the MIB also includes broadcast information necessary for determining the eNodeB 4 that is the connection destination together with the SIB that is subsequently received, and uses this to determine the eNodeB 4 that is the construction destination of the multicast bearer 11. When the eNodeB 4 is determined, a multicast bearer is built by default (TS14), and a response to start the multicast session is transmitted to the eNodeB 4 (TS15).

When the multicast bearer is constructed in S204 of FIG. 12, the eNodeB 4 transmits a response to start the multicast session to the EPC 3 in S205 (FIG. 10: TS16). In this case, after waiting for the response of the start of the multicast session to be obtained from a predetermined number of UEs 5 (or all the UEs 5 connected to the eNodeB), the response of the start of the multicast session is transmitted from the eNodeB 4 to the EPC 3. May be.

In this way, if the multicast bearer 11 is established between the eNodeB 4 and the UE 5 by default, the EPC 3 receives the response to start the multicast session in S103 of FIG. 11, and constructs the unicast bearer 12 in the eNodeB 4 in S104. A session start request (unicast bearer establishment instruction) for sending (FIG. 10: TS17). The eNodeB 4 receives this in S206 of FIG. 12, and transmits the resource setting information of the unicast bearer 12 to the UE 5 in S207 (FIG. 10: TS18). This resource setting information is transmitted as broadcast information using the above-mentioned MIB and SIB. The UE 5 uses this to set the resource of the unicast bearer 12, constructs the default unicast bearer 12 (FIG. 10: TS19), and transmits a session start response to the eNodeB 4 (FIG. 10: TS20). The construction sequence of the unicast bearer 12 is similar to that of the conventional system, and detailed description thereof will be omitted.

When the multicast bearer 11 (and the unicast bearer) is constructed in this way, distribution of multicast data (multicast content) is started from the media server 6 of FIG. 1 to the UE 5 via the EPC 3, eNodeB 4 and multicast bearer 11. (FIG. 10: TS21-23).

The configuration of the multicast distribution system 1 of FIG. 1 is clear as compared with the configuration of the conventional system of FIG. 13, since the EPC 3 (core network control node device) includes the multicast proxy unit 3b, The MBMS-GW 201 and BM-SC 206 of FIG. 13 are not required as a result of being able to function as a gateway that handles both data of the user plane and the user plane collectively. In addition, the EPC3 (core network control node device) is a single device that is the main processing unit on the control plane side and the user plane side, so that synchronous control of control data and user data is an internal process of the same device. Therefore, it is realized by itself and the MCE 203 provided in the conventional system of FIG. 13 is also unnecessary.

Then, as a result of the number of processing devices in the core network being reduced as described above, the communication flow (operation sequence) of the entire system is significantly simplified as shown in FIG. 10, and the number of steps of the multicast bearer construction setting process is also shown in FIG. It can be seen that the communication flow is significantly reduced as compared with the communication flow of the conventional system of 14.

Furthermore, when the UE 5 (mobile terminal) initially connects to the eNodeB 4 (radio base station), not only the unicast bearer 12 but also the multicast bearer 11 is established by default between the UE 5 and the core network. .. That is, the environment in which the multicast data can be transmitted to the UE 5 is set immediately after the system is started up, and the delay in distribution is less likely to occur.

After the multicast bearer and the unicast bearer are established, the EPC 3 executes the processing of S106 and thereafter in FIG. That is, when the IP packet 300 (see FIG. 4) that forms the distribution data is received in S106, the contents of the destination IP address 301b is read in S107, and the distributed data is a unicast packet or a multicast packet. Determine if there is. If it is a unicast packet, the process proceeds to S111, and the eNodeB 4 is instructed to deliver the unicast bearer 12. On the other hand, if it is a multicast packet, in S108, it is determined whether the received multicast packet is a specific destination multicast packet to which a predetermined destination IP address has been assigned. If it is a specific destination multicast packet, the process proceeds to S110, and the eNodeB 4 is instructed to use the multicast packet as a transmission target multicast packet. On the other hand, if it is not the multicast packet of the specific destination, the process proceeds to S109, and the multicast packet is discarded (that is, distribution is not performed).

The above-described method is, for example, in a content distribution targeting a specific area, a content distribution including emergency information in a disaster area, and the like, eNodeB4 (radio base station: mobile type, etc.) specially provided on the EPC3 (core network). This is effective when you want to perform multicast data distribution only for wireless base stations). In this case, the processing on the eNodeB 4 side is the flow from S210 onward in FIG. That is, when the IP packet received in S210 is a multicast packet, the process proceeds to S211, and the multicast bearer 11 delivers the IP packet to the connected UE 5.

In this case, the multicast (contents) data collected by the EPC 3 has already been selected on the EPC 3 side as to whether or not to be a distribution target. Therefore, the eNodeB 4 need only uniformly distribute the sorted multicast data to the UEs 5 that are connected, regardless of the contents of the destination IP address. In other words, it is not necessary to compare the IP address of the content data with the IP address of the UE 5 that is connected, and the received multicast data can be made to flow to the multicast bearer 11 under construction, so that the distribution process is greatly simplified. Can be promoted.

On the other hand, when the unicast data is received, the processing from S212 is performed. That is, when the UE 5 is connected through the unicast bearer 12 in the cell covered by the eNodeB 4 and the packet of the unicast data (having the IP address of the UE 5) is received in S212, the packet is transmitted in S213. The packet of unicast data is transmitted to the unicast bearer 12. If the process is not completed in S214, the process returns to S210 and the processes up to S213 are repeated.

The embodiments of the present invention have been described above, but they are merely examples, and the present invention is not limited to these.

1 Multicast distribution system 3 EPC (core network control node device)
3a Control unit (MPU)
3b Multicast proxy unit 3d Core side multicast bearer setting instruction unit 3e Core side unicast bearer setting instruction unit 3f Core side transmission/reception unit 3j Multicast packet management unit 4 eNodeB (radio base station)
4a Control unit (MPU)
4d Base station side multicast bearer setting instruction section 4e Base station side unicast bearer setting instruction section 4f Base station side wireless transmission/reception section 4g Unicast transmission/reception I/F
4h Multicast transmission/reception I/F
4i multicast channel information distribution unit 5 UE (mobile terminal)
5b Second multicast bearer construction unit 5c Second unicast bearer construction unit 5f Terminal side wireless transmission/reception unit 5i Multicast channel setting unit 6 Media server 7 E-UTRAN
11 Multicast bearer 12 Unicast bearer

Claims (5)

A core network control node device, a radio base station connected to the core network control node device by a physical line, and a mobile terminal wirelessly connected to the radio base station. EMBMS (evolved Multimedia Broadcast Multicast Service) compliant multicast data can be distributed to terminals,
The core network control node device is also used as a control node of the control plane of the core network and a control node of the user plane, and a core side transmission/reception unit and a multicast proxy for causing the core side transmission/reception unit to receive multicast data distributed from the outside. Unit, a core-side multicast bearer construction instruction unit that transmits a multicast bearer construction instruction at the time of initial connection of the mobile terminal to the core-side transceiver unit toward the radio base station, and a unicast bearer at initial connection of the mobile terminal A core-side unicast bearer construction instructing unit that transmits a construction instruction to the core-side transmitting/receiving unit toward the radio base station,
The wireless base station, a multicast bearer construction instruction receiving unit for receiving the multicast bearer construction instruction, a unicast bearer construction instruction receiving unit for receiving the unicast bearer construction instruction, a base station side wireless transmission/reception unit, and the multicast A base station side multicast bearer construction instruction section for transmitting a bearer construction instruction to the base station side radio transmission/reception section for the mobile terminal and a unicast bearer construction instruction for the mobile terminal side transmission to the base station side radio transmission/reception section And a base station side unicast bearer construction instruction unit,
The mobile terminal receives a terminal side wireless transmission/reception unit and the multicast bearer establishment instruction, thereby causing the terminal side wireless transmission/reception unit to establish a multicast bearer between the wireless base station and the wireless base station. A construction unit and a unicast bearer construction unit that receives the unicast bearer construction instruction to construct a unicast bearer with the radio base station in the terminal side radio transmission/reception unit at an initial connection stage. ,
A multicast distribution system, wherein the multicast data is transmitted to the mobile terminal via the core network control node device, the radio base station and the multicast bearer. The radio base station has a multicast channel information distribution unit that distributes multicast channel information to the mobile terminal using PBCH (Physical Broadcast Channel) prior to the construction of the multicast bearer,
The multicast distribution system according to claim 1, wherein the mobile terminal includes a multicast channel setting unit that receives the multicast channel information and sets a channel of the multicast bearer. The wireless communication system according to claim 2, wherein the multicast channel information is distributed in a form incorporated in a MIB (Master Information Block). The core network node device includes a multicast packet management unit that causes the core-side transmission/reception unit to transmit only a multicast packet to which a predetermined destination IP address is added in the received multicast data as a transmission target multicast packet. The multicast distribution system according to any one of claims 1 to 3. The radio base station, when receiving the multicast data from the core network node device, transmits the multicast data to the connected mobile terminal by the multicast bearer regardless of the assigned destination address. The described multicast distribution system.

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