WO2007032290A1

WO2007032290A1 - Data transmitting system, data transmitting method, radio control apparatus, base station and mobile station

Info

Publication number: WO2007032290A1
Application number: PCT/JP2006/317907
Authority: WO
Inventors: Masayuki Motegi; Yasuhiro Kato; Minami Ishii; Takehiro Nakamura
Original assignee: Ntt Docomo, Inc.
Priority date: 2005-09-14
Filing date: 2006-09-08
Publication date: 2007-03-22
Also published as: JP2007081885A; TWI333350B; TW200721729A

Abstract

A data transmitting system comprising a radio control apparatus, a plurality of base stations and at least one mobile station, wherein the same user common data is delivered, by use of a code-spread OFDM scheme, from the base stations to the at-least-one mobile station. The radio control apparatus comprises a means that stores the received user common data; and a means that notifies the base stations, which are connected to the radio control apparatus, of a common scramble code that is common to the base stations. Each of the base stations has a means that uses the common scramble code, which has been notified of, to spread the user common data and then wirelessly transmits the spread user common data to the at-least-one mobile station; and a means that notifies the at-least-one mobile station of the established common scramble code.

Description

Specification

Data transmission system, data transmission method, radio control apparatus, base station, and mobile station

Technical field

TECHNICAL FIELD [0001] The present invention generally relates to the technical field of wireless data transmission, and more particularly to a data transmission system, a base station, and a data transmission method for transmitting content of a multimedia broadcast / multicast service (MBMS).

Background art

[0002] In recent mobile communication systems, a large-capacity multimedia service based on a packet switching method that can be achieved only with a circuit-switched voice service has begun to be provided. The 3rd Generation Standards Organization (3GPP) standardizes MBMS in packet-switched systems and publishes related architectures and radio channel configurations (see Non-Patent Document 1).

A mobile station, a base station, and a radio network controller (RNC: Radio Network Controller) constitute a radio access network (RAN: Radio Access Network). From the perspective of delivering MBMS content, the RNC may be called an MBMS server. The MBMS server is connected to the broadcast multicast service center (BM-SC) through some network.

[0004] A mobile station (UE) under the control of a base station or Node B (Node B) receives an MB MS notification indicator (NI) that prompts the user to join the MBMS. The mobile station selects the service of interest (for example, news broadcast) received from the NI, notifies the base station to that effect, and executes the procedure for joining the service. . In this type of conventional system, a cell group identifier (Cell Group Id) is assigned to each MBMS content transmitted between one MBMS server, and one PDCP and RLC are shared within the group. When combining or soft combining at cell or sector boundaries, each of the MBMS content delivered from multiple asynchronous cells 1 Combined using LI combining timing specified by MBMS Neighboring Cell Information.

Non-Patent Document 1: 3GPP interface standard, 3GPP “TS25.346”, “TS25.331”, Internet URL: http://www.3gpp.org>

Disclosure of the invention

Problems to be solved by the invention

[0005] In future mobile communication systems that have started discussions at the 3rd Generation Standardization Organization (3GPP), the Orthogonal Frequency Division Multiplexing (OFDM) scheme is promising as a downlink transmission scheme. . In the OFDM method, delayed waves that arrive within the Guard Interval (GI) period can be combined without interfering with each other. For this reason, it is also being discussed that MBMS content can be transmitted simultaneously from multiple cells using the OFDM method, and MBMS content can be synthesized at the cell edge to improve performance. In this case, the MBMS service area that distributes the same content is covered by one or more cells, and the cell boundary and the MBMS service boundary are not necessarily the same. Also, there are many services that a mobile station (UE) may subscribe to, and each MBMS server generally distributes different content. Therefore, especially in the vicinity of the service boundary, different MBMS contents may interfere with each other, resulting in signal quality degradation.

[0006] The present invention has been made to address at least one of the above-mentioned problems, and the problem is that a data transmission system in which the same MBMS content is distributed from a plurality of base stations based on the OFDM scheme is provided. The purpose is to provide a data transmission system, a data transmission method, a radio network controller, a base station, and a mobile station that at least reduce signal quality degradation at the service boundary of MBMS.

Means for solving the problem

[0007] In the present invention, an OFDM system having a radio control device, a plurality of base stations, and one or more mobile stations, and code-spreading the same user common data from the plurality of base stations to one or more mobile stations The data transmission system that is distributed over the network is used. The radio control apparatus includes means for storing received user common data, and means for notifying the plurality of base stations of a common scramble code common to a plurality of base stations connected to the radio control apparatus. Each of the plurality of base stations spreads the user common data with the notified common scramble code and wirelessly transmits it to one or more mobile stations; and means for notifying one or more mobile stations of the common scramble code; Have

The invention's effect

[0008] According to the present invention, in a data transmission system in which the same MBMS content is distributed from one or more base stations using the OFDM scheme, it is possible to at least reduce signal quality degradation at the MBMS service boundary. it can.

Brief Description of Drawings

FIG. 1 is a diagram showing a data transmission system according to an embodiment of the present invention.

FIG. 2 shows a functional block diagram of an MBMS server according to an embodiment of the present invention.

FIG. 3 shows a functional block diagram of a base station according to an embodiment of the present invention.

FIG. 4 is a flowchart showing an example of an operation performed in the MBMS server.

FIG. 5 is a flowchart showing an operation example performed in the base station.

FIG. 6 shows a functional block diagram of a mobile station according to an embodiment of the present invention.

FIG. 7 is a flowchart showing an operation example performed in the mobile station.

FIG. 8 is a functional block diagram of an MBMS server according to an embodiment of the present invention.

Explanation of symbols

[0010] UE mobile station

Node B base station

RNC wireless network controller

RAN radio access network

CN core network

11 Control unit

12 Wired transmission section

13 Scramble code setting section

14 Server communication department

15 MBMS server communication department

16 External input section 17. Self-recollection [5

18 MBMS content identifier

21 Control unit

22 Wireless transmission unit

23 Wired transmission section

24 MBMS content identifier

25 Scramble code setting section

31 Control unit

32 Wireless transmission section

33 Broadcast information analysis unit

34 Data Analysis Department

35 Scramble code setting section

BEST MODE FOR CARRYING OUT THE INVENTION

[0011] According to an aspect of the present invention, a common scrambling code common to a plurality of base stations under the control of a radio network controller (RNC) or an MBMS server is determined. The common scramble code is prepared separately from the scramble code prepared for each cell. User common data (MBMS content) is spread with a common scramble code and transmitted from multiple base stations to one or more mobile stations using OFDM. Since the common scramble code is different for each RNC (for each MBMS service), the mobile station at the cell edge can easily determine whether or not it is at the service boundary, and the MBMS content with multiple adjacent cell powers can also be received. Whether or not in-phase synthesis (soft compiling) should be performed can be easily determined.

[0012] A common scrambling code may be prepared for each MBMS content. In this way, it is possible to synthesize the MBMS content of all cells that deliver the same service.

[0013] The common scramble code may be determined by a management server connected to the radio network controller and managing the scramble code, by an agreement with an adjacent radio network controller, or by external input as station data.

Example 1 [0014] <Communication system>

FIG. 1 shows a communication system according to an embodiment of the present invention. The communication system is composed of a core network (CN) and a radio access network (RAN). The CN includes a routing device (Access Router) and a control station (BM-SC: Broadcast / Multicast-Service Center) that controls the delivery of MBMS content. On the other hand, the RAN communicates with a base station (Node B) through a plurality of radio base stations (Node B), a radio network controller (RNC) or MBMS Sano that controls the plurality of Node Bs, and a radio interface. Multiple mobile station (UE) forces to be configured. The interface between the routing controller and RNC is expressed as Iu. The interface between RNC and base station is expressed in Iub. The interface between RNCs is expressed in Iur. Each interface name assumed in this embodiment is an example, and the present invention is not limited to this.

[0015] The downlink radio interface between the Node B and the UE uses a scheme in which data that has been code spread using a spreading code (scramble code) is transmitted in the OFDM scheme. Cell identification is usually performed using a spreading code called a scramble code. As will be described later, in this embodiment, in addition to the scramble code for each cell, a common scramble code that is commonly used for a plurality of cells is prepared and used to distinguish between different services or different contents. . In the example shown in the figure, base stations of cells Α and Β are connected to one MBMS server, and the same MBMS content is distributed in cells Α and Β. The base station in cell C is connected to another MBMS server, and content that is generally different from the content delivered in cells Α and Β is delivered in cell C. Therefore, a service boundary is formed between cells Α and Β and cell C.

[0016] If the technique of the present embodiment described below is used, the mobile station located near the service boundary (the boundary between cell Α and cell C and the boundary between cell Β and cell C). There is concern that (UE) receives different contents from both cells and the received signal quality is greatly degraded. Since mobile stations located near the boundary between cell A and cell B can receive the same content from both cells, soft compiling can be performed well. This is due to the fact that the UE cannot determine whether or not it is located at the edge of the cell and cannot determine whether or not it is located at the power service boundary. Note that at least MBMS content It is assumed that the transmission timings of all base stations are synchronized with each other regarding distribution.

[0017] Ku MBMS Server>

FIG. 2 shows a functional block diagram of an MBMS server according to an embodiment of the present invention. The MBMS server includes a control unit 11, a wired transmission unit 12, a scramble code setting unit 13, a server communication unit 14, an MBMS server communication unit 15, an external input unit 16, and a storage unit 17.

[0018] The control unit 11 controls each functional entity included in the MBMS server, and controls the operation of the entire MBMS server device. The wired transmission unit 12 has a function of notifying the base station (Node B) of the scramble code determined by the scramble code setting unit 13, a function of communicating with a management server on the network (W), and a function of communicating with an adjacent MBMS server. Have The scramble code setting unit 13 has a function of determining the scramble code of Node B connected to itself (under the MBMS server) when distributing MBMS content. This scramble code is prepared for each MBMS server and is distinguished from the normal scramble code prepared for each cell. The server communication unit 14 has a function of communicating with a management server arranged on the NW, and the management server has a function of managing a scramble code of Node B under the MBMS server. The MBMS server communication unit 15 has a function of communicating with an adjacent MBMS server via an Iur interface. The external input unit 16 has a function of artificially inputting a scramble code such as station data when distributing MBMS content from the outside. The storage unit 17 has a function of storing information used in the RNC, and particularly stores MBMS content received by a higher-level device.

[0019] For convenience of explanation, the MBMS server is illustrated as including all of the server communication unit 14, the MBMS server communication unit 15, and the external input unit 16. This is not essential to the present invention, and at least one of them is included. It only needs to have one function. In this case, the wired transmission unit 12 is provided in the MBMS server among the server communication unit 14, the MBMS server communication unit 15 and the external input unit 16, and should have a function corresponding to that! /.

[0020] Normal scramble code C prepared for each cell and prepared for each MBMS server

CELL

Scramble code C is prepared separately. These may be set completely independently,

MB

Even if there is some relationship.

[0021] Ku Node B> FIG. 3 shows a functional block diagram of a base station (Node B) according to an embodiment of the present invention. Node B includes a control unit 21, a wireless transmission unit 22, a wired transmission unit 23, an MBMS content identification unit 24, and a scramble code setting unit 25.

[0022] The control unit 21 controls each functional entity included in the base station (Node B) and controls the operation of the entire base station (Node B). The wireless transmission unit 22 has a function of distributing MBMS content to mobile stations, and the MBMS content is spread with a scramble code specified by the MBMS server. In this embodiment, the downlink radio channel may be transmitted by OFDM-CDM A (also called MC-CDMA or OFCDM) system as an example! The transmission method is not limited to this, and it may be transmitted by the OFDM method in which the spreading process for the data is performed using a spreading code (scramble code). The wired transmission unit 23 has a function of receiving notification of a scramble code specified by the MBMS server and a function of receiving MBMS content distributed from the MBMS Sano. The MBMS content identification unit 24 stores data transmitted from the MBMS Sano and has a function of identifying whether it is MBMS content capability or not. The scramble code setting unit 25 has a function of setting a scramble code for MBMS content distribution specified by the MBMS server in order to create a downlink radio channel.

[0023] <Operation flow of MBMS server>

FIG. 4 shows an example of the operation flow of the MBMS server according to an embodiment of the present invention. This operation is performed when the MBMS service is started. The MBMS server determines whether to start the MBMS content distribution service (step Sl). This determination may be made based on, for example, whether or not the MBMS server has received a high-level device (such as BM-SC) and has received MBMS content. If No in step S1, the flow ends. If YES, the flow proceeds to step S2, and the MBMS content distribution service is started.

[0024] In step S2, it is determined whether or not to make an inquiry to a management server (for example, 0 & A server) that is placed on the network (NW). As described above, such a management server has a function of managing scramble codes. The MBMS server may, but may or may not be configured to communicate with the management server to determine the scramble code. In the former case, the judgment result in step S2 is YES, and the MBMS server Inquire the server and obtain information about the scramble code. In the latter case, the judgment result in step S2 is NO, and the flow proceeds to step S3.

In step S3, it is determined whether or not to make an inquiry to a neighboring MBMS server. The MB MS server may or may not be configured to negotiate with neighboring MBMS servers when determining the scramble code. In the former case, the judgment result in step S3 is YES, and the MBMS server makes an inquiry to a neighboring MBMS server to obtain information on the scramble code. For example, when one RNC is used by the other RNC, information on the scramble code is obtained. In the latter case, the determination result in step S3 is NO, and the flow proceeds to step S4.

In step S4, it is determined whether or not the scramble code can be artificially input as station data. The MBMS server may or may not be set so that the scramble code is externally input as station data. In the former case, the MBMS server receives external input and obtains information on the scramble code. In the latter case, information on the scramble code is acquired by some other method (step S41).

[0027] In step S5, the scramble code information acquired in each step S2, S3, S4 or S41 is notified to the scramble code setting unit 13 in FIG. Based on this information, the scramble code used under the MBMS server is determined. The determined scramble code is notified to a plurality of base stations (Node B) connected to the MBMS server (step S6), and the flow ends.

[0028] For convenience of explanation, the force that the flow is drawn so that the MBMS server can execute all the steps S2, S3, S4 and S41. This is not essential to the present invention. This is because it is only necessary to set a scramble code for the service in some way after the start of the service is determined in step S1. When using step S2 or S3, the system can set the scramble code under the MBMS server autonomously, so it can be set automatically. In Steps S2 and S3, the additional calorie function is required to set the scramble code. In Step S4, no additional function is required. In addition, when two or more of steps S2, S3, S4, and S41 are executable, the order in which the procedures are executed is not limited to that shown in the figure, and the order in which the steps are executed may be changed. Good. Step S2, S3, S4 or S41 or their combination power The information obtained may relate to one scramble code or may be a plurality of scramble code candidates that can be used. In the latter case, it is determined in step S5 which scrambling code should be used in the end.

[0029] Operation Flow of Node B>

FIG. 5 is a flowchart showing an operation example of the base station (Node B) according to one embodiment of the present invention. This example is performed when the MBMS service is started.

In step S1, it is determined whether or not a scramble code related to MBMS is notified from the MBMS server to which the base station (Node B) belongs. As a result of the determination in step S1, if the MB MS server power is not notified of the scramble code, the flow ends, and if it is notified, the flow proceeds to step S2. In step S2, the base station (Node B) sets the specified scramble code in the radio transmitter. The fact that the scramble code is used for delivery of MBMS content is reported to the mobile station (UE) by broadcast information. As an example, the power assumed to be notified by the notification information S is not limited to this. It may be a method of notifying by the signaling at the start of the MBMS service. In step S3, it is determined whether there is MBMS content to be transmitted to the UE. If there is MBMS content to be transmitted as a result of the determination in step S3, the MBMS content is transmitted using the scramble code set for that purpose (step S4). If there is no MBMS content to be transmitted as a result of the determination in step S3 and there is user data to be transmitted, user data is transmitted using a normal scramble code set for each cell. (Step S5). Note that the normal scramble code set for each cell and the scramble code notified in step SI are not the same.

FIG. 6 shows a functional block diagram of a mobile station (UE) according to an embodiment of the present invention. The UE includes a control unit 31, a radio transmission unit 32, a broadcast information analysis unit 33, a data analysis unit 34, and a scramble code setting unit 35.

[0032] The control unit 31 controls each functional entity included in the UE and controls the operation of the entire UE. The radio transmission unit 32 has a function of receiving broadcast information in a cell in the serving cell, and a function of despreading MBMS content with a specified scramble code and receiving it. In this example The downlink radio channel is transmitted by the OFDM method in which data is spread using a spreading code (scramble code). The broadcast information analysis unit 33 has a function of analyzing a common scramble code for MBMS broadcast by broadcast information. The data analysis unit 34 has a function of analyzing data transmitted on the data channel. For example, the data analysis unit 34 analyzes the identifier that is coded on the SCCH attached to the data channel. Analyze the type. The scramble code setting unit 35 has a function of setting a scramble code according to the data type transmitted on the data channel. More specifically, if the transmitted data is MBMS content, a “common scrambling code” common to a plurality of cells according to the present embodiment is used. If the transmitted data is not MBMS content, it is per cell. Scramble codes are used.

[0033] FIG. 7 is a flowchart showing an operation example of a mobile station (UE) according to an embodiment of the present invention.

In step S1, it is determined whether or not the mobile station has received the broadcast information. As a result of the determination in step S1, if the broadcast information has not been received, the flow ends. If it has been received, the flow proceeds to step S2. In step S2, the UE sets the specified scramble code in the radio receiver. In step S3, the UE determines the type of data transmitted on the data channel. As a result of the determination in step S3, if the data type is MBMS content, the MBMS content is received using the common scramble code set for that purpose (step S4). If it is determined in step S3 that the data type is normal user data that is not MBMS content, the user data is received using a normal scramble code set for each cell (step S5). ).

[0035] According to this embodiment, a common scramble code is prepared for each MBMS server (for each service area). Therefore, the mobile station (UE) located at the cell edge determines the difference of the common scrambling code between cells, and if it is the same, the UE is in the same service area and executes soft compiling. If the common scramble code is different between cells, the cell edge is also a service boundary, so the UE should not perform soft compiling! By performing such operations, the UE can effectively avoid unnecessary combining processing of received signals at the service boundary. Example 2

[0036] In the first embodiment, a scramble code is prepared for each MBMS server. In the second embodiment, a scramble code is prepared for each MBMS content to be distributed.

[0037] Ku MBMS Server>

FIG. 8 shows a functional block diagram of an MBMS server according to an embodiment of the present invention. The MBMS server has the same control unit 11, wired transmission unit 12, scramble code setting unit 13, server communication unit 14, MBMS server communication unit 15, external input unit 16 and storage unit 17 as those described in FIG. In addition to this, an MBMS content identification unit 18 is provided. In the present embodiment, each functional unit has the following functions.

The control unit 11 controls each functional entity included in the MBMS server, and controls the operation of the entire MBMS server device. The wired transmission unit 12 has a function of notifying the base station (Node B) of the scramble code determined by the scramble code setting unit 13, a function of communicating with a management server on the network (W), and a function of communicating with an adjacent MBMS server. Have The scramble code setting unit 13 has a function of determining the scramble code of Node B connected to itself (under the MBMS server) when distributing MBMS content. This scramble code is determined for each MBMS content. The server communication unit 14 is arranged on the NW and has a function of communicating with the management server. The management server has a function of managing the scramble code of Node B under the MBMS server. The MBMS server communication unit 15 has a function of communicating with an adjacent MBMS server via an Iur interface. The external input unit 16 has a function of artificially inputting a scramble code such as station data when distributing MBMS content with an external force. The storage unit 17 has a function of storing information used by the MBMS server, and particularly stores MBMS content received by a higher-level device. The MBMS content identification unit 18 has a function of identifying the MBMS content to which UEs under the MBMS server have joined. In other words, the MBMS server knows which UE subscribes to which service and which service contains which content. In other words, the MBMS server keeps track of the services that it subscribes to for each UE and the content it contains for each service.

[0039] Ku Node B> The base station (Node B) used in this embodiment is mainly different in the setting method of the power scramble code having the same function as the base station (FIG. 3) used in the first embodiment. Node B has a control unit 21, a wireless transmission unit 22, a wired transmission unit 23, an MBMS content identification unit 24, and a scramble code setting unit 25 as shown in FIG. In the present embodiment, each functional unit has the following functions.

[0040] The control unit 21 controls each functional entity included in the Node B, and controls the operation of the entire Node B. The wireless transmission unit 22 has a function of distributing MBMS content to mobile stations, and the MBMS content is spread with a scramble code designated by the MBMS server. Also in this embodiment, the downlink channel is transmitted by the OFDM method in which the spreading process is performed on the data using the spreading code (scramble code). The wired transmission unit 23 has a function of receiving notification of a scramble code designated by the MBMS server and a function of receiving MBMS content distributed from MBMS Sano. The MBMS content identification unit 24 has a function of storing data transmitted from the MBMS server and identifying whether or not the MBMS content is strong. The scramble code setting unit 25 has a function of setting a scramble code for MBMS content distribution designated by the MBMS server for each MBMS content in order to create a downlink radio channel.

[0041] According to the present embodiment, a scramble code is set for each content. As mentioned above, different MBMS servers generally have different power and distributed content. Therefore, the UE can distinguish between different contents using the scramble code, and can avoid unnecessary combining processing of received signals at the service boundary. This is the same as in the first embodiment. However, in this embodiment, a scramble code is prepared for each content, not for each MBMS server. Therefore, even if the UE is at the service boundary, if the same content happens to be distributed from both service areas (MBMS servers), the scramble codes are the same, and the distribution contents of both are appropriately combined. It turns out that we can do it and we can soft-connose them. In other words, according to the present embodiment, the mobile station can synthesize signals that also come from all cell powers that distribute the same content.

[0042] It should be noted that the present invention is not limited to the above embodiments, but within the scope of the claims. Various modifications and applications are possible.

This international application claims priority based on Japanese Patent Application No. 2005-267671 filed on September 14, 2005, the entire contents of which are incorporated herein by reference.

Claims

The scope of the claims

[1] A data transmission device that has a radio controller, a plurality of base stations, and one or more mobile stations, and distributes the same common user data from a plurality of base stations to one or more mobile stations using code-spread OFDM. Data transmission system,

The radio control apparatus has means for storing received user common data, and means for notifying the base stations of a common scrambling code common to a plurality of base stations connected to the radio control apparatus. ,

Each of the plurality of base stations spreads the user common data with the notified common scramble code and wirelessly transmits it to one or more mobile stations, and the set common scrambling code to one or more mobile stations. And means for notifying

A data transmission system characterized by that.

[2] A radio control apparatus connected to the plurality of base stations used in a data transmission system that distributes the same user common data from a plurality of base stations to one or more mobile stations using the code-spread OFDM method. There,

Means for storing user common data;

Means for distributing common user data to the plurality of base stations;

Means for notifying the plurality of base stations of a common scramble code common to the plurality of base stations;

A wireless control device comprising:

[3] The apparatus further includes means for determining whether the received data is common user data, and the common scramble code is prepared for each common user data.

The wireless control device according to claim 2, wherein:

[4] Common scramble code power Determined by the management server that manages the scramble code, by agreement with an adjacent radio network controller, or by external input as station data

The wireless control device according to claim 2, wherein:

[5] Used in a data transmission system that distributes the same user-common data from multiple base stations connected to a radio network controller to one or more mobile stations using the code-spread OFDM method. A base station,

Means for receiving information of a common scramble code common to a plurality of base stations from the radio controller;

Means for spreading the user common data with the notified common scramble code and wirelessly transmitting to one or more mobile stations;

Means for notifying one or more mobile stations of a common scramble code;

A base station characterized by comprising:

[6] The common scramble code is prepared for each user common data

The base station according to claim 5, wherein:

[7] The apparatus further includes means for spreading user data different from the user common data with a scramble code prepared for each cell and wirelessly transmitting the data to one or more mobile stations.

The base station according to claim 5, wherein:

[8] A mobile station that is used in a data transmission system that distributes data using a code-spread OFDM system that is connected to a radio network controller.

Means for receiving broadcast information including information on a common scramble code common to the plurality of base stations;

Means for determining whether or not the data type is user common data common to one or more users;

If the data type is user common data, the data is despread with the common scramble code. If the received data type is not user common data, the data is scrambled for each base station. A means of despreading with a code;

A mobile station characterized by comprising:

[9] A data transmission device having a radio controller, a plurality of base stations, and one or more mobile stations, and distributing the same user common data from the plurality of base stations to one or more mobile stations using code-spread OFDM. Data transmission method,

The radio control apparatus stores the received user common data, notifies the plurality of base stations of a common scramble code common to a plurality of base stations connected to the radio control apparatus, Each of the plurality of base stations spreads user common data with a common scramble code notified to 1S, and wirelessly transmits to one or more mobile stations,

At least one of the one or more mobile stations despread and demodulate the received user common data with the common scramble code also notified of the one or more base station powers.

A data transmission method characterized by the above.