JP5599369B2 - Radio base station and communication method - Google Patents

Description

  The present invention relates to a radio base station and a communication method that constitute a radio communication system that performs radio transmission and reception in cooperation between a plurality of cells.

  The LTE-Advanced (Long Term Evolution-Advanced) system, which is being standardized by 3GPP (3rd Generation Partnership Project), supports CoMP (Coordinated MultiPoint transmission / reception) that performs wireless transmission and reception in cooperation between multiple cells. Is done. CoMP includes (1) JP (Joint Processing) in which data is transmitted simultaneously or selectively from a plurality of cells, and (2) data transmission gain of the cell in consideration of scheduling and beamforming in a certain cell in other cells. There are two transmission modes of CS / CB (Coordinated Scheduling / Coordinated Beamforming) that improve the frequency (Non-Patent Document 1). In any transmission mode, a high-speed inter-base station line is required to share information between base stations.

  In the LTE-Advanced system and its predecessor LTE system, a terminal detects and reports a neighboring cell, and automatically configures an interface between base stations for performing handover control with the base station forming the neighboring cell. An ANR (Automatic Neighbor Relation) function is defined (Non-Patent Document 2, Non-Patent Document 3).

  In the invention described in Patent Document 1, CoMP based on the number of connected terminals in the neighboring cell, the received signal strength of the neighboring cell in the terminal, the number of times of reporting of the terminal, etc. By determining a set of neighboring cells (CoMP Cooperating Set) to perform CoMP and negotiating whether or not CoMP can be performed with the base station forming the neighboring cell performing CoMP, the above CoMP mode can be negotiated. Cooperating Set settings and inter-base station interface settings required for CoMP can be automatically performed.

International Publication No. 2011/016560

“3GPP TR 36.814” Ver.9.0.0 (2010-03-30) “3GPP TS 36.413” Ver.9.5.1 (2011-01-06) “3GPP TS 36.423” Ver.9.5.0 (2010-12-21)

  While it is necessary for CoMP to be able to maintain sufficient wireless communication quality for a terminal to perform transmission / reception with a plurality of cells, control information necessary for CoMP is transmitted between a plurality of base stations forming a plurality of cells communicating with the terminal. It must be replaceable within a predetermined delay time. Therefore, when configuring the CoMP Cooperation Set, not only the measurement of the wireless communication quality with the neighboring cell by the terminal, but also the line between the base station communicating with the terminal and the base station to be added to the CoMP Cooperation Set It is necessary to verify whether or not the transmission characteristics are sufficient to perform the transmission.

  The present invention has been made in view of the above, and information that needs to be shared for CoMP can be exchanged within a predetermined delay time among adjacent radio base stations detected by a terminal in the ANR function. An object of the present invention is to obtain a radio base station and a communication method that perform CoMP by selecting an appropriate radio base station.

  In order to solve the above-described problems and achieve the object, the present invention is necessary for handover control of a mobile terminal when an adjacent base station that is an adjacent radio base station is detected by a subordinate mobile terminal. A radio base station having a function of setting a line for transmitting / receiving information with the adjacent base station and a cooperative function of performing radio transmission / reception in cooperation with other radio base stations, which is necessary for the handover control. Control information when wireless transmission / reception is performed in cooperation with the adjacent base station when exchanging information for setting the line in the operation of setting a line for transmitting / receiving various information with the adjacent base station. Information on the cooperative operation line for exchanging data and information for transmission delay measurement on the cooperative operation line is also exchanged, and the transmission delay on the cooperative operation line is measured. And, based on the measurement result, and judging whether or not to perform radio transmission and reception in cooperation with the neighboring base station.

  According to the present invention, a cooperative operation is performed for adjacent cells (adjacent base stations capable of exchanging information necessary for the cooperative operation within a predetermined time) capable of setting a line having transmission characteristics sufficient to perform the cooperative operation. There is an effect that a radio base station can be realized.

FIG. 1 is a diagram illustrating a configuration example of a wireless communication system including a wireless base station according to the present invention. FIG. 2 is a diagram showing a procedure for establishing an interface between devices using a conventional ANR function. FIG. 3 is a diagram showing an example of an inter-device interface establishment procedure by the radio base station according to the present invention.

  Hereinafter, embodiments of a radio base station and a communication method according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a diagram illustrating a configuration example of a radio communication system including a radio base station according to the present invention. In the present embodiment, a CoMP Cooperation Set configuration method when the wireless communication system is a 3GPP LTE or LTE-Advanced system will be described.

  As shown in FIG. 1, the radio communication system of the present embodiment includes core network devices (MME) 11 and 12 and radio base stations (eNBs) 21 and 22. In addition, the eNB 21 and the eNB 22 form cells (Cells) 41 and 42, which are wireless communication areas, respectively. The mobile terminal (UE) 3 performs radio communication with the eNB 21 in the cell 41. The cell 42 is adjacent to the cell 41, and the UE 3 can move from the cell 41 to the cell 42 or from the cell 42 to the cell 41 while maintaining communication by performing a handover process between the eNB 21 and the eNB 22. it can.

  The eNB 21 and the eNB 22 cooperate to perform CoMP between the cell 41 and the cell 42 and the UE 3. However, the eNB 21 does not know that the cell 42 is adjacent to the own cell (cell 41), and the UE 3 can be handed over from the cell 41 to the cell 42 or can perform CoMP with the eNB 22. It shall not be possible.

  The eNB 21 is connected to the host MME 11 via the inter-device interface 101. Similarly, the eNB 22 is connected to the MME 12 via the inter-device interface 102. The MME 11 and the MME 12 are each connected to a plurality of radio base stations (eNBs) not shown in the figure, manage the area information of the mobile terminal (UE), receive processing, and user data according to the service provided to the mobile terminal (voice, Video stream, packet, etc.) are routed. The MME 11 and the MME 12 are connected by the inter-device interface 103, and the handover control between the cell 41 and the cell 42 can be performed by the eNB 21 and the eNB 22 communicating indirectly via the inter-device interfaces 101 to 103. The MME 11 and the MME 12 also use the interface 103 when taking over information related to the UE 3.

  The ANR function in the LTE / LTE-Advanced system adds the adjacent cell 42 detected by the UE 3 as an adjacent cell of the cell 41, and establishes an inter-device interface 104 (see FIG. 1) between the eNB 21 and the eNB 22. Here, a conventional procedure when the inter-device interface 104 is established by the ANR function will be described with reference to FIG.

  In the conventional procedure for establishing an inter-device interface between eNBs forming adjacent cells, first, the broadcast channel transmitted by the UE 3 on the adjacent cell 42 of the cell 41 in which the UE 3 is located. And the wide area cell ID and location registration area ID (hereinafter referred to as cell information) of the cell 42 transmitted on the broadcast channel are acquired (step S1).

  Next, the UE 3 reports the reception quality / cell information measured / acquired in step S1 to the eNB 21 in wireless communication using a MEASUREMENT REPORT (message) (step S2).

  The eNB 21 that has received the report from the UE 3 determines whether or not to add the cell 42 to the neighboring cell list of the own cell (cell 41) from the reception quality / cell information of the cell 42 received from the UE 3. Various implementations are possible for the determination method. For example, a threshold is set for the reception quality or similar information and the number of times the information is received, and information indicating that the reception quality or the like is equal to or greater than the threshold is continuously applied for a predetermined number of times. Can be added to the neighbor cell list. When it is decided to add to the neighbor cell list, the eNB 21 confirms the wide area cell ID received from the UE 3 and acquires the base station ID of the eNB 22 forming the cell 42. Furthermore, base station ID of acquired eNB22 is transmitted to MME11 by eNB CONFIGURATION TRANSFER together with location registration area ID received from UE3. The eNB CONFIGURATION TRANSFER includes an SCTP endpoint information request for requesting information for the eNB 21 to establish the inter-device interface 104 to the base station (eNB 22) specified by the base station ID (step S3). .

  MME11 which received the said message from eNB21 confirms the location registration area ID contained in the said message, specifies MME which should transfer the said message, with respect to MME12 which is the specified MME, message as CONFIGURATION TRANSFER TUNEL ( The base station ID and the location registration area ID) are transferred (step S4).

  MME12 which received the said message transferred by MME11 transfers the said message to eNB22 as MME CONFIGURATION TRANSFER (step S5).

  The eNB 22 that has received the message forwarded by the MME 12 transmits the SCTP endpoint information (IP address, SCTP port number) on the eNB 22 side necessary for establishing the interface 104 with the eNB 21 to the MME 12 by the eNB CONFIGURATION TRANSFER ( Step S6).

  MME12 which received the said message from eNB22 transfers the said message to MME11 as CONFIGURATION TRANSFER TUNEL (step S7).

  MME11 which received the said message transferred by MME12 transfers the said received message to eNB21 as MME CONFIGURATION TRANSFER (step S8).

  The eNB 21 that has received the message transferred by the MME 11 and acquired the information for establishing the inter-device interface 104 transmitted from the eNB 22 (the SCTP endpoint information on the eNB 22 side) uses this information to communicate with the eNB 22 The inter-device interface 104 is established between them (step S9).

  The eNB 21 further notifies the eNB 22 of neighboring cell information (cell information of the cell 41) for the cell 42 via the established inter-device interface 104 (step S10).

  When receiving the neighboring cell information from the eNB 21, the eNB 22 notifies the eNB 21 of neighboring cell information (cell information of the cell 42) for the cell 41 via the interface 104 (step S <b> 11).

  As described above, in the conventional LTE / LTE-Advanced system, the exchange of neighboring cell information and the establishment of the inter-base station interface 104 are automatically performed by the ANR function.

  Next, the configuration procedure of the CoMP Cooperation Set in the radio communication system of the present embodiment will be described using FIG. 1 and FIG. FIG. 3 is a diagram illustrating an example of a configuration procedure of the CoMP Cooperation Set using the ANR function in the radio communication system according to the present embodiment. In FIG. 3, the same steps as those shown in FIG. 2 are assigned the same step numbers. Description of the processing of the same step number as in FIG. 2 is omitted.

  In the radio communication system of the present embodiment, when the eNB 21 receives the cell information and reception quality information transmitted from the UE 3 in step S2, the same information as the conventional ANR function (see step S3 in FIG. 2), that is, A message addressed to the eNB 22 including the base station ID, location registration area ID, SCTP (Stream Control Transmission Protocol) endpoint information request, and further including a delay measurement request is transmitted to the MME 11 as an eNB CONFIGURATION TRANSFER (step S3a). The delay measurement request includes control information when performing CoMP between the eNB 21 and the eNB 22, information on a line used for data exchange, and information on a means for measuring the transmission delay of the line. The control information used for CoMP and the line information used for data exchange include, for example, the IP address on the eNB 21 side and the port number of a transmission protocol (such as SCTP (Stream Control Transmission Protocol) or GTP (GPRS Tunneling Protocol)) Or a set of identifiers. The information on the means for measuring the transmission delay includes, for example, a delay measurement method that can be used by the eNB 21 (PING (Packet Internet Groper), NTP (Network Time Protocol), measurement by exchanging fixed messages, etc.) A list of means). Further, when the line for exchanging control information and data at the time of CoMP and the line used for delay measurement are different, as part of the information on the transmission measurement means, the line information for measuring the line delay (IP address or protocol port number). Include identifier etc.)

  When the eNB 22 receives the information transmitted from the eNB 21 in step S3a, the same information as the conventional ANR function (see step S6 in FIG. 2), that is, the base station ID, the location registration area ID, and the SCTP endpoint information request And a message addressed to the eNB 21 including the delay measurement response is transmitted to the MME 12 as an eNB CONFIGURATION TRANSFER (step S6a). In the delay measurement, the control information at the time of CoMP execution on the eNB 22 side and the information on the line used for exchanging data and the transmission delay of this line are measured in the same manner as the message delay measurement request transmitted in step S3a. Information about the means.

  When the eNB 21 receives the information transmitted from the eNB 22 in the above step S6a, the control information at the time of CoMP implementation on the eNB 22 side included in the received delay measurement response and the information on the line used for exchanging data and the transmission delay of this line The transmission delay measurement method is determined on the basis of the information on the means for measuring the transmission delay, and the transmission delay is measured for the line (or a plurality of transmission delay measurement targets) (step S21). If the transmission delay is larger than the predetermined value (threshold value) as a result of the measurement, the eNB 21 determines that CoMP cannot be performed with the eNB 22 and does not add the eNB 22 (cell 42) to the CoMP Cooperation Set. On the other hand, when the transmission delay is smaller than the predetermined value as a result of the measurement, it is determined that CoMP can be performed with the eNB 22, and the eNB 22 (cell 42) is added to the CoMP Cooperation Set.

  When the eNB 21 is added to the CoMP Cooperation Set in step S21, the eNB 21 further establishes the inter-device interface 104 as a control information / data exchange line used for CoMP with the eNB 22 (step S9a). This line may be individually established for control information exchange and data exchange, or may be the same. Moreover, it may be the same as the line established between eNB 21 and eNB 22 for conventional handover control. If the eNB 22 is not added to the CoMP Cooperation Set in step S21, this step is the same as the conventional ANR function (step S9 in FIG. 2).

  Subsequent processing is the same as in the prior art. In step S10, the eNB 21 may notify the eNB 22 of CoMP execution or non-execution. Moreover, when implementing CoMP, you may negotiate the transmission mode used by CoMP between eNB21 and eNB22 in step S10-S11.

  As described above, in the automatic configuration procedure of the CoMP Cooperation Set in the radio communication system of the present embodiment, control information and data are exchanged at the time of CoMP implementation to the base station forming the neighboring cell detected and reported by the UE 3 by the ANR function. Requesting the information of the line used for transmission and the information of the means for measuring the delay of the line, measuring the transmission delay based on the line information and the information of the line delay measuring means notified as the response, and transmitting Adjacent cells are added to the CoMP Cooperation Set when the delay is less than or equal to the predetermined value, so that it has sufficient transmission characteristics to perform CoMP at the inter-base station interface while automatically configuring the CoMP Cooperation Set. CoMP can be performed only with neighboring cells (cells of neighboring base stations that can exchange information necessary for CoMP with low delay).

  In this embodiment, when a neighboring cell is newly detected by the ANR function, the transmission delay of the inter-device interface 104 used at the time of CoMP is measured and established, but the inter-device interface 104 is established. After that, the transmission delay may be measured periodically, and CoMP execution / non-execution may be switched based on the measurement result. For example, after the transmission delay measured in step S21 is equal to or less than a predetermined value and the control information / data exchange line at the time of CoMP is established and CoMP is started, the transmission delay of the interface 104 is periodically measured to determine the transmission delay. When is larger than a predetermined value, CoMP is stopped. Conversely, even when CoMP is not implemented, the transmission delay of the interface 104 is periodically measured, and when the transmission delay becomes smaller than a predetermined value, CoMP is started. As a result, even in an environment where the state (transmission delay) of the line (control information / data exchange line during CoMP) fluctuates, a radio base station that implements CoMP can be appropriately selected according to the line state.

  In the present embodiment, the line between the eNB 21 and the eNB 22 (the inter-device interface 104) has been described assuming a wired line. However, a radio transmission section may be included between the eNB 21 and the eNB 22. For example, when the eNB 22 is a relay base station employed in the LTE-Advanced system, there is a DeNB (Donor eNB) between the eNB 22 and the eNB 21 (the eNB 21 may be a DeNB of the eNB 22), and the eNB 22 and the DeNB Is a combination of wireless transmission and wired transmission between the DeNB and the eNB 21 (the same applies to the case of the eNB 21 and the relay base station), but instead of determining the CoMP implementation based on the measurement result of the transmission delay between the eNB 21 and the eNB 22 There is no.

  As described above, the radio base station according to the present invention is suitable for realizing a radio communication system that performs radio communication in cooperation between a plurality of adjacent cells.

3 Mobile terminal (UE)
11, 12 Core network equipment (MME)
21, 22 Radio base station (eNB)
41, 42 cell
101, 102, 103, 104 Interface between devices

Claims (10)

When an adjacent base station that is an adjacent radio base station is detected by a subordinate mobile terminal, a line for transmitting and receiving information necessary for handover control of the mobile terminal is set up with the adjacent base station A wireless base station having a function and a cooperative function of performing wireless transmission and reception in cooperation with another wireless base station,
In the operation of setting a line for transmitting / receiving information necessary for the handover control with an adjacent base station, when exchanging information for the line setting, wireless transmission / reception is performed in cooperation with the adjacent base station. Control information and data for cooperative operation for exchanging data and information for transmission delay measurement in the cooperative operation line are also exchanged, and the transmission delay in the cooperative operation line is measured. Then, based on the measurement result, determine whether to perform radio transmission / reception in cooperation with the adjacent base station ,
The radio base station characterized in that the information for transmission delay measurement in the cooperative operation line includes a list of usable transmission delay measurement methods . When an adjacent base station that is an adjacent radio base station is detected by a subordinate mobile terminal, a line for transmitting and receiving information necessary for handover control of the mobile terminal is set up with the adjacent base station A wireless base station having a function and a cooperative function of performing wireless transmission and reception in cooperation with another wireless base station,
  In the operation of setting a line for transmitting / receiving information necessary for the handover control with an adjacent base station, when exchanging information for the line setting, wireless transmission / reception is performed in cooperation with the adjacent base station. Control information and data for cooperative operation for exchanging data and information for transmission delay measurement in the cooperative operation line are also exchanged, and the transmission delay in the cooperative operation line is measured. Then, based on the measurement result, determine whether to perform radio transmission / reception in cooperation with the adjacent base station,
  While setting up a cooperative operation line with all adjacent base stations, periodically measuring the transmission delay in each cooperative operation line and obtaining the measurement result, the adjacent base station is based on the measurement result. Re-determine whether or not to perform wireless transmission and reception in cooperation with, and adaptively change the neighboring base station to perform wireless transmission and reception in cooperation
  A wireless base station characterized by that. The radio base station according to claim 2 , wherein the information for transmission delay measurement in the cooperative operation line includes a list of usable transmission delay measurement methods. The radio base station according to claim 1 , wherein a line for transmitting and receiving information necessary for the handover control is used as the cooperative operation line.   The cooperation function is CoMP (Coordinated MultiPoint transmission / reception) in LTE-Advanced (Long Term Evolution-Advanced) system of 3GPP (3rd Generation Partnership Project). The radio base station described in 1. When an adjacent base station that is an adjacent radio base station is detected by a subordinate mobile terminal, a line for transmitting and receiving information necessary for handover control of the mobile terminal is set up with the adjacent base station In a radio communication system comprising a radio base station and a core network device that accommodates the radio base station, a communication method when the radio base station performs radio transmission / reception in cooperation with an adjacent base station,
As a process for determining whether each radio base station performs radio transmission / reception in cooperation with an adjacent base station detected by a subordinate mobile terminal,
Control when performing transmission / reception in cooperation with the adjacent base station together with information for setting the line when setting a line for transmitting / receiving information necessary for the handover control with the adjacent base station An information exchanging step of exchanging information of a cooperative operation line for exchanging information and data and information for transmission delay measurement in the cooperative operation line via the core network device;
A delay measurement step of measuring a transmission delay in the cooperative operation line using the information exchanged in the information exchange step;
A determination step of determining whether to perform radio transmission / reception in cooperation with the adjacent base station based on the measurement result of the transmission delay;
Only including,
The information for transmission delay measurement in the cooperative operation line includes a list of transmission delay measurement methods that can be used by a radio base station that accommodates a mobile terminal that has detected an adjacent base station.
A communication method characterized by the above.   When an adjacent base station that is an adjacent radio base station is detected by a subordinate mobile terminal, a line for transmitting and receiving information necessary for handover control of the mobile terminal is set up with the adjacent base station In a radio communication system comprising a radio base station and a core network device that accommodates the radio base station, a communication method when the radio base station performs radio transmission / reception in cooperation with an adjacent base station,
  As a process for determining whether each radio base station performs radio transmission / reception in cooperation with an adjacent base station detected by a subordinate mobile terminal,
  Control when performing transmission / reception in cooperation with the adjacent base station together with information for setting the line when setting a line for transmitting / receiving information necessary for the handover control with the adjacent base station An information exchanging step of exchanging information of a cooperative operation line for exchanging information and data and information for transmission delay measurement in the cooperative operation line via the core network device;
  A delay measurement step of measuring a transmission delay in the cooperative operation line using the information exchanged in the information exchange step;
  A determination step of determining whether to perform radio transmission / reception in cooperation with the adjacent base station based on the measurement result of the transmission delay;
  Including
  Each radio base station sets up a line for cooperative operation with all adjacent base stations, periodically measures the transmission delay in each line for cooperative operation, and acquires the measurement result every time it obtains the measurement result. Re-determine whether or not to perform wireless transmission / reception in cooperation with neighboring base stations based on, and adaptively change the neighboring base station to perform wireless transmission / reception in cooperation
  A communication method characterized by the above. The information for transmission delay measurement in the cooperative operation line includes a list of transmission delay measurement methods that can be used by a radio base station that accommodates a mobile terminal that has detected an adjacent base station. 8. The communication method according to 7 . The communication method according to claim 6 , 7 or 8 , wherein a line for transmitting and receiving information necessary for the handover control is used as the cooperative operation line.   The function of performing wireless transmission / reception in cooperation with an adjacent base station is CoMP (Coordinated MultiPoint transmission / reception) in LTE-Advanced (Long Term Evolution-Advanced) system of 3GPP (3rd Generation Partnership Project) Item 10. The communication method according to any one of Items 6 to 9.

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