JP2014168163A - Wireless base station - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the delay in the reception processing of a signal transmitted by a mobile station even when the destination wireless base station of the signal is switched to another one during "Inter-eNB CA."SOLUTION: A wireless base station eNB #11 includes a transmission unit configured to notify wireless base stations (eNB #1/eNB #12/eNB #13) of a state variable in a layer 2 to be used in communication with a mobile station UE.

Description

  The present invention relates to a radio base station.

  The radio base station eNB and the mobile station UE corresponding to the LTE (Long Term Evolution) scheme include a PHY (physical) layer, a MAC (Media Access Control) layer, an RLC (Radio Link Control) layer, and a PDCP (Packet Data Convergence). (Protocol) layer and RRC (Radio Resource Control) layer.

  The PDCP layer is configured to perform concealment processing, falsification detection processing, and header compression processing.

  Here, the COUNT value is used in the concealment process and the falsification detection process. The COUNT value is composed of HFN (Hyper Frame Number) and PDCP-SN (Sequence Number).

  The PDCP-SN is configured with 12 bits or 7 bits, and is configured to be incremented every time a packet is transmitted to the RLC by the PDCP layer.

  The HFN is composed of 20 bits or 25 bits, and is configured to be incremented every time the PDCP-SN circulates.

  If the COUNT values are not synchronized between the PDCP layer on the transmission side and the PDCP layer on the reception side, the decryption process cannot be performed correctly in the PDCP layer on the reception side.

  Specifically, the PDCP layer on the transmitting side performs concealment processing (header compression processing and tamper detection processing) on the packet (PDCP-SDU) received from the RRC layer using the COUNT value, and PDCP is applied to the header. By adding -SN, it is configured to transmit to the RLC layer as PDCP-PDU.

  On the other hand, the PDCP layer on the receiving side manages the reception window. As shown in FIG. 5, the PDCP-SN assigned to the received packet (PDCP-PDU) is a PDCP-SN outside the reception window. For example, the packet is discarded.

  If the PDCP-SN assigned to the received packet (PDCP-PDU) is the PDCP-SN within the reception window, the PDCP layer on the receiving side performs the packet deciphering process from the current reception state. An HFN to be used is estimated, and a packet (PDCP-SDU) obtained by performing a concealment process on the packet using the estimated HFN is transmitted to an upper layer, and a reception window is updated. Has been.

  The RLC layer on the transmission side and the RLC layer on the reception side are configured to perform window control in order to provide order control and duplication control.

  Here, every time a new RLC-PDU is transmitted, the RLC layer on the transmission side adds an SN (Sequence Number) and receives “Status report (ACK / NACK)” from the RLC layer on the reception side. Therefore, “Tx window” is updated.

  On the other hand, the RLC layer on the receiving side is configured to update “Rx window” when RLC-PDUs can be received in the SN order. “Rx window” is expressed by a state variable managed by the RLC layer on the receiving side.

  In addition, if the “Status report” from the RLC layer on the receiving side cannot be received, the RLC layer on the transmitting side cannot update the “Tx window”, that is, it is new due to the occurrence of “Tx window stalling”. The RLC layer on the receiving side is configured to feed back “Status report” at an appropriate frequency.

  For example, the RLC layer on the receiving side is configured to feed back “Status report” in response to a feedback request from the transmitting side or in response to detection of a missing SN in the received RLC-PDU.

  Further, in LTE Release-10, in order to realize broadband communication exceeding 20 MHz (for example, communication at 100 Hz), communication is performed by bundling a plurality of CCs (component carriers) under the same radio base station eNB. CA (Carrier Aggregation), that is, “Intra-eNB CA” has been introduced (see FIG. 6A).

  Thereafter, "Small Cell enhancement" was proposed in LTE Release 12 or later, and communication is performed by bundling CCs (cells) under different radio base stations eNB as one of more flexible network architectures than before. The introduction of “Inter-eNB CA” is under consideration (see FIG. 6B).

  For example, using “Inter-eNB CA”, for a control signal (C-plane signal) that requires reliability, cell # 1 (macro cell) subordinate to radio base station eNB # 1 via SRB (Signaling Radio Bearer) ), And uplink data (U-plane signal) necessary for broadband communication is communicated via cell # 11 (small cell) under radio base station eNB # 11 via DRB (Data Radio Bearer). Operation such as performing is also conceivable.

  Furthermore, as one of operation modes when performing “Inter-eNB CA”, as illustrated in FIG. 7, the mobile station UE performs radio signal transmission destination radio base station eNB (for example, radio communication) according to the signal type. Switching base stations eNB # 1 / eNB # 11) is being studied.

3GPP TS36.323 3GPP TS36.322 3GPP contribution R2-122651 3GPP contribution R2-130416

  However, in the existing LTE scheme, as illustrated in FIG. 8, when the mobile station UE dynamically switches the signal transmission destination radio base station eNB, the switching destination radio base station eNB A mechanism for notifying the radio base station eNB of the state variables in Layer 2 (RLC layer and PDCP layer) used in communication between the radio base station eNB that is the switching source and the mobile station UE has not been studied. .

  Therefore, in the existing LTE scheme, the radio base station eNB to be switched to does not immediately know which SN's PDU should be received, so the reception processing of the signal transmitted by the mobile station UE is delayed. There was a problem of doing.

  Therefore, the present invention has been made in view of the above-described problems, and is a case where a radio base station that is a transmission destination of a signal by a mobile station is switched when “Inter-eNB CA” is performed. Another object of the present invention is to provide a radio base station that can avoid delays in reception processing of such signals.

  The first feature of the present invention is that when a mobile station performs carrier aggregation using cells under the control of a plurality of radio base stations, it receives uplink data from the mobile station via the subordinate first cell. A radio base station in the plurality of radio base stations configured to be used for communication with the mobile station with respect to other radio base stations in the plurality of radio base stations. The gist is to include a transmission unit configured to notify a state variable in layer 2.

  As described above, according to the present invention, when “Inter-eNB CA” is performed, reception of such a signal is performed even when the radio base station to which the signal is transmitted by the mobile station is switched. A radio base station that can avoid processing delay can be provided.

1 is an overall configuration diagram of a mobile communication system according to a first embodiment of the present invention. FIG. 3 is a functional block diagram of a radio base station according to the first embodiment of the present invention. 5 is a flowchart showing an operation of the radio base station according to the first embodiment of the present invention. It is a whole block diagram of the mobile communication system which concerns on the modification 1 of this invention. It is a figure for demonstrating the conventional mobile communication system. It is a figure for demonstrating the conventional mobile communication system. It is a figure for demonstrating the conventional mobile communication system. It is a figure for demonstrating the conventional mobile communication system.

(Mobile communication system according to the first embodiment of the present invention)
With reference to FIG. 1 thru | or FIG. 3, the mobile communication system which concerns on the 1st Embodiment of this invention is demonstrated.

  In the present embodiment, an LTE mobile communication system will be described as an example. However, the present invention is not limited to such a mobile communication system, and is applicable to other mobile communication systems.

  As shown in FIG. 1, the mobile communication system according to the present embodiment includes a radio base station eNB # 1 that manages cell # 1 (not shown) and a radio base station that manages cell # 11 (not shown). eNB # 11, radio base station eNB # 12 that manages cell # 12 (not shown), and radio base station eNB # 13 that manages cell # 13 (not shown).

  Here, the cells # 11 to # 13 are small cells (phantom cells), and the cell # 1 is a macro cell. Note that the coverage areas of the cells # 11 to # 13 and the coverage area of the coverage area of the cell # 1 are arranged to overlap at least partially.

  The radio base station eNB # 1 may be referred to as a macro radio base station (Macro-eNB), and the radio base stations eNB # 11 to # 13 are small radio base stations (Small-eNB) or phantom radio bases. It may be called a station (Phantom-eNB).

  The mobile communication system according to the present embodiment is an LTE mobile communication system, and in the mobile communication system according to the present embodiment, the mobile station UE can perform “Inter-eNB CA”. It is configured.

  In the mobile communication system according to the present embodiment, the mobile station UE passes through the cell # 1 under the radio base station eNB # 1 and the cells # 11 through # 13 under the radio base stations eNB # 11 to eNB # 13. It is assumed that “Inter-eNB CA” is performed.

  Further, in the mobile communication system according to the present embodiment, as illustrated in FIG. 1, the mobile station UE performing the “Inter-eNB CA” performs the radio base station for uplink data (U-plane signal). It is assumed that it is transmitting to eNB # 11.

  Hereinafter, the configuration of the radio base station eNB according to the present embodiment will be described with reference to FIG. Here, since the configuration according to the present invention is the same in the radio base stations eNB # 1 / eNB # 11 to eNB # 13, the configuration of the radio base station eNB # 11 will be described as a representative.

  As illustrated in FIG. 2, the radio base station eNB # 11 according to the present embodiment includes a management unit 11, a reception unit 12, and a transmission unit 13.

  The management unit 11 is configured to manage state variables in layer 2 (PDCP layer and RLC layer) used in communication with the above-described mobile station UE.

  For example, the management unit 11 is configured to manage, as the state variable, an SN assigned to the PDCP-PDU in the PDCP layer, an SN assigned to the RLC-PDU in the RLC layer, and the like.

  The receiving unit 12 is configured to receive various signals from other radio base stations eNB # 1 / eNB # 12 / eNB # 13 and the mobile station UE, and the transmitting unit 13 is configured to receive other radio base stations eNB #. It is configured to transmit various signals to 1 / eNB # 12 / eNB # 13 and the mobile station UE.

  In the mobile communication system according to the present embodiment, for example, the receiving unit 12 is configured to receive uplink data from the mobile station UE.

  Moreover, the receiving part 12 may be comprised so that the signal which requests | requires notifying the above-mentioned state variable from radio base station eNB # 1 / eNB # 12 / eNB # 13 may be received.

  As illustrated in FIG. 1, the transmission unit 13 performs communication with the mobile station UE with respect to the radio base stations eNB # 1 / eNB # 12 / eNB # 13 at a predetermined timing (for example, periodically). It is configured to notify the state variable in the layer 2 being used.

  Moreover, the transmission part 13 may be comprised so that this state variable may be notified only to the radio base station eNB which can become the radio base station eNB which receives uplink data.

  That is, the transmission unit 13 is in the state described above for a radio base station eNB that cannot be a radio base station eNB that receives uplink data, for example, a radio base station eNB that manages only “DL only cell”. It may be configured not to notify the variable.

  Moreover, the transmission part 13 may be comprised so that the above-mentioned state variable may be notified with the period set with respect to radio base station eNB # 11. Note that such a period may be set for each radio base station eNB.

  Moreover, the transmission part 13 may be comprised so that the above-mentioned state variable may be notified when a predetermined event generate | occur | produces.

  For example, the transmission unit 13 may be configured to notify the state variable described above in response to a request from the radio base stations eNB # 1 / eNB # 12 / eNB # 13.

  Alternatively, the transmission unit 13 may be configured to notify the state variable described above when a predetermined number or amount of uplink data is received.

  Alternatively, the transmission unit 13 may be configured to notify the state variable described above when the reception window is updated by a predetermined amount.

  Alternatively, the transmission unit 13 may be configured to notify the state variable described above when the SN of the received PDU is about to circulate.

  Moreover, the transmission part 13 may be comprised so that the above-mentioned state variable may be notified, when missing is detected in the received uplink data.

  Here, the transmission unit 13 may be configured to notify the above-described state variable immediately when a missing is detected in the received uplink data, or the missing is detected in the received uplink data. You may be comprised so that the above-mentioned state variable may be notified after predetermined time passes since it detected.

  Furthermore, when the quality in the cell # 11 is deteriorated from a predetermined level, or in the cell under the radio base stations eNB # 1 / eNB # 12 / eNB # 13, the transmission unit 13 is improved in quality from the predetermined level. In this case, the above-described state variable may be notified.

  Hereinafter, with reference to FIG. 3, the operation example of the mobile communication system according to the present embodiment, specifically, the operation example of the radio base station eNB # 11 according to the present embodiment will be described.

  As illustrated in FIG. 3, in step S101, the radio base station eNB # 11 determines whether or not a predetermined timing for notifying the state variable in the layer 2 used in communication with the mobile station UE has arrived. To do.

  When it is determined that the predetermined timing has arrived, the operation proceeds to step S103, and when it is determined that the predetermined timing has not arrived, the operation proceeds to step S102.

  In step S102, the radio base station eNB # 11 has received from the radio base station eNB # 1 / eNB # 12 / eNB # 13 a signal requested to notify the state variable in the layer 2 described above. judge.

  If it is determined that such a signal has been received, the operation proceeds to step S103. If it is determined that such a signal has not been received, the operation ends.

  In step S103, the radio base station eNB # 11 notifies the above-described state variables to the radio base stations eNB # 1 / eNB # 12 / eNB # 13.

(Modification 1)
Hereinafter, the mobile communication system according to the first modification of the present invention will be described with reference to FIG. 4 while focusing on differences from the mobile communication system according to the first embodiment described above.

  As illustrated in FIG. 4, in the mobile communication system according to the first modification, the transmission unit 13 of the radio base station eNB # 11 transmits the radio base station eNB # 1 / eNB # 12 / eNB via “anchor node”. It is configured to notify the above-described state variable to # 13.

  Here, the “anchor node” may be a radio base station eNB having an interface with a CN (Core Network), or may be a radio base station eNB having an RRC layer function. The radio base station eNB holding a security function may be used, or a macro radio base station (Macro-eNB) may be used.

  The characteristics of the present embodiment described above may be expressed as follows.

  The first feature of the present embodiment is that when the mobile station UE performs “Inter-eNB CA (carrier aggregation using cells subordinate to a plurality of radio base stations)”, the subordinate cell # 11 (first A radio base station eNB # 11 configured to receive uplink data from the mobile station UE via a cell), the radio base stations eNB # 1 / eNB # 12 / eNB # 13 (other radio The gist of the present invention is to include a transmission unit 13 configured to notify a base station) of a state variable in layer 2 used in communication with the mobile station UE.

  According to this feature, a radio base station eNB # 11 configured to receive uplink data from the mobile station UE moves relative to the radio base stations eNB # 1 / eNB # 12 / eNB # 13. Since it is configured to notify the state variable in layer 2 used in communication with the station UE, when “Inter-eNB CA” is performed, the transmission destination of the signal by the mobile station Even when the radio base station is switched, it is possible to avoid a delay in the signal reception process.

  In the first feature of the present embodiment, the transmission unit 13 performs the above-described state with respect to the radio base stations eNB # 1 / eNB # 12 / eNB # 13 via the “anchor node (predetermined radio base station)”. It may be configured to notify the variable.

  According to this feature, even when the radio base station eNB # 11 does not have a connection with the radio base station eNB # 12 / # 13, the radio base station eNB # 12 / # 13 Thus, the above-described state variable can be notified reliably.

  In the first feature of the present embodiment, the transmission unit 13 manages only a “DL only cell (downlink dedicated cell)” among the radio base stations eNB # 1 / eNB # 12 / eNB # 13. The eNB may be configured not to notify the state variable described above.

  According to such a feature, it is possible to avoid useless use of radio resources by avoiding notification of the above-described state variable to a radio base station eNB that cannot be a radio base station eNB that receives uplink data. .

  1st characteristic of this embodiment WHEREIN: The transmission part 13 may be comprised so that the above-mentioned state variable may be notified with the period set with respect to radio base station eNB # 11.

  According to this feature, the period for notifying the state variable can be changed in consideration of the capability of the radio base station eNB # 11, the size of the cell # 11, and the like.

  1st characteristic of this embodiment WHEREIN: Even if the transmission part 13 is comprised so that the above-mentioned state variable may be notified according to the request | requirement from radio base station eNB # 1 / eNB # 12 / eNB # 13. Good.

  According to this feature, the radio base station eNB # 11 does not notify the above-described state variable unless it receives a request from the radio base station eNB # 1 / eNB # 12 / eNB # 13. 11 processing load can be reduced.

  In the first feature of the present embodiment, the transmission unit 13 may be configured to notify the state variable described above when a predetermined number or a predetermined amount of uplink data is received.

  According to this feature, the radio base station eNB # 11 is configured to notify the above-described state variable only when a predetermined number or a predetermined amount of uplink data is received. 11 processing load can be reduced.

  In the first feature of the present embodiment, the transmission unit 13 may be configured to notify the state variable described above when a loss is detected in the received uplink data.

  According to such a feature, the radio base station eNB # 11 is configured to notify the above-described state variable only after the missing is detected in the received uplink data. Processing load can be reduced.

  In the first feature of the present embodiment, the transmission unit 13 may be configured to notify the above-described state variable after a predetermined time has elapsed since a loss is detected in the received uplink data.

  According to such a feature, since the radio base station eNB # 11 is configured to notify the above-described state variable only after a predetermined time has elapsed since the absence of the detected uplink data is detected, The processing load on the base station eNB # 11 can be reduced.

  In the first feature of the present embodiment, the transmission unit 13 uses the quality in the cell under the radio base stations eNB # 1 / eNB # 12 / eNB # 13 when the quality in the cell # 11 is deteriorated below a predetermined level. May be configured to notify the above-described state variable when becomes better than a predetermined level.

  According to such a feature, the radio base station eNB # 11 has the quality in the cell under the radio base stations eNB # 1 / eNB # 12 / eNB # 13 when the quality in the cell # 11 is deteriorated below a predetermined level. Since it is configured to notify the above-described state variable only when it becomes better than a predetermined level, the processing load of the radio base station eNB # 11 can be reduced.

  Note that the operations of the mobile station UE and the radio base stations eNB # 1 / eNB # 11 to eNB # 13 described above may be performed by hardware or may be performed by a software module executed by a processor. , Or a combination of both.

  The software module includes a RAM (Random Access Memory), a flash memory, a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electronically Erasable and Programmable ROM, a hard disk, a registerable ROM, a hard disk). Alternatively, it may be provided in a storage medium of an arbitrary format such as a CD-ROM.

  Such a storage medium is connected to the processor so that the processor can read and write information from and to the storage medium. Further, such a storage medium may be integrated in the processor. Such a storage medium and processor may be provided in the ASIC. Such an ASIC may be provided in the mobile station UE or the radio base stations eNB # 1 / eNB # 11 to eNB # 13. Further, the storage medium and the processor may be provided in the mobile station UE and the radio base stations eNB # 1 / eNB # 11 to eNB # 13 as discrete components.

  Although the present invention has been described in detail using the above-described embodiments, it is obvious to those skilled in the art that the present invention is not limited to the embodiments described in this specification. The present invention can be implemented as modified and changed modes without departing from the spirit and scope of the present invention defined by the description of the scope of claims. Therefore, the description of the present specification is for illustrative purposes and does not have any limiting meaning to the present invention.

eNB # 1, eNB # 11 to eNB # 13 ... radio base station UE ... mobile station 11 ... management unit 12 ... reception unit 13 ... transmission unit

Claims (9)

The plurality configured to receive uplink data from the mobile station via the first subordinate cell when the mobile station performs carrier aggregation using cells subordinate to the plurality of radio base stations A wireless base station in a wireless base station of
A transmitter configured to notify a state variable in layer 2 used for communication with the mobile station to other wireless base stations in the plurality of wireless base stations; A featured radio base station.   The radio base station according to claim 1, wherein the transmission unit is configured to notify the other radio base station of the state variable via a predetermined radio base station.   The transmission unit is configured not to notify the state variable to a radio base station that manages only a downlink dedicated cell among the other radio base stations. Or the radio base station of 2.   4. The radio according to claim 1, wherein the transmission unit is configured to notify the state variable at a period set for the radio base station. 5. base station.   The radio base according to any one of claims 1 to 3, wherein the transmission unit is configured to notify the state variable in response to a request from the other radio base station. Bureau.   The said transmission part is comprised so that the said state variable may be notified when uplink data of the predetermined number or predetermined amount of data is received, The Claim 1 thru | or 3 characterized by the above-mentioned. The radio base station described.   4. The transmission unit according to claim 1, wherein the transmission unit is configured to notify the state variable when a loss is detected in received uplink data. 5. Radio base station.   The radio base station according to claim 7, wherein the transmitting unit is configured to notify the state variable after a predetermined time has elapsed after the missing is detected.   The transmitter notifies the state variable when the quality in the first cell is deteriorated below a predetermined level, or when the quality in the cell under the other radio base station is better than a predetermined level. The radio base station according to claim 1, wherein the radio base station is configured as described above.

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