JP2016036185A - Mobile communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile communication system capable of efficiently reducing power consumption of a network node in a local area range.SOLUTION: In a mobile communication system, a channel quality measuring unit 1212 in an HeNB 1200 measures the quality of a radio channel established between the HeNB 1200 and UE. The channel quality measuring unit 1212 determines that the UE should communicate with a base station that has established a radio channel with higher quality among a radio channel between the HeNB 1200 including the channel quality measuring unit itself and the UE, and a radio channel between another base station and the UE. If the channel quality measuring unit 1212 determines that the radio channel between the other base station and the UE is higher in quality, and determines that the UE should communicate with the other base station, a control unit 1211 performs energy saving operation at the side of the HeNB 1200 including the control unit itself.SELECTED DRAWING: Figure 14

Description

  The present invention relates to a mobile communication system that performs wireless communication between a plurality of mobile terminals and a base station.

  Among the communication systems called the third generation, the W-CDMA (Wideband Code division Multiple Access) system has been commercialized in Japan since 2001. Further, by adding a packet transmission channel (High Speed-Downlink Shared Channel: HS-DSCH) to the downlink (dedicated data channel, dedicated control channel), further speed-up of data transmission using the downlink is achieved. Realized HSDPA (High Speed Downlink Packet Access) service has been started. Furthermore, in order to further increase the speed of data transmission in the uplink direction, a service is also started for the HSUPA (High Speed Uplink Packet Access) method. W-CDMA is a communication system defined by 3GPP (3rd Generation Partnership Project), which is a standardization organization for mobile communication systems, and has compiled release 8 standards.

  Further, in 3GPP, as a communication method different from W-CDMA, a system architecture for a system configuration including a long term evolution (LTE) for a wireless section and a core network (also simply referred to as a network) is used. A new communication method called Evolution (System Architecture Evolution: SAE) is being studied.

  In LTE, an access scheme, a wireless channel configuration, and a protocol are completely different from the current W-CDMA (HSDPA / HSUPA). For example, W-CDMA uses code division multiple access (W-CDMA), whereas LTE is OFDM (Orthogonal Frequency Division Multiplexing) in the downlink direction and SC-FDMA (Single) in the uplink direction. Career Frequency Division Multiple Access) is used. The bandwidth is 5 MHz for W-CDMA, whereas the bandwidth can be selected for each base station among 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz in LTE. Also, LTE does not include circuit switching as in W-CDMA, and is only a packet communication system.

  In LTE, a communication system is configured using a new core network different from General Packet Radio Service (GPRS), which is a core network of W-CDMA. Therefore, LTE is an independent radio access network different from the W-CDMA network. Defined. Therefore, in order to distinguish from a W-CDMA communication system, in an LTE communication system, a base station (Base station) that communicates with a mobile terminal (User Equipment: UE) is called an eNB (E-UTRAN NodeB). A base station controller (Radio Network Controller) for exchanging control data and user data with a base station of this type is called an EPC (Evolved Packet Core) or aGW (Access Gateway). In the LTE communication system, a unicast service and an E-MBMS service (Evolved Multimedia Broadcast Multicast Service) are provided. The E-MBMS service is a broadcast-type multimedia service and may be simply referred to as MBMS. Mass broadcast contents such as news, weather forecasts, and mobile broadcasts are transmitted to a plurality of mobile terminals. This is also called a point-to-multipoint service.

  Non-Patent Document 1 (Chapter 4.6.1) describes the current decisions regarding the overall architecture of the LTE system in 3GPP. The overall architecture will be described with reference to FIG. FIG. 1 is an explanatory diagram illustrating a configuration of an LTE communication system. In FIG. 1, a control protocol for the mobile terminal 101 such as RRC (Radio Resource Control), a user plane such as PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), PHY (Physical layer). E-UTRAN (Evolved Universal Terrestrial Radio Access) is composed of one or a plurality of base stations 102.

  The base station 102 performs scheduling (scheduling) and transmission of a paging signal (also called a paging signal or paging message) notified from an MME (Mobility Management Entity) 103. Base stations 102 are connected to each other via an X2 interface. The base station 102 is connected to an EPC (Evolved Packet Core) through an S1 interface. More specifically, the base station 102 is connected to an MME (Mobility Management Entity) 103 via an S1_MME interface, and is connected to an S-GW (Serving Gateway) 104 via an S1_U interface.

  The MME 103 distributes the paging signal to a plurality or a single base station 102. Further, the MME 103 performs mobility control (Mobility control) in an idle state. The MME 103 manages a tracking area list when the mobile terminal is in a standby state and in an active state.

  The S-GW 104 transmits / receives user data to / from one or a plurality of base stations 102. The S-GW 104 becomes a local mobility anchor point at the time of handover between base stations. The EPC further includes a P-GW (PDN Gateway), which performs packet filtering and UE-ID address allocation for each user.

  A control protocol RRC between the mobile terminal 101 and the base station 102 performs broadcasting, paging, RRC connection management, and the like. There are RRC_IDLE and RRC_CONNECTED as states of the base station and the mobile terminal in RRC. In RRC_IDLE, PLMN (Public Land Mobile Network) selection, system information (System Information: SI) notification, paging, cell re-selection, mobility, and the like are performed. In RRC_CONNECTED, a mobile terminal has an RRC connection (connection), can transmit / receive data to / from the network, and performs handover (Handover: HO), measurement of a neighbor cell (Neighbour cell), and the like. RRC_IDLE is also simply referred to as IDLE, a wait state. RRC_CONNECTED is also simply referred to as CONNECTED or connection state.

  Current determination items regarding the frame configuration in the LTE system in 3GPP described in Non-Patent Document 1 (Chapter 5) will be described with reference to FIG. FIG. 2 is an explanatory diagram showing a configuration of a radio frame used in the LTE communication system. In FIG. 2, one radio frame is 10 ms. The radio frame is divided into ten equally sized subframes. The subframe is divided into two equally sized slots. A downlink synchronization signal (SS) is included in the first and sixth subframes for each radio frame. The synchronization signal includes a first synchronization signal (Primary Synchronization Signal: P-SS) and a second synchronization signal (Secondary Synchronization Signal: S-SS). In each subframe, multiplexing of a channel for MBSFN (Multimedia Broadcast multicast service Single Frequency Network) and a channel for other than MBSFN is performed. Hereinafter, an MBSFN transmission subframe is referred to as an MBSFN subframe.

  Non-Patent Document 2 describes a signaling example at the time of MBSFN subframe allocation. FIG. 3 is an explanatory diagram showing the configuration of the MBSFN frame. In FIG. 3, an MBSFN subframe is allocated for each MBSFN frame (MBSFN frame). A set of MBSFN frames (MBSFN frame Cluster) is scheduled. A repetition period (Repetition Period) of a set of MBSFN frames is assigned.

  Non-Patent Document 1 (Chapter 5) describes the current decisions regarding the channel configuration in the LTE system in 3GPP. In the CSG cell (Closed Subscriber Group cell), it is assumed that the same channel configuration as that of the non-CSG cell is used. The physical channel will be described with reference to FIG. FIG. 4 is an explanatory diagram illustrating physical channels used in the LTE communication system. In FIG. 4, a physical broadcast channel (PBCH) 401 is a channel for downlink transmission from the base station 102 to the mobile terminal 101. A BCH transport block is mapped to four subframes in a 40 ms interval. There is no obvious signaling of 40ms timing. A physical control format indicator channel (PCFICH) 402 is a channel for downlink transmission from the base station 102 to the mobile terminal 101. PCFICH notifies base station 102 to mobile terminal 101 about the number of OFDM symbols used for PDCCHs. PCFICH is transmitted for each subframe.

  A physical downlink control channel (PDCCH) 403 is a channel for downlink transmission from the base station 102 to the mobile terminal 101. The PDCCH includes resource allocation, HARQ (Hybrid Automatic Repeat reQuest) information on DL-SCH (a downlink shared channel that is one of the transport channels shown in FIG. 5 described later), PCH (transformer shown in FIG. 5). A paging channel which is one of the port channels). The PDCCH carries an Uplink Scheduling Grant. The PDCCH carries Ack (Acknowledgement) / Nack (Negative Acknowledgement), which is a response signal for uplink transmission. The PDCCH is also called an L1 / L2 control signal.

  A physical downlink shared channel (PDSCH) 404 is a channel for downlink transmission from the base station 102 to the mobile terminal 101. DL-SCH (downlink shared channel) that is a transport channel and PCH that is a transport channel are mapped to the PDSCH. A physical multicast channel (PMCH) 405 is a channel for downlink transmission from the base station 102 to the mobile terminal 101. A multicast channel (Multicast Channel: MCH) that is a transport channel is mapped to the PMCH.

  A physical uplink control channel (PUCCH) 406 is a channel for uplink transmission from the mobile terminal 101 to the base station 102. The PUCCH carries Ack / Nack which is a response signal (response) to downlink transmission. The PUCCH carries a CQI (Channel Quality Indicator) report. CQI is quality information indicating the quality of received data or channel quality. The PUCCH carries a scheduling request (SR). A physical uplink shared channel (PUSCH) 407 is a channel for uplink transmission from the mobile terminal 101 to the base station 102. UL-SCH (uplink shared channel which is one of the transport channels shown in FIG. 5) is mapped to PUSCH.

  A physical HARQ indicator channel (PHICH) 408 is a channel for downlink transmission from the base station 102 to the mobile terminal 101. PHICH carries Ack / Nack which is a response to uplink transmission. A physical random access channel (PRACH) 409 is a channel for uplink transmission from the mobile terminal 101 to the base station 102. The PRACH carries a random access preamble.

  The downlink reference signal (Reference signal) is a symbol known as a mobile communication system. The downlink reference signal is inserted into the first, third and last OFDM symbols of each slot. As a measurement of the physical layer of the mobile terminal, there is a reference symbol received power (RSRP) measurement.

  The transport channel described in Non-Patent Document 1 (Chapter 5) will be described with reference to FIG. FIG. 5 is an explanatory diagram for explaining a transport channel used in an LTE communication system. FIG. 5A shows the mapping between the downlink transport channel and the downlink physical channel. FIG. 5B shows mapping between the uplink transport channel and the uplink physical channel. A broadcast channel (BCH) for the downlink transport channel is broadcast to the entire coverage of the base station (cell). The BCH is mapped to the physical broadcast channel (PBCH).

  Retransmission control by HARQ (Hybrid ARQ) is applied to the downlink shared channel (DL-SCH). DL-SCH can be broadcast to the entire coverage of a base station (cell). DL-SCH supports dynamic or semi-static resource allocation. Quasi-static resource allocation is also referred to as persistent scheduling. DL-SCH supports DRX (Discontinuous reception) of a mobile terminal in order to reduce power consumption of the mobile terminal. DL-SCH is mapped to a physical downlink shared channel (PDSCH).

  The paging channel (PCH) supports DRX of the mobile terminal in order to enable low power consumption of the mobile terminal. The PCH is required to be broadcast to the entire coverage of the base station (cell). The PCH is mapped to a physical resource such as a physical downlink shared channel (PDSCH) that can be dynamically used for traffic, or a physical resource such as a physical downlink control channel (PDCCH) of another control channel. The multicast channel (MCH) is used for broadcast to the entire coverage of the base station (cell). The MCH supports SFN combining of MBMS services (MTCH and MCCH) in multi-cell transmission. The MCH supports quasi-static resource allocation. MCH is mapped to PMCH.

  Retransmission control by HARQ (Hybrid ARQ) is applied to the uplink shared channel (UL-SCH). UL-SCH supports dynamic or semi-static resource allocation. UL-SCH is mapped to a physical uplink shared channel (PUSCH). The random access channel (RACH) shown in FIG. 5B is limited to control information. RACH is at risk of collision. The RACH is mapped to a physical random access channel (PRACH).

  HARQ will be described. HARQ is a technique for improving the communication quality of a transmission path by combining automatic repeat request (ARQ) and error correction (Forward Error Correction). HARQ has an advantage that error correction functions effectively by retransmission even for a transmission path whose communication quality changes. In particular, further quality improvement can be obtained by combining the initial transmission reception result and the retransmission reception result upon retransmission.

  An example of the retransmission method will be described. When the reception side cannot decode the received data correctly, in other words, when a CRC (Cyclic Redundancy Check) error occurs (CRC = NG), “Nack” is transmitted from the reception side to the transmission side. The transmitting side that has received “Nack” retransmits the data. When the reception side can correctly decode the received data, in other words, when no CRC error occurs (CRC = OK), “Ack” is transmitted from the reception side to the transmission side. The transmitting side that has received “Ack” transmits the next data.

  An example of the HARQ method is chase combining. Chase combining is a method of transmitting the same data in initial transmission and retransmission, and is a method of improving gain by combining initial transmission data and retransmission data in retransmission. This means that even if there is an error in the initial transmission data, the data is partially accurate, and the data is transmitted with higher accuracy by combining the correct initial transmission data and the retransmission data. It is based on the idea that it can be done. Another example of the HARQ scheme is IR (Incremental Redundancy). IR is to increase redundancy, and by transmitting parity bits in retransmission, the redundancy is increased in combination with initial transmission, and the quality is improved by an error correction function.

  A logical channel (logical channel) described in Non-Patent Document 1 (Chapter 6) will be described with reference to FIG. FIG. 6 is an explanatory diagram illustrating logical channels used in the LTE communication system. FIG. 6A shows mapping between the downlink logical channel and the downlink transport channel. FIG. 6B shows mapping between the uplink logical channel and the uplink transport channel. The broadcast control channel (BCCH) is a downlink channel for broadcast system control information. The BCCH that is a logical channel is mapped to a broadcast channel (BCH) that is a transport channel or a downlink shared channel (DL-SCH).

  The paging control channel (Paging Control Channel: PCCH) is a downlink channel for transmitting a paging signal. PCCH is used when the network does not know the cell location of the mobile terminal. The PCCH that is a logical channel is mapped to a paging channel (PCH) that is a transport channel. The common control channel (CCCH) is a channel for transmission control information between the mobile terminal and the base station. CCCH is used when the mobile terminal does not have an RRC connection with the network. In the downlink direction, the CCCH is mapped to a downlink shared channel (DL-SCH) that is a transport channel. In the uplink direction, the CCCH is mapped to an uplink shared channel (UL-SCH) that is a transport channel.

  A multicast control channel (MCCH) is a downlink channel for one-to-many transmission. The MCCH is used for transmission of MBMS control information for one or several MTCHs from the network to the mobile terminal. MCCH is used only for mobile terminals that are receiving MBMS. MCCH is mapped to the downlink shared channel (DL-SCH) or multicast channel (MCH), which is a transport channel.

  The dedicated control channel (DCCH) is a channel for transmitting dedicated control information between the mobile terminal and the network. The DCCH is mapped to the uplink shared channel (UL-SCH) in the uplink, and is mapped to the downlink shared channel (DL-SCH) in the downlink.

  The dedicated traffic channel (Dedicated Traffic Channel: DTCH) is a channel for one-to-one communication to individual mobile terminals for transmitting user information. DTCH exists for both uplink and downlink. The DTCH is mapped to the uplink shared channel (UL-SCH) in the uplink, and is mapped to the downlink shared channel (DL-SCH) in the downlink.

  The multicast traffic channel (MTCH) is a downlink channel for transmitting traffic data from the network to the mobile terminal. MTCH is a channel used only for a mobile terminal that is receiving MBMS. MTCH is mapped to a downlink shared channel (DL-SCH) or a multicast channel (MCH).

  GCI is a global cell identity. In LTE and UMTS (Universal Mobile Telecommunication System), a CSG cell (Closed Subscriber Group cell) is introduced. The CSG cell will be described below (see non-patent document 3 chapter 3.1). A CSG (Closed Subscriber Group) cell is a cell in which an operator identifies an available subscriber (hereinafter may be referred to as a “specific subscriber cell”). The identified subscriber is allowed to access one or more E-UTRAN cells of the Public Land Mobile Network (PLMN). One or more E-UTRAN cells to which the identified subscribers are allowed access are referred to as “CSG cells (CSG cell (s))”. However, PLMN has access restrictions. The CSG cell is a part of a PLMN that broadcasts a unique CSG identity (CSG identity: CSG ID; CSG-ID). Members of the subscriber group who have been registered in advance and permitted access the CSG cell using the CSG-ID that is the access permission information.

  The CSG-ID is broadcast by the CSG cell or cell. There are a plurality of CSG-IDs in a mobile communication system. The CSG-ID is then used by the mobile terminal (UE) to facilitate access of CSG related members. The location tracking of a mobile terminal is performed in units of areas composed of one or more cells. The position tracking is to enable tracking of the position of the mobile terminal and calling (the mobile terminal receives a call) even in the standby state. This area for tracking the location of the mobile terminal is called a tracking area. The CSG white list is a list stored in a USIM (Universal Subscriber Identity Module) in which all CSG IDs of CSG cells to which a subscriber belongs are recorded. The CSG white list may be referred to as an allowed CSG ID list.

  A “suitable cell” will be described below (refer to Chapter 4.3 of Non-Patent Document 3). A “suitable cell” is a cell in which the UE camps on to receive normal service. Such a cell shall satisfy the following conditions:

  (1) The cell is a selected PLMN or a registered PLMN, or a part of a PLMN in an “Equivalent PLMN list”.

(2) In the latest information provided by NAS (Non-Access Stratum), the following conditions must be satisfied. (A) The cell is not a barred cell. (B) And not a part of the “Forbidden LAs” list, but a part of at least one tracking area (TA). In that case, the cell needs to satisfy the above (1). (C) The cell satisfies the cell selection evaluation criteria. (D) The cell is a CSG cell according to system information (SI). For the identified cell, the CSG-ID shall be part of the UE's “CSG WhiteList” (included in the UE's CSG WhiteList).

  An “acceptable cell” will be described below (see non-patent document 3 chapter 4.3). This is a cell where the UE camps on in order to receive a limited service (emergency call). Such a cell shall satisfy all the following requirements: That is, the minimum set of requirements for initiating an emergency call in an E-UTRAN network is shown below. (1) The cell is not a barred cell. (2) The cell satisfies the cell selection evaluation criteria.

  “Camping on a cell” means that the UE has completed cell selection or cell re-selection processing, and the UE monitors the system information and paging information. Selected state.

  In 3GPP, base stations called Home-NodeB (Home-NB; HNB) and Home-eNodeB (Home-eNB; HeNB) are being studied. The HNB in UTRAN or the HeNB in E-UTRAN is a base station for, for example, home, corporate, and commercial access services. Non-Patent Document 4 discloses three different modes of access to HeNB and HNB. Specifically, there are an open access mode, a closed access mode, and a hybrid access mode.

  Each mode has the following characteristics. In the open access mode, the HeNB or HNB is operated as a normal cell of a normal operator. In the closed access mode, the HeNB or HNB is operated as a CSG cell. This is a CSG cell accessible only to CSG members. In the hybrid access mode, a non-CSG member is a CSG cell to which access is permitted at the same time. In other words, a cell in hybrid access mode (also referred to as a hybrid cell) is a cell that supports both an open access mode and a closed access mode.

  In 3GPP, it is discussed to divide all PCIs (Physical Cell Identity) into CSG cells and non-CSG cells (referred to as PCI split) (see Non-Patent Document 5). Further, it is discussed that the PCI split information is reported from the base station to the mobile terminals being served by the system information. Non-Patent Document 5 discloses a basic operation of a mobile terminal using PCI split. A mobile terminal that does not have PCI split information needs to perform cell search using all PCIs, for example, using all 504 codes. On the other hand, a mobile terminal having PCI split information can perform a cell search using the PCI split information.

  Further, in 3GPP, as a release 10, a Long Term Evolution Advanced (LTE-A) standard is being developed (see Non-Patent Document 6 and Non-Patent Document 7).

  In the LTE-A system, in order to obtain a high communication speed, a high throughput at a cell edge, a new coverage area, and the like, it is considered to support a relay (Relay: relay node (RN)). The relay node is wirelessly connected to the radio access network via a donor cell (Donor eNB; DeNB). Within the donor cell, the network (NW) to relay link shares the same frequency band as the network to UE link. In this case, a Release 8 UE can also be connected to the donor cell. A link between the donor cell and the relay node is referred to as a backhaul link, and a link between the relay node and the UE is referred to as an access link.

  As a backhaul link multiplexing method in FDD (Frequency Division Duplex), transmission from the DeNB to the RN is performed in the downlink (DL) frequency band, and transmission from the RN to the DeNB is performed in the uplink (UL) frequency band. As a resource division method in the relay, a link from DeNB to RN and a link from RN to UE are time-division multiplexed in one frequency band, and a link from RN to DeNB and a link from UE to RN are also one frequency band. Is time-division multiplexed. By doing so, it is possible to prevent the relay transmission from interfering with the reception of the own relay in the relay.

  Heterogeneous networks (HetNets) has been added as one of the technologies studied in LTE-A. In 3GPP, low output power local area range network nodes such as pico eNB (pico cell), hot zone cell node, HeNB / HNB / CSG cell, relay node, remote radio head (RRH) It has been decided to handle.

  In 3GPP, discussions have been made on energy saving in infrastructure. The current discussion on reducing power consumption of infrastructure is as follows. A base station or cell employed as a capacity booster monitors the traffic load and switches off if the traffic stays below a certain threshold for a certain period of time. Yes (see Non-Patent Document 8). When the load is high in the operating base station, the base station can request the switched-on base station to switch on (see Non-Patent Document 8). The base station that can be switched off is a cell that provides basic coverage and basic capacity (see Non-Patent Document 9).

  In general, cells that provide basic coverage and basic capacity are considered wide-area eNBs (see Non-Patent Document 10). From this, it can be considered that the network node in the local area range is not considered in the technique disclosed in Non-Patent Document 8. Therefore, the technique disclosed in Non-Patent Document 8 has a problem that low power consumption cannot be realized in a network node in the local area range.

  A technique relating to low power consumption in a network node in the local area range is disclosed in Patent Document 1. In the technique disclosed in Patent Literature 1, in a wireless communication system including a femto base station such as a Home-eNB, the base station is connected to the base station from the network side according to the location status of the mobile terminal in the cell formed by the base station. By giving a control signal via the S1 interface or the like, the radio signal output of the femto base station is stopped or started.

JP 2009-159355 A

3GPP TS36.300 V9.1.0 Chapter 4.6.1, Chapter 4.6.2, Chapter 5, Chapter 6, 10.7 3GPP R1-072963 3GPP TS36.304 V9.0.0 Chapter 3.1, 4.3, Chapter 5.2.4 3GPP S1-083461 3GPP R2-082899 3GPP TR 36.814 V1.1.1 3GPP TR 36.912 V9.0.0 3GPP R3-093104 3GPP R3-093103 3GPP RP-090665

  Efficiently reducing the power consumption of network nodes in the local area range is an important issue in promoting the reduction of power consumption of the system.

  As described above, in the wireless communication system disclosed in Patent Document 1, the radio signal output of the femto base station is controlled by an instruction from the network side, which increases the load on the network side.

  Further, in the wireless communication system disclosed in Patent Literature 1, the radio signal output of the femto base station is controlled according to the location status of the mobile terminal, but due to factors other than the location status of the mobile terminal, the femto base Sometimes it is better to restrict the operation of network nodes such as stations. For example, when a device on the backhaul side cannot be connected to the network node due to a failure or the like, the network node cannot normally communicate with the mobile terminal even if the power is on. In such a case, turning on the power supply of the network node causes wasteful power consumption. In such a case, limiting the operation of the network node is not disclosed in Patent Document 1.

  As described above, the conventional technology cannot efficiently reduce the power consumption of the network node in the local area range.

  An object of the present invention is to provide a mobile communication system capable of efficiently reducing power consumption in a network node in a local area range.

  The mobile communication system of the present invention includes a mobile terminal device, a base station device capable of wireless communication with the mobile terminal device, another base station device capable of wireless communication with the mobile terminal device, the base station device, and the A mobile communication system comprising a core network to which another base station apparatus is connected so as to be capable of wired communication, the quality of a radio channel established between the base station apparatus and the mobile terminal apparatus, and the other Channel quality comparing means for comparing the quality of another radio channel established between the base station apparatus and the mobile terminal apparatus, and the base station apparatus transmits a downlink transmission signal to be transmitted to the mobile terminal apparatus From the normal operation state in which the transmission operation of the mobile terminal apparatus and the reception operation of the uplink transmission signal transmitted from the mobile terminal apparatus are shifted to the low power operation state in which the transmission operation and the reception operation are stopped, When the line quality comparison unit determines that the quality of the other radio channel is higher than the quality of the radio channel and the other radio channel, the line quality comparison unit shifts to the base station apparatus to the low power operation state. It is characterized by instructing as follows.

  According to the mobile communication system of the present invention, a mobile communication system includes a mobile terminal device, a base station device, another base station device, and a core network. The mobile communication system includes a line quality comparison unit. By this channel quality comparison means, the quality of the radio channel established between the base station device and the mobile terminal device and the quality of the other radio channel established between the other base station device and the mobile terminal device Are compared. When the channel quality comparison unit determines that the quality of the other radio channel is higher, the base station apparatus is shifted from the normal operation state to the low power operation state according to the instruction of the channel quality comparison unit. For example, the quality of the backhaul connecting the base station device and the core network is degraded, the quality of the radio channel established between the base station device and the mobile terminal device is degraded, and the other base station device and the mobile terminal When the quality of the other radio link established with the apparatus becomes higher, the base station apparatus is shifted from the normal operation state to the low power consumption state. As a result, the user of the mobile terminal apparatus can be prompted to communicate with another base station apparatus, so that the possibility of the user of the mobile terminal apparatus receiving the disadvantages due to the deterioration of the quality of the radio channel is reduced. Can do.

  In addition, the base station device is operated in a normal operation state when a higher-quality wireless channel can be established with the mobile terminal device than other base station devices, and the lower-quality wireless channel. Is established, a low power operating state is entered. As a result, power consumption can be reduced compared to the case where the base station apparatus is always operated in the normal operation state. Therefore, it is possible to efficiently reduce the power consumption in the base station apparatus that is a network node in the local area range.

  The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

It is explanatory drawing which shows the structure of the communication system of a LTE system. FIG. 2 is an explanatory diagram showing a configuration of a radio frame used in an LTE communication system. It is explanatory drawing which shows the structure of a MBSFN frame. It is explanatory drawing explaining the physical channel used with the communication system of a LTE system. It is explanatory drawing explaining the transport channel used with the communication system of a LTE system. It is explanatory drawing explaining the logical channel used with the communication system of a LTE system. It is a block diagram which shows the whole structure of the mobile communication system of the LTE system currently discussed in 3GPP. It is a block diagram which shows the structure of the mobile terminal (mobile terminal 71 of FIG. 7) which concerns on this invention. It is a block diagram which shows the structure of the base station (base station 72 of FIG. 7) based on this invention. It is a block diagram which shows the structure of MME which concerns on this invention (MME part 73 of FIG. 7). It is a block diagram which shows the structure of HeNBGW74 shown in FIG. 7 which is HeNBGW which concerns on this invention. 5 is a flowchart illustrating an outline from a cell search to a standby operation performed by a mobile terminal (UE) in an LTE communication system. It is a block diagram which shows the structure of the mobile communication system 600 of Embodiment 1 of this invention. It is a block diagram which shows the structure of HeNB1200 of Embodiment 2 of this invention. It is a block diagram which shows the structure of HeNB of Embodiment 3 of this invention. It is a block diagram which shows the structure of HeNB of Embodiment 3 of this invention. It is a block diagram which shows the structure of HeNB1300 of Embodiment 4 of this invention. It is a figure which shows frequency scheduling. It is a figure which shows the example of one subcarrier. It is a figure which shows the subcarrier which comprises a frequency band. FIG. 19 is a diagram showing frequency scheduling and subcarriers when a band limiting method for eliminating one of the bands A and B shown in FIG. 18 is used. FIG. 19 is a diagram showing frequency scheduling and subcarriers when the method of reducing the bandwidths of two bands A and B shown in FIG. 18 is used. It is a figure which shows the frequency scheduling at the time of using the band-limiting method which loses data transmission alternately for every subcarrier, and a subcarrier.

Embodiment 1 FIG.
FIG. 7 is a block diagram showing the overall configuration of an LTE mobile communication system currently under discussion in 3GPP. Currently, in 3GPP, CSG (Closed Subscriber Group) cells (E-UTRAN Home-eNodeB (Home-eNB; HeNB), UTRAN Home-NB (HNB)) and non-CSG cells (E-UTRAN eNodeB ( eNB), UTRAN NodeB (NB), GERAN BSS) and the like, and the configuration shown in FIG. 7 is proposed for E-UTRAN (non-patent document). Reference 1 see Chapter 4.6.1.).

  FIG. 7 will be described. A mobile terminal device (hereinafter referred to as “user equipment (UE)”) 71 is capable of wireless communication with a base station device (hereinafter referred to as “base station”) 72, and transmits and receives signals by wireless communication. The base station 72 is classified into an eNB 72-1 and a Home-eNB 72-2. The eNB 72-1 is connected to the MME, S-GW, or the MME / S-GW unit (hereinafter referred to as “MME unit”) 73 including the MME and the S-GW via the S1 interface. Control information is communicated between the two. A plurality of MME units 73 may be connected to one eNB 72-1. The eNBs 72-1 are connected by the X2 interface, and control information is communicated between the eNBs 72-1.

  The Home-eNB 72-2 is connected to the MME unit 73 through the S1 interface, and control information is communicated between the Home-eNB 72-2 and the MME unit 73. A plurality of Home-eNBs 72-2 are connected to one MME unit 73. Alternatively, the Home-eNB 72-2 is connected to the MME unit 73 via a HeNBGW (Home-eNB GateWay) 74. The Home-eNB 72-2 and the HeNBGW 74 are connected via the S1 interface, and the HeNBGW 74 and the MME unit 73 are connected via the S1 interface. One or a plurality of Home-eNBs 72-2 are connected to one HeNBGW 74, and information is communicated through the S1 interface. The HeNBGW 74 is connected to one or a plurality of MME units 73, and information is communicated through the S1 interface.

  Furthermore, the following configurations are currently being studied in 3GPP. The X2 interface between Home-eNB 72-2 is not supported. From the MME unit 73, the HeNBGW 74 appears as an eNB 72-1. From the Home-eNB 72-2, the HeNBGW 74 appears as the MME unit 73. Regardless of whether the Home-eNB 72-2 is connected to the MME unit 73 via the HeNBGW 74, the interface between the Home-eNB 72-2 and the MME unit 73 is the same in the S1 interface. The HeNBGW 74 does not support mobility to the Home-eNB 72-2 or mobility from the Home-eNB 72-2 that spans a plurality of MME units 73. Home-eNB 72-2 supports only one cell.

  FIG. 8 is a block diagram showing a configuration of a mobile terminal (mobile terminal 71 in FIG. 7) according to the present invention. A transmission process of the mobile terminal 71 shown in FIG. 8 will be described. First, control data from the protocol processing unit 801 and user data from the application unit 802 are stored in the transmission data buffer unit 803. The data stored in the transmission data buffer unit 803 is transferred to the encoder unit 804 and subjected to encoding processing such as error correction. There may exist data directly output from the transmission data buffer unit 803 to the modulation unit 805 without performing the encoding process. The data encoded by the encoder unit 804 is modulated by the modulation unit 805. The modulated data is converted into a baseband signal, and then output to the frequency conversion unit 806, where it is converted into a radio transmission frequency. Thereafter, a transmission signal is transmitted from the antenna 807 to the base station 72.

  Moreover, the reception process of the mobile terminal 71 is performed as follows. A radio signal from the base station 72 is received by the antenna 807. The reception signal is converted from a radio reception frequency to a baseband signal by the frequency conversion unit 806, and demodulated by the demodulation unit 808. The demodulated data is passed to the decoder unit 809 and subjected to decoding processing such as error correction. Of the decoded data, control data is passed to the protocol processing unit 801, and user data is passed to the application unit 802. A series of processing of the mobile terminal 71 is controlled by the control unit 810. Therefore, the control unit 810 is connected to each unit 801 to 809, which is omitted in FIG.

  FIG. 9 is a block diagram showing the configuration of the base station (base station 72 of FIG. 7) according to the present invention. The transmission process of the base station 72 shown in FIG. 9 will be described. The EPC communication unit 901 transmits and receives data between the base station 72 and the EPC (including the MME unit 73, the HeNBGW 74, and the like) that is a core network. The other base station communication unit 902 transmits / receives data to / from other base stations. Since the X2 interface between the Home-eNB 72-2 is a direction that is not supported, the Home-eNB 72-2 may not include the other base station communication unit 902. The EPC communication unit 901 and the other base station communication unit 902 exchange information with the protocol processing unit 903, respectively. Control data from the protocol processing unit 903 and user data and control data from the EPC communication unit 901 and the other base station communication unit 902 are stored in the transmission data buffer unit 904.

  Data stored in the transmission data buffer unit 904 is transferred to the encoder unit 905 and subjected to encoding processing such as error correction. There may exist data that is directly output from the transmission data buffer unit 904 to the modulation unit 906 without performing the encoding process. The encoded data is subjected to modulation processing by the modulation unit 906. The modulated data is converted into a baseband signal, and then output to the frequency conversion unit 907 to be converted into a radio transmission frequency. Thereafter, a transmission signal is transmitted from the antenna 908 to one or a plurality of mobile terminals 71.

  Moreover, the reception process of the base station 72 is performed as follows. Radio signals from one or a plurality of mobile terminals 71 are received by the antenna 908. The reception signal is converted from a radio reception frequency to a baseband signal by the frequency conversion unit 907, and demodulated by the demodulation unit 909. The demodulated data is transferred to the decoder unit 910 and subjected to decoding processing such as error correction. Of the decoded data, the control data is passed to the protocol processing unit 903 or the EPC communication unit 901 and the other base station communication unit 902, and the user data is passed to the EPC communication unit 901 and the other base station communication unit 902. A series of processing of the base station 72 is controlled by the control unit 911. Therefore, the control unit 911 is connected to the units 901 to 910, which is omitted in FIG.

  The function of Home-eNB 72-2 currently being discussed in 3GPP is shown below (refer to Chapter 4.6.2 of Non-Patent Document 1). Home-eNB 72-2 has the same function as eNB 72-1. In addition, when connecting with HeNBGW74, Home-eNB 72-2 has a function which discovers suitable serving HeNBGW74. The Home-eNB 72-2 is only connected to one HeNBGW 74. That is, in the case of connection with the HeNBGW 74, the Home-eNB 72-2 does not use the Flex function in the S1 interface. When Home-eNB 72-2 is connected to one HeNBGW 74, it does not connect to another HeNBGW 74 or another MME unit 73 at the same time.

  The TAC and PLMN ID of the Home-eNB 72-2 are supported by the HeNBGW 74. When the Home-eNB 72-2 is connected to the HeNBGW 74, the selection of the MME unit 73 in “UE attachment” is performed by the HeNBGW 74 instead of the Home-eNB 72-2. Home-eNB 72-2 may be deployed without network planning. In this case, the Home-eNB 72-2 is moved from one geographical area to another. Therefore, the Home-eNB 72-2 in this case needs to be connected to different HeNBGW 74 depending on the position.

  FIG. 10 is a block diagram showing the configuration of the MME (MME unit 73 in FIG. 7) according to the present invention. The PDN GW communication unit 1001 transmits and receives data between the MME unit 73 and the PDN GW. The base station communication unit 1002 performs data transmission / reception between the MME unit 73 and the base station 72 through the S1 interface. When the data received from the PDN GW is user data, the user data is passed from the PDN GW communication unit 1001 to the base station communication unit 1002 via the user plane communication unit 1003 and to one or a plurality of base stations 72. Sent. When the data received from the base station 72 is user data, the user data is passed from the base station communication unit 1002 to the PDN GW communication unit 1001 via the user plane communication unit 1003 and transmitted to the PDN GW.

  When the data received from the PDN GW is control data, the control data is transferred from the PDN GW communication unit 1001 to the control plane control unit 1005. When the data received from the base station 72 is control data, the control data is transferred from the base station communication unit 1002 to the control plane control unit 1005.

  The HeNBGW communication unit 1004 is provided when the HeNBGW 74 exists, and performs data transmission / reception through an interface (IF) between the MME unit 73 and the HeNBGW 74 according to the information type. The control data received from the HeNBGW communication unit 1004 is passed from the HeNBGW communication unit 1004 to the control plane control unit 1005. The result of the process in the control plane control unit 1005 is transmitted to the PDN GW via the PDN GW communication unit 1001. Further, the result processed by the control plane control unit 1005 is transmitted to one or a plurality of base stations 72 via the S1 interface via the base station communication unit 1002, and to one or a plurality of HeNBGWs 74 via the HeNBGW communication unit 1004. Sent.

  The control plane control unit 1005 includes a NAS security unit 1005-1, an SAE bearer control unit 1005-2, an idle state mobility management unit 1005-3, and the like, and performs overall processing for the control plane. The NAS security unit 1005-1 performs security of a NAS (Non-Access Stratum) message. The SAE bearer control unit 1005-2 manages the SAE (System Architecture Evolution) bearer. The idle state mobility management unit 1005-3 manages mobility in a standby state (LTE-IDLE state, also simply referred to as idle), generation and control of a paging signal in the standby state, and one or more mobile terminals 71 being served thereby Tracking area (TA) addition, deletion, update, search, tracking area list (TA List) management, etc.

  The MME unit 73 starts a paging protocol by transmitting a paging message to a cell belonging to a tracking area (Tracking Area: TA) in which the UE is registered. The idle state mobility management unit 1005-3 may perform CSG management, CSG-ID management, and white list management of the Home-eNB 72-2 connected to the MME unit 73.

  In the management of CSG-ID, the relationship between the mobile terminal corresponding to the CSG-ID and the CSG cell is managed (added, deleted, updated, searched). For example, it may be a relationship between one or a plurality of mobile terminals registered for user access with a certain CSG-ID and a CSG cell belonging to the CSG-ID. In white list management, the relationship between a mobile terminal and a CSG-ID is managed (added, deleted, updated, searched). For example, one or a plurality of CSG-IDs registered by a certain mobile terminal as a user may be stored in the white list. Management related to these CSGs may be performed in other parts of the MME unit 73. A series of processing of the MME unit 73 is controlled by the control unit 1006. Therefore, the control unit 1006 is connected to the respective units 1001 to 1005 although omitted in FIG.

  The functions of the MME currently being discussed in 3GPP are shown below (see Chapter 4.6.2 of Non-Patent Document 1). The MME performs access control for one or a plurality of mobile terminals of a CSG (Closed Subscriber Group). The MME recognizes the execution of paging optimization as an option.

  FIG. 11 is a block diagram showing a configuration of the HeNBGW 74 shown in FIG. 7 which is the HeNBGW according to the present invention. The EPC communication unit 1101 performs data transmission / reception between the HeNBGW 74 and the MME unit 73 through the S1 interface. The base station communication unit 1102 performs data transmission / reception between the HeNBGW 74 and the Home-eNB 72-2 using the S1 interface. The location processing unit 1103 performs processing for transmitting registration information and the like among the data from the MME unit 73 passed via the EPC communication unit 1101 to the plurality of Home-eNBs 72-2. The data processed by the location processing unit 1103 is transferred to the base station communication unit 1102 and transmitted to one or more Home-eNBs 72-2 via the S1 interface.

  Data that does not require processing in the location processing unit 1103 and is simply passed (transmitted) is passed from the EPC communication unit 1101 to the base station communication unit 1102 and is sent to one or a plurality of Home-eNBs 72-2 via the S1 interface. Sent. A series of processing of the HeNBGW 74 is controlled by the control unit 1104. Therefore, the control unit 1104 is connected to each of the units 1101 to 1103, which is omitted in FIG.

  The functions of the HeNBGW 74 currently being discussed in 3GPP are shown below (see Chapter 4.6.2 of Non-Patent Document 1). The HeNBGW 74 relays for the S1 application. Although part of the procedure of the MME unit 73 to the Home-eNB 72-2, the HeNBGW 74 terminates the S1 application not related to the mobile terminal 71. When the HeNBGW 74 is arranged, procedures unrelated to the mobile terminal 71 are communicated between the Home-eNB 72-2 and the HeNBGW 74, and between the HeNBGW 74 and the MME unit 73. The X2 interface is not set between the HeNBGW 74 and other nodes. The HeNBGW 74 recognizes execution of paging optimization as an option.

  Next, an example of a general cell search method in a mobile communication system will be shown. FIG. 12 is a flowchart showing an outline from a cell search to a standby operation performed by a mobile terminal (UE) in an LTE communication system. When starting the cell search, the mobile terminal uses the first synchronization signal (P-SS) and the second synchronization signal (S-SS) transmitted from the neighboring base stations in step ST1201 to generate the slot timing, the frame, Synchronize timing. A synchronization code corresponding to one-to-one PCI (Physical Cell Identity) assigned to each cell is assigned to the synchronization signal (SS) by combining P-SS and S-SS. Currently, 504 PCIs are being studied, and the 504 PCIs are used for synchronization, and the PCI of the synchronized cell is detected (specified).

  Next, for a synchronized cell, in step ST1202, a reference signal RS (Reference Signal) transmitted from the base station for each cell is detected, and the received power is measured. The reference signal RS uses a code corresponding to the PCI one-to-one, and can be separated from other cells by taking a correlation with the code. By deriving the RS code of the cell from the PCI specified in step ST1201, it is possible to detect the RS and measure the RS received power.

  Next, in step ST1203, the cell having the best RS reception quality, for example, the cell having the highest RS reception power, that is, the best cell is selected from one or more cells detected up to step ST1202.

  Next, in step ST1204, the PBCH of the best cell is received, and BCCH that is broadcast information is obtained. A MIB (Master Information Block) including cell configuration information is carried on the BCCH on the PBCH. Therefore, the MIB is obtained by receiving the PBCH and obtaining the BCCH. The MIB information includes, for example, DL (downlink) system bandwidth (also called transmission bandwidth configuration (dl-bandwidth)), the number of transmission antennas, SFN (System Frame Number), and the like.

  Next, in step ST1205, DL-SCH of the cell is received based on the MIB cell configuration information, and SIB (System Information Block) 1 in broadcast information BCCH is obtained. SIB1 includes information related to access to the cell, information related to cell selection, and scheduling information of other SIBs (SIBk; an integer of k ≧ 2). The SIB1 includes a TAC (Tracking Area Code).

  Next, in step ST1206, the mobile terminal compares the TAC of SIB1 received in step ST1205 with the TAC already held by the mobile terminal. If the result of the comparison is the same, a standby operation is started in the cell. If they are different from each other, the mobile terminal requests a change of TA in order to perform TAU (Tracking Area Update) to the core network (Core Network, EPC) (including MME) through the cell. The core network updates the TA based on the identification number (UE-ID or the like) of the mobile terminal sent from the mobile terminal together with the TAU request signal. After updating the TA, the core network transmits a TAU receipt signal to the mobile terminal. The mobile terminal rewrites (updates) the TAC (or TAC list) held by the mobile terminal with the TAC of the cell. Thereafter, the mobile terminal enters a standby operation in the cell.

  In LTE and UMTS (Universal Mobile Telecommunication System), introduction of a CSG (Closed Subscriber Group) cell is being studied. As described above, access is permitted only to one or a plurality of mobile terminals registered in the CSG cell. A CSG cell and one or more registered mobile terminals constitute one CSG. A unique identification number called CSG-ID is attached to the CSG configured in this way. A single CSG may have a plurality of CSG cells. If a mobile terminal registers in any one CSG cell, it can access another CSG cell to which the CSG cell belongs.

  In addition, Home-eNB in LTE and Home-NB in UMTS may be used as a CSG cell. The mobile terminal registered in the CSG cell has a white list. Specifically, the white list is stored in a SIM (Subscriber Identity Module) / USIM. The white list stores CSG information of CSG cells registered by the mobile terminal. Specifically, CSG-ID, TAI (Tracking Area Identity), TAC, etc. can be considered as CSG information. If the CSG-ID and the TAC are associated with each other, either one is sufficient. Further, GCI may be used as long as CSG-ID and TAC are associated with GCI (Global Cell Identity).

  From the above, a mobile terminal that does not have a white list (including the case where the white list is empty in the present invention) cannot access a CSG cell, and only accesses a non-CSG cell. Can not. On the other hand, a mobile terminal having a white list can access both a registered CSG-ID CSG cell and a non-CSG cell.

  In 3GPP, it is discussed to divide all PCIs (Physical Cell Identity) into CSG cells and non-CSG cells (referred to as PCI split) (see Non-Patent Document 5). Further, it is discussed that the PCI split information is reported from the base station to the mobile terminals being served by the system information. Non-Patent Document 5 discloses a basic operation of a mobile terminal using PCI split. A mobile terminal that does not have PCI split information needs to perform cell search using all PCIs, for example, using all 504 codes. On the other hand, a mobile terminal having PCI split information can perform a cell search using the PCI split information.

  In 3GPP, it is determined that the PCI for the hybrid cell is not included in the PCI range for the CSG cell (see Non-Patent Document 1 Chapter 10.7).

  HeNB and HNB are required to deal with various services. For example, an operator increases a radio resource that can be used by a mobile terminal by allowing the mobile terminal to be registered in a certain HeNB and HNB and allowing only the registered mobile terminal to access the HeNB and HNB cells. To enable high-speed communication. Accordingly, the service is such that the operator sets the charging fee higher than usual.

  In order to realize such a service, a CSG cell (Closed Subscriber Group cell) that can be accessed only by registered (subscribed, member) mobile terminals has been introduced. Many CSG cells (Closed Subscriber Group cells) are required to be installed in shopping streets, condominiums, schools, companies, and the like. For example, a CSG cell is installed for each store in a shopping street, each room in a condominium, each classroom in a school, and each section in a company, and only a user registered in each CSG cell can use the CSG cell. Is required. HeNB / HNB is required not only to complement communication outside the coverage of the macro cell, but also to support various services as described above. For this reason, a case where the HeNB / HNB is installed in the coverage of the macro cell may occur.

  Heterogeneous networks (HetNets) has been added as one of the technologies studied in LTE-A. In 3GPP, a low-output-power local area range (Local-area) such as a pico eNB (pico cell), a node for a hot zone cell, a HeNB / HNB / CSG cell, a relay node, or a remote radio head (RRH). range network nodes (local area range node, local area node, local node). Therefore, it is required to operate a network in which one or more such local area range nodes are incorporated in a normal eNB (macro cell). A network in which one or more local area range nodes are incorporated in a normal eNB (macro cell) is called heterogeneous networks, and an interference reduction method, a capacity improvement method, and the like are studied.

  Currently, in 3GPP, there is a discussion about energy saving in infrastructure. Specifically, the following discussions have been made. A base station or cell employed as a capacity booster monitors the traffic load and switches off if the traffic stays below a certain threshold for a certain period of time. Yes (see Non-Patent Document 8). When the load is high in the operating base station, the base station can request the base station switched off to switch on (see Non-Patent Document 8). The base station that can be switched off is a cell that provides basic coverage and basic capacity (see Non-Patent Document 9).

  The problem to be solved in the first embodiment will be described below. As described above, the technique disclosed in Non-Patent Document 8 considers a cell that provides basic coverage and basic capacity. Cells that provide basic coverage and basic capacity are considered wide-area eNBs (see Non-Patent Document 10). From this, it can be considered that the network node in the local area range is not considered in the technique disclosed in Non-Patent Document 8.

  Hereinafter, for convenience, the network node in the local area range is referred to as a local eNB (Local eNB). Moreover, a normal eNB (macro cell) can be considered as a representative example of the wide area eNB. The local eNB has a relatively small output power. A wide area eNB, for example, a normal eNB (macro cell), has a relatively large output power. In other words, the output power of the local eNB is smaller than the output power of the wide area eNB.

  Non-Patent Document 8 stipulates that power consumption can be reduced using an X2 interface. On the other hand, as described above, the HeNB, which is one of the local eNBs, does not support the X2 interface (see Chapter 4.6.1 in Non-Patent Document 1). Therefore, in HeNB, reduction of power consumption cannot be realized by the method disclosed in Non-Patent Document 8.

  As described above, the technique disclosed in Non-Patent Document 8 has a problem that low power consumption cannot be realized in the network node in the local area range.

  A technique related to low power consumption in a network node in the local area range is disclosed in Patent Document 1 described above. In the technique disclosed in Patent Literature 1, in a wireless communication system including a femto base station such as a Home-eNB, the base station is connected to the base station from the network side according to the location status of the mobile terminal in the cell formed by the base station. By giving a control signal via the S1 interface or the like, the radio signal output of the femto base station is stopped or started. In this way, when the radio signal output of the femto base station is controlled by an instruction from the network side, the load on the network side increases.

  Further, in the wireless communication system disclosed in Patent Literature 1, the radio signal output of the femto base station is controlled according to the location status of the mobile terminal, but due to factors other than the location status of the mobile terminal, the femto base Sometimes it is better to restrict the operation of network nodes such as stations.

  For example, if a device on the backhaul side of the HeNB cannot connect to the HeNB due to a failure or the like, the HeNB cannot operate normally. In this case, even if the power supply of the HeNB is turned on (On), communication with the UE is not normally performed. Therefore, if the power supply of the HeNB is turned on, power consumption is wasted. .

  A technique for solving this problem is not disclosed in Patent Document 1. As described above, the conventional technology cannot efficiently reduce the power consumption of the network node in the local area range.

  A solution in the first embodiment for solving the above problem will be described below. In the present embodiment, when the connection between the HeNB and the backhaul is disconnected, the HeNB is shifted from a normal operation to an operation for reducing power consumption. The operation for reducing power consumption is referred to as a low power operation or an energy saving operation, and this operation state is referred to as a low power operation state. The normal operation is referred to as a normal operation or a normal operation, and this operation state is referred to as a normal operation state.

  FIG. 13 is a block diagram showing a configuration of mobile communication system 600 according to Embodiment 1 of the present invention. The mobile communication system 600 has a configuration in which transmission / reception is turned off (OFF) and wired-side intermittent operation is realized as a configuration of the energy saving operation of the HeNB 606. “Transmission / reception off” means that the HeNB 606 stops the transmission operation of the downlink transmission signal that is a signal to be transmitted to the UE and the reception operation of the uplink transmission signal that is a signal transmitted from the UE.

  The mobile communication system 600 includes an EPC 601 that is a core network including an MME (Mobility Management Entity) and an S-GW (Serving Gateway), a HeNB-GW (Gateway) 602, and a BB (Broadband) access network (hereinafter referred to as “IP ( Internet Protocol) network ”603) and a femto base station apparatus 604. The femto base station apparatus 604 includes an optical line termination apparatus 605 and a HeNB 606. The optical line termination device 605 may not exist in the femto base station device 604. In this case, the femto base station apparatus 604 may be referred to as HeNB. The EPC 601 has the same configuration as the MME unit 73 shown in FIGS. 7 and 10 described above. The HeNB-GW 602 has the same configuration as the HeNBGW 74 shown in FIGS. 7 and 11 described above. The HeNB 606 has the same configuration as the base station 72 shown in FIGS. 7 and 9 described above.

  The EPC 601 is connected to the HeNB-GW 602. The HeNB-GW 602 connects the EPC 601 and the femto base station apparatus 604 via the IP network 603. As shown in FIG. 7, there are cases where the HeNB-GW 602 is not used in the LTE mobile communication system currently being discussed in 3GPP. This Embodiment is applicable even when HeNB-GW602 does not exist. The femto base station device 604 is installed in a home, for example. The HeNB 606 of the femto base station apparatus 604 is connected to the IP network 603 via the optical line termination apparatus 605. In this way, the HeNB 606 is connected to the EPC 601 so that wired communication is possible.

  The mobile communication system 600 is configured to be able to detect whether or not the connection between the HeNB 606 and the backhaul has been disconnected. Here, “backhaul” refers to a transmission path from the base station to the core network. In the present embodiment, a transmission path from HeNB 606 as a base station to EPC 601 as a core network, specifically, an optical line termination unit 605a, an IP network 603 and a HeNB-GW 602, and a line connecting them are provided. This is called “backhaul”. The backhaul corresponds to a connection device, and connects the HeNB 606 and the EPC 601 so that wired communication is possible.

  Specifically, the optical line termination device 605 includes an optical line termination unit 605a and a connection disconnection detection unit 605b. The connection disconnection detection unit 605b detects whether or not the connection between the HeNB 606 and the backhaul has been disconnected. The connection disconnection detection unit 605b corresponds to connection disconnection detection means. The optical line termination unit 605a is connected to the HeNB 606. The optical line termination device 605 is connected to the HeNB 606 by the optical line termination unit 605a. The disconnection detection unit 605b may be included in the HeNB 606 instead of the optical line termination device 605.

  When the connection between the HeNB 606 and the backhaul is disconnected, for example, when the optical line termination unit 605a becomes inoperable, the connection disconnection detection unit 605b detects that the connection with the backhaul has been disconnected. When the connection disconnection detection unit 605b detects that the connection with the backhaul has been disconnected, the connection disconnection detection unit 605b transmits the control signal to the HeNB 606 to shift the HeNB 606 from the normal operation to the energy saving operation. In this embodiment, as the energy saving operation, transmission / reception is turned off (OFF) and the wire side intermittent operation is performed. Specifically, the transmission / reception operation with the UE is turned off, and the communication with the HeNB-GW 602 via the wired side, that is, the IP network 603 and the optical network unit 605 is set to an intermittent operation. As a specific method for turning off the transmission / reception operation with the UE, the supply of the clock signal to the modulation unit may be stopped, or the supply of power to the transmission amplifier may be stopped.

  Two specific examples of a method for detecting the disconnection from the backhaul are disclosed below. (1) When the connection disconnection detection unit 605b does not receive a response signal from the HeNB-GW 602 or the EPC 601 for a certain period of time, the connection disconnection detection unit 605b determines that the connection with the backhaul has been disconnected. (2) When the connection disconnection detection unit 605b does not receive data (user data, control data) from the HeNB-GW 602 or the EPC 601 for a certain period of time, the connection disconnection detection unit 605b determines that the connection with the backhaul has been disconnected. .

  Five specific examples of the control signal notified from the connection disconnection detection unit 605b to the HeNB 606 are disclosed below. (1) Information on whether or not the connection with the backhaul has been disconnected. (2) Information indicating that the connection with the backhaul has been disconnected. (3) Information indicating that the connection with the backhaul has not been disconnected. (4) Instruction information for transition to the energy saving operation. (5) Transition permission information for energy saving operation.

  When the connection with the backhaul is recovered, the connection disconnection detection unit 605b detects that the connection with the backhaul has been recovered. When the connection disconnection detection unit 605b detects that the connection with the backhaul has been recovered, the connection disconnection detection unit 605b transmits a control signal to the HeNB 606, and shifts the HeNB 606 from the energy saving operation to the normal operation. When shifting to the normal operation, the transmission / reception operation with the UE is turned on, and the wired side is set to the continuous operation. As a specific method for turning on / off the transmission / reception operation with the UE, when the supply of the clock signal to the modulation unit is stopped, the supply of the clock signal is resumed. If the supply of power to the transmission amplifier has been stopped, the supply of power is resumed.

  Two specific examples of a method for detecting that the connection with the backhaul has been recovered are disclosed below. (1) When the connection disconnection detection unit 605b receives a response signal from the HeNB-GW 602 or the EPC 601, the connection disconnection detection unit 605b determines that the connection with the backhaul has been recovered. (2) When the connection disconnection detection unit 605b receives data (user data, control data) from the HeNB-GW 602 or the EPC 601, the connection disconnection detection unit 605b determines that the connection with the backhaul has been recovered.

  Five specific examples of the control signal notified from the connection disconnection detection unit 605b to the HeNB 606 are disclosed below. (1) Information on whether or not the connection with the backhaul has been restored. (2) Information indicating that the connection with the backhaul has been restored. (3) Information indicating that the connection with the backhaul has not been recovered. (4) Instruction information for transition to normal operation. (5) Non-permission information for transition to the energy saving operation.

  As described above, according to the present embodiment, when the connection with the backhaul of HeNB 606 is disconnected and the base station cannot operate, the HeNB 606 is allowed to perform the energy saving operation. As a result, the power consumption can be reduced as compared with the case where the HeNB 606, which cannot operate as a base station, performs the normal operation. Therefore, it is possible to efficiently reduce power consumption in the HeNB 606 that is a network node in the local area range.

Embodiment 2. FIG.
A problem to be solved in the second embodiment will be described. When the line quality of the HeNB backhaul deteriorates, the throughput also deteriorates on the UE side. If the throughput is improved by connecting to a neighboring eNB, there may be no merit of connecting to the HeNB. Thus, when the line quality of the backhaul of HeNB deteriorates, if the normal operation of HeNB is continued, there exists a subject that the throughput by UE side will deteriorate.

  A solution in the second embodiment will be described below. FIG. 14 is a block diagram showing a configuration of HeNB 1200 according to the second embodiment of the present invention. The HeNB 1200 has a function of measuring the line quality of the backhaul. The HeNB 1200 includes an EPC communication unit 1201, another base station communication unit 1202, a protocol communication unit 1203, a transmission data buffer unit 1204, an encoder unit 1205, a modulation unit 1206, a frequency conversion unit 1207, an antenna 1208, a demodulation unit 1209, a decoder unit 1210, A control unit 1211 and a line quality measurement unit 1212 are provided. The control unit 1211 and the line quality measurement unit 1212 correspond to a line quality comparison unit. In the current 3GPP, the X2 interface between HeNBs is not supported. However, since it is considered that the X2 interface between the HeNBs is supported depending on the future discussion, the other base station communication unit 1202 (X2 interface) will also be described in the present embodiment and FIG.

  The EPC communication unit 1201 transmits and receives data to and from an EPC that is a core network that integrally accommodates access networks such as LTE, 3G, and wireless LAN. The control unit 1211 performs setting of each block configuring the HeNB 1200 and the like.

  EPC communication unit 1201, other base station communication unit 1202, protocol communication unit 1203, transmission data buffer unit 1204, encoder unit 1205, modulation unit 1206, frequency conversion unit 1207, antenna 1208, demodulation unit 1209, decoder unit 1210 and control unit 1211 Are respectively the EPC communication unit 901, the other base station communication unit 902, the protocol communication unit 903, the transmission data buffer unit 904, the encoder unit 905, the modulation unit 906, the frequency conversion unit 907, of the base station 72 shown in FIG. The antenna 908, the demodulation unit 909, the decoder unit 910, and the control unit 911 have the same configuration. In the present embodiment, EPC communication unit 1201 and protocol processing unit 1203 are connected via line quality measurement unit 1212. Further, the other base station communication unit 1202 and the protocol processing unit 1203 are connected via a line quality measurement unit 1212.

  The HeNB 1200 compares the channel quality of the own HeNB 1200 with the channel quality of other base stations. When it is determined that the channel quality of another base station is better, the HeNB 1200 operates such that a UE being served by the own cell is connected to another base station.

  Three specific examples of channel quality are disclosed below. (1) Throughput. The amount of communication data per fixed time. (2) Bit error rate (BER). (3) Frame discard rate.

  Two specific examples of a method for comparing the channel quality of the own HeNB 1200 and the channel quality of another base station are disclosed below. (1) Compare the wireless channel quality in the wireless section. (2) Compare backhaul line quality.

  A specific example of the method for comparing the radio channel qualities of the radio sections in the specific example (1) will be disclosed below.

  First, a specific example of a method for measuring radio channel quality between the own HeNB 1200 and a UE being served thereby will be disclosed below. In HeNB 1200, a radio signal from a UE being served thereby is received by antenna 1208, and is provided to frequency conversion section 1207 as a received signal. The received signal is converted into a baseband signal by the frequency conversion unit 1207, and detection processing and demodulation processing are performed by the demodulation unit 1209. The demodulated data is given to the decoder unit 1210 and decoded by performing a decoding process such as error correction. Of the decoded data, control data and call control information are provided to the EPC communication unit 1201 and the protocol processing unit 1203. As a result, quality measurement information is given from the EPC communication unit 1201 and the protocol processing unit 1203 to the line quality measurement unit 1212.

  The channel quality measurement unit 1212 is based on the quality measurement information given from the EPC communication unit 1201 and the protocol processing unit 1203, and is the radio channel quality that is the transmission quality of the radio channel between the HeNB 1200 and the UE, that is, between the HeNB 1200 and the UE. Measure the quality of the radio link established between them. The radio channel quality may be directly measured by the channel quality measuring unit 1212. The demodulating unit 1209 and the decoder unit 1210 measure the channel quality, and the information is transmitted to the channel quality via the protocol processing unit 1203 and the EPC communication unit 1201. By giving to the measurement unit 1212, the line quality measurement unit 1212 may obtain the line quality. Examples of the radio channel quality in the radio section include a reception level and a signal to interference ratio (SIR).

  Next, a specific example of a method for acquiring radio channel quality (hereinafter sometimes referred to as “radio channel quality of another base station”) between another base station and a UE being served by another base station is disclosed below. To do. In the HeNB 1200, information on the radio channel quality of other base stations is received by the channel quality measurement unit 1212 via the other base station communication unit 1202 or the EPC communication unit 1201. The information on the radio channel quality of other base stations is the radio channel quality that is the transmission quality of radio channels between other base stations and UEs being served by other base stations, that is, between other base stations and UEs. Represents the quality of the other wireless link that is the wireless link established by Reception of radio channel quality information of other base stations in the HeNB 1200 of this specific example is achieved by a base station realized by the HeNB 1200 in which a certain UE includes an antenna 1208, a frequency conversion unit 1207, a demodulation unit 1209, and a decoder unit 1210. It is effective when connected to both the base station and another base station that performs communication via the other base station communication unit 1202. This is because channel quality in actual UEs can be compared.

  The channel quality measurement unit 1212 establishes a radio channel with higher quality, that is, a radio channel with higher quality among the radio channel between the HeNB 1200 and the UE as the own device and the radio channel with another base station and the UE. It is determined that communication should be performed with a base station that is currently operating, specifically, a base station with high channel quality. Examples of wireless channel quality in the wireless section include reception level and SIR.

  The control unit 1211 controls the operation of the HeNB 1200 based on the determination of the channel quality measurement unit 1212. Specifically, when the channel quality measurement unit 1212 determines that the quality of the radio channel between the other base station and the UE is higher and determines that communication with the other base station should be performed, the control is performed. The unit 1211 stops the input of the clock signal to the modulation unit 1206 or the demodulation unit 1209 on the HeNB 1200 side as its own device, or stops the power supply to the transmission amplifier connected to the antenna 1208 Perform the action. At this time, the transmission data buffer unit 1204 and the decoder unit 1210 which are backhaul side interface (I / F) units are operated as they are. That is, in the present embodiment, as the energy saving operation of the HeNB 1200, transmission / reception is turned off (OFF) and the backhaul side I / F unit is turned on.

  Of the specific examples of the method of comparing the channel quality of the own HeNB 1200 and the channel quality of another base station, a specific example of the method of comparing the channel quality of the backhaul of the specific example (2) will be disclosed below.

  A specific example of the method for measuring the channel quality of the backhaul of the own HeNB 1200 will be disclosed below. The EPC communication unit 1201 or the line quality measuring unit 1212 measures the line quality of the backhaul.

  A specific example of a method for acquiring the channel quality of the backhaul of another base station will be disclosed below. The EPC communication unit 1201 or the channel quality measurement unit 1212 of another base station measures the channel quality of the backhaul. The channel quality measurement unit 1212 of the own HeNB 1200 receives the measurement result via the other base station communication unit 1202 or the EPC communication unit 1201.

  The channel quality measurement unit 1212 has established a radio channel having higher quality, that is, a higher quality radio channel, among the backhaul channel of the HeNB 1200 as its own device and the backhaul channel of another base station. It is determined that communication should be performed with a base station, specifically, a base station with high channel quality.

  As a specific example of the method of comparing the line quality of the backhaul, a case where the line quality on the wired side is measured is shown below.

  When measuring the line quality on the wired side, the line quality measurement unit 1212 receives the Ethernet frame discard rate (from the protocol check unit 1203 and the EPC communication unit 1201 based on the frame check result of the Ethernet (registered trademark) frame ( Hereinafter, it may be referred to as “frame discard rate”), and the time during which the rate control setting between the HeNB 1200 as its own device and the network in another base station remains at a low rate (hereinafter referred to as “low rate duration”). Is obtained as the line quality on the wired side. Then, the line quality measurement unit 1212 makes a determination based on the frame discard rate and the low rate duration.

  For example, when the frame discard rate in the HeNB 1200 that is the device itself is higher, the channel quality measurement unit 1212 determines that communication should be performed with a base station with a lower frame discard rate, that is, another base station. . In addition, when the low rate duration in the own apparatus is shorter, the channel quality measurement unit 1212 determines that communication should be performed with the base station with the longer low rate duration, that is, another base station.

  Two specific examples of the operation of causing the UE being served by the own cell to connect to another base station are disclosed below. (1) The own HeNB is shifted to the energy saving operation. (2) The own HeNB is prevented from being selected by the UE from being selected as a handover destination.

  A specific example of a method of shifting the own HeNB of the specific example (1) to the energy saving operation will be disclosed below. When the channel quality measurement unit 1212 determines that communication with another base station is to be performed, the control unit 1211 transmits the modulation to the modulation unit 1206 or the demodulation unit 1209 so that the other base station communicates with the UE. The energy saving operation such as stopping the input of the clock signal or stopping the supply of power to the transmission amplifier connected to the antenna 1208 is performed. At this time, the transmission data buffer unit 1204 and the decoder unit 1210 as the I / F unit on the backhaul side are operated as they are. That is, as the energy saving operation of the HeNB, transmission / reception is turned off (OFF) and the backhaul I / F unit is turned on. Thereby, reception quality (RSRP etc.) of HeNB1200 in UEs being served thereby decreases, and cell reselection or handover is executed.

  A specific example of a method for preventing the own HeNB of the specific example (2) from being selected by the UE or not being selected as a handover destination from the UE will be disclosed below. The HeNB 1200 transmits information instructing not to include the own cell as a selection target as a cell selection destination or a handover destination. Broadcast information may be used for the transmission. The mobile terminal in the coverage can be notified regardless of the state of the mobile terminal (UE) (standby or busy). As a result, it is possible to prevent further UE connections and the like while maintaining the connection of the UEs being served thereby.

  The channel quality measurement unit 1212 is provided on the HeNB 1200 side in the present embodiment, but may be provided on the core network side. When the line quality measurement unit 1212 is on the HeNB 1200 side as in the present embodiment, when the line quality measurement result determines that the line quality on the HeNB 1200 side is deteriorated, an alarm signal is output to the core network side and the backhaul is performed. Notify that the energy saving operation is performed due to quality deterioration. When notifying that the energy saving operation is performed, the HeNB 1200 stops the input of the clock signal to the modulation unit 1206 or the demodulation unit 1209 or the power to the transmission amplifier connected to the antenna 1208 as described above. An energy saving operation such as stopping the supply is performed. At this time, the transmission data buffer unit 1204 and the decoder unit 1210 as the I / F unit on the backhaul side are operated as they are. That is, as the energy saving operation of the HeNB 1200, transmission / reception is turned off (OFF) and the backhaul I / F unit is turned on.

  As described above, according to the present embodiment, when a user receives a disadvantage due to a decrease in backhaul quality and a decrease in throughput, for example, when a dedicated service of the HeNB 1200 cannot be received, an energy saving operation is performed in the HeNB 1200. To do. As a result, the UE used by the user can be prompted to communicate with another base station, so that the possibility of the user receiving a disadvantage can be reduced.

  In the present embodiment, the HeNB 1200 is operated in a normal operation state when a higher-quality radio channel can be established with the UE than other base stations, and the radio with lower quality is used. When the line is established, the low power operation state is entered. Thereby, compared with the case where HeNB1200 is always operated in a normal operation state, power consumption can be reduced. Therefore, low power consumption can be efficiently performed in the HeNB 1200 that is a network node in the local area range.

  Further, in the present embodiment, when the HeNB 1200 detects the deterioration of the backhaul line quality toward the core network by the line quality measurement unit 1212, the HeNB 1200 notifies the core network side of the decrease in the backhaul line quality toward the core network. To do. As a result, the operator on the core network side can recognize that the HeNB 1200 is performing an energy saving operation due to an abnormality in the backhaul line. Further, the operator on the core network side notifies the UE being served by the HeNB 1200 that the energy saving operation due to the backhaul line abnormality is being performed, so that the user of the UE can also receive the energy saving due to the backhaul line abnormality. It can be recognized that it is an operation.

Embodiment 3 FIG.
A problem to be solved in the third embodiment will be described. In the normal operation described above, the HeNB operates only for registered UEs, but the number of HeNBs accommodated is larger than the number of registered UEs (hereinafter referred to as “number of registered users”) (HeNB accommodation). Number> number of registered users), a circuit that does not operate is generated. Since power is also supplied to a circuit that does not operate in this way, there arises a problem that power consumption is wasted.

  A solution in the third embodiment for solving the above problem will be described below. FIG.15 and FIG.16 is a block diagram which shows the structure of HeNB of Embodiment 3 of this invention. FIG. 15 shows a configuration when the number of registered users is “4”, and FIG. 16 shows a configuration when the number of registered users is “1”. The HeNB when the number of registered users shown in FIG. 15 is “4” is indicated by reference numeral 700, and the HeNB when the number of registered users shown in FIG. 16 is “1” is indicated by reference numeral 700A. Similarly to the HeNB 606 shown in FIG. 13 described above, the HeNBs 700 and 700A are connected to an EPC 601 that is a core network including an MME and the like via a backhaul such as a HeNB-GW 602.

  The HeNBs 700 and 700A of the present embodiment are configured to store UEs registered as users (hereinafter may be referred to as “registered UEs”). HeNB700, 700A acquires the information of UE registered into this HeNB700, 700A with the following methods. For example, when the UE registers the HeNB 700 or 700A, specifically, when registering the CSG-ID of the HeNB 700 or 700A, the MME notifies the HeNB 700 or 700A of the UE information to be registered. Or you may notify by the owner of HeNB. Moreover, you may notify from UE registered. Thereby, HeNB700, 700A acquires the information of registration UE. The MME sets the attributes of the UE in which the CSG-ID of the HeNB 700, 700A is registered in the HeNB 700, 700A, for example, the UE identifier (UE-ID; Subscriber Identifier (International Mobile Subscriber Identity: IMSI), etc.), the UE category. It is comprised so that it may notify and memorize | store in HeNB700,700A.

  The HeNBs 700 and 700A of the present embodiment constitute a service for acquiring UEs registered in the HeNBs 700 and 700A from the network (Network: NW) side.

  The HeNB 700 illustrated in FIG. 15 includes a rewritable device 701, a CPU (Central Processing Unit) 702, a user number registration memory 703, and a ROM (Read Only Member) 704. A rewritable device 701 shown in FIG. 15 is a rewritable logic circuit device when the number of registered users is 4, and includes four user processing circuits 705. The user processing circuit 705 processes a wireless communication operation with the UE. The CPU 702 comprehensively controls the rewritable device 701, the user number registration memory 703, and the ROM 704. The user number registration memory 703 stores the number of registered users. The ROM 704 stores logic circuit binary data having circuit information up to the maximum capacity.

  A HeNB 700A illustrated in FIG. 16 includes a rewritable device 701A, a CPU 702, a user number registration memory 703, and a ROM 704. In HeNB700A shown in FIG. 16, the structure other than rewritable device 701A is the same as that of HeNB700 shown in FIG. A rewritable device 701A illustrated in FIG. 16 is a rewritable logic circuit device when the number of registered users is 1, and includes one user processing circuit 705. In the HeNB 700A illustrated in FIG. 16, the CPU 702 comprehensively controls the rewritable device 701A, the user number registration memory 703, and the ROM 704.

  The rewritable devices 701 and 701A of the HeNBs 700 and 700A correspond to processing means. The rewritable devices 701 and 701A are realized by an FPGA (Field Programmable Gate Array) or the like. The HeNBs 700 and 700A statically change the circuit configuration of the rewritable devices 701 and 701A according to the number of registered users (hereinafter may be referred to as “the number of UEs”), and the accommodated number of HeNBs 700 and 700A is equal to or less than the number of registered users. (HeNB accommodation number ≦ registered user number).

  The HeNBs 700 and 700A of the present embodiment operate as follows. The ROM 704 stores logic circuit binary data having circuit information of 1, 2,... When the HeNBs 700 and 700A are activated, the CPU 702 starts an activation operation. Specifically, the CPU 702 reads the number of registered users from the user number registration memory 703, reads the logic circuit binary data corresponding to the corresponding number of registered users from the ROM 704, and develops the rewritable devices 701 and 701 </ b> A. The CPU 702 corresponds to a rewriting unit.

  At the stage where the start-up operation is completed, the rewritable devices 701 and 701A are in a state in which only the user processing circuits 705 corresponding to the number of registered users exist and there are no circuits that do not operate. For example, when the number of registered users is “4”, as shown in FIG. 15, only four user processing circuits 705 exist, and no non-operational circuit exists. When the number of registered users is “1”, as shown in FIG. 16, there is only one user processing circuit 705 and no non-operating circuit. The HeNBs 700 and 700A perform the above-described normal operation in a state where there are only circuits for the number of registered users.

  As described above, according to the present embodiment, the HeNBs 700 and 700A include the rewritable devices 701 and 701A, and the CPU 702 develops the logic circuit binary data corresponding to the number of registered users in the rewritable devices 701 and 701A. Specifically, the CPU 702 rewrites the user processing circuits 705 of the rewritable devices 701 and 701A so that the same number of user processing circuits 705 as the number of registered users are formed. As a result, when the number of registered users is small with respect to the number of UEs that can be accommodated in the HeNBs 700 and 700A, it is possible to limit the circuit to operate, so that the circuit configuration according to the number of registered users can be obtained. Accordingly, the power consumption of the HeNBs 700 and 700A during normal operation can be reduced as compared with the case where the same number of user processing circuits 705 as the number of UEs that can be accommodated is provided in advance. It is possible to efficiently reduce power consumption in the station apparatus.

  In the present embodiment, HeNBs 700 and 700A are configured to be able to switch between a normal operation and an energy saving operation. For example, the HeNBs 700 and 700A shift from the normal operation to the energy saving operation in the following cases (1) to (3).

  (1) A UE connected to the HeNBs 700 and 700A does not exist for a predetermined period. Specifically, when there is no CONNECTED UE for a certain period under the HeNB 700, 700A, or when there is only an IDLE UE for a certain period under the HeNB 700, 700A.

  (2) When the power consumption reduction switch of the HeNB 700 or 700A is turned on.

  (3) When a transition from the MME or the like to the energy saving operation is instructed.

  The HeNBs 700 and 700A stop the transmission operation of the downlink transmission signal to the UE, for example, as the energy saving operation, and continue the reception operation of the uplink transmission signal from the UE. That is, the transmission operation is turned off and the reception operation is turned on.

  As a specific method for setting the transmission operation to the OFF state, the same method as the method for setting the transmission / reception operation to the OFF state in the first and second embodiments described above may be used. Specifically, the input of the clock signal to the modulation unit is stopped, or the supply of power to the transmission amplifier connected to the antenna is stopped.

  In the on state of the reception operation, the HeNBs 700 and 700A are in a state in which the uplink transmission signal transmitted from the UE can be received. At this time, the HeNBs 700 and 700A may perform a continuous reception operation in which the uplink transmission signal transmitted from the UE can be always received, but may perform an intermittent reception operation in which the uplink reception signal is intermittently received. Good. The intermittent reception operation is effective in reducing power consumption compared to the continuous reception operation.

  For example, when receiving an uplink transmission signal for wakeup transmitted from the UE in the energy saving operation state, the HeNBs 700 and 700A shift from the energy saving operation to the normal operation. Here, the uplink transmission signal for wakeup refers to an uplink transmission signal transmitted from the UE in order to shift the HeNBs 700 and 700A from the energy saving operation to the normal operation.

  The UE stores the UE identification number (UE-ID) in the wake-up uplink transmission signal and transmits it. In the present embodiment, the MME is configured to have a function of notifying the HeNB 700 and 700A of the attribute of the registered UE and storing the attribute as described above, so the HeNB 700 and 700A stores the attribute of the registered UE. ing. Accordingly, when the uplink transmission setting for wakeup is changed from the setting A to the setting B, for example, the HeNBs 700 and 700A start from the UE-ID when the uplink transmission signal for wakeup is received from the UE in the state of the setting B. Thus, it can be recognized that the uplink transmission setting has been updated.

Embodiment 4 FIG.
A problem to be solved in the fourth embodiment will be described. Depending on the number of UEs permitted to connect to the HeNB and the performance of the UE, the frequency bandwidth covered by the HeNB may be over-specification, that is, excessive. When processing is performed with a wide bandwidth, there arises a problem that power consumption is wasted.

  A solution in the fourth embodiment for solving the above problem will be described below. FIG. 17 is a block diagram showing a configuration of HeNB 1300 according to Embodiment 4 of the present invention. The HeNB 1300 of the present embodiment has the same configuration as the HeNB 1200 of the second embodiment shown in FIG. 14, and thus the corresponding parts are denoted by the same reference numerals and common description is omitted.

  The HeNB 1300 according to the present embodiment includes an EPC communication unit 1201, another base station communication unit 1202, a protocol communication unit 1203, a transmission data buffer unit 1204, an encoder unit 1205, a modulation unit 1206, a frequency conversion unit 1207, an antenna 1208, and a demodulation unit 1209. A decoder unit 1210, a control unit 1211, a band switching unit 1301, an RF (Radio Frequency) unit 1302, a registered UE attribute storage unit 1303, and an operating frequency switching unit 1304. The RF unit 1302 corresponds to a radio unit and performs radio communication with the UE. The HeNB 1300 is connected to an EPC 601 that is a core network including an MME and the like through a backhaul such as the HeNB-GW 602, similarly to the HeNB 606 illustrated in FIG.

  The RF unit 1302 includes an RF circuit compatible with a wide band (hereinafter also referred to as “broadband RF circuit”) and an RF circuit compatible with a narrow band (hereinafter also referred to as “narrowband RF circuit”). The wideband RF circuit includes a wideband band limiting filter and an amplifier. The narrowband RF circuit includes a narrowband band limiting filter and an amplifier. In FIG. 17, wideband and narrowband amplifiers are shown as representatives, but the number of amplifiers is not limited to two.

  The band limiting filter limits a band in which the HeNB 1300 performs processing (hereinafter may be referred to as “processing band”) to a predetermined band. The wideband band limiting filter limits the processing band to a relatively wide band. The band limiting filter for narrow band limits the processing band to a relatively narrow band. The band switching unit 1301 switches the frequency band used by the RF unit 1302. Specifically, the band switching unit 1301 selects a band limiting filter of the RF unit 1302. An RF circuit including a band limiting filter selected by the band switching unit 1301 is connected to the frequency conversion unit 1207 and the antenna 1208 to operate. For example, when a band-limiting filter for broadband is selected by the band switching unit 1301, the broadband RF circuit is connected to the frequency converter 1207 and the antenna 1208, and the processing band of the HeNB 1300 is selected to be broadband. When a band limiting filter for narrow band is selected by the band switching unit 1301, the narrow band RF circuit is connected to the frequency converting unit 1207 and the antenna 1208, and the processing band of the HeNB 1300 is selected to be a narrow band.

  The operating frequency switching unit 1304 switches the operating frequency of the HeNB 1300, that is, the clock frequency, according to the processing band of the HeNB 1300. When the processing band of the HeNB 1300 is selected to be a wide band, a relatively high-speed clock (hereinafter may be referred to as “high-speed clock for broadband”) is used, and when the processing band of the HeNB 1300 is selected to be a narrow band, A low-speed clock (hereinafter sometimes referred to as a “low-speed clock for narrow band”) is used. The operating frequency switching unit 1304 switches between a broadband high-speed clock and a narrow-band low-speed clock.

  The registered UE attribute storage unit 1303 stores information on registered UEs. Information on the registered UE corresponds to mobile terminal information. The information on the registered UE includes at least one of the number and attributes of UEs registered in the HeNB 1300. Examples of registered UE attributes include UE-ID and UE category. The UE category defines UE performance. The HeNB 1300 according to the present embodiment acquires UE information to be registered in the HeNB 1300 by the following method and the like, similar to the HeNB 700 and 700A according to the third embodiment shown in FIGS. 15 and 16 described above.

  For example, when the UE registers a HeNB, specifically, when registering the CSG-ID of the HeNB 1300, the MME notifies the HeNB 1300 of information on the UE to be registered. Or you may notify by the owner of HeNB. Moreover, you may notify from UE registered. Thereby, the HeNB 1300 acquires information on the registered UE. The MME registers information of registered UEs in the HeNB 1300, specifically, the number of UEs in which the CSG-ID of the HeNB 1300 is registered, and UE attributes, for example, UE identifier (UE-ID; IMSI, etc.), UE category It is comprised so that it may notify and memorize | store in HeNB1300.

  Moreover, you may memorize | store the information of the intention of the owner of HeNB. A specific example of owner's intention information is disclosed below. (1) Information on whether or not priority is given to low power consumption. (2) Information indicating low power consumption priority. (3) Information indicating that low power consumption is not prioritized. (4) Information about whether or not priority is given to throughput. (5) Information indicating that priority is given to throughput. (6) Information indicating that throughput is not prioritized. Two specific examples of the owner's intention input method are disclosed below. (1) HeNB external button. (2) Communication from the registered UE. For the communication, infrared communication or the like can be used.

  Further, the HeNB 1300 according to the present embodiment is configured to be able to switch between a normal operation and an energy saving operation, similarly to the HeNBs 700 and 700A shown in FIGS. 15 and 16 described above. The UE stores the UE identification number (UE-ID) in the wake-up uplink transmission signal and transmits it. In this Embodiment, since MME is comprised so that it may have the function to notify and memorize | store the attribute of registration UE in HeNB1300 as mentioned above, HeNB1300 has memorize | stored the attribute of registration UE.

  Thereby, for example, when the uplink transmission setting for wakeup is changed from the setting A to the setting B, the HeNB 1300 receives the uplink from the UE-ID when the wakeup uplink transmission signal is received from the UE in the state of the setting B. It can be recognized that the transmission setting has been updated.

  The HeNB 1300 according to the present embodiment operates as follows. The control unit 1211 acquires information on the registered UE from the registered UE attribute storage unit 1303. The control unit 1211 obtains a frequency band that the HeNB 1300 needs as a processing band based on the acquired information of the registered UE. Then, the control unit 1211 performs processing band selection by selecting a band limiting filter and an amplifier of the RF unit 1302 by the band switching unit 1301 according to the obtained frequency band.

  The control unit 1211 switches the operating frequency by the operating frequency switching unit 1304 according to the frequency band obtained as the processing band. When the processing band is a narrow band, the control unit 1211 reduces the operating frequency, that is, switches to a low-speed clock. When the processing band is narrow, the transmission rate is low, but the degree of the low-speed clock is selected so that the processing time is sufficient for the system even at the low transmission rate. By reducing the clock frequency, power consumption can be reduced.

  Eight specific examples of selecting a frequency band are disclosed below.

  (1) When the number of registered UEs is small, it is determined that the radio resources to be used may be small, and the band switching unit 1301 selects a band-limiting filter and amplifier for narrow band. The operating frequency switching unit 1304 selects a low-speed clock for narrow band. On the other hand, when the number of registered UEs is large, it is determined that a large amount of radio resources are necessary, and the band switching unit 1301 selects a band limiting filter and an amplifier for wide band. Further, the operating frequency switching unit 1304 selects a broadband high-speed clock.

  (2) When the category of the registered UE indicates low performance (Capability), it is determined that the radio resource to be used is small, and the band switching unit 1301 selects a band limiting filter and an amplifier for narrow band. . The operating frequency switching unit 1304 selects a low-speed clock for narrow band. On the other hand, when the category of the registered UE indicates high performance, it is determined that a large amount of radio resources are necessary, and the band switching unit 1301 selects a band limiting filter and an amplifier for broadband. Further, the operating frequency switching unit 1304 selects a broadband high-speed clock.

  (3) When the information on the intention of the owner of the HeNB indicates low power consumption priority, the band switching unit 1301 selects a band-limiting filter and amplifier for narrow band effective for low power consumption. The operating frequency switching unit 1304 selects a low-speed clock for narrow band. On the other hand, when the information on the intention of the owner indicates that low power consumption is not prioritized, the band switching unit 1301 selects a band limiting filter and an amplifier for a wide band. Further, the operating frequency switching unit 1304 selects a broadband high-speed clock. Note that the owner can manually indicate low power consumption priority to the HeNB, or can automatically indicate low power consumption priority by time designation. In the case of manual operation, switching can be performed by transmitting a control signal from the external switch to the band switching unit 1301.

  (4) When the information on the intention of the owner of the HeNB does not indicate throughput priority, the band switching unit 1301 selects a band limiting filter and an amplifier for narrow band. The operating frequency switching unit 1304 selects a low-speed clock for narrow band. On the other hand, when the owner's intention information indicates throughput priority, the band switching unit 1301 selects a band-limiting filter and amplifier for broadband. Further, the operating frequency switching unit 1304 selects a broadband high-speed clock.

  (5) When there is no data exchange with the host device, the band switching unit 1301 selects a band-limiting filter and amplifier for narrow band effective for low power consumption. The operating frequency switching unit 1304 selects a low-speed clock for narrow band. On the other hand, when the information on the intention of the owner indicates that low power consumption is not prioritized, the band switching unit 1301 selects a band limiting filter and an amplifier for a wide band. Further, the operating frequency switching unit 1304 selects a broadband high-speed clock.

  (6) When a low power consumption operation is instructed by a host device due to a request from an electric power company or the like, the band switching unit 1301 selects a band limiting filter and amplifier for narrow band effective for low power consumption. The operating frequency switching unit 1304 selects a low-speed clock for narrow band. On the other hand, when the information on the intention of the owner indicates that low power consumption is not prioritized, the band switching unit 1301 selects a band limiting filter and an amplifier for a wide band. Further, the operating frequency switching unit 1304 selects a broadband high-speed clock.

  (7) When communication has not been performed between the HeNB and the terminal (UE) for a certain period of time, the band switching unit 1301 selects a band-limiting filter and amplifier for narrow band that are effective for low power consumption. The operating frequency switching unit 1304 selects a low-speed clock for narrow band. On the other hand, when the information on the intention of the owner indicates that low power consumption is not prioritized, the band switching unit 1301 selects a band limiting filter and an amplifier for a wide band. Further, the operating frequency switching unit 1304 selects a broadband high-speed clock.

  (8) When it is a time zone with little traffic such as dawn or midnight, the band switching unit 1301 selects a band-limiting filter and amplifier for narrow band effective for low power consumption. The operating frequency switching unit 1304 selects a low-speed clock for narrow band. On the other hand, when the intention of the owner indicates that priority is not given to low power consumption, the band switching unit 1301 selects a band-limiting filter and amplifier for broadband. Further, the operating frequency switching unit 1304 selects a broadband high-speed clock.

  Information on the registered UE including the number of registered UEs in the specific example (1) and the category of the registered UE in the specific example (2), information on the intention of the owner of the HeNB in the specific examples (3) and (4) Information on whether or not there is data exchange with the higher-level device in the specific example (5), information on whether or not communication is performed between the HeNB and the UE in the specific example (7) for a certain period of time, The information on whether or not the time zone in which the traffic is low in the example (8) corresponds to information determined by the base station device. The higher-level devices in specific examples (5) and (6) correspond to base-station higher-level devices, and specifically are MME, HeNB-GW, and the like. The low power consumption operation instruction from the host device in the specific example (6) corresponds to the instruction from the base station host device.

  In HeNB 1300, modulation section 1206, demodulation section 1209, encoder section 1205, and decoder section 1210 constitute a baseband signal processing section. Each unit constituting the baseband signal processing unit, that is, the modulation unit 1206, the demodulation unit 1209, the encoder unit 1205, and the decoder unit 1210 is set as a synchronous circuit that supplies the same clock. As a result, the clock signal can be supplied from the clock transmitter in a unified manner, so that the respective parts constituting the baseband signal processing unit can operate in synchronism even when the clock frequency is changed.

  The system timing counter inside the device is a circuit using an enable signal or the like so that the counter change period should not change for those specified in 3GPP etc. so that it will not change even if the clock frequency changes. deep. Changes in the timing relationship with the host device are absorbed by the transmission data buffer unit 1204 on the transmission side.

  As described above, in the present embodiment, the registered UE attribute storage unit 1303 stores the number of UEs registered in the HeNB 1300 and the UE category. From these pieces of information, the control unit 1211 obtains a frequency band that the HeNB 1300 needs as a processing band, selects a band limiting filter of the RF unit 1302 by the band switching unit 1213 according to the obtained frequency band, An RF circuit or a narrowband RF circuit is selected. If the UE supports a narrow band and does not require a wide band, a narrow band RF circuit is selected. Thereby, power consumption can be reduced.

  Thus, by limiting the operation of the HeNB 1300 in accordance with the number and attributes of UEs registered in the HeNB 1300, the power consumption of the HeNB 1300 can be reduced. Therefore, low power consumption can be efficiently performed in the HeNB 1300 that is a network node in the local area range.

  Also, instead of the number and attributes of UEs to be registered, based on information determined by the base station device such as information on whether or not there is data exchange with the above-described host device, or based on an instruction from the base station host device The same effect can be obtained when the frequency band required as the processing band is switched. Based on the information determined by the base station apparatus, the frequency band used as a processing band is switched to limit the frequency band used in the radio unit according to the information determined by the base station apparatus. The operation of the unit can be restricted and the power consumption can be reduced. In addition, by switching the frequency band required as a processing band based on an instruction from the base station host apparatus, the radio unit limits the frequency band used in the radio unit according to the instruction from the base station host apparatus. The operation can be limited and the power consumption can be reduced. Therefore, in any case, it is possible to efficiently reduce the power consumption in the base station apparatus which is a network node in the local area range.

  In the present embodiment, a high-speed clock for a wide band, a band-limiting filter and an amplifier for a wide band, a low-speed clock for a narrow band, a band-limiting filter and an amplifier for a narrow band, The amplifiers may be independent from each other. That is, it is possible to select a wideband band limiting filter and amplifier or a narrowband band limiting filter and amplifier by the control signal without changing the clock speed.

  Further, as a concept of bandwidth limitation, as shown in the prior document “Energy saving at eNB (R1-100298)” (3GPP TSG RAN WG1 Meeting # 59bis Valencia, Spain, January 18-22, 2010, NTT DOCOMO), FIG. When there are two bands A and B, there are a band limiting method for eliminating one band B, or a method for reducing the bandwidths of the same bands A and B, respectively.

  FIG. 18 is a diagram illustrating frequency scheduling. In FIG. 18, squares (□) indicated by diagonal lines represent a cluster of frequencies such as resource blocks. As an example, FIGS. 19 and 20 show subcarriers in which the hatched squares shown in FIG. 18 are drawn as one subcarrier. FIG. 19 is a diagram illustrating an example of one subcarrier, and FIG. 20 is a diagram illustrating subcarriers constituting a frequency band. In FIG. 19, a hatched portion is a portion that may cause interference when the orthogonality is lost due to the state of the wireless transmission path. As shown in FIG. 19, there is a possibility that the orthogonality may be lost between adjacent subcarriers due to transmission path conditions, causing interference.

  FIG. 21 is a diagram showing frequency scheduling and subcarriers when a band limiting method for eliminating one of the two bands A and B shown in FIG. 18 is used. FIG. 22 is a diagram showing frequency scheduling and subcarriers when the method of reducing the bandwidths of the two bands A and B shown in FIG. 18 is used. FIGS. 21A and 22A show frequency scheduling, and FIGS. 21B and 22B show subcarriers. In FIG. 21 (a) and FIG. 22 (a), a cluster of frequencies that does not actually exist is indicated by a broken-line square (□). In FIG. 21 (b) and FIG. 22 (b), subcarriers that do not actually exist are indicated by broken lines. In FIG. 21B and FIG. 22B, a hatched portion is a portion that may cause interference when the orthogonality is lost due to the state of the wireless transmission path.

  The method used in FIG. 21 and FIG. 22 is a band limiting method that keeps adjacent bands together. When the subcarrier orthogonality between adjacent frequencies collapses due to problems such as distortion of the wireless transmission path. The problem of causing intersubcarrier interference remains as it is. For example, as shown in FIGS. 21 (b) and 22 (b), there is a possibility that the orthogonality may be lost between adjacent subcarriers due to transmission path conditions, causing interference.

  Therefore, it is conceivable to eliminate data transmission alternately for each sub-carrier in a minimum unit for each frequency block such as a resource block. FIG. 23 is a diagram showing frequency scheduling and subcarriers in the case of using a band limiting method that eliminates data transmission alternately for each subcarrier. FIG. 23A shows frequency scheduling, and FIG. 23B shows subcarriers. In FIG. 23A, a cluster of frequencies that do not actually exist is indicated by a broken-line square (□). In FIG. 23B, subcarriers that do not actually exist are indicated by broken lines. In FIG. 23B, a hatched portion is a portion that may cause interference when the orthogonality is lost due to the state of the wireless transmission path.

  As shown in FIG. 23 (b), interference between subcarriers can be reduced by performing decimation so that adjacent subcarriers are not transmitted. As a result, the transmission power can be kept small, leading to power saving. Thus, by limiting the band so as to eliminate data transmission alternately for each sub-carrier of frequencies such as resource blocks, subcarrier interference can be reduced and transmission power can be reduced. As a result, an effect of reducing power consumption can be obtained.

  In each of the above embodiments, the LTE system (E-UTRAN) has been mainly described. However, the mobile communication system of the present invention can be applied to LTE-Advanced (LTE-Advanced) and W-CDMA systems (UTRAN, UMTS). Applicable. In each of the above embodiments, the HeNB is mainly described, but the present invention can be similarly applied to micro cells, pico cells, and relay nodes.

  Although the present invention has been described in detail, the above description is illustrative in all aspects, and the present invention is not limited thereto. It is understood that countless variations that are not illustrated can be envisaged without departing from the scope of the present invention.

  600 mobile communication system, 601 EPC, 602 HeNB-GW, 603 BB access network (IP network), 604 femto base station device, 605 optical line termination device, 605a optical line termination unit, 605b connection disconnection detection unit, 606,700 , 700A, 1200, 1300 HeNB, 701, 701A rewritable device, 702 CPU, 703 user number registration memory, 704 ROM, 705 user processing circuit, 1212 channel quality measurement unit, 1301 band switching unit, 1302 RF unit, 1303 registered UE Attribute storage unit, 1304 operating frequency switching unit.

Claims (1)

A mobile terminal device, a base station device capable of wireless communication with the mobile terminal device, another base station device capable of wireless communication with the mobile terminal device, and the base station device and the other base station device can perform wired communication. A mobile communication system comprising a core network connected to
The quality of the radio channel established between the base station device and the mobile terminal device is compared with the quality of the other radio channel established between the other base station device and the mobile terminal device. With line quality comparison means,
The base station device performs the transmission operation and the reception operation from a normal operation state in which a transmission operation of a downlink transmission signal to be transmitted to the mobile terminal device and a reception operation of an uplink transmission signal transmitted from the mobile terminal device are performed. It is configured to be able to enter a low power operating state that stops,
When the channel quality comparison unit determines that the quality of the other radio channel is higher than the quality of the radio channel and the other radio channel, the channel quality comparing unit shifts to the base station apparatus to the low power operation state. A mobile communication system characterized by instructing to do so.

Images