JP2009159355A - Wireless communication system, base station, and method of controlling base station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption in a base station used in a wireless communication system and to suppress interference into other wireless communication systems. <P>SOLUTION: A wireless communication system 1 includes femto base stations 21A and 21B. The femto base station 21A forms a femto cell 20A while the femto base station 21B forms a femto cell 20B. The femto base station 21B starts to output wireless signals from the self-station based on an output control signal S1 generated according to whether mobile stations within the adjacent femto cell 20A are in the coverage area. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radio communication system including a base station, and more particularly to control of radio signal output of a base station.

  As a base station used in a wireless communication system, an extremely small base station having a cover area (cell radius) of about several tens of meters has been proposed. A cell formed by such a small base station is called a “femto cell”. The cell radius of femtocells is generally compared to cells called “macrocells” with a cell radius of several kilometers to about 10 km and cells called “microcells” with a cell radius of about several hundreds to 1 km. And very small. The femto base station is assumed to be used by connecting to a fixed communication line such as an ADSL (Asymmetric Digital Subscriber Line), an optical fiber, or a coaxial cable.

  Hereinafter, a small base station forming a femto cell is referred to as a “femto base station”. In addition, femto base stations are often arranged in a hierarchy in a large-scale cell such as a macro cell or a micro cell. Hereinafter, large-scale cells in an upper hierarchy such as a macro cell or a micro cell are collectively referred to as “upper layer cells”.

By the way, Patent Document 1 discloses a technique for changing the cell size by increasing or decreasing the transmission power of the pilot signal of the base station according to the traffic volume. Specifically, when the traffic volume of a certain cell increases, the cell size is reduced by reducing the transmission power of the pilot signal of the base station forming the cell with the increased traffic volume, and the cell adjacent thereto A technique for increasing the cell signal size by increasing the transmission power of the pilot signal of the base station forming the base station is disclosed.
JP 2001-160984 A

  As disclosed in Patent Document 1 described above, the conventional base station increases or decreases the transmission power of the radio signal according to the traffic situation of the adjacent cell, but the base station according to the traffic amount of the adjacent cell. The station does not start or stop the radio signal output.

  The inventors of the present application install a femto base station in a commercial facility such as a store or a restaurant, in the vicinity of an outdoor ticket vending machine, etc., and to a mobile station connected to the femto cell or a user possessing this To provide specific services. More specifically, for example, a plurality of femtocells are arranged adjacent to each other in the upper layer cell, and the femtocell at one end of the daisy chain is allowed to be handed over to the mobile station from the upper layer cell (hereinafter, Called an entrance cell). And from the femtocell adjacent to the entrance cell to the femtocell at the other end, the mobile station handover between the adjacent femtocells is permitted, and the mobile station handover from the upper layer cell is made impossible. As a result, at the location of the femto cell (hereinafter referred to as the destination cell) placed at the end of the daisy chain, the mobile station that has traveled to the destination cell along the path that traverses the femto cell connected to the rosary and the destination on the other route The mobile station that has reached the location of the ground cell belongs to a different cell. For this reason, it is possible to determine the service content according to the travel route followed by the mobile station. This technique is described in detail in Japanese Patent Application No. 2007-260109 (filed on Oct. 3, 2007) previously filed by the applicant of the present application.

  When providing a new service using such a femtocell, if the femto base station continuously outputs a radio signal, power consumption increases. That is, when there is no need to provide a service, it is desirable from the viewpoint of power saving to stop the radio signal output of the femtocell. It is also desirable in that interference with other wireless communication systems existing in the vicinity can be suppressed.

  According to a first aspect of the present invention, a first cell is formed, and a first base station that performs radio communication with a mobile station located in the first cell and a second cell are formed. And a second base station that performs radio communication with a mobile station located in the second cell. Furthermore, the radio signal output of the first base station is started or stopped based on the location status of the mobile station in the second cell. Thereby, for example, when the mobile station is located in the second base station (for example, the entrance cell described above), the radio of the first base station (for example, the femto cell or the destination cell adjacent to the entrance cell). Signal output can be started. Further, when the mobile station is not located in the second base station, the radio signal output of the first base station can be stopped. That is, when there is no need to provide the service of the first base station, the radio signal output of the first base station can be stopped, which can contribute to reduction of power consumption and suppression of interference with other radio communication systems. .

  The above-described radio communication system according to the first aspect of the present invention has a hierarchical cell structure in which a lower layer cell group including at least the first and second cells is arranged in an upper layer cell. Also good. At this time, the second cell may be an entrance cell in which handover of the mobile station from the higher layer cell is permitted. The first cell is configured such that the mobile station cannot be handed over from the upper layer cell, and the handover from at least one cell included in the lower layer cell group is permitted. The cell may be reachable by the mobile station via two cells.

  In the wireless communication system configured with the hierarchical cell structure in this way, the first base station selectively performs wireless communication when the mobile station handed over from the upper layer cell is located in the second cell. Signal output can be initiated to prepare for the handover of the mobile station to the first cell. In other words, even if a certain mobile station exists in the vicinity of the first base station without going through the second cell, it is not necessary to provide service to this mobile station, so the radio signal output is stopped. The maintained state can be maintained. That is, the first base station can efficiently output a radio signal according to a situation in which a handover of the mobile station to the first cell is expected.

  According to the present invention, it is possible to reduce power consumption of a base station used in a wireless communication system and suppress interference with other wireless communication systems.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted as necessary for the sake of clarity.

<Embodiment 1 of the Invention>
FIG. 1 shows a configuration of a wireless communication system 1 according to the present embodiment. The wireless communication system 1 includes femto base stations 21B and 21C that switch start and stop of radio wave output according to whether or not a mobile station is located in an adjacent cell. Here, the stop of radio wave output means that the transmission power of a radio signal is reduced from the power level during normal operation for communication with a mobile station to a power level that can be regarded as being substantially stopped. That is, the transmission power of the femto base stations 21B and 21C when the radio wave output is stopped may not be completely zero.

  The radio communication system 1 according to the present embodiment has a hierarchical cell structure in which a plurality of femtocells 20A to 20C are arranged in the area of the macrocell 10. Below, each element shown in FIG. 1 is demonstrated in order. The macro cell 10 is formed by the macro base station 11. A mobile station (for example, mobile station 31B) existing in the macro cell 10 is connected to the macro base station 11 through a radio interface. The macro base station 11 is connected to a radio access network (RAN) 40 and relays traffic between the mobile station (for example, the mobile station 31B) and the RAN 40.

  On the other hand, femtocells 20A to 20C are formed by femto base stations 21A to 21C, respectively. The femtocells 20 </ b> A to 20 </ b> C have a smaller cell radius than the macrocell 10 and are hierarchized within the macrocell 10. Moreover, as shown in FIG. 1, the femtocells 20A to 20C are arranged adjacent to each other in a daisy chain shape.

  The femto base stations 21A to 21C are used by being connected to a fixed communication line such as an ADSL (Asymmetric Digital Subscriber Line), an optical fiber, or a coaxial cable, for example, and an IP network such as an IP (Internet Protocol) communication network or the Internet. And is connected to the RAN 40 via the figure. The femto base stations 21A to 21C relay traffic between the mobile station (for example, the mobile station 31A) and the RAN 40 via an IP network (not shown).

  A radio network controller (RNC) 41 performs radio resource management between subordinate base stations, ie, the macro base station 11 and the femto base stations 21A to 21C in FIG. 1 and mobile stations connected thereto. Do. In addition, the RNC 41 controls handover associated with movement between mobile stations (for example, the mobile stations 31A and 31B). Specifically, a measurement result report on signal quality is received from mobile stations (for example, mobile stations 31A and 31B), the handover of the mobile station is determined based on the measurement result report, and the base station and mobile station Is used to control the handover of the mobile station. Here, the measurement result reported by the mobile station to the RNC 41 is, for example, a received signal level of a signal received from a base station of an adjacent cell, a received SIR (Signal to Interference power Ratio), or the like.

  The mobile stations 31A and 31B store neighboring cell information broadcast from the base station currently receiving service via the downlink control channel. Then, the mobile stations 31A and 31B refer to neighboring cell information to determine neighboring cells that are signal quality measurement targets at the time of handover. Here, the neighboring cell information is information necessary for measuring the signal quality of the signal transmitted by the base station of the neighboring cell. For example, in the case of a cellular communication system in which the base stations are asynchronous as in the W-CDMA standard cellular communication system, the spreading code used by the base station of the adjacent cell is notified to the mobile stations 31A and 31B by the adjacent cell information. The The mobile stations 31A and 31B can limit the number of spreading codes used for measurement to the number of neighboring cells by sequentially performing despreading processing using spreading codes notified from the base station by neighboring cell information. In addition, a cellular radio communication system in which base stations are synchronized like a cdma2000 standard cellular communication system uses the same spreading code with different delays for each base station apparatus. For this reason, the delay information of the spreading code is also notified as the neighboring cell information together with the spreading code.

  The handover process in the present embodiment is described using a DS-CDMA cellular communication system as an example, but the FH-CDMA (Frequency Hopping Code Division Multiple Access) system, FDMA (Frequency Division Multiple Access) system, etc. Also in other cellular radio communication systems, a mobile station can determine an adjacent cell as a signal quality measurement target by referring to adjacent cell information broadcast from a base station. For example, in the case of FDMA (Frequency Division Multiple Access), the frequency channel used by the base station of the neighboring cell is notified by the neighboring cell information.

  The location register 43 arranged in the core network 42 registers cell information in which each of the mobile stations 31A and B is located in response to a location registration request from the mobile stations 31A and B.

  By the way, in the radio | wireless communications system 1 concerning this Embodiment, the information regarding all the neighboring cells is not necessarily contained in the neighboring cell information alert | reported from the macro base station 11 and the femto base stations 21A-21C. In other words, the contents of the neighboring cell information broadcast from at least some of the macro base station 11 and the femto base stations 21A to 21C are limited to those related to the number of neighboring cells smaller than the total number of neighboring cells. . By restricting the contents of the adjacent cell information in this way, it is possible to control whether the mobile stations 31A and 31B can move between cells.

  FIG. 2 shows a specific setting example of neighboring cell information broadcasted by the macro base station 11 and the femto base stations 21A to 21C. For example, the neighboring cell information broadcast by the macro base station 11 includes the spreading code used by the femto base station 21A, but does not include the spreading code used by the femto base stations 21B and 21C. For this reason, the mobile station belonging to the macro cell 10 can be handed over to the femtocell 20A, but cannot be handed over to the other femtocells 20B and 20C. Although not shown in FIG. 2, it is needless to say that information on other macro cells (not shown) adjacent to the macro cell 10 is included in the adjacent cell information broadcast by the macro base station 11.

  The adjacent cell information broadcast by the femto base station 21A includes a spreading code used by the macro base station 11 and a spreading code used by the femto base station 21B. For this reason, a mobile station belonging to the femtocell 20A can be handed over to the macrocell 10 and the femtocell 20B.

  Also, the neighboring cell information broadcast by the femto base station 21B includes a spreading code used by the macro base station 11, a spreading code used by the femto base station 21A, and a spreading code used by the femto base station 21C. . For this reason, the mobile station belonging to the femtocell 20B can be handed over to the macrocell 10, the femtocell 20A, and the femtocell 20C.

  Further, the neighboring cell information broadcast by the femto base station 21C includes a spreading code used by the macro base station 11 and a spreading code used by the femto base station 21B. For this reason, the mobile station belonging to the femtocell 20C can be handed over to the macrocell 10 and the femtocell 20B.

  By setting the neighboring cell information as shown in FIG. 2, among the femtocells 20 </ b> A to 20 </ b> C, the cell to which the mobile station belonging to the macrocell 10 can move directly by the handover process is limited to the femtocell 20 </ b> A. Is done. That is, the femtocell 20A is an “entrance cell” of the femtocell group including the femtocells 20A to 20C.

  As described above, in the present embodiment, the femtocells 20A to 20C are arranged in a daisy chain in the macrocell 10, and the “entrance cell” that can be handed over from the macrocell 10 is the femtocell 20A. As a result, the mobile stations 31A and 31B located in the space where the femtocell 20C is formed belong to different cells according to the difference in the travel path that has been followed. That is, the mobile station 31A that has moved along the route indicated by the white arrow R1 in FIG. 1 repeats the movement between cells in the order of the macro cell 10, the femto cells 20A, 20B, and 20C. For this reason, the mobile station 31A that has reached the space of the femtocell 20C belongs to the femtocell 20C. On the other hand, the mobile station 31B that has moved along the movement path indicated by the white arrow R2 in FIG. 1 cannot connect to the femtocell 20C due to handover restrictions. For this reason, the mobile station 31B that has reached the area of the femtocell 20C still belongs to the macrocell 10.

  In addition, when the mobile stations 31A and 31B can be connected to a plurality of cells, the mobile stations 31A and 31B may be preferentially connected to a cell having a small cell radius. Thereby, the mobile station 31A can be moved in the order of the femtocell 20B, 20C, and 20D from the femtocell 20A that is an “entrance cell”.

  Further, when the mobile stations 31A and 31B activated from the power-off state perform a cell search to determine a cell to be connected, the macro cell 10 is selected as a connection destination cell instead of the femtocells 20B and 20C. The connection restriction may be performed on the femtocells 20B and 20C.

  As described above, the radio communication system 1 according to the present embodiment can distinguish a mobile station according to a difference in cell to which a mobile station located at the same point belongs. Different services can be provided depending on the cell.

  On the other hand, since the handover of the mobile station is restricted, there is no possibility that the mobile station will move to the femtocells 20B and 20C unless the mobile station is in the femtocell 20A that is the entrance cell. . Therefore, the femto base station 21B according to the present embodiment stops the radio wave output when the mobile station is not located in the adjacent femto cell 20A, and receives the radio wave in response to the handover of the mobile station from the macro cell 10 to the femto cell 20A. Start output. Similarly, the femto base station 21C stops radio wave output when the mobile station is not located in the adjacent femto cell 20B, and starts radio wave output in response to the mobile station handover from the femto cell 20A to the femto cell 20B. To do. The start of radio wave output of the femto base stations 21B and 21C may be triggered by the start of the handover process, may be triggered by the completion of the handover, or may be triggered by the execution of any process during the handover process. Good.

  Hereinafter, taking the femto base station 21B as an example, the configuration of the femto base station 21B and specific examples of the start and stop operations of the radio output of the femto cell 20B will be described. The femto base station 21C may be configured similarly to the femto base station 21B.

  FIG. 3 is a block diagram illustrating a configuration example of the W-CDMA femto base station 21B. In FIG. 3, an encoding unit 211 receives transmission data transmitted to a mobile station, performs channel coding (error correction coding), rate matching, interleaving, and the like to generate a transport channel and perform wireless communication. The data is supplied to the communication unit 212.

  The radio communication unit 212 adds the control information such as the TPC bit described above to the data sequence of the transport channel supplied from the encoding unit 111 to generate a radio frame of the physical channel, and maps to the QPSK signal point. Each process such as spread modulation, D / A conversion, quadrature modulation, frequency conversion to a radio frequency band, and signal amplification is performed. The radio communication unit 112 outputs a downlink signal (a radio signal transmitted from the base station to the mobile station) generated by these processes to the antenna 213.

  The radio communication unit 212 also receives an uplink signal (a radio signal transmitted from the mobile station to the base station) received by the antenna 213, and performs signal amplification, frequency conversion, orthogonal demodulation, A / D conversion, and despreading. Each process such as QPSK demodulation is performed, and the obtained data series is supplied to the decoding unit 116.

  The decoding unit 214 performs processing such as deinterleaving, channel decoding, and error correction on the received data sequence, and outputs the restored data.

  The control signal receiving unit 215 receives the output control signal S1 transmitted from the RNC 41. The output control signal S1 is a signal for controlling the radio wave output of the femto base station 21B, that is, the start and stop of the output of the downlink signal including the common pilot channel and the like. The output control signal S1 indicates whether or not the mobile station is in the two femtocells 20A and 20C adjacent to the femtocell 20B generated by the femto base station 21B.

  The output control unit 216 controls the radio wave output of the wireless communication unit 212 based on the content of the output control signal S1. More specifically, the output control unit 216 causes the wireless communication unit 212 to start outputting a downlink signal when the output control signal S1 indicates the start of output. On the other hand, when the output control signal S1 indicates output stop, the output control unit 216 causes the wireless communication unit 212 to stop outputting the downlink signal.

  Subsequently, a specific example of the radio wave output start procedure and stop procedure of the femto base station 21B will be described below with reference to the flowcharts of FIGS. FIG. 4 is a flowchart showing a processing procedure of the RNC 41 when starting radio wave output of the femto base station 21B. In step S101, the RNC 41 recognizes the handover of the mobile station to the femtocell 20A that is an adjacent cell of the femtocell 20B. In step S102, the RNC 41 transmits an output control signal S1 indicating the start of radio wave output to the femto base station 21B.

  FIG. 5 is a flowchart showing an example of the processing procedure of the femto base station 21B at the start of radio wave output. In step S201, the control signal receiver 215 included in the femto base station 21B receives the output control signal S1 indicating the start of radio wave output. In step S202, in response to the output control signal S1 indicating the start of radio wave output, the output control unit 216 starts radio wave output of the wireless communication unit 212.

  FIG. 6 is a flowchart showing an example of a processing procedure of the RNC 41 when stopping the radio wave output of the femto base station 21B. In step S301, the RNC 41 recognizes that no mobile station is located in the femtocell 20B formed by the femto base station 21B and the femtocells 20A and 20C adjacent thereto. In step S302, the RNC 41 transmits an output control signal S1 indicating a radio wave output stop to the femto base station 21B.

  FIG. 7 is a flowchart illustrating an example of a processing procedure of the femto base station 21B when radio wave output is stopped. In step S401, the control signal receiving unit 215 included in the femto base station 21B receives the output control signal S1 indicating that the radio wave output is stopped. In step S402, the output control unit 216 stops the radio wave output of the wireless communication unit 212 in response to the output control signal S1 indicating the radio wave output stop.

  As described above, in the wireless communication system 1 according to the present embodiment, the start of the radio wave output of the femto base station 21B is determined according to the location status of the mobile station in the adjacent femtocell 20A. In addition, the stop of the radio wave output of the femto base station 21B is determined according to the location status of the mobile stations in the adjacent femtocells 20A and 20C. As a result, the femto base station 21B can efficiently output a radio wave according to a situation in which a handover of the mobile station to the femtocell 20B is expected.

  In the configuration example of FIG. 1, only the femtocell 20A is an entrance cell that can be handed over from the macro cell 10 that is an upper layer cell, and one route from the macro cell 10 to the femto cell 20B passes through the femto cell 20A. Only. However, a plurality of entrance cells may be provided. For example, when the femtocell 20C is an entrance cell in addition to the femtocell 20A, the start of radio wave output of the femtocell base station 21B is determined according to the location status of the mobile stations in the femtocells 20A and 20C. Good.

  Further, the start of radio wave output of the femto base station 21C may be determined according to the location status of the mobile station in the femtocell 20A that is the entrance cell, instead of the adjacent femtocell 20B.

  In the configuration example of FIG. 1, the macro base station 11 and the femto base stations 21A to 21C are managed by the common RNC 41. However, such a configuration is an example. For example, an RNC (not shown) different from the RNC 41 that manages the macro base station 11 may be arranged for the femto base stations 21A to 21C. In the case of such a configuration, for example, the output control signal S1 is transferred from the RNC 41 to the RNC (not shown) for the femto base stations 21A to 21C using the inter-RNC interface (lur interface), and the femto base station 21A May be transmitted to femto base stations 21B and C via RNC (not shown) for ˜21C.

<Embodiment 2 of the Invention>
In the first embodiment of the invention, the start and stop of the radio wave output of the femto base stations 21B and 21C are controlled based on the occurrence of a handover grasped by the RNC 41 and the status of the mobile stations in the femtocells 20A to 20C. An example is shown. However, it is also possible to grasp the location status of the mobile stations in the femtocells 20 </ b> A to 20 </ b> C using, for example, the position information of the mobile stations registered in the location register 43.

  FIG. 8 shows the overall configuration of the wireless communication system 2 according to the present embodiment. The wireless communication system 2 includes a server 50 connected to the core network 42 so that the location register 43 can be referred to. The server 50 refers to the location register 43 and detects whether or not the mobile station is in the femtocell 20A. When the number of mobile stations located in the femtocell 20A changes from zero to a finite value, the server 50 transmits an output control signal S1 indicating the start of radio wave output to the femto base station 21B. Also. When the number of mobile stations residing in the femtocells 20A to 20C changes from a finite value to zero, the server 50 transmits an output control signal S1 indicating a radio wave output stop to the femto base station 21B. The operation of the femto base station 21B that has received the output control signal S1 may be the same as that of the first embodiment.

<Third Embodiment of the Invention>
Embodiments 1 and 2 of the invention have shown configuration examples in which the RNC 41 that manages the femto base stations 21A to 21C is arranged in the network separately from the femto base stations 21A to 21C. However, the femto base station may have a built-in RNC function. In this embodiment, instead of the above-described femto base stations 21A to 21C, femto base stations 61A to 61C having an RNC function are used, and signal transfer between the femto base stations 61A to 61C is performed. An example of controlling the 61C radio wave output will be described.

  FIG. 9 shows an overall configuration of the wireless communication system 3 according to the present embodiment. In FIG. 9, a femto base station 61A is used instead of the femto base station 21A to form a femto cell 20A that is an entrance cell. Similarly, femto base stations 61B and 61C are used in place of femto base stations 21B and 21C, respectively, to form femto cells 20B and 20C in which handover is restricted.

  The femto base stations 61 </ b> A to 61 </ b> C are connected to the core network 42 of the cellular communication carrier via the gateway 45 via the IP network 44. The femto base stations 61 </ b> A to 61 </ b> C relay traffic between the mobile station (for example, the mobile station 31 </ b> A) and the core network 42 via the IP network 44. Further, the femto base stations 61B and 61C have a function of starting / stopping radio wave output according to the location status of the mobile station in the adjacent cell.

  FIG. 10 is a block diagram illustrating a configuration example of the femto base station 61B. Note that the femto base station 61C may be configured in the same manner as in FIG. In FIG. 10, the control signal receiving unit 615 receives the in-zone notification signal S2 transmitted from the femto base station 61A or 61C that forms an adjacent cell. The in-zone notification signal S2 is a signal for notifying the presence or absence of a mobile station in the cell formed by the own station. For example, the in-zone notification signal S2 generated by the femto base station 61A indicates the presence / absence of a mobile station in the femto cell 20A.

  The output control unit 616 performs wireless communication based on the presence notification signal S2 received by the control signal reception unit 615 and the presence status of the mobile station in the own cell (femtocell 20B) grasped by the RNC unit 617. The start and stop of the radio wave output of the unit 212 are controlled.

  The RNC unit 617 has an RNC (Radio Network Controller) function, and transmits radio parameters (for example, a used frequency, a spreading code, a common pilot channel transmission power, etc.) used by the radio communication unit 212 to the radio communication unit 212. Supply.

  Subsequently, a specific example of the radio wave output start procedure and stop procedure of the femto base station 61B will be described below with reference to the flowcharts of FIGS. FIG. 11 is a flowchart showing a processing procedure of the femto base station 61A when starting the radio wave output of the femto base station 61B. In step S501, the femto base station 61A recognizes the handover of the mobile station to the femtocell 20A. In step S502, the femto base station 61A transmits a location notification signal S2 indicating that the mobile station is in the area to the femto base station 61B.

  FIG. 12 is a flowchart illustrating an example of a processing procedure of the femto base station 61B at the start of radio wave output. In step S601, the control signal receiving unit 615 included in the femto base station 61B receives a location notification signal S2 indicating that the mobile station is in the area. In step S602, the output control unit 616 starts radio wave output of the wireless communication unit 212 in response to the location notification signal S2 indicating that the mobile station is in the range.

  FIG. 13 is a flowchart illustrating an example of a processing procedure of the femto base station 61B when radio wave output is stopped. In step S701, it is determined whether or not the presence notification signal S2 transmitted from the adjacent femto base stations 61A and 61C has been canceled. When the presence notification signal S2 is canceled (YES in step S701), in step S702, it is determined whether or not the mobile station is in the own cell (femtocell 20B). When it is determined that the mobile station is not located in the own cell (NO in step S701), in step 703, radio wave output of the wireless communication unit 212 is stopped.

<Other embodiments>
In the above-described first to third embodiments, a series of lower layer cells from the entrance cell to the destination cell are femtocells 20A to 20C, and these upper layer cells are macrocells 10, which is an example. That is, the cell radius of a series of lower layer cells and upper layer cells is not limited to typical cell radii of femto cells and macro cells.

  1, 8 and 9 show a configuration in which a series of lower layer cells (femtocells 20A to 20C) from the entrance cell to the destination cell are arranged in one upper layer cell (macrocell 10). However, such a configuration is an example, and for example, the femtocell 20A that is an entrance cell and the femtocell 20 that is a destination cell may be provided in separate upper layer cells.

  1, 8 and 9 show an example in which a plurality of lower layer cells from the entrance cell to the destination cell are arranged in a daisy chain, but such a configuration is an example. For example, in order to cover a desired area with a plurality of small cells, a plurality of lower layer cells may be arranged such that one lower layer cell is adjacent to other three or more lower layer cells. . In addition, a plurality of entrance cells may be provided in a plurality of lower layer cells, or a plurality of destination cells may be provided.

  A plurality of lower layer cells (femtocells 20A to 20C) hierarchized in the upper layer cell (macrocell 10) may be formed by a single sectorized base station. Further, the plurality of lower layer cells may be formed by antennas that are extended from the upper layer cell base station forming the upper layer cell. In this case, the antenna extended from the upper layer cell base station corresponds to the lower layer cell base station forming the lower layer cell.

  Moreover, although Embodiment 1-3 mentioned above demonstrated the radio | wireless communications system which has a hierarchical cell structure, the application destination of this invention is not limited to the radio | wireless communications system which has a hierarchical cell structure.

  Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention described above.

It is a block diagram of the radio | wireless communications system concerning Embodiment 1 of this invention. It is a figure which shows the example of a setting of the adjacent cell information in the radio | wireless communications system concerning Embodiment 1 of this invention. It is a block diagram which shows the structure of the femto base station concerning Embodiment 1 of this invention. It is a flowchart which shows the process sequence of the radio | wireless network control apparatus at the time of starting the electromagnetic wave output of a femto base station. It is a flowchart which shows the start procedure of the radio wave output by a femto base station. It is a flowchart which shows the process sequence of the radio | wireless network control apparatus at the time of stopping the electromagnetic wave output of a femto base station. It is a flowchart which shows the stop procedure of the radio wave output by a femto base station. It is a block diagram of the radio | wireless communications system concerning Embodiment 2 of this invention. It is a block diagram of the radio | wireless communications system concerning Embodiment 3 of this invention. It is a block diagram which shows the structure of the femto base station concerning Embodiment 3 of this invention. It is a flowchart which shows the procedure of the location notification signal by a femto base station. It is a flowchart which shows the start procedure of the radio wave output by a femto base station. It is a flowchart which shows the stop procedure of the radio wave output by a femto base station.

Explanation of symbols

1, 2, 3 Wireless communication system 10 Macro cell 11 Macro base stations 20A-20C Femto cells 21A-21C, 61A-61C Femto base stations 31A, 31B Mobile station 40 Radio access network (RAN)
41 Radio Network Controller (RNC)
42 Core network 43 Location register (LR)
44 IP network 45 Gateway (GW)
50 servers

Claims (11)

A first base station that forms a first cell and performs wireless communication with a mobile station located within the first cell;
A second base station that forms a second cell and performs wireless communication with a mobile station located in the second cell;
A radio communication system, wherein output of a radio signal from the first base station is started or stopped according to a location status of a mobile station in the second cell.   When the mobile station is located in the second cell, the radio signal output of the first base station is performed, and when the mobile station is not located in the second cell, the first base station The wireless communication system according to claim 1, wherein the wireless signal output is stopped. A hierarchical cell structure in which a lower layer cell group including at least the first and second cells is arranged in an upper layer cell;
The second cell is an entrance cell in which handover of a mobile station from the upper layer cell is permitted,
The first cell is configured such that the mobile station cannot be handed over from the upper layer cell, and handover from at least one cell included in the lower layer cell group is permitted. The wireless communication system according to claim 1 or 2, wherein the mobile station is reachable by a mobile station via the cell.   The radio communication system according to claim 3, wherein radio signal output of the first base station is started in response to a handover from the upper layer cell to the second cell.   The radio according to claim 1 or 2, wherein a radio signal output of the first base station is started in response to a handover of a mobile station from a third cell adjacent to the second cell to the second cell. Communications system.   The wireless communication system according to any one of claims 1 to 5, wherein the second cell is a cell adjacent to the first cell. A wireless communication unit that transmits and receives wireless signals to and from a mobile station;
A control signal receiving unit that receives a control signal generated according to the location status of a mobile station in a cell formed by another base station;
An output control unit for starting signal output of the wireless communication unit based on the control signal;
A base station comprising:   8. The base according to claim 7, wherein the control signal is communicably connected to the other base station via a network and is generated by a radio network controller that controls a handover to a cell formed by the other base station. Bureau.   The base station according to claim 7, wherein the control signal is generated by the other base station having a radio network control function for controlling a handover of a mobile station. A control method for a base station that is used in a radio communication system to form a first cell and perform radio communication with a mobile station,
Receiving a control signal generated in accordance with a status of a mobile station in a second cell included in the wireless communication system (a);
(B) starting or stopping output of a radio signal received by the mobile station based on the control signal;
A base station control method including:   In the step (b), the radio signal is output when a mobile station is present in the second cell, and the radio signal is output when a mobile station is not present in the second cell. The base station control method according to claim 10, wherein the base station is stopped.

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