JP5292021B2 - Mobile radio base station - Google Patents

Description

  The present invention relates to a mobile radio base station configured by mounting a base station represented by a femtocell on an engine-driven vehicle (automobile or the like).

  Conventionally, a simple base station called a femtocell that can be installed in a house or a store is known. A femtocell is an ultra-small base station connected to a cellular network via a general subscriber line. By using a femtocell, it is difficult to receive radio waves from an existing fixed base station. But you can make your mobile phone usable.

FIG. 10 is a diagram illustrating a conventional wireless communication system including a base station using femtocells. As shown in FIG. 10, a femtocell (simple base station) 300 is installed inside a building 301 where radio waves from an existing fixed base station are difficult to reach, and an IP network 303 via a wired broadband line 302 such as ADSL. To the existing mobile phone network 305 via the IP network 303 and the gateway 304. As a result, a wireless communication terminal (mobile phone) 306 within the femtocell area is connected to the mobile phone network 305 via the IP network 303 and can communicate even from inside the building 301 where radio waves from fixed base stations are difficult to reach. become.
For example, as shown in FIG. 11, a femtocell (simple base station) 300 includes a broadband line communication unit 310 for connecting to a mobile phone network 305 via a broadband line 302, a wireless communication terminal (mobile phone) 306, and a wireless It comprises a wireless communication unit 320 and an antenna 330 for connection, a CPU 340 for controlling operations of the broadband line communication unit 310 and the wireless communication unit 320, a RAM 350, a ROM 360, and the like.

As such a base station, for example, “mobile communication system and relay apparatus used in this system” (see Patent Document 1) and “mobile communication system, radio switching method, mobile base station, and portable terminal” (patent Focusing on communication at mobile base stations or mobile relay stations mounted on moving bodies such as trains and automobiles, a system that can be handed over between fixed base stations without disconnecting communication has been proposed. ing.
JP-A-9-84126 JP 2004-32155 A

The prior art described in Patent Document 1 and Patent Document 2 does not consider the connection of the wireless communication terminal when the mobile wireless base station stops functioning.
For example, a case where a femtocell is mounted on an engine-driven vehicle is assumed. In this case, the femtocell is configured to be connected to the broadband system wirelessly. In this case, since the mobile radio base station (mobile base station) using the femtocell is supplied with power from the engine-driven vehicle, for example, as shown in the flowchart of FIG. Is stopped, the transmission to the radio communication terminal is stopped, and the function as the mobile radio base station is stopped. In that case, for example, as shown in the sequence diagram of FIG. 13, a wireless broadband system via a mobile base station 300 in which a wireless communication terminal (portable terminal) 306 of a user who is on the engine-driven vehicle is mounted on the engine-driven vehicle. If the wireless communication terminal (mobile terminal) 306 suddenly loses sight of the fixed base station due to the suspension of the function of the mobile wireless base station, the communication cannot be maintained. Communication is cut off and out of service area. In that case, the user of the wireless communication terminal (mobile terminal) 306 whose communication has been disconnected searches for a fixed base station in the mobile phone network (system) around the local station and tries to reconnect to resume the call. However, it takes time to connect to the fixed base station.

  According to the present invention, a radio communication terminal connected to a mobile radio base station is handed over to a base station of a second communication system before the function of the mobile radio base station stops, and the radio communication terminal An object of the present invention is to provide a mobile radio base station that prevents a base station from being lost and temporarily out of service.

To achieve the above object, a mobile radio base station according to claim 1 of the present invention uses a first radio communication unit that performs radio communication with a base station of a first radio communication system, and a second radio communication system. A second wireless communication unit that wirelessly communicates with the wireless communication terminal that performs wireless communication via the second wireless communication unit, and a wireless communication terminal that performs wireless communication via the second wireless communication unit via the first wireless communication unit and the first wireless communication system. A control unit that controls to connect to the second wireless communication system, and controls to lower the transmission power of the second wireless communication unit upon receiving a notice of stoppage of power supply to the local station, and a battery And when the control unit receives a notice of stoppage of power supply to its own station, the control unit switches to power supply from the battery and performs control to reduce the transmission power of the second wireless communication unit. Features.

In order to achieve the above object, a mobile radio base station according to claim 2 of the present invention uses a first radio communication unit that performs radio communication with a base station of the first radio communication system, and a second radio communication system. A second wireless communication unit that wirelessly communicates with the wireless communication terminal that performs wireless communication via the second wireless communication unit, and a wireless communication terminal that performs wireless communication via the second wireless communication unit via the first wireless communication unit and the first wireless communication system. Control to connect to the second wireless communication system, and upon receiving a power supply stop notice to the local station, collect base station information of the second wireless communication system around the local station, A control unit that controls to transmit a handover instruction to the radio communication terminal via the second radio communication unit, and a battery, and the control unit receives a notice of stoppage of power supply to the local station. Power supply from the battery The switching, and controlling to lower the transmission power of the second wireless communication unit.

In the mobile radio base station according to claim 3 of the present invention, the control unit transmits base station information of the second radio communication system around the local station a predetermined number of times, or the second radio communication When there is no wireless communication terminal connected through the unit, the second wireless communication unit is controlled to stop transmission.

  According to the present invention, the radio communication terminal connected to the mobile radio base station is handed over to the base station of the second communication system until the function of the mobile radio base station stops, and the radio communication terminal It is possible to prevent the base station from being lost and temporarily going out of service.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a radio communication system including a mobile radio base station according to an embodiment of the present invention. As shown in FIG. 1, a mobile radio base station (hereinafter also referred to as a mobile base station) 120 according to the present invention includes a femtocell installed in an engine-driven vehicle (hereinafter referred to as a vehicle) 110 such as an automobile or a bus. 120. The mobile base station 120 is wirelessly connected to a wireless broadband base station 160 of a wireless broadband system (first wireless communication system) via a wireless broadband line 150, and the wireless broadband base station 160 includes an IP (Internet Protocol) network 170 and The mobile phone network system (second wireless communication system) 140 is connected via the gateway 180. As a result, the wireless communication terminal (mobile terminal) 130 within the femtocell area is connected to the mobile phone network 140 via the IP network 170 and has a higher communication speed than the fixed base station of the existing mobile phone network (system). High-speed communication is possible from the inside of the vehicle 110 using the broadband line. It is assumed that there is a fixed base station 190 of the second wireless communication system 140 around the mobile base station 120.

  In the wireless communication system shown in FIG. 1, for example, a wireless communication terminal (mobile terminal) 130 uses a code division multiple access (CDMA) system as a mobile phone network line, and a wireless broadband line 150 has 3 Wireless communication is performed by the LTE (Long Term Evolution) method, which is a wireless communication method called the 9th generation, or the WiMAX (World wide interoperability for Microwave Access) method. In the embodiment, for example, the wireless communication terminal (mobile terminal) 130 and the mobile base station 120 are connected by the CDMA system, and the mobile base station 120 and the wireless broadband base station 160 are connected by the LTE system or WiMAX. Connected in a manner.

  In an environment where the wireless communication terminal 130 possessed by the user is wirelessly connected to the mobile base station 120 when the user is in the vehicle 110, the mobile base station 120 stops functioning together with the engine stop of the vehicle 110. It is intended to prevent the wireless communication terminal 130 from losing sight of the mobile base station 120 and temporarily becoming out of service. Therefore, the femtocell 120 used as the mobile base station 120 in the present invention is connected to the battery of the vehicle 110, and when the vehicle 110 is notified of the stop of the power supply in response to the stop of the engine of the vehicle 110, the vehicle 110 By obtaining power from the battery and operating, it is possible to maintain the function as a mobile base station for a certain period, during which transmission power control (transmission power control 1, transmission power control 2, transmission power control 3 described later) )It can be performed. In addition, you may make it provide the battery which can be charged inside the femtocell 120 used as a mobile base station. In that case, by charging while the engine of the vehicle 110 is operating, power can be obtained from the rechargeable battery even when the engine of the vehicle 110 is stopped. Can be maintained.

  FIG. 2 is a block diagram showing a configuration example 1 of the femtocell 120 used as a mobile base station in the present invention. As shown in FIG. 2, the femtocell 120 of Configuration Example 1 includes an antenna 121 for wirelessly communicating with a wireless broadband base station 160 of a wireless broadband system (first wireless communication system) via a wireless broadband line 150, and Wireless communication unit (second wireless communication unit) for wireless communication with wireless broadband line communication unit (first wireless communication unit) 122 and wireless communication terminal 130 using second wireless communication system (mobile phone network system) 140 ) 123 and the antenna 124, a control unit (CPU) 125 for controlling the operation of the wireless broadband line communication unit 122 and the wireless communication unit 123, and a RAM (Random Access Memory). 26, and a ROM (Read Only Memory) 127. Note that the battery 128 may or may not be provided.

The CPU 125 performs various controls related to the mobile base station 120 based on software such as a control program stored in the ROM 127 and a program that defines various processing procedures, various data stored in the RAM 126, and the like.
At this time, the CPU 125 causes the wireless communication terminal 130 that is performing wireless communication via the second wireless communication unit 123 to transmit the second wireless communication system 140 via the first wireless communication unit 122 and the first wireless communication system 150. And a control unit that controls to reduce the transmission power of the second wireless communication unit 123 when receiving a notice of stoppage of power supply to the local station. In addition, the control unit may be configured to switch to power supply from the battery 128 provided in the femtocell 120 and to reduce transmission power of the second wireless communication unit 123 when receiving a notice of stoppage of power supply to the own station. "Control function" and "When receiving a notice of stoppage of power supply to the own station, the base station of the second wireless communication system 140 around the own station is switched to the power supply from the battery 128 provided in the femtocell 120. The function of collecting information and controlling it to be transmitted to the wireless communication terminal 130 via the second wireless communication unit 123 and “transmitting base station information of the second wireless communication system 140 around the local station a predetermined number of times” After that, or when there is no wireless communication terminal connected via the second wireless communication unit 123, the transmission of the second wireless communication unit 123 is stopped ”.
In addition, the femtocell 120 of the above configuration example 1 incorporates the above-described control unit into the “combination of the conventional femtocell (simple base station) 300 illustrated in FIG. 10 and an in-vehicle module having a wireless broadband communication function”. Configure.

  FIG. 3 is a diagram showing a configuration example 2 of the femtocell 120 used as a mobile base station in the present invention. The femtocell 120 of the configuration example 2 has a function of searching the femtocell 120 of the configuration example 1 shown in FIG. 2 for a base station of the second wireless communication system 140 around its own station, and a vehicle navigation system or the like. 2 is connected to the CPU 125 via the external interface 210 for the femtocell 120 of the configuration example 1 shown in FIG. In addition, the wireless communication unit (local station base station search) 220 and the antenna 230 are sequentially connected to the CPU 125, and further, the local station base station search function 127a is added in the ROM 127. The portion is configured in the same manner as the femtocell 120 of the configuration example 1 described above. The car navigation system 200 can be configured without it. In addition, the CPU 125 causes the wireless communication terminal 130 that is performing wireless communication via the second wireless communication unit 123 to the second wireless communication system 140 via the first wireless communication unit 122 and the first wireless communication system 150. When controlling to connect and receiving a notice of stoppage of power supply to the own station, the base station information of the second radio communication system 140 around the own station is collected and passed through the second radio communication unit 123. This corresponds to a control unit that controls transmission to the wireless communication terminal 130.

[Transmission power control 1 in mobile radio base station]
FIGS. 4 and 5 are a flowchart and a sequence diagram, respectively, showing transmission power control 1 executed in the mobile radio base station of the present invention.
First, in step S11 of FIG. 4, it is determined whether or not there is a power supply stop notice for the femtocell 120. If there is no power supply stop notice, the self-loop is repeated, and if there is a power supply stop notice, the process proceeds to step S12. . The determination of the presence or absence of the power supply stop notice is made based on whether or not the engine stop of the vehicle 110 is detected, for example. In step S12, the transmission power of the femtocell 120 is lowered. As a method for reducing the transmission power, for example, a method of reducing the transmission power by a predetermined percentage every predetermined time is used. Thereafter, in step S13, transmission to the wireless communication terminal 130 is stopped. Thereby, the femtocell 120 stops functioning as a mobile base station.

  In the sequence diagram of FIG. 5, the wireless communication terminal 130 that has been connected to and communicated with the mobile base station 120 before receiving the advance notice of the stop of power supply has the transmission power of the mobile base station 120 as a result of executing step S12 of FIG. Therefore, it decides a handover to the fixed base station 190 of the mobile phone network around its own station, sends a “disconnect request” to the mobile base station 120 and sends a “connection request” to the fixed base station 190, When “channel assignment” is received from the fixed base station 190, the mobile base station 120 is handed over to the fixed base station 190 until the transmission is stopped, and communication with the fixed base station 190 is started.

  According to this transmission power control 1, the femtocell 120 lowers the transmission power to narrow the area of the mobile base station 120, so that the base station of the second wireless communication system monitored (searched) by the wireless communication terminal 130 is obtained. It is possible to perform handover to the fixed base station 190 around the local station, which is a station, thereby preventing the radio communication terminal 130 from losing sight of the mobile radio base station and being temporarily out of service.

[Transmission power control 2 in mobile radio base station]
FIGS. 6 and 7 are a flowchart and a sequence diagram showing transmission power control 2 executed in the mobile radio base station of the present invention, respectively.
First, in step S21 of FIG. 6, it is determined whether or not there is a power supply stop notice for the femtocell 120. If there is no power supply stop notice, the self-loop is repeated, and if there is a power supply stop notice, the process proceeds to step S22. . The determination of the presence or absence of the power supply stop notice is made based on whether or not the engine stop of the vehicle 110 is detected, for example. In step S22, the fixed base station information of the second wireless communication system 140 around the local station is collected, and the collected fixed base station information of the second wireless communication system 140 around the local station is collected as the second wireless communication unit 123. The number of trials is set to 0 (number of trials = 0).

  In step S23, it is determined whether or not the number of connected wireless communication terminals of the femtocell 120 is 0. If the number of connected wireless communication terminals is not 0, the process proceeds to step S24. S24 and step S25 are skipped and the process immediately proceeds to step S26. In step S24, the radio communication terminal 130 connected to the femtocell 120 is instructed to perform handover, and the number of trials is increased by one (number of trials = number of trials + 1). In the next step S25, it is determined whether or not the number of trials has reached the preset number N, and until the number of trials reaches the preset number N, No in step 25-No in step S23-No in step S24-step When the loop of S25 is repeated and the number of trials reaches the preset number N, the process proceeds to step S26. In step S26, transmission to the wireless communication terminal 130 is stopped. Thereby, the femtocell 120 stops functioning as a mobile base station.

  In the sequence diagram of FIG. 7, the wireless communication terminal 130 that has been connected to and communicated with the mobile base station 120 before receiving the advance notice of the stop of power supply causes the mobile base station 120 to execute steps S <b> 21 to S <b> 23 of FIG. 6. Upon receiving a power supply stop notice, collect fixed base station information around its own station, and upon receiving a “handover instruction” sent based on the collected fixed base station information around its own station, hand over to the fixed base station 190 When the mobile base station 120 sends a “disconnect request” to the mobile base station 120 and sends a “connection request” to the fixed base station 190 and receives a “channel assignment” from the fixed base station 190, the mobile base station 120 stops transmitting. In the meantime, handover is performed to the fixed base station 190 and communication with the fixed base station 190 is started. Meanwhile, the mobile base station 120 confirms the presence / absence of a connected wireless communication terminal by executing step S23, and until the number of connected wireless communication terminals disappears (or a predetermined number of times), No-step S24-step S25-step S23 of step S23. The transmission is continued by repeating this loop, and the transmission is stopped after confirming that the number of connected wireless communication terminals has become 0 (or after a predetermined number of transmissions).

  According to this transmission power control 2, the mobile base station 120 monitors (searches) a fixed base station around its own station after receiving a notice of stoppage of power supply, and collects fixed base station information around its own station, The wireless communication terminal 130 monitors (searches) the fixed base station 190 in the vicinity of the own station, which is the base station of the second wireless communication system that is transmitted to the wireless communication terminal 130 and is not monitored (searched) by the wireless communication terminal 130. Therefore, it is possible to prompt the handover of the radio communication terminal 130 to the fixed base station 190, thereby preventing the radio communication terminal 130 from losing sight of the mobile radio base station and temporarily going out of service. .

[Transmission power control 3 in mobile radio base station]
FIGS. 8 and 9 are a flowchart and a sequence diagram, respectively, showing transmission power control 3 executed in the mobile radio base station of the present invention.
First, in step S31 in FIG. 8, it is determined whether or not there is a power supply stop notice for the femtocell 120. If there is no power supply stop notice, the self-loop is repeated, and if there is a power supply stop notice, the process proceeds to step S32. . The determination of the presence or absence of the power supply stop notice is made based on whether or not the engine stop of the vehicle 110 is detected, for example. In step S32, the fixed base station information of the second wireless communication system 140 around the local station is collected, and the collected fixed base station information of the second wireless communication system 140 around the local station is collected as the second wireless communication unit 123. The number of trials is set to 0 (number of trials = 0).

  In step S33, it is determined whether or not the number of connected wireless communication terminals of the femtocell 120 is 0. If the number of connected wireless communication terminals is not 0, the process proceeds to step S34, and if the number of connected wireless communication terminals is 0, step is performed. Steps S34 and S35 are skipped, and the process immediately proceeds to step S36. In step S34, the fixed base station information of the second wireless communication system 140 around the local station is collected, and the collected fixed base station information of the second wireless communication system 140 around the local station is collected as the second wireless communication unit 123. Then, the transmission power of the femtocell 120 is reduced and the number of trials is increased by one (number of trials = number of trials + 1). As a method for reducing the transmission power, for example, a method of reducing the transmission power by a predetermined percentage every predetermined time is used. In the next step S35, it is determined whether or not the number of trials has reached a preset number N. Until the number of trials reaches the preset number N, No in step 35-No in step S33-Step S34-step When the loop of S35 is repeated and the number of trials reaches a preset number N, the process proceeds to step S36. In step S36, transmission to the wireless communication terminal 130 is stopped. Thereby, the femtocell 120 stops functioning as a mobile base station.

  In the sequence diagram of FIG. 9, the wireless communication terminal 130 that has been connected to the mobile base station 120 and communicated before receiving the advance notice of power supply stop is indicated by the mobile base station 120 in step S <b> 32 -step S <b> 33 in FIG. Step S34-Step S35 No-Step S33 No-When the fixed base station information around the own station sent out by executing the loop of Step S34 is received, the handover to the fixed base station 190 is decided and the transmission power is lowered. When a “disconnect request” is sent to the mobile base station 120 and a “connection request” is sent to the fixed base station 190 and a “channel assignment” is received from the fixed base station 190, the mobile base station 120 is stopped until transmission stops. In the meantime, handover to the fixed base station 190 is started, and communication with the fixed base station 190 is started. Meanwhile, the mobile base station 120 confirms the presence / absence of the connected wireless communication terminal by executing step S33, and the step S33 No-step S34 until there is no connected wireless communication terminal or until the base station information is transmitted a predetermined number of times. -Step S35-Step S33 is repeated to continue transmission, and after confirming that the number of connected wireless communication terminals has become 0 (or after a predetermined number of transmissions), stop transmission.

  According to the function stop method 3, by performing the function stop method 1 and the function stop method 2 described above at the same time, the wireless communication terminal 130 is more reliably connected to the local station that is the base station of the second wireless communication system 140. It is possible to perform handover to a fixed base station 190 in the vicinity, thereby preventing the radio communication terminal 130 from losing sight of the mobile radio base station and temporarily going out of service.

In the present invention, when any of the transmission power control 1, transmission power control 2, and transmission power control 3 described above is performed, all wireless communication terminals connected to the mobile base station 120 are handed over in one trial. Is not limited. Therefore, in each method, transmission is stopped after confirming that there is no wireless communication terminal connected to the mobile base station 120 (number of connected wireless communication terminals = 0).
In addition, the monitor (search) of the fixed base station of the second communication system 140 in the vicinity of the above-described own station is sent to the server of the mobile phone network 140 via the wireless broadband line 150 based on the GPS information obtained from the car navigation system. The mobile base station 120 (that is, the femtocell 120) may have a function of monitoring (searching) a fixed base station of the second communication system 140 around the local station.

It is a figure which shows schematic structure of the radio | wireless communications system containing the mobile radio | wireless base station which concerns on one Embodiment of this invention. It is a block diagram which shows the structural example 1 of the femtocell used as a mobile base station in this invention. It is a block diagram which shows the structural example 2 of the femtocell used as a mobile base station in this invention. It is a flowchart which shows the transmission power control 1 performed in the mobile radio base station of this invention. It is a sequence diagram which shows the transmission power control 1 performed in the mobile radio base station of this invention. It is a flowchart which shows the transmission power control 2 performed in the mobile radio base station of this invention. It is a sequence diagram which shows the transmission power control 2 performed in the mobile radio base station of this invention. It is a flowchart which shows the transmission power control 3 performed in the mobile radio base station of this invention. It is a sequence diagram which shows the transmission power control 3 performed in the mobile radio base station of this invention. It is a figure which shows the conventional radio | wireless communications system containing the base station using a femtocell. It is a figure which illustrates the structure of the femtocell of the conventional radio | wireless communications system. It is a flowchart which shows the transmission power control performed in the femtocell of the conventional radio | wireless communications system. It is a sequence diagram which shows the transmission power control performed in the femtocell of the conventional radio | wireless communications system.

Explanation of symbols

110 Engine-driven vehicle (vehicle)
120 Mobile radio base station (mobile base station; femtocell)
121 antenna 122 wireless broadband communication unit (first wireless communication unit)
123 wireless communication unit (second wireless communication unit)
124 Antenna 125 CPU
126 RAM
127 ROM
128 battery 130 wireless communication terminal (mobile terminal)
140 Second wireless communication system (mobile phone network system)
150 First wireless communication system 160 Wireless broadband base station 170 IP network 180 Gateway 190 Fixed base station of second wireless communication system 200 Car navigation system 210 External interface 220 Wireless communication unit (search for surrounding base stations of own station)
230 Antenna

Claims (3)

A first wireless communication unit that wirelessly communicates with a base station of the first wireless communication system;
A second wireless communication unit that wirelessly communicates with a wireless communication terminal that uses the second wireless communication system;
Control is performed so that a wireless communication terminal that is performing wireless communication via the second wireless communication unit is connected to the second wireless communication system via the first wireless communication unit and the first wireless communication system. A control unit that controls to lower the transmission power of the second wireless communication unit upon receiving a notice of stoppage of power supply to the own station,
A battery, and
The control unit, when receiving a notice of stoppage of power supply to its own station, switches to power supply from the battery, and controls to reduce the transmission power of the second wireless communication unit Radio base station. A first wireless communication unit that wirelessly communicates with a base station of the first wireless communication system;
A second wireless communication unit that wirelessly communicates with a wireless communication terminal that uses the second wireless communication system;
Control is performed so that a wireless communication terminal that is performing wireless communication via the second wireless communication unit is connected to the second wireless communication system via the first wireless communication unit and the first wireless communication system. In addition, upon receiving a notice of stoppage of power supply to the own station, the base station information of the second radio communication system around the own station is collected and handed over to the radio communication terminal via the second radio communication unit A control unit that controls to transmit the instruction ;
A battery, and
The control unit, when receiving a notice of stoppage of power supply to its own station, switches to power supply from the battery, and controls to reduce the transmission power of the second wireless communication unit Radio base station. The control unit transmits the base station information of the second wireless communication system around the local station a predetermined number of times, or when there is no wireless communication terminal connected through the second wireless communication unit, the first 3. The mobile radio base station according to claim 2 , wherein control is performed so as to stop transmission of the two radio communication units.

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