JP6637910B2 - Moving cell base station and mobile - Google Patents

Description

  The present invention relates to a wireless communication device and a moving object including the wireless communication device.

  2. Description of the Related Art Conventionally, in-vehicle antennas for wireless communication devices such as mobile communication and broadcast reception mounted on a movable body such as a movable vehicle (automobile), are omnidirectional antennas in a horizontal plane such as a sleeve antenna (hereinafter referred to as “omni antennas”). (See, for example, Patent Documents 1 and 2).

  The reason that the omni antenna is often used is that the direction of a mobile body equipped with a wireless communication device and the direction of radio wave reception (transmission) such as mobile communication and broadcast reception change, This is because the distribution of the arrival direction (radiation direction) of the radio wave of mobile communication becomes almost uniform in all directions so that it can be approximated by the Jakes model. Further, for the same reason, spatial diversity for improving communication quality can be achieved in a shorter distance as compared with the case of a fixedly arranged base station such as a macrocell base station. For this reason, a space diversity configuration in which a plurality of omni antennas are provided as element antennas in a vehicle-mounted antenna mounted on a moving body is mainly used.

  However, when trying to use Doppler diversity for improving the communication quality accompanying the movement of the moving object equipped with the wireless communication device using the conventional omni antenna, the movement of the moving object equipped with the wireless communication device is accompanied by the movement of the moving object equipped with the wireless communication device. The Doppler frequency shift in the generated received signal of the wireless communication is widened (for example, twice as large as the maximum Doppler frequency), and the throughput of the wireless communication may be reduced.

A wireless communication device according to one embodiment of the present invention is a wireless communication device that can be mounted on a mobile object, and has directivity in a plurality of different directions with respect to a main movement direction in which the mobile object mainly moves. A plurality of directional antennas, a frequency shift detection unit that detects a plurality of Doppler frequency shifts corresponding to each of the plurality of directional antennas when the mobile body moves, based on a detection result of the plurality of Doppler frequency shifts, A plurality of signal processing units for processing at least one of a reception signal and a transmission signal via each of the plurality of directional antennas so as to compensate for the Doppler frequency shift.
In the wireless communication device, the plurality of directional antennas include a forward directional antenna having directivity directed in a main movement direction of the moving object, and a directivity directed in a direction opposite to the main movement direction of the moving object. The frequency shift detecting unit detects two Doppler frequency shifts corresponding to the front directional antenna and the rear directional antenna when the moving body moves, and performs the signal processing. The unit processes at least one of a reception signal and a transmission signal via the front directional antenna based on a detection result of the Doppler frequency shift corresponding to the front directional antenna so as to compensate for the Doppler frequency shift. A signal processing unit for a forward directional antenna, and a detection result of a Doppler frequency shift corresponding to the backward directional antenna. Zui, as to compensate for the Doppler frequency shift may have a signal processing unit for the rear directional antenna for processing at least one of the received signal and the transmitted signal via the rear directional antenna.
Further, in the wireless communication device, the plurality of directional antennas include a first side directional antenna having directivity on one side in a direction intersecting a main movement direction of the moving body; A second side directional antenna having directivity on the other side, and wherein the frequency shift detection unit is configured to control the first side directional antenna and the second side directional antenna when the moving body moves. Detecting two Doppler frequency shifts corresponding to the respective lateral directional antennas, wherein the signal processing unit performs the Doppler frequency shift based on a detection result of the Doppler frequency shift corresponding to the first lateral directional antenna; And a signal processing unit for a first side directional antenna that processes at least one of a reception signal and a transmission signal via the first side directional antenna so as to compensate for the second side directional antenna. Processing at least one of a reception signal and a transmission signal via the second side directional antenna based on a detection result of the Doppler frequency shift corresponding to the directional antenna so as to compensate for the Doppler frequency shift. A signal processing unit for the second side directional antenna.
In the wireless communication device, the signal processing unit may convert at least one frequency of the reception signal and the transmission signal based on a detection result of the Doppler frequency shift so as to compensate for the Doppler frequency shift. It may be.
Further, the wireless communication apparatus is a mobile base station that performs wireless communication of a backhaul line with a fixedly arranged base station of a mobile communication system, a mobile station that performs wireless communication with a base station of a mobile communication system, or A broadcast receiving device that receives a broadcast wave transmitted from a broadcast transmitting station may be used.
Further, the moving body to which the wireless communication device can be mounted may be a car, including a passenger car, a bus, a truck, or a motorcycle, a railroad vehicle running on a track, an aircraft, or a ship.

  A moving object according to another aspect of the present invention is a moving object including any of the wireless communication devices. The moving object may be an automobile including a passenger car, a bus, a truck, or a motorcycle, a railroad vehicle running on a track, an aircraft, or a ship.

  Advantageous Effects of Invention According to the present invention, it is possible to improve communication quality by using Doppler diversity while suppressing a decrease in throughput of wireless communication.

FIG. 1 is an explanatory diagram illustrating an example of a communication system including a wireless communication device (mobile base station) incorporated in a mobile object (automobile) according to an embodiment of the present invention. FIG. 3 is an explanatory diagram illustrating another example of the communication system according to the embodiment of the present invention. FIG. 4 is an explanatory diagram showing still another example of the communication system according to the embodiment of the present invention. FIG. 2 is a block diagram showing a configuration example of a base station device of a moving cell base station according to the embodiment. FIG. 9 is a block diagram showing another configuration example of the base station device of the moving cell base station according to the present embodiment. FIG. 9 is a block diagram showing still another example of the configuration of the base station device of the moving cell base station according to the embodiment. (A) is an explanatory view schematically showing a distribution (arriving wave distribution) of radio waves from a fixed base station arriving at a wireless communication device incorporated in a moving automobile according to a comparative example. (B) and (c) are explanatory diagrams each showing an example of a frequency distribution of a reception signal received by an omni antenna while the automobile incorporating the wireless communication device is stopped and moving. FIG. 3A is an explanatory diagram schematically showing a distribution (arriving wave distribution) of radio waves from a fixed base station arriving at a moving cell base station incorporated in a moving automobile according to the present embodiment. (B) is an explanatory view showing an example of a frequency distribution of a received signal received by a forward directional antenna and a backward directional antenna while the moving cell base station is moving. FIG. 2 is a block diagram showing a configuration example of a first wireless communication unit in a base station device of a moving cell base station having a Doppler diversity function according to the embodiment. FIG. 4 is a block diagram showing a configuration example of a second wireless communication unit in the base station device of the moving cell base station according to the embodiment. (A) is an explanatory view schematically showing a distribution (arriving wave distribution) of radio waves from a fixed base station arriving at a moving cell base station incorporated in a moving automobile according to another embodiment. (B) is an explanatory view showing an example of a frequency distribution of a received signal received by the side directional antenna while the moving cell base station is moving. (A) is an explanatory view schematically showing a distribution (arriving wave distribution) of radio waves from a fixed base station arriving at a moving cell base station incorporated in a moving automobile according to still another embodiment. (B) is an explanatory view showing an example of a frequency distribution of a received signal received by a forward directional antenna, a backward directional antenna, and a side directional antenna while the moving cell base station is moving. FIG. 11 is an explanatory diagram showing an example of a communication system including a wireless communication device (mobile station) incorporated in a mobile object (car) according to still another embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 are explanatory diagrams each showing an example of a communication system including a wireless communication device (mobile base station) incorporated in a mobile object according to an embodiment of the present invention. The communication system according to the present embodiment includes a fixed base station 20 connected to a cellular mobile communication network 10 and a mobile type as a wireless communication device mounted on an automobile (passenger car, truck, bus, etc.) 40 as a mobile body. (Hereinafter referred to as “moving cell base station”) 30 and a management device 60 that manages the moving cell base station 30. In the present embodiment, the case where the moving body is the automobile 40 will be described. However, the moving body in the present embodiment may be a railway vehicle, an aircraft, or a ship traveling on a track, in addition to the automobile. Also, in the communication system of FIG. 1, the fixed base station 20 is an example of a macro cell base station, but the fixed base station 20 may be a small cell base station or the like. The management device 60 may be configured by a computer device such as a single server, or may be configured so that computer devices such as a plurality of servers perform processing in cooperation with each other.

  In the communication system of FIG. 1, the moving cell base station 30 forms a mobile cell (hereinafter, referred to as a “moving cell”) 30A that covers at least an outer peripheral area of the automobile 40 and the inside of the automobile 40, and the moving cell 30A. A user apparatus 50 as a mobile station located in the cell 30A, a fixed base station 20, a user apparatus located in an area 20A covered by the fixed base station 20, or another base station installed in another mobile body. Relays communications between The moving cell 30 </ b> A may include a peripheral area outside the automobile 40 and an inside area of the automobile 40. The cell diameter of the moving cell 30A is, for example, 100 m, and may be 20 m or less to 50 m or less.

  The moving cell base station 30 includes a plurality of first antennas 311 for performing wireless communication between the base station device 300 and the fixed base station 20 or another moving cell base station 30 installed in another mobile body. 312, and a second antenna 315 that performs wireless communication with a user device 50 used by a general user of mobile communication in a moving cell 30A formed by the base station device 300. The first antennas 311 and 312 and the second antenna 315 are a main body of the automobile 40, for example, a front grille, a body rear portion, a bumper portion, a flat portion of a roof, a shark antenna portion at a rear portion of a roof in which antennas for other applications are incorporated, Or it is provided in the pillar portion. The first antennas 311 and 312 and the second antenna 315 may be shared antennas.

  The first antennas 311 and 312 are a plurality of directional antennas having unidirectionality in a plurality of directions different from each other based on a main movement direction in which the automobile 40 mainly moves. In the illustrated example, one of the plurality of first antennas 311 and 312 is a front directional antenna having a directivity directed to the front direction F which is the main movement direction of the automobile 40, and the other. The first antenna 312 is a backward directional antenna having a directivity directed in a rearward direction B which is opposite to the main moving direction of the automobile 40. Each of the first antennas 311 and 312 may be configured by a planar antenna such as a patch antenna or a microstrip antenna.

  Further, the first antennas 311 and 312 may have a beam forming function using a plurality of antenna elements. Further, in the present embodiment, an omni antenna is used as the second antenna 315, but the second antenna 315 may be composed of a front directional antenna and a rear directional antenna, like the first antenna. In this case, the second antenna 315 may have a beam forming function capable of controlling the number and direction of the antenna beams.

  In FIG. 1, a base station device 300 is installed, for example, in a trunk of an automobile 40, inside a dashboard, below a seat, or the like. The base station apparatus 300 may include a power supply (battery) in its own apparatus, or may receive power supply from a battery on the automobile 40 side. When power is supplied from the battery on the side of the vehicle 40, the supply of power from the battery to the base station device 300 is performed for a predetermined time (for example, one hour) from the driving stop (OFF) of the vehicle 40 in which charging of the battery is stopped. May be automatically stopped when elapses.

  In the communication system of FIG. 1, the moving cell base station 30 may have a repeater function that functions as a wireless relay station of the fixed base station 20. The moving cell base station 30 is assigned base station identification information (cell ID) that can be identified from other base stations, and can be connected to the backhaul line of the mobile communication network 10 via the fixed base station 20. It may have a function.

  FIG. 2 shows that a moving cell base station 30 mounted on an automobile 40 performs communication between a user equipment 50 and a satellite base station 22 as a fixed base station that communicates with the ground via a satellite station (artificial satellite) 20. 3 is a configuration example of a communication system for relaying.

  Also, FIG. 3 shows that a moving cell base station 30 mounted on an automobile 40 has a fixed base station 25 that communicates with the ground via a mooring balloon relay station (wireless relay station) 24 provided at a mooring balloon 23, 2 is a configuration example of a communication system that relays communication with a device 50.

4 to 6 are block diagrams each illustrating a configuration example of the base station device 300 of the moving cell base station 30 according to the present embodiment.
In FIG. 4, base station apparatus 300 of moving cell base station 30 is configured to be installable in automobile 40, and is installed in fixed base station 20 or another base installed in another mobile body via first antennas 311 and 312. A first wireless communication unit 302 that performs wireless communication with the station device, a second wireless communication unit 304 that performs wireless communication with the user device 50 via the second antenna 315, and a relay control unit 306. Prepare. The relay control unit 306 forms the moving cell 30A at least in a peripheral area outside the automobile 40, and the user apparatus 50 located in the moving cell 30A and the fixed base station 20 or another base station installed in another mobile body. The first wireless communication unit 302 and the second wireless communication unit 304 are controlled so as to relay communication with the device.

  The base station apparatus 300 may include a power supply (battery) in its own apparatus, or may receive power supply from the battery 41 of the automobile 40 as shown in FIG. In this case, the power supply from the battery 41 to the own base station apparatus is performed by the key OFF (stop of driving) of the automobile 40 in which the charging of the battery 41 is stopped so that the remaining charge capacity of the battery 41 does not fall below the predetermined capacity. May be controlled so as to automatically stop when a predetermined time (for example, one hour) has elapsed from the start. The time until the automatic stop may be set based on the remaining charge of the battery 41 or the like.

  In the moving cell base station 30, the frequency band used for wireless communication with the fixed base station 20 and the frequency band used for wireless communication with the user device 50 may be different from each other. For example, as a frequency band used for wireless communication with the fixed base station 20, a 28 GHz band, a 5 GHz band, or a 4.2 GHz band used in the fifth generation mobile communication system is used, and the wireless communication with the user apparatus 50 is performed. A 2.6 GHz band, a 700 MHz band, or a 2 GHz band may be used as a frequency band used for the above. By using different frequency bands as described above, the moving cell base station 30 reliably performs each wireless communication while avoiding interference between the wireless communication with the fixed base station 20 and the wireless communication with the user device 50. It can be carried out.

  In the base station apparatus 300 of the moving cell base station 30, the transmission power and the reception sensitivity of the first wireless communication unit 302 to the fixed base station 20 are higher than the transmission power and the reception sensitivity of the user apparatus 50 to the fixed base station 20. It may be configured as follows. In this case, in the cell boundary area of the cell 20A of the fixed base station 20 with which the user apparatus 50 can communicate and the out-of-service area near the cell boundary, the moving cell base station 30 has higher communication quality with the fixed base station 20. Communication is possible, and a moving cell 30A can be formed in the area. Accordingly, local offload of traffic can be reliably performed in the cell 20A of the fixed base station 20, and the area of mobile communication can be substantially expanded without increasing the number of fixed base stations 20. Also, the moving cell base station 30 may be connected simultaneously with the plurality of fixed base stations 20, set a plurality of lines, and increase the capacity of the line between the moving cell base station 30 and the fixed base station 20 ( Line capacity increase between a fixed base station group and a moving cell base station due to line aggregation by a plurality of fixed base station sites).

  Further, even in a mountain road or a parking lot at a mountain entrance where the radio wave intensity from the fixed base station 20 is weak, the vehicle is mounted on the automobile 40 running on the mountain path or the automobile 40 parked in the mountain entrance parking lot. The moving cell base station 30 can form a moving cell 30 </ b> A around the vehicle 40. Therefore, a user along a mountain trail or a user at a parking lot at a mountain entrance or in the vicinity thereof can use the mobile communication service via the moving cell base station 30.

  Relay control section 306 may control base station apparatus 300 to function as a wireless relay station (repeater). Further, the relay control unit 306 is assigned base station identification information (cell ID) that can be identified from other base stations, and performs control to connect to the backhaul line of the mobile communication network 10 via the fixed base station 20. It may be something.

  Further, the relay control unit 306 performs a first handover process accompanying the movement of the own station 30 with respect to the fixed base station 20 and a second handover process accompanying the relative movement between the own station 30 and the user device 50 as follows. May be configured to allow simultaneous parallel processing. For example, the relay control unit 306 performs a handover process of continuing the connection with the mobile communication network 10 by the own station 30 when the own station 30 moves across the cells 20A of the plurality of fixed base stations 20. When the user device 50 relatively moves with respect to 30, the control may be performed such that a handover process for continuing the connection with the mobile communication network 10 by the user device 50 is performed. By such a double handover process, even when the moving cell 30A is formed as the own station 30 moves, the connection of the user apparatus 50 located in the moving cell 30A to the mobile communication network 10 is cut off. Can be avoided.

  Further, relay control section 306 may control ON / OFF of moving cell formation by own station 30 or transmission power at the time of moving cell formation. This control is formed by, for example, the position information of the own station 30, the attitude information of the own station 30, the moving speed of the own station 30, and another base station device provided in the automobile 40 located around the own station 30. This may be performed based on at least one of the situation of the neighboring cells and control information from the outside. For example, the relay control unit 306 may control the ON / OFF of the moving cell formation or the transmission power at the time of the moving cell formation based on the control information received from the management device 60 via the mobile communication network 10. Here, the position information of the own station 30, the attitude information of the own station 30, the moving speed of the own station 30, and the like are determined by the GPS receiver and the azimuth sensor provided in the base station device 300 of the own station 30 and the main body of the automobile 40. The determination can be made based on the output or based on the location registration information of the own station 30.

  Further, in the communication system according to the present embodiment, the same frequency as the frequency used in the wireless communication with the user terminal 50 is not adjacent to the moving route (for example, the road) of the automobile 40 based on the arrangement of the fixed base station 20 and the like. A plurality of zones may be set as described above. The size of each zone is set to a size such that a plurality of moving cells can be arranged so as not to overlap each other. The length of each zone is, for example, 50 m to 1 km. Then, in a state where the plurality of zones are set, the relay control unit 306 performs wireless communication with the user device 50 using the frequency set in the zone where the own station 30 is located for each of the plurality of zones. It may be controlled so as to perform. For example, when the relay control unit 306 enters the vehicle 40 in any one of the plurality of zones, the relay control unit 306 wirelessly communicates with the user device 50 using a predetermined frequency set in the zone where the vehicle 40 has entered. Is controlled to be performed. By performing wireless communication with the user device 50 using a predetermined frequency for each zone in this manner, each zone can be regarded as a quasi-static cell, and the frequency of handover processing by the user terminal 50 is reduced. The burden can be reduced.

  Further, the second antenna 370 of the moving cell base station 30 may have a beam forming function, and the relay control unit 306 may control at least one of the direction and the number of beams formed by the second antenna 370. The control of the direction of the beam and the like is performed, for example, on the location information of the own station 30, the attitude information of the own station 30, the moving speed of the own station 30, and other information provided on a moving body such as an automobile located around the own station 30. And the control information from outside from the surrounding cells formed by the base station device. Here, the position information of the own station 30, the attitude information of the own station 30, the moving speed of the own station 30, and the like are determined by the GPS receiver and the azimuth sensor provided in the base station device 300 of the own station 30 and the main body of the automobile 40. The determination can be made based on the output or based on the location registration information of the own station 30. In particular, the relay control unit 306 forms beams in mutually different directions in cooperation with the own station 30 and other moving cell base stations mounted on other nearby vehicles in a parking lot or the like, thereby forming the own station. Control may be performed so that the station 30 and another moving cell base station form one cell. The cooperation control by the plurality of moving cell base stations can be performed, for example, based on control information received via the mobile communication network 10 from the management device 60 that manages the moving cell base stations. The control information is determined based on, for example, position information and attitude information of each moving cell base station.

  As shown in FIG. 6, the base station apparatus 300 includes a data processing unit 310 that processes data transmitted / received to / from the user apparatus 50, the fixed base station 20, or a base station of a nearby mobile unit. The processing unit 310 may be used for various purposes to cause the moving cell base station 30 to function as a movable local data center.

  For example, the data processing unit 310 provides information to be provided to the user device 50, the fixed base station 20, or a mobile base station device such as a nearby vehicle, and data of area information relating to an area where the vehicle 40 including the own station 30 is located. , Map information data of the area, data for navigation of the area, data for automatic driving of a moving object of the automobile 40 in the area, image data of a still image or a moving image taken by the automobile 40, and a moving object such as a nearby automobile. Image data of a still image or a moving image photographed in the above, image data of a still image or a moving image photographed by a base station device provided in a moving body such as a nearby automobile, and the user device 50 connected to the own station 30 May be generated and stored in the storage unit 308 or read from the storage unit 308. In this case, the relay control unit 306 transmits the at least one data in response to a request from the user device 50, the fixed base station 20, or a base station device of a nearby mobile unit or autonomously, Control is performed so as to transmit or receive data to or from a mobile base station device such as 20 or a nearby automobile.

  By having the data processing unit 310 and the relay control unit 306 configured as described above, the moving cell base station 30 can transmit area information downloaded from a server on the mobile communication network 10 side to a user who is located in the moving cell 30A. The area information may be transmitted to the device 50, or may be received by the user device 50 or the vehicle 40 itself and stored in the own station 30 or uploaded to a server on the mobile communication network 10 side. The moving cell base station 30 transmits detailed navigation data and automatic driving data of the peripheral area downloaded from the server on the mobile communication network 10 side to the automobile 40 functioning as the user device 50 located in the moving cell 30A. May be transmitted to the navigation system or the automatic driving system. In addition, the moving cell base station 30 receives information such as a peripheral road for data for navigation and data for automatic driving that the user device 50 or the body of the automobile 40 independently acquires, and stores the information in the own station 30, It generates navigation data or automatic driving data based on the received information or uploads the received information or the generated navigation data or automatic driving data to a server on the mobile communication network 10 side. Is also good.

  Further, the data is data to be transported via the movement of the automobile 40 equipped with the own station 30 (for example, data of large volumes of books and movies purchased on the Internet or the like that does not require urgency). You may. In this case, the data processing unit 310 stores and reads the data to be transported between the user device 50, the fixed base station 20, and a mobile base station device such as a nearby automobile in the storage unit 308. In addition, the relay control unit 306 transmits the data to be transported in response to a request from the user device 50, the fixed base station 20, or a base station device of a nearby mobile or autonomously, to the user device 50, the fixed base station 20, In response to a request from the user device 50, the fixed base station 20, or a base station of a nearby mobile unit, after the vehicle 40 including the own station 30 has received from the base station of the nearby mobile unit and has moved to a predetermined position. Or autonomously, the data to be transported is controlled to be transmitted to the user device 50, the fixed base station 20, or the base station device of a nearby mobile body. According to the above control, for example, large volumes of non-urgent book or movie data can be transported to a predetermined destination without passing through the mobile communication network 10, so that the load on the mobile communication network 10 is suppressed. can do.

  The transportation of the data may be performed by one automobile 40 equipped with the moving cell base station 30 or a plurality of automobiles 40 equipped with the moving cell base station 30 may sequentially transfer the transportation in cooperation with each other. It may be performed. The data transfer between the plurality of vehicles 40 may be performed by direct communication between the moving cell base stations 30 mounted on each of the plurality of vehicles 40 or may be performed by communication via the fixed base station 20.

  In the base station device 300 of the moving cell base station 30 shown in FIGS. 4 to 6, the first wireless communication unit 302 is configured by a terminal device (including a control device and a data modulation / demodulation device) paired with the fixed base station 20. , The second wireless communication unit 304 may be configured with a base station device similar to the base station device of the fixed base station 20.

  Next, the Doppler diversity function of the moving cell base station 30 mounted on the automobile 40 in the communication system having the above configuration will be described.

  FIG. 7A is an explanatory diagram schematically showing a distribution (arriving wave distribution) of a radio wave from a fixed base station arriving at a wireless communication device incorporated in a moving automobile 40 according to a comparative example. . FIGS. 7B and 7C show examples of the frequency distribution of a reception signal received by an omni antenna (omni antenna) 319 while the vehicle incorporating the wireless communication device is stopped and moving, respectively. FIG. A circle 900 shown by a dashed line in FIG. 7A represents a radio wave transmitted from a fixed base station which reaches the radio communication device of the automobile 40 when the radio propagation is approximated by the Jakes model of classical mobile communication propagation theory. It is a scattering ring. A black circle 909 distributed on the scattering ring 900 is a scattering point that emits a radio wave received by the omni antenna 319 of the wireless communication device of the automobile 40. Since the omni antenna 319 has a circular omnidirectional characteristic 319A centered on the antenna in a horizontal plane, the omni antenna 319 receives radio waves arriving from all the scattering points 909 on the scattering ring 900. In addition, the intensity of radio waves arriving from each scattered point 909 in all directions on the scattering ring 900 becomes almost uniform. The phenomenon that the intensity of radio waves arriving from all directions becomes almost uniform like the arriving wave distribution that can be approximated to the Jakes model has been confirmed not only in urban areas where there are many buildings such as buildings that reflect and scatter radio waves, but also in suburbs. I have.

2. Description of the Related Art Conventionally, omni antennas such as sleeve antennas are frequently used in in-vehicle antennas such as car phones. This is due to the fact that the arrival wave distribution around a moving object such as an automobile equipped with a wireless communication device is substantially uniform from all directions based on the Jakes model as described above. Further, for the same reason, spatial diversity for improving communication quality can be achieved in a shorter distance as compared with the case of a fixedly arranged base station such as a macrocell base station. For this reason, a space diversity configuration in which a plurality of omni antennas are provided as element antennas is mainly used in a conventional in-vehicle antenna mounted on a moving body such as an automobile. However, as shown below, when the omni-antenna is used, the frequency spread Δf _D due to the frequency shift due to the Doppler effect (hereinafter referred to as “Doppler frequency shift”) is twice the maximum Doppler frequency shift f _D , and There are problems that the communication throughput may be reduced and that the operation of the receiving circuit and the received signal may be complicated.

For example, when the automobile 40 is stopped, the frequency of the received signal 910 that is received when the radio wave transmitted from the fixed base station reaches the omni antenna 319 via each scattering point 909 is as shown in FIG. becomes the center frequency f _C of the radio wave transmitted from the fixed base station as shown in. Further, during the movement of the vehicle 40 moving in the forward direction F, as shown in FIG. 7C, the vehicle 40 moves from the scattering point located in the forward direction F, which is the moving direction of the vehicle 40, to the vehicle 40 due to the Doppler effect. frequency of the received signal of a radio wave toward the + f _D only shifted, the frequency of the radio wave of the received signal toward the motor vehicle 40 from the scattering point located in the rear direction to the moving direction of the automobile 40 is a reverse direction shifted by -f _D . As a result, the spread Δf _D of the frequency f _C due to the Doppler frequency shift of the received signal 919 received by the omni antenna 319 becomes twice (2f _D ) the maximum Doppler frequency shift f _D.

  Since the scattering at each scattering point 909 on the scattering ring 900 of the Jakes model is a different scattering process, the correlation between branches (individual receiving systems) that individually receive the radio waves scattered at the plurality of scattering points 909. Is extremely low.

Therefore, in the present embodiment, in order to solve the above-described problem, attention is paid to the fact that the scattering at each scattering point 909 on the scattering ring 900 of the Jakes model is a different scattering process, and the scattering at a plurality of different scattering points is different. With a configuration having a plurality of individual receiving systems (hereinafter, referred to as “diversity branches”) to which a unidirectional antenna is assigned for each Doppler frequency shift of the extracted radio wave, the spread Δf _D of the frequency f _C due to the Doppler frequency shift is obtained. A circuit size is small and an effective diversity effect is obtained while suppressing a decrease in throughput. In particular, in the present embodiment, the Doppler frequency shift of the received signal received in each diversity branch is shifted from the center frequency f _{C of the} radio wave transmitted from the fixed base station in one direction (plus or minus direction). Therefore, in addition to the diversity effect, the demodulation processing of the received signal is easy, and the effect that the receiving circuit scale is small and high demodulation performance can be obtained is obtained.

  FIG. 8A is a diagram schematically illustrating a distribution (arriving wave distribution) of radio waves from the fixed base station 20 arriving at the moving cell base station 30 incorporated in the moving vehicle according to the present embodiment. FIG. FIG. 8B is an explanatory diagram showing an example of the frequency distribution of the reception signals 911 and 912 received by the forward directional antenna 311 and the backward directional antenna 312 while the moving cell base station 30 is moving. .

In the embodiment of FIG. 8, according to the Jakes model described above, the received signal of the arriving wave arriving from the forward direction F of the automobile 40 equipped with the moving cell base station 30 moving forward shifts to a higher frequency due to the Doppler effect. . Conversely, the received signal of the incoming wave arriving from the rear of the vehicle 40 shifts to a lower frequency due to the Doppler effect. Unidirectional antennas 311 and 312, which are spatial filters for exclusively receiving each of the incoming waves from the front and rear directions, are installed before and after the vehicle 40 to form a diversity branch. Since the frequency spread Δf _D of the arriving wave received by each diversity branch due to the Doppler frequency shift f _D is narrower than that of the comparative example as shown in FIG. 8B, demodulation of the received signal is easy. Thus, high demodulation performance is obtained with a small receiving circuit scale, and the receiving characteristics are improved.

  Although the example of FIG. 8 illustrates a case where a radio wave from the fixed base station 20 is received, the antennas 311 and 312 have a correlation between transmission and reception, so that a case where a radio wave is transmitted to the fixed base station 20 is also illustrated. There is a similar effect.

FIG. 9 is a block diagram illustrating a configuration example of the first wireless communication unit 302 in the base station device 300 of the moving cell base station 30 having the Doppler diversity function according to the present embodiment.
9, a first wireless communication unit 302 includes a first high-frequency signal processing unit 320A connected to a forward directional antenna 311, a second high-frequency signal processing unit 320B connected to a backward directional antenna 312, and a base. And a band processing unit 326. The first high-frequency signal processing unit 320A and the second high-frequency signal processing unit 320B respectively include a duplexer (DUP: Duplexer) 321A, B, a reception power amplifier 322A, B, a frequency shift detection unit 323A, B, It includes transmission power amplifiers 324A and 324B and frequency converters 325A and 325B.

Frequency shift detection unit 323A, B, respectively, for detecting a Doppler frequency shift _{f D} corresponding to the front directional antenna 311 and the rear directional antenna 312 during movement of the motor vehicle 40. The detection of the Doppler frequency shift f _D may be performed based on the reception result of the cell reference signals received from the fixed base station 20.

Further, each of the frequency conversion section 325A, B on the basis of the detection result of the Doppler frequency shift f _D, so as to compensate for the Doppler frequency shift f _D, through the respective front directional antenna 311 and the rear directional antenna 312 It functions as a signal processing unit that processes the reception signal and the transmission signal. For example, the frequency converting unit 325A, respectively of B, based on the detection result of the Doppler frequency shift f _D, converts the frequency of the received signal and the transmitted signal so as to compensate for the Doppler frequency shift f _D.

In this example, the frequency converting unit 325A on the basis of the detection result of the Doppler frequency shift _{f D,} the frequency _{f R (= f C + f} D of the received signal amplified by the received reception power amplifier 322A in the front directional antenna 311 ) Is shifted to the original frequency f _C, and the received analog signal of the high frequency f _C is further converted to a digital received signal R of a predetermined intermediate frequency and output to the baseband processing unit 326. The frequency conversion unit 325A converts the digital transmission signal T of the intermediate frequency received from the baseband processor 326 into an analog transmission signal of the high frequency of f _C, further, the detection result of the Doppler frequency shift f _D Based on this, the frequency of the transmission signal f _C is shifted and converted into a frequency f _T (= f _C −f _D ) and output to the transmission power amplifier 324A.

Further, in the present embodiment, the frequency conversion section 325B based on the detection result of the Doppler frequency shift _{f D,} the frequency _f R (= _{f C} of the received signal amplified by the received reception power amplifier 322B at the rear directional antenna 312 −f _D ) to the original frequency f _C , and further converts an analog reception signal of the high frequency f _C into a digital reception signal R of a predetermined intermediate frequency, and outputs it to the baseband processing unit 326. I do. The frequency converting unit 325B converts the digital transmission signal T of the intermediate frequency received from the baseband processor 326 into an analog transmission signal of the high frequency of f _C, further, the detection result of the Doppler frequency shift f _D Based on this, the frequency of the transmission signal f _C is shifted and converted to the frequency f _T (= f _C + f _D ) and output to the transmission power amplifier 324B.

The frequency conversion based on the detection result of the Doppler frequency shift f _D can be performed on either the received signal and the transmitted signal.

  The baseband processing unit 326 generates reception target data from the digital reception signal R received from the first high-frequency signal processing unit 320A and the second high-frequency signal processing unit 320B, or generates the first data from the transmission target control data. Various processes for generating a digital transmission signal T to be transmitted to the high-frequency signal processing unit 320A and the second high-frequency signal processing unit 320B are performed. For example, the baseband processing unit 326 includes a serial / parallel conversion unit (S / P), a parallel / serial conversion unit (P / S), a digital modulation unit, a digital demodulation unit, and the like. In the case of transmitting and receiving by Orthogonal Frequency Division Multiplexing (OFDM), the baseband processing unit 326 further includes a guard period (GI) removing unit, a digital Fourier transform (DFT) unit, and a guard period ( GI) insertion section, digital inverse Fourier transform (IDFT) section, and the like. Here, the modulation method and the demodulation method in the baseband processing unit 326 are not limited to specific ones.

  Further, the transmission method by the first wireless communication unit 302 may be a multi-carrier transmission method or a single-carrier transmission method.

FIG. 10 is a block diagram illustrating a configuration example of the second wireless communication unit 304 in the base station device 300 of the moving cell base station 30 having the Doppler diversity function according to the present embodiment.
10, the second wireless communication unit 304 includes a high-frequency signal processing unit 340 and a baseband processing unit 346 connected to the second antenna 315. The high-frequency signal processing unit 340 includes a DUP (Duplexer: duplexer) 341, a reception power amplifier 342, a transmission power amplifier 344, and a frequency conversion unit 345.

In the example of the second radio communication unit 304 in FIG. 10, but it does not include a frequency shift detector for detecting a Doppler frequency shift f _D, provided with a front directional antenna and the rear directional antenna as a second antenna 315, Like the above-described first wireless communication unit 302, a frequency shift detecting unit and a frequency converting unit for detecting a Doppler frequency shift f _D corresponding to each antenna are provided, and forward directivity is compensated for the Doppler frequency shift f _D. The received signal and the transmitted signal via the antenna and the backward directional antenna may be processed.

  As described above, according to the present embodiment, in the moving cell base station 30 mounted on the vehicle, the price can be reduced, and the communication quality is improved by using the Doppler diversity while suppressing the decrease in the wireless communication throughput. be able to.

  FIG. 11A schematically shows a distribution (arriving wave distribution) of radio waves from a fixed base station arriving at a moving cell base station 30 incorporated in a moving automobile 40 according to another embodiment. FIG. FIG. 11B is an explanatory diagram showing an example of a frequency distribution of a reception signal received by the side directional antennas 313 and 314 while the moving cell base station 30 is moving.

In the embodiment of FIG. 11, as described above, according to the Jakes model, the received signal of the arriving wave arriving from the front direction F of the automobile 40 equipped with the moving cell base station 30 moving forward has a higher frequency due to the Doppler effect. shift. Conversely, the received signal of the incoming wave arriving from the rear of the vehicle 40 shifts to a lower frequency due to the Doppler effect. In the present embodiment, unidirectional side directional antennas 313 and 314, which are spatial filters for exclusively receiving incoming waves from the left and right directions intersecting these forward and backward directions, respectively, are installed in the automobile 40. Diversity branch. Since the frequency spread Δf _D of the arriving wave received by each diversity branch due to the Doppler frequency shift f _D is narrower than that of the comparative example as shown in FIG. 11B, demodulation of the received signal is easy. Thus, high demodulation performance is obtained with a small receiving circuit scale, and the receiving characteristics are improved.

  Although the example of FIG. 11 illustrates a case where radio waves from the fixed base station 20 are received, the antennas 313 and 314 have a correlation between transmission and reception, and therefore, a case where radio waves are transmitted to the fixed base station 20 is also illustrated. There is a similar effect.

  FIG. 12A schematically shows a distribution (arriving wave distribution) of radio waves from a fixed base station arriving at a moving cell base station 30 incorporated in a moving automobile 40 according to still another embodiment. FIG. FIG. 12B shows an example of a frequency distribution of a reception signal received by the front directional antenna 311, the rear directional antenna 312, and the side directional antennas 313 and 314 while the moving cell base station 30 is moving. FIG.

In the embodiment shown in FIG. 12, unidirectional antennas 313 and 314, which are spatial filters for exclusively receiving incoming waves from the forward direction, the backward direction, and the left and right directions, respectively, are installed in the automobile 40 to form a diversity branch. Since the frequency spread Δf _D of the arriving wave received by each diversity branch due to the Doppler frequency shift f _D is narrower than that of the comparative example as shown in FIG. 12B, demodulation of the received signal is easy. Thus, high demodulation performance is obtained with a small receiving circuit scale, and the receiving characteristics are improved.

  Although the example of FIG. 12 illustrates a case where a radio wave from the fixed base station 20 is received, the antennas 313 and 314 have a correlation between transmission and reception. There is a similar effect.

  In the above embodiment, the case where the wireless communication device incorporated in the automobile 40 is the moving cell base station 30 has been described, but the wireless communication device incorporated in the automobile 40 may be a device other than the moving cell base station 30. Good. For example, according to the present invention, as shown in FIG. 13, a wireless communication device incorporated in an automobile 40 has a user apparatus (mobile station) having antennas 511 and 512 and a user apparatus main body 500 fixedly arranged with respect to the automobile 40. The same can be applied to the case of 50), and a similar effect can be obtained.

  Further, the present invention provides a broadcast system for receiving a broadcast wave transmitted from a broadcast transmitting station, wherein the wireless communication device incorporated in the vehicle has a broadcast receiving antenna fixed to the vehicle and a receiving device main body. The same can be applied to the case of a receiving device, and a similar effect can be obtained.

  Further, the processing steps described in this specification and the components of the communication system, the wireless communication device, the base station device, and the user device (mobile station device, user terminal device, mobile device) can be implemented by various means. it can. For example, these steps and components may be implemented in hardware, firmware, software, or a combination thereof. For example, the processing in the wireless communication device (base station device) according to the present embodiment is executed by reading a predetermined program into hardware described below, or executing a predetermined program pre-installed in hardware described later. This is achieved by doing

  Regarding hardware implementation, means such as a processing unit used for realizing the above steps and components in an entity (for example, various wireless communication devices, Node B, terminal, hard disk drive device, or optical disk drive device) include: One or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processors (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors , A controller, microcontroller, microprocessor, electronic device, other electronic unit designed to perform the functions described herein, a computer, or a combination thereof.

  Also, with respect to firmware and / or software implementation, any means such as a processing unit that may be used to implement the above components may include programs (eg, procedures, functions, modules, instructions, etc.) that perform the functions described herein. , Etc.). In general, any computer / processor-readable medium that explicitly embodies firmware and / or software code will be implemented by means of a processing unit or the like used to implement the above steps and components described herein. May be used to implement. For example, firmware and / or software code may be stored in a memory, for example, in a control device, and executed by a computer or a processor. The memory may be implemented inside a computer or a processor, or may be implemented outside a processor. The firmware and / or software code includes, for example, a random access memory (RAM), a read only memory (ROM), a nonvolatile random access memory (NVRAM), a programmable read only memory (PROM), and an electrically erasable PROM (EEPROM). ), A FLASH memory, a floppy disk, a compact disk (CD), a digital versatile disk (DVD), a magnetic or optical data storage device, etc. Good. The code may be executed by one or more computers or processors, and may cause the computers or processors to perform the functional aspects described herein.

  Also, descriptions of the embodiments disclosed herein are provided to enable one of ordinary skill in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

10 mobile communication network 20 fixed base station (macro cell base station)
20A Fixed base station cell (macro cell)
21 satellite stations (artificial satellites)
22 Fixed base station (satellite earth station)
23 Moored Balloon 24 Moored Balloon Relay Station 25 Fixed Base Station 30 Moving Cell Base Station (Mobile Base Station)
30A Moving cell 40 Automobile 41 Battery 50 User equipment (mobile station)
Reference Signs List 60 management device 300 base station device 302 first wireless communication unit 304 second wireless communication unit 306 relay control unit 308 storage unit 310 data processing unit 311 first antenna (forward directional antenna)
312 1st antenna (backward directional antenna)
313 First antenna (right-directional antenna)
314 1st antenna (left side directional antenna)
315 Second antenna 320A, B First and second high-frequency signal processing units 321A, B Duplexer (DUP)
322A, B Receive power amplifier 323A, B Frequency shift detector 324A, B Transmit power amplifier 325A, B Frequency converter 326 Baseband processor

JP 2008-079246 A JP-A-8-107379

Claims (8)

A moving cell base station that is mounted on a moving body and forms a mobile cell,
A first wireless communication unit that performs wireless communication of a first frequency with a fixed base station of a mobile communication system
A second wireless communication unit that performs wireless communication with a user device at a second frequency different from the first frequency;
A moving cell is formed in a peripheral area at least outside the moving object, and the first wireless communication unit and the second radio communication unit are configured to relay communication between a user apparatus located in the moving cell and the fixed base station. A relay control unit that controls the wireless communication unit;
The first wireless communication unit and the second wireless communication unit each
A plurality of directional antennas having unidirectionality in a plurality of directions different from each other with reference to a main moving direction in which the moving body mainly moves,
A frequency shift detection unit that detects a plurality of Doppler frequency shifts corresponding to each of the plurality of directional antennas when the moving body moves,
Based on the detection results of the plurality of Doppler frequency shifts, to compensate for the Doppler frequency shift, comprising a plurality of signal processing unit that processes a received signal and a transmission signal via each of the plurality of directional antennas, ,
Said plurality of directional antennas, the rear has a front directional antenna with unidirectional oriented in the main direction of movement of the moving body, the unidirectional to the main movement direction of the movable body facing the opposite direction oriented A directional antenna, a first lateral directional antenna having unidirectional directivity to one side in a direction intersecting the main moving direction of the moving body, and a monolateral antenna facing the other side of the moving body. A second side directional antenna having directivity; and
The frequency shift detection unit, corresponding to each of said front directional antenna during movement of the moving body, before Symbol rear directional antenna, said first side directional antenna and the second lateral directional antenna Detect four Doppler frequency shifts,
The signal processing unit,
On the basis of the detection result of the Doppler frequency shift corresponding to the forward directional antenna, so as to compensate for the Doppler frequency shift, for the forward directional antenna for processing the reception signal and the transmission signal via the forward directional antenna A signal processing unit;
Based on the detection result of the Doppler frequency shift corresponding to the backward directional antenna, to compensate for the Doppler frequency shift, for the backward directional antenna for processing the reception signal and the transmission signal through the backward directional antenna A signal processing unit ;
Before SL based on the detection result of the corresponding Doppler frequency shift in the first side directional antenna, the Doppler frequency shift to compensate the received signal through the first side directional antenna and the transmission signal A signal processing unit for a first lateral directional antenna that processes
Based on the detection result of the Doppler frequency shift corresponding to the second lateral directional antenna, the reception signal and the transmission signal via the second lateral directional antenna are compensated for the Doppler frequency shift. A signal processing unit for processing a second lateral directional antenna for processing. In the moving cell base station of claim 1 ,
The moving cell base station, wherein the signal processing unit converts frequencies of the reception signal and the transmission signal so as to compensate for the Doppler frequency shift based on a detection result of the Doppler frequency shift. In the moving cell base station according to claim 1 or 2 ,
The moving cell base station, wherein transmission power and reception sensitivity of the first wireless communication unit to the fixed base station are higher than transmission power and reception sensitivity of the user apparatus to the fixed base station. In the moving cell base station according to any one of claims 1 to 3 ,
A moving cell base station, comprising: a first handover process associated with a movement of the own station with respect to the fixed base station; and a second handover process associated with a relative movement between the own station and the user apparatus. In the moving cell base station according to any one of claims 1 to 4 ,
A moving cell base station, wherein the plurality of directional antennas of each of the first wireless communication unit and the second wireless communication unit have a beamforming function. In the moving cell base station according to any one of claims 1 to 5 ,
The moving cell base station, wherein the moving object is a car including a passenger car, a bus, a truck, or a motorcycle, a railcar running on a track, an aircraft, or a ship. Mobile comprise any of the moving cell base station of claims 1 to 5. The mobile object according to claim 7 ,
A moving object, which is a car including a passenger car, a bus, a truck, or a motorcycle, a railroad vehicle running on a track, an aircraft, or a ship.

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