wireless communication system

Abstract

To provide a radio communication system which can transmit uplink data from a mobile station in an area of another base station device by performing downlink data transmission that becomes a response only to the base station device that has performed uplink data transmission and not performing downlink data transmission to another base station device, and can improve data transmission efficiency in a system.SOLUTION: A radio communication system includes: a plurality of base station devices 3 which performs downlink transmission by using a same frequency; and a line control device 2 which controls the base station devices 3. The line control device 2 stores a use line of the base station device 3 when receiving uplink data from the base station device 3 and transmits downlink data as a response to the uplink data to the stored use line of the base station device 3. The radio communication system does not transmit the downlink data to the base station device 3 that does not need the response and can perform uplink data transmission from a new mobile station device 4.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a wireless communication device, and more particularly to a wireless communication system capable of improving data transmission efficiency within the system. [Background technology]

[0002] Description of the Prior Art In a general wireless communication system used in a commercial wireless system or the like, a plurality of base station devices have an inter-base station synchronization function and communicate using the same operating wave. In such a case, if the transmission timings of the multiple base station devices are misaligned, mutual interference may occur in an overreach area where the incoming waves from the multiple base station devices overlap, resulting in a blind zone.

[0003] Therefore, in a wireless communication system, it is necessary to synchronize the transmission start timings from a plurality of base station devices. For example, a line control device transmits a downlink transmission start instruction to each base station device, and each base station device starts transmission in accordance with the transmission timing included in the downlink transmission start instruction, thereby aligning the transmission timing of multiple base stations.

[0004] Furthermore, some conventional wireless communication systems perform data transmission by periodically notifying location information in addition to a general voice communication function. Specifically, when a mobile station periodically notifies its location information using uplink data transmission, a data server connected to the line control device stores the location information and transmits a response to the mobile station that sent the notification. The response is transmitted as downlink data transmission from the base station device to the mobile station via the line control device. At this time, as described above, all base station devices transmit downlink data at the same timing.

[0005] That is, base station devices that do not have the coverage area of ​​the target mobile station that is the destination of the response to the uplink transmission also simultaneously perform downlink transmission operations. Therefore, even if a new mobile station enters the area while the base station device is transmitting downlink data, the mobile station cannot transmit uplink data. This is because, particularly, a mobile station in a system using the SCPC (Single Channel Per Carrier) radio method cannot transmit while receiving, and cannot receive while transmitting.

[0006] In this way, in a system using inter-base station synchronization, all base station devices in the system perform downlink data transmission at the same timing, and therefore uplink data transmission from the mobile station cannot be performed during that time.

[0007] Generally, data transmission is used frequently but for short periods of time, while voice communication is used less frequently but for longer periods of time than data transmission. Therefore, it is necessary to process frequently used data transmissions efficiently without letting them accumulate within the system.

[0008] [Related Technology] Incidentally, conventional technologies relating to wireless communication systems include Japanese Patent Application Laid-Open No. 2020-022029 "Wireless communication system and wireless communication method" (Patent Document 1) and Japanese Patent Application Laid-Open No. 2015-144408 "Wireless communication system" (Patent Document 2).

[0009] Patent document 1 describes that a control device determines the direction of movement from the mobile station's location information, determines the base station to which the mobile station should move, and a line control device grants transmission rights to the base station to which the mobile station should move, causing it to send a signal to the mobile station.

[0010] Patent document 2 also describes that the line control device sets a frame number as the start timing frame number of downlink transmission, which is spaced apart from the transmission timing of the instruction to start downlink transmission by the maximum value of the transmission time between the line control device and multiple base stations. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2020-022029 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-144408 Summary of the Invention [Problem to be solved by the invention]

[0012] However, in conventional wireless communication systems, when transmitting downlink data in response to uplink data transmission, downlink transmission is performed at the same timing even if the base station device is not located in the area where the mobile station to which the response is to be sent is located.As a result, even if another mobile station enters the area, uplink data transmission cannot be performed, resulting in a problem of reduced data transmission efficiency.

[0013] Incidentally, Patent Documents 1 and 2 do not describe that the line control device stores the base station device used when transmitting uplink data from a mobile station, and when transmitting downlink data in response, selects the stored base station device to transmit the downlink data.

[0014] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a wireless communication system that can improve data transmission efficiency within the system by transmitting downlink data in response to an uplink data transmission only to a base station device that has transmitted uplink data, and not transmitting downlink data to other base station devices, thereby enabling uplink data transmission from a mobile station in the areas of other base station devices. [Means for solving the problem]

[0015] The present invention, which solves the problems of the above-mentioned conventional example, is a wireless communication system having a plurality of base station devices which perform downlink transmission using the same frequency and a line control device which controls the plurality of base station devices, wherein the line control device: corresponding to a plurality of base station devices, storing adjacent base stations whose communication areas partially overlap with those of the base station devices;When receiving uplink data from a base station device, the base station device stores the line used by the base station device, and transmits downlink data in response to the uplink data to the line used by the stored base station device. At this time, if there is no adjacent base station corresponding to the stored base station device, Stored base station device Only It is characterized by transmitting downstream data.

[0016] Further, the present invention provides a line control device comprising: When transmitting downlink data as a response to uplink data to the line used by the stored base station device, if there is an adjacent base station corresponding to the stored base station device, the adjacent base station is used in addition to the stored base station device. The line used too It is characterized by transmitting downstream data.

[0017] Furthermore, in the above-mentioned wireless communication system, the present invention is characterized in that, when transmitting downlink data, the line control device designates to each base station device to which the data is to be transmitted the timing at which each base station device will start transmitting the downlink data, the timing being the maximum transmission time between the line control device and the plurality of base station devices from the transmission timing of the downlink data.

[0018] Furthermore, in the wireless communication system of the present invention, the areas of the plurality of base station devices are arranged in a line or a plane. [Effects of the Invention]

[0019] According to the present invention, there is provided a wireless communication system having a plurality of base station devices that perform downlink transmission using the same frequency and a line control device that controls the plurality of base station devices, wherein the line control device: corresponding to a plurality of base station devices, storing adjacent base stations whose communication areas partially overlap with those of the base station devices; When receiving uplink data from a base station device, the base station device stores the line used by the base station device, and transmits downlink data in response to the uplink data to the line used by the stored base station device. At this time, if there is no adjacent base station corresponding to the stored base station device, Stored base station device Only Since this is a wireless communication system that transmits downlink data, base station devices other than the base station device that transmits the downlink data do not transmit downlink data and can transmit uplink data, and this has the effect of transmitting uplink data such as location information from a mobile station device that has newly entered the area of ​​another base station device, thereby improving the data transmission efficiency of the entire system.

[0020] According to the present invention, the line control device comprises: When transmitting downlink data as a response to uplink data to the line used by the stored base station device, if there is an adjacent base station corresponding to the stored base station device, the adjacent base station is used in addition to the stored base station device. The line used too Since the wireless communication system transmits downlink data, the same downlink data can be transmitted in areas where the areas of the stored base station device and adjacent base station devices overlap, thereby preventing the occurrence of blind spots and ensuring the reliability of communication services.

[0021] Furthermore, according to the present invention, in the wireless communication system, when transmitting downlink data, the line control device designates the timing at which each base station device will start transmitting the downlink data to each destination base station device, which is the timing that is the maximum transmission time between the line control device and the multiple base station devices from the transmission timing of the downlink data, and transmits the data.Therefore, the base station device transmitting the downlink data can start downlink transmission at the same transmission timing regardless of the difference in distance from the line control device, which has the effect of suppressing mutual interference between base stations and preventing the occurrence of blind zones. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is an explanatory diagram showing an example of the configuration of a wireless communication system. [Figure 2] FIG. 2 is an explanatory diagram showing the configuration of a line control device 2 of the present wireless communication system. [Figure 3] FIG. 2 is an explanatory diagram showing frame generation in a line control device 2 of the present wireless communication system. [Figure 4] 10 is an explanatory diagram showing the setting of the downlink transmission start timing in the wireless communication system. FIG. [Figure 5] FIG. 2 is a sequence diagram showing control of downlink transmission timing in the wireless communication system. [Figure 6] FIG. 1 is a sequence diagram showing downlink data transmission (1) relative to uplink data transmission in the wireless communication system. [Figure 7] FIG. 1 is an explanatory diagram showing the occurrence of a blind spot in the wireless communication system. [Figure 8]FIG. 10 is a sequence diagram showing downlink data transmission (2) in response to uplink data transmission in the wireless communication system. [Figure 9] FIG. 10 is an explanatory diagram showing an operation state when the number of adjacent base stations in the present wireless communication system is set to two. DETAILED DESCRIPTION OF THE INVENTION

[0023] An embodiment of the present invention will be described with reference to the drawings. [Outline of the embodiment] A wireless communication system (this wireless communication system) according to an embodiment of the present invention is a wireless communication system having a plurality of base station devices that perform downlink transmission using the same frequency, and a line control device that controls the base station devices.When the line control device receives uplink data from a base station device, it stores the line used by that base station device and transmits downlink data in response to the uplink data to the line used by the stored base station device.Downlink data is not transmitted to base station devices that do not require a response, and uplink data transmission from new mobile stations in the area of ​​that base station device is possible, thereby improving the data transmission efficiency of the entire system.

[0024] In addition, in this wireless communication system, when the line control device transmits downlink data in response to uplink data, it transmits the downlink data to the lines used by base station devices in areas adjacent to the area of ​​the base station device in addition to the lines used by the stored base station device.This prevents problems in areas where the areas of base station devices overlap, where uplink data and downlink data interfere with each other and create blind spots, and ensures that downlink data can be received normally throughout the area of ​​the stored base station device, ensuring the reliability of communication services.

[0025] [Configuration of this wireless communication system: Figure 1] The configuration of this wireless communication system will be described with reference to Fig. 1. Fig. 1 is an explanatory diagram showing an example of the configuration of this wireless communication system. As shown in FIG. 1, this wireless communication system is used, for example, as a business wireless system, and includes a command desk 1-1 to 1-n (sometimes referred to as command desk 1 when the individual command desks are not distinguished), a line control device 2, a plurality of base station devices 3-1 to 3-n (sometimes simply referred to as base station devices 3), and a data server 6, and a plurality of mobile station devices 4-1 to 4-n (sometimes simply referred to as mobile station devices 4) communicate with the command desk 1, the data server 6, and other mobile station devices 4 within the communication area of ​​the base station device 3.

[0026] The line control device 2 and each base station device 3 are equipped with a GPS antenna that receives GPS signals from GPS (Global Positioning System) satellites 7, and the line control device 2 and each base station device 3, and the base station devices 3 themselves, are time-synchronized.

[0027] Furthermore, each mobile station device 4 is connected to location information collection devices 5-1 to 5-n (sometimes simply referred to as location information collection devices 5) by wire. The location information collection device 5 receives GPS signals from GPS satellites 5 to acquire location information, and outputs the location information to the mobile station device 4 periodically or at the timing of a preset event (such as a change in the internal state). The location information collection device 5 may be provided inside the mobile station device 4.

[0028] Each part of this wireless communication system will now be described. The command desk 1 is connected to the line control device 2 and is a device that controls this wireless system. The command desk 1 may also monitor and control multiple systems in an integrated manner. The command desk 1 also communicates with the mobile station devices 4 to give instructions and manage operations.

[0029] The line control device 2 is connected to the command console 1 and a plurality of base station devices 3 via wired lines, and performs line control and call control in this wireless communication system. In addition, by capturing GPS data from GPS satellites 7, the timing of wireless transmission in this system is adjusted.

[0030] Furthermore, as will be described later, when the line control device 2 of this wireless communication system receives uplink data from a base station device 3, it stores the base station device 3, and when transmitting downlink data in response, it controls the transmission to occur only over the line used by the stored base station device 3. The operation of the line control device 3 will be described later. The base station device 3 is connected to the line control device 2 by wire and to the mobile station device 4 by wireless. As described above, the base station device 3 also receives GPS data and adjusts the timing of wireless transmission.

[0031] The mobile station device 4 is a vehicle-mounted or portable wireless communication terminal, and can be operated in a mobile state or in a fixedly installed state. The mobile station device 4 performs wireless communication with the base station device 3 within the service area (communication area) of the base station device 3. Furthermore, the mobile station device 4 transmits the location information received from the location information collection device 5 to the data server 6 via the base station device 3 and the line control device 3 .

[0032] The GPS satellites 7 are satellites based on a general GNSS (Global Navigation Satellite System) that transmit signals with time information from multiple positioning satellites and enable measurement of the current position on the ground, etc.

[0033] [Configuration of line control device 2: Figure 2] Next, the configuration of the line control device 2 of this wireless communication system will be described with reference to Fig. 2. Fig. 2 is an explanatory diagram showing the configuration of the line control device 2. As shown in FIG. 2, the line control device 2 includes a frame generation unit 21, a control unit 22, a base station interface unit 23, and a GPS antenna 24. The line control device 2 is connected to a plurality of base station devices 3 (only one is shown here) and a data server 6. Furthermore, the line control device 2 is connected to a higher-level command desk 1, which is not shown here.

[0034] The frame generation unit 21 includes a GPS module 211, a PLL (Phase Locked Loop) unit 212, and a superframe counter 213, and generates a radio frame. The generation of radio frames and superframes will be described later.

[0035] The control unit 22 includes a CPU 221 and controls the entire line control device 2 . In particular, in the operation of this wireless communication system, when an uplink transmission message including the location information of a mobile station 4 is input from a base station device 3, the control unit 22 stores the line used by the base station device 3. The base station device 3 that performs the uplink transmission has a mobile station device 4 within its area. On the other hand, there is no mobile station device 4 within the area of ​​a base station device 3 that has not performed the uplink transmission at that time. When a downstream transmission is made in response to the upstream transmission, the downstream transmission message is output to the stored line used by the base station device 3.

[0036] As a result, in this wireless communication system, only base station devices 3 that have the mobile station device 4, which is the destination of the response, in their coverage area perform downlink transmission. Base station devices 3 that do not have the mobile station device 4 in their coverage area and do not need to respond do not perform downlink transmission, so that such base station devices 3 are able to perform uplink transmission. When a new mobile station device 4 enters the area of ​​a base station device 3 that is not performing downlink transmission, location information can be immediately reported by uplink transmission, thereby improving the efficiency of data transmission.

[0037] In addition, the control unit 22 of the line control device 2 of this wireless communication system stores the arrangement of base station devices 3 within the system, and for each base station device 3, also stores information on other base station devices 3 that are adjacent to the base station device 3 and whose communication areas partially overlap. As will be described later, the information on the adjacent base station devices 3 is used when performing downlink transmission in response to uplink transmission.

[0038] Furthermore, as in the conventional case, when a telegram for downlink transmission is input from the command console 1 or the like, the control unit 22 of the line control device 2 adds information instructing the timing of starting downlink transmission to the plurality of base station devices 3, and transmits a downlink transmission start instruction. The downlink transmission start instruction will be described later.

[0039] The base station interface unit 23 is an interface that connects to the base station device 3 . The GPS antenna 24 receives signals from a plurality of GPS satellites and outputs the received GPS signals to the GPS module 211 . The GPS module 211 outputs a 10 MHz clock signal and a 1 PPS (Pulse Per Second) signal based on a signal received by the GPS antenna 24. The 1 PPS signal is a square wave signal with a cycle of 1 second that indicates the timing of ticking seconds.

[0040] [Frame generation in line control device 2: Figure 3] Next, frame generation in the frame generation unit 21 of the line control device 2 will be described with reference to Fig. 3. Fig. 3 is an explanatory diagram showing frame generation in the line control device 2. As shown in FIG. 3, the GPS module 211 of the frame generating unit 21 outputs a 10 MHz clock signal and a 1 PPS signal. The PLL unit 212 outputs a 40 ms signal indicating frame timing every 40 ms based on the 10 MHz clock signal.

[0041] Based on the 40 ms signal output from the PLL unit 212 and the 1 PPS signal output from the GPS module 211, the super frame counter 213 assigns a frame number that identifies a wireless frame with a frame length of 40 ms at each frame timing (40 ms period) and notifies the CPU 221 of the control unit 22. Here, one superframe (720 ms) is defined as 18 radio frames (40 ms x 18).

[0042] At this time, the superframe counter 213 assigns each radio frame a frame number from "1" to "18" that indicates its position (order) within the superframe. The frame numbers are assigned using a frame counter that is incremented (+1) every 40 ms signal period. This frame counter synchronizes with the 1PPS signal every 3 minutes (180 seconds: 250 superframes) (the figure states "generate 1 superframe based on the 1PPS signal"). The frame number generated by the super frame counter 213 is notified to the CPU 221 of the control unit 22 at each frame timing of a 40 ms cycle.

[0043] [Downstream transmission start timing setting: Figure 4] Next, the setting of downlink transmission start timing for a plurality of base station devices 3 by the control unit 22 of the line control device 2 will be described with reference to Fig. 4. Fig. 4 is an explanatory diagram showing the setting of downlink transmission start timing in this wireless communication system. FIG. 4 also shows the relationship between the timing signal generated from the GPS received signal and the frame generation.

[0044] As shown in Fig. 4(a), the GPS module 211 of the line controller 2 acquires and outputs a 1PPS signal from a GPS received signal. Fig. 4(b) shows an enlarged view of one period (one second) of the 1PPS signal. As shown in FIG. 4(c), one superframe is made up of 18 radio frames of 40 ms each, and one period of the 1PPS signal includes the first to seventh radio frames of the next superframe.

[0045] Then, when the control unit 22 of the line control device 2 receives a downstream transmission instruction from the command console 1, for example, it transmits a downstream transmission start instruction (downstream transmission start message) to the plurality of base station devices 3, specifying the timing of starting downstream transmission. At this time, the control unit 22 specifies the timing for transmitting the downlink transmission start instruction by adding at least the maximum transmission time between the line control device 2 and the base station device 3. Here, the frame number for transmitting the downlink transmission start instruction is referred to as the transmission timing definition frame number.

[0046] Specifically, the control unit 22 sets a frame number that is spaced apart from the transmission timing specification frame number by the number of frames corresponding to the maximum transmission time as the transmission timing frame number at which multiple base station devices 3 start downlink transmission simultaneously, and transmits the set frame number as a downlink transmission start instruction.

[0047] In the examples of Figures 4(d) and (e), the maximum transmission time between the line control device 2 and multiple base station devices 3 is set to a maximum of one frame time (40 ms), and when the control unit 22 of the line control device 2 transmits a downlink transmission start instruction with frame number 1 (when the transmission timing specification frame number is "1"), the transmission timing frame number set for the downlink transmission start instruction is set to "3". As a result, when the plurality of base station devices 3 receive the downlink transmission start instruction, they all start downlink transmission at frame number "3". As a result, regardless of differences in distance from the line control device 2, the transmission timings of the multiple base station devices 3 are synchronized.

[0048] Here, in this wireless communication system, the target of downlink transmission is limited to base station devices 3 within the area of ​​which mobile station devices 4 are located, so the downlink transmission start instruction is also sent only to the base station devices 3 that are the target of the downlink transmission.

[0049] [Downstream transmission timing control: Figure 5] Next, the control of the downlink transmission timing will be described with reference to Fig. 5. Fig. 5 is a sequence diagram showing the control of the downlink transmission timing. As shown in Figure 5, when a command to start transmission is sent from the command desk 1 or the data server 6 (S11), the line control device 2 receives it, assigns a transmission frame timing number to the data from the command desk 1 or the data server 6, and generates a telegram instructing the start of downstream transmission (S12). As described above, the transmission frame timing number is a number that specifies the timing at which each base station device 3 starts downlink transmission.

[0050] Then, the line control device 2 transmits the generated downlink transmission start instruction to the plurality of base station devices 3 that perform downlink transmission. Here, since the transmission start instruction from the data server 6 is a response to the uplink data transmission, the downlink transmission start instruction is transmitted to the stored base station device 3. Upon receiving the downlink transmission start instruction, the base station device 3 starts downlink transmission when the frame number counted within the device itself matches the transmission frame timing number included in the received downlink transmission start instruction.

[0051] [Downstream data transmission relative to upstream data transmission (1): Figure 6] Next, downlink data transmission (1) in this wireless communication system will be described with reference to Fig. 6. Fig. 6 is a sequence diagram showing downlink data transmission (1) (hereinafter referred to as downlink data transmission (1)) in response to uplink data transmission. FIG. 6 shows the operations of the data server 6, the line control device 2, and the base station devices 3-n-1, 3-n, and 3-n+1.

[0052] Here, the base station devices 3 are arranged in a line, and the base station device 3-n is adjacent to the base station device 3-n-1 and the base station device 3-n+1, ​​with their areas partially overlapping. The base station devices 3 may be arranged in a plane, in which case the number of adjacent base station devices 3 will be greater.

[0053] 6, when uplink data transmission is performed from the base station device 3-n (S21), the line control device 2 stores the line used by the base station device 3-n (line used by the base station) (S22). The uplink data transmission is, for example, periodic location information notification from the mobile station device 4. Then, the line control device 2 transmits the received upstream data to the data server 6 (S23).

[0054] When the data server 6 receives the upstream data, it checks the consistency of the data and transmits a downstream data transmission (response) as a response to the upstream data (S24). When the line control device 2 receives the downlink data transmission (response), it reads out the stored line used by the base station, sets it as the destination of the downlink data transmission (response), and transmits the downlink data transmission (response) only to the base station device 3-n that is the destination of the downlink data transmission (response) (S26).

[0055] If a plurality of base station use lines are stored, downlink data transmission (response) is also transmitted to the base station devices 3 corresponding to each use line. At this time, as described above, the line controller 2 transmits the downlink transmission start timing of the base station device 3 in the downlink data transmission (response). In this way, downstream data transmission (1) is carried out.

[0056] As a result, if a mobile station device 4 is present within the area, downlink data can be transmitted in response only to the base station device 3 that has performed uplink data transmission. The base station device 3 in question will transmit downlink data, but other base station devices 3 will not. Therefore, if a new mobile station device 4 enters the area, it can immediately notify the location information, thereby improving the efficiency of data transmission throughout the system. When the next uplink data transmission starts, the line control device 2 resets the stored line used by the base station, and when uplink data transmission from the mobile station device 4 is received, it overwrites and updates it.

[0057] [Occurrence of blind zones: Figure 7] When the base station devices 3 are located far enough apart, data transmission can be performed efficiently using the sequence shown in Fig. 6. However, when the base station devices 3 are located adjacent to each other and their communication areas partially overlap, blind zones occur. The occurrence of a dead zone will be explained using Fig. 7. Fig. 7 is an explanatory diagram showing the occurrence of a dead zone. As shown in Figure 7, when downlink data (response) is transmitted only to base station device 3-n that is stored as a line used by the base station, even if that base station device 3-n starts downlink data transmission, adjacent base station devices 3-n-1 and 3-n+1 do not transmit downlink data and are in a state where uplink data transmission is possible.

[0058] Therefore, in overreach area 71 where the areas of base station device 3-n-1 and base station device 3-n overlap, and overreach area 72 where the areas of base station device 3-n and base station device 3-n+1 overlap, downlink data from both base stations may become congested, resulting in a dead zone.

[0059] [Neighboring base station] Therefore, in this wireless communication system, as another downlink data transmission method (downlink data transmission (2) in response to uplink data transmission, hereinafter referred to as downlink data transmission (2)), downlink data (response) is transmitted not only to the base station device 3 stored as the line used by the base station, but also to adjacent base station devices 3 (adjacent base stations). The adjacent base stations are stored in the line control device 2 in association with each base station device 3, and are base station devices 3 whose communication areas partially overlap with those of the base station device 3 in question.

[0060] When transmitting downlink data, the number of adjacent base stations to which the same downlink data is transmitted (the number of adjacent base stations) is preset depending on the environment in which the system is installed, etc. Downstream data transmission (1) shown in FIGS. 6 and 7 is a case in which downstream data is transmitted only to the base station device 3 corresponding to the line used by the base station, and the number of adjacent base stations is set to "0".

[0061] On the other hand, in downlink data transmission (2), when transmitting downlink data (response), the line control device 2 transmits the same downlink data not only to the base station device 3 stored as a line used by the base station, but also to an adjacent base station stored in correspondence with the base station device 3.

[0062] [Downstream data transmission relative to upstream data transmission (2): Figure 8] Here, a description will be given of downlink data transmission (2) relative to uplink data transmission when the number of adjacent base stations is "2" with reference to Fig. 8. Fig. 8 is a sequence diagram showing downlink data transmission (2) relative to uplink data transmission. In FIG. 8, steps S31 to S34 are the same as steps S21 to S24 shown in FIG. 6, and therefore a description thereof will be omitted.

[0063] When a downstream data transmission (response) is received from the data server 6 in process S34, the line control device 2 reads out the stored base station line used and sets it as the destination of the downstream data transmission (response), and also reads out the adjacent base station stored corresponding to the base station device 3 and sets the line used by the adjacent base station as the destination as well (S35).

[0064] Then, the line control device 2 sends a downstream data transmission (response) to the base station device 3-n (S36), and sends the same downstream data transmission (response) to the adjacent base station device 3-n-1 and base station device 3-n+1 (S37, S38). In this way, downstream data transmission (2) is performed in response to upstream data transmission.

[0065] [Operational status when the number of adjacent base stations is 2: Figure 9] The operation state when the number of adjacent base stations is set to two will be described with reference to Fig. 9. Fig. 9 is an explanatory diagram showing the operation state when the number of adjacent base stations is set to two. In FIG. 9, similar to FIG. 7, base station device 3-n-1, base station device 3-n, and base station device 3-n+1 are arranged in a line.

[0066] Then, as shown in the sequence of Figure 8, if the same downlink data transmission (response) is sent to base station device 3-n as well as base station device 3-n-1 and base station device 3-n+1, ​​all three base stations will perform downlink transmission at the same time.

[0067] As a result, data congestion does not occur in the overreach area 71 and the overreach area 72, and downlink transmission is carried out normally. In other words, downlink transmission is carried out normally anywhere within the area of ​​the base station device 3-n in which the mobile station device 4 that performed uplink data transmission is located, and no blind zones occur.

[0068] In this way, when base station devices 3 are arranged in a line, by setting the number of adjacent base stations to "2", downlink data can be transmitted to both adjacent base station devices 3, preventing the occurrence of blind spots and maintaining the reliability of the service. In addition, overreach areas 73 and 74 are formed with adjacent base station devices 3 at the left end of the area of ​​base station device 3-n-1 and the right end of the area of ​​base station device 3-n+1, ​​and these become dead zones. However, since mobile station device 4 is not present in the areas of base station device 3-n-1 and base station device 3-n+1, ​​the impact is limited.

[0069] The arrangement of the base station devices 3 is not limited to series, but may be parallel, or may be in a planar form such as a honeycomb or random pattern. The control unit 22 of the line control device 2 stores the number of base station devices 3 adjacent to each base station device 3 according to the arrangement of the base station devices 3.

[0070] [Effects of the embodiment] According to this wireless communication system, the system has a plurality of base station devices 3 that perform downlink transmission using the same frequency, and a line control device 2 that controls the base station devices 3. When the line control device 2 receives uplink data from a base station device 2, it stores the line used by that base station device 3 and transmits downlink data in response to the uplink data to the stored line used by the base station device 3. This means that downlink data is not transmitted to base station devices 3 that do not require a response, and uplink data transmission from new mobile station devices 4 is possible, thereby improving the data transmission efficiency of the entire system.

[0071] Furthermore, according to this wireless communication system, when the line control device 2 transmits downlink data in response to uplink data, it transmits the downlink data to the lines used by the base station device 3 in an area adjacent to the area of ​​the base station device 3 in addition to the lines used by the stored base station device 3. This prevents interference between downlink data from both base stations in overlapping areas, creating blind zones, and ensures that downlink data can be received normally throughout the area of ​​the stored base station device 3, thereby ensuring the reliability of communication services. [Industrial Applicability]

[0072] The present invention is suitable for a wireless communication system that can improve data transmission efficiency within the system. [Explanation of symbols]

[0073] REFERENCE SIGNS LIST 1...command console, 2...line control device, 3...base station device, 4...mobile station device, 5...location information collection device, 6...data server, 7...GPS satellite, 21...frame generation unit, 22...control unit, 23...base station interface unit, 24...GPS antenna, 71, 72, 73, 74...overreach area, 211...GPS module, 212...PLL unit, 213...superframe counter, 221...CPU

Claims

1. A wireless communication system having a plurality of base station devices that perform downlink transmission using the same frequency, and a line control device that controls the plurality of base station devices, The line control device stores adjacent base stations corresponding to the plurality of base station devices whose communication areas partially overlap with those of the base station devices, and when it receives uplink data from a base station device, it stores the line used by the base station device, and when it transmits downlink data in response to the uplink data to the line used by the stored base station device, if there is no adjacent base station corresponding to the stored base station device, it transmits the downlink data only to the stored base station device.

2. The wireless communication system according to claim 1, characterized in that when the line control device transmits downlink data in response to the uplink data to the line used by the stored base station device, if there is an adjacent base station corresponding to the stored base station device, the line control device transmits the downlink data to the line used by the adjacent base station in addition to the stored base station device.

3. The wireless communication system according to claim 1 or 2, characterized in that, when transmitting the downlink data, the line control device specifies to each base station device to which the data is to be transmitted that the timing at which each base station device will start transmitting the downlink data is the timing that is the maximum transmission time between the line control device and the plurality of base station devices from the transmission timing of the downlink data.

4. 3. The wireless communication system according to claim 1, wherein the areas of the plurality of base station devices are arranged in a line or a plane.

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