JP4828454B2 - Wide area wireless communication system and timing adjustment method thereof - Google Patents

Description

  The present invention relates to a wide area wireless communication system and a timing adjustment method thereof capable of simultaneous multi-station transmission in a wide area wireless communication system in which a plurality of base stations are connected to a plurality of head office devices in a tree shape.

  FIG. 4 is a block diagram showing a configuration of a general wireless communication system. FIG. 4 shows a configuration in which a plurality of base stations 4 and 5 are connected to one central head office apparatus 1 in a tree shape by dedicated digital link lines. The central head office device 1 and the base stations 4 and 5 are provided with GPS receiving means for receiving radio waves from the GPS satellite device 11. As a communication method, a TDMA (Time Division Multiple Access) method for transmitting a digital signal in units of frames with a constant period is used.

  In order to carry out multi-station simultaneous transmission in this system, each base station 4, 5 determines the line delay time between the central head office 1 and each base station 4, 5 in accordance with an instruction from the central head office 1. The measurement is made and the result is notified to the central head office apparatus 1. The central headquarters apparatus 1 obtains the maximum delay time from the line delay times notified from the base stations 4 and 5, notifies the base stations 4 and 5 of the maximum delay time, , 5 transmits the digital signal at a delay time obtained by subtracting the line delay time of the own station from the maximum delay time, so that the timings of the digital signals transmitted from the respective base stations are aligned, so that multiple stations can transmit simultaneously. Is possible.

JP 2002-27534 A

  In the prior art, multi-station simultaneous transmission / reception is possible only in a configuration in which a plurality of base stations are connected to one head office device, and multi-station simultaneous transmission is performed between base stations connected to different head office devices. However, it was necessary to transmit at a different frequency. For this reason, the frequency of the wireless line could not be effectively used.

  The present invention has been made to solve the above-described problems. The central headquarters apparatus and a plurality of general headquarter apparatuses are connected by a dedicated digital line, and a plurality of base stations are connected to each headquarter apparatus in a tree shape. Even in a wide area wireless communication system that is connected by a dedicated digital line and transmits a digital signal in a frame unit of a fixed period, it is possible to achieve effective use of frequencies by enabling simultaneous transmission of multiple stations. To do.

The subject of the present invention is that a central headquarters apparatus and a plurality of general headquarters apparatuses are connected to each other by dedicated digital lines, and a plurality of base stations are connected to each headquarter apparatus by a dedicated digital line in a tree shape, and in units of frames of a fixed period in wide-area wireless communication system for transmitting digital signals, said central headquarters unit and the general division device includes a GPS receiving means for receiving a GPS, a downstream frame transmission timing calculating means, and a maximum delay time calculating means, said central The headquarter device is configured to obtain a first time difference between a frame immediately after reception of the GPS first reference signal received by the GPS receiving means and the first reference signal, information on the frame number of the frame, and the frame. A delay receiving time measurement command, a plurality of general headquarters devices and a GPS receiving means connected thereto Transmitted to the ground station, the general division device is notified from each of the second group Chikyoku equipped with GPS receiving means connected to itself, the reference signal second given by the period of the next subsequent collect first delay time indicating a delay from the time the reference signal reception, along with determining the maximum delay time by Ri first to the maximum delay time calculating means from the collected first delay time, based on the delay command time measurement from the central headquarters unit, by the downlink frame transmission timing calculating unit of the general headquarters unit, measures a second time difference between said at the time of reception of the second reference signal frames Then, by subtracting the first time difference from the second time difference, a first line delay time between the general headquarter device and the central headquarter device is obtained, and the first delay time calculated as the line delay time is calculated . the maximum delay time of 1 and A second delay time obtained by calculation and notification to the central headquarters unit, the central headquarters unit is notified based on a command delay time measurement from said central headquarters unit from the second base station the The first delay time and the second delay time notified from each general headquarter device are collected, and the second delay time is calculated by the maximum delay time calculation means from the collected first and second delay times. A delay time is obtained, and the second maximum delay time is notified to the first base station and each general headquarters device, and the first base station is based on the delay time measurement command from the central headquarter device. Then, a downlink frame transmission timing calculating means included in the first base station measures a third time difference between the reception of the second reference signal and the frame, and the first time difference is used to calculate the first time difference. By subtracting the time difference, The second maximum delay notified from the central head office device based on a delay time adjustment command from the central head office device while calculating a second line delay time between itself and the central head office device There first row radio transmission delays the time obtained by subtracting the second line delay time from the time, the common division device, from said second maximum delay time notified from the central headquarters unit, the The second base station is notified of a second time obtained by reducing the line delay time between the general headquarters device and the central headquarters device, and the second base station receives a delay from the central headquarter device. on the basis of a command time adjustment, the between from said second base station in the connected the general headquarters unit notified the second time from the said second base station and the general headquarters device the remaining time delayed obtained by subtracting the first delay time Performs wireless transmission Te is, and performing a multi station simultaneous transmission.

  Hereinafter, various embodiments of the subject of the present invention will be described in detail along with the effects and advantages thereof with reference to the accompanying drawings.

  According to the subject matter of the first invention, in a wide area radio communication system in which different headquarter devices are connected through a dedicated digital line, the delay time between the headquarter devices is taken into account, so that the signal transmitted from each base station It is possible to obtain a system that adjusts the timing and realizes simultaneous multi-station transmission.

  According to the subject matter of the second invention, even when the delay time varies between the head office device and the base station or between the head office devices, the delay time is automatically measured and the transmission / reception timing is automatically readjusted. And maintainability can be further improved.

(Embodiment 1)
The main point of this embodiment is that the central headquarters device and a plurality of general headquarters devices are connected to each other by a dedicated digital line, and a plurality of base stations are connected to each headquarter device by a dedicated digital line in a tree shape. In a wide area radio communication system that transmits digital signals in units, the radio transmission timing from each base station to the mobile station in consideration of the delay time between the headquarter devices and the delay time between each headquarter device and its own base station, The point is to adjust the delay time until wireless transmission in each base station so that it is aligned with the wireless transmission timing of the farthest base station as viewed from the central head office apparatus.

  In order to realize such a system, in the present system, each general headquarter apparatus includes GPS receiving means for receiving GPS, downlink frame transmission timing calculating means, and maximum delay time calculating means. The downlink frame transmission timing calculation means measures or calculates a time difference between the reception time of the reference signal having a 1-second cycle obtained from the GPS reception means and the arrival time of the downlink frame transmitted from the central headquarter apparatus.

  Each base station includes GPS receiving means for receiving GPS, wireless transmission timing calculating means, wireless transmission delay means, and wireless transmission means. The wireless transmission timing calculation means measures or calculates the time difference between the reception time of the reference signal having a 1-second period obtained from the GPS reception means and the arrival time of the downlink frame transmitted from the headquarter apparatus connected to the base station. Then, the head office apparatus is notified of the time difference data as a delay time.

  Each general headquarters device calculates the maximum value as the maximum delay time from the delay times notified from each base station connected to the general headquarters device, and the already calculated center The above-mentioned line delay time with the head office device is added, and the obtained added value is notified to the central head office device as a delay time.

  The central head office apparatus obtains the maximum value from the delay times collected from each general head office apparatus and its own base station as the maximum delay time in this system, and the data of this maximum delay time is obtained from the own base station and each general head office apparatus. To notify.

  Each general headquarters device notifies each base station as a delay time of a value obtained by subtracting the measured line delay time to the general headquarters device from the maximum delay time in the communication system notified from the central headquarters device, Each base station obtains the remaining time obtained by subtracting the delay time between the base station and the corresponding general head office device from the delay time notified from the corresponding general head office device, in the delay in the radio transmission delay means. By setting the time, the wireless transmission means of each base station delays the remaining time after the delay time has elapsed, that is, the delay time from the maximum delay time in the communication system to the own station. In this case, multi-station simultaneous transmission is executed by wireless transmission. Hereinafter, the contents of Embodiment 1 of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a wide area radio communication system according to the first embodiment. As shown in FIG. 1, a plurality of base stations 4 and 5 are connected to a central headquarter apparatus 1 that manages overall transmission / reception timings by dedicated digital lines. In addition, the general headquarters devices 2 and 3 are connected to the lower level of the central headquarters device 1 by a dedicated digital line, and a plurality of base stations 6 to 9 are connected to the respective general headquarters devices 2 and 3. Wireless communication is performed between the mobile station 9 and the mobile station 10.

  Here, F1 is assigned to the downlink radio frequency of the mobile station 10, F2 is assigned to the uplink radio frequency, and a radio signal of frequency F2 is transmitted to the base station in synchronization with the radio signal of frequency F1 from the base station. . In this system, the above-described TDMA system is used in which reception and transmission are performed in units of frames.

  For example, the timing between a radio signal having a downlink frequency F1 (5-10) from the base station 5 to the mobile station 10 and a radio signal having a downlink frequency F1 (9-10) from the base station 9 to the mobile station 10 is constant. If the time is shifted more than the time, the radio signal of the downlink frequency F1 (5-10) and the radio signal of the downlink frequency F1 (9-10) interfere with each other, and the mobile station 10 cannot receive the transmitted radio signal normally. There is a possibility. For this reason, it is necessary to set the transmission timing of the radio signal of the downlink frequency F1 (5-10) and the transmission timing of the radio signal of the downlink frequency F1 (9-10) to be the same. For this purpose, the transmission path delay time until the downlink frame arrives at the base station located farthest from the central headquarters apparatus 1 in the wide area wireless communication system is measured. It should be realized that each other base station transmits a radio signal in accordance with the transmission timing from a distant base station, and such a transmission form is called “multi-station simultaneous transmission”.

  Here, FIG. 2 is a timing chart schematically showing a timing adjustment method for simultaneous transmission of multiple stations in a wide area wireless communication system. FIG. 3 is a block diagram showing the configuration of the central head office apparatus 1. Although not shown, each of the general headquarter apparatuses 2 and 3 connected to the central headquarter apparatus 1 is also “GPS receiving means” and “downlink frame transmission timing calculating means” as in the central headquarter apparatus 1. And “maximum delay time calculating means”.

  Next, a timing adjustment method for simultaneous transmission of multiple stations in the wide area radio communication system in the present embodiment will be described with reference to FIGS.

  When the length of one frame is set to 1 / N seconds in the line between the headquarters and the base station (when one second is divided into N frames), the user passes through the management device 12 in the central headquarters 1 When the central headquarters apparatus 1 instructs the measurement of the delay time, the frame number immediately after the reception of the reference signal of the 1 second period obtained from the GPS receiving means 13 by the downstream frame transmission timing calculating means 14 (in the example of FIG. 2). The frame number is N) and its time difference Δt is measured.

Next, the central headquarters apparatus 1, after the next frame, (frame number in the example of FIG. 2 N) delay command and the frame number of the time measured by carrying the information of the time difference Delta] t, the base station 4 and 5 In addition, the general headquarters devices 2 and 3 are notified. Each of the general headquarters devices 2 and 3 and the own base stations 4 and 5 receive the frame number notified from the central headquarters device 1 (the frame number is N in the example of FIG. 2) and one obtained from the GPS receiving means. By measuring the time difference from the reception of the reference signal of the second period and subtracting the data of the time difference Δt from the measurement result, the line delay time between the central headquarters device 1 (here, the central headquarters device 1 and each general headquarters) (In the example of FIG. 2, the line delay time between the central head office device 1 and its own base stations 4 and 5 is Δt1, and the central head office device 1 is defined as ΔT.) And the line delay time between the general headquarters apparatus connected to the farthest base station is ΔTH).

  Further, each of the general headquarter apparatuses 2 and 3 receives the instruction of the delay time measurement from the central headquarter apparatus 1 and, similarly to the central headquarter apparatus 1, the general headquarter apparatuses 1 and 3 perform GPS by the downlink frame transmission timing calculation means (not shown). The frame number immediately after reception of the reference signal with a period of 1 second obtained from the receiving means (not shown) (the frame number is (N-2) in the example of FIG. 2) and its time difference Δt ′ are measured, and the next frame Thereafter (after the frame (N−1) in the example of FIG. 2), the delay time measurement command, its frame number (the frame number is (N−2) in the example of FIG. 2), and the information of the time difference Δt ′. Put it on and notify your base stations 6-9.

  The own base stations 6 to 9 of the general headquarter apparatuses 2 and 3 are based on the information of the frame number notified from the corresponding general headquarter apparatus (the frame number is (N-2) in the example of FIG. 2) and the time difference Δt ′. First, the GPS receiving means (not shown) and the wireless device timing calculating means (not shown) first receive the reference time of the reference signal having a one-second cycle obtained from the GPS receiving means (not shown), and the reference Measure the time difference between the notified frame number immediately after reception of the signal (in the example of FIG. 2, the frame number is (N-2)) and the reception time of the downlink frame to the base station, and then the measured time difference A delay time obtained by subtracting the data of the time difference Δt ′ from the data (here, the delay time is defined as ΔTB, and in the example of FIG. 2 in particular, the base station located farthest from the central head office 1) Delay measured and calculated by The time is indicated as ΔTBmax.) And the calculated delay time is notified to the corresponding general head office apparatus.

  Thereafter, each of the general headquarters 2 and 3 collects the data of the delay time ΔTB notified from the base stations 6 to 9 by the maximum delay time calculation means (not shown), and these ΔTB The maximum value ΔTBM is calculated from the data group, and then the delay time (ΔTBM + ΔT) obtained by adding the delay time ΔT between the central headquarter apparatus 1 and the general headquarter apparatuses 2 and 3 to the maximum value ΔTBM. ) (Particularly in the example of FIG. 2, ΔTBmax + ΔTH) is sent to the central head office apparatus 1.

  Thereafter, the central headquarters apparatus 1 uses the maximum delay time calculation means 15 from the data group of the delay times notified from the base stations 4 and 5 and the general headquarter apparatuses 2 and 3 in the wide area wireless communication system. 2 (the maximum delay time here is ΔTBmax + ΔTH according to an example of FIG. 2), and the data of the maximum delay time (ΔTBmax + ΔTH) is obtained for each general headquarter device 2, 3 and each own base station 4, 5 and instruct the delay time adjustment.

  The base stations 4 and 5 of the central head office apparatus 1 delay by the time (ΔTBmax + ΔTH−Δt1) obtained by subtracting the delay time Δt1 (see FIG. 2) of the local station from the maximum delay time (ΔTBmax + ΔTH) notified from the central head office apparatus 1. Wireless transmission is performed at the specified timing.

  Each of the general head office apparatuses 2 and 3 determines the delay time ΔT from the maximum delay time (ΔTBmax + ΔTH) notified from the central head office apparatus 1 to the measured own station (the example of FIG. In the general headquarters apparatus connected to the base station at the farthest end, the measured delay time to the own station is notified to the own base stations 6 to 9 as a delay time. In response to the notification, each of the base stations 6 to 9 determines the delay time ΔTB of its own station from the delay time notified from the corresponding general headquarter apparatuses 2 and 3 (the farthest end with respect to the central headquarter apparatus 1 shown in FIG. 2). In the case of this base station, the own station delay time is ΔTBmax.) Radio transmission is performed at the timing delayed by the remaining time obtained by subtracting (the central station apparatus 1 shown in FIG. In the case of a far-end base station, the delay time remaining after reduction is 0 seconds (ie, no delay). By adjusting the timing of wireless transmission of each of the base stations 4 to 9, a certain frame (for example, frame N) is wirelessly transmitted from each of the base stations 4 to 9 to the mobile station 10 in the wide area wireless communication system of FIG. Are aligned with the timing at which a certain frame (for example, frame N) is wirelessly transmitted from the farthest end base station to the central head office 1 to the mobile station 10, and as a result, all the base stations Simultaneous transmission from 4 to 9 is possible.

(Embodiment 2)
In the present embodiment, the central headquarters apparatus 1 further includes a timer function means (not shown). When the set time is reached, the general headquarters apparatuses 2 and 3 and the own base stations 4 and 5 are automatically The delay time measurement as described in the first embodiment is instructed.

  By adding such a timer function, even when there is a variation in the delay time, when the time set in the timer function means is reached, the system performs the delay time adjustment as described in the first embodiment, It is possible to automatically adjust the transmission timing of each base station to maintain simultaneous transmission of multiple stations.

(Appendix)
While the embodiments of the present invention have been disclosed and described in detail above, the above description exemplifies aspects to which the present invention can be applied, and the present invention is not limited thereto. In other words, various modifications and variations to the described aspects can be considered without departing from the scope of the present invention.

It is a block diagram of the wide area radio | wireless communications system which concerns on Embodiment 1 of this invention. It is a timing chart which shows the timing adjustment method of the multi-station simultaneous transmission of the wide area radio | wireless communications system which concerns on Embodiment 1 of this invention. It is a block diagram of the central headquarters apparatus of the wide area radio | wireless communications system which concerns on Embodiment 1 of this invention. It is a block diagram of the conventional radio | wireless communications system.

Explanation of symbols

  1 Central headquarters device, 2, 3 General headquarters device, 4, 5, 6, 7, 8, 9 Base station, 10 Mobile station, 11 GPS satellite device, 12 Management device, 13 GPS receiving means, 14 Downlink frame transmission timing calculation Means, 15 Maximum delay time calculating means.

Claims (3)

Central headquarters and multiple general headquarters are connected to each other via dedicated digital lines, and multiple base stations are connected to each headquarters via a dedicated digital line in the form of a tree. In a wireless communication system,
The central headquarter device and each general headquarter device include GPS receiving means for receiving GPS, downlink frame transmission timing calculating means, and maximum delay time calculating means,
The central headquarters device includes a first time difference between a frame immediately after reception of the GPS first reference signal received by the GPS receiving means and the first reference signal, and information on the frame number of the frame, A delay time measurement command for the frame is transmitted to the first base station including the plurality of general headquarters devices and GPS receiving means connected to the frame;
Each general headquarters device is notified from each of the second group Chikyoku equipped with GPS receiving means connected to itself, from the second reference signal upon receipt given by the following subsequent cycle of the reference signal collect first delay time indicating a delay, along with from the collected first delay time determining a first maximum delay time Ri by the maximum delay time calculating means, from the central headquarters unit on the basis of a command of the delay time measurement, by the downlink frame transmission timing calculating unit of the general headquarters device, a second time difference between said at the time of reception of the second reference signal frame is measured, the second By subtracting the first time difference from the time difference, a first line delay time between the general headquarter device and the central headquarter device is obtained, and the line delay time and the calculated first maximum delay time obtained by adding the The second delay time to notify the central headquarters unit,
The central headquarters device receives the first delay time notified from the second base station based on a delay time measurement command from the central headquarter device and the second delay notified from each general headquarter device. Time is collected, a second maximum delay time is obtained from the collected first and second delay times by the maximum delay time calculating means , and the first base station and each general headquarter apparatus receive the second maximum delay time . 2 of the maximum delay time,
The first base station receives the second reference signal by the downlink frame transmission timing calculation means included in the first base station based on the delay time measurement command from the central headquarters. By measuring a third time difference with the frame and subtracting the first time difference from the third time difference, a second line delay time between itself and the central head office device is calculated, and based on a command delay time adjustment from the central headquarters unit, said from the central headquarters unit maximum delay time notified the second from delaying the first time obtained by subtracting the second line delay time wireless transmission the stomach line,
Each general headquarters unit, from the central headquarters unit notified the second maximum delay time, the second time obtained by subtracting the line delay time between said with the general headquarters device central headquarters unit, wherein Inform the second base station,
The second base station, from said on the basis of an instruction of the delay time adjustment from the central headquarters unit, the notified second time from said general headquarters device connected to the second base station, the Multi-station simultaneous transmission is performed by delaying the remaining time obtained by reducing the first delay time between the second base station and the general headquarter device, and performing wireless transmission.
Wide area wireless communication system. A wide area wireless communication system according to claim 1,
The central headquarters device has a timer function that can automatically instruct each general headquarters device and each base station to measure and adjust the delay time at a set time. ,
Wide area wireless communication system. A timing adjustment method using the wide area wireless communication system according to claim 1,
The central headquarters apparatus uses the second maximum delay time obtained by the maximum delay time calculation means as the maximum delay time to the base station at the farthest end when viewed from the central headquarters apparatus ,
The second base station sets the maximum delay time to the farthest base station to 0 by delaying the remaining time obtained by subtracting the first delay time from the second time. A timing adjustment method for a wide area wireless communication system, characterized in that multi-station simultaneous transmission is performed.

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