JP4700517B2 - Wireless communication device - Google Patents

Description

  The present invention relates to a wireless communication device that constitutes a signal transmission system, and particularly relates to a wireless communication device having a function of transferring a received signal to another wireless communication device different from the transmission source of the received signal. It is.

  In a signal transmission system, a wireless bridge that is used to extend the reach of a radio wave (signal) that changes depending on transmission power without increasing the transmission power is described in Patent Document 1 below.

  According to Patent Document 1 below, a wireless station that becomes a wireless bridge scans other wireless stations located around its own station at the time of initial setting, for example, and transmits a signal whose reception level is equal to or higher than a threshold value Only other wireless stations to be selected are selected as connectable wireless stations, and thereafter, received signals from the selected wireless stations are transferred. By using such a wireless bridge, a wireless station that is a signal transmission source can transmit a signal to a wireless station that does not directly receive radio waves, and the signal reachable distance without increasing transmission power. Can be stretched.

JP 2003-188811 A

  However, in the above-described conventional wireless bridge, all wireless bridges that have received a signal of a predetermined reception level or higher from a specific wireless bridge transfer the received signal. Therefore, a plurality of wireless bridges are provided in the vicinity of the wireless bridge that is the signal transmission source. When there is a bridge, there is a problem that traffic increases more than necessary and transmission efficiency deteriorates.

  The present invention has been made in view of the above, and is a wireless communication that prevents traffic from increasing more than necessary due to transfer processing of a received signal in a signal transmission system, and prevents transmission efficiency from deteriorating. The object is to obtain a device.

  In order to solve the above-described problems and achieve the object, the present invention is a wireless communication device that constitutes a signal transmission system, and the specific wireless communication device transmits a reception signal from the specific wireless communication device. Receiving signal transfer means for transferring to other wireless communication devices located outside the signal arrival area, and signal transfer control means for controlling the received signal transfer means based on the received signal level. And

  According to the present invention, when the signal reception level is very high (the distance from the signal transmission source device is short), the wireless communication device refrains from transferring the reception signal and the signal reception level is not so high (signal Since the received signal is transferred when the distance to the transmission source device is long), the number of times the same signal is transferred within the system is prevented from increasing unnecessarily, and traffic is prevented from increasing efficiently. There is an effect that the reach distance can be extended.

  Embodiments of a wireless communication apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a signal transmission system including a wireless communication device (hereinafter referred to as a wireless station) according to the present invention. Further, FIG. The state of operation is shown. The signal transmission system includes a radio base station (hereinafter referred to as a base station) 10 and radio stations 11 to 15, and the base station 10 transmits a broadcast signal.

  Here, in the example shown in FIG. 1, the radio stations 11 to 13 are located in a place where the signal transmitted by the base station 10 can be directly received (within the arrival area of the transmission signal), and the radio stations 14 and 15 are Suppose that it is located in a place where the direct transmission of the signal transmitted by the base station 10 is impossible (outside the transmission signal reachable area). Therefore, the radio stations 14 and 15 receive the transmission signal from the base station 10 via other radio stations, that is, the other radio stations that directly received the transmission signal from the base station 10 transfer it, The radio stations 14 and 15 receive the transmission signal from the base station 10 transferred by the other radio stations. Note that the radio stations 14 and 15 that have received the transferred signal further transfer the received signal transferred from the other radio station when a predetermined condition is satisfied.

  Next, the operation of each wireless station will be described with reference to FIGS. FIG. 2 is a diagram illustrating a configuration example of a wireless communication apparatus (wireless station) according to the present invention. The wireless station includes a reception unit 21, a reception level measurement unit 22, a reception determination unit 23, and a transfer control unit. 24 and a transmission unit 25.

  The reception unit 21 of the radio station receives the broadcast signal transmitted from the base station 10 and outputs the received signal to the reception level measurement unit 22. The reception level measurement unit 22 measures the level of the reception signal received from the reception unit 21 and outputs the measurement result and the received reception signal to the reception determination unit 23. The reception determination unit 23 performs error determination of the reception signal received from the reception level measurement unit 22. Further, the reception determination unit 23 outputs the level measurement result of the reception signal (hereinafter simply referred to as “reception level”) to the transfer control unit 24.

  The transfer control unit 24, which is a signal transfer control means, compares the received reception level with a predetermined threshold value, and determines whether or not to execute signal transfer processing based on the comparison result. Then, the transmission unit 25 which is a reception signal transfer unit executes a reception signal transfer process according to the determination content of the transfer control unit 24.

  Specifically, when the received reception level is less than a predetermined threshold, the transfer control unit 24 controls the transmission unit 25 to execute a transfer process of the received signal. On the other hand, when the reception level is equal to or higher than the threshold value, the transfer control unit 24 controls the transmission unit 25 so as not to execute the reception signal transfer process. This is because when a reception level is very high in a certain radio station, the distance to the signal transmission source device (base station or radio station) is predicted to be short, and even if this radio station performs signal transfer, the signal arrives. This is to prevent the adverse effect that the distance cannot be expected to increase greatly (the effect cannot be expected) and conversely the traffic increases due to an increase in the number of transfers. In addition, a radio station with a lower reception level than a radio station with a very high reception level (that is, a radio station with a longer distance from the signal transmission source device) performs signal transfer, thereby efficiently transmitting signals with a smaller number of transfers. This is because the reach distance can be extended.

  Here, in the example shown in FIG. 1, the reception level of the signal from the base station 10 in the wireless station 11 is equal to or higher than the threshold value, and the reception level of the signal from the base station 10 in the wireless stations 12 and 13 is the threshold. If it is less than the value, the wireless station 11 does not transfer the received signal. On the other hand, the radio stations 12 and 13 transfer received signals. Then, the radio stations 14 and 15 to which the radio wave from the base station 10 does not reach directly receive the broadcast signal from the base station by receiving the signal transferred by the radio station 12 or 13.

  In the above description, the transfer control unit 24 of each radio station determines whether to execute signal transfer processing based on the signal reception level. For example, the signal transmission source base station or radio It may be determined based on the physical distance to the station. Specifically, the transfer control unit 24 controls the transmission unit 25 to execute the received signal transfer process only when the distance from the signal transmission source base station or radio station is long. In addition, the acquisition of the physical distance is, for example, by detecting the distance between the surrounding base station and the radio station by a radar or the like, from the marker or base station installed on the road, the own station and the surrounding base station and the radio station. Get notified of your location.

  In addition, the wireless station 14 shown in FIG. 1 receives two identical signals transferred by the wireless stations 12 and 13, but the transfer control unit 14 of the wireless station 14 performs the above-described operation, thereby causing traffic. Is prevented from increasing more than necessary. For example, when the reception level of the signal from the radio station 12 is equal to or higher than the threshold and the reception level of the signal from the radio station 13 is less than the threshold, the radio station 14 does not transfer the signal from the radio station 13. Since only the signal from the radio station 12 is transferred, it is possible to prevent an increase in traffic.

  Here, when the transfer control unit 24 of each wireless station determines whether to execute the signal transfer process based only on the comparison result between the reception level and the threshold value as described above, the transfer process is permanently performed. And traffic may increase. For this reason, in addition to the control based on the comparison result, a separate transfer end determination control is required. For example, when the base station transmits a broadcast signal including transfer count information (initial value = 0) and the radio station performs transfer of the received signal, the transfer count information is determined as the transfer end determination control. It can be considered that when the wireless station receives a signal whose transfer count information reaches a predetermined value, the wireless station does not execute the transfer process of the signal. It is also conceivable that the base station gives a lifetime by adding a time stamp to the broadcast signal, that is, the radio station does not execute a signal transfer process after a predetermined time has elapsed since being transmitted to the base station. Furthermore, it is conceivable that the wireless station restricts signal transfer according to the distance from the base station that transmitted the broadcast signal before being transferred.

  Thus, in the present embodiment, a radio station with a very high signal reception level (a radio station with a short distance from the signal transmission source device) refrains from transferring the reception signal, and the signal reception level is not so high. A wireless station that is not high (a wireless station with a certain distance from the signal transmission source device) transfers the received signal. As a result, it is possible to prevent the number of transfers of the same signal from increasing unnecessarily in the system, and to efficiently extend the signal reach while preventing an increase in traffic. Further, since it is determined whether or not to transfer the received signal every time a signal is received, the signal transfer operation can be executed flexibly in response to a change in the positional relationship accompanying the movement of the radio station.

Embodiment 2. FIG.
Next, the second embodiment will be described. FIG. 3 is a diagram showing a configuration example of the second embodiment of the signal transmission system including the radio station according to the present invention, and further shows the operation of each device constituting the signal transmission system.

  This signal transmission system includes a base station 10 and radio stations 11, 14, and 15, that is, a configuration in which the radio stations 12 and 13 are excluded from the configuration of the signal transmission system of the first embodiment described above. The configuration of the radio station is the same as that of the radio station in the first embodiment. Also, the physical relationship (positional relationship) between the devices (base station and radio station) is the same as the physical relationship between the devices to which the same reference numerals are assigned in the signal transmission system of the first embodiment. . Therefore, in the signal transmission system according to the present embodiment, only the radio station 11 can directly receive the broadcast signal from the base station 10, and the radio stations 14 and 15 cannot directly receive the broadcast signal from the base station 10. .

  As described above, in the signal transmission system of the present embodiment, there is no terminal (corresponding to radio stations 2 and 3 in the first embodiment) whose signal reception level is lower than the threshold value. Therefore, when each wireless station performs only the same operation as that of the wireless station of the first embodiment, the wireless station 11 having a high signal reception level does not transfer the received signal. As a result, the transfer of the received signal is interrupted, and the radio stations 14 and 15 to which the signal from the base station 10 does not reach directly cannot receive the signal from the base station. Hereinafter, an operation performed by the radio station in order to prevent such inconvenience will be described with reference to FIGS.

  In FIG. 3, since the radio station 11 that directly receives the broadcast signal from the base station 10 has a signal reception level equal to or higher than a preset threshold value, as described in the first embodiment, transfer of the received signal is performed. Do not execute processing. At this time, the wireless station 11 measures the reception level of signals transferred by other wireless stations in the reception level measuring unit 22 and scans (monitors) the status of transfer processing performed by the peripheral wireless stations. If the transfer signal from the surrounding radio station cannot be detected even after scanning for a certain time, the transfer control unit 24 of the radio station 11 determines whether to execute the signal transfer process once determined (in this case, the reception Cancel the signal transfer process) and control the transmitter 25 to execute the received signal transfer process.

  As described above, since the reception level of the signal is equal to or higher than the threshold value, the wireless station 11 that has decided not to execute the transfer processing of the received signal once performs the above-described operation, and thus the wireless station 14 that does not reach the signal directly. And 15 can also receive the broadcast signal from the base station.

  In the description of the present embodiment, a radio station having a signal reception level equal to or higher than a threshold value monitors the status of transfer processing performed by the peripheral radio station by detecting a transfer signal. However, the present invention is not limited to this, and monitoring may be performed by detecting the physical presence / absence of peripheral wireless stations. For example, the distance to the surrounding radio station is detected by a radar or the like, or the location of the surrounding radio station is notified from a marker installed on the road or a radio base station.

  As described above, in this embodiment, since the reception level of the signal is equal to or higher than the threshold value, the wireless station that has decided not to execute the transfer processing of the received signal once monitored the status of the surrounding wireless stations. As a result, when it is determined that there is no other wireless station to which the received signal is transferred, the received signal transfer process is executed. Thereby, it is possible to prevent the transfer of the reception signal from being interrupted.

Embodiment 3 FIG.
Next, Embodiment 3 will be described. FIG. 4 is a diagram showing a configuration example of a third embodiment of a signal transmission system including a radio station according to the present invention, and further shows the operation of each device constituting the signal transmission system.

  The configuration of the signal transmission system and the configuration of the radio station are the same as those of the signal transmission system and the radio station of the first embodiment described above, and only the operation of the radio station is different. The physical relationship (positional relationship) between the devices (base station and radio station) is the same as the physical relationship between the devices to which the same reference numerals are assigned in the signal transmission system of the first embodiment. Therefore, the radio stations 11 to 13 can directly receive the broadcast signal transmitted from the base station, and the radio stations 14 and 15 cannot directly receive the broadcast signal transmitted from the base station.

  The radio station of this embodiment uses two threshold values (Th # 1, Th # 2, where Th # 1> Th # 2), and compares these threshold values with the signal reception level. The point of determining whether or not to perform the received signal transfer operation based on the result is different from the operation of the radio station of the first embodiment. Th # 1 corresponds to the threshold used in the first and second embodiments. Hereinafter, the operation of the radio station according to the present embodiment will be described with reference to FIGS.

  Here, in the example shown in FIG. 4, the reception level of the signal from the base station 10 in the wireless station 11 is Th # 1 or higher, and the reception level of the signal from the base station 10 in the wireless station 12 is Th # 2 or higher. And it is less than Th # 1, and it is assumed that the reception level of the signal from the base station 10 in the radio station 13 is less than Th # 2. In this case, the radio station 13 whose signal reception level is less than Th # 2 determines that there is a high possibility that an error has occurred in the received signal, and does not execute the received signal transfer process. On the other hand, the other radio stations (radio stations 11 and 12) having a signal reception level equal to or higher than Th # 2 are the same as the radio stations of the first embodiment based on the comparison result between Th # 1 and the signal reception level. Perform the operation.

  In FIG. 4, the transfer control unit 24 of the radio stations 11 to 13 that directly receives the broadcast signal from the base station 10 receives the signal based on the reception level of the signal measured by the reception level measurement unit 22 of each radio station. A determination is made as to whether to perform signal transfer processing. Then, the radio station 11 having a reception level equal to or higher than Th # 1 does not execute the reception signal transfer process. Further, the radio station 12 having a reception level equal to or higher than Th # 2 and lower than Th # 1 executes a transfer process of the received signal. In addition, the wireless station 13 whose reception level is less than Th # 2 does not execute the reception signal transfer process. Then, the radio stations 14 and 15 to which the radio wave from the base station 10 does not directly receive the broadcast signal from the base station by receiving the signal transferred by the radio station 12.

  Note that the radio station may perform the operation described in the second embodiment. That is, since the reception level of the signal is equal to or higher than Th # 1, a wireless station (corresponding to the wireless station 11 of the present embodiment) that has determined that the transfer processing of the received signal is not executed once indicates the status of surrounding wireless stations. As a result of monitoring, when it is determined that there is no other wireless station (corresponding to the wireless station 12 of the present embodiment) that transfers the received signal, a transfer process of the received signal is executed.

  As described above, in this embodiment, the radio station does not execute the transfer process of the received signal when the signal reception level is very high, as in the radio station of the first embodiment described above. The received signal transfer process is not executed even when the signal reception level is below a certain level. As a result, it is possible to prevent a received signal that is highly likely to have an error from being transferred, and to extend the reach of the signal more efficiently than in the case of performing the operation of the first embodiment. be able to.

  As described above, the wireless communication device according to the present invention is useful for a signal transmission system, and in particular, for a wireless communication device that extends the reach of a signal by transferring a received signal to another wireless communication device. Is suitable.

It is a figure which shows the structural example of Embodiment 1 of the signal transmission system containing the radio | wireless communication apparatus concerning this invention. It is a figure which shows the structural example of the radio | wireless communication apparatus concerning this invention. It is a figure which shows the structural example of Embodiment 2 of the signal transmission system containing the radio | wireless communication apparatus concerning this invention. It is a figure which shows the structural example of Embodiment 3 of the signal transmission system containing the radio | wireless communication apparatus concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Wireless base station 11, 12, 13, 14, 15 Wireless communication apparatus 21 Reception part 22 Reception level measurement part 23 Reception determination part 24 Transfer control part 25 Transmission part

Claims (2)

A wireless communication device constituting a signal transmission system,
A reception signal transfer means for transferring a reception signal from a specific wireless communication device to another wireless communication device located outside the arrival area of the signal transmitted by the specific wireless communication device;
Signal transfer control means for controlling the received signal transfer means based on a received signal level;
Equipped with a,
The signal transfer control means prevents the received signal transfer means from transferring the received signal to another wireless communication apparatus when the received signal level is equal to or higher than a traffic determination threshold value for preventing an increase in traffic. In addition, even if the received signal transfer means controls not to transfer the received signal to another wireless communication device, the other wireless communication device thereafter has the same content as the received signal. when the predetermined time has elapsed without transferring the signal, the wireless communication device characterized that you control as the reception signal transfer means for transferring the received signal to the other wireless communication device . The signal transfer control means is further configured such that when the received signal level is less than an error determination threshold value for determining whether or not an error has occurred in the received signal, the received signal transfer means transfers the received signal to another signal. The wireless communication apparatus according to claim 1 , wherein the wireless communication apparatus is controlled not to transfer the wireless communication apparatus.

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