JP2011147065A - Radio communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid multipath fading as a method of sequentially changing over reception antennas and to reduce switching of the reception antennas as a whole. <P>SOLUTION: After start-up, antennas A and B are alternately changed over and an antenna resulting from the change-over is defined as a reception antenna. For each of registered transmission nodes, a reception antenna having succeeded in reception of data from the transmission node is stored as an optimal reception antenna. When data from all the registered transmission nodes are successfully received, based on stored optimal reception antennas of transmission devices, a base antenna is determined by majority. After the base antenna is determined, change-over control of the reception antenna is then intercepted and the determined base antenna is fixed as a reception antenna. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wireless communication device suitable for use in a wireless communication system having a mesh network structure.

  In recent years, systems that perform environmental measurement, monitoring, control, and the like using wireless communication are increasing. In a wireless communication system that performs environmental measurement, monitoring, control, and the like, there are many cases where the target area is relatively wide or there are many obstacles for wireless communication in the target area. In such a case, in order to cover the target area, even if it is not possible to communicate directly depending on the environment such as the installation position of the receiver and the transmitter and the radio wave condition, it is possible to perform communication by relaying other devices. It is advantageous to use a communication network.

  As this type of wireless communication network, a mesh network such as a wireless communication network using a Zigbee (registered trademark) protocol (see, for example, Patent Documents 1 and 2) has been proposed. In this mesh network, two-way communication between the coordinator and the router is performed by relaying directly to other routers in the communication area. One communication path is affected by multipath fading and communication is disabled. Even so, it is a technique that can search for another communication path and continue communication. Multipath fading refers to a phenomenon in which a received radio wave is canceled due to a phase difference generated between a plurality of communication radio wave reflection paths, and reception becomes impossible. In this mesh network, an end device such as a wireless sensor is connected to the lowermost router.

  In this mesh network, a large number of end devices placed at the end of the network are installed in the network, and the configuration is designed to be as simple as possible in order to operate by a battery. In general, a single antenna is used, and only transmission to the router is possible, but reception is not possible. For this reason, if multipath fading occurs due to movement of people in the installation environment, communication with the router cannot be continued.

  In Patent Document 3, when a communication node has a plurality of transmission antennas and communication with another communication node becomes impossible with one transmission antenna, the communication node is switched to another transmission antenna, The technology for continuing the communication is shown, and there is a description that the receiving antenna may be switched sequentially in the same manner.

  Although this Patent Document 3 does not mention a specific method in a case where the receiving antenna is sequentially switched, the data transmitted from other communication nodes is switched by sequentially switching the receiving antenna at a predetermined interval. In general, the reception method is adopted. When this method is applied to communication between a router and an end device in the mesh network described above, the receiving antenna in the router is sequentially switched at a predetermined interval to receive data sent from the end device at a predetermined cycle. become.

  For example, as shown in FIG. 24, when the router 1 has two antennas A and B, the antennas A and B are alternately switched at predetermined intervals, and the switched antennas are switched from the end device 2 to a predetermined cycle. It is assumed that the receiving antenna for the data transmitted at T. In this case, even if multipath fading occurs between the end device 2 and the antenna A, data from the end device 2 can be received by the antenna B.

JP 2006-5928 A JP 2006-42370 A JP 2006-352436 A

  However, if the router antenna is switched sequentially to receive data from the end device, the receiving antenna state is indefinite, and the communication path is extremely unstable in radio waves when communicating between routers. Will be put in a state. In this case, it can be avoided by retrying (transmission antenna switching) using a transmission diversity antenna, but there is a problem that the amount of communication due to the retry increases.

  The present invention has been made to solve such a problem, and the object of the present invention is to avoid multipath fading as a method of sequentially switching reception antennas, while reducing switching of reception antennas as a whole. An object of the present invention is to provide a wireless communication device capable of performing

  In order to achieve such an object, the present invention provides a wireless communication device that receives data transmitted at a predetermined transmission period from a registered transmission device, and includes a plurality of antennas and a plurality of antennas after activation. Reception antenna switching control means for sequentially switching at predetermined intervals and using the switched antenna as a reception antenna for data from the transmission device, and receiving data from the transmission device for each of the transmission devices (registered transmission devices) The optimal receiving antenna storage means for storing the receiving antenna that has succeeded as the optimal receiving antenna and the optimal receiving antenna storage means for storing the data from all of the transmitting devices (registered transmitting devices). Based on the optimal receive antenna for each transmitting device that is Base antenna determining means for determining any one of them as a base antenna, and when the base antenna is determined, the control for switching the receiving antenna by the receiving antenna switching control means is interrupted, and the determined base antenna is used as the receiving antenna. And receiving antenna fixing means for fixing.

  The wireless communication device of the present invention sequentially switches a plurality of antennas at predetermined intervals after activation, and uses the switched antennas as reception antennas for data from the transmission device. For example, when two antennas A and B are used as antennas, after startup, antenna A and antenna B are alternately switched, and the data from registered transmission devices is set with the switched antenna as a receiving antenna. Receive. Hereinafter, in order to simplify the description, two examples of the antenna A and the antenna B will be described.

[When the number of registered transmission devices is one]
As a minimum configuration, when the number of registered transmission devices is one, the wireless communication device of the present invention alternately switches between the antenna A and the antenna B, and receives data from one registered transmission device. Here, multipath fading has occurred between the transmitting device and the antenna A, and when the antenna A is selected as the receiving antenna, data from the transmitting device cannot be received, and the antenna B is used as the receiving antenna. It is assumed that data from the transmitting device can be received only when selected. In this case, antenna B is stored as the optimum receiving antenna of the transmitting device.

  If all the registered transmission devices, in this example, successfully receive data from one transmission device, based on the optimum reception antenna stored for this transmission device, the optimum reception antenna Any one of them is determined as a base antenna. In this case, antenna B is stored as the optimum receiving antenna of the transmitting device, and this antenna B is determined as the base antenna. Then, after the base antenna is determined, switching of the receiving antenna is interrupted, and the determined base antenna (antenna B) is fixed as the receiving antenna.

[When the number of registered transmission devices is two]
When the number of registered transmission devices is two, the wireless communication device of the present invention switches between antenna A and antenna B alternately after activation, and registers two transmission devices (first transmission device, first transmission device, Data from the second transmitting device). Here, when multipath fading occurs between the first and second transmitting devices and the antenna A, and when the antenna A is selected as the receiving antenna, the data from the first and second transmitting devices are It is assumed that data from the first and second transmitting devices can be received only when reception is not possible and antenna B is selected as the reception antenna. In this case, antenna B is stored as the optimal receiving antenna for the first and second transmitting devices.

  Then, if all of the registered transmission devices, in this example, successfully receive data from the first and second transmission devices, the optimum stored for the first and second transmission devices. Based on the receiving antenna, any one of the optimum receiving antennas is determined as the base antenna. In this case, antenna B is stored as the optimum receiving antenna of the first and second transmitting devices, and this antenna B is determined as the base antenna. Then, after the base antenna is determined, switching of the receiving antenna is interrupted, and the determined base antenna (antenna B) is fixed as the receiving antenna.

  When the number of registered transmission devices is two, multipath fading occurs between the first transmission device and antenna A and between the second transmission device and antenna B, and antenna A is selected as the reception antenna. Can receive data from the second transmitting device, but cannot receive data from the first transmitting device, and when antenna B is selected as the receiving antenna, A situation may be considered in which data from one transmitting device can be received, but data from a second transmitting device cannot be received.

  In this case, antenna B is stored as the optimal receiving antenna of the first transmitting device, antenna A is stored as the optimal receiving antenna of the second transmitting device, and both receive data from the first and second transmitting devices. If successful, based on the optimal receive antennas stored for the first and second transmitting devices, any one of the optimal receive antennas is determined as the base antenna. In this case, the antenna B is stored as the optimal reception antenna of the first transmission device, and the antenna A is stored as the optimal reception antenna of the second transmission device, and one of the antennas A and B, for example, Antenna A is determined as the base antenna. Then, after the antenna A is determined, switching of the receiving antenna is interrupted, and the determined base antenna (antenna A) is fixed as the receiving antenna.

  Here, the antenna A fixed as the receiving antenna cannot receive data from the first transmitting device. Therefore, in the present invention, the transmission cycle storage means for storing the transmission cycle of data from the transmission device, the transmission timing from the reception timing when data reception from the transmission device is successful, and the transmission cycle of data from the transmission device are used. Transmission timing calculating means for obtaining the next transmission timing of the data from the antenna, and an antenna used for receiving data from the transmitting device for a predetermined period before and after the next transmission timing obtained by the transmission timing calculating means If it is not the optimum receiving antenna of the device, receiving antenna forced switching control means for temporarily switching the antenna to the optimum receiving antenna of the transmitting device is provided. By providing such means, when the antenna A (base antenna) fixed as the receiving antenna receives data from the first transmitting device, the optimum receiving antenna (antenna B) of the first transmitting device. Can be temporarily switched to.

  According to the present invention, after startup, a plurality of antennas are sequentially switched at a predetermined interval, and the switched antennas are used as receiving antennas for data from the transmitting device, while each registered transmitting device is notified from the transmitting device. The reception antenna that has successfully received data shall be stored as the optimal reception antenna, and if reception of data from all of the registered transmission devices is successful, based on the stored optimal reception antenna of each transmission device. Since any one of the optimum receiving antennas is determined as the base antenna, the switching control of the receiving antenna is interrupted, and the determined base antenna is fixed as the receiving antenna. Turn off the receive antennas until you have successfully received data from all of the devices. After receiving all data from all registered transmitting devices, the receiving antenna is fixed to avoid multipath fading and reduce the switching of the receiving antenna as a whole. It becomes possible.

It is a block diagram which shows the outline of one Embodiment of the radio | wireless communications system using the radio | wireless communication device which concerns on this invention. It is a flowchart for demonstrating the receiving antenna control function which the router (receiving node) in this radio | wireless communications system has. It is a flowchart which shows the process of the base antenna switching control performed as a part of this receiving antenna control function. It is a flowchart which shows the reception process from the transmission node performed as a part of this receiving antenna control function. It is a flowchart which shows the process of the separate receiving antenna control performed as a part of this receiving antenna control function. It is a flowchart which shows the process of the transmission node state monitoring performed as a part of this receiving antenna control function. It is a figure which shows the example of installation of the end device (transmission node) in this radio | wireless communications system. It is a figure which shows a mode that the antenna A and the antenna B are switched alternately. It is a figure which shows the storage condition of the state of a transmission node to the state monitoring table before a transmission node is installed, the optimal receiving antenna, the elapsed time from the last reception, and the next transmission time. It is a figure which shows the storage condition of the state of the transmission node to the state monitoring table after the 1st transmission node was installed, the optimal receiving antenna, the elapsed time from the last reception, and the next transmission time. It is a figure which shows the control condition of a receiving antenna when the 1st transmission node is installed. It is a figure which shows the 1st example of the storing condition of the state of the transmission node to the state monitoring table after the 2nd transmission node was installed, the optimal receiving antenna, the elapsed time from the last reception, and the next transmission time. It is a figure which shows the control condition (1st example) of a receiving antenna when the 2nd transmission node is installed. It is a figure which shows the 2nd example of the storage condition of the state of a transmission node to the state monitoring table after the 2nd transmission node was installed, the optimal receiving antenna, the elapsed time from the last reception, and the next transmission time. It is a figure which shows the control condition (2nd example) of a receiving antenna when the 2nd transmission node is installed. It is a figure which shows the control condition of a receiving antenna when the antenna which can receive the data from a transmission node changes. It is a figure which shows the storage condition of the state of a transmission node to the state monitoring table when the antenna which can receive the data from a transmission node changes, the optimal reception antenna, the elapsed time from the last reception, and the next transmission time. After the antenna capable of receiving data from the transmitting node changes, the state of the transmitting node to the state monitoring table when the data is received by another antenna by the switching control of the receiving antenna, the optimal receiving antenna, It is a figure which shows the storage condition of the elapsed time from the last reception and the next transmission time. It is a figure which shows the control condition of a receiving antenna when a transmitting node disappears. It is a figure which shows the storage condition of the state of a transmission node to the state monitoring table when a transmission node disappears, the optimal receiving antenna, the elapsed time from the last reception, and the next transmission time. It is a figure which illustrates the reception condition of the data in a receiving node in case the registration number of a transmitting node is one. It is a figure which shows the control condition of the receiving antenna in this receiving condition. It is a functional block diagram of the principal part of a receiving node. It is a figure which illustrates the radio | wireless communications system using the router and end device which have a some receiving antenna.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an outline of an embodiment of a wireless communication system using a wireless communication device according to the present invention. 24, the same reference numerals as those in FIG. 24 denote the same or equivalent components as those described with reference to FIG. 24, and description thereof will be omitted.

  In this embodiment, the memory of the router 1 stores a data transmission period T from the end device 2 and the like. The router 1 is realized by hardware including a processor and a storage device, and a program for realizing various functions in cooperation with these hardware, and has a reception antenna control function as a function unique to this embodiment. is doing.

  In this embodiment, the end devices 2 registered for the router 1 are two end devices 2-1 and 2-2. In addition, the router 1 is referred to as a receiving node, and the end devices 2-1 and 2-2 are referred to as transmitting nodes. In this embodiment, the reception node 1 corresponds to the wireless communication device referred to in the present invention, and the transmission node 2 corresponds to the transmission device.

  Hereinafter, the receiving antenna control function of the receiving node 1 will be described with reference to the flowcharts shown in FIGS. After starting up (FIG. 2: step S101), the receiving node 1 sets the state (monitoring state) of all registered transmitting nodes to “waiting for notification” (step S102), and starts control of the receiving antenna (step S102). S103). In the control of the receiving antenna, the processes according to the flowcharts shown in FIGS. 3 to 6 are sequentially executed while being correlated with each other.

[None of sending nodes 2-1 and 2-2 are installed]
Assume that the transmission nodes 2-1 and 2-2 are not installed as a state before the operation is started (see FIG. 7A). In this case, the receiving node 1 starts the base antenna switching control whose flowchart is shown in FIG. 3 while the state of the transmitting nodes 2-1 and 2-2 is “waiting for notification”.

  In this base antenna switching control, the receiving node 1 checks whether or not the status of all registered transmitting nodes is “notifying continuing” (step S201). In this case, since the state of the transmission nodes 2-1 and 2-2 is “notification waiting”, the process proceeds to step S202 and subsequent steps according to NO in step S201. In the processing after step S202, reception antenna switching control is performed.

[Reception antenna switching control]
In step S202, the receiving node 1 checks whether or not the current receiving antenna is the final antenna (antenna B), and if it is not the final antenna (antenna B) (NO in step S202), that is, if it is the antenna A. For example, the reception antenna is switched to the next antenna (antenna B) (step S203).

  Then, counting of the next antenna switching timing is started (step S205). When the next antenna switching timing is reached (YES in step S206), it is confirmed that the state of all the transmission nodes is not “notifying continuation” (step S201). NO), the process returns to step S202.

  In this case, since the current receiving antenna is the antenna B (YES in step S202), the receiving antenna is switched to the top antenna (antenna A) (step S204). Then, counting of the next antenna switching timing is started (step S205). When the next antenna switching timing is reached (YES in step S206), it is confirmed that the state of all the transmission nodes is not “notifying continuation” (step S201). NO), the process returns to step S202 again.

  Thereafter, by repeating the same operation, the receiving node 1 alternately switches between the antenna A and the antenna B, as shown in FIG. Receiving antenna). In this embodiment, it is assumed that the reception node 1 switches the reception antenna at the same cycle as the data transmission cycle T from the transmission node 2.

[When transmission node 2-1 is installed]
In this state, it is assumed that the transmission node 2-1 is installed and data transmission from the transmission node 2-1 is started. In this case, data from the transmission node 2-1 can be received only by the antenna B (see FIG. 7B).

  As described above, the reception node 1 waits for reception of data from the transmission node 2 while alternately switching reception antennas (FIG. 4: step S301). Here, when the data from the transmission node 2-1 is received (YES in step S302), the state of the transmission node 2-1 is set to “continuing notification” (step S303), and the reception antenna at that time (current reception antenna) Is stored as the optimum receiving antenna of the transmitting node 2-1 (step S304).

  The reception node 1 sets the reception timing of the data as the final reception of the data from the transmission node 2-1, and starts measuring the elapsed time TMR from the final reception (step S305). Further, the next data transmission time trnext from the transmission node 2-1 is obtained from the final reception timing and the transmission cycle T, and the obtained transmission time trnext is stored as the next transmission time (step S306).

  In FIG. 9, the memory of the transmission node state, the optimal reception antenna, the elapsed time TMR from the last reception, and the next transmission time trnext associated with each registered transmission node before the transmission node 2-1 is installed. The storage status in the internal table TB1 (hereinafter, this table is referred to as a status monitoring table) is shown.

  Before the transmission node 2-1 is installed, the transmission node NO. Are “# 1” and “# 2”, and the state of the transmission node is “waiting for notification”. Since the optimum reception antenna, the elapsed time TMR from the last reception, and the next transmission time trnext have not yet been obtained, they are set to “−”.

  FIG. 10 shows the state of the transmitting node associated with each registered transmitting node when the transmitting node 2-1 is installed, the optimal receiving antenna, the elapsed time TMR from the last reception, and the state of the next transmission time trnext. The storage status in the monitoring table TB1 is shown.

  When data from the transmission node 2-1 is received, the state of the transmission node 2-1 is set to “continuing notification” in the state monitoring table TB 1, and the optimum reception antenna of the transmission node 2-1 is stored as the antenna B. Then, the elapsed time TMR from the last reception of the transmission node 2-1 is stored as TMR1, and the next transmission time trnext of the transmission node 2-1 is stored as tr1next.

  The elapsed time TMR1 from the last reception of the transmission node 2-1 is reset every time data is received from the transmission node 2-1, and the time measurement is restarted. The next transmission time tr1next of the transmission node 2-1 is updated every time data from the transmission node 2-1 is received.

  FIG. 11 shows a control state of the reception antenna when the transmission node 2-1 is installed. In this example, since the data from the transmission node 2-1 can be received only by the antenna B, when the antenna A is selected as the reception antenna, the data from the transmission node 2-1 cannot be received (t1 Point), when the antenna B is selected as the receiving antenna, data from the transmitting node 2-1 is received (point t2). In addition, since the state of the transmission node 2-2 in the state monitoring table TB1 remains “waiting for notification”, the determination result in step S201 in the base antenna switching control shown in FIG. Switching control continues.

  While continuing this reception antenna switching control, the reception node 1 checks the next transmission time tr1next of the transmission node 2-1 stored in the state monitoring table TB1 (FIG. 10), and the reception antenna at the next transmission time trnext1 is checked. If it is not the optimum reception antenna (antenna B) of the transmission node 2-1, the antenna is temporarily switched to the optimum reception antenna (antenna B) of the transmission node 2-1 (see points t3 and t5 shown in FIG. 11).

  The receiving node 1 performs the temporary switching (forced switching) of the receiving antenna by the individual receiving antenna control whose flowchart is shown in FIG. In this individual reception antenna control, the reception node 1 sets α as a predetermined time width, and when the current time reaches the next transmission time tr1next-α of the transmission node 2-1 (YES in step S401), The receiving antenna is stored (step S402).

  Now, let the next transmission time tr1next be the point t3 shown in FIG. In this case, the reception node 1 stores the current reception antenna A when the current time reaches the next transmission time t3-α (YES in step S401). Then, it is confirmed that the current receiving antenna A is not the optimum receiving antenna (antenna B) of the transmitting node 2-1 (NO in step S403), and the receiving antenna is changed to the optimum receiving antenna (antenna B) of the transmitting node 2-1. Switching (step S404).

  Then, when the current time reaches the next transmission time t3 + α (YES in step S405), it is confirmed that the current receiving antenna (antenna B) is not the receiving antenna (saved receiving antenna (antenna A)) stored in step 402. (NO in step S406), the reception antenna is switched to the storage reception antenna (antenna A) (step S407). Then, the next transmission time tr1next of the transmission node 2-1 is updated as t4 (step S408), and the process returns to step S401.

  When the current time reaches the next transmission time t4-α (YES in step S401), the receiving node 1 stores the current receiving antenna B. In this case, since the current receiving antenna B is the optimum receiving antenna (antenna B) of the transmitting node 2-1 (YES in step S 403), the receiving antenna is not forcibly switched. When the current time reaches the next transmission time t4 + α, it is checked whether or not the current reception antenna is a storage reception antenna (step S406). In this case, the current reception antenna is the antenna B, which is the same as the storage reception antenna (antenna B), so that the process does not proceed to step S407, and the next transmission time tr1next of the transmission node 2-1 is updated as t5 (step S407). S408), the process returns to step S401.

[When transmission node 2-2 is installed]
In this state, it is assumed that the transmission node 2-2 is further installed and data transmission from the transmission node 2-2 is started. In this case, data from the transmission node 2-2 can be received only by the antenna B (see FIG. 7C).

  As described above, the reception node 1 waits for reception of data from the transmission node 2 while alternately switching reception antennas (FIG. 4: step S301). Here, when data from the transmission node 2-2 is received (YES in step S302), the state of the transmission node 2-2 is set to “notifying continuing” (step S303), and the reception antenna at that time (current reception antenna) Is stored as the optimum receiving antenna of the transmitting node 2-2 (step S304).

  The reception node 1 sets the reception timing of the data as the final reception of the data from the transmission node 2-2, and starts counting the elapsed time TMR from the final reception (step S305). Further, the next data transmission time trnext from the transmission node 2-2 is obtained from the final reception timing and the transmission cycle T, and the obtained transmission time trnext is stored as the next transmission time (step S306).

  FIG. 12 shows the state of the transmission node associated with each registered transmission node when the transmission node 2-2 is installed, the optimal reception antenna, the elapsed time TMR from the last reception, and the next transmission time trnext. The storage status in the monitoring table TB1 is shown.

  When data from the transmission node 2-2 is received, in the state monitoring table TB1, the state of the transmission node 2-2 is set to “continuing notification”, and the optimum reception antenna of the transmission node 2-2 is stored as the antenna B. The elapsed time TMR from the last reception of the transmission node 2-2 is stored as TMR2, and the next transmission time trnext of the transmission node 2-2 is stored as tr2next.

  The elapsed time TMR2 from the last reception of the transmission node 2-2 is reset every time data is received from the transmission node 2-2, and the time measurement is restarted. The next transmission time tr2next of the transmission node 2-2 is updated every time data from the transmission node 2-1 is received.

  FIG. 13 shows a control state of the reception antenna when the transmission node 2-2 is installed. In this example, since the data from the transmission node 2-2 can be received only by the antenna B, the data from the transmission node 2-2 cannot be received when the antenna A is selected as the reception antenna (t2 Point), when the antenna B is selected as the receiving antenna, data from the transmitting node 2-2 is received (point t4).

  Further, when the data from the transmission node 2-2 is received by the antenna B, the states of the transmission nodes 2-1 and 2-2 in the state monitoring table TB1 are both “notifying continuing”, and the base shown in FIG. The determination result in step S202 in the antenna switching control is YES, and the process proceeds to step S207 and subsequent steps. In the processing after step S207, the receiving antenna is fixed.

[Fixing the receiving antenna]
In fixing the reception antenna, the reception node 1 determines a base antenna by majority vote based on the optimum reception antenna of each transmission node in the state monitoring table TB1 (step S207). In the case of the same number, either one is used as a base antenna. In this example, since the optimal receiving antennas of the transmission nodes 2-1 and 2-2 are both the antenna B, the antenna B is determined as the base antenna.

  Then, the reception node 1 checks whether or not the current reception antenna is the determined base antenna (step S208), and if the current reception antenna is not the determined base antenna (NO in step S208), The receiving antenna is switched to the determined base antenna (step S209). If the current receiving antenna is the determined base antenna (YES in step S208), the receiving antenna is not switched and the current receiving antenna remains unchanged. As a result, the reception antenna switching control up to that point is interrupted, and the reception antenna in the reception node 1 is fixed to the base antenna (antenna B) determined in step S207.

  In this way, the reception antenna switching control is performed until the data reception of the transmission nodes 2-1 and 2-2 is successful, and after the data reception from the transmission nodes 2-1 and 2-2 is successful. The reception antenna is fixed, and switching of the reception antenna is reduced as a whole while avoiding multipath fading.

  In the example described above, the data from the transmission nodes 2-1 and 2-2 can be received only by the antenna B, but the data from the transmission node 2-1 can be received only by the antenna B. It is also conceivable that data from the transmission node 2-2 can be received only by the antenna A (see FIG. 7D).

  FIG. 14 shows the state of the transmission node associated with each registered transmission node in this case, the optimum reception antenna, the elapsed time TMR from the last reception, and the storage status of the next transmission time trnext in the state monitoring table TB1. Show.

  When data from the transmission node 2-2 is received, the state of the transmission node 2-2 is set to “notification continuing”, the optimum reception antenna of the transmission node 2-2 is stored as the antenna A, and the transmission node 2- 2 is stored as TMR2, and the next transmission time trnext of the transmission node 2-2 is stored as tr2next.

  FIG. 15 shows the control status of the receiving antenna in this case. In this example, since the data from the transmission node 2-2 can be received only by the antenna A, the data from the transmission node 2-2 cannot be received when the antenna B is selected as the reception antenna (t3 Point), when the antenna A is selected as the receiving antenna, the data from the transmitting node 2-2 is received (t5 point).

  Further, when the data from the transmission node 2-2 is received by the antenna A, the states of the transmission nodes 2-1 and 2-2 in the state monitoring table TB1 are both “notifying continuing”, and the base shown in FIG. The determination result in step S202 in the antenna switching control is YES, the process proceeds to step S207 and subsequent steps, and the receiving antenna is fixed.

  In fixing the reception antenna, the reception node 1 determines a base antenna by majority vote based on the optimum reception antenna of each transmission node in the state monitoring table TB1 (step S207). In the case of the same number, either one is used as a base antenna. In this example, the optimal reception antenna of the transmission node 2-1 is the antenna B, and the optimal reception antenna of the transmission node 2-2 is the antenna A. Therefore, one of the antennas A and B is determined as the base antenna. In this example, the antenna A is determined as the base antenna.

  Then, the reception node 1 checks whether or not the current reception antenna is the determined base antenna (step S208), and if the current reception antenna is not the determined base antenna (NO in step S208), The receiving antenna is switched to the determined base antenna (step S209). If the current receiving antenna is the determined base antenna (YES in step S208), the receiving antenna is not switched and the current receiving antenna remains unchanged. Thereby, the switching control of the receiving antenna is interrupted, and the receiving antenna in the receiving node 1 is fixed to the base antenna (antenna A) determined in step S207.

  During the fixing of the receiving antenna, the receiving node 1 performs the next time based on the next transmission times tr1next and tr2next of the transmitting nodes 2-1 and 2-2 in the state monitoring table TB1 by the above-described individual receiving antenna control (FIG. 5). If the reception antennas at the transmission times trnext1 and tr2next are not the optimal reception antennas of the transmission nodes 2-1 and 2-2, the antennas are temporarily switched to the optimal reception antennas of the transmission nodes 2-1 and 2-2.

  In this case, since the receiving antenna is fixed to the antenna A that is the optimum receiving antenna of the transmitting node 2-2, the next transmitting time tr1next (t4, t6, t8, t10 points of the transmitting node 2-1 is controlled by the individual receiving antenna control. The reception antenna is forcibly switched from the antenna A to the antenna B in a period of ± α centering around). In this case, the optimum reception antenna of the transmission node 2-2 is the antenna A, which is not necessary, so that the antenna is not forcibly switched.

  In this way, the reception antenna switching control is performed until the data reception of the transmission nodes 2-1 and 2-2 is successful, and after the data reception from the transmission nodes 2-1 and 2-2 is successful. The receiving antenna is fixed except for a slight period (several seconds) of ± α centered on the transmission timing of data from the transmitting node 2-1, and avoids multipath fading, and as a whole the receiving antenna Switching is reduced.

[When the antenna that can receive data from the transmitting node changes]
Here, it is assumed that the state of multipath fading has changed and the antenna that can receive data from the transmission node 2-1 has changed from antenna B to antenna A (see FIG. 7E). In this case, reception of data from the transmission node 2-1 is always performed using the antenna B as the reception antenna, but reception by this antenna B cannot be performed (see points t3 and t5 shown in FIG. 16).

  The receiving node 1 monitors the states of the transmitting nodes 2-1 and 2-2 based on the elapsed times TMR1 and TMR2 from the last reception of the transmitting nodes 2-1 and 2-2 in the state monitoring table TB1. . FIG. 6 is a flowchart of the state monitoring of the transmitting node based on the elapsed time TMR from this final reception.

  The receiving node 1 checks the elapsed times TMR1 and TMR2 from the last reception of the transmitting nodes 2-1 and 2-2 according to this flowchart (step S501), and the elapsed times TMR1 and TMR2 are predetermined times. When TX has elapsed (YES in step S502), the monitoring state of the transmission nodes 2-1 and 2-2 is changed from “notification continuing” to “waiting for notification”. The predetermined time TX is set to be longer than the data transmission cycle T. In this example, 2T <TX <3T, and the time for which two retries are anticipated.

  In this case, the data from the transmission node 2-1 cannot be received, and the elapsed time TMR1 from the final reception of the transmission node 2-1 exceeds TX (YES in step S502, t6 shown in FIG. 16). 1 changes the monitoring state of the transmission node 2-1 from “notification ongoing” to “waiting for notification”. Thereby, in the state monitoring table TB1, as shown in FIG. 17, the state of the transmission node 2-1 becomes “waiting for notification”.

  For this reason, in the base antenna switching control (FIG. 3), the state of all transmitting nodes does not become “notifying continuously” (NO in step S201), and the receiving node 1 resumes the switching control of the receiving antenna. When the receiving antenna is switched to the antenna B by resuming the switching control of the receiving antenna, by the individual receiving antenna control, the next transmission time tr2next (point t9 shown in FIG. 16) of the transmission node 2-2 is ± α. The reception antenna is temporarily switched to antenna A, and data from the transmission node 2-2 is received.

  Then, when the receiving antenna is switched to the antenna A by the switching control of the receiving antenna, the data reception from the transmitting node 2-1 is successful (point t10 shown in FIG. 16). At this time, as shown in FIG. 18, the reception node 1 stores the state of the transmission node 2-1 as “notifying continuing” and stores the optimum reception antenna of the transmission node 2-1 as the antenna A in the state monitoring table TB1. To do. Further, the elapsed time TMR from the last reception of the transmission node 2-1 is stored as TMR1, and the next transmission time trnext of the transmission node 2-1 is stored as tr1next.

  At this time, the state of all the transmission nodes becomes “notifying continuously” (YES in step S201), and the reception node 1 fixes the reception antenna. In this case, since the optimum receiving antennas of the transmitting nodes 2-1 and 2-2 are both the antenna A, the antenna A is determined as a base antenna by majority vote, and the determined base antenna (antenna A) is fixed as the receiving antenna. . Thereafter, data from the transmission nodes 2-1 and 2-2 is received by the fixed reception antenna A. In this case, the optimal reception antenna of the transmission nodes 2-1 and 2-2 is the antenna A, which is not necessary, so that the antenna is not forcibly switched.

[When sending node disappears]
Here, it is assumed that the transmission node 2-2 disappears due to a failure or the like (see FIG. 7F). In this case, reception of data from the transmission node 2-2 is always performed using the antenna A as the reception antenna, but reception by the antenna A is not performed (see points t6 and t8 shown in FIG. 19).

  In this case, data from the transmission node 2-2 is not received, and the elapsed time TMR2 from the last reception of the transmission node 2-2 exceeds TX (YES in step S502, t9 shown in FIG. 19). 1 shifts the monitoring state of the transmission node 2-2 from “notification continuing” to “waiting for notification”. Thereby, in the state monitoring table TB1, as shown in FIG. 20, the state of the transmission node 2-2 becomes “waiting for notification”.

  For this reason, in the base antenna switching control (FIG. 3), the state of all transmitting nodes does not become “notifying continuously” (NO in step S201), and the receiving node 1 resumes the switching control of the receiving antenna. When the reception antenna is switched to the antenna B by resuming the switching control of the reception antenna, the reception antenna is temporarily switched to the antenna A by the individual reception antenna control (see point t10 shown in FIG. 19). In this case, when the reception antenna is switched to the antenna A, the optimum reception antenna of the transmission node 2-1 is the antenna A, and is not necessary, so the antenna is not forcibly switched.

  Thereafter, this state continues until data from the transmission node 2-2 is received. Even when the transmission node 2-2 is re-installed, the reception antenna is alternately switched between the antenna A and the antenna B by the switching control of the reception antenna. Data can be received.

  In the above-described embodiment, for simplicity of explanation, the transmission node 2 registered in the reception node 1 is two of the transmission nodes 2-1 and 2-2, but is limited to two. Instead, more transmitting nodes 2 may be registered. Further, as a minimum configuration, there may be one transmission node 2 registered in the reception node 1.

[When the number of registered transmission nodes is one]
When there is one transmission node 2 registered in the reception node 1, the reception node 1 alternately switches the antenna A and the antenna B as reception antennas by switching control of the reception antennas.

  Here, as shown in FIG. 21, multipath fading has occurred between the transmission node 2 and the antenna A, and data from the transmission node 2 can be received when the antenna A is selected as the reception antenna. It is assumed that the data from the transmission node 2 could be received when the antenna B was selected as the receiving antenna (t2 shown in FIG. 22).

  In this case, the reception node 1 sets the state of the transmission node 2 to “notifying continuing” and stores the antenna B as the optimal reception antenna of the transmission node 2. Then, it is determined that the statuses of all registered transmission nodes are “notifying continued”, and the receiving antenna is fixed. In this case, since the optimal reception antenna of the transmission node 2 is stored as the antenna B, the antenna B is determined as the base antenna. Then, after determining the base antenna, the switching control of the receiving antenna is interrupted, and the determined base antenna (antenna B) is fixed as the receiving antenna.

  In the above-described embodiment, the switching cycle between the receiving antenna A and the receiving antenna B is the same as the data transmission cycle T from the transmission node 2, but it is not necessarily the same cycle. The period may be longer than the data transmission period T, or may be shorter.

  In the above-described embodiment, the reception antenna provided in the reception node 1 is two reception antennas A and B. However, the configuration can be similarly made when more reception antennas are provided. .

  FIG. 23 shows a functional block diagram of the main part of the receiving node 1. The receiving node 1 switches the antennas A and B alternately after activation, the receiving antenna switching control unit 1A using the switched antenna as a receiving antenna for data from the transmitting node, and each of the registered transmitting nodes. An optimal receiving antenna storage unit 1B that stores a receiving antenna that has successfully received data from the transmitting node as an optimal receiving antenna, and an optimal receiving antenna storage unit that has received data from all of the registered transmitting nodes. Based on the optimum reception antenna of each transmission node stored in 1B, any one of the optimum reception antennas is determined as a base antenna by majority vote (in the case of the same number, one of antennas A and B). When the base antenna determination unit 1C and the base antenna are determined, the reception antenna switching control unit 1A It interrupts the switching control signal antenna, and a receiving antenna fixing unit 1D for fixing the determined base antenna as the receiving antenna.

  In addition, the receiving node 1 fixes the receiving antenna to the base antenna by the receiving antenna fixing unit 1D, and receives data from the transmitting node for each registered transmitting node within a predetermined time TX after receiving data from the transmitting node. A reception antenna that restarts the reception antenna switching control by the reception antenna switching control unit 1A when it is not possible to confirm the transmission of the next data within a predetermined time TX. The switching control restarting unit 1E, the transmission cycle storage unit 1F for storing the transmission cycle T of data from the transmission node, the reception timing when the data reception from the transmission node is successful, and the transmission cycle T of the data from the transmission node A transmission timing calculation unit 1G for obtaining a next transmission timing trnext of data from the transmission node from the transmission node, and a transmission timing calculation unit If the antenna used to receive data from the transmission node is not the optimal reception antenna of the transmission node for a predetermined period (trnext ± α) including the next transmission timing trnext obtained by G, the antenna is designated as the transmission node And a receiving antenna forced switching control unit 1H that temporarily switches to the optimum receiving antenna.

  In this reception node 1, the optimum reception antenna storage unit 1B stores data from the transmission node that has become unable to confirm data transmission after the reception antenna switching control restarting unit 1E restarts the reception antenna switching control. Is successfully stored as the optimum reception antenna of the transmission node.

  The wireless communication device of the present invention can be used in various fields such as a medium-scale and large-scale monitoring and control system having a mesh network structure with a communication trunk line. More specifically, it can be used for an indoor air conditioning system by VAV (variable air volume adjustment).

  DESCRIPTION OF SYMBOLS 1 ... Router (reception node), A, B ... Reception antenna, 2 (2-1, 2-2) ... End device (transmission node), TB1 ... Table (status monitoring table), 1A ... Reception antenna switching control part, DESCRIPTION OF SYMBOLS 1B ... Optimal receiving antenna memory | storage part, 1C ... Base antenna determination part, 1D ... Reception antenna fixing | fixed part, 1E ... Reception antenna switching control restart part, 1F ... Transmission period memory | storage part, 1G ... Transmission timing calculating part, 1H ... Reception antenna forced Switching control unit.

Claims (4)

In a wireless communication device that receives data transmitted at a predetermined transmission cycle from a registered transmission device,
Multiple antennas,
After startup, the plurality of antennas are sequentially switched at a predetermined interval, and the switched antenna is a reception antenna switching control means for receiving data from the transmitting device.
Optimal receiving antenna storage means for storing, as an optimal receiving antenna, a receiving antenna that has successfully received data from the transmitting device for each of the transmitting devices;
When the reception of data from all of the transmission devices is successful, based on the optimum reception antenna of each transmission device stored in the optimum reception antenna storage means, based on any one of the optimum reception antennas Base antenna determining means for determining as an antenna;
Receiving antenna fixing means for interrupting the switching control of the receiving antenna by the receiving antenna switching control means when the base antenna is determined, and fixing the determined base antenna as the receiving antenna. Communication device. The wireless communication device of claim 1, wherein
While the receiving antenna is fixed to the base antenna by the receiving antenna fixing means, for each of the transmitting devices, it is checked whether or not the next data is transmitted within a predetermined time after receiving data from the transmitting device. And receiving antenna switching control resuming means for resuming switching control of the receiving antenna by the receiving antenna switching control means when the transmission of the next data cannot be confirmed within a predetermined time. Wireless communication device. The wireless communication device of claim 2, wherein
The optimum receiving antenna storage means includes
After resuming the switching control of the receiving antenna by the receiving antenna switching control restarting means, if the data transmission from the transmitting device that can no longer confirm the data transmission is successful, the reception of the data successfully received A wireless communication device, wherein the antenna is updated and stored as an optimum receiving antenna of the transmitting device. The wireless communication device according to any one of claims 1 to 3,
Transmission period storage means for storing a transmission period of data from the transmission device;
A transmission timing calculation means for obtaining a next transmission timing of data from the transmission device from a reception timing when data reception from the transmission device is successful and a transmission cycle of data from the transmission device;
If the antenna used to receive data from the transmitting device is not the optimum receiving antenna of the transmitting device for a predetermined period before and after the next transmitting timing obtained by the transmitting timing calculating means, the antenna is set to the transmitting device. A wireless communication device comprising: a reception antenna forced switching control means for temporarily switching to an optimal reception antenna.

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