JP5143537B2 - Wireless communication system - Google Patents

Description

  The present invention relates to a wireless communication system including a data aggregating apparatus and a number of terminal stations connected to the aggregating apparatus so as to be able to perform wireless communication.

  Using a wireless communication system including an aggregation device such as a data collection server and a terminal station connected to the aggregation device so as to be able to perform wireless communication, various data acquired on the terminal station side is collected by the aggregation device. It is known. For example, Patent Literature 1 discloses that such a wireless communication system is applied to an automatic meter reading system that regularly collects meter reading data of a water meter.

In collecting meter reading data and the like, it is important to ensure that all of the periodic data reaches the aggregation device. For this reason, in order to check the arrival of data, when data arrives from the terminal station to the aggregation device, an ACK (Acknowledgment: acknowledgment) is transmitted as a response signal from the aggregation device to the terminal station in response to this. Techniques are known. Also, the aggregation device performs a process to check whether data has arrived from all the terminal stations within a predetermined period. When there is unarrival data, a data transmission request signal is transmitted from the aggregation device to the terminal station. Techniques for doing this are also known.
JP 2002-92776 A

  However, in a wireless communication system with a large number of terminal stations, when the data arrival confirmation method for transmitting the ACK or the data transmission request is adopted, the processing load of the aggregation device increases or communication traffic increases. Therefore, there is a concern that smooth data collection cannot be performed. In particular, when a wireless communication path is adopted in which a large number of terminal stations are connected to a network in a tree shape having a plurality of hierarchies, and a so-called bucket relay system is used for communication along the tree hierarchies. The conventional confirmation method is not desirable because there is a demand to suppress the processing load and communication traffic as much as possible.

  The present invention has been made in view of such circumstances, and provides a wireless communication system capable of reliably collecting necessary data in the aggregation device without increasing the processing load and communication traffic of the aggregation device The purpose is to do.

The wireless communication system according to the present invention includes an aggregation device that collects data acquired at a predetermined period of time, and is connected to the aggregation device so as to be capable of wireless communication , and the data and the data are connected to the aggregation device. A plurality of terminal stations that periodically transmit time data that is the acquisition time of the data, and the aggregation device periodically receives the data from each terminal station in response to the reception of the data. A data confirming unit for confirming , which is obtained at each time by comparing the interval between the time data attached to the data received this time and the time data attached to the data received last time and the period. that a data check unit for detecting missing and lost time that the data, when the missing of the data is confirmed for a particular end station by the data checking section, the missing time to the specific terminal station A retransmission request unit which generates a communication signal for requesting retransmission of data corresponding to you comprising a.

According to this configuration, data loss is confirmed when data is received by the aggregation device, and a data retransmission request is sent only to a terminal station having a loss. For this reason, there is no need to regularly check the data reception status of all the terminal stations in the aggregation device, and the processing load of the aggregation device can be reduced. In addition, even if a temporary failure or the like occurs on the communication line and the data does not reach, a wasteful data transmission request is not transmitted from the aggregation device side (in the first case, this data transmission request is Since the data retransmission request is transmitted only to a specific terminal station on the assumption that the communication path is secured, the communication traffic can be suppressed to the minimum.

Further, it is possible to easily finding by using the time data that can verify the periodic property. For example, when there is a time data interval exceeding 30 minutes between the data acquired this time and the data acquired last time, even though the data should be acquired every 30 minutes, the data is missing. Can be recognized as occurring.

In the above configuration, the terminal station, it is not to demand that is networked to a tree having a plurality of hierarchies.

  When terminal stations are connected to a network in the form of a tree having multiple hierarchies, data can be collected in a shorter time than when polling each terminal station individually from the aggregation device. This is advantageous for communication systems. However, since the number of terminal stations to be covered is large, the processing load of the aggregation device tends to be heavy, and further suppression of communication traffic is required. For this reason, it is suitable as an application of the present invention having the above-mentioned advantages.

In any of the above-described configurations, each terminal station can acquire meter-reading data from a metering device for electric energy, and the data transmitted from each terminal station to the aggregation device is stored in each terminal station. it is not to demand an acquired meter reading data is in.

  According to this configuration, it is possible to construct an automatic meter-reading system that periodically collects meter-reading data of power consumption while suppressing the processing load and communication traffic of the aggregation device using the wireless communication system according to the present invention. .

  ADVANTAGE OF THE INVENTION According to this invention, the processing load of an aggregation apparatus can be reduced and the communication traffic between an aggregation apparatus and a terminal station can be suppressed. Therefore, it is possible to provide a wireless communication system capable of reliably collecting necessary data by the aggregation device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing an overall configuration of a wireless communication system according to an embodiment of the present invention. This wireless communication system is applied to an automatic meter-reading system that automatically collects meter-reading data of power usage from a large number of power consumers, and includes a collection server SV and a gateway GW (aggregation device), It is composed of terminal stations A, B, C.

  Terminal stations A, B, C,... Are wireless communication terminal stations that are capable of wireless communication with the gateway GW and other terminal stations. Is periodically transmitted to the gateway GW. In this embodiment, each terminal station A, B, C... Performs wireless communication in a PHS (Personal Handyphone System) transceiver mode. Further, the terminal stations A, B, C... Are network-connected in a tree shape having a plurality of hierarchies.

  The collection server SV is installed at, for example, a business office of an electric power company, and collects the meter reading data from each terminal in order to calculate the electric power charge of each electric power consumer. The collection server SV is network-connected to other business servers, management servers, control servers, etc. (not shown), and operates in cooperation with other businesses. The collection server SV holds a route table indicating how the gateway GW and the terminal stations A, B, C... Are arranged, and the gateway GW, the terminal stations A, B, C. Data communication with each of them is possible.

  The gateway GW is connected to the collection server SV via a network such as an in-house optical fiber network, and the PHS wireless communication network configured by the terminal stations A, B, C... Is connected to the collection server SV. A device that interconnects an optical fiber communication network. According to the route table, the terminal stations A and H are arranged in the lower layer of one gateway GW, the terminal stations B and C are arranged in the lower layer of the terminal station A, and the lower stations of the terminal stations B and C are respectively in the lower layer. The terminal stations D and E and the terminal stations F and G are arranged so that a tree-like PHS wireless communication network is formed.

  As described above, the meter reading data is periodically transmitted from the terminal stations A, B, C... Toward the collection server SV. On the other hand, control data such as a request signal for backup meter reading data, which will be described later, and an open / close control signal for the switch 25 (FIG. 3) are transmitted from the collection server SV to the terminal stations A, B, C. The

  FIG. 2 is a time chart showing a data transmission / reception state between the collection server SV (gateway GW) and the terminal stations A, B, C, D, E, F, and G constituting one tree. When the collection server SV receives meter reading data, the terminal stations D and E in the lowermost layer respectively transmit their meter reading data to the terminal station B in the middle layer when a predetermined transmission timing arrives. Similarly, the terminal stations F and G in the lowermost layer transmit their own meter reading data to the terminal station C. Next, the terminal station B transmits its own meter reading data and the meter reading data of the terminal stations D and E received earlier to the terminal station A in the upper layer. Similarly, the terminal station C transmits its own meter reading data and the meter reading data of the terminal stations F and G received earlier to the terminal station A in the upper layer. Thereafter, the terminal station A transmits its own meter reading data and the meter reading data of the terminal stations B to G previously received to the collection server SV via the gateway GW.

  On the other hand, when the control data is transmitted from the collection server SV, the data is transmitted through the reverse route at the time of reception. For example, when control data is transmitted from the collection server SV to the terminal station E, a wireless communication path that sequentially passes through the gateway GW, the terminal station A, and the terminal station B is used.

  In this way, a large number of terminal stations A, B, C... Are connected to a network in the form of a tree having a plurality of hierarchies, and data transmission is performed in a so-called bucket relay system, thereby collecting server SV (gateway GW). Therefore, data can be collected in a shorter time than when polling each terminal individually. Data transmission does not have to be fixed in such a bucket relay type, and if necessary, the hierarchy can be skipped and wireless communication can be performed between the terminal stations, or directly between the gateway GW and the lower-layer terminal station. Wireless communication may be performed, or direct wireless communication may be performed with a terminal station belonging to another gateway GW.

  Next, the functional configuration of the collection server SV and one terminal station A will be described based on the block diagram shown in FIG. The collection server SV functionally includes a transmission / reception unit 11, a control unit 12, a data confirmation unit 13, a retransmission request unit 14, and a data storage unit 15. Further, the terminal station A includes a transmission / reception unit 21, a control unit 22, and a backup memory 23. The terminal station A includes a watt-hour meter 24 that measures the amount of power used by a power consumer in which the terminal station A is disposed, and an open / close that switches ON / OFF of power supply from the commercial power transmission system to the power consumer. As the terminal unit UT combined with the device 25, it is arranged in the electric power consumer. The same applies to the other terminal stations B, C.

  The transmission / reception unit 11 is a functional unit that performs data communication with a number of terminal stations A, B, C,... Via the gateway GW. While the transmission / reception unit 11 receives the meter reading data of the watt-hour meter 24 periodically transmitted from the terminal stations A, B, C..., For the terminal stations A, B, C. Control data such as a request signal for backup meter reading data and an open / close control signal for the switch 25 are transmitted.

  The control unit 12 includes a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores a control program, a RAM (Random Access Memory) that is used as a work area of the CPU, and the CPU executes the control program. This controls the operation of each part of the collection server SV. The control unit 12 controls transmission / reception processing of the transmission / reception unit 11, arithmetic processing in the data confirmation unit 13 and retransmission request unit 14, storage processing in the data storage unit 15, and the like.

  The data confirmation unit 13 confirms the periodic arrival status of the meter reading data from the terminal stations A, B, C... When the meter reading data is received by the transmission / reception unit 21. FIG. 4 is a data configuration diagram of meter-reading data transmitted from each terminal station A, B, C... To the collection server SV. The meter reading data includes “instrument ID”, “meter reading date and time”, “instruction value”, and “data flag”. “Instrument ID” is a unique ID number assigned to the electricity meter 24 for each power consumer. The “meter reading date and time” is time data indicating the date and time when the meter reading data is acquired. The “instruction value” is an instruction value of the integrated electric energy measured by the watt hour meter 24. The “data flag” is data indicating information such as whether or not the instruction value is properly read in a flag format. Such meter reading data is transmitted from each terminal station A, B, C... To the collection server SV at a predetermined cycle, for example, every 30 minutes.

  The data check unit 13 uses the above “meter reading date” (additional data), and for each terminal station A, B, C... Is compared with the meter reading data recorded in the data storage unit 15 as the preceding data (previously received data) and the continuity is confirmed to confirm the lack of meter reading data. For example, if the data check unit 13 is set to acquire meter reading data every 30 minutes, the “meter reading date” of the meter reading data acquired this time and the “meter reading date” of the previously acquired meter reading data When there is an interval exceeding 30 minutes, it is determined that missing meter reading data has occurred. The determination result is sent to the retransmission request unit 14.

  The meter reading data may include serial number data issued at every meter reading timing. In this case, the data confirmation unit 13 can confirm the lack of meter reading data based on the continuity of the serial number data. That is, when the serial number of the meter reading data acquired this time is N, it can be determined that data loss has occurred when the serial number of the previously acquired data is not N-1.

  The retransmission request unit 14 generates a communication signal (retransmission request signal) for requesting data retransmission to the specific terminal station when the data confirmation unit 13 confirms that the meter reading data is missing from the specific terminal station. To do. For example, regarding the meter reading data of terminal station A every 30 minutes, if the meter reading data received this time is 17:00 data and the data stored as the previous data is meter reading data at 15:00, the retransmission request unit 14 Generates a retransmission request signal for requesting the terminal station A to transmit backup data of meter reading data of 15:30, 16:00, 16:30, which is missing data.

  The data storage part 15 memorize | stores the meter-reading data periodically transmitted from each terminal station A, B, C ... and received by the transmission / reception part 11. FIG.

  The transmitting / receiving unit 21 of the terminal station A is a functional unit for performing wireless data communication with the upper gateway GW or the lower terminals B and C. The transmitting / receiving unit 21 transmits the meter reading data of the watt-hour meter 24 and its own meter reading data periodically transmitted from the terminal stations B, C... To the collection server SV at every predetermined transmission timing. On the other hand, control data transmitted from the collection server SV is received.

  The control unit 22 controls each unit of the terminal station A, periodically reads the meter reading data of the watt-hour meter 24, and opens and closes the switch 25 based on the opening / closing control data transmitted from the collection server SV. In addition, when the retransmission request signal is given, the process of reading the corresponding backup data from the backup memory 23 and resending it to the collection server SV is controlled.

  The backup memory 23 is a memory that records meter reading data read from the watt-hour meter 24 for backup. In order to prevent the memory from being over, the control unit 22 may be provided with a routine for automatically erasing the data in the backup memory 23 when a predetermined period (for example, one month) has elapsed since the meter reading time.

  FIG. 5 is a time chart showing a state in which meter-reading data is periodically transmitted from a certain terminal station and is normally received by the gateway GW and the collection server SV through the upper-layer terminal station. Here, meter reading data D1, D2, D3, D4, D5, D6 every 30 minutes at predetermined transmission timings t1, t2, t3, t4, t5, t6 from the terminal station (for example, 15:00, 15: 30, 16:00, 16:30, 17:00, 17:30) is transmitted, and these are received by the collection server SV. In this embodiment, in order to suppress communication traffic as much as possible, an ACK from the collection server SV side to the terminal stations A, B, C... Is not transmitted.

  In such a case, when receiving the meter reading data D2, the data confirmation unit 13 compares the time data of the meter reading data D2 with the time data of the meter reading data D1 which is the previous received data. Thereafter, similarly, the time data of meter reading data D3 and D2, meter reading data D4 and D3, meter reading data D5 and D4, meter reading data D6 and D5 are compared. In this case, since all the meter reading data D1 to D6 at the transmission timings t1 to t6 have been received, the data confirmation unit 13 determines that there is no missing data.

  FIG. 6 is a time chart showing a state in which some meter reading data is not received by the collection server SV due to a temporary communication failure. Here, after the 30-minute meter reading data D11 is transmitted from the terminal station at the transmission timing t11 and received by the collection server SV, the meter reading data D12 to D14 at the following transmission timings t12, t13, t14 are transmitted from the terminal station This shows a case where the collection server SV is not received due to a temporary communication failure despite being transmitted.

  In this case, the terminal station cannot recognize that the meter reading data D12 to D14 have not arrived at the collection server SV. Therefore, the data reception status of all terminal stations is periodically checked at a predetermined cycle (for example, every 30 minutes) on the collection server SV side, and a data transmission request is transmitted to the terminal stations that have not yet received data. Is also possible. However, when this method is executed, the processing load on the collection server SV increases and communication traffic increases. If the communication failure continues in the first place, the data transmission request does not reach the terminal station, and unnecessary data transmission is performed. Therefore, in this embodiment, such a confirmation method is not adopted.

  In the present embodiment, the communication failure is recovered, and the 30-minute meter reading data D15 is transmitted at the transmission timing t15, and when this is received by the collection server SV, the lack of data is determined. That is, when the data checking unit 13 receives the meter reading data D15, the data checking unit 13 compares the time data of the meter reading data D15 with the time data of the meter reading data D11 as the previous received data. If the meter reading data D11 to D15 are meter reading data every 30 minutes, there will be a 2-hour interval between the time data of the meter reading data D11 and D15, so the data confirmation unit 13 reads the meter reading from the comparison result. The lack of data D12 to D14 is detected.

  In response to this, the retransmission request unit 14 generates a retransmission request signal for requesting transmission of backup data of the meter reading data D12 to D14 to the terminal station. This retransmission request signal is transmitted toward the terminal station, and in response thereto, backup data of meter reading data D12 to D14 is transmitted toward the collection server SV. Thereafter, when the transmission timing t16 arrives, the 30-minute meter reading data D16 is transmitted as usual. According to this method, since the meter reading data D15 is received and the retransmission request signal is transmitted only to a specific terminal station on the assumption that the communication path is secured, communication traffic is minimized. Can be suppressed.

  The operations of the collection server SV and the terminal stations A, B, C... Described above will be described with reference to FIGS. FIG. 7 is a flowchart showing the operation of meter reading data arrival confirmation processing in the collection server SV. Here, the processing flow for a certain terminal station is shown.

  When the transmission / reception unit 11 of the collection server SV receives certain meter reading data Da (step S1), the control unit 12 refers to the meter ID included in the meter reading data Da to determine the terminal station (hereinafter referred to as the terminal station A). The meter reading data Da is stored in the data storage unit 15 in association with the management number assigned to the terminal station A (step S2).

  Next, the control part 12 collates the data storage part 15, and determines whether the last meter-reading data Dn exists about the terminal station A (step S3). If the previous meter reading data Dn does not exist (NO in step S3), the control unit 12 sets the meter reading data Da received this time to “Dn” (step S4) and waits for the arrival of the next meter reading data in the terminal station A. .

  On the other hand, when the previous meter reading data Dn exists for the terminal station A (YES in step S3), the data confirmation unit 13 compares the time data of the current meter reading data Da with the time data of the previous meter reading data Dn ( In step S5), the continuity between meter reading data Dn and meter reading data Da is determined (step S6). For example, if the meter reading data is meter reading data every 30 minutes and the previous meter reading data Dn is as of 15:00 and the current meter reading data Da is as of 15:30 on the same day, the data confirmation unit 13 Is determined to be continuous (YES in step S6), the 15:30 meter reading data Da is set to "Dn" (step S4), and the terminal A waits for the next meter reading data to arrive.

  On the other hand, when there is no continuity as described above (NO in step S6), the data confirmation unit 13 is missing for the terminal station A based on the two compared time data and a predetermined meter reading cycle. Then, the meter reading data is specified. As illustrated in FIG. 6, the meter reading data is meter reading data every 30 minutes, the previous meter reading data Dn (D11) is at 15:00, and the current meter reading data Da (D15) is 17: If it is at the time of 00, the meter reading data D12 to D14 that should have been received in the meantime are specified as the missing meter reading data Dx (step S7).

  Based on this identification result, the retransmission request unit 14 generates a retransmission request signal for requesting retransmission of the missing meter reading data Dx to the terminal station A (step S8). This retransmission request signal is transmitted from the transmission / reception unit 11 to the terminal station A (step S9). Thereafter, the meter reading data Da at 17:00 is set to “Dn” (step S4), and the arrival of the next meter reading data at the terminal station A is awaited.

  FIG. 8 is a flowchart showing the operation of each of the terminal stations A, B, C. The control unit 22 determines whether or not the sampling period has arrived (step S11). When the sampling period has arrived (YES in step S11), the meter reading data is acquired from the watt-hour meter 24 (step S12). Data is stored in the backup memory 23 (step S13). If the sampling period has not arrived (YES in step S11), these steps S12 and S13 are skipped.

  Next, the control part 22 determines whether the transmission timing of the meter-reading data to the collection server SV has come (step S14). If it is the transmission timing (YES in step S14), the control unit 22 causes the transmission / reception unit 21 to transmit the meter reading data (step S15). On the other hand, when the transmission timing has not arrived (NO in step S14), step S15 is skipped.

  After transmitting meter-reading data, the control part 22 confirms whether the resending request signal transmitted from the collection server SV side was received in the transmission / reception part 21 within predetermined time (step S16). When the retransmission request signal is received, the control unit 22 reads the meter reading data Dx designated by the retransmission request signal from the backup memory 23 (Step S17), and retransmits the meter reading data Dx toward the collection server SV (Step S17). S18). Then, it returns to step S11 and a process is repeated. If no retransmission request signal is received, steps S17 and S18 are skipped.

  According to the wireless communication system according to the present embodiment described above, the processing load on the collection server SV is reduced, and communication traffic between the collection server SV and the terminal stations A, B, C,. be able to. Therefore, the meter reading data of each terminal station A, B, C... Can be reliably collected by the collection server SV.

  As mentioned above, although embodiment was described about this invention, this invention is not limited to this, For example, the deformation | transformation embodiment as shown below can be taken.

[1] In the above embodiment, an example in which the aggregation device includes the collection server SV and the gateway GW has been described. This is an example of an aggregation device, and may be an aggregation device including a plurality of servers, an aggregation device that does not use the gateway GW, and the like. Further, although the PHS method is exemplified as the wireless communication method between the terminal stations, other wireless communication methods can be adopted. For example, the present invention can be applied to a server and a client configuring a wireless LAN. Furthermore, a wired communication method may be employed instead of the wireless communication method.

[2] In the above embodiment, the meter reading data of the electric energy is exemplified as the collected data. The present invention can be applied to various types of data collection, and can be applied not only to collection of meter reading data of water meters and gas meters, but also to collection of various sensing data such as weather data, environmental data, and industrial measurement data.

[3] In the above embodiment, an example is shown in which the terminal stations A, B, C... Are network-connected in a tree shape having a plurality of hierarchies. Instead, each terminal station A, B, C... May be individually connected to the collection server SV.

[4] In the example shown in FIG. 6, in response to the backup data request from the collection server SV side, from the terminal station side, a timing separate from the regular transmission timings t11 to t16 (between t15 and t16). ) Showed an example of sending backup data. In order to further suppress communication traffic, backup data may be transmitted at the transmission timing t16 together with the meter reading data to be transmitted at the timing.

[5] In the above embodiment, even if data is lost over a long period of time, a backup meter reading data request is not transmitted unless meter reading data is transmitted. Even in such a case, it is considered that the failure of the communication path between the collection server SV and the terminal station continues, so it is appropriate not to transmit the backup meter reading data request signal. In such a case, for example, it is desirable that the meter reading data is received from the terminal station at a handy terminal or the like equipped with a communication means such as PHS over the site. In addition, in order to detect a terminal station in which meter-reading data is missing over a long period of time, it is necessary to check the meter-reading data of each terminal station stored in the collection server SV. What is necessary is just to be shorter than the period which memorize | stores meter-reading data.

It is a schematic diagram which shows the whole structure of the radio | wireless communications system which concerns on embodiment of this invention. It is a time chart which shows the transmission / reception state of data between a collection server and a terminal station. It is a block diagram which shows the function structure of a collection server and one terminal station. It is a data block diagram of the meter-reading data transmitted from a terminal station. It is a time chart which shows the state in which the meter-reading data transmitted regularly from the terminal station are received normally by the collection server. It is a time chart which shows the state in which some meter-reading data were not received by the collection server by temporary communication failure. It is a flowchart which shows operation | movement of the meter-reading data arrival confirmation process in a collection server. It is a flowchart which shows operation | movement of a terminal station.

SV collection server (aggregation device)
GW gateway (aggregation device)
A, B, C... Terminal station 11 Transmission / reception unit 12 Control unit 13 Data confirmation unit 14 Retransmission request unit 15 Data storage unit 21 Transmission / reception unit 22 Control unit 23 Backup memory 24 Energy meter 25 Switch

Claims (3)

An aggregation device that collects data acquired at each time of a predetermined cycle ;
A plurality of terminal stations that are connected to the aggregation device so as to be capable of wireless communication , and periodically transmit the data and time data that is the acquisition time of the data to the aggregation device;
The aggregation device is
A data confirmation unit for confirming the regular arrival status of the data from each terminal station upon receipt of the data, and time data associated with the data received this time and time data associated with the data received last time By comparing the interval between and the period, a data confirmation unit that detects the lack of data acquired at each time and the missing time ,
A retransmission request unit that generates a communication signal for requesting the specific terminal station to retransmit the data corresponding to the missing time when the data confirmation unit confirms that the data is missing from the specific terminal station. When,
A wireless communication system comprising: The wireless communication system according to claim 1 , wherein the terminal stations are network-connected in a tree shape having a plurality of hierarchies. Each terminal is capable of acquiring meter reading data from the metering device for the amount of power.
The wireless communication system according to claim 1 , wherein the data transmitted from each terminal station to the aggregation device is meter-reading data acquired at each terminal station.

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