JP4533163B2 - master station - Google Patents

Description

  The present invention relates to a communication system in which a small amount of information frequent communication and a large amount of information small frequency communication coexist, and a master station and a slave station constituting the communication system.

In general, communication by a polling control method is performed.
In addition, in communications where the amount of information is small and almost constant but requires frequent exchanges, the number of transmissions from the master station is reduced and communication efficiency is increased by performing simultaneous polling calls ( For example, Patent Document 3).

However, when communication as described above is mixed with communication that is infrequent but has a large amount of information and the amount of information is not constant, the communication channel usage efficiency is allocated because two different communication channels are allocated. Was getting worse.
For example, in a taxi dispatch management system, the position information and meter switching information of a taxi by GPS (Global Positioning System) is small and almost constant, but since it always requires the latest information, it is frequently exchanged. is required. On the other hand, a dispatch instruction and a response to the dispatch instruction are small in frequency, but the amount of information is large and the amount is not constant.
In such a situation, there are the following techniques for improving the use efficiency of the communication channel.

  There is a method (for example, Patent Document 1) that switches between a polling control method and a contention method in one communication channel according to a request from a slave station. However, this method requires a procedure for switching between the two methods, and a time delay occurs due to the overhead of switching the communication method.

  There is also a method (for example, Patent Document 2) in which a plurality of communication channels are used and the remaining communication channels are assigned to the polling control method and the contention method according to an instruction from the common control channel. However, this method requires a procedure for switching the channel for each requested communication, and a time delay occurs due to the overhead of switching the communication channel.

Alternatively, there is a method (for example, Patent Document 4) in which the uplink communication channel and the downlink communication channel are separated and both the polling call and the individual communication are performed on the downlink communication channel.
JP 61-171256 (pages 326-329) JP-A-9-205671 (Items 11-14, FIG. 5) Japanese Patent Laid-Open No. 10-234081 (Items 18 to 44, FIG. 5) JP 2004-146980 A (No. 28-46, FIGS. 1-4)

As described above, in communication in which a small amount of information and a high frequency are mixed and a communication in which a large amount of information and a low frequency are mixed, there is a problem of how to increase the use efficiency of the communication channel.
An object of the present invention is to solve the above-described problems, for example, and to build a communication system capable of high-speed communication of communication channels and high-speed information transmission with little time delay.

The slave station according to the present invention is
In a slave station that communicates with an uplink communication channel and a downlink communication channel,
A periodic information transmission command determination unit for determining that the signal received by the slave station reception unit is a periodic information transmission command for requesting transmission of periodic information;
When it is determined that the periodic information transmission command determination unit has received the periodic information transmission command, the slave station time measurement unit that measures the current time starting from the time when the periodic information transmission command is received;
A slave station transmitter for transmitting information to the uplink communication channel,
When the time measured by the slave station time measurement unit enters an arbitrary transmission time zone that allows the slave station to perform transmission, information other than the periodic information is transmitted,
When the time measured by the slave station time measurement unit does not enter the arbitrary transmission time zone, but when entering the regular information transmission time zone determined for each slave station so that transmissions from the slave stations do not overlap each other, Send the above periodic information,
When the time measured by the slave station time measurement unit does not fall within the arbitrary transmission time zone or the regular information transmission time zone, the slave station transmission unit that does not transmit,
It is characterized by having.

  The present invention, for example, can reduce communication channel switching time and communication procedure in a slave station that performs communication in which small amount of information frequent communication and large amount of information small frequency communication coexist. Is obtained. In addition, it is possible to perform communication individually without affecting the regular information collection cycle.

Embodiment 1 FIG.
The first embodiment will be described with reference to FIGS.

FIG. 1 shows the configuration of the entire communication system.
Base station 1 (an example of a master station) and taxi 2a to 2e (an example of a slave station) communicate by radio.
In this embodiment, the case where the number of taxis is five will be described as an example, but it goes without saying that other numbers may be used.
In this embodiment, a case where the slave station is a taxi will be described as an example. However, the slave station may be a mobile station such as a mobile phone or a fixed station.
Furthermore, in this embodiment, a case where communication is performed wirelessly will be described as an example. However, wired communication may be used.

For communication from the base station 1 to the taxis 2a to 2e, a radio channel 41 (an example of a downlink communication channel) using a carrier wave with the frequency F1 is used.
Since all taxis receive signals from the same wireless channel 41, all taxis can receive transmissions from the base station 1 simultaneously.
For communication from the taxis 2a to 2e to the base station 1, a radio channel 43 (an example of an uplink communication channel) using a carrier wave having a frequency F3 is used.
Since all taxis transmit signals to the same radio channel 43, the base station 1 cannot receive normally when transmissions from the taxis overlap.
Further, since the radio channel 41 and the radio channel 43 have different carrier frequencies, normal communication can be performed without interference even if two-way communication is performed in parallel. In this embodiment, the frequency division method is used to prevent interference, but other division methods such as a time division method may be used.

In this embodiment, there are roughly two types of information exchanged between the base station 1 and the taxis 2a to 2e.
The base station 1 needs to grasp the current positions of the taxis 2a to 2e and the state of empty cars and rents in order to perform appropriate vehicle allocation management. Therefore, information about the state is periodically collected from the taxis 2a to 2e.
This information is transmitted from the taxis 2a to 2e toward the base station 1, and is transmitted frequently although the amount of information is not large. This is because the base station 1 always grasps the latest state and performs efficient dispatch management.
In this way, information transmitted from all the slave stations to the master station and having a small amount of information but a high communication frequency is referred to as periodic information.

Communication between the base station 1 and the taxis 2a to 2e also includes information such as when the base station 1 instructs the specific taxi to dispatch vehicles individually and informs the base station 1 of the accident caused by the taxi. Exchanged.
This information is transmitted bidirectionally, and the frequency of communication is less than that of the regular information, but the communication time and the amount of information are indefinite.
As described above, information transmitted from the master station to the slave station is called individual information and information transmitted from the slave station to the master station is temporary information. I will call it.

FIG. 2 shows an internal configuration of the base station 1 (an example of a master station).
FIG. 3 shows the internal configuration of the taxi 2a (an example of a slave station). In addition, taxi 2b-2e is also the same structure.

The master station transmission unit 11 includes a modulator 111 and an antenna 112. Since the modulator 111 has already been adjusted by setting the carrier frequency to F1, the signal to be transmitted can be immediately transmitted to the radio channel 41.
The slave station receiving unit 22 includes a demodulator 221 and an antenna 222. Since the demodulator 221 has been adjusted by setting the frequency of the carrier wave to F1, the signal from the radio channel 41 can be received at any time.
Thereby, all the taxis 2a-2e receive the signal transmitted from the base station 1.

The slave station transmission unit 21 includes a modulator 211 and an antenna 212. Since the modulator 211 has been adjusted by setting the frequency of the carrier wave to F3, the signal to be transmitted can be immediately transmitted to the radio channel 43.
The master station receiving unit 12 includes a demodulator 121 and an antenna 122. Since the demodulator 121 has been adjusted by setting the frequency of the carrier wave to F3, the signal from the radio channel 43 can be received at any time.
Thereby, the base station 1 receives the signal transmitted from the taxi 2a. However, when the other taxis 2b to 2e transmit signals simultaneously, interference occurs and the base station 1 cannot receive the signals normally.

  Therefore, in this embodiment, the following configuration prevents duplication of transmission.

FIG. 4 shows the timing of communication. The horizontal axis is the time axis. FIG. 5 shows a frame structure that conceptually captures the timing of this communication. Similarly, the horizontal axis is the time axis.
The periodic information transmission command generation unit 141 periodically generates a periodic information transmission command based on a signal from the timer 131 and transmits the periodic information transmission command from the master station transmission unit 11.
As a result, the base station 1 periodically transmits a periodic information transmission command to the taxis 2a to 2e.
The taxis 2a to 2e receive the regular information transmission command at the slave station reception unit 22. When the decoding unit 251 decodes the signal and the periodic information transmission command determination unit 252 determines that it is a periodic information transmission command, the counter 232 is reset. The value of the counter 232 is incremented by 1 due to a periodic signal from the timer 231, and therefore indicates the current time starting from the time when the periodic information transmission command is received.
In this embodiment, the slave station time measurement unit 23 includes the counter 232 and the timer 231. However, this is merely an example, and other configurations may be used.

In the base station 1, when the periodic information transmission command generation unit 141 generates the periodic information transmission command 411, the counter 132 is reset. Since the value of the counter 132 is incremented by 1 due to a periodic signal from the timer 131, it indicates the current time starting from when the periodic information transmission command is generated. In this embodiment, the time delay from generation of the periodic information transmission command to transmission is so small that it can be ignored. Therefore, the value of the counter 132 is the current time starting from when the periodic information transmission command is transmitted as it is. It is treated as indicating. When this delay time cannot be ignored, a subtracter is further provided, and the current time starting from the time when the periodic information transmission command is transmitted is obtained by subtracting the value corresponding to the delay time from the value of the counter 132. It is good also as a structure. It is also conceivable to eliminate the influence of the delay time by adopting a configuration in which the counter is reset by a signal from the master station transmission unit.
In any case, what is listed here is merely an example of the master station time measurement unit 13 and may be realized by other configurations.

In this embodiment, since the base station 1 and the taxis 2a to 2e communicate directly by radio, the time taken from transmission to reception of the regular information transmission command 411 is so small that it can be ignored. Therefore, the time measured by the master station time measurement unit 13 and the time measured by the slave station time measurement unit 23 coincide with each other, and the base station 1 and the taxis 2a to 2e can perform synchronized operations.
Even if communication is performed using another communication method, the configuration may be left as it is as long as the delay time in communication is negligible, and when a delay occurs in communication (for example, a relay station intervenes and receives) If the delay time is constant even if the signal is temporarily accumulated and transmitted), the master station and slave stations can be synchronized by adopting a configuration that compensates for that delay. Is possible.

  In the taxi 2a, the control unit 27 stores the latest information from the GPS receiver 281 and the charge meter 282 in advance in the control unit 27 as information to be transmitted as regular information.

Each taxi has a different periodical information transmission time zone. The regular information transmission time zone is a time zone during which the taxi is allowed to transmit regular information. Since the taxis 2a to 2e do not transmit the regular information except for the regular information transmission time zone set in the taxi, the regular information transmission from the taxi does not overlap.
The regular information transmission time zone may be determined in advance as a fixed one or may be dynamically changed according to the situation. For example, when the number of taxis to be managed decreases, the total time it takes for all taxis to send regular information will be shortened as a whole by reducing idle time, and the collection of regular information accordingly This is preferable because the information update is quicker.
In that case, the control unit 17 of the base station 1 may determine the situation and allocate the regular information transmission time zone, or set the regular information transmission time zone based on the data input by the administrator from the terminal 19. You may make it the structure to carry out. When the periodic information transmission time zone is changed, this is notified to the taxis 2a to 2e as individual information.

  The regular information transmission time zone storage unit 162 of the base station 1 stores a regular information transmission time zone set for each taxi. FIG. 6 is an example of the contents stored in each storage unit (153, 162) of the base station 1. In this example, the periodical information transmission time zone storage unit 162 stores only the start time of the periodical information transmission time zone because the length of the periodical information transmission time zone is constant (in this example, 10 milliseconds). This is because it has been established. The reason why a plurality of regular information transmission time zones are set for each taxi is that the target of the regular information transmission command may be limited to some groups. This will be described later. The following description is for the case where the regular information transmission command targets all taxis (all targets).

  The regular information transmission time zone storage unit 261 of the taxis 2a to 2e also stores the same regular information transmission time zone as the regular information transmission time zone storage unit 162 of the base station 1. However, the regular information transmission time zone set for other vehicles may not be stored. This is because it is enough to know when the vehicle should transmit.

The periodic information signal generation unit 241 controls the current time measured by the slave station time measurement unit 23 when the current time measured by the slave station time measurement unit 23 matches the start time of the periodic information transmission time zone stored in the periodic information transmission time zone storage unit 261. A signal including the periodic information collected by the unit 27 is generated and transmitted from the slave station transmission unit 21.
Here, when the start time of the periodic information transmission time zone has passed, the configuration that does not generate a signal is that the length of the periodic information transmission time zone is such that the time required for transmission of the regular information just fits. This is because it takes only a length. If there is a margin in the length of the regular information transmission time zone, the signal may be generated after the start time has passed. However, the total period of time required for all taxis to transmit regular information is shorter as a whole if the length of the regular information transmission time period is set so that the time required for regular information transmission is just within the limit. Therefore, the period of periodic information collection can be shortened accordingly, which is preferable because information updating is accelerated.

In this example, since the start time of the regular information transmission time zone set for taxi 2a (car 11) is 10, taxi 2a transmits regular information 431a 10 milliseconds after receiving regular information transmission command 411a. Start and end transmission within 10 milliseconds. If this is conceptually understood, the regular information from the taxi 2a is transmitted using the slot 2 (302a) of the frame 30a.
Since the start time of the regular information transmission time zone set for taxi 2b (car 12) is 20, taxi 2b starts transmitting regular information 431b 20 milliseconds after receiving regular information transmission command 411a. End transmission within milliseconds. That is, the regular information from the taxi 2b is transmitted using the slot 3 (303a) of the frame 30a.
Since the start time of the regular information transmission time zone set for the taxi 2c (No. 13 car) is 30, the taxi 2c starts transmitting the regular information 431c 30 milliseconds after receiving the regular information transmission command 411a. End transmission within milliseconds. That is, the regular information from the taxi 2 is transmitted using the slot 4 (304a) of the frame 30a.
Since the start time of the regular information transmission time zone set for the taxi 2d (No. 21 car) is 50, the taxi 2d starts transmitting the regular information 431d 50 milliseconds after receiving the regular information transmission command 411a. End transmission within milliseconds. That is, the regular information from the taxi 2d is transmitted using the slot 6 (306a) of the frame 30a.
Since the start time of the regular information transmission time zone set for taxi 2e (No. 22 car) is 60, taxi 2e starts transmitting regular information 431e 60 milliseconds after receiving regular information transmission command 411a. End transmission within milliseconds. That is, the regular information from the taxi 2e is transmitted using the slot 7 (307a) of the frame 30a.

  In this way, if a different periodic information transmission time zone is defined for each slave station, there is no duplication of regular information transmission from the slave stations, so the master station receives regular information from all the slave stations. It can be received correctly.

  In the base station 1, the control unit 17 sends the periodic information received in this way to the data storage unit 18, and the data storage unit 18 stores this data. The terminal 19 can refer to the information about the specific taxi in the data storage unit 18, thereby grasping the current position and the renting state of the taxi and referring to the past history.

In this embodiment, there is only one terminal, but there may be a plurality of terminals.
Furthermore, the terminal does not need to be inside the base station, but may be configured to be connected to the base station via a communication line or the like.

The base station 1 can always store the latest information in the data storage unit 18 by periodically generating and transmitting a periodic information transmission command.
In this procedure, since there is no switching of communication channels, data can be collected at high speed.

  Next, the case where it becomes necessary to transmit temporary information to the base station 1 in the taxis 2a to 2e will be described.

The regular information transmission time zone is set so that a free time zone occurs in some places. During this time, all taxis may send temporary information. This time zone is referred to as an arbitrary transmission time zone.
By using this time zone when a taxi wants to send a signal of sudden urgency at a timing other than the regular information transmission, the taxi information can be updated at an interval shorter than the periodic information collection cycle.

The arbitrary transmission time zone is stored in the arbitrary transmission time zone storage unit 153 of the base station 1 and the arbitrary transmission time zone storage unit 262 of the taxis 2a to 2e. FIG. 6 shows an example of the contents stored in the arbitrary transmission time zone storage unit 153 of the base station 1, but the same contents are also stored in the arbitrary transmission time zone storage units 262 of the taxis 2a to 2e. Yes.
Since the arbitrary transmission time zone is integrated with the regular information transmission time zone, when the periodic information transmission time zone changes dynamically, the arbitrary transmission time zone also changes. In that case, this is notified to the taxis 2a to 2e as individual information.
In this example, 40 ms to 50 ms after receiving the periodic information transmission command 411a (slot 5 (305a)), and 70 ms to 80 ms (slot 8 (308a)) are arbitrarily transmitted. It is a time zone.

  FIG. 7 is an example of an uplink communication signal format generated by the regular information signal generation unit 241 and the temporary information signal generation unit 242 of the taxis 2 a to 2 e and transmitted from the slave station transmission unit 21.

For example, it is assumed that an emergency occurs in taxi 2c (# 13 car). The driver presses the emergency call button 283. The control unit 27 detects this and notifies the temporary information signal generation unit 242.
The temporary information signal generation unit 242 receives this, and waits for the current time measured by the slave station time measurement unit 23 to coincide with the start time of the arbitrary transmission time zone stored in the arbitrary transmission time zone storage unit 262. If they match, a signal including temporary information is generated and transmitted from the slave station transmitter 21.
In this example, the temporary information signal generation unit 242 of the taxi 2c (No. 13 car) generates a signal including the temporary information in the identifier 61 as “01”, the car number 62 as “00000001101”, and the data 65 as a periodic information transmission command. It was transmitted 70 milliseconds after the reception of 411a (slot 8 (308a)).

  This signal is received by the base station receiver 12 of the base station 1 and decoded by the decoding unit 151. The transmitting station information identifying unit 152 identifies the taxi that transmitted the signal from the car number 62. In this case, since the car number 62 is “00000001101”, the transmitting station information identifying unit 152 identifies that this signal is from the 13th car and informs the control unit 17.

In this embodiment, the same signal format is adopted for the periodic information signal, and the vehicle number is notified to the base station 1.
However, in the regular information transmission time zone, only one taxi is permitted to transmit at that time, so the time when the regular transmission station identification unit 161 received the signal and the regular information transmission time zone storage unit 162 are stored. By comparing the regular information transmission time zones, the taxi that transmitted the signal can be identified.
Therefore, it is conceivable to adopt a signal format that does not include the car number 62 in the periodic information signal.
Or conversely, it is possible to identify the taxi that transmitted the signal based on the car number 62 included in the regular information signal, and not take the signal reception time into consideration.
However, as in this embodiment, when the taxi transmitted from both sides is specified, when some trouble occurs and the two information contradicts, the control unit 17 recognizes that and is necessary. It is preferable because measures can be taken.

  Since the information amount of the temporary information is indefinite, the communication is not always finished within the length of one arbitrary transmission time slot (in this example, 10 milliseconds). In that case, the information is divided into several parts and transmitted in a plurality of arbitrary transmission time zones. (In some cases, it may be over an arbitrary transmission time period for the next periodic information transmission command.)

  A combination of a regular information transmission time zone set for each taxi and an arbitrary transmission time zone common to all taxis is a response to one regular information transmission command as a whole. This is combined with the slot that transmitted the periodic information transmission command to form one frame. In this example, the transmission of the periodic information transmission command 411a is 1 slot, the periodic information transmission time zone of each taxi is 5 slots for 1 slot at a time, and the arbitrary transmission time zone is 2 slots. Yes. In this example, since the length of one slot is 10 milliseconds, one frame is obtained in 80 milliseconds.

  Therefore, if the base station 1 transmits the periodic information transmission command 411 with an interval of 80 milliseconds or more, it is possible not only to always collect the latest information from the taxis 2a to 2e, but also to be sudden and highly urgent. If a situation occurs in a taxi, taxi information can be updated at shorter intervals.

Since a plurality of taxis may transmit temporary information during an arbitrary transmission time zone, there is a possibility that transmission of temporary information may overlap. However, since the temporary information has a lower frequency of communication than the regular information, the possibility of duplicate transmission is small. Therefore, in most cases, the base station 1 can correctly receive the temporary information from the taxis 2a to 2e.
In this example, there are two arbitrary transmission time zones, but of course other than two may be used. If the number of arbitrary transmission time zones is large, the possibility of overlapping transmissions is reduced accordingly. However, if the number of arbitrary transmission time zones is increased, the length of one frame becomes longer, and the period of periodic information collection becomes longer accordingly, so that information update is delayed. It is necessary to select the optimum number in consideration of the necessary information update cycle, the frequency with which the temporary information needs to be transmitted, and the amount of information.

  In this example, the temporary information is transmitted by selecting an arbitrary transmission time zone in which the temporary information can be transmitted earliest. However, if all the slave stations select the earliest arbitrary transmission time zone, there is a possibility that transmissions are likely to overlap. Therefore, when there are a plurality of arbitrary transmission time zones, it may be desirable to select a random transmission time zone in which transmission is performed at random to avoid duplication of transmission.

  In some cases, it may not be necessary to collect regular information from all taxis. In such a case, if a taxi that is not necessary does not transmit regular information, the length of one frame can be shortened accordingly, so the periodic information collection cycle is shortened and information is updated more quickly. ,preferable.

FIG. 8 shows an example of a downlink communication signal format generated by the regular information transmission command generation unit 141 and the individual information signal generation unit 142 of the base station 1 and transmitted from the master station transmission unit 11.
In this example, the periodic information transmission command generated by the periodic information transmission command generation unit 141 has the identifier 51 of “00” or “01”. This is received by the slave station receivers 22 of the taxis 2a to 2e, decoded by the decoding unit 251, and the periodic information transmission command determination unit 252 looks at the identifier 51 and determines that it is a periodic information transmission command.

  When the identifier 51 is “00”, the regular information transmission command is for all taxis, and the regular information signal generation unit 241 is stored in the regular information transmission time zone storage unit 261. In the table, the periodic information signal is generated according to the periodic information transmission time zone stored in the column for all objects.

When the identifier 51 is “01”, the periodic information transmission command is for a group. The target number 52 indicates the number of the target group.
Therefore, when the target number 52 is “0000000001”, since the group 1 is the target, the periodic information signal generation unit 241 includes the group 1 target in the table stored in the periodic information transmission time zone storage unit 261. The periodic information signal is generated according to the periodic information transmission time zone stored in the column. In this example, if the start time of the regular information transmission time zone is “0”, it means that the taxi does not belong to the group and therefore the regular information is not transmitted.

For example, a periodic information transmission command for group 1 will be described.
In the base station 1, the periodic information transmission command generation unit 141 generates the periodic information transmission command 411b having the identifier 51 of “01” and the target number 52 of “0000000001”, and the master station transmission unit 11 transmits the periodic information transmission command 411b.

This signal is received by all taxis 2a-2e.
The taxi 2a (No. 11 car) starts transmitting the periodic information 10 milliseconds after the reception of the periodic information transmission command 411b (slot 2 (302b)).
The taxi 2b (No. 12 car) starts transmitting the periodic information 20 milliseconds after the reception of the periodic information transmission command 411b (slot 3 (303b)).
The taxi 2c (No. 13 car) starts transmitting the periodic information 40 milliseconds after the reception of the periodic information transmission command 411b (slot 5 (305b)).
Taxi 2d (No. 21 car) and taxi 2e (No. 22 car) do not belong to group 1 and therefore do not transmit regular information this time.

In this case, since the arbitrary transmission time zone varies depending on the target of the periodic information transmission command, the temporary information signal generation unit 242 is also stored in the group 1 target column in the table stored in the arbitrary transmission time zone storage unit 262. A temporary information signal is generated according to an arbitrary transmission time zone.
In this example, the arbitrary transmission time zone for the group 1 target is 30 milliseconds to 40 milliseconds after the reception of the periodic information transmission command (slot 4 (304b) of the frame 30b), 50 milliseconds to 60 milliseconds later. After a second (slot 6 (306b) of frame 30b). Since an emergency occurred in taxi 2e, it was sent 30 milliseconds (slot 4 (304b)) after receiving the periodic information transmission command.

  In this case, the length of one frame is 60 milliseconds. Therefore, if the base station 1 transmits the regular information transmission command 411 with an interval of 60 milliseconds or more, the regular information from the necessary taxi can be collected.

  In this way, when it is not necessary to collect periodic information from all the slave stations, by limiting the slave stations that are subject to the periodic information transmission command, the periodic information collection cycle is shortened and the information is updated. It is preferable because it is faster.

  Next, a case where the base station 1 needs to transmit individual information to the taxis 2a to 2e will be described.

The radio channel 41 used for communication from the base station 1 to the taxis 2a to 2e is used only for transmission of the regular information transmission command 411 in normal times. Therefore, it can be used for transmission of individual information at other times.
During time periods other than the transmission of the regular information transmission command 411, the regular information and temporary information from the taxis 2a to 2e are almost always transmitted using the wireless channel 43. However, since the radio channel 41 and the radio channel 43 are configured not to interfere with each other, even if the base station 1 transmits the individual information using the radio channel 41, the taxis 2a to 2e can correctly receive the individual information. The base station 1 can also correctly receive regular information and temporary information from the taxis 2a to 2e.

  For example, it is assumed that a customer requests a pick-up by telephone. When customer information is input to the terminal 19 by the operator, the terminal 19 inquires the data storage unit 18 of the position information / rental status information of each taxi and finds out the taxi that can go to the customer the earliest. Here, it is assumed that the taxi 2d (No. 21 car) is in an empty state and is closest to the customer. The terminal 19 determines that the taxi 2d should be directed, sends a dispatch instruction for the taxi 2d and information on the current location of the customer to the control unit 17, and requests that this information be transmitted to the taxi 2d. The control unit 17 notifies the individual information signal generation unit 142 that this information and the transmission target are the taxi 2d. The individual information signal generation unit 142 determines the timing at which the periodic information transmission command generation unit 141 does not generate the periodic information transmission command based on the signal from the timer 131, and transmits the individual information 412 a from the master station transmission unit 11.

  According to FIG. 8, the signal generated by the individual information signal generation unit 142 has the identifier 51 of “10” or “11”. In the case of “10”, the group is targeted, and the target number 52 indicates the group number. In the case of “11”, one vehicle is targeted, and the target number 52 indicates the vehicle number.

  In this example, since taxi 2d (No. 21 car) is targeted, the individual information signal generation unit 142 generates an individual information signal having the identifier 51 of “11” and the target number 52 of “0000010101”, and the previous regular information It was transmitted 20 milliseconds after the transmission of the transmission command 411a.

This signal is received by all taxis 2a-2e. However, since the identifier 51 is neither “00” nor “01”, the periodic information transmission command determination unit 252 determines that this signal is not a periodic information transmission command. Therefore, the counter 232 is not reset.
On the other hand, the control unit 27 determines whether the signal is intended for itself. In this example, since the identifier 51 is “11” and the target number 52 is “0000010101”, the control units 27 of the taxis 2a to 2c and 2e determine that they are not the target and do nothing.
On the other hand, the control unit 27 of the taxi 2d determines that it is the subject and controls each unit so as to perform an operation according to the content of the information.

  In this example, the content of the individual information is information relating to a vehicle dispatch instruction and the current location of the customer. Therefore, the control unit 27 sends a vehicle dispatch instruction from the speaker 292 using synthesized speech, asks the driver, and sends information on the current position of the customer to the car navigation 291 to display the shortest route.

In this example, there is a lot of information to be transmitted, and it could not fit in one slot, so transmission is performed in two slots, slot 3 (303a) and slot 4 (304a). In this case, the division number 53 is “010”, the division number is “001” in the slot 3 (303a), and “010” in the slot 4 (304a).
Of course, it is also conceivable that the signal format does not include the number of divisions or division numbers. However, since the information amount of the individual information is not constant, the individual information may fit in one slot or may span a plurality of slots. It is preferable to include the number of divisions and the division number in the signal format because it is possible to determine whether all the information to be received by the slave station has been received.

  If the signal format shown in FIG. 8 is used, not only is it possible to send individual information to one taxi as in this example, but it is also possible to broadcast individual information to multiple taxis or all taxis. it can. In that case, the identifier 51 may be “10” and the target number 52 may be the group number. The taxi control unit 27 stores in advance which group the vehicle belongs to and which group the vehicle does not belong to, and determines whether the vehicle is the target.

  As a result, the transmission target can be freely selected from a single slave station, some slave stations, or all slave stations, and information of an arbitrary length can be transmitted.

With such a configuration, even when extraordinary information or individual information is transmitted, the length of one frame does not change, so that the periodic information collection cycle is kept constant and the update of information is not delayed.
In addition, since it is not necessary to switch the communication channel for each transmission of information, the time required for each communication can be shortened, and the periodic information collection cycle is shortened, so that the latest information can always be obtained. it can.
Furthermore, even if the number of channels used for communication is reduced, necessary communication can be ensured and efficiency is improved.

Embodiment 2. FIG.
The second embodiment will be described with reference to FIGS.

FIG. 9 shows the configuration of the entire communication system.
Base station 1 (an example of a master station) and taxi 2a to 2t (an example of a slave station) communicate by radio.
In this embodiment, the case where the number of taxis is 10 will be described as an example, but it goes without saying that other numbers may be used.
In this embodiment, a case where the slave station is a taxi will be described as an example. However, the slave station may be a mobile station such as a mobile phone or a fixed station.
Furthermore, in this embodiment, a case where communication is performed wirelessly will be described as an example. However, wired communication may be used.

For communication from the base station 1 to the taxis 2a to 2e, a radio channel 41 (an example of a downlink communication channel) using a carrier wave with the frequency F1 is used.
Since all taxis receive signals from the same wireless channel 41, all taxis can receive transmissions from the base station 1 simultaneously.

In this embodiment, unlike Embodiment 1, there are two radio channels (an example of an uplink communication channel) used for communication from taxis 2a to 2t (an example of a slave station) to base station 1 (an example of a master station). It is prepared.
For communication from the taxi 2a to 2e to the base station 1, a radio channel 43 using a carrier wave having a frequency F3 is used.
For communication from the taxi 2p to 2t to the base station 1, a radio channel 44 using a carrier wave with a frequency F4 is used.
In this way, all taxis are divided so as to belong to one of the two groups, and the radio channel used for transmission by each group is determined.
Since taxis in the same group transmit signals to the same radio channel, the base station 1 cannot receive normally when transmissions from taxis in the same group overlap.
Since the radio channel 43 and the radio channel 44 have different carrier frequencies, no interference occurs even if communication is performed in parallel. Since taxis in different groups transmit signals to different radio channels, the base station 1 can receive normally even if transmissions from taxis in different groups overlap.
Further, since the radio channel 41 has a carrier frequency different from that of both the radio channel 43 and the radio channel 44, even if two-way communication is performed in parallel, normal communication can be performed without interference. Therefore, in this embodiment, three communications can be performed in parallel.
In this embodiment, the frequency division method is used to prevent interference, but other division methods such as a time division method may be used.

FIG. 10 shows the internal configuration of the base station 1 (an example of a master station).
FIG. 11 shows an internal configuration of the taxi 2a (an example of a slave station). The taxis 2b to 2t have the same configuration.

In this embodiment, unlike the first embodiment, there are two master station receivers (12a, 12b).
Since the demodulator 121a of the master station receiving unit 12a has been adjusted by setting the frequency of the carrier wave to F3, the signal from the radio channel 43 can be received at any time.
Since the demodulator 121b of the master station receiving unit 12b has been adjusted by setting the frequency of the carrier wave to F4, the signal from the radio channel 44 can be received at any time.
Therefore, the base station 1 is configured to be able to receive the signal from the radio channel 43 and the signal from the radio channel 44 in parallel.

Since the modulators 211 of the taxis 2a to 2e have been adjusted by setting the frequency of the carrier wave to F3, a signal to be transmitted can be immediately transmitted to the radio channel 43.
Since the modulator 211 of the taxis 2p to 2t has been adjusted by setting the frequency of the carrier wave to F4, the signal to be transmitted can be immediately transmitted to the radio channel 44.

  FIG. 12 shows the timing of communication. The horizontal axis is the time axis. FIG. 13 shows a frame structure that conceptually captures the timing of this communication. Similarly, the horizontal axis is the time axis.

  In this embodiment, as in the first embodiment, by setting a different regular information transmission time zone for each taxi, duplication of regular information transmission is prevented. FIG. 14 is an example of the contents stored in each storage unit (163, 162, 153) of the base station 1. The same information as the regular information transmission time zone storage unit of the base station 1 is also stored in the regular information transmission time zone storage unit 261 of the taxi 2a to 2t. However, the periodic information transmission time zone for other vehicles may not be stored. This is because it is enough to know when the vehicle should transmit.

The same contents as the used channel storage unit of the base station 1 are also stored in the used channel storage unit 263 of the taxis 2a to 2t. However, the use channel for other vehicles may not be stored. This is because it is sufficient to know the channel that the vehicle should use.
Furthermore, if the communication channel used for transmission by the child station is fixed, the use channel storage unit may not be provided in the child station. However, it is possible to change the allocation of the used channel to the slave station according to the situation by providing a used channel storage unit and dynamically changing the channel to be used according to the instruction from the master station. Since efficiency can be improved, it is preferable.

The modulators 211 of the taxis 2a to 2t set the carrier frequency based on the radio channel stored in the used channel storage unit 263.
In this example, different periodic information transmission time zones are set for all taxis in a group that uses the same radio channel, but the same periodic information transmission time zone is set for groups that use different radio channels. Some are set.
For example, the taxi 2a that uses the wireless channel 43 and the taxi 2p that uses the wireless channel 44 transmit regular information using the same slot 302a.

  However, since the radio channel 43 and the radio channel 44 use carrier waves of different frequencies, there is no interference even if they are transmitted at the same time, and the base station 1 has a master station receiver (12a) corresponding to each radio channel. 12b), signals from both radio channels can be received normally.

  Furthermore, the base station 1 identifies the taxi that transmitted the information by comparing the wireless channel that received the periodic information and the time with the stored contents of the used channel storage unit 163 and the periodic information transmission time zone storage unit 162. It is also possible to do.

  This allows regular information from multiple taxis to be sent in the same slot, which reduces the number of slots required to collect regular information from all taxis as a whole. Minutes, the length of one frame is shortened.

  In this example, since the number of taxis allocated to each radio channel is five, the slot corresponding to the regular information transmission time zone may be five slots per frame. On the other hand, if only one uplink communication channel is used, the slot corresponding to the periodic information transmission time zone needs 10 slots per frame, so the length of one frame is shortened by 5 slots.

Therefore, even when the number of taxis is large, the length of one frame can be suppressed, so that the periodic information collection cycle is shortened and information is updated more quickly.
In this embodiment, the case where two uplink communication channels are used has been described. However, if this number is increased and the number of slave stations allocated to each uplink communication channel is reduced, the period of periodic information collection is further increased. Needless to say, it can be shortened.

  Also for the transmission of temporary information, as in the first embodiment, the time zone that does not overlap with the transmission of the periodic information is set as the arbitrary transmission time zone, thereby preventing the duplication with the transmission of the periodic information. FIG. 14 shows an example of an arbitrary transmission time zone stored in the arbitrary transmission time zone storage unit 153 of the base station 1. The arbitrary transmission time zone may differ depending on the radio channel as in this example. Therefore, the arbitrary transmission time zone storage unit 153 of the base station 1 stores an arbitrary transmission time zone for each radio channel. The same content as the arbitrary transmission time zone storage unit 153 of the base station 1 is also stored in the arbitrary transmission time zone storage unit 262 of the taxis 2a to 2t, but the wireless channel other than the radio channel used by the own vehicle is stored. The arbitrary transmission time zone may not be stored. This is because it is enough to know when the vehicle can transmit.

Since a plurality of taxis may transmit temporary information during an arbitrary transmission time zone, there is a possibility that transmission of temporary information may overlap. However, in this embodiment, the base station 1 can receive normally even if transmission overlaps between groups using different radio channels.
Therefore, even if the number of taxis is large and there is a high possibility that the transmission of temporary information is duplicated, the possibility that the base station 1 cannot receive normally due to the duplicate transmission of temporary information is not so high.

For example, it is assumed that the taxi 2a and the taxi 2q transmit temporary information at the same time.
However, since the taxi 2a uses the radio channel 43, the taxi 2q uses the radio channel 44, so the base station 1 can normally receive the temporary information from both.

  Thereby, even when there are many taxis, it is not necessary to increase the number of arbitrary transmission time zones so much.

  Therefore, even when the number of taxis is large, the length of one frame can be suppressed, so that the periodic information collection cycle is shortened and information is updated more quickly.

Embodiment 3 FIG.
The third embodiment will be described with reference to FIGS.

FIG. 15 shows the configuration of the entire communication system.
Base station 1 (an example of a master station) and taxi 2a to 2e (an example of a slave station) communicate by radio.
In this embodiment, the case where the number of taxis is five will be described as an example, but it goes without saying that other numbers may be used.
In this embodiment, a case where the slave station is a taxi will be described as an example. However, the slave station may be a mobile station such as a mobile phone or a fixed station.
Furthermore, in this embodiment, a case where communication is performed wirelessly will be described as an example. However, wired communication may be used.

For communication from the base station 1 to the taxis 2a to 2e, a radio channel 41 (an example of a downlink communication channel) using a carrier wave with the frequency F1 is used.
Since all taxis receive signals from the same wireless channel 41, all taxis can receive transmissions from the base station 1 simultaneously.
Separately from this, a radio channel 42 (an example of a downlink communication channel) using a carrier wave of frequency F2 is also used for communication from the base station 1 to the taxis 2a to 2e.
However, the taxi normally receives the radio channel 41 and is configured to switch the reception channel to the radio channel 42 only when instructed by the base station 1.
Therefore, the signal from the radio channel 42 can be received only by a taxi that has received an instruction from the base station 1.

In the first embodiment and the second embodiment, the individual information transmitted from the base station 1 to the taxi is transmitted using the radio channel 41 that can be received by all taxis.
However, this can be a problem. For example, in order to reduce the cost of installing a base station, when several taxi companies jointly use the same communication system, there may be cases where individual taxis do not want to receive individual information.
In addition, when the number of taxis is large, the amount of individual information transmitted from the base station 1 to the taxi also increases. In that case, there may be a case where one communication channel is not sufficient for transmitting the individual information.

FIG. 15 shows an internal configuration of the base station 1.
FIG. 16 shows the internal configuration of the taxi 2a. The taxis 2b to 2e have the same configuration.

The base station 1 has two master station transmitters (11a, 11b).
Since the modulator 111a of the master station transmitter 11a has been adjusted by setting the frequency of the carrier wave to F1, the signal to be transmitted can be immediately transmitted to the radio channel 41.
Since the modulator 111b of the master station transmitter 11b has already been adjusted by setting the frequency of the carrier wave to F2, the signal to be transmitted can be immediately transmitted to the radio channel 42.
Since the demodulator 221 of the slave station reception unit 22 has normally been adjusted by setting the frequency of the carrier wave to F1, the signal from the radio channel 41 can be received at any time.
Further, the demodulator 221 of the slave station receiver 22 can also receive a signal from the radio channel 42 by setting the frequency of the carrier wave to F2.

  FIG. 17 shows the timing of communication. The horizontal axis is the time axis. FIG. 18 shows a frame structure that conceptually captures the timing of this communication. Similarly, the horizontal axis is the time axis.

  For example, a case where the base station 1 needs to transmit individual information to the taxi 2d and the taxi 2e will be described. Here, it is assumed that the individual information is not desired to be received by the other taxis 2a to 2c.

  The control unit 17 instructs the channel switching command generation unit 143 to generate a channel switching command. The channel switching command generation unit 143 determines the timing at which the periodic information transmission command generation unit 141 does not generate the periodic information transmission command based on the signal from the timer 131, and transmits the channel switching command 413 from the master station transmission unit 11a. .

FIG. 19 shows the signal format of the downlink communication generated by the periodic information transmission command generation unit 141, the individual information signal generation unit 142, and the channel switching command generation unit 143 of the base station 1 and transmitted from the parent station transmission unit 11a or 11b. An example is shown.
In this example, taxis 2d and 2e belong to group 3, and no other taxi belongs to group 3.
According to this, since the target taxi is not a single taxi but a group, the identifier 51 is “10”.
Next, the target number 52 is the number “0000000011” of the group to which the taxis 2d and 2e belong.
The division number 53 is “000” because it is a channel switching command.

This signal is received by all taxis 2a-2e. However, since the identifier 51 is neither “00” nor “01”, the periodic information transmission command determination unit 252 determines that this signal is not a periodic information transmission command. Therefore, the counter 232 is not reset.
On the other hand, the control unit 27 determines whether the signal is intended for itself. In this example, since the identifier 51 is “10” and the target number 52 is “0000000011”, the control unit 27 of the taxi 2a to 2c that does not belong to the group 3 determines that it is not the target and does nothing.
On the other hand, the control units 27 of the taxis 2d and 2e belonging to the group 3 determine that they are the target and inform the channel switching command determination unit 253.

Since the signal identifier 51 is “10” and the division number 53 is “000”, the channel switching command determination unit 253 determines that this signal is a channel switching command. Further, the channel switching command determination unit 253 of the taxis 2d and 2e belonging to the group 3 instructs the demodulator 221 to switch the frequency of the carrier wave of the reception channel to F2, since this signal is intended for itself. .
The demodulator 221 of the taxis 2d and 2e switches the frequency of the carrier wave to F2 accordingly. Thereby, the taxis 2d and 2e can receive the signal of the radio channel 42 thereafter.

  The control unit 17 of the base station 1 notifies the individual information signal generation unit 142 of the individual information to be transmitted. After transmitting the channel switching command, the individual information signal generation unit 142 generates the individual information 422a after allowing the taxi to switch channels and prepare for reception, and generates the individual information 422a from the master station transmission unit 11b. Transmit using the radio channel 42.

  In this example, the transmission of the individual information 422a is started after an interval of 1 slot (10 milliseconds) from the transmission of the channel switching command 413a. However, it goes without saying that different intervals may be used depending on the time required for channel switching.

  Since the individual information in this example has a length of three slots, the individual information 422a generated by the individual information signal generation unit 142 has a division number 53 of “011” and division numbers of “001” and “010”, respectively. It is composed of three signals “011”.

Since the slave station receivers 22 of the taxis 2d and 2e are prepared to receive signals from the radio channel 42, they receive the individual information 422a. On the other hand, since the taxis 2a to 2c receive the signal from the radio channel 41, they cannot receive the individual information 422a.
When reception of the individual information 422a is completed, the individual communication end determination unit 254 determines reception completion.

For example, the number of signals to be received is determined from the division number 53 in the signal format of the individual information 422a.
In this example, since the division number 53 of the signal received first in the slot 5 is “011”, the individual communication end determination unit 254 determines that signals over a total of three slots should be received. Thereafter, after receiving signals for two slots, it is determined that the reception of the individual information 422a is completed.
Alternatively, if the signal received by the division number 54 is managed, it can be checked whether all the signals to be received have been received. For example, if the base station 1 transmits the same signal twice due to some trouble, if the division number 54 is “001”, “010”, “001”, respectively, the signal of the division number “011” is still You can see that it has not been received. If management by the division number is not performed, it is determined that reception has been completed because signals for three slots have been received.
Alternatively, a special signal indicating the end of transmission may be transmitted at the end of the individual information 422a transmitted from the base station 1, and it may be determined that the reception is completed when the signal is received.

When the individual communication end determination unit 254 determines the end of reception, it instructs the demodulator 221 to return the carrier frequency of the reception channel to F1.
The demodulator 221 of the taxis 2d and 2e switches the frequency of the carrier wave to F1 accordingly. As a result, the taxis 2d and 2e can no longer receive the signal of the radio channel 42. Therefore, even if another individual information is subsequently transmitted using the wireless channel 42, the other individual information cannot be received unless the taxi 2d or 2e is designated as the target.

  In this embodiment, there is only one slave station receiver, and the reception channel is switched. However, the slave station receiver that receives the radio channel 41 and the slave station receiver that receives the radio channel 42 are configured. The slave station receiver that receives the radio channel 42 may be turned on / off by a channel switching command. However, when the slave station is a mobile station, it is desired that the mobile station side apparatus be as small and light as possible. Therefore, a configuration in which one slave station receiving unit is switched and used is preferable.

  Next, the case where it becomes necessary to transmit the second individual information to the taxi 2b during the transmission of the individual information to the taxis 2d and 2e will be described. However, the second individual information may be received by another taxi.

  In the first embodiment or the second embodiment, when it is necessary to transmit a plurality of pieces of individual information to different taxis, it is necessary to wait for one transmission to finish and then transmit the other. A delay occurs until the transmission is completed. This is because there is only one downlink communication channel. Alternatively, it is conceivable that one transmission is interrupted and the other is transmitted, or one transmission and the other transmission are alternately performed. However, there is no great difference in that a delay occurs until all transmissions are completed.

  However, in this embodiment, since there are two downlink communication channels, if one of the downlink communication channels is in use and the other is free, individual information can be transmitted using that channel.

In this example, since it is necessary to transmit the second individual information while transmitting the individual information using the wireless channel 42, the second individual information is transmitted using the wireless channel 41. Since the transmission procedure is the same as that described in the first embodiment, it is omitted here.
On the other hand, when it is necessary to transmit the second individual information to a taxi different from the target while transmitting the individual information using the wireless channel 41, the individual information using the wireless channel 41 is changed. Transmission is interrupted, a channel switching command for the taxi that is the target of the second individual information is transmitted, and then transmission of the individual information is resumed. Thereafter, the second individual information is transmitted using the radio channel 42.

  In this example, the case where there are two downlink communication channels has been described as an example, but it goes without saying that there may be three or more. In this case, it is preferable to limit the downlink communication channel that can be switched for each slave station because the confidentiality of the individual information is increased. Moreover, the number of pieces of individual information that can be transmitted simultaneously increases, which is preferable. However, when the frequency at which the individual information needs to be transmitted is low, the use efficiency of the downlink communication channel is deteriorated, and therefore an appropriate number needs to be selected.

Thereby, it is possible to prevent the slave station other than the slave station targeted for the individual information from being received. Also, a plurality of individual information can be transmitted simultaneously to different slave stations.
Furthermore, since the slave station does not need to switch the channel to be received only when such a need arises, and does not need to switch the channel to be received in other cases, the delay caused by the adjustment accompanying the switching of the communication channel, etc. Can be minimized and efficient.

In this embodiment, the base station 1 transmits a regular information transmission command not only to the radio channel 41 but also to the radio channel 42. However, the wireless channel 42 may be used only for transmitting individual information, and the periodic information transmission command may be transmitted only to the wireless channel 41. However, in this case, the slave station cannot receive the periodic information transmission command while receiving the individual information with a large amount of information. If the periodic information transmission command cannot be received, the slave station cannot transmit information because it does not know at what timing the periodic information and temporary information may be transmitted.
Alternatively, in order to receive the periodic information transmission command, it is also conceivable to switch the reception channel back to the wireless channel 41 and then switch to receiving the wireless channel 42 again. However, it is necessary to frequently switch the communication channel, and a delay occurs due to the adjustment accompanying the switching.
If the regular information transmission command is transmitted also to the wireless channel 42 as in this embodiment, the regular information transmission command can be received even when the taxi receives a signal from the wireless channel 42. If it does so, even if it is in the middle of receiving individual information by the wireless channel 42, the taxi 2a-2e can know the timing which can transmit regular information and temporary information, and is preferable.

1 is a diagram illustrating an overall configuration of a communication system according to Embodiment 1. FIG. FIG. 3 shows an internal configuration of a base station in the first embodiment. FIG. 3 shows an internal configuration of a taxi in the first embodiment. FIG. 6 illustrates an example of communication timing in Embodiment 1; The figure which shows the structure of the flame | frame which caught the timing of communication of FIG. 4 notionally. The figure which shows an example of the memory content of the regular information transmission time slot | zone memory | storage part and arbitrary transmission time slot | zone memory | storage parts in Embodiment 1 and Embodiment 3. FIG. The figure which shows an example of the signal format of the uplink communication in Embodiment 1, Embodiment 2, and Embodiment 3. FIG. FIG. 6 is a diagram illustrating an example of a signal format for downlink communication in the first embodiment and the second embodiment. FIG. 3 is a diagram showing an overall configuration of a communication system in a second embodiment. FIG. 6 shows an internal configuration of a base station in the second embodiment. FIG. 6 shows an internal configuration of a taxi in the second embodiment. FIG. 10 is a diagram illustrating an example of communication timing in Embodiment 2. The figure which shows the structure of the flame | frame which caught the timing of communication of FIG. 12 notionally. The figure which shows an example of the memory content of the use channel memory | storage part in Embodiment 2, a regular information transmission time zone memory | storage part, and an arbitrary transmission time zone memory | storage part. FIG. 4 shows an overall configuration of a communication system in a third embodiment. FIG. 10 shows an internal configuration of a taxi in the third embodiment. FIG. 10 is a diagram illustrating an example of communication timing in Embodiment 3. The figure which shows the structure of the flame | frame which caught the timing of communication of FIG. 17 notionally. FIG. 10 is a diagram illustrating an example of a signal format for downlink communication in the third embodiment.

Explanation of symbols

  10 communication system, 1 base station, 11 master station transmitter, 111 modulator, 112 antenna, 12 master station receiver, 121 demodulator, 122 antenna, 13 master station time measuring unit, 131 timer, 132 counter, 141 periodical information Transmission command generation unit, 142 Individual information signal generation unit, 15 Arbitrary transmission station determination unit, 151 Decoding unit, 152 Transmission station information identification unit, 153 Arbitrary transmission time zone storage unit, 161 Periodic transmission station identification unit, 162 Periodic information transmission time Band storage unit, 17 control unit, 18 data storage unit, 19 terminal, 2a to 2t taxi, 21 slave station transmitter, 211 modulator, 212 antenna, 22 slave station receiver, 221 demodulator, 222 antenna, 23 slave station Time measurement unit, 231 timer, 232 counter, 241 Periodic information signal generation unit, 242 Temporary information signal generation , 251 decoding unit, 252 periodic information transmission command determination unit, 261 periodic information transmission time zone storage unit, 262 arbitrary transmission time zone storage unit, 27 control unit, 281 GPS receiver, 282 toll meter, 283 emergency call button, 291 car navigation 292 Speakers, 30 frames, 301 to 308 slots, 31 slots for transmitting periodic information collection commands, 32 slots for transmitting individual information, 33 slots for transmitting temporary information, 41 to 44 wireless channels, 411a to 411b Periodic information transmission command, 412a Individual information, 413 Channel switching command, 421a Periodic information transmission command, 422a Individual information, 431a to 431e Periodic information, 432a to 432b Temporary information, 441a to 441e Periodic information, 442a Temporary information, 50 Downlink communication Signal Formatting, 51 identifiers, 52 object number, 53 division number, 54 division number, 55 data, 60 uplink communication signal formats, 61 identifiers, 62 vehicle number, 63 division number, 64 division number, 65 data.

Claims (2)

In a master station that communicates with a plurality of slave stations via uplink communication channels and downlink communication channels,
In accordance with a predetermined signal format, a periodic information transmission command for requesting transmission of periodic information to one or more of the plurality of slave stations is generated as information to be communicated through a downlink communication channel, and the generated downlink communication A periodic information transmission command generation unit that outputs information communicated by a channel;
Information for communicating individual information including information to be transmitted to one or more specific slave stations among the plurality of slave stations in accordance with a signal format common to the signal format for generating the periodic information transmission command as information transmitted through a downlink communication channel An individual information signal generation unit that generates and outputs information to be communicated through the generated downlink communication channel;
Enter the information to be communicated by the downlink communication channel output by any of the above periodic information transmission command generating unit and the individual information signal generating unit, and a master station transmitting unit that transmits the information entered in the downlink communication channel Prepared,
The periodic information transmission command generation unit and the individual information signal generation unit each have an identifier for identifying whether the information communicated by the downlink communication channel is a periodic information transmission command or individual information as the signal format. Generating information to be transmitted to the downlink communication channel according to a signal format having an area for storing a target number representing a slave station to be transmitted and data to be transmitted to the slave station;
The periodic information transmission command generator is
When all the slave stations of the plurality of slave stations are to be transmitted, generate information to be transmitted to the downlink communication channel using the code representing the periodic information transmission command to be transmitted to all the slave stations as the identifier,
When a group of one or more slave stations among the plurality of slave stations is to be transmitted, a group number for identifying the group with the code indicating that it is a periodic information transmission command for transmitting the group as the identifier And generating information to be transmitted to the downlink communication channel as the target number,
The individual information signal generator is
When a group consisting of one or more slave stations among the plurality of slave stations is to be transmitted, a code indicating that the individual information is a group to be transmitted is used as the identifier, and a group number for identifying the group is Information to be transmitted to the downlink communication channel as the data, the information to be transmitted to the slave stations belonging to the group as the target number,
When one slave station among the plurality of slave stations is to be transmitted, a code indicating that the information is individual information for which one slave station is to be transmitted is the identifier, and the slave station number for identifying the slave station is the above-described identifier. A parent station, characterized in that information to be transmitted to the downlink communication channel is generated using the information transmitted to the slave station as the target number and the data to be transmitted to the slave station. The above master station
A master station receiver that receives a response signal to the periodic information transmission command from the uplink communication channel;
Starting from the time when the periodic information transmission command is transmitted by the master station transmitter , the master station time measuring unit that measures the current time, and
A time period during which transmission of a response to the periodic information transmission command received from the time when the slave station received the periodic information transmission command as a starting point is permitted for the slave station number identifying each of the plurality of slave stations. A response to the periodic information transmission command received starting from the point in time at which the slave station belonging to the group received the periodic information transmission command. A periodic information transmission time zone storage unit that stores in advance a group target periodic information transmission time zone representing a time zone in which transmission of
When the information transmitted by the master station transmission unit is a regular information transmission command for all slave stations to be transmitted, and when the response signal is received by the master station reception unit, from the regular information transmission time zone storage unit, Search for all target periodic information transmission time zone to which the time measured by the master station time measurement unit belongs, acquire a slave station number for the searched all target periodic information transmission time zone, and the response signal is the acquired slave station Identifying that the transmission is from a slave station identified by a number, the information transmitted by the parent station transmission unit is a periodic information transmission command for sending a group as a transmission target, and a response signal by the parent station reception unit Is received from the periodic information transmission time zone storage unit, the group target periodic information transmission time zone to which the group number as the target number matches and the time measured by the master station time measuring unit belongs And search, and obtains the slave station number for the group object periodic information transmission time zone retrieved, the response signal is periodically transmitted station identification identifies that the transmission from the slave station identified by the acquired slave station number The master station according to claim 1, further comprising: a master station.

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