JP2010118804A - Communicating system, transmitter, and receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system that achieves low power consumption by shortening a time required for receiving a telegraphic message even though a carrier sense interval is made long, a transmitter and a receiver. <P>SOLUTION: A header frame of a telegraphic message transmitted by radio equipment that serves as a transmitter is provided so as to alternately transmit a discrimination code C of radio equipment desired to be transmitted and remaining time information until the transmission of the header frame finishes. A CPU in radio equipment serving as a receiver determines whether a discrimination code of the currently received telegraphic message coincides with a self discrimination code, waits for the reception of the remaining time information after determining that the discrimination code coincides to stop a telegraphic message receiving operation, and restarts the telegraphic message receiving operation again when an elapsed time from stopping the telegraphic message receiving operation reaches a time obtained by subtracting a reception preparation time from the remaining time information received just before stopping the telegraphic message receiving operation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a communication system, a transmitter, and a receiver, and in particular, a receiver that checks the presence / absence of a telegram transmitted wirelessly at a predetermined carrier sense interval and receives the telegram if there is the telegram, The present invention relates to a communication system including a transmitter configured to wirelessly transmit the telegram composed of a header longer than the carrier sense interval, and a transmitter and a receiver used in the communication system.

  As a reception method for receiving a message transmitted wirelessly from a transmitter, there are a constant reception method that always confirms the presence or absence of a message, and a carrier sense method that confirms the presence or absence of a message at every carrier sense interval. The carrier sense method naturally consumes less power than the constant reception method. Therefore, when the receiver is a battery product, the message is basically received by the carrier sense method, but even in that case, the battery consumption for confirming the presence of the message (carrier sense) is almost all of the total consumption. Occupy.

  Therefore, conventionally, in order to reduce the battery consumption for carrier sense, it has been considered to increase the carrier sense interval. The transmitter transmits a message composed of a header longer than the carrier sense interval in order to ensure that the message is received by the receiver. Therefore, if the carrier sense interval is increased, the transmission time of the message transmitted from the transmitter is also increased. For example, if the carrier sense interval is 18 s, a message transmission time of about 20 s is required. A receiver that receives such a message has a maximum message reception time of 20 s depending on the carrier sense timing.

  Therefore, when the transmission frequency from the transmitter is low, the battery consumption can be reduced by increasing the carrier sense interval. However, as the scale of the communication system increases and the frequency of transmission from the transmitter increases, the amount of battery consumption for receiving a message increases. In particular, a plurality of receivers may be divided for each unit, and a determination code may be attached to each unit. The receiver immediately stops receiving the message if it does not match its own identification code from the identification code attached to the header of the message, but it is the same as the identification code attached to each unit. Messages to other receivers belonging to the unit must be received to the end. Since the number of receptions of the transceivers constituting the unit is the number of individual transmissions × the number of transceivers constituting the unit, even if the transmission frequency of the individual transceivers does not change, there are many transceivers constituting the unit. As the number of receptions increases, the battery consumption increases. And when the reception frequency exceeds a certain level, the battery consumption for receiving the message exceeds the battery consumption reduced by increasing the carrier sense interval, and the power consumption is reduced by increasing the carrier sense interval. There was a problem that could not be expected.

  Therefore, the present invention pays attention to the above-described problems, and shortens the time required to receive a message even if the carrier sense interval is increased, thereby reducing the power consumption of the communication system, the transmitter, and the reception. It is an object to provide a vessel.

  The invention according to claim 1, which has been made to solve the above-described problem, is a receiver that checks the presence or absence of a telegram transmitted wirelessly at every predetermined carrier sense interval and receives the telegram if the telegram exists. And a transmitter that wirelessly transmits the telegram composed of a header longer than the predetermined carrier sense interval, wherein the header of the telegram transmitted by the transmitter is determined by the receiver Information and the remaining time information until the transmission of the header is completed are alternately transmitted, and the receiver determines whether or not the determination information of the message being received matches its own determination information. Determination means for determining the reception time, the reception stop means for stopping the reception of the message after waiting for reception of the remaining time information after the determination means determines that they match, and the process from the reception stop of the message A communication restarting means for restarting reception of the message again when time reaches a time obtained by subtracting a reception preparation time from the remaining time information received immediately before the reception of the message is stopped. Exist.

  According to a second aspect of the present invention, when the receiver receives the remaining time information immediately before the reception of the message is less than or equal to a threshold set to a value equal to or greater than the reception preparation time, the reception stop means 2. The communication system according to claim 1, further comprising prohibiting means for prohibiting the reception stop of the electronic message and continuing the reception of the electronic message.

  The invention according to claim 3 confirms the presence / absence of a telegram transmitted wirelessly at every predetermined carrier sense interval, and if there is the telegram, the receiver that receives the telegram is more than the predetermined carrier sense interval. In the transmitter that wirelessly transmits the message composed of a long header, the header of the message transmitted by the transmitter includes the determination information of the receiver and the remaining time information until the transmission of the header ends. Are provided so as to be transmitted alternately.

  According to a fourth aspect of the present invention, in the receiver that receives the message if there is the message by checking the presence / absence of the message transmitted wirelessly at every predetermined carrier sense interval, the determination information of the message being received is A discriminating unit that discriminates whether or not the discriminating information matches with its own discriminating information; and a reception stopping unit that waits for receiving the remaining time information of the telegram after it is discriminated by the discriminating unit and stops receiving the telegram And a reception restarting means for restarting reception of the message again when an elapsed time from the reception stop of the message reaches a time obtained by subtracting a reception preparation time from the remaining time information received immediately before the reception of the message is stopped. The receiver is characterized by comprising.

  As described above, according to the first aspect of the present invention, the receiver stops receiving the message after receiving the remaining time information after it is determined by the determining means that they match, so the carrier sense interval is Even if the length is increased, the time required for receiving the message can be shortened, and the power consumption can be reduced.

  According to the second aspect of the present invention, when the prohibition means receives the message by the reception stop means when the remaining time information received immediately before the reception of the message is equal to or less than a threshold set to a value equal to or greater than the reception preparation time. Since the suspension is prohibited and the reception of the message is continued, the transmission content transmitted after the header can be reliably received.

  According to the invention of claim 3, since the transmitter alternately transmits the determination information of the receiver and the remaining time until the transmission of the header is completed, the remaining time until the transmission of the header is completed on the receiver side. You can check the time. Therefore, even if the receiver stops receiving the message after confirming the presence of the message, the reception of the message can be resumed before the transmission content after the header is transmitted by the transmitter. Even if the length is increased, the time required for receiving the telegram of the receiver can be shortened, and the power consumption can be reduced.

  According to the fourth aspect of the present invention, since the receiver stops receiving the message after receiving the remaining time information after it is determined by the determining means that they match, the message can be received even if the carrier sense interval is increased. It is possible to shorten the time taken to receive the power and to reduce power consumption.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the communication system includes a plurality (three in this embodiment) of wireless units 11 to 13. Each of the wireless units 11 to 13 includes a plurality of wireless devices 20. As shown in FIG. 2, each of the radio devices 20 includes an antenna AT, a modem 21, and a μCOM 22.

  The antenna AT receives radio waves, converts them into electrical signals, and outputs them to a modem 21 described later. Further, the antenna AT transmits an electric signal supplied from a modem 21, which will be described later, into radio waves. The modem 21 modulates an electrical signal output from the later-described μCOM 22 and outputs it to the antenna AT. The modem 21 demodulates the electrical signal received by the antenna AT and outputs the demodulated signal to the μCOM 22 described later.

  The μCOM 22 controls the entire radio device 20. The μCOM 22 stores a CPU 22A that performs various processes according to a program, a ROM 22B that is a read-only memory that stores a program for processing performed by the CPU 22A, a work area that is used in various processes in the CPU 22A, and various data. And a RAM 22C which is a readable / writable memory having a data storage area and the like. A discrimination code as discrimination information is stored in the RAM 22C. The discrimination code is a code determined for each of the wireless units 11 to 13. That is, the discrimination codes of the radio devices 20 belonging to the same radio units 11 to 13 are the same.

  Next, the operation of the communication system 1 configured as described above will be described with reference to FIGS. When the predetermined transmission timing is reached, the CPU 22A controls the modem 21 to perform a transmission process for wirelessly transmitting the telegram having the frame configuration shown in FIG. 3 from the antenna AT. As shown in FIG. 3, the message includes a header frame FH as a header and a data frame FD. The header frame FH is provided so that the determination code C of the wireless units 11 to 13 to which the wireless device 20 to which a message is to be transmitted belongs and the remaining time information until transmission of the header frame FH ends are alternately transmitted. It has been. The header frame FH is provided so that the transmission of the discrimination code C and the remaining time information is repeated at regular intervals.

  The remaining time information is decreased by a fixed interval every time the remaining time information is transmitted. For example, if the fixed interval is set to 1.0 s, the remaining time information is decreased by 1.0 s each time the remaining number of times of transmission of the remaining time information is overlapped with 19 s, 18 s, 17 s,. In the example shown in FIG. 3, the fixed interval is set to 1.0 s for the sake of simplicity, but in practice it is set to a shorter time. The header frame FH is set to be longer than a carrier sense interval described later. For example, if the carrier sense interval is 18 s, the header frame FH is set to 19 s and the data frame FD is set to 1 s. Therefore, CPU22A transmits a message over 20s. Transmission contents are written in the data frame FD. The wireless device 20 performing this transmission processing corresponds to the transmitter in the claims.

  On the other hand, the CPU 22A performs the carrier sense process and the reception process shown in FIGS. 4 and 5 in parallel with the transmission process. The CPU 22A starts carrier sense processing in response to power-on. In the carrier sense process, the CPU 22A first sets a timer at a predetermined carrier sense interval and starts a countdown of the timer (step S1). Thereafter, the CPU 22A waits for the count value of the timer to become zero (Y in step S2), checks whether the antenna AT is receiving radio waves via the modem 21, and transmits other radio devices. The carrier sense which confirms the presence or absence of the message | telegram transmitted by radio | wireless from 20 is performed (step S3).

  If there is a telegram as a result of carrier sense (Y in step S4), the CPU 22A starts a reception process shown in FIG. 5 described later (step S5), and then returns to step S1 again. On the other hand, if there is no message as a result of performing carrier sense (N in step S4), the CPU 22A immediately returns to step S1 without starting the reception process. As is clear from the above, the carrier sense in step S3 is performed at predetermined carrier sense intervals.

  In the reception process, the CPU 22A starts a reception operation of receiving a message transmitted from another radio device 20 using the modem circuit 21 and the antenna AT (step S6). For example, as shown in FIG. 3, if the timing at which this reception operation is started is a little before 4 s have elapsed from the start of transmission of the message, the wireless device 20 receives the determination code C in response to the start of the reception operation. The CPU 22A waits to receive the determination code C written in the header frame FH of the message in response to the start of the reception operation (step S7).

  When the CPU 22A receives the determination code C (Y in step S7), the CPU 22A functions as a determination unit, and determines whether or not the received determination code C matches the determination code C of the wireless units 11 to 13 to which the CPU 22A belongs. (Step S8). If the determination codes C do not match (N in step S8), the CPU 22A determines that the message is not transmitted to the wireless units 11 to 13 to which the CPU 22A belongs and stops the reception operation (step S19). The process ends.

  On the other hand, if the discrimination codes C match (Y in step S8), the CPU 22A determines that the message has been transmitted to the wireless units 11 to 13 to which the CPU 22A belongs, and continues without stopping the reception operation. Let Thereafter, the CPU 22A waits to receive the remaining time information written in the header frame FH of the message (step S9). As shown in FIG. 3, if the timing at which the reception operation is started is a little before 4 s have elapsed from the start of transmission of the message, remaining time information indicating 15 s is received. When the remaining time information is received (Y in step S9), CPU 22A determines whether or not the received remaining time information exceeds a predetermined remaining time comparison value (step S10). The remaining time comparison value is set to a value equal to or greater than the reception preparation time described later, and corresponds to a threshold value in the claims.

  If the remaining time information does not exceed the remaining time comparison value (N in Step S10), the CPU 22A functions as a prohibition unit, and receives the remaining time until the transmission of the header frame FH and the transmission of the data frame FD. It is determined that there is not enough to stop the operation, and the reception operation is continued. As a result, when the reception of the data frame FD of the electronic message is completed (Y in step S18), the CPU 22A stops the reception operation (step S19) and ends the reception process. On the other hand, if the remaining time information exceeds the remaining time comparison value (Y in step S10), the CPU 22A has sufficient remaining time until transmission of the data frame FD after transmission of the header frame FH is completed. The remaining time information received in step S10 is stored in the RAM 22C (step S11).

  Thereafter, the CPU 22A stops the reception operation (step S12). As is clear from the above, in steps S9 to S12, the CPU 22A functions as a reception stop unit. Next, the CPU 22A sets the timer to (remaining time information-reception preparation time) and starts the countdown of the timer (step S13). Note that the reception preparation time is the time taken from when the reception operation is started until the data frame FD can actually be received. The CPU 22A waits for the count value of the timer to become 0 (Y in step S14), and resumes the receiving operation (step S15). As is clear from the above, in steps S13 to S15, the CPU 22A functions as reception restarting means. In this embodiment, since it is desired to confirm the determination code C again after restarting, the reception preparation time is set to 1 s. Therefore, as shown in FIG. 3, the reception operation is restarted 1 s before transmission of the data frame FD.

  Then, the CPU 22A waits for reception of the determination code C written in the header frame FH in response to the restart of the reception operation (step S16). When the determination code C is received (Y in step S16), the CPU 22A determines whether or not the received determination code C matches the determination codes of the wireless units 11 to 13 to which the CPU 22A belongs (step S17). If the discrimination codes C do not match (N in step S17), the CPU 22A determines that the message has not been transmitted to the wireless units 11 to 13 to which the CPU 22A belongs and stops the reception operation (step S19). The reception process ends.

  On the other hand, if the discrimination codes C match (Y in step S17), the CPU 22A determines that the message is transmitted to the wireless units 11 to 13 to which the CPU 22A belongs and continues the reception operation. Thereafter, the CPU 22A waits for the reception of the data frame FD to be completed (Y in step 18), stops the reception operation (step S19), and then ends the reception process again. The radio device 20 performing the carrier sense processing and the reception processing corresponds to the receiver in the claims.

  According to the communication system 1 described above, the header frame FH of the message transmitted by the radio device 20 acting as a transmitter is the remaining time information until the transmission of the discrimination code C of the radio device 20 to be transmitted and the header frame FH is completed. Are alternately transmitted. In addition, the CPU 22A in the radio device 20 serving as a receiver determines whether or not the determination code C of the received electronic message matches the determination code C of itself, and receives the remaining time information after it is determined that they match. The message reception operation is stopped when the message reception operation stops, and when the elapsed time from the message reception operation stop reaches the time obtained by subtracting the reception preparation time from the remaining time information received immediately before the message reception operation stop. To resume. Therefore, since the wireless device 20 acting as a receiver waits to receive the remaining time information after it is determined that the determination code C matches, the reception operation of the message is stopped, so that the reception is performed while the header frame FH is transmitted. No action is taken. As a result, even if the carrier sense interval is increased, the time required for receiving the message can be shortened, and the power consumption can be reduced.

  By the way, if the reception operation is stopped when the remaining time information is shorter than the reception preparation time, the transmission of the data frame FD is started before the radio wave can be received after the reception operation is resumed. Cannot be received. Therefore, according to the communication system 1 described above, the remaining time information received immediately before the reception of the message is stopped by the CPU 22A in the wireless device 20 serving as a transmitter is equal to or less than the remaining time comparison value set to a value equal to or greater than the reception preparation time. In this case, the reception of the message is continued by prohibiting the stop of the message reception operation. Thereby, the radio device 20 serving as a receiver can receive the data frame FD transmitted after the header frame FH.

  According to the communication system 1 described above, the wireless device 20 functions as both a transmitter and a receiver, but the present invention is not limited to this. For example, the wireless device 20 may function only one of the transmitter and the receiver.

  Further, according to the communication system 1 described above, the reception preparation time is set to such a value that the determination code C can be confirmed again after the reception operation is resumed. However, the present invention is not limited to this. The determination code C may not be confirmed after the reception operation is resumed, and may be set to a time from when the reception operation is started until reception of radio waves becomes possible.

  Further, according to the communication system 1 described above, 1 s is set as the reception preparation time, but the present invention is not limited to this. For example, if the time from when the reception operation is started until radio waves can be received is almost zero, 0 may be set as the reception preparation time.

  Further, according to the communication system 1 described above, the reception preparation time is set to the remaining time comparison value, but the present invention is not limited to this. The remaining time comparison value may be equal to or longer than the reception preparation time.

  Further, the above-described embodiments are merely representative forms of the present invention, and the present invention is not limited to the embodiments. That is, various modifications can be made without departing from the scope of the present invention.

It is a block diagram which shows one Embodiment of the communication system of this invention. It is a block diagram which shows the detail of the radio | wireless apparatus shown in FIG. It is a figure which shows the frame structure of the message | telegram which a radio | wireless apparatus transmits. It is a flowchart which shows the process sequence in the carrier sense process of CPU shown in FIG. It is a flowchart which shows the process sequence in the carrier sense process of CPU shown in FIG.

Explanation of symbols

20 Radio equipment (transmitter, receiver)
22A CPU (discriminating means, reception stopping means, receiving reunion means, prohibiting means)
FH header frame (header)

Claims (4)

Check the presence / absence of a message transmitted wirelessly at every predetermined carrier sense interval, and receive the message if there is the message, and the message composed of a header longer than the predetermined carrier sense interval. In a communication system comprising a transmitter for wireless transmission,
The header of the message transmitted by the transmitter is provided so that the determination information of the receiver and the remaining time information until the transmission of the header ends are alternately transmitted,
The receiver receives the remaining time information after it is determined by the determination means that the determination information of the message being received matches the determination information of the receiver. A reception stop means for waiting to stop receiving the message, and when the elapsed time from the reception stop of the message reaches a time obtained by subtracting a reception preparation time from the remaining time information received immediately before the reception stop of the message Means for resuming reception of a message;
A communication system comprising: The receiver stops the reception of the message by the reception stopping means when the remaining time information received immediately before the reception of the message is less than a threshold set to a value equal to or greater than the reception preparation time. The communication system according to claim 1, further comprising prohibition means for continuing reception of the electronic message. The message composed of a header longer than the predetermined carrier sense interval with respect to a receiver that receives the message if the presence or absence of the message is confirmed by checking the presence or absence of a message transmitted wirelessly at a predetermined carrier sense interval. In a transmitter that transmits
The header of the message transmitted by the transmitter is provided so that the determination information of the receiver and the remaining time information until transmission of the header ends are alternately transmitted. Transmitter. In the receiver that receives the message if there is the message by checking the presence or absence of the message that is transmitted wirelessly at every predetermined carrier sense interval,
A discriminating means for discriminating whether or not the discriminating information of the message being received matches the discriminating information of itself;
Receiving stop means for stopping the reception of the message after waiting for receiving the remaining time information of the message after it is determined by the determination means that they match;
Resuming means for resuming reception of the message again when the elapsed time from the reception stop of the message reaches a time obtained by subtracting the reception preparation time from the remaining time information received immediately before the reception stop of the message;
A receiver comprising:

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