JP2013005419A - Communication system, packet transmission device, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system and the like which can communicate in a short processing time by performing communication without using a long preamble.SOLUTION: A transmission terminal stores reception interval information of a reception terminal, and transmits packets including a preamble 101 and data 102 which can be received in a time shorter than a reception interval (a) indicated by the stored reception interval information (c). The reception terminal receives the packets transmitted from the transmission terminal at the reception interval indicated by the reception interval information (a).

Description

  The present invention relates to a communication system, a packet transmission device, and a program for exchanging packets between terminals.

  In a communication system that exchanges packets between terminals, communication can be reliably performed using a long preamble that is received longer than the intermittent reception interval of the receiving terminal.

  On the other hand, as a technique for changing the preamble of a packet, one described in Patent Document 1 below is known.

  In Patent Document 1, in order to enable recovery when communication fails, the length of the preamble signal is changed and the preamble signal is added to the data and transmitted when the communication is not normally completed. It is described that.

  Further, as a technique for performing intermittent communication in order to reduce the power consumption of the terminal, a technique described in Patent Document 2 below is known. In Patent Document 2, a transmitter repeatedly transmits a packet several times after an activation signal, and a receiver performs intermittent reception operation at a first time interval in order to detect the activation signal, and after detecting the activation signal. Describes detecting the packet at a second time interval.

Japanese Patent Laid-Open No. 9-65464 JP 2008-54263 A

  However, since the long preamble in the above-described conventional technique is much longer than the normal preamble, there is a problem that it takes time at the time of transmission.

  For example, long preamble transmission takes 1000 msec, and normal preamble transmission takes tens of msec. For this reason, when a wireless terminal transmits commands to a plurality of terminals in order, or when retransmission is performed when transmission fails, a long transmission time is involved. Then, it takes time until the next command is sent, and there is a problem that the immediate responsiveness is deteriorated or the time-out process or the like cannot be sent.

  Therefore, the present invention has been proposed in view of the above-described circumstances, and provides a communication system, a packet transmission device, and a program that can communicate in a short processing time by performing communication without using a long preamble. With the goal.

  A communication system according to a first invention for solving the above-mentioned problem is a communication system including a transmission terminal and a reception terminal, wherein the transmission terminal stores a storage interval information of the reception terminal, and the storage unit And a transmission unit that transmits a packet including a preamble that can be received in a time shorter than the reception interval indicated by the reception interval information stored in the reception interval information, and the reception terminal receives the transmission terminal at the reception interval indicated by the reception interval information. It has the receiving part which receives the packet transmitted from (2).

  The communication system according to the first aspect is the communication system according to the first aspect, wherein the number of retries for transmitting a packet to the receiving terminal of the transmitting terminal is a product of the length of the preamble and the number of retries from the reception interval of the receiving terminal Is set to be longer.

  In the communication system according to the first or second invention, the third invention is characterized in that the transmitting terminal receives the reception interval information of the receiving terminal from another wireless terminal.

  A packet transmission device according to a fourth invention for solving the above-mentioned problems is a packet transmission device communicable with a reception terminal, wherein the storage unit stores reception interval information of the reception terminal, and the reception stored in the storage unit And a transmission unit that transmits a packet including a preamble that can be received in a time shorter than the reception interval indicated by the interval information.

  A packet transmission device program according to a fifth invention for solving the above-described problem is a packet transmission device program capable of communicating with a reception terminal, wherein the packet transmission device computer is configured to receive reception interval information of the reception terminal. A storage unit that stores the packet and a transmission unit that transmits a packet including a preamble that can be received in a time shorter than the reception interval indicated by the reception interval information stored in the storage unit.

  According to the present invention, since the reception interval of the receiving terminal is set in advance and a packet including a preamble that can be received in a time shorter than the reception interval is transmitted, the communication is performed without using a long preamble and is short. Communication is possible in processing time.

It is a block diagram which shows the structural example of the radio | wireless communications system shown as one Embodiment of this invention. It is a block diagram which shows the structural example of the controller in the radio | wireless communications system shown as one Embodiment of this invention. It is a block diagram which shows the structural example of the wireless switch in the radio | wireless communications system shown as one Embodiment of this invention. In a wireless communication system shown as an embodiment of the present invention, (a) is a reception interval of a receiving terminal, (b) is a transmission operation of a wireless communication system as a comparative example, and (c) is a transmission of a wireless communication system of the present embodiment. It is a figure explaining operation | movement. It is a sequence diagram explaining operation | movement of the transmission terminal and intermittent reception terminal when retransmission does not occur in the radio | wireless communications system shown as one Embodiment of this invention. It is a sequence diagram explaining operation | movement of the transmission terminal and intermittent reception terminal when resending occurs in the radio | wireless communications system shown as one Embodiment of this invention. In the radio | wireless communications system shown as one Embodiment of this invention, it is a sequence diagram explaining operation | movement of a transmission terminal and an intermittent reception terminal when acquiring receiving interval information by another radio | wireless terminal.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A wireless communication system shown as an embodiment of the present invention is configured as shown in FIG. This wireless communication system includes a controller 1 as a transmission terminal and a wireless switch 2 as a reception terminal. Although FIG. 1 shows the case where the terminal connected to the controller 1 is only the wireless switch 2, it is assumed that a plurality of wireless switches and other sensors are connected. In this wireless communication system, the controller 1 communicates with the wireless switch 2 to monitor the state of the wireless switch 2 to display the ON / OFF state, power management, ON / OFF remote control, and the like. System.

  As illustrated in FIG. 2, the controller 1 includes a storage unit 11, a control unit 12, and a communication I / F 13. The controller 1 is a computer including a storage unit, a communication I / F circuit, a CPU, and a program, and the CPU executes the program. Thereby, the program of the controller 1 can communicate with the intermittent receiving terminal by controlling the preamble length and the number of retries as will be described later.

  The storage unit 11 stores reception interval information of the wireless switch 2 as a receiving terminal. The storage unit 11 may receive the operation of the system setter at the time of system setting and store the reception interval information of the wireless switch 2 or may store it in advance. The control unit 12 controls the communication operation of the communication I / F 13 using the reception interval information stored in the storage unit 11. The communication I / F 13 transmits a packet including a preamble that can be received in a time shorter than the reception interval indicated by the reception interval information stored in the storage unit 11. In other words, the communication I / F 13 divides a long preamble to be normally transmitted into N equal parts and transmits N times. For example, a packet including a long preamble and a short preamble having a length of 1/3 is transmitted three times. Accordingly, the communication I / F 13 transmits a packet (request packet) including a request command for transmitting the switch state of the wireless switch 2 to the controller 1.

  As shown in FIG. 3, the wireless switch 2 includes a switch state sensor 21 and a communication I / F 22. The switch state sensor 21 detects the current switch state. The switch state detected by the switch state sensor 21 is transmitted to the controller 1 by the communication I / F 22. The communication I / F 22 receives a request packet transmitted from the controller 1 at a reception interval indicated by the reception interval information. The communication I / F 22 transmits a switch status report packet to the controller 1 in response to the request packet.

  The wireless switch 2 is, for example, a battery driving terminal that is driven by battery power. The wireless switch 2 is in a dormant state in the normal state in order to reduce battery power consumption. Then, the wireless switch 2 becomes in an intermittently receivable state in accordance with preset reception interval information, and can receive a request packet from the controller 1.

  Next, a specific example in which the controller 1 and the wireless switch 2 communicate in the above-described wireless communication system will be described with reference to FIG. FIG. 4A shows the timing when the wireless switch 2 is activated and can receive a request packet. FIG. 4B shows communication when a long preamble is used in the conventional wireless communication system. FIG.4 (c) shows communication at the time of using a short preamble in the radio | wireless communications system in this embodiment.

  In such a radio communication system, as shown in FIG. 4A, the wireless switch 2 is activated from a dormant state at predetermined intervals T, and a request packet from the controller 1 is received only during a predetermined receivable period. It is ready to receive.

  In this wireless communication system, the reception interval of the wireless switch 2, the preamble length of the packet, and the number of packet retransmissions are set in advance.

  For example, in the conventional wireless communication system as a comparative example, the intermittent reception interval of the wireless switch 2 is 1000 msec, and the preamble length of the packet transmitted by the controller 1 can be received at 1100 msec. Further, the number of packet retransmissions in the wireless communication system as a comparative example is three.

  Such a wireless communication system as a comparative example has a long preamble 101 'as shown in FIG. The controller 1 transmits a packet including a preamble 101 'and transmission data 102', and the packet is not received by the wireless switch 2 for some reason. For example, as shown in FIG. 4B, normally, the preamble 101 ′ of the packet is received at time t1, and the wireless switch 2 is in a receivable state until receiving the transmission data 102 ′, and receives the reception data 102 ′. To do. However, the radio wave environment deteriorates due to noise and shielding, and the received data 102 'cannot be received. Thereafter, the controller 1 retransmits the packet. Then, this packet is received from time t3 to time t4.

  On the other hand, in the wireless communication system according to the present embodiment, the intermittent reception interval of the wireless switch 2 is 500 msec, and the preamble length of the packet transmitted by the controller 1 is 550 msec. Further, the number of packet retransmissions in the wireless communication system according to the present embodiment is six.

  The number of retransmissions (the number of retries) is set so that the product of the length of the preamble and the number of retries is longer than the reception interval of the wireless switch 2. Thereby, if retry is included, communication to the wireless switch 2 can be performed reliably.

  As shown in FIG. 4C, such a wireless communication system transmits a packet including the preamble 101 and transmission data 102 from the controller 1 to the wireless switch 2 at time t1. Since this packet can be received in half the reception time of the wireless communication system as a comparative example, the transmission time can be halved.

  When the wireless switch 2 can receive a request packet by one packet transmission in this way, as shown in FIG. 5, a request packet (Switch Status Get) (S1b) for obtaining a switch state from the controller 1 as a transmission terminal is obtained. Send. The preamble S1a is transmitted together with the request packet S1b. When the wireless switch 2 receives this request packet (S1a), the wireless switch 2 returns an ACK (S2) to the controller 1 to the controller 1. Thereafter, the wireless switch 2 transmits a switch status report packet (Switch Status Report) (S3) including its own switch status to the controller 1. When the controller 1 receives the switch status report packet (S3), it returns an ACK (S4) to the wireless switch 2.

  It is assumed that the packet transmitted from time t1 is not received by the wireless switch 2 for some reason. Thereafter, the controller 1 retransmits the packet and transmits the packet including the preamble 101A and the transmission data 102A, and the packet including the preamble 101B and the transmission data 102B in this order. When a packet is transmitted twice, it is necessary to transmit the packet from time t3 to time t4. In this case, the packet transmission time is the same as that of the wireless communication system as the comparative example.

  Further, as shown in FIG. 6, when the ACK for the preambles S11a and S12a and the request packets (S11b) and (S12b) is not transmitted, the controller 1 transmits the third preamble S13a and the request packet (S13b). Works like this.

  For example, if the radio wave environment temporarily deteriorates due to noise, etc., the probability of successful packet transmission at the first time is 90%, the probability of successful packet transmission at the second time is 9%, and the packet transmission at the third time Suppose the probability of success is 1%. In this case, the wireless communication system as a comparative example requires an average transmission time of 1221 msec.

That is, in the case of a wireless communication system as a comparative example, as an average transmission time,
1100 × 0.9 + (1100 * 2 * 0.09) + (1100 * 3 * 0.01) = 1,221msec
Takes time.

On the other hand, in the case of the wireless communication system of the present embodiment, if the probability that each communication succeeds at the first time, the second time, the third time, the fourth time, the fifth time, and the sixth time is the same,
550 * 0.45 + 550 * 2 * 0.45 + 550 * 3 * 0.045 + 550 * 4 * 0.045 + 550 * 5 * 0.005 + 550 * 6 * 0.005 = 946msec
Is the transmission time. Therefore, according to the wireless communication system of the present embodiment, the preamble data length is set to be shorter than the reception interval of the wireless switch 2 and the number of retransmissions is increased. Thereby, the transmission time required for transmitting one packet can be shortened.

  As described above, according to this wireless communication system, the reception interval of the wireless switch 2 is set in advance, and a packet including a preamble that can be received in a time shorter than the reception interval is transmitted. As a result, communication can be performed without using a long preamble as in a wireless communication system as a comparative example, and communication can be performed in a short processing time. That is, in the wireless communication system of the present embodiment, there is a possibility that the number of retries will increase, but there may be a case where communication can be performed once, even if there is an intermittent receiving terminal in the wireless communication system, As a whole system, the expected value of traffic per hour can be increased.

  Further, according to this wireless communication system, even when there are a plurality of wireless switches 2 as intermittent reception terminals in the wireless communication system, when the switch state is sequentially acquired, the processing in the controller 1 is performed. Time can be shortened.

  Next, another wireless communication system to which the present invention is applied will be described.

  In this wireless communication system, a transmission terminal B to an intermittent reception terminal receives reception interval information of a reception terminal from a transmission terminal A that is another wireless terminal. The transmitting terminal B may receive the reception interval information of the receiving terminal from the transmitting terminal A in advance, or can be realized both when information is included in the request packet (S21). The transmission terminal A may receive the operation of the system setter at the time of system setting and store the reception interval information of the intermittent reception terminal, or may store it in advance. The transmission terminal A corresponds to the controller 1.

  In such a wireless communication system, as shown in FIG. 7, the transmitting terminal A transmits a request packet (S21) to the transmitting terminal B, and receives an ACK (S22) from the transmitting terminal B. The transmitting terminal B receives the ACK (S26) by the third request packet (S25b) without transmitting the ACK even if the request packets (S23b) and (S24b) are transmitted. Thereafter, the transmission terminal B transmits a transfer success notification (S27) to the transmission terminal A. The transmitting terminal A returns ACK (S28). Thereafter, the intermittent receiving terminal transmits a switch status report packet (S29) to the transmitting terminal B. The transmitting terminal B transfers the switch status report packet (S30) to the transmitting terminal A.

  Thereafter, the transmitting terminal A transmits ACK (S31) to the transmitting terminal B. Thereafter, the transmitting terminal B transfers a transfer success notification (S32), and the intermittent receiving terminal returns an ACK (S33) to the transmitting terminal B.

  Thus, even when the transmission terminal A communicates with the intermittent reception terminal via the transmission terminal B, the transmission terminal B can acquire the reception interval information from the transmission terminal A. Thereby, even if it is a case where each terminal does not have reception interval information, it can communicate from an intermittent receiving terminal corresponding to a hop communication.

  The above-described embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and various modifications can be made depending on the design and the like as long as the technical idea according to the present invention is not deviated from this embodiment. Of course, it is possible to change.

DESCRIPTION OF SYMBOLS 1 Controller 2 Wireless switch 11 Memory | storage part 12 Control part 13 Communication I / F
21 Switch status sensor 22 Communication I / F

Claims (5)

In a communication system including a transmitting terminal and a receiving terminal,
The transmission terminal transmits a packet including a preamble that can be received in a time shorter than the reception interval indicated by the reception interval information stored in the storage unit, and a storage unit that stores the reception interval information of the reception terminal And
The said receiving terminal has a receiving part which receives the packet transmitted from the said transmission terminal by the receiving interval which the said receiving interval information shows.   The number of retries for transmitting a packet to the receiving terminal of the transmitting terminal is set so that the product of the length of the preamble and the number of retries is longer than the reception interval of the receiving terminal. The communication system described.   The communication system according to claim 1, wherein the transmission terminal receives reception interval information of the reception terminal from another wireless terminal. In a packet transmission device capable of communicating with a receiving terminal,
A storage unit for storing reception interval information of the receiving terminal;
And a transmission unit that transmits a packet including a preamble that can be received in a time shorter than the reception interval indicated by the reception interval information stored in the storage unit. A packet transmission device program capable of communicating with a receiving terminal,
A computer of the packet transmission device;
A storage unit for storing reception interval information of the receiving terminal;
A program for a packet transmission device for causing a packet to be transmitted as a transmission unit that includes a preamble that can be received in a shorter time than a reception interval indicated by reception interval information stored in the storage unit.

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