JP6610282B2 - COMMUNICATION DEVICE, COMMUNICATION PROGRAM, AND COMMUNICATION CONTROL METHOD - Google Patents

Description

  The present invention relates to a communication device, a communication program, and a communication control method, and can be applied to, for example, an intermittent reception type wireless communication device.

  For example, communication devices (hereinafter also referred to as “transmission device” or “reception device”) that constitute a sensor network perform power-saving communication. As a typical method of power saving communication, there is a method in which a communication device operates intermittently. For example, CSL (Coordinated Sampled Listening) is a communication standard that adopts the intermittent operation method of this communication device (Non-patent Document 1). See).

  For communication devices that employ CSL, the CSL reception cycle (CSL Period), the maximum CSL reception cycle (CSLMaxPeriod), the start-up time (wake-up reception time) at which the wake-up frame can be intermittently received are set for each communication device. Keep it.

  The transmitting device S that intends to transmit data first executes a data transmission operation in the asynchronous transmission mode. Asynchronous transmission mode is as follows. The transmitting device S continuously transmits the wake-up frame to the receiving device R for the maximum CSL reception period. In the wake-up frame, a rendezvous time (RZTime) indicating the remaining time until data transmission is described. When the transmission of the wakeup frame for one maximum CSL reception period is completed, the data frame is continuously transmitted to the receiving device R.

  The receiving device R is in a reception standby state only during the activation time within one CSL reception cycle, and does not perform a reception operation during other times. If a wake-up frame from the transmission device S is received during reception standby, the rendezvous time in the frame is acquired. Then, it starts after sleeping until just before the rendezvous time (in a reception standby state), and receives a data frame from the transmission device S.

  When receiving the data frame, the receiving device R returns a reception response signal (ACK) to the transmitting device S. In the ACK, a CSL reception cycle of the receiving device R and a phase (CSLPhase) indicating a difference between the time of the synchronization information in the wakeup frame and the reception time are inserted.

  If the transmitting device S does not receive an ACK from the receiving device R, the transmitting device S again transmits the wakeup frame and the data frame to the receiving device R in the asynchronous transmission mode even when the next data frame is transmitted.

  The transmission device S enters the synchronous transmission mode when receiving an ACK from the reception device R. The transmission device S maintains the reception cycle and CSL phase in the ACK and corrects synchronization with the reception device R. Then, at the time of the next data frame transmission, the transmission device S transmits the wakeup frame and the data frame at the corrected transmission timing.

IEEE Std 802.15.4eTM-2012

  However, even in a communication device that employs the above-described CSL, the power consumption increases as the startup time becomes longer. For example, if the total network traffic increases due to an increase in the number of surrounding communication devices, etc., the communication device on the receiving side needs to have a longer startup time for confirmation of reception, resulting in an increase in power consumption. Will do.

  Therefore, a communication device, a communication program, and a communication control method that can efficiently communicate while reducing power consumption of the communication device are desired.

According to a first aspect of the present invention, there is provided a wireless communication unit that performs wireless communication with an opposing communication device, and a control processing unit that performs control processing so as to intermittently communicate with the opposing communication device using the wireless communication unit. The control processing unit includes: (1) a reception frame counter that counts the number of frames received using the wireless communication unit; and (2) at least a first according to the reception frame counter. A communication control unit that selects one frame reception method from among a plurality of frame reception methods including the second frame reception method and the second frame reception method, and controls the wireless communication unit; ) The first frame reception method is a method that consumes less power in the wireless communication unit and the control processing unit than the second frame reception method, and the second frame reception method includes the first frame reception method. Compared to the frame reception scheme, the probability of reception of the frame by the wireless communication unit receives Ri is high scheme der, (4) the communication control unit, the received signal strength each time it receives a frame from the communication device to the opposite A reception signal strength measurement unit that measures the received signal strength, and the reception frame counter counts that there is a reception frame if the reception signal strength measured using the reception signal strength measurement unit is equal to or greater than a predetermined threshold. characterized in that it.

A communication program according to a second aspect of the present invention includes a wireless communication unit that wirelessly communicates with an opposing communication device, and a control process that performs control processing so as to intermittently communicate with the opposing communication device using the wireless communication unit. A computer installed in the control processing unit constituting a communication device comprising: (1) a received frame counter that counts the number of frames received using the wireless communication unit; and (2) a received frame counter. Accordingly, a communication control unit that controls at least one of the plurality of frame reception methods including the first frame reception method and the second frame reception method, and controls the wireless communication unit. (3) The first frame reception method uses less power in the wireless communication unit and the control processing unit than the second frame reception method. , And the second frame receiving method, compared to the first frame receiving method, wherein Ri receiving a high probability method der frames by the wireless communication unit receives, (4) the communication control unit, It further includes a received signal strength measuring unit that measures received signal strength every time a frame is received from the opposing communication device, and the received frame counter has a received signal strength measured using the received signal strength measuring unit, If it is equal to or greater than a predetermined threshold, it is counted that there is a received frame .

According to a third aspect of the present invention, there is provided: a wireless communication unit that performs wireless communication with an opposing communication device; and a control processing unit that performs control processing so as to intermittently communicate with the opposing communication device using the wireless communication unit. A communication control method performed by the control processing unit constituting the communication device provided, wherein the control processing unit includes a reception frame counter unit and a communication control unit, and (1) the reception frame counter unit includes the wireless (2) The communication control means includes at least a first frame reception method and a second frame reception method in accordance with the reception frame counter means. One frame receiving method is selected from a plurality of frame receiving methods to control the wireless communication unit. (3) The first frame receiving method is changed to the second frame receiving method. In addition, the power consumption of the wireless communication unit and the control processing unit is low, and the second frame reception method uses a frame received by the wireless communication unit as compared with the first frame reception method. receiving a high probability method der is, (4) the communication control unit, the counter communication apparatus further includes a received signal strength measurement unit for measuring a received signal strength each time it receives a frame from which the received frame counter Is characterized in that a received frame is counted if the received signal strength measured using the received signal strength measuring unit is equal to or greater than a predetermined threshold value .

  ADVANTAGE OF THE INVENTION According to this invention, it can communicate efficiently, reducing the power consumption of a communication apparatus.

It is a block diagram shown about the functional structural example of the radio | wireless communication apparatus which concerns on 1st Embodiment. 1 is a block diagram illustrating an example of the overall configuration of a wireless communication system according to a first embodiment. It is a block diagram which shows the hardware structural example of the radio | wireless communication apparatus which concerns on 1st Embodiment. It is a flowchart which shows operation | movement of the RSSI detection mode of the radio | wireless communication apparatus (receiving side) which concerns on 1st Embodiment. 6 is a flowchart showing frame reception mode switching control (operation) of the wireless communication apparatus (reception side) according to the first embodiment. It is explanatory drawing which imaged the number of the frames which the radio | wireless communication apparatus which concerns on 1st Embodiment receives with time progress. It is explanatory drawing which shows the relationship between the number of reception in the RSSI detection mode and CSL intermittent reception mode of the radio | wireless communication apparatus which concerns on 1st Embodiment, and power consumption. It is a sequence diagram which shows operation | movement of the radio | wireless communications system of 2nd Embodiment.

(A) First Embodiment Hereinafter, a first embodiment of a communication device, a communication program, and a communication control method according to the present invention will be described in detail with reference to the drawings.

(A-1) Configuration of the First Embodiment FIG. 2 is a block diagram illustrating an example of the overall configuration of the wireless communication system 1 according to the first embodiment.

  FIG. 2 illustrates a case where the wireless communication system 1 includes two wireless communication devices 10 (10-1, 10-2) for ease of explanation. Of course, the number of the wireless communication devices 10 is not particularly limited.

  Note that the communication method of the wireless communication device 10 (10-1, 10-2) is not limited, and various wireless LAN interfaces can be applied, for example. For example, the wireless communication device 10 (10-1, 10-2) adopts the IEEE Std 802.15.4eTM-2012 wireless communication scheme.

  FIG. 3 is a block diagram illustrating a hardware configuration example of the wireless communication apparatus according to the first embodiment.

  In FIG. 3, the wireless communication device 10 includes a CPU (Central Processing Unit) 11, a clock oscillation unit 12, a clock conversion unit 13, a memory 14, and a wireless communication unit 15.

  The CPU 11 is a processor that executes various processing programs (communication control programs and the like) developed in the memory 14.

  The memory 14 is a primary storage area that can be directly accessed by the CPU 11.

  The clock oscillator 12 generates (oscillates) a clock having a specific frequency to be supplied to the CPU 11. The clock oscillator 12 supplies the generated clock to the clock converter 13.

  The clock conversion unit 13 converts the clock supplied from the clock oscillation unit 12 into a clock having a desired frequency. The clock conversion unit 13 supplies the converted clock to the CPU 11.

  The wireless communication unit 15 is a component that transmits and receives wireless signals via an antenna.

  FIG. 1 is a block diagram illustrating a functional configuration example of a wireless communication apparatus according to the first embodiment.

  In FIG. 1, the radio communication device 10 includes an RSSI (Received Signal Strength Indication) measurement unit 111, a frame detection unit 112, a frame analysis unit 113, a reception counter unit 114, a communication control unit 115, a frame generation unit 116, and a frame transmission unit 117. And a clock control unit 118. Note that each or all of the components of the wireless communication apparatus 10 illustrated in FIG. 1 may be configured as software. For example, the wireless communication apparatus 10 may control each component illustrated in FIG. 3 by developing a control processing unit including each component illustrated in FIG. 1 as a program in the memory 14 and executing the program by the CPU 11. .

  The wireless communication device 10 is an intermittent reception type wireless communication device. The wireless communication device 10 operates in an intermittent reception period (start-up time) in which frame transmission / reception processing is performed and a sleep period in which frame transmission / reception processing is stopped. In the sleep period, the wireless communication device 10 performs control to stop the power supply to the wireless communication unit 15 and the CPU 11 or reduce the supply amount.

  The RSSI measuring unit 111 measures the received signal strength (RSSI value) at the time of receiving a radio signal every time the wireless communication unit 15 receives a radio signal during the intermittent reception period. The RSSI measurement unit 111 supplies the measured RSSI value to the frame detection unit 112 and the communication control unit 115 (reception counter unit 114).

  If the RSSI value is equal to or greater than a predetermined threshold (carrier sense level), the frame detection unit 112 extracts a frame from the received radio wave (radio signal reception bit information). Then, the frame detection unit 112 supplies the received frame to the frame analysis unit 113.

  When receiving the received frame, the frame analyzing unit 113 analyzes the header portion of the received frame. If the destination of the header part is itself, the frame analysis unit 113 supplies the frame to the communication control unit 115.

  The reception counter unit 114 counts the number of frame receptions (or the number of carrier senses) and holds the number of receptions per unit time (reception number counter C1).

  The communication control unit 115 performs overall control of communication processing in the wireless communication apparatus 10. For example, when there is a frame transmission request from an upper layer (not shown), the communication control unit 115 receives a wakeup frame transmission completion notification and then instructs the frame generation unit 116 to generate a frame (data frame). I do. Further, the communication control unit 115 has a function of determining a reception mode and transmission timing based on information from the received frame and the reception counter unit 114. In addition, the communication control unit 115 has a function of passing information on a transmission result and a received frame to an upper layer. The reception mode will be described in detail in the operation section.

  The frame generation unit 116 generates a transmission frame based on an instruction from the communication control unit 115. The frame generation unit 116 supplies the generated frame to the frame transmission unit 117.

  The frame transmission unit 117 has a function of transmitting a transmission frame over the network via the wireless communication unit 15.

  The clock control unit 118 has a function of controlling the clock conversion unit 13 in order to select a clock having a corresponding frequency and supply it to the CPU 11.

(A-2) Operation of the First Embodiment Next, the operation of the wireless communication system 1 of this embodiment having the above configuration will be described with reference to the drawings. First, the reception mode of the reception-side wireless communication device 10 in the wireless communication system 1 will be described. In this embodiment, the wireless communication device 10 (communication control unit 115) has three receptions: an intermittent reception mode, a prior RSSI detection type CSL intermittent reception mode (hereinafter referred to as “RSSI detection mode”), and a normal reception standby mode. Has a mode.

  The CSL intermittent reception mode is a reception mode in the CSL mode described in Non-Patent Document 1.

  The normal reception standby mode is a reception mode in which the wireless communication unit 15 is always activated and enters a reception standby state except during transmission.

  The RSSI detection mode is a developed version of the CSL intermittent reception mode. Hereinafter, description will be made by taking FIG. 4 as an example. FIG. 4 is a flowchart showing the operation of the RSSI detection mode of the wireless communication apparatus (reception side) according to the first embodiment.

  The wireless communication device 10 measures the RSSI value by the RSSI measurement unit 111 after activation (S11). If the RSSI value is equal to or greater than the threshold, the wireless communication device 10 performs the process of step S12 described later, and returns to the reception sleep state if it is less than the threshold.

  If the RSSI value is equal to or greater than the threshold value, the wireless communication device 10 extends the activation time to receive a wakeup frame and enters a reception waiting state (S12).

  If the wireless communication device 10 receives a wake-up frame addressed to its own wireless communication device, the wireless communication device 10 executes a process of step S14 described later, and if not received, returns to the reception sleep state (S13).

  Similarly to Non-Patent Document 1, the wireless communication device 10 refers to the rendezvous time RZTime in the wake-up frame, determines the activation time, and receives the data frame (S14). When receiving the data frame, the wireless communication device 10 returns an ACK. The wireless communication device 10 returns to the reception sleep state after transmitting the ACK.

  By setting the reception mode to the RSSI detection mode, the wireless communication device 10 can greatly shorten the intermittent reception time except during frame reception, thereby reducing power consumption. In particular, the RSSI detection mode is effective when the frequency of reception is low.

  Next, an operation in which the wireless communication device 10 dynamically switches the reception mode will be described. The threshold L1 is a threshold for the number of receptions at the reception counter unit 114 for switching from the CSL intermittent reception mode to the RSSI detection mode. The threshold value L2 is a threshold value for switching from the RSSI detection mode to the CSL intermittent reception mode. Note that the threshold L1 and the threshold L2 are set in the reception counter unit 114 in advance (threshold L1 <threshold L2).

  FIG. 5 is a flowchart showing reception mode switching control (operation) of the wireless communication apparatus (reception side) according to the first embodiment.

  In the CSL intermittent reception mode or the RSSI detection mode, the wireless communication device 10 activates the wireless communication unit 15 at the intermittent reception time, cancels the sleep state, and shifts to the reception standby state (S21).

  In the case of the CSL intermittent reception mode or the RSSI detection mode, the wireless communication device 10 confirms frame reception (S22). Specifically, the wireless communication device 10 confirms reception of the wakeup frame in the CSL intermittent reception mode. Moreover, the radio | wireless communication apparatus 10 measures an RSSI value by the RSSI measurement part 111 in the RSSI detection mode. When the RSSI value exceeds the carrier sense level (the reference level for determining whether the received signal strength is high or low), the wireless communication device 10 (communication control unit 115) extends the activation time and wakes up. Confirm frame reception. On the other hand, if the RSSI value is below the carrier sense level or if no wake-up frame is received, the wireless communication device 10 (communication control unit 115) proceeds to the process of step S24.

  The wireless communication device 10 receives a data frame from the opposite wireless communication device 10 (S23).

  The wireless communication device 10 updates the reception number counter C1 per unit time (counts up if received) (S24). Moreover, the radio | wireless communication apparatus 10 updates the frequency | count of RSSI detection in the RSSI detection mode. In addition to the RSSI detection mode, not only the frame addressed to the own wireless communication device 10 but also a value including noise addressed to other wireless communication devices may be used as the RSSI detection frequency. The reception number counter C1 subtracts the counter value every predetermined time so as to be the number of receptions per unit time.

  The wireless communication device 10 compares the reception number counter C1 with a threshold value (threshold value L1 or threshold value L2) (S25). When the current reception mode is the CSL intermittent reception mode, the wireless communication device 10 determines to switch the reception mode if the reception number counter C1 falls below the threshold value L1. On the other hand, when the current reception mode is the RSSI detection mode, the wireless communication device 10 determines to switch the reception mode if the reception number counter C1 exceeds the threshold L2. When switching the reception mode, the wireless communication device 10 executes the process of the next step S26, and when not switching the reception mode, the wireless communication apparatus 10 ends the process (sleeps).

  When it is determined in step S25 described above that the reception mode is to be switched, the wireless communication device 10 actually switches the reception mode (S26). Specifically, when the current reception mode is the CSL intermittent reception mode, the wireless communication device 10 switches to the RSSI detection mode. Further, when the current reception mode is the RSSI detection mode, the wireless communication device 10 switches to the CSL intermittent reception mode. Note that the wireless communication device 10 performs switching between the normal reception standby mode and other modes (CSL intermittent reception mode or RSSI detection mode) according to an instruction from an upper layer.

  When the reception mode is switched in the process of step S26 described above, the wireless communication device 10 changes (converts) the clock supplied to the CPU 11 by the clock control unit 118 (S27). Specifically, the radio communication device 10 (clock control unit 118) performs control to switch to a high frequency clock in the RSSI detection mode and to a low frequency clock in the CSL intermittent reception mode. As a modification, the wireless communication device 10 may switch to a low frequency clock even in the RSSI detection mode. However, in that case, the RSSI measurement time performed by the RSSI measurement unit 111 in the wireless communication device 10 becomes long. Further, since the synchronization accuracy also decreases, the wireless communication device 10 needs to extend the activation time and wait for reception in order to cope with the synchronization shift. Therefore, in this embodiment, in the RSSI detection mode, the wireless communication device 10 switches to a high frequency clock to shorten the RSSI measurement time.

  When the radio communication device 10 receives a large number of times, the activation time becomes long for frame reception even in the RSSI detection mode. For this reason, the wireless communication device 10 of this embodiment is designed to save power by switching the reception mode from the RSSI detection mode to the CSL intermittent reception mode and lowering the clock frequency. The radio communication apparatus 10 switches to a low frequency clock when the reception mode is the normal reception standby mode, but may switch to a high frequency clock when high speed processing is desired.

  When the activation time has passed, the wireless communication device 10 stops the wireless communication unit 15, enters a sleep state, and ends the process.

  Next, the operation (switching of the reception mode) of the wireless communication device 10 will be described using a specific example (FIG. 6). In this example, it is assumed that “3 times / minute” is set in advance as the threshold value L1 held in the reception counter unit 114, and “7 times / minute” is set as the threshold value L2. In addition, in the CSL intermittent reception mode, the start time of intermittent reception for receiving one wakeup frame is 30 milliseconds, and the RSSI detection time in one RSSI detection mode is 5 milliseconds, for receiving wakeup frames. The intermittent reception time is 30 milliseconds. The data reception time is 100 milliseconds, and the intermittent reception cycle is 1 second. Further, in the CSL intermittent reception mode, it is assumed that the power consumption during startup is halved by selecting a low-frequency clock as compared with the RSSI detection mode.

  Note that the values set for the threshold value L1 and the threshold value L2 are values assigned for explanation, and various values can be applied. FIG. 7 is an explanatory diagram illustrating a relationship between the number of receptions and power consumption in the RSSI detection mode and the CSL intermittent reception mode of the wireless communication device. In FIG. 7, initially, the RSSI detection mode has lower power consumption than the CSL intermittent reception mode, but the CSL intermittent reception mode has lower power consumption than the RSSI detection mode because of a certain number of received frames. It is shown. Thus, the power consumption reverses in the middle with the increase in the number of receptions because of the difference in clock frequency. Regardless of whether the wake-up frame is received or not, the wake-up frame reception standby is performed every one intermittent reception cycle, so the slope of the increase in power consumption is small. The values set for the threshold value L1 and the threshold value L2 are determined in consideration of the relationship shown in FIG.

  FIG. 6 is an explanatory diagram in which the wireless communication device visually images the number of frames received over time.

  The number of receptions (reception number counter C1) at time t1 is 20 times / minute. In this case, since the reception number counter C1 is larger than the threshold value L1, the wireless communication device 10 performs intermittent reception in the CSL intermittent reception mode.

  The number of receptions (reception number counter C1) at time t2 is 20 times / minute. Similarly to the above, since the reception number counter C1 is larger than the threshold value L1, the wireless communication device 10 performs intermittent reception in the CSL intermittent reception mode.

  Thereafter, while the reception frequency is 3 times / minute or more, the wireless communication device 10 performs intermittent reception in the CSL intermittent reception mode. While the number of receptions is large, the wireless communication device 10 can easily receive by setting the activation time longer than that in the RSSI detection mode. Hereinafter, the relationship between the activation time and power consumption of the wireless communication device 10 in the CSL intermittent reception mode and the RSSI detection mode will be shown by calculation.

  The activation time of the CSL intermittent reception mode for 1 minute is “(activation time of intermittent reception per second × number of seconds + data frame reception time × number of times) = 30 × 60 + 100 × 20 = 3800”.

  The activation time of the RSSI detection mode for 1 minute is “(RSSI time per second × number of seconds + wakeup frame reception time × number of times + data frame reception time × number of times) = 5 × 60 + 30 × 20 + 100 × 20 = 2900”. .

  Since the CSL intermittent reception mode that is being activated is half the power consumption of the RSSI detection mode, the ratio of the power consumption per minute is “1900 (= 3800/2): 2900”.

  From the above, it can be seen that the CSL intermittent reception mode consumes less power than the RSSI detection mode.

  The number of receptions (reception number counter C1) at time t3 is 2 times / minute. In this case, since the reception number counter C1 has fallen below the threshold L1, the wireless communication device 10 switches the reception mode from the CSL intermittent reception mode to the RSSI detection mode. After switching to the RSSI detection mode, the wireless communication device 10 refers to the threshold value L2 and determines whether to switch the reception mode.

  The number of receptions (reception number counter C1) at time t4 is 2 times / minute. In this case, since the reception number counter C1 is smaller than the threshold L2, the wireless communication device 10 performs intermittent reception in the RSSI detection mode. Thereafter, while the reception count is less than 7 times / minute, the wireless communication device 10 performs intermittent reception in the RSSI detection mode. Hereinafter, similarly to the above, the relationship between the activation time and the power consumption of the wireless communication device 10 in the CSL intermittent reception mode and the RSSI detection mode is shown by calculation.

  The activation time of the CSL intermittent reception mode for 1 minute is “30 × 60 + 100 × 2 = 2000”.

  The activation time of the RSSI detection mode for 1 minute is “5 × 60 + 30 × 2 + 100 × 2 = 560”.

  The ratio of power consumption per minute is “1000 (= 2000/2): 560”.

  From the above, it can be seen that the RSSI detection mode consumes less power than the CSL intermittent reception mode. Thus, since the RSSI detection mode is activated for intermittent reception only at the time of RSSI measurement and frame confirmation at the time of RSSI detection, if the number of receptions (the number of detections) is small, the activation time (power consumption) can be suppressed. it can.

  The number of receptions (reception number counter C1) at time t5 is 20 times / minute. In this case, since the reception number counter C1 exceeds the threshold value L1, the wireless communication device 10 switches the reception mode from the RSSI detection mode to the CSL intermittent reception mode. After switching to the CSL intermittent reception mode, the wireless communication apparatus 10 refers to the threshold value L1 and determines whether to switch the reception mode.

  The number of receptions (reception number counter C1) at time t6 is 20 times / minute. In this case, since the reception number counter C1 is larger than the threshold value L1, the wireless communication device 10 performs intermittent reception in the CSL intermittent reception mode. Thereafter, while the threshold value L1 is exceeded, the wireless communication device 10 performs intermittent reception in the CSL intermittent reception mode.

(A-3) Effects of the First Embodiment According to the first embodiment, the following effects can be obtained.

  The wireless communication device 10 can suppress power consumption by switching to the CSL intermittent reception mode when the number of receptions is large and to the RSSI detection mode when the number of receptions is small. In the RSSI detection mode, since the activation time is shortened, the wireless communication device 10 can reduce the power consumption by that amount. In the CSL intermittent reception mode, the wireless communication device 10 can perform communication efficiently by extending the activation time and facilitating reception of frames from other wireless communication devices.

  In the RSSI detection mode, the wireless communication apparatus 10 can shorten the reception detection time and increase the synchronization accuracy by increasing the clock frequency. Note that the transmission frequency of the wakeup frame is also narrowed by increasing the clock frequency of the transmission-side radio communication device 10, and the reception-side radio communication device 10 can easily detect even a short detection time. Thereby, the effect that the radio | wireless communication apparatus 10 can shorten starting time is acquired. When the reception time is long, the wireless communication device 10 can reduce power consumption by lowering the clock frequency.

  As described above, the wireless communication device 10 can perform communication efficiently without changing a reception mode and controlling a clock frequency, thereby maintaining low power consumption and causing no communication error. .

(B) Second Embodiment Next, a communication device, a communication program, and a communication control method according to a second embodiment of the present invention will be described with reference to the drawings.

(B-1) Configuration of Second Embodiment The configurations of the wireless communication device 10 and the wireless communication system 1 of the second embodiment are also shown using FIGS. 1 to 3 as in the first embodiment. Can do. In the first embodiment, the reception mode is switched according to the state (number of receptions) of the wireless communication device 10 on the reception side. On the other hand, in the second embodiment, the reception mode of the reception-side wireless communication device 10 is determined in consideration of the elements (transmission mode described later) of the transmission-side wireless communication device 10.

  Below, the structure of the radio | wireless communication apparatus 10 of 2nd Embodiment is demonstrated centering on the difference with 1st Embodiment.

  The frame generation unit 116 has two types of transmission modes: a mode in which the clock frequency is increased and the frame is transmitted, and a mode in which the clock frequency is decreased and the frame is transmitted. In addition, the frame generation unit 116 provides a “reception mode identifier” that identifies a reception mode in a frame to be transmitted (for example, a wakeup frame or a data frame). As long as the reception mode identifier can identify each mode, various values may be used. For example, the normal reception standby mode is “1”, the CSL intermittent reception mode is “2”, the RSSI detection mode is “3”, When the reception mode is not designated, “0” may be set.

  When the wireless communication device 10 is the receiving side, the frame generation unit 116 describes its own reception mode (reception mode identifier) in the frame (ACK). Note that the radio communication device 10 on the transmission side describes the reception mode identifier in the transmission frame when it is desired to instruct the data reception side to change the reception mode.

(B-2) Operation | movement of 2nd Embodiment Next, operation | movement of the radio | wireless communications system 1 of this embodiment which has the above structures is demonstrated, referring drawings. FIG. 8 is a sequence diagram illustrating an operation of the wireless communication system according to the second embodiment. In FIG. 8, the transmitting side is the wireless communication device 10-1. The receiving side is the wireless communication device 10-2.

  The wireless communication device 10-1 transmits a wakeup frame and a data frame to the wireless communication device 10-2 (S101). Note that, when the wireless communication device 10-1 does not request the wireless communication device 10-2 to switch the reception mode, the wireless communication device 10-1 does not describe the reception mode identifier in the frame to be transmitted. On the other hand, when the wireless communication device 10-1 requests the wireless communication device 10-2 to switch the reception mode, the wireless communication device 10-1 transmits the reception mode identifier described in the transmission frame.

  When the value described in the reception mode identifier of the received frame is a value other than “0” and is different from the current reception mode of the own device, the wireless communication device 10-2 switches the reception mode (S102). Note that the wireless communication apparatus 10-2 may switch the reception mode by the method described in the first embodiment, for example, even when the value described in the reception mode identifier of the reception frame is “0”. .

  The wireless communication device 10-2 describes its own reception mode in the reception mode identifier in the ACK, and transmits ACK to the wireless communication device 10-1 (S103).

  The wireless communication device 10-1 confirms the ACK from the wireless communication device 10-2 with respect to the frame transmitted in the process of step S101 described above. (S104).

  The wireless communication device 10-1 determines the transmission mode in consideration of the current transmission mode of the wireless communication device 10-1, the reception mode during ACK, and transmission success information (S105). For example, the wireless communication device 10-1 receives an ACK, and if the wireless communication device 10-2 is in the CSL intermittent reception mode, the transmission mode is based on a low frequency clock, and if it is an RSSI detection method, the transmission mode is based on a high frequency clock. decide. Then, the wireless communication device 10-1 describes the reception mode at the time of frame transmission to the next wireless communication device 10-2 as “0” (does not instruct to change the reception mode) and transmits it. In addition, if the wireless communication device 10-1 does not receive ACK, the wireless communication device 10-1 determines the transmission mode using the high-frequency clock. Then, the wireless communication device 10-1 transmits the reception mode described as “3” (RSSI detection mode) at the next frame transmission to the wireless communication device 10-2. Note that the wireless communication device 10-1 does not immediately change the clock if it does not receive an ACK once, but may be in a transmission mode in which the clock is changed if it continues for a predetermined number of times.

  Also, the wireless communication device 10-1 does not describe the reception mode in the transmission frame immediately after changing the clock of its own communication device, but describes the reception mode if it fails a predetermined number of times. You may make it do.

(B-3) Effects of the Second Embodiment According to the second embodiment, the following effects are newly produced in addition to the same effects as those of the first embodiment. The wireless communication device 10 provides a reception mode identifier in the transmission frame, and the reception-side wireless communication device 10 changes its own reception mode or transmission mode from the reception mode (reception mode identifier) in this frame. It became possible to decide. As a result, the probability that the communication modes of both sides (transmission / reception side) match increases, and even if the reception side wireless communication device 10 is in the RSSI detection mode and the activation time is short, synchronization loss is unlikely to occur and data frames are easily received. Become.

  As described above, the wireless communication device 10 can maintain low power saving by preventing excessive activation and processing.

(C) Other Embodiments The present invention is not limited to the above-described embodiments, and may include modified embodiments as exemplified below.

  (C-1) In each of the above embodiments, the example in which the communication apparatus of the present invention is applied to a wireless communication apparatus that performs CSL communication has been described. However, the present invention is not limited to this, and communication that performs communication using various communication methods. It can be applied to the device.

  (C-2) In each of the above embodiments, the switching between the normal reception standby mode, the CSL intermittent reception mode, and the RSSI detection mode is left to the upper layer, but the description is omitted. Depending on the number of received frames, the reception mode may be switched by the same method as in the first embodiment.

  (C-3) In each of the above embodiments, an example in which communication is efficiently performed while saving power by changing the reception time has been described. For example, instead of changing the reception time, intermittent reception is performed. You may make it change the ratio of intermittent reception time and sleep time by lengthening a period.

  (C-4) In the first embodiment, an example has been described in which the reception mode is switched by comparing the number of receptions with a threshold value. For example, if the frame reception period or transmission period is known, reception is performed. Instead of the number, the reception mode may be switched to the RSSI detection mode if this period is greater than or equal to a certain value, and the CSL intermittent reception mode otherwise.

  (C-5) In each of the embodiments described above, there is no limitation on whether the clock frequency is the same or different when the wireless communication apparatus 10 transmits a frame and receives intermittently.

  DESCRIPTION OF SYMBOLS 1 ... Wireless communication system, 10 (10-1, 10-2) ... Wireless communication apparatus, 11 ... CPU, 12 ... Clock oscillation part, 13 ... Clock conversion part, 14 ... Memory, 15 ... Wireless communication part, 111 ... RSSI Measurement unit 112 ... Frame detection unit 113 113 Frame analysis unit 114 Reception counter unit 115 Communication control unit 116 Frame generation unit 117 Frame transmission unit 118 Clock control unit C1 Reception counter , L1 ... threshold, L2 ... threshold.

Claims (7)

A communication device comprising: a wireless communication unit that performs wireless communication with an opposing communication device; and a control processing unit that performs control processing so as to intermittently communicate with the opposing communication device using the wireless communication unit,
The control processing unit
A reception frame counter that counts the number of frames received using the wireless communication unit;
According to the reception frame counter, at least one frame reception method is selected from a plurality of frame reception methods including a first frame reception method and a second frame reception method, and the wireless communication unit is A communication control unit for controlling,
The first frame reception method is a method in which power consumption of the wireless communication unit and the control processing unit is less than that of the second frame reception method,
The second frame receiving method, compared to the first frame receiving method, Ri receiving a high probability method der frame the wireless communication unit receives,
The communication control unit further includes a received signal strength measuring unit that measures a received signal strength every time a frame is received from the opposing communication device,
The communication apparatus according to claim 1, wherein the reception frame counter counts that there is a reception frame if the reception signal strength measured using the reception signal strength measurement unit is equal to or greater than a predetermined threshold . The control processing unit is configured using a processor,
When the wireless communication unit is controlled by the first frame reception method or the second frame reception method, the wireless communication unit further includes a clock conversion unit that converts a frequency of a clock supplied to the control processing unit. The communication apparatus according to claim 1 . The said communication control part further has a frame production | generation part which produces | generates the flame | frame containing the information which instruct | indicates the change of a frame reception system with respect to the said opposing communication apparatus, The Claim 1 or 2 characterized by the above-mentioned. Communication device. The first frame reception system is a system that uses a function of estimating reception of a frame by detecting a reception signal strength by the reception signal strength measurement unit at least during intermittent reception. Item 4. The communication device according to any one of Items 1 to 3 . The second frame receiving method, at least, a communication device according to any one of claims 1 to 4, characterized in that at the time of intermittent reception is a method comprising a frame receivable state each time. The communication apparatus includes: a wireless communication unit that performs wireless communication with an opposing communication device; and a control processing unit that performs control processing so as to intermittently communicate with the opposing communication device using the wireless communication unit. A computer installed in the control processor
A reception frame counter that counts the number of frames received using the wireless communication unit;
According to the reception frame counter, at least one frame reception method is selected from a plurality of frame reception methods including a first frame reception method and a second frame reception method, and the wireless communication unit is Function as a communication control unit to control,
The first frame reception method is a method in which power consumption of the wireless communication unit and the control processing unit is less than that of the second frame reception method,
The second frame receiving method, compared to the first frame receiving method, Ri receiving a high probability method der frame the wireless communication unit receives,
The communication control unit further includes a received signal strength measuring unit that measures a received signal strength every time a frame is received from the opposing communication device,
The received frame counter counts as a received frame if the received signal strength measured using the received signal strength measuring unit is greater than or equal to a predetermined threshold . The communication apparatus includes: a wireless communication unit that performs wireless communication with an opposing communication device; and a control processing unit that performs control processing so as to intermittently communicate with the opposing communication device using the wireless communication unit. A communication control method performed by the control processing unit,
The control processing unit includes reception frame counter means and communication control means,
The received frame counter means counts the number of frames received using the wireless communication unit,
The communication control means selects one frame reception method from a plurality of frame reception methods including at least a first frame reception method and a second frame reception method according to the reception frame counter means. Control the wireless communication unit,
The first frame reception method is a method in which power consumption of the wireless communication unit and the control processing unit is less than that of the second frame reception method,
The second frame receiving method, compared to the first frame receiving method, Ri receiving a high probability method der frame the wireless communication unit receives,
The communication control unit further includes a received signal strength measuring unit that measures a received signal strength every time a frame is received from the opposing communication device,
The communication control method according to claim 1, wherein the reception frame counter counts that there is a reception frame if the reception signal strength measured using the reception signal strength measurement unit is equal to or greater than a predetermined threshold .

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