JP5562124B2 - COMMUNICATION DEVICE, COMMUNICATION METHOD, AND PROGRAM - Google Patents

Description

  The present invention relates to improvement of response performance in a communication system. In particular, it relates to improving response performance in a wireless communication system.

In a supervisory control system using a wireless network, when it is difficult to secure a commercial power supply, a wireless station is required to operate for several years on a battery.
In the conventional technique for reducing power consumption of a radio station, the technique of Non-Patent Document 1 is generally used as a method for reducing power consumption by intermittently operating a radio station.
Further, a method called CSL (Coordinated Sampled Listening), which is a further improvement of the method of Non-Patent Document 1 and has reduced power consumption, has been proposed in the IEEE 802.15.4 standard (Non-Patent Document 2).

“Versatile Low Power Media Access for Wireless Sensor Networks”, ACM SenSys 2004, pp 95-107. 2004. IEEE P802.15.4e / D0.01, (DCN: 15-09 / 604 / r6)

In wireless communication, in order to avoid collision due to a hidden terminal problem, a technique of shifting transmission timing using means called random backoff is used.
However, in the method shown in Non-Patent Document 2, in “unsynchronized transmission” (= asynchronous transmission), since the frame length is very long, it takes a very long time to prevent the frames from colliding with each other. In “synchronized transmission” (= synchronous transmission), it is necessary to distribute the transmission timing in units of “channel sample” (= detection).
This is a factor that increases communication delay, and there is a problem that it cannot be applied to a system that requires high real-time performance such as a monitoring control system.

  One of the main objects of the present invention is to solve the above-described problems, and even when a hidden terminal problem occurs, the above-described distribution of transmission timing over a very long period is unnecessary. Therefore, the main purpose is to realize a method that achieves both low power consumption and real-time performance.

The communication device according to the present invention is
A carrier sense timing detector that detects the arrival of the carrier sense timing that arrives intermittently and notifies the arrival of the carrier sense timing;
It operates in the sleep mode in which carrier sense processing and communication frame reception are not performed until the arrival of the carrier sense timing is notified, and the sleep mode is canceled when the arrival of the carrier sense timing is notified from the carrier sense timing detection unit. A carrier sense process, and a reception unit that starts receiving a communication frame when a radio wave of a predetermined level or more is detected in the carrier sense process;
A transmission unit for transmitting a predetermined acknowledge frame;
After the carrier sensing process, the receiving unit sleeps when receiving a wake-up frame that is a communication frame preceding the data frame including actual data and for which the transmission timing of the acknowledge frame is specified without collision. When the transmission timing designated by the wakeup frame received by the receiving unit without collision is received, data is transmitted to the communication destination device that is the transmission source of the wakeup frame as a response to the wakeup frame. A communication control unit for transmitting an acknowledge frame permitting transmission of a frame from the transmission unit to the communication destination device and canceling a sleep mode of the reception unit and causing the reception unit to receive a data frame from the communication destination device; It is characterized by having .

According to the present invention, when the receiving unit receives a wake-up frame, the receiving unit is set in the sleep mode until the transmission timing specified in the wake-up frame so that no collision occurs, and transmission specified in the wake-up frame is performed. When timing arrives, the sleep mode of the receiving unit is canceled to receive the data frame.
For this reason, it is possible to avoid the occurrence of collision after receiving the wake-up frame without collision, so there is no need to distribute the transmission timing over a long period of time, achieving both low power consumption and real-time performance. The hidden terminal problem can be effectively solved.

The figure which shows the outline | summary of the communication sequence of the radio | wireless communication apparatus which concerns on Embodiment 1-3. FIG. 3 shows an example of a frame configuration in asynchronous transmission according to the first embodiment. FIG. 3 shows an example of a frame configuration in synchronous transmission according to the first embodiment. FIG. 3 is a diagram showing a configuration example of a wakeup frame according to the first embodiment. 2 is a diagram illustrating a configuration example of a wireless communication device according to Embodiment 1. FIG. FIG. 4 is a flowchart showing an operation example of a reception block according to the first embodiment. FIG. 4 is a flowchart showing an operation example of a reception block according to the first embodiment. FIG. 3 is a flowchart showing an operation example of a transmission block according to the first embodiment. FIG. 3 is a flowchart showing an operation example of a transmission block according to the first embodiment. The figure which shows the node position and radio wave reachable range of each node which concern on Embodiment 1. FIG. FIG. 4 shows an example of a frame transmission / reception sequence in asynchronous transmission according to the first embodiment. FIG. 4 shows an example of a frame transmission / reception sequence in asynchronous transmission according to the first embodiment. FIG. 4 shows an example of a frame transmission / reception sequence in synchronous transmission according to the first embodiment. FIG. 3 is a diagram illustrating a hardware configuration example of a wireless communication device according to the first to third embodiments.

Embodiment 1 FIG.
FIG. 1 shows an outline of a frame transmission / reception sequence between wireless communication apparatuses according to the present embodiment.
In FIG. 1, the wireless communication device A is a receiving node, and the wireless communication device B is a transmitting node.

The wireless communication apparatus A has a reception block that operates in a sleep mode (also referred to as a SLEEP mode) until the intermittent carrier sense timing arrives.
The SLEEP mode is an operation mode that consumes very little power.
Then, when the carrier sense timing (also referred to as detection timing) arrives, the wireless communication apparatus A performs carrier sense (detection).
Prior to the data frame transmission to the wireless communication device A, the wireless communication device B continuously transmits a plurality of wakeup frames (also referred to as W / U frames).
A set of a plurality of wakeup frames is referred to as a wakeup sequence (also referred to as a W / U sequence).
In the wake-up frame, the transmission timing of the ACK frame (acknowledge frame) that allows the wireless communication apparatus A to transmit the data frame from the wireless communication apparatus B is designated as RZtime (Rendezvous Time).
In the wireless communication apparatus A, when the wakeup frame is received without collision as a result of the carrier sense, the reception block is shifted to the SLEEP mode, and the SLEEP mode is maintained during the RZtime specified by the wakeup frame.
If the reception block detects radio waves from two or more devices during the carrier sense processing of the reception block and a collision occurs, the reception block starts receiving wake-up frames from two or more devices. Since only one device continues to transmit the wakeup frame and the other device has finished transmitting the wakeup frame, when the receiving block receives the wakeup frame from one device without collision, the receiving block is put into SLEEP mode. Transition.
In addition, when there is no need to transmit a frame before RZtime, the wireless communication apparatus A sets the transmission block to the SLEEP mode.

When RZtime arrives, the wireless communication device A cancels the SLEEP mode if the transmission block is in the SLEEP mode, and transmits a data frame to the wireless communication device B that is the transmission source of the wakeup sequence as a response to the wakeup sequence. An ACK frame permitting the transmission is transmitted from the transmission block.
In addition, the wireless communication device A cancels the SLEEP mode of the reception block, and can receive the data frame from the wireless communication device B.
The wireless communication device B receives the ACK frame from the wireless communication device A and transmits a data frame.
The data frame includes actual data (user data).
In the wireless communication device A, the reception block receives the data frame from the wireless communication device B, and when the reception of the data frame is completed, the reception block is shifted to the SLEEP mode again.

Note that there are asynchronous transmission and synchronous transmission as a transmission method of the wakeup frame of the wireless communication apparatus B.
Asynchronous transmission is a method in which the wireless communication device B does not know the carrier sense timing of the wireless communication device A, and the wireless communication device B randomly determines the transmission timing of the wakeup frame and transmits the wakeup frame.
The synchronous transmission is a method in which the wireless communication device B knows the carrier sense timing of the wireless communication device A, and the wireless communication device B transmits the wakeup frame by matching the transmission timing of the wakeup frame with the carrier sense timing. is there.

FIG. 2 shows an example of a frame structure at the time of asynchronous transmission according to the present embodiment.
In asynchronous transmission, transmission is divided into two, a wakeup sequence composed of a plurality of wakeup frames and a data frame.
The number of wake-up frames in the wake-up sequence in asynchronous transmission is common to all wireless communication apparatuses.

FIG. 3 shows an example of a frame structure at the time of synchronous transmission according to the present embodiment.
In synchronous communication, the number of wake-up frames specified in Non-Patent Document 2 (hereinafter referred to as a reference wake-up sequence) is divided into a wake-up sequence in which a random number of wake-up frames are added and a data frame. Send.
Since the number of wake-up frames added to the reference wake-up sequence is determined at random, the frame length of the wake-up sequence differs for each wireless communication device and each transmission opportunity of the wake-up sequence.

FIG. 4 shows an example of the structure of a wakeup frame.
The preamble is used for signal synchronization.
SFD (Start Frame Delimiter) is an identifier indicating the head of a frame.
The sequence number is a frame unique identifier.
The destination address is the address of the transmission destination node of the frame.
The source address is the address of the transmission node.
The frame type is a field indicating the type of frame, and is transmitted with the identifier of the wake-up frame so that it can be determined that this frame is a wake-up frame.
RZtime (Rendezvous time) is a time indicating the timing at which the wake-up sequence ends. At this time, the destination node transmits an ACK frame. RZtime is an example of transmission timing.
FCS (Frame Check Sequence) is a field for performing data error detection.
Fields other than RZtime are fields that are also used in general wireless communication.

  FIG. 5 shows a configuration example of radio communication apparatus 100 according to the present embodiment.

The reception block 101 receives a communication frame while performing management of a physical interface, management of a transmission control procedure, management of a network connection procedure, and the like.
The reception block 101 has three operation modes: a SLEEP mode that consumes very little power, a carrier sense mode that measures the radio field intensity of the received signal, and a reception mode that can demodulate the received signal and receive a frame. The sequence shown in FIG. 6 and FIG. 7 is executed, and when the data frame and the wake-up frame addressed to itself are received, the data frame and the wake-up frame are output to the upper layer processing block 105.
That is, the reception block 101 operates in the SLEEP mode in which the carrier sense processing and the reception of the communication frame are not performed until the detection timing (carrier sense timing) is notified from the intermittent operation control block 104 described later, and intermittent operation control is performed. When the arrival of the detection timing is notified from the block 104, the SLEEP mode is canceled and the carrier sense process is started. When the radio field intensity of a predetermined level or more is detected in the carrier sense process, the communication mode ( (Wake-up frame) reception starts.
The reception block 101 shifts to the SLEEP mode when instructed to shift to the SLEEP mode by an upper layer processing block 105 described later, and further cancels the SLEEP mode by the upper layer processing block 105 and enters the reception mode. When instructed to shift, the mode shifts to a reception mode, and a data frame is received from a communication destination wireless communication device (communication destination device).
The instruction to shift to the SLEEP mode from the upper layer processing block 105 is performed, for example, when the wakeup frame can be received without collision or when reception of the data frame is completed. The instruction to shift to the reception mode is performed when, for example, the RZtime specified in the wakeup frame arrives.
The reception block 101 is an example of a reception unit.

The transmission block 102 transmits a communication frame while performing management of a physical interface, management of a transmission control procedure, management of a network connection procedure, and the like.
The transmission block 102 has two operation states of a SLEEP mode with very low power consumption and a transmission mode for transmitting a wake-up sequence and a data frame, receives an operation command and a transmission frame from the upper layer processing block 105, The operations shown in FIGS. 8 and 9 are executed.
That is, in the transmission block 102, when the reception block 101 receives a wakeup frame (when the wireless communication apparatus 100 corresponds to the wireless communication apparatus A in FIG. 1), the RZtime specified in the wakeup frame is When it arrives, it shifts from the SLEEP mode to the transmission mode based on an instruction from the upper layer processing block 105 and transmits the ACK frame to the communication destination device (corresponding to the wireless communication device B in FIG. 1) that is the transmission source of the wakeup frame To do.
When there is data to be transmitted in the upper layer processing block 105 (when the wireless communication apparatus 100 corresponds to the wireless communication apparatus B in FIG. 1), transmission is performed from the SLEEP mode based on an instruction from the upper layer processing block 105. The wakeup frame is transmitted to the communication destination device (corresponding to the wireless communication device A in FIG. 1) by shifting to the mode, and the data frame including the transmission target data is transmitted to the communication destination device when the RZtime arrives. To do.
The transmission block 102 is an example of a transmission unit.

  The switch 103 outputs a signal from the transmission block 102 to the antenna only during a period in which the transmission block 102 outputs a frame. Otherwise, the switch 103 outputs a signal input from the antenna to the reception block 101. It is supposed to be.

The intermittent operation control block 104 detects the arrival of the detection timing and notifies the reception block 101 of the arrival of the detection timing.
The intermittent operation control block 104 is an example of a carrier sense timing detection unit.

When the wireless communication device 100 corresponds to the wireless communication device A in FIG. 1, the upper layer processing block 105 sets the reception block 101 to SLEEP when the reception block 101 receives the wake-up frame without collision for the first time after the carrier sense processing. Switch to mode.
If the reception block 101 detects radio waves from two or more devices during the carrier sense process of the reception block 101 and a collision occurs, the reception block 101 receives a wakeup frame from two or more devices. To start.
Since only one node device continues to transmit the wakeup frame and the other node devices have finished transmitting the wakeup frame, the reception block 101 receives it when receiving only the wakeup frame from one node device. Move block 101 to SLEEP mode.
The upper layer processing block 105 shifts the transmission block 102 from the SLEEP mode to the transmission mode when the RZtime designated by the wakeup frame received by the reception block 101 arrives, and as a response to the wakeup frame. An ACK frame (acknowledge frame) that permits transmission of a data frame is transmitted from the transmission block 102 to the communication destination device to the communication destination device (corresponding to the wireless communication device B in FIG. 1) that is the transmission source of the wakeup frame.
Furthermore, when the wireless communication apparatus 100 corresponds to the wireless communication apparatus B in FIG. 1, the upper layer processing block 105 shifts the transmission block 102 from the SLEEP mode to the transmission mode for wakeup frame transmission and wakes up. Send a frame.
When the RZtime designated by the wakeup frame arrives, the upper layer processing block 105 sets the reception block 101 to receive the ACK frame from the communication destination device (corresponding to the wireless communication device A in FIG. 1). The ACK frame is transmitted by shifting from the SLEEP mode to the reception mode.
Further, after receiving the ACK frame, the upper layer processing block 105 causes the transmission block 102 to transmit the data frame.
The upper layer processing block 105 is an example of a communication control unit.

  Next, the operation (reception step) of the reception block 101 will be described with reference to FIGS.

The initial state of the reception block 101 is the SLEEP mode state (S601).
From this state, the operation starts when the following three external inputs are received (S602).
(1) Detection timing notification from intermittent operation control block 104 (2) When there is a carrier sense request from transmission block 102 (3) When there is a reception activation request from upper layer processing block 105

In the case of (1) above, when the intermittent operation control block 104 detects the arrival of the detection timing (carrier sense timing detection step) and a detection timing notification is issued (YES in S603), the reception block 101 The process shifts to the sense mode (S604).
When the radio wave intensity of a predetermined level or higher is not detected in the carrier sense (NO in S605), the reception block 101 shifts to the SLEEP mode (S601) and returns to the input waiting of the above (1) to (3) (S602). .
When a radio field intensity of a predetermined level or higher is detected (YES in S605), the mode shifts to a reception mode (S606) and waits for reception of a wakeup frame (S607).
If the radio wave is interrupted before receiving the wakeup frame (NO in S608), or if a wakeup frame not addressed to itself is received (NO in S609), the receiving block 101 shifts again to the SLEEP mode (S601). Then, the process returns to waiting for external input (S602).
When the wakeup frame addressed to the mobile terminal is received (YES in S609), the reception block 101 outputs the wakeup frame to the upper layer processing block 105 (S610).
At this time, the reception block 101 differs in processing depending on whether or not the upper layer processing block 105 is instructed to shift to the SLEEP mode (S611).
When the transition to the SLEEP mode is instructed, the wakeup frame can be received without collision, and when the transition to the SLEEP mode is not instructed, the collision occurs in reception of the wakeup frame.
When the upper layer processing block 105 is requested to shift to the SLEEP mode (NO in S612), the receiving block 101 shifts to the SLEEP mode (S601) and returns to waiting for external input (S602).
On the other hand, when the transition from the upper layer processing block 105 to the SLEEP mode is not instructed (YES in S612), the reception block 101 continues the reception mode and outputs the received wakeup frame to the upper layer processing block 105 (S613). ).

If the above condition (2) is met (YES in S614), the receiving block 101 shifts to the carrier sense mode (S616). If the radio wave intensity exceeding the predetermined level is not detected, the output without carrier detection is output. When the radio field intensity exceeding a predetermined level is detected, an output with carrier detection is output to the transmission block 102 (S617).
Thereafter, the mode shifts to the SLEEP mode.
In the case of (2) above, when the transmission block 102 transmits a wakeup frame, the reception block 101 performs carrier sense in order to avoid collision with another wireless communication device.

When the above condition (3) is satisfied (NO in S614), the reception block 101 shifts to the reception mode (S615), and when a frame (ACK frame or data frame) is received, the received frame is processed by higher layer processing. Output to block 105.
When the upper layer processing block 105 is requested to shift to the SLEEP mode (NO in S612), the receiving block 101 shifts to the SLEEP mode (S601) and returns to waiting for external input (S602).
On the other hand, when the transition from the upper layer processing block 105 to the SLEEP mode is not instructed (YES in S612), the reception block 101 continues the reception mode and outputs the received frame (data frame) to the upper layer processing block 105. (S613).

  Next, the operation (transmission step) of the transmission block 102 will be described with reference to FIGS.

The initial state of the transmission block 102 is the SLEEP mode state (S801).
The transmission block 102 operates by receiving three types of commands and transmission frames output from the upper layer processing block 105 (S802).
The types of commands are the following a) to c).
a) Asynchronous wakeup sequence transmission command b) Synchronous wakeup sequence transmission command c) Data frame transmission command

When the a) asynchronous wakeup sequence transmission command of a) is received (YES in S803), the transmission block 102 first adjusts the transmission timing in units of wakeup frames (S804), and receives the carrier sense request. It is issued to 101 (S805).
When it is confirmed by the carrier sense of the reception block 101 that there is no other transmitting node (YES in S806), the transmission block 102 shifts to the transmission mode (S807) and performs the asynchronous wake-up sequence of FIG. Transmit (S808).
It is assumed that the length of the asynchronous wakeup sequence (the number of asynchronous wakeup frames) is determined in advance by the system.
When the transmission of the asynchronous wakeup sequence ends, the transmission block 102 unconditionally shifts to the SLEEP mode (S801) and waits for the next command (S802).
The transmission block 102 and the reception block 101 operate independently, and the mode of each block is controlled separately.

If the b) synchronous wakeup sequence transmission command is received (YES in S809), the transmission block 102 first determines the wakeup sequence length (number of wakeup frame frames) using a random number. (S810).
Next, the transmission block 102 waits for the detection timing of the destination node (S811), and issues a carrier sense request to the reception block 101 in accordance with the detection timing (S812).
When it is confirmed by carrier sense of the reception block 101 that there is no other transmitting node (YES in S813), the transmission block 102 shifts to the transmission mode (S814) and transmits a wakeup sequence for synchronous transmission. (S815).
Note that the upper layer processing block 105 notifies the transmission block 102 of the detection timing of the destination node.
When transmission of the wake-up sequence for synchronous transmission is completed, the transmission block 102 unconditionally shifts to the SLEEP mode (S801) and waits for the next command (S802).

When receiving the data frame transmission command of c), the transmission block 102 adjusts the transmission timing (S816) and issues a carrier sense request to the reception block 101 (S817).
If it is confirmed by carrier sense of the reception block 101 that there is no other transmitting node (YES in S818), the transmission block 102 shifts to the transmission mode (S819) and transmits a data frame (S820).
The upper layer processing block 105 outputs the frame to be transmitted.
When the transmission of the data frame is finished, the transmission block 102 unconditionally shifts to the SLEEP mode (S801) and waits for the next command (S802).
8 and 9 are omitted because they are complicated, but when receiving an instruction to transmit an ACK frame from the upper layer processing block 105, the transmission block 102 transmits the ACK frame.

  Next, the operation (communication control step) of the upper layer processing block 105 will be described.

The upper layer processing block 105 outputs transmission data and a transmission mode to the transmission block 102 when a transmission request is generated.
In the transmission mode, when the destination node is not intermittently operated (when the destination node is always performing carrier sense), data is transmitted in the normal mode.
In addition, when the destination node is intermittently operated and the destination node does not know the detection timing (when the destination node intermittently performs carrier sense and the carrier sense timing of the destination node is unknown), it is asynchronous. Transmit wakeup sequence in mode.
Also, when the destination node operates intermittently and knows when the destination node detects (when the destination node intermittently senses the carrier and knows the carrier sense timing of the destination node) Transmits the wake-up sequence in the synchronous mode.
As a method of knowing the detection timing of the destination node, the method shown in Non-Patent Document 2 can be used.

When the upper layer processing block 105 receives a wake-up frame from the reception block 101, it issues a SLEEP request to the reception block 101, and after the RZtime has elapsed according to the value indicated in the RZtime field, Instruct the transmission of the ACK frame to the transmission source of the wakeup frame in the normal transmission mode.
At the same time, the upper layer processing block 105 outputs a reception activation request to the reception block 101 (requests transition from the SLEEP mode to the reception mode).
Further, the upper layer processing block 105 issues a SLEEP request to the reception block 101 when reception of the data frame from the transmission source node of the wakeup frame is completed.

  In the above, if there is a communication request, such as when there are multiple data frames from the wakeup frame transmission source node or when communication is performed with a node other than the wakeup frame transmission source node, immediately SLEEP is not necessary, and SLEEP may be performed after negotiation with the communication partner station.

Next, an operation when a collision occurs at the receiving node due to the hidden terminal problem will be described.
A case will be described in which two transmitting nodes A and B are in positions where radio waves do not reach each other and data is transmitted using synchronous transmission to a receiving node C where radio waves reach each other.
Each node position and the reach | attainment range of an electromagnetic wave are shown in FIG.
Each of the nodes A to C corresponds to the wireless communication device 100 in FIG.

Assume that both node A and node B have made communication requests to node C at the same time.
The upper layer processing block 105 of each node simultaneously instructs the transmission block 102 to transmit a wakeup sequence by asynchronous transmission.
Each of the transmission blocks 102 of the node A and the node B transmits a wake-up sequence if the carrier sense is not detected as a result of carrier sense after the transmission timing is adjusted at random for each wake-up frame.
Here, the transmission start timings of the node A and the node B are shifted by a random number by a multiple of the wakeup frame length.
Since node A and node B cannot detect the radio waves transmitted from each other, the carrier sense results in no carrier and both nodes transmit.
Accordingly, at the position of the node C, a collision occurs in part or all of the wake-up sequence transmitted by the node A and the node B.

Node C performs detection operation at regular intervals according to notification from intermittent operation control block 104.
As shown in FIG. 11, in the case where no collision occurs at the time of detection, a wakeup frame may be received and an ACK frame may be transmitted after the time indicated by RZtime.
In the example of FIG. 11, the transmission node A transmits a wakeup sequence at the detection timing of the reception node C, but the transmission node B does not start transmission of the wakeup sequence.
For this reason, the receiving node C receives the wake-up frame from the transmitting node A without collision.
In the receiving node C, since the upper layer processing block 105 instructs the receiving block 101 to shift to the SLEEP mode simultaneously with the reception of the wakeup frame from the transmitting node A, the wakeup frame from the transmitting node B is received by the receiving node C. Not received by C.
Then, the receiving node C waits until the RZtime specified in the wake-up frame from the transmitting node A arrives, and upon arrival of the RZtime, the upper layer processing block 105 instructs the transmission block 102 to transmit an ACK frame, An ACK frame is transmitted to the transmitting node A.
When the wake-up sequence of the transmitting node B is continued at the transmission timing of the ACK frame, the ACK frame is transmitted after the wake-up sequence of the transmitting node B is completed.
On the transmitting node side, it is possible to receive an ACK frame even after the RZtime has elapsed by ensuring a sufficient timeout period of the ACK frame for the wake-up sequence.
In this way, the transmission node A that has received the ACK frame can transmit the data frame.
When the receiving node C receives the wake-up frame (retry) from the transmitting node B without collision at the detection timing after receiving the data frame from the transmitting node A, the receiving node C receives the RZtime in the same manner as described above. The ACK frame is transmitted, and the transmission node B that has received the ACK frame transmits the data frame.

In addition, as shown in FIG. 12, when a collision occurs at the time when the reception node C detects, the reception node C continues reception until the collision is resolved in the wakeup frame reception process of the reception block 101. Therefore, if the transmission timings of the wakeup sequences of the transmitting node A and the transmitting node B are not the same, it is possible to receive the wakeup frame of the node whose transmission start is late.
Specifically, since the transmission timing of the wakeup sequence of the transmission node A is later than that of the transmission node B, the reception node C collides the wakeup frame from the transmission node A after the transmission of the wakeup sequence of the transmission node B is completed. Can be received without.
Thereafter, the receiving node C sets the receiving block 101 to the SLEEP mode until the arrival of RZtime, and transmits the ACK frame when the RZtime arrives, thereby receiving the data frame from the transmitting node A.

  In addition, even when the transmission timings of the node A and the node B are exactly the same, the transmission timing is readjusted by retrying, so that data communication is possible.

Next, a case where synchronous communication is used in the relationship between the same nodes A, B, and C will be described.
When synchronous communication is used, the frame shown in FIG. 3 is transmitted.
In the wake-up sequence for synchronous communication, the number of additional wake-up frames to be added to the reference wake-up sequence is determined at random. Therefore, transmission with a large additional amount is performed according to the processing procedure of the reception block 101 in FIGS. The node wakeup frame can be received, and data transmission / reception can be performed in the same procedure as asynchronous communication.
A specific example is shown in FIG.
In the example of FIG. 13, the transmission node A and the transmission node B transmit the wake-up sequence in synchronization with the detection timing of the reception node C, so that collision occurs.
Reception node C continues reception until reception block 101 resolves the collision.
Then, since the wake-up sequence of the transmitting node B with a small number of additional wake-up frames ends first, the receiving node C receives the wake-up frame from the transmitting node A without collision.
Thereafter, the receiving node C sets the receiving block 101 to the SLEEP mode until the arrival of RZtime, and transmits the ACK frame when the RZtime arrives, thereby receiving the data frame from the transmitting node A.

As described above, in this embodiment, when a receiving block receives a wakeup frame, the receiving block is set in the sleep mode until the timing specified in the wakeup frame so that no collision occurs, and specified in the wakeup frame. When the received timing arrives, the sleep mode of the reception block is canceled and the data frame is received.
For this reason, it is possible to avoid the occurrence of collision after receiving the wake-up frame without collision, so there is no need to distribute the transmission timing over a long period of time, achieving both low power consumption and real-time performance. The hidden terminal problem can be effectively solved.
Even if a collision occurs during carrier sense, reception of the wakeup frame is continued until the collision is resolved, and only the wakeup frame is received from the node that continues to transmit until the end. Therefore, it is not necessary to distribute the transmission timing over the network, and it is possible to effectively solve the hidden terminal problem by realizing both low power consumption and real-time performance.

As described above, in the present embodiment,
A wireless communication device having an intermittent reception function and a wireless reception block that performs detection processing of a wireless signal at a fixed period, performs reception processing when receiving detection, and receives a wakeup frame for waking up the reception device It has a reception function to wake up when
When receiving a wakeup frame, if a collision is expected to occur, continue the reception, and when the collision is resolved, a wireless communication device that receives the wakeup frame and a wireless reception block explained.

In the present embodiment,
A wireless communication device that executes a wakeup sequence and transmits a wakeup frame continuously for a certain period of time when a communication request occurs, and a wireless transmission block,
A description has been given of a wireless communication device and a wireless transmission block that change transmission timing in units of wakeup frame lengths using random numbers during transmission.

In the present embodiment,
When a communication request occurs, a wireless communication device that executes a wake-up sequence in accordance with the timing at which the reception-side wireless communication device performs detection processing, and a wireless transmission block,
The wireless communication device and the wireless transmission block that extend the wake-up sequence using random numbers have been described.

In the present embodiment,
A wireless communication device that transmits an acknowledge frame indicating that communication data may be transmitted to the wireless communication device that transmitted the wakeup frame when the wakeup frame is received;
A wireless communication system configured by a wireless communication device that transmits communication data when an acknowledge frame is received has been described.

  In the present embodiment, the wireless communication device that returns to the intermittent reception operation again after the communication is completed has been described.

Embodiment 2. FIG.
In the first embodiment, the method of performing data communication with one of the transmission nodes when a collision due to the hidden terminal problem occurs in the wake-up sequence has been described, but in this embodiment, the communication with one of the nodes is described. A method of performing data communication with the other node without retrying the wake-up sequence after performing data communication will be described.

The configuration of radio communication apparatus 100 according to the present embodiment is the same as that shown in FIG.
However, in the present embodiment, the upper layer processing block 105 receives the wakeup frame, issues a reception activation request to the reception block 101 in RZtime, receives the data frame from the communication partner node, and then receives the communication request. The presence / absence check is performed on its own peripheral nodes.
That is, when the reception block 101 completes reception of the data frame, the upper layer processing block 105 according to the present embodiment inquires of the node device other than the node device that transmitted the data frame whether the data frame needs to be transmitted. A communication request confirmation frame is transmitted from the transmission block 102.
The transmission block 102 broadcasts a communication request confirmation frame in the normal transmission mode.
Further, the upper layer processing block 105 maintains the reception block 101 in the reception mode state, and receives a response frame for the communication request confirmation frame.
When there is no response to the communication request confirmation frame, the upper layer processing block 105 issues a SLEEP request to the reception block 101.
When there is a response to the communication request confirmation frame, the upper layer processing block 105 causes the transmission block 102 to transmit a communication permission frame that permits transmission of the data frame to the node that has responded.

On the other hand, after the wake-up sequence is performed, the transmission side node continues reception for a certain period even if the ACK frame cannot be received (no SLEEP request is made to the reception block 101).
If the communication request confirmation frame is received while the reception is continued, the upper layer processing block 105 transmits a response frame to the communication request confirmation frame from the transmission block 102, and receives a communication permission frame, transmits a data frame from the transmission block 102. To do.

When the two transmitting nodes start transmitting the wake-up sequence at exactly the same timing and end, the communication request confirmation is not transmitted from the receiving node.
For this reason, the transmitting node continues to receive for a certain period of time, and when the communication request confirmation frame cannot be received, performs a retry of the wakeup sequence.

  In addition, instead of the above, when reception of the wakeup frame is not possible due to a factor that seems to be a collision, the reception block 101 outputs collision detection at the receiving side node, and collision detection is output. The higher layer processing block 105 may transmit a communication request confirmation frame.

As described above, in the present embodiment,
After communication is completed, before returning to the intermittent reception operation, check with other communication devices whether there is a communication request.If there is no communication request, return to the intermittent operation. Giving communication permission to the communication device, and the wireless communication device that continues to receive,
If the acknowledge frame is not received as a result of the wake-up sequence, the receiving operation is continued, and when confirming the presence or absence of the communication request, the communication request is notified and the communication permission is granted. A wireless communication device that transmits communication data when given is described.

Embodiment 3 FIG.
By assigning priorities to frames, it is possible to enhance real-time performance.
Therefore, it is possible to preferentially transmit / receive by increasing the added amount of the wake-up sequence in FIG. 3 as the frame with higher priority.
In other words, in the present embodiment, the upper layer processing block 105, for example, wakes up frames that the transmission block 102 continuously transmits so that the number of wakeup frames increases as the priority of the actual data transmitted in the data frame increases. Determine the number of.
Then, the transmission block 102 continuously transmits the number of wake-up frames determined by the upper layer processing block 105.
Note that when the upper layer processing block 105 outputs a wakeup frame, the priority is also output at the same time.
The priority is determined in advance by the system depending on the attribute of actual data, the status of the system or node, the frame type, and the like.

As described above, in the present embodiment,
A wireless communication apparatus has been described in which a wake-up sequence to be extended is set longer depending on the priority level.

  In this specification, the wireless communication device is described as an example. However, the application target is not limited to the wireless communication device, and the above-described content can be applied to a wired communication device.

Finally, a hardware configuration example of the wireless communication apparatus 100 shown in the first to third embodiments will be described.
FIG. 14 is a diagram illustrating an example of hardware resources of the wireless communication device 100 illustrated in the first to third embodiments.
Note that the configuration of FIG. 14 is merely an example of the hardware configuration of the wireless communication device 100, and the hardware configuration of the wireless communication device 100 is not limited to the configuration illustrated in FIG. Also good.

In FIG. 14, the wireless communication apparatus 100 includes a CPU 911 (also referred to as a central processing unit, a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, and a processor) that executes a program.
The CPU 911 is connected to, for example, a ROM (Read Only Memory) 913, a RAM (Random Access Memory) 914, a communication board 915, a display device 901, a keyboard 902, a mouse 903, and a magnetic disk device 920 via a bus 912. Control hardware devices.
Further, the CPU 911 may be connected to an FDD 904 (Flexible Disk Drive) or a compact disk device 905 (CDD).
In addition to these hardware devices, the wireless communication apparatus 100 may include a non-contact IC (Integrated Circuit) card, a camera, a vibrator, an acceleration sensor, and the like.
Further, instead of the magnetic disk device 920, a storage device such as an SSD (Solid State Drive), an optical disk device, or a memory card (registered trademark) read / write device may be used.
The RAM 914 is an example of a volatile memory. The storage media of the ROM 913, the FDD 904, the CDD 905, and the magnetic disk device 920 are an example of a nonvolatile memory. These are examples of the storage device.
The communication board 915, the keyboard 902, the mouse 903, the FDD 904, and the like are examples of input devices.
The communication board 915, the display device 901, and the like are examples of output devices.

For example, the communication board 915 may have an interface corresponding to wireless LAN (local area network), infrared communication, etc. in addition to public wireless network communication.
It is also possible to connect to the Internet, a WAN (wide area network), a SAN (storage area network), etc. via public wireless network communication, a wireless LAN, or the like.

The magnetic disk device 920 stores an operating system 921 (OS), a window system 922, a program group 923, and a file group 924.
The programs in the program group 923 are executed by the CPU 911 using the operating system 921 and the window system 922.

The RAM 914 temporarily stores at least part of the operating system 921 program and application programs to be executed by the CPU 911.
The RAM 914 stores various data necessary for processing by the CPU 911.

The ROM 913 stores a BIOS (Basic Input Output System) program, and the magnetic disk device 920 stores a boot program.
When the wireless communication device 100 is activated, the BIOS program in the ROM 913 and the boot program in the magnetic disk device 920 are executed, and the operating system 921 is activated by the BIOS program and the boot program.

  The program group 923 stores programs that execute the functions described as “˜block” and “˜unit” in the description of the first to third embodiments. The program is read and executed by the CPU 911.

In the file group 924, in the description of the first to third embodiments, “determination of”, “adjustment of”, “detection of”, “comparison of”, “update of”, and “setting of” are set. ”,“ Registration of ”,“ Selection of ”, etc. Information, data, signal values, variable values, and parameters indicating the results of the processing are indicated as“ ˜file ”and“ ˜database ”items. It is remembered.
The “˜file” and “˜database” are stored in a recording medium such as a disk or a memory.
Information, data, signal values, variable values, and parameters stored in a storage medium such as a disk or memory are read out to the main memory or cache memory by the CPU 911 via a read / write circuit.
The read information, data, signal value, variable value, and parameter are used for CPU operations such as extraction, search, reference, comparison, calculation, calculation, processing, editing, output, printing, and display.
Information, data, signal values, variable values, and parameters are stored in the main memory, registers, cache memory, and buffers during the CPU operations of extraction, search, reference, comparison, calculation, processing, editing, output, printing, and display. It is temporarily stored in a memory or the like.
In addition, the arrows in the flowcharts described in Embodiments 1 to 3 mainly indicate input and output of data and signals.
Data and signal values are recorded on a recording medium such as a memory of the RAM 914, a flexible disk of the FDD 904, a compact disk of the CDD 905, a magnetic disk of the magnetic disk device 920, other optical disks, a mini disk, and a DVD.
Data and signals are transmitted online via a bus 912, signal lines, cables, or other transmission media.

In addition, what is described as “˜block” and “˜unit” in the description of the first to third embodiments may be “˜circuit”, “˜device”, and “˜device”. It may be “˜step”, “˜procedure”, “˜processing”.
That is, the communication method according to the present invention can be realized by the steps, procedures, and processes shown in the flowcharts described in the first to third embodiments.
In addition, what is described as “˜block” and “˜unit” may be realized by firmware stored in the ROM 913.
Alternatively, it may be implemented only by software, or only by hardware such as elements, devices, substrates, and wirings, by a combination of software and hardware, or by a combination of firmware.
Firmware and software are stored as programs in a recording medium such as a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, and a DVD.
The program is read by the CPU 911 and executed by the CPU 911.
That is, the program causes the computer to function as “to block” and “to part” in the first to third embodiments. Alternatively, the procedures and methods of “˜block” and “˜unit” in the first to third embodiments are executed by a computer.

As described above, the wireless communication device 100 described in the first to third embodiments includes a CPU that is a processing device, a memory that is a storage device, a magnetic disk, a keyboard that is an input device, a mouse, a communication board, and a display device that is an output device and a communication device. A computer including a board or the like.
As described above, the functions indicated as “˜block” and “˜unit” are realized by using these processing devices, storage devices, input devices, and output devices.

  100 wireless communication device, 101 reception block, 102 transmission block, 103 switch, 104 intermittent operation control block, 105 upper layer processing block.

Claims (16)

A carrier sense timing detector that detects the arrival of the carrier sense timing that arrives intermittently and notifies the arrival of the carrier sense timing;
It operates in the sleep mode in which carrier sense processing and communication frame reception are not performed until the arrival of the carrier sense timing is notified, and the sleep mode is canceled when the arrival of the carrier sense timing is notified from the carrier sense timing detection unit. A carrier sense process, and a reception unit that starts receiving a communication frame when a radio wave of a predetermined level or more is detected in the carrier sense process;
A transmission unit for transmitting a predetermined acknowledge frame;
When the receiver receives a wake-up frame without a collision, which is a communication frame prior to a data frame including actual data and addressed to the own device in which the transmission timing of the acknowledge frame is designated after carrier sensing processing. A communication that is a transmission source of the wakeup frame as a response to the wakeup frame when the reception unit shifts to a sleep mode and the transmission timing specified by the wakeup frame received by the reception unit without collision has arrived An acknowledge frame permitting a destination device to transmit a data frame is transmitted from the transmission unit to the communication destination device, and a sleep mode of the reception unit is canceled to cause the reception unit to receive a data frame from the communication destination device. A communication control unit. Communication apparatus according to claim. The communication control unit
When the receiving unit detects radio waves from two or more devices during the carrier sense process of the receiving unit and a collision occurs, the receiving unit starts receiving a wake-up frame, and only one device Since the transmission of the wakeup frame is continued and another device has finished transmitting the wakeup frame, the reception unit shifts to the sleep mode when the reception unit receives the wakeup frame from the one device without collision. The communication apparatus according to claim 1. The communication control unit
After the receiving unit receives the wakeup frame from one device without collision, the wakeup frame is transmitted from the other device, and the wakeup frame is continuously transmitted from the other device even at the transmission timing of the acknowledge frame. 3. The communication device according to claim 1, wherein after the transmission of the wake-up frame from the other device is completed, the transmission unit causes the one device to transmit an acknowledge frame. 4. . The communication control unit
4. The receiver according to claim 1, wherein the receiver is shifted to a sleep mode when the receiver receives one of a plurality of continuously transmitted wakeup frames without collision. 5. Communication device. The communication control unit
The communication apparatus according to claim 1, wherein when the reception unit completes reception of a data frame, the reception unit is shifted to a sleep mode. The communication control unit
When the receiving unit completes reception of the data frame,
A communication request confirmation frame for inquiring whether a data frame needs to be transmitted to a device other than the communication destination device is transmitted from the transmission unit,
The communication apparatus according to claim 1, wherein the reception unit is maintained in a state in which a communication frame can be received, and a response frame with respect to the communication request confirmation frame is received. The communication control unit
When the reception unit receives a response frame to the communication request confirmation frame, the transmission source device of the response frame transmits a communication permission frame that permits transmission of a data frame from the transmission unit,
The communication device according to claim 6, wherein the receiving unit receives a data frame from a device that is a transmission source of the response frame. A communication device that transmits a data frame including actual data to a communication destination device that intermittently performs carrier sense,
Prior to transmission of the data frame, a communication control unit for instructing transmission of a wakeup frame that specifies transmission timing of an acknowledge frame to be transmitted when the communication destination device permits transmission of the data frame;
Based on an instruction from the communication control unit, a plurality of wakeup frames are continuously transmitted to the communication destination device, and a data frame is transmitted to the communication destination device when an acknowledge frame is received from the communication destination device. A transmission unit for transmitting
A communication device comprising: a receiving unit that receives an acknowledge frame transmitted from the communication destination device after the transmission timing as a response to the wakeup frame. The communication control unit
Determining the number of wake-up frames that the transmitter continuously transmits so that the number of wake-up frames increases as the priority of the actual data transmitted in the data frame increases;
The transmitter is
9. The communication apparatus according to claim 8, wherein the number of wake-up frames determined by the communication control unit is continuously transmitted. The communication control unit
The random number is used to determine the number of wakeup frames continuously transmitted by the transmission unit, and the communication destination device is instructed to transmit the determined number of wakeup frames according to the timing at which carrier sense is performed. ,
The transmitter is
The communication device according to claim 8 or 9, wherein the number of wake-up frames determined by the communication control unit is continuously transmitted at a timing instructed by the communication control unit. The communication control unit
When the timing at which the communication destination device performs carrier sense is unknown, the transmission timing of the wakeup frame is determined using a random number, and the transmission unit is instructed to transmit the wakeup frame at the determined transmission timing.
The transmitter is
The communication apparatus according to claim 8, wherein a predetermined number of wake-up frames are continuously transmitted at a timing instructed by the communication control unit. The receiver is
When not receiving an acknowledge frame from the communication destination device, a communication request confirmation frame that inquires whether transmission of a data frame is necessary may be received from the communication destination device.
The communication control unit
When the reception unit receives a communication request confirmation frame, the transmission unit transmits a response frame to the communication request confirmation frame from the transmission unit to the communication destination device, and after the transmission of the response frame by the transmission unit, the reception unit The communication apparatus according to claim 8, wherein when a communication permission frame is received from the apparatus, a data frame is transmitted from the transmission unit to the communication destination apparatus. A carrier sense timing detecting step in which the computer detects the arrival of intermittently coming carrier sense timing;
The computer maintains a sleep mode in which carrier sense processing and communication frame reception are not performed until the arrival of carrier sense timing is detected, and when the arrival of carrier sense timing is detected in the carrier sense timing detection step, the sleep mode is detected. To start carrier sense processing, start receiving a communication frame when detecting a radio wave of a predetermined level or higher in carrier sense processing,
A transmitting step in which the computer transmits a predetermined acknowledge frame;
After carrier sense processing in the receiving step, the computer uses the receiving step to establish a wake-up frame addressed to the computer that is a communication frame preceding the data frame including actual data and for which the transmission timing of the acknowledge frame is specified. When the transmission timing specified by the wake-up frame received without collision arrives, the computer transmits the wake-up frame as a response to the wake-up frame. An acknowledge frame that permits transmission of a data frame to the original communication destination device is transmitted to the communication destination device by the transmission step, sleep mode is canceled, and the communication step is performed by the reception step. Communication method characterized by having a communication control step of receiving the data frame from the previous device. A communication method performed by a computer that transmits a data frame including actual data to a communication destination device that intermittently performs carrier sense,
Prior to transmission of a data frame, the computer instructs the transmission of a wakeup frame for designating transmission timing of an acknowledge frame to be transmitted when the communication destination device permits transmission of the data frame; and
The computer continuously transmits a plurality of wake-up frames to the communication destination device based on an instruction of the communication control step, and receives an acknowledge frame from the communication destination device. Transmitting a data frame and
And a receiving step of receiving an acknowledge frame transmitted from the communication destination device after the transmission timing as a response to the wake-up frame. On the computer,
A carrier sense timing detection step for detecting the arrival of intermittently coming carrier sense timing;
Until the arrival of the carrier sense timing is detected, the sleep mode in which the carrier sense processing and the reception of the communication frame are not performed is maintained, and when the arrival of the carrier sense timing is detected from the carrier sense timing detection step, the sleep mode is canceled. A reception step of starting carrier sense processing and starting reception of a communication frame when radio waves of a predetermined level or higher are detected in carrier sense processing;
A transmission step of transmitting a predetermined acknowledge frame;
After receiving the wake-up frame addressed to the computer, which is a communication frame preceding the data frame including the actual data and the transmission timing of the acknowledge frame is specified after the carrier sense process in the reception step, without collision, When the transmission timing specified by the wakeup frame that has been received without collision has entered the sleep mode, a data frame is transmitted to the communication destination device that is the transmission source of the wakeup frame as a response to the wakeup frame real and communication control step of receiving a data frame from the communication destination device by the reception step to cancel the sleep mode and transmits an acknowledge frame to the communication destination device by the transmitting step to allow Program characterized thereby. For a communication destination device that intermittently performs carrier sense, to a computer that transmits a data frame containing actual data,
Prior to transmission of the data frame, a communication control step for instructing transmission of a wakeup frame that specifies transmission timing of an acknowledge frame to be transmitted when the communication destination device permits transmission of the data frame;
Based on the instruction of the communication control step, a plurality of wakeup frames are continuously transmitted to the communication destination device, and when an acknowledge frame is received from the communication destination device, a data frame is transmitted to the communication destination device. A sending step to send;
And a receiving step of receiving an acknowledge frame transmitted from the communication destination device after the transmission timing as a response to the wakeup frame.

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