JP5338707B2 - Wireless communication apparatus and wireless communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid the exclusive usage of radio wave by short carrier sense radio communication equipment without sacrificing power saving property by the short carrier sense. <P>SOLUTION: The radio communication equipment of a first network where a carrier sense time is shorter than a carrier sense time regulated in a second network with the same band to be used for radio communication, includes: a means for outputting an average transmission data length; a means for outputting the number of peripheral devices; and a means for determining a time as a halt time, which is longer by at least the carrier sense time of the second network than a time to be taken in a case if radio communication equipment belonging to the first network with the number of peripheral devices successively transmits data of the average transmission data length after data are transmitted from the radio communication equipment, and then, setting the determined halt time. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a radio communication device and a radio communication system, and can be applied to, for example, a radio communication device and a radio communication system having a function of avoiding interference of radio waves from a plurality of radio communication devices.

  When performing wireless communication, if transmission is started when other radio waves exist, radio wave interference occurs and communication cannot be performed correctly. In order to avoid this radio wave interference, an interference avoidance function for performing transmission after confirming that other radio communication devices or the like are not using radio waves has become widespread. In particular, an interference avoidance function is indispensable in a band that permits sharing of a plurality of wireless communication apparatuses having different purposes, such as a 950 MHz band and a 2.4 GHz band.

  There are various interference avoidance functions, but the simplest is to sense that there is no carrier (= radio wave or noise) stronger than a certain threshold before transmission for a certain period of time (= There is a so-called “carrier sense” which is transmitted when it is detected.

  In general, the time for sensing a carrier is designed in accordance with the characteristics of the wireless communication device and the surrounding conditions. When a short communication ends, a short time carrier sense is performed, and when a long communication is performed, a slightly long carrier sense is often performed.

  As in the 950 MHz band, carrier sense time may be determined by law. FIG. 2 is an explanatory diagram showing carrier sense conditions (transmission power of 10 mW or less) in the 950 MHz band law. For example, in the case of a passive tag reader / writer that communicates for a long time of several hundred milliseconds to several seconds, it is specified that a transmission output exceeding 10 mW performs carrier sense for 5 milliseconds or more and 10 mW or less for 10 milliseconds or more. Has been. On the other hand, an active wireless communication device that performs short packet communication of several milliseconds to several tens of milliseconds works technically even with a short carrier sense, but in consideration of sharing with passive devices, the basics Specifically, it is determined that carrier sense of 10 milliseconds or more is performed.

  This carrier sense length of 10 milliseconds is large compared to the length of data, and when designing to reduce the power consumption of the device, or quickly responding to data from other wireless communication devices. It becomes a big obstacle when doing. In IEEE802.15.4 (Non-patent Document 1), which is a standard for wireless communication for the purpose of low transmission output and low power consumption, carrier sense of about 100 microseconds is defined (exactly in the transmission rate). (In the case of a transmission rate of 100 kbit / s, it is 80 microseconds). Therefore, even in the 950 MHz band law, as shown in FIG. 2, if the transmission output of 1 mW or less is very low, the upper limit is set on the length of the continuous transmission time and the sum of the transmission time, so that it is 128 microseconds or more Operation with a short carrier sense is permitted. As of December 2009, amendments to laws and regulations are under discussion. In the future, this special case of short carrier sense is expected to be applied to devices of 10 mW or less (Non-Patent Document 2), and short carrier sense is used. It is predicted that the number of wireless communication devices will increase.

IEEE802.15.4-2003 Ministry of Internal Affairs and Communications November 13, 2009 Press Release "Recruitment of Opinions for Power Saving Wireless System Committee Report (Draft)" (http://www.soumu.go.jp/menu_news/s-news/21291.html) Attachment report (draft)

  As described above, according to the 950 MHz band law, a wireless communication device with a long carrier sense (5 milliseconds or 10 milliseconds) and a wireless communication device with a short carrier sense (128 microseconds) coexist. As shown in FIG. 3, when there is one long carrier sense and one short carrier sense wireless communication device, there is a timing at which communication with the partner device is not completed and carrier sense fails and transmission is not possible. After communication with the partner device is completed, the carrier sense is always successful because it pauses for 100 milliseconds regardless of whether the partner device is a long carrier sense wireless communication device or a short carrier sense wireless communication device. It is possible to start communication.

  However, when there are a plurality of short carrier sense wireless communication devices, as shown in FIG. 4, a plurality of short carrier sense wireless communication devices transmit one after another, and a long carrier sense wireless communication device transmits forever. Things that cannot be done may occur. Actually, since the end of transmission of other wireless communication devices is not mutually monitored, there is a slight time lag between the end of transmission of another wireless communication device and the start of carrier sense. However, the time lag is omitted in FIG.

  As shown in FIG. 2, the short carrier sense wireless communication device is limited to a total transmission time ratio of 10% or less, and thus is unlikely to be occupied continuously for many scenes. However, for example, when there are 10 or more short-carrier-sense wireless communication devices and each performs transmission near the upper limit of 10% of the total transmission time, there is a possibility of permanently occupying radio waves. There is. Further, for example, in the case of a wireless communication apparatus with a total transmission time ratio of 5%, radio waves may be occupied by 20 or more devices.

  Therefore, a mechanism for preventing radio waves from being occupied by a short carrier sense wireless communication device is required.

  In order to solve this problem, a function called back-off that delays the transmission time at random can be used. The original purpose of the random backoff function is to force a random delay before carrier sense to prevent radio interference by sending out radio waves at the same time when simultaneously trying to transmit, and simultaneously sending out radio waves. The delay of insertion is generally 1 millisecond or less at the maximum. In the above-described problem, it is only necessary to enable a 10 ms long carrier sense wireless communication device to transmit, so as shown in FIG. 5, the short carrier sense wireless communication device has a maximum value of 10 milliseconds or more. If the random backoff is inserted, the above-described problem can be solved. However, there is a communication standard that includes random backoff in the carrier sense time and counts before the other party's communication ends. In this case, transmission can be performed immediately, and the above-described problems cannot be solved. Here, as in IEEE802.15.4, it has been explained that the problem can be solved on the premise of random backoff in which a random delay is inserted after the other party's communication ends.

  This solution by random back-off is a good solution from the viewpoint of equality of communication opportunities, but adds an extra delay to a short-carrier-sense wireless communication device, making it impossible to transmit quickly. In the first place, the main purpose of introducing short carrier sense was to reduce power consumption, but by inserting a short delay with random backoff, the operation time of each unit (for example, CPU) of the wireless communication device is reduced. The power saving effect is lost. In other words, the introduction of random backoff makes the power consumption the same as in the case of long carrier sense, and the meaning of introducing short carrier sense is lost.

  Therefore, there is a need for a wireless communication device and a wireless communication system capable of avoiding the short carrier sense wireless communication device from exclusively using radio waves without sacrificing the power saving performance due to the short carrier sense.

In order to solve such a problem, according to the first aspect of the present invention, the carrier sense time is shorter than the carrier sense time defined in the second network having the same band used for wireless communication. In a short carrier sense wireless communication apparatus belonging to a network, (1) grasping a pause time determination data length for outputting information of a pause time determination data length used to determine a pause time during which the radio communication apparatus pauses after data transmission Means, (2) peripheral device number grasping means for outputting information on the number of peripheral devices used for determining the suspension time, and (3) the suspension time determination data length output from the suspension time determination data length grasping means. information and the output from the peripheral device number detection means peripheral device number information, based on the carrier sense time according to the first network, the When it is assumed that after the data transmission from the line communication device, the wireless communication devices belonging to the first network of the number indicated by the peripheral device number information successively transmit the data of the pause time determination data length And a pause time giving means for determining a pause time that is at least longer than the carrier sense time defined in the second network as the pause time and setting the decided pause time.

  The wireless communication system of the second aspect of the present invention performs wireless communication between the wireless communication apparatuses of the first aspect of the present invention.

  According to the present invention, it is possible to prevent a short carrier sense wireless communication apparatus from occupying a radio wave without adding an extra delay, and to reduce power consumption.

It is a block diagram which shows the functional structure of the radio | wireless communication apparatus which concerns on 1st Embodiment. It is explanatory drawing which shows the carrier sense conditions (transmission power of 10 mW or less) in 950 MHz band regulations. It is explanatory drawing which shows the example of coexistence of the long carrier sense and short carrier sense in a 950 MHz band. It is explanatory drawing of the subject that the some radio | wireless communication apparatus of a short carrier sense occupies an electromagnetic wave. It is explanatory drawing of the possible mechanism (random backoff) which prevents a radio wave from being occupied by the radio | wireless communication apparatus of a short carrier sense. 4 is a timing chart illustrating a state in which a long carrier sense device has acquired a transmission right in the wireless communication system according to the first embodiment. It is a block diagram which shows the functional structure of the radio | wireless communication apparatus which concerns on 2nd Embodiment.

(A) First Embodiment Hereinafter, a first embodiment of a wireless communication apparatus and a wireless communication system according to the present invention will be described with reference to the drawings.

  The wireless communication system according to the first embodiment has a communication band that allows sharing of a plurality of wireless communication apparatuses with different purposes, such as a 950 MHz band and a 2.4 GHz band. The wireless communication device is a constituent element. The wireless communication device of the first embodiment as a constituent element is a short carrier sense device, and not only the wireless communication device of the same purpose (the wireless communication device of the first embodiment) but also its surroundings There may be a wireless communication device for other purposes that uses a band and has a long carrier sense.

  The wireless communication apparatus according to the first embodiment is characterized in that after data transmission from the wireless communication apparatus, the wireless communication apparatus pauses for a period corresponding to the number of peripheral wireless communication apparatuses.

(A-1) Configuration of First Embodiment FIG. 1 is a block diagram showing a functional configuration of a wireless communication apparatus 100 according to the first embodiment. In FIG. 1, the wireless communication device 100 includes an average transmission data length calculation unit 101, a peripheral device number grasping unit 102, a pause time control unit 103, a transmission unit 104, and a reception unit 105. Some of these components (for example, the average transmission data length calculation unit 101, the peripheral device number grasping unit 102, the suspension time control unit 103) realize the functions of the components by the CPU executing a program. There may be.

  The average transmission data length calculation unit 101 calculates the time taken to transmit the transmission data, and gives the past average value to the pause time control unit 103. Here, the average value may determine the number of times used for the average, such as the average for the past 10 times, and store the data transmission time for the number corresponding to the number. Further, the total data transmission time of the predetermined number minus one is stored, and when the latest data transmission time is given, the average value is calculated using the stored data transmission total time. good. Furthermore, after obtaining the average transmission data length, it may be converted into a transmission time to obtain an average value of the transmission data time.

  The peripheral device number grasping unit 102 determines the number of peripheral wireless communication devices that have an influence on radio wave interference from the received signal (this number may or may not include the wireless communication device. ) Is calculated and given to the pause time control unit 103. Here, when the number of units is simply calculated, it is only necessary to calculate the number of neighboring nodes in the network (wireless communication system) including the device itself, and the NeighborTable defined in IEEE 802.15.4 or the like. You can use the number of entries managed in. Here, the number of devices in other networks that do not include the wireless communication device (for example, a device with a long carrier sense) may be calculated so as to be included in the number. In this case, it is at the head of the packet. It is also possible to count only the opponents that have successfully decoded the preamble. In this way, it is possible to prevent mere noise from being included in the number.

  If the calculated number is equal to or less than the predetermined number, the peripheral device number grasping unit 102 may give predetermined information to the suspension time control unit 103 instead of the calculated number. For example, when the ratio of the total transmission time is set to 10% or less for each wireless communication device by law (see FIG. 2), the number of peripheral devices (including the wireless communication device) is 9 or less The peripheral device number grasping unit 102 passes information indicating that the number of peripheral devices is zero or that there is no fear of permanent occupation to the suspension time control unit 103. This is because, in the case of nine or less units, there is no possibility that the short-carrier-sense wireless communication device described as a conventional problem is permanently occupied. Similarly, if the ratio of the total transmission time is set to 5% or less for each wireless communication device, if the number of peripheral devices (including the wireless communication device) is 19 or less, The number-of-devices grasping unit 102 passes information indicating that the number of peripheral devices is zero or that there is no fear of permanent occupation to the suspension time control unit 103.

  The pause time control unit 103 receives the transmission time of the average data length given from the average transmission data length calculation unit 101, the short carrier sense time determined for the network including the wireless communication device, and the peripheral device number grasping unit 102 Based on the given number of peripherals (or the number of peripherals −1), the idle time in which the short-carrier-sense wireless communication device does not permanently occupy radio waves is determined. For example, if the number of peripheral devices is the number that the short-carrier-sense wireless communication device does not occupy radio waves permanently, the pause time control unit 103 is the minimum pause time determined by laws and regulations (FIG. 2). If the number of peripheral devices is the number of short-carrier-sense wireless communication devices that may permanently occupy radio waves, the minimum number specified by laws and regulations is required. The pause time is defined as a time longer than the pause time and approximately proportional to the number of units, and including a free time during which the long carrier sense wireless communication apparatus can acquire the transmission right.

For example, the pause time control unit 103 is the minimum time of the carrier sense time (short carrier sense time) determined for the network including the wireless communication device in the transmission time of the average data length given from the average transmission data length calculation unit 101 (Hereinafter, this minimum time may be referred to as a short carrier sense time) is added, and the product of the value and the peripheral number -1 (or the peripheral number) received from the peripheral device number grasping unit 102 is calculated. In this product, the minimum time of the carrier sense time (long carrier sense period) in the long carrier sense radio communication apparatus (hereinafter, this minimum time may be referred to as the long carrier sense time; in the example of FIG. 2, 10 milliseconds) ) is the value obtained by adding, if less than the dwell time that definite the short carrier sense of the wireless communication device regulations, etc. (100 ms in the example of FIG. 2) is, downtime is definite with laws and regulations (100 (Milliseconds) is set as the pause time, and when the pause time is larger than the pause time determined by laws and regulations, the calculated value is given to the transmission unit 104 as the pause time.

Here, when the random backoff function is used, after adding the short carrier sense time and the average value (average time) of the random backoff to the transmission time of the average data length, Find the product. In addition, when information indicating that there is no fear of permanent occupation is given from the peripheral device number grasping unit 102, the downtime control unit 103 does not perform a calculation on the short-carrier-sense wireless communication device, the in and downtime definite in may be determined as the downtime to be given to the transmitting unit 104.

  The transmission unit 104 performs carrier sense for the specified short carrier sense time, and transmits data when data transmission / reception is not performed between other wireless communication devices in the vicinity. After data transmission, the transmission unit 104 pauses for the pause time given by the pause time control unit 103, and then starts the next data transmission operation starting from carrier sense.

  The receiving unit 105 receives a radio signal captured by the antenna and extracts received data. If the received data is data representing the number of peripheral devices, or the peripheral device number grasping unit 102 is data necessary for counting the number of peripheral devices, the receiving unit 105 This is given to the device number grasping unit 102.

(A-2) Operation of First Embodiment Next, operations of the wireless communication apparatus and the wireless communication system according to the first embodiment will be described.

  For example, it is assumed that the transmission time of the average data length of the wireless communication device according to the first embodiment is 80 milliseconds, the carrier sense time is 128 microseconds, and the number of peripheral devices is 13 including the own device. In this case, the pause time control unit 103 of the wireless communication apparatus calculates 971.536 milliseconds as the pause time as shown in the equation (1). Since the calculated pause time 971.536 milliseconds is longer than the prescribed pause time 100 milliseconds specified by laws and regulations, the calculated pause time 971.536 milliseconds is given to the transmission unit 104. The reason why 12 (= 13-1) units are applied in the equation (1) is because the idle time is a free time for another wireless communication apparatus to acquire the transmission right.

(80 milliseconds + 128 microseconds) x 12 units + 10 milliseconds = 971.536 milliseconds
... (1)
FIG. 6 shows a case where 12 out of 13 wireless communication devices have a short carrier sense, and the transmission times of the average data length of 12 wireless communication devices with a short carrier sense are the same. Assume that twelve short carrier sense wireless communication apparatuses have acquired transmission rights one after another. After the data transmission of the short carrier sense wireless communication device that first acquired the transmission right is completed (see FIG. 6B), other wireless communication devices of 11 short carrier senses acquire the transmission right one after another. (See FIGS. 6 (C), (D), (E), (F),...), Even if the short carrier sense wireless communication device that first acquired the transmission right attempts to start the second transmission operation, Since the time is 971.536 milliseconds and 10 milliseconds of the long carrier sense time is included, the time when the data transmission from the short carrier sense wireless communication apparatus which acquired the transmission right for the 12th time is completed The time point is 10 milliseconds or more before the pause time of the short carrier sense wireless communication device that first acquires the transmission right. That is, there is a time (free time) during which all short-carrier-sense wireless communication devices are idle, in other words, there is a time during which the short-carrier-sense wireless communication devices release radio waves. Therefore, as shown in FIG. 6A, a long carrier sense wireless communication apparatus can acquire a transmission right in the idle time.

  In the above description, the average data length (transmission time) of the 12 short carrier sense wireless communication apparatuses is the same. The average data lengths of the twelve short carrier sense wireless communication apparatuses are not necessarily the same. However, the purpose of data transmission from each wireless communication device (for example, collection of sensor information) is often the same depending on the application of the network and the like, and the average data length of 12 short carrier sense wireless communication devices (Transmission time) is often considered to be the same. Under such a premise, the wireless communication system according to the first embodiment attempts to form a time (vacant time) during which all short-carrier-sense wireless communication devices are idle.

  Also, for example, it is assumed that the transmission time of the average data length of the wireless communication device according to the first embodiment is 5 milliseconds, the carrier sense time is 128 microseconds, and the number of peripheral devices is 13 including the own device. . In this case, the pause time control unit 103 of the wireless communication apparatus calculates 71.536 milliseconds as the pause time as shown in Equation (2). Since the calculated pause time 71.536 milliseconds is shorter than the prescribed pause time 100 milliseconds specified by laws and regulations, the pause time control unit 103 uses the prescribed pause time 100 milliseconds specified by laws and regulations. Seconds are given to the transmission unit 104.

(10 milliseconds + 128 microseconds) x 12 units + 10 milliseconds = 71.536 milliseconds
... (2)
The calculated pause time 71.536 milliseconds includes 10 milliseconds of the long carrier sense time, and the pause time that the transmission unit 104 secures after data transmission is longer than the calculated 71.536 milliseconds. Since it is 100 milliseconds, even if the short-carrier-sense wireless communication devices successively acquire transmission rights, the time (free time) during which all short-carrier-sense wireless communication devices are idle is 10 milliseconds. Second + (100 milliseconds−71.536 milliseconds) = 38.404 milliseconds. With this time, the long-carrier-sense wireless communication apparatus can acquire the transmission right.

  Further, for example, it is assumed that the transmission time of the average data length of the wireless communication device according to the first embodiment is 80 milliseconds, the carrier sense time is 128 microseconds, and the number of peripheral devices is nine including the own device. . In this case, the peripheral device number grasping unit 102 of the wireless communication device reaches 100% as a whole even if the number of peripheral devices satisfies the total transmission limit of 10% for all short carrier sense wireless communication devices. No (= 80%) Since 9 units, 0 units are given to the pause time control unit 103. As a result, the pause time control unit 103 calculates 0 milliseconds as the pause time as shown in Equation (3). Since the calculated pause time of 0 milliseconds is shorter than the prescribed pause time of 100 milliseconds defined by laws and regulations, the pause time control unit 103 sets the prescribed pause time of 100 milliseconds specified by laws and regulations. This is given to the transmission unit 104.

(80 milliseconds + 128 microseconds) x 0 = 0 milliseconds (3)
When all short carrier sense wireless communication devices satisfy the legal maximum transmission total of 10%, transmission exceeding that limit cannot be performed. Therefore, 80% of the 100 millisecond pause time is all short carrier sense wireless communication devices. However, at least 20 milliseconds out of 100 milliseconds is a period of time during which all short-carrier-sense wireless communication devices are idle (free time). The wireless communication device can acquire a transmission right.

(A-3) Effect of First Embodiment According to the first embodiment, a short carrier sense wireless communication device occupies radio waves without adding an extra delay, and a long carrier sense wireless communication device It is possible to prevent a situation in which the transmission right cannot be acquired for a long time. Further, the conventional problem can be solved in at least one long rest period, and the power consumption can be suppressed as compared with the case where the carrier sense is performed many times with random backoff.

(B) Second Embodiment Next, the second embodiment of the present invention will be described with reference to the drawings.

  One of the features of the second embodiment is that the length of the pause time is controlled depending on the total transmission time.

(B-1) Configuration of Second Embodiment FIG. 7 is a block diagram showing a functional configuration of a wireless communication apparatus 200 according to the second embodiment, which is the same as FIG. 1 according to the first embodiment. Corresponding parts are denoted by the same reference numerals.

In FIG. 7, the wireless communication device 200 according to the second embodiment includes a transmission sum calculation unit 201, an average transmission data length calculation unit 101, a peripheral device number grasping unit 202, a pause time control unit 103, a transmission unit 104, and a reception unit 105. Have Here, the average transmission data length calculation unit 101, the pause time control unit 103, the transmission unit 104, and the reception unit 105 are the same as those in the first embodiment, and description of their functions is omitted.

  The transmission sum total calculation unit 201 obtains a ratio (duty ratio) of the total transmission time and gives it to the peripheral device number grasping unit 202. For example, the transmission sum total calculation unit 201 obtains the sum of the times when the wireless communication apparatus 200 transmits data every predetermined time (for example, one hour), and n thus obtained (n is an integer of 2 or more). The average of the total transmission times is obtained, the ratio of the average value of the transmission times to the predetermined time is obtained, and this is given to the peripheral device number grasping unit 202 as the ratio of the total transmission time.

  The peripheral device number grasping unit 202 of the second embodiment is different from the peripheral device number grasping unit 102 of the first embodiment in the following points. Peripheral device number grasping section 202 calculates the number of short carrier sense wireless communication apparatuses necessary to occupy radio waves based on the ratio of the total transmission time given from transmission total calculation section 201. The peripheral device number grasping unit 202 obtains the number of peripheral devices to be given to the suspension time control unit 103 by applying the calculated occupied number instead of the occupied number obtained from the provisions of laws and regulations. For example, if the ratio of the total transmission time is 10% (this 10% is equal to the upper limit of the law), the peripheral device number grasping unit 202 calculates the number necessary for occupation as 10 (= 100% / 10%) units. If it is 5%, the number required for occupation is calculated as 20 (= 100% / 5%). Similar to the first embodiment, if the number of peripheral devices including the wireless communication device is less than the calculated number of occupied devices, the peripheral device number grasping unit 202 notifies the suspension time control unit 103 of 0 or permanently. Passes information indicating that there is no fear of occupancy.

(B-2) Operation of Second Embodiment Next, operations of the wireless communication apparatus and the wireless communication system according to the second embodiment will be described.

  Unlike the wireless communication device 100 of the first embodiment, the wireless communication device 200 of the second embodiment determines the number of peripheral devices that a short carrier sense wireless communication device may occupy radio waves from laws and regulations. Instead, it is determined and applied according to the actual total transmission time.

  For example, in the case of the first embodiment, the transmission time of the average data length of the wireless communication device with short carrier sense is 80 milliseconds, the carrier sense time is 128 microseconds, and the number of peripheral devices includes its own device. Assuming that there are 13 units, as described above, the pause time control unit 103 of the wireless communication apparatus calculates 971.536 milliseconds as the pause time.

  In the second embodiment, it is determined whether or not it is necessary to make the pause time longer than that described in the law according to the calculated occupied number.

  For example, as described above, when the transmission time of the average data length of the wireless communication device with short carrier sense is 80 milliseconds, the carrier sense time is 128 microseconds, and the number of peripheral devices is 13 including the own device. If the ratio of the total transmission time is 5%, the number of occupied units will be 20 units, which is more than 13 units. Therefore, the addition of suspension time (addition means longer than the suspension time of the law) is unnecessary. Thus, the idle time in which the long-carrier-sense wireless communication apparatus can acquire the transmission right can be ensured with a pause of only 100 milliseconds as stipulated by law. In this case, the wireless communication device with short carrier sense has the following data with a pause time shorter than 871.536 milliseconds (= 971.536 milliseconds−100 milliseconds) compared to the case of the first embodiment. A transmission operation can be started.

  For example, as described above, the transmission time of the average data length of the wireless communication device with short carrier sense is 80 milliseconds, the carrier sense time is 128 microseconds, and the number of peripheral devices is 13 including the own device. In this case, if the ratio of the total transmission time is 8%, the number of occupied units (100% / 8% = 12.5, which is occupied by 13 units) is 13 units, which is the same as the number of peripheral devices. 971.536 milliseconds longer than the defined 100 milliseconds is set as a pause time, and a free time in which a long carrier sense wireless communication apparatus can acquire a transmission right is secured.

(B-3) Effects of the Second Embodiment According to the second embodiment, the same effects as those of the first embodiment can be obtained, and the following effects can also be obtained.

  In a wireless communication apparatus with a low ratio of the total transmission time, an unnecessary pause time (too long pause time) is not set, so that a power saving and low delay transmission operation can be performed.

(C) Other Embodiments In each of the above embodiments, the average transmission data length calculation unit 101 calculates the data length (or the transmission time) of transmission data in real time. However, the present invention is not limited to this. is not. For example, instead of calculating the data size every time, the maximum packet size (128 bytes in IEEE 802.15.4) may be simply applied, and the maximum continuous transmission length (100 (Millisecond) may be used as it is. In this case, the pause time after data transmission becomes longer than necessary, but the average transmission data length calculation unit 101 can be omitted, so that the overall power consumption can be reduced. The “pause time determination data length grasping means” in the claims includes not only the average transmission data length calculation unit 101 but also a configuration in the case of applying the fixed value of the data length described above.

  Further, even when the average transmission data length calculation unit 101 is left, the average of the calculated data length is not applied as it is, but it can be further guaranteed that the long carrier sense wireless communication apparatus can acquire the transmission right. In addition, a value obtained by adding a margin to the average of the calculated data length may be given to the pause time control unit 103.

  In each of the above embodiments, in the case where the number of peripheral devices is less than the occupied number, an example in which no additional time is provided for the downtime determined by laws and regulations is shown, but the present invention is not limited to this. . For example, the additional time may be set for the pause time without knowing the number of peripheral devices. The number of items may be provided as an initial setting item of the wireless communication device, and the installer or user may set the number of units, and always apply the set number of units to calculate the additional time of the downtime. In such a case, there is a possibility that the pause time after data transmission may become longer than necessary, but the peripheral device number grasping units 102 and 202 can be omitted, so that the overall power consumption can be reduced. The “peripheral device number grasping means” in the claims includes not only the peripheral device number grasping units 102 and 202 but also a configuration for realizing the setting described above.

  However, when both the data length and the number of data applied to the calculation of the downtime are fixed, the downtime is also fixed, and thus is excluded from the scope of the present invention. That is, a dynamically grasped value is applied to at least one of the data length and the number of units applied to the calculation of the downtime.

  Further, in each of the above embodiments, in a situation where there is a possibility of occupying radio waves with a short carrier sense wireless communication device, each peripheral device has a different pause time, but for each number range, A pause time may be determined. For example, 11 to 15 units may be set to the same downtime, and 16 to 20 units may be set to the same longer downtime. In this case, the rest time can be determined by applying a conversion table or the like without depending on the calculation. As the rest time stored in the table, for example, the rest time obtained by the above-described calculation method (see the formula (1)) may be stored by applying the maximum number of machines in the same range.

In each of the above embodiments, the device for grasping the number of peripheral devices without distinguishing between a long carrier sense device and a short carrier sense device is shown. The number of peripheral devices may be grasped in a distinguishing manner, and the downtime may be determined according to the grasped result. For example, the pause time control unit 103 adds the short carrier sense time determined for the network including the short carrier sense wireless communication device to the transmission time of the average data length given from the average transmission data length calculation unit 101, The product of the value and the number of short carrier sense peripheral devices received from the peripheral device number grasping units 102 and 202 is calculated, and this product is received from the long carrier sense period and the peripheral device number grasping units 102 and 202. Calculate the pause time by adding the product of the number of peripheral devices with long carrier sense, and if the calculated pause time is shorter than the pause time determined by laws and regulations for short carrier sense wireless communication devices, and downtime definite and are quiescent time (100 ms) or the like, was calculated if larger downtime that definite in laws and regulations holidays As downtime time, it suffices to provide to the transmitter 104. Further, as in the above-described modified embodiment, a conversion table that converts a combination of the number of peripheral devices with short carrier sense (or range thereof) and the number of peripheral devices with long carrier sense (or range thereof) into downtime is used. Then, the pause time may be determined.

  The description of each of the above embodiments has been made with the intention of a legal example of 950 MHz, but is not limited thereto. Even in other bands such as the 2.4 GHz band, systems having different carrier sense times are mixed, and the present invention can be applied when a short carrier sense device and a long carrier sense device coexist. Although the occupation of the radio communication device with short carrier sense has been described above, according to the present invention, it is also possible to prevent the occupation of the radio communication device without carrier sense. “Short carrier sense” in the claims includes “no carrier sense”.

  DESCRIPTION OF SYMBOLS 100, 200 ... Wireless communication apparatus, 101 ... Average transmission data length calculation part, 102, 202 ... Peripheral device number grasping part, 103 ... Pause time control part, 104 ... Transmission part, 105 ... Reception part, 201 ... Transmission sum total calculation part .

Claims (5)

In the short carrier sense wireless communication apparatus belonging to the first network, the carrier sense time belongs to the first network that is shorter than the carrier sense time defined in the second network that uses the same band for wireless communication.
Pause time determination data length grasping means for outputting information of pause time determination data length used to determine the pause time during which the wireless communication apparatus pauses after data transmission;
Peripheral device number grasping means for outputting peripheral device number information used for determining the pause time;
And information of the pause time determined data length detection means is output from the pause time determined for the data length, the output from the peripheral device number detection means peripheral device number information, carrier sense time according to the first network After the data transmission from the wireless communication device, the wireless communication devices belonging to the first network of the number indicated by the peripheral device number information transmit the data of the pause time determination data length one after another. A pause time giving means for determining a pause time that is at least as long as the carrier sense time defined in the second network, and setting the decided pause time. A wireless communication device. The peripheral device number grasping means dynamically grasps the number of other wireless communication devices located around the wireless communication device,
The suspension time providing means sets the suspension time defined for the first network as it is when the number of units output from the peripheral device number grasping means is equal to or less than the threshold number. Item 2. The wireless communication device according to Item 1. The data transmission time total time further comprises transmission time total ratio grasping means that captures the ratio of the total time regardless of transmission or non-transmission,
The wireless communication apparatus according to claim 2, wherein the pause time granting unit changes the size of the threshold number according to the ratio of the total time of data transmission time to the total time.   The wireless communication according to any one of claims 1 to 3, wherein the pause time determination data length grasping means outputs an average value of data lengths of data transmitted by acquiring a transmission right by carrier sense. apparatus.   A wireless communication system that performs wireless communication between the wireless communication apparatuses according to claim 1.

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