JP2004343245A - Method for starting wireless data communication and wireless data communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the power consumption of a slave unit in an unconnected state denoting that the slave unit is not connected to a master unit. <P>SOLUTION: At least one link channel is prepared to establish a wireless link between the slave unit and the master unit, the slave unit in an unconnected state broadcasts a connection request signal including the information of the slave unit and making a request connected to the master unit via one selected free link channel, awaits a connection request response signal including connection admission information transmitted from the master unit for receiving the connection request signal, and establishes the wireless link when the slave unit receives the connection request response signal within a prescribed time Taw after the transmission of the connection request signal. Further, when no free link channel is detected or no connection request response signal is received within the prescribed time Taw, the slave unit reaches a power-down state for a prescribed time Tpd wherein the power consumption level of the slave unit is lowered, and thereafter the slave unit restores from a power-down state to a free link channel selection state. The slave unit in the unconnected state denoting that the slave unit is not connected to the master unit accesses one or more link channels at random, then the probability of finding out the free link channel is increased and the time until the slave unit is connected to the link channel can considerably be reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a configuration in which wireless data communication is performed between a child device such as a portable information terminal that operates on battery power and a parent device such as a wireless LAN base station connected to a wired network such as a LAN. The present invention relates to a wireless data communication start method and a wireless data communication device for reducing power consumption of a slave unit that is not connected and is not connected.
[0002]
[Prior art]
It is necessary to suppress the consumption of the battery of a portable device such as a portable information terminal that operates on a battery power supply, and it is not preferable to keep the battery powered when not in use. However, in the case of a slave unit that is supposed to perform wireless communication with a master unit such as a wireless LAN base station, if the power is completely turned off, it takes a long time to start up the system when using it. Become. Therefore, many of such slave units are configured to be able to transition between a suspend state in which power consumption is low and a normal operation state in order to reduce the startup time.
[0003]
For example, the wireless terminal device described in Patent Literature 1 prepares a transmission / reception circuit for a narrow band wave operable at low power and a transmission / reception circuit for a wide band wave requiring high power, and transmits / receives a signal for a narrow band wave. Operate the circuit for normal calling, turn off the power of the transmitting / receiving circuit for wideband wave, and turn on the power of the transmitting / receiving circuit for wideband wave when the calling signal is detected by the transmitting / receiving circuit for narrowband wave. In this configuration, the power is turned off after the communication in the wide band is completed. This enables battery saving while suppressing power consumption by operating only a narrow-band wave receiving circuit corresponding to a call signal or the like during standby.
[0004]
[Patent Document 1]
JP 2002-135203 A
[0005]
[Problems to be solved by the invention]
In the wireless terminal device described in Patent Literature 1, power consumption is reduced by a configuration in which a power supply of a transmission / reception circuit for wideband waves used for normal data communication is turned off during standby. However, a slave unit that is not connected to the master unit and that is not connected (during standby) detects that the slave unit has entered the communication service area and responds to a call signal or the like until the connection with the master unit is completed. It is necessary to keep the receiving circuit for the narrow band wave operating at all times. That is, the slave unit in the unconnected state consumes power in the transmission / reception circuit for the narrowband wave even though it is not performing communication, and the consumption of the battery power is inevitable.
[0006]
An object of the present invention is to provide a wireless data communication starting method and a wireless data communication device that can reduce power consumption of a slave unit that is not connected to a master unit and is not connected.
[0007]
[Means for Solving the Problems]
In the wireless data communication start method according to the first aspect, at least one link channel for establishing a wireless link between the slave unit and the master unit is provided, and the unconnected slave unit is provided. One of the vacant link channels on which wireless communication is not performed is selected from the link channels, and a connection request signal that includes information about the child device and requests connection to the parent device is transmitted via the selected vacant link channel. When the connection request response signal including the connection permission information transmitted from the master unit that has received the connection request signal is transmitted by broadcasting, and the connection request response signal is received within a predetermined time Taw from the transmission of the connection request signal, When a wireless link is established and a free link channel is not detected, or when a connection request response signal is not received within a predetermined time Taw, a child is transmitted only for a predetermined time Tpd. It enters the power-down state for reducing the power consumption level, and wherein the return to the selection of a free link channel and thereafter returning from the power down state.
[0008]
Here, the procedure for selecting one of the free link channels is to randomly select one link channel from the prepared link channels, perform carrier sense on the selected link channel, and perform wireless communication. If not, the link channel is selected, and if wireless communication is being performed, the link channel is shifted to a power down state (claim 2).
[0009]
In addition, the procedure of selecting one of the free link channels is such that carrier sense is sequentially performed on prepared link channels, and when a free link channel is detected, the link channel is selected, and wireless communication is performed on all link channels. Is performed, the state transits to the power down state (claim 3).
[0010]
Further, the slave unit has information on the frequency of use of the prepared link channel, and the procedure of selecting one of the available link channels is performed in the order from the link channel with the lowest frequency of use for the prepared link channel. Sense is performed, and when a free link channel is detected, the link channel is selected, and when wireless communication is being performed on all link channels, a transition is made to a power down state (claim 4).
[0011]
In addition, the procedure of selecting one of the free link channels is such that carrier sense is sequentially performed on prepared link channels, and when a free link channel is detected, the link channel is stored, and carrier sense of all link channels is performed. After that, any one link channel is selected from the idle link channels, and a transition is made to the power-down state when wireless communication is being performed on all link channels (claim 5).
[0012]
Further, each time the slave unit shifts to the power down state, the slave unit randomly determines the power down state time Tpd within a range of a predetermined minimum time Tpdmin and a predetermined maximum time Tpdmax (Tpdmax> Tpdmin). ).
[0013]
The wireless data communication device according to claim 7, wherein at least one link channel for establishing a wireless link between the slave unit and the master unit is provided, and the slave unit is provided when the slave unit is not connected. Link channel selecting means for selecting one of the vacant link channels in which wireless communication is not performed from the link channels being used, and connection to the parent device through the selected vacant link channel, including the information of the child device. Broadcast request, and waits for a connection request response signal including connection permission information transmitted from the parent device in response to the connection request signal, and within a predetermined time Taw from the transmission of the connection request signal. A wireless link establishing means for establishing a wireless link when a response signal is received, and a wireless link establishment means for detecting no free link channel or a wireless link If a connection request response signal is not received within a predetermined time Taw by the link establishing means, the power down state is set to reduce the power consumption level of the slave unit for a predetermined time Tpd. Power down control means for returning to the processing of the link channel selection means.
[0014]
Here, the link channel selecting means randomly selects one link channel from the prepared link channels, performs carrier sense on the selected link channel, and, when wireless communication is not performed, the link channel. The channel is transmitted to the wireless link establishing means (claim 8).
[0015]
Further, the link channel selecting means is configured to sequentially perform carrier sense on the prepared link channels, and to transmit the link channel to the wireless link establishing means when detecting a free link channel (claim 9).
[0016]
Further, the slave unit has information on the frequency of use of the prepared link channel, and the link channel selecting means performs carrier sense on the prepared link channel in order from the link channel with the lowest frequency of use, and provides an idle link. When a channel is detected, the link channel is sent to the wireless link establishing means (claim 10).
[0017]
Further, the link channel selecting means performs carrier sense for the prepared link channels in order, stores the link channel when detecting an empty link channel, performs carrier sense for all link channels, and then performs an empty link In this configuration, any one link channel is selected from the channels and sent to the wireless link establishing means.
[0018]
Further, the power-down control means randomly determines the power-down state time Tpd within a range of a predetermined minimum time Tpdmin and a predetermined maximum time Tpdmax (Tpdmax> Tpdmin) every time the power-down state is entered. There is (claim 12).
[0019]
Further, the slave unit includes a transmission / reception circuit for transmitting / receiving a radio wave to / from the master unit, and when a power-down signal is output from the power-down control unit, the transmission / reception circuit is stopped to reduce power consumption. (Claim 13).
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
(Example of configuration of slave unit of wireless data communication device of the present invention: claims 6 to 13)
FIG. 1 shows a configuration example of a slave unit of the wireless data communication device of the present invention. It is assumed that at least one link channel for establishing a wireless link is provided between a master unit and a slave unit (not shown).
[0021]
In the figure, the slave unit has a transmission / reception circuit 10 and a radio signal processing unit 20, and the radio signal processing unit 20 includes a link channel selection unit 21, a radio link establishment unit 22, and a power down control unit 23.
[0022]
The transmission / reception circuit 10 receives a radio wave transmitted from the master unit with an antenna, converts the radio wave into a reception radio signal, and outputs the radio signal to the radio signal processing unit 20. Further, the transmission radio signal input from the radio signal processing unit 20 is converted into a radio wave and transmitted from the antenna. Further, when the power down signal is input from the wireless signal processing unit 20, the transmitting / receiving circuit 10 stops the transmitting / receiving operation of the radio wave to reduce the power consumption.
[0023]
The wireless signal processing unit 20 performs a wireless data signal process on a received wireless data signal from the parent device among the received wireless signals input from the transmission / reception circuit 10 and outputs the result as a received data signal. The transmission data signal to the master unit is subjected to radio data signal processing and output to the transmission / reception circuit 10 as a transmission radio signal. In addition, a transmission radio control signal (for example, a connection request signal) for controlling radio communication is output to the transmission / reception circuit 10 as a transmission radio signal, and the radio communication among the reception radio signals input from the transmission / reception circuit 10 is controlled. Wireless control signal processing (e.g., a connection request response signal) for the reception.
[0024]
The link channel selecting means 21 is configured to select one of the available link channels, from which the wireless communication is not being performed, from among the prepared link channels when the slave unit is not connected.
[0025]
The wireless link establishment means 22 broadcasts a connection request signal including information on the child device and requesting connection to the parent device via the selected free link channel, and transmits the connection request signal from the parent device. It is configured to wait for a connection request response signal including the received connection permission information and to establish a wireless link when the connection request response signal is received within a predetermined time Taw from the transmission of the connection request signal.
[0026]
The power-down control unit 23 powers down the transmission / reception circuit 10 when the link channel selection unit 21 does not detect an empty link channel or when the wireless link establishment unit 22 does not receive a connection request response signal within a predetermined time Taw. In this configuration, a signal is transmitted to set a power-down state in which the power consumption level of the slave unit is reduced for a predetermined time Tpd, and thereafter, the apparatus returns from the power-down state and returns to the processing of the link channel selection unit 21.
[0027]
The power-down control means 23 randomly determines the power-down state time Tpd within a range of a predetermined minimum time Tpdmin and a predetermined maximum time Tpdmax (Tpdmax> Tpdmin) every time the power-down state is entered. And
[0028]
Hereinafter, in the first embodiment shown in FIGS. 2 to 4, the second embodiment shown in FIGS. 5 to 7, and the third embodiment shown in FIGS. The method will be described.
[0029]
(First Embodiment: Claims 1, 2, 6, 7, 8, 12)
FIG. 2 is a flowchart illustrating a wireless data communication start procedure of the slave unit according to the first embodiment. FIG. 3 shows a state transition of the first embodiment. FIG. 4 shows a wireless link establishment sequence between the slave unit and the master unit according to the first embodiment.
In FIG. 2, it is assumed that when the connection state value is 1, the connection state is established, when the connection state value is 0, the connection state is not established, and when the power down signal value is 1, a power down signal is output to the transmission / reception circuit 10.
[0030]
In FIGS. 2 and 3, when the slave unit starts operation or detects disconnection with the master unit, the slave unit randomly selects a link channel to be connected to the master unit from among the prepared link channels. One link channel candidate i is selected (S1, S2, link channel candidate selection state ST0). Next, for the selected link channel candidate i, the carrier sense time Tcs. A timer for measuring i is started to start carrier sense (S3, carrier sense state ST1). This carrier sense time Tcs. If another wireless communication is not detected during i, a link channel candidate i is selected as an empty link channel, and a connection request signal for requesting connection to the parent device is transmitted using this link channel i (S4). , S5, S6, connection request transmission state ST2), and a timer for measuring the response waiting time Taw of the connection request response signal is started (S7, connection request response waiting state ST3). If the connection request response signal from the master unit is received before the response waiting time Taw elapses, the connection permission information included in the connection request response signal is checked. (Status value = 1), and a wireless link is established with the master unit (S8, S9, S10, S11).
[0031]
Here, when another wireless signal is received during carrier sense (S5, ST1), when the response waiting time Taw times out without receiving a connection request response signal (S9, ST3), If the connection is not permitted (S10), the state transits to the power down state (S12, power down state ST4). In the power-down state, a timer for measuring the power-down time Tpd generated at random is started, and the transmission / reception circuit of the slave unit is stopped until the power-down time Tpd ends, thereby reducing power consumption. After the power down time Tpd is over, the procedure returns to the procedure of randomly selecting one link channel from the prepared link channels (S12, S13, S14, S2, link channel candidate selection state ST0).
[0032]
In the wireless link establishment sequence shown in FIG. 4, first, a link channel i is randomly selected. Here, the time required for selection is Tch sel. Since the link channel i is vacant due to carrier sense, a connection request signal is transmitted, but no connection request response signal is received from the master unit until the response waiting time Taw elapses. Thus, the power down state is set for the power down time Tpd1 generated at random, and then the link channel j is selected at random. However, since the link channel j is performing communication by carrier sense, the link channel j immediately enters the power-down state for a randomly generated power-down time Tpd2, and then selects the link channel k. Since the link channel k is empty due to carrier sense, a connection request signal is transmitted. In response to the connection request signal, a connection request response signal is received from the parent device until the response waiting time Taw elapses, so that a wireless link is established with the parent device.
[0033]
By setting the power-down time Tpd1 and Tpd2 randomly each time the power-down state is changed, even if a plurality of slaves accidentally simultaneously transmit a connection request signal and fail to connect to the master, The power down time in each slave unit can be different. As a result, the probability of successful transmission of the next carrier sense and connection request signal increases, and the time until communication starts can be reduced. The same applies to the following embodiments.
[0034]
(Second embodiment: Claims 1, 3, 4, 7, 9, 10)
FIG. 5 is a flowchart illustrating a wireless data communication start procedure of the slave unit according to the second embodiment. FIG. 6 shows a state transition of the second embodiment. FIG. 7 shows a wireless link establishment sequence between the slave unit and the master unit according to the second embodiment.
[0035]
In FIG. 5, it is assumed that when the connection state value is 1, the connection state is established, when the connection state value is 0, the connection state is not established, and when the power down signal value is 1, a power down signal is output to the transmission / reception circuit 10. It is assumed that the number of link channels prepared for establishing a wireless link between the slave unit and the preceding unit is n (an integer of 2 or more), and the link channel candidates i are sequentially selected from 1 as link channel candidates i.
[0036]
In FIGS. 5 and 6, when the slave unit starts operation or detects a disconnection with the master unit, one of the link channels prepared as a link channel to be connected to the master unit is selected. A link channel candidate i (= 1) is selected, and for the selected link channel candidate i, the carrier sense time Tcs. A timer for measuring i is started to start carrier sense (S1, S21, S3, link channel candidate selection state ST0, carrier sense state ST1). This carrier sense time Tcs. If another wireless communication is not detected during i, a link channel candidate i is selected as an empty link channel, and a connection request signal for requesting connection to the parent device is transmitted using this link channel i (S4). , S5, S6, connection request transmission state ST2), and a timer for measuring the response waiting time Taw of the connection request response signal is started (S7, connection request response waiting state ST3). If the connection request response signal from the master unit is received before the response waiting time Taw elapses, the connection permission information included in the connection request response signal is checked. (Status value = 1), and a wireless link is established with the master unit (S8, S9, S10, S11).
[0037]
Here, when another wireless signal is received during carrier sense (S5, ST1), carrier sense is repeated for the next link channel candidate i (= i + 1) in order until an empty link channel is found (S22, ST1). S23, S21, ST5, ST1). Then, when a free link channel is found, a connection request signal requesting connection to the master unit is transmitted using the link channel (S4, S5, S6, connection request transmission state ST2). The same applies hereinafter.
[0038]
On the other hand, when all of the prepared link channels are in communication (S23), when the response waiting time Taw times out without receiving a connection request response signal (S9, ST3), or when the connection to the master unit is established. Is not permitted (S10), the state transits to the power down state (S12, power down state ST4). In the power-down state, a timer for measuring the power-down time Tpd generated at random is started, and the transmission / reception circuit of the slave unit is stopped until the power-down time Tpd ends, thereby reducing power consumption. After the end of the power down time Tpd, the procedure returns to the procedure for selecting the link channel 1 from the prepared link channels (S12, S13, S14, S1, link channel candidate selection state ST0).
[0039]
In the wireless link establishment sequence shown in FIG. 7, first, link channel 1 is selected. Since the link channel 1 is vacant due to carrier sense, a connection request signal is transmitted, but no connection request response signal is received from the master unit until the response waiting time Taw elapses. Therefore, the power-down state is set for the power-down time Tpd1 generated at random, and then the first link channel 1 is selected. However, the link channel 1 is in communication by carrier sense, and then carrier sense is performed in the order of link channels 2, 3,..., N. However, since all link channels are in communication, they are generated randomly. The power-down state is set for the power-down time Tpd2, and then the first link channel 1 is selected. The connection request signal is transmitted because the link channel k is vacant by the same carrier sense, and the connection request response signal from the master unit is received before the response waiting time Taw elapses. Establish a wireless link to
[0040]
In the present embodiment, the carrier sense is performed in order from link channel 1 to link channel n. However, when the slave unit has information on the use frequency of the prepared link channel, the following is performed. To Carrier sense is performed for the prepared link channels in order from the least used link channel, and when a free link channel is detected, the link channel is selected, and when all the link channels are communicating, the power down state is set. Transition. As a result, an empty link channel can be efficiently found.
[0041]
(Third Embodiment: Claims 1, 5, 7, 11)
FIG. 8 is a flowchart illustrating a wireless data communication start procedure of the slave unit according to the third embodiment. FIG. 9 shows a state transition according to the third embodiment. FIG. 10 shows a wireless link establishment sequence between the slave unit and the master unit according to the third embodiment.
[0042]
In FIG. 8, it is assumed that when the connection state value is 1, the connection state is established, when the connection state value is 0, the connection state is not established, and when the power down signal value is 1, a power down signal is output to the transmission / reception circuit 10. Further, the number of prepared link channels for establishing a wireless link between the slave unit and the preceding unit is set to n (an integer of 2 or more), and link channel candidates for carrier sensing are sequentially selected from one. I do.
[0043]
In FIGS. 8 and 9, when the slave unit starts operation or detects disconnection with the master unit, all of the prepared link channels for finding the link channel connected to the master unit are used. , Carrier sense is started in order (S1, S21, S3, S4, S5, S22, S23, carrier sense state ST0 of all link channels). Here, each carrier sense time Tcs. If no other wireless communication is detected during i, the link channel candidate i is stored as an empty link channel (S31). Then, after the carrier sensing of all link channels is completed, if there is a free link channel, one link channel is selected at random from among them (S23, S32, S33, random selection state of free link channel ST1).
[0044]
Using this link channel, a connection request signal for requesting connection to the master unit is transmitted (S33, connection request transmission state ST2), and a timer for measuring a response waiting time Taw of the connection request response signal is started (S7, connection). Request response waiting state ST3). If the connection request response signal from the master unit is received before the response waiting time Taw elapses, the connection permission information included in the connection request response signal is checked. The state value is set to 1), and a wireless link with the master unit is established (S8, S9, S10, S11).
[0045]
Here, when there is no free link channel due to all carrier sense (S32, ST0), when the response waiting time Taw times out without receiving the connection request response signal (S9, ST3), or when the connection to the base unit is not established. If not permitted (S10), the state transits to the power down state (S12, power down state ST4). In the power-down state, a timer for measuring the power-down time Tpd generated at random is started, and the transmission / reception circuit of the slave unit is stopped until the power-down time Tpd ends, thereby reducing power consumption. After the end of the power down time Tpd, the procedure returns to the carrier sense procedure for all prepared link channels (S12, S13, S14, S1, carrier sense state ST0 for all link channels).
[0046]
In the radio link establishment sequence shown in FIG. 10, since at least one of the first and second carrier channels is empty in the carrier sensing of all the link channels, one of the empty link channels is randomly selected from the channels and the connection request signal is transmitted. The connection request response signal from the master unit is not received before the response waiting time Taw elapses. Therefore, the power-down state is set for the power-down time Tpd1 generated at random, and thereafter, carrier sense of all link channels is repeated. Next, since all the link channels are communicating, the power-down state is set for the power-down time Tpd2 generated at random, and thereafter, carrier sense of all the link channels is repeated. Here, one of the free link channels is randomly selected, a connection request signal is transmitted, and a connection request response signal from the parent device is received before the response waiting time Taw elapses. Establish a wireless link between
[0047]
【The invention's effect】
As described above, according to the present invention, an unconnected slave that is not connected to the master increases the probability of finding an empty link channel by randomly accessing one or more link channels, and increases the probability of finding a free link channel. Can be greatly reduced.
[0048]
Further, it is not necessary to constantly receive signals until the wireless link is established, and by providing a power-down state at appropriate intervals, power supply to the transmitting / receiving circuit can be stopped. Thereby, the power consumption of the slave unit in the unconnected state can be significantly reduced.
[0049]
In particular, according to the second and eighth aspects of the present invention, since each slave unit randomly selects a link channel and performs carrier sense, even if a plurality of slave units coincidently perform carrier sense by chance, the probability that the link channels are different is different. And the time to connection can be greatly reduced.
[0050]
Further, according to the third to fifth and ninth to eleventh aspects of the present invention, the handset selects the link channels in order or in the order of low use frequency and carries out carrier sense, thereby reducing the probability of finding an empty link channel. The time required for connection can be greatly reduced.
[0051]
Further, according to the invention described in claim 6 and claim 12, the power down time Tpd is randomly set each time the power down state is changed, so that even if a plurality of slaves happen to be simultaneously carrier sensed by accident, , The probability of successful carrier sensing is increased, and the time until the start of communication can be shortened.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of a slave unit of a wireless data communication device of the present invention.
FIG. 2 is a flowchart showing a wireless data communication start procedure of the slave unit according to the first embodiment;
FIG. 3 is a diagram illustrating a state transition according to the first embodiment;
FIG. 4 is a view showing a wireless link establishment sequence between the slave unit and the master unit according to the first embodiment;
FIG. 5 is a flowchart showing a wireless data communication start procedure of the slave unit according to the second embodiment;
FIG. 6 is a diagram illustrating a state transition according to the second embodiment.
FIG. 7 is a diagram showing a wireless link establishment sequence between a slave unit and a master unit according to the second embodiment;
FIG. 8 is a flowchart showing a wireless data communication start procedure of the slave unit according to the third embodiment.
FIG. 9 is a diagram illustrating a state transition according to the third embodiment.
FIG. 10 is a diagram showing a wireless link establishment sequence between a slave unit and a master unit according to the third embodiment.
[Explanation of symbols]
10 Transmitter / receiver circuit
20 Radio signal processing unit
21 Link channel selection means
22 Wireless link establishment means
23 Power down control means

Claims (13)

In a wireless data communication system for performing wireless data communication between at least one slave unit and a master unit connected to a predetermined network, an unconnected slave unit not connected to the master unit is connected to the master unit wirelessly. In a wireless data communication start method of establishing a link and transitioning to a connection state, and starting wireless data communication,
At least one link channel for establishing a wireless link between the slave and the master is provided,
The unconnected slave unit is
Selecting one of the free link channels in which wireless communication is not performed from the prepared link channels,
Via the selected free link channel, broadcast transmission of a connection request signal requesting a connection to the parent device, including the information of the child device,
It waits for a connection request response signal including connection permission information transmitted from the master unit that has received the connection request signal, and when the connection request response signal is received within a predetermined time Taw from the transmission of the connection request signal, the wireless communication unit Establish a link,
If the empty link channel is not detected, or if the connection request response signal is not received within the predetermined time Taw, the power-down state in which the power consumption level of the slave unit is reduced for the predetermined time Tpd, and then the power-down state A method for starting wireless data communication, wherein the method returns from a state and returns to the selection of the idle link channel. The wireless data communication start method according to claim 1,
In the step of selecting one of the available link channels, one of the prepared link channels is randomly selected, the carrier sense of the selected link channel is performed, and the wireless communication is performed. A wireless data communication starting method, wherein the link channel is selected when there is no wireless communication, and the state transitions to the power down state when wireless communication is being performed. The wireless data communication start method according to claim 1,
The step of selecting one of the free link channels includes sequentially performing carrier sense on the prepared link channels, selecting the link channel when a free link channel is detected, and performing wireless communication on all link channels. A wireless data communication start method, wherein a transition is made to the power down state when the wireless communication is performed. The wireless data communication start method according to claim 1,
The slave unit has information on the frequency of use of the prepared link channel,
The step of selecting one of the available link channels includes performing carrier sense in the order of the used link channel in the order of the prepared link channel, and selecting the link channel when detecting the available link channel. And a transition to the power-down state when wireless communication is being performed on all link channels. The wireless data communication start method according to claim 1,
The step of selecting one of the free link channels includes sequentially performing carrier sense on the prepared link channels, storing the link channel when detecting a free link channel, and performing carrier sense on all link channels. Performing any one of the free link channels, and transiting to the power-down state when the wireless communication is being performed on all the link channels. How to get started. The wireless data communication start method according to claim 1,
The slave unit randomly determines the power down state time Tpd within a range of a predetermined minimum time Tpdmin and a predetermined maximum time Tpdmax (Tpdmax> Tpdmin) every time the slave unit shifts to the power down state. Wireless data communication start method. Before performing wireless data communication between at least one slave and a master connected to a predetermined network, an unconnected slave that is not connected to the master establishes a wireless link with the master. In the wireless data communication device to set the connection state and start wireless data communication,
At least one link channel for establishing a wireless link between the slave and the master is provided,
The slave unit is
Link channel selecting means for selecting, from the prepared link channels, one of free link channels in which wireless communication is not performed, in the unconnected state;
Via the selected free link channel, broadcast-transmits a connection request signal containing information on the child device and requesting a connection to the parent device, and transmits the connection transmitted from the parent device to the connection request signal. A wireless link establishing unit that waits for a connection request response signal including permission information and establishes the wireless link when the connection request response signal is received within a predetermined time Taw from the transmission of the connection request signal;
If the link channel selecting means does not detect an empty link channel, or if the wireless link establishing means does not receive a connection request response signal within a predetermined time Taw, the power consumption level of the slave unit is reduced by a predetermined time Tpd. And a power-down control unit for returning to a process of the link channel selecting unit after returning from the power-down state. The wireless data communication device according to claim 7,
The link channel selecting means randomly selects one link channel from the prepared link channels, performs carrier sense on the selected link channel, and, when wireless communication is not performed, the link channel. Is transmitted to the wireless link establishing means. The wireless data communication device according to claim 7,
The link channel selecting means is configured to sequentially perform carrier sense on the prepared link channels, and to transmit a link channel to the wireless link establishing means when detecting a free link channel. Wireless data communication device. The wireless data communication device according to claim 7,
The slave unit has information on the frequency of use of the prepared link channel,
The link channel selecting means performs carrier sense on the prepared link channels in order from the link channel with the lowest frequency of use, and sends out the link channel to the wireless link establishing means when detecting a free link channel. A wireless data communication device having a configuration. The wireless data communication device according to claim 7,
The link channel selecting means performs carrier sense for the prepared link channels in order, stores the link channel when detecting a free link channel, and performs carrier sense for all link channels after performing carrier sense for all link channels. A wireless data communication apparatus characterized in that any one link channel is selected from the channels and transmitted to the wireless link establishing means. The wireless data communication device according to claim 7,
The power down control means randomly determines the power down state time Tpd within a range of a predetermined minimum time Tpdmin and a predetermined maximum time Tpdmax (Tpdmax> Tpdmin) every time the power down state is shifted. A wireless data communication device, characterized in that: The wireless data communication device according to claim 7,
The slave unit includes a transmission / reception circuit for transmitting / receiving a radio wave to / from the master unit, and when a power-down signal is output from the power-down control unit, the transmission / reception circuit is stopped to reduce power consumption. A wireless data communication device, comprising:

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