JP2005057601A - Radio terminal and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio terminal and a radio communication method which allow the power consumption to be reduced in a standby state. <P>SOLUTION: In the case that a radio terminal transmits a network entry request signal in a network entry request signal transmission/reception time zone and does't receive a network entry request signal from another radio terminal in the network entry request signal transmission/reception time zone, the radio terminal reduces the power till the end of the relivant time slot. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wireless communication method in which a portable information terminal that operates on a battery power source and performs wireless data communication such as wireless LAN communication that can be carried and moved forms an ad hoc network and performs wireless data communication. The present invention relates to a reduction in power consumption until a communication partner is detected and communication is started when an ad hoc network is formed.

Conventionally, when an ad hoc network is configured between a plurality of terminals having a wireless function, there is a technique for all terminals belonging to the same group to recognize each other's address and communicate without using a wired LAN or a base station. To do.
For example, Patent Document 1 describes a wireless communication system in which a plurality of groups arbitrarily configured by a plurality of wireless terminals perform ad hoc peer-to-peer distributed network communication between wireless terminals belonging to each group. ing.

Specifically, the host terminal in the ad hoc network first broadcasts a packet including all member names (A) and the network address (B) unique to the host terminal as data, and waits.
The member terminal analyzes the received packet, extracts the information of (B) from the packet containing its own name, identifies it, and hosts the packet having each member name and the network address (C) unique to each member terminal as data. Send to the terminal.
The host terminal analyzes the received packet. If there is a member name belonging to the same group, the host terminal obtains (D) information contained in the packet, associates the member name with the terminal address, and saves the corresponding data. Keep it.
When a packet from all the member terminals cannot be received after a certain time, a packet with the data (A) and (B) input earlier is broadcast and waited.

Therefore, according to the wireless communication system, in an ad hoc network composed of wireless terminals, all terminals belonging to the same group can recognize and communicate with each other without a wired LAN and a base station.
Japanese Patent Laid-Open No. 10-23028

The conventional example shows a method for recognizing each other's address and communicating when the ad hoc network is formed. According to the present invention, the host terminal can identify all terminal names and host-specific names that are permitted to communicate. The terminal that has transmitted the network address and has received the data transmits a signal including the name of each terminal and the network address as information to the host to detect a communicable wireless terminal.
By the way, according to the present invention, when the wireless terminal cannot receive a signal from the host terminal, the wireless terminal operates the receiving circuit until the signal is received. At this time, the power supply unit in the wireless terminal needs to continuously supply power to the receiving circuit.
That is, in the standby state, there is a problem that the wireless terminal consumes power in the receiving circuit and consumes battery power even though it is not communicating.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a wireless terminal and a wireless communication method capable of reducing power consumption in a standby state.

  The present invention has been made to solve the above-described problems. The present invention constructs a network between a plurality of wireless terminals in a network entry request signal transmission / reception time zone and transmits / receives data in a wireless terminal communication time zone. When the wireless terminal transmits a network entry request signal during the network entry request signal transmission / reception time zone and does not receive a network entry request signal from another wireless terminal during the network entry request signal transmission / reception time zone, It is characterized by powering down until the end.

  In the present invention, when a network entry request signal is received from another wireless terminal during the network entry request signal transmission / reception time period, the wireless terminal constructs a network between the wireless terminals and ends the time slot. It is characterized by performing data communication until.

  In the present invention, the time slot includes a network entry request signal transmission / reception time zone and a communication time zone between wireless terminals, and a network entry request signal is transmitted from another wireless terminal during the network entry request signal transmission / reception time zone. When not receiving, it is characterized by powering down in the communication time zone between wireless terminals.

  Further, the present invention, when a network entry request signal including time information is received from another wireless terminal during the network entry request signal transmission / reception time zone, transmits a connection request signal to the other wireless terminal, When a connection response signal is received from the wireless terminal, data communication is performed until the time slot ends based on the time information.

  In addition, the present invention is characterized in that when a connection response signal is received from the other wireless terminal, power is down when data communication is not performed.

  Further, the present invention detects the network entry request signal in the next time slot when it detects that communication of another wireless terminal and transmission of a network entry request signal of another wireless terminal are not performed for one time slot period. A network entry request signal is transmitted in the transmission / reception time zone, and the network entry operation of the next time slot is repeated.

  Further, the present invention is characterized in that the time of the time slot is corrected based on GPS or radio clock information.

  Further, the present invention is characterized in that, in the network entry request signal transmission / reception time zone, a connection request transmission waiting time for transmitting a network entry request signal is set at random within a predetermined time range.

  In the present invention, when a network entry request signal is received from another wireless terminal during the network entry request signal transmission / reception time period, a connection request transmission waiting time Taw for transmitting a connection request signal to the other wireless terminal is It is characterized by being set at random within a predetermined time range.

  The present invention is also a wireless communication method in a wireless data communication system that constructs a network between a plurality of wireless terminals in a network entry request signal transmission / reception time zone and transmits / receives data in a wireless terminal communication time zone, When a wireless terminal transmits a network entry request signal during the network entry request signal transmission / reception time zone and does not receive a network entry request signal from another wireless terminal during the network entry request signal transmission / reception time zone, the time slot ends. It is characterized by being powered down.

  In the present invention, when a network entry request signal is received from another wireless terminal during the network entry request signal transmission / reception time period, the wireless terminal constructs a network between the wireless terminals and ends the time slot. It is characterized by performing data communication until.

  In the present invention, the time slot includes a network entry request signal transmission / reception time zone and a communication time zone between wireless terminals, and a network entry request signal is transmitted from another wireless terminal during the network entry request signal transmission / reception time zone. When not receiving, the wireless terminal is powered down in a communication time zone between wireless terminals.

  In the present invention, when a network entry request signal is received from another wireless terminal during the network entry request signal transmission / reception time period, the wireless terminal transmits a connection request signal to the other wireless terminal, When a connection response signal is received from another wireless terminal, data communication is performed until the time slot ends.

  In the present invention, when a connection response signal is received from the other wireless terminal, the wireless terminal is powered down when data communication is not performed.

  In the present invention, when it is detected that communication of another wireless terminal and transmission of a network entry request signal of another wireless terminal are not performed for one time slot period, the wireless terminal The network entry request signal is transmitted during the network entry request signal transmission / reception time period, and the network entry operation of the next time slot is repeated.

  Further, the present invention is characterized in that the wireless terminal corrects the time of the time slot based on GPS or radio clock information.

  Further, the present invention is characterized in that, in the network entry request signal transmission / reception time zone, a connection request transmission waiting time for transmitting a network entry request signal is set at random within a predetermined time range.

  In the present invention, when a network entry request signal is received from another wireless terminal during the network entry request signal transmission / reception time period, a connection request transmission waiting time Taw for transmitting a connection request signal to the other wireless terminal is It is characterized by being set at random within a predetermined time range.

As described above, according to the present invention, a wireless terminal transmits a network entry request signal during a network entry request signal transmission / reception time period, and transmits a network entry request signal from another wireless terminal during a network entry request signal transmission / reception time period. If not received, power down until the time slot is over.
Therefore, a wireless terminal that does not construct a network can detect a network entry signal of another wireless terminal without operating a receiving circuit at all times, and can effectively reduce power consumption until connection. can get.

According to the present invention, when it is detected that communication of another wireless terminal and network entry request signal transmission of another wireless terminal are not performed during one time slot period, the network entry in the next time slot is detected. A network entry request signal is transmitted in the request signal transmission / reception time zone, and the network entry operation of the next time slot is repeated.
Therefore, even if the timer time in the wireless terminal is different from the timer of the wireless terminal of the communication partner, an effect that network entry is possible can be obtained.

According to the present invention, the time of the time slot is corrected based on GPS or radio clock information.
Therefore, the time synchronization of the wireless terminals is accurately performed, and the effect that the network entry is reliably performed can be obtained.

  Hereinafter, the best mode for carrying out the present invention will be described.

Hereinafter, an embodiment of a wireless terminal of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a wireless terminal 1 according to the present embodiment.
As shown in FIG. 1, the wireless terminal 1 includes a wireless unit 100, a wireless signal processing unit 110, a central processing unit 120, a display unit 130, an operation unit 140, a storage unit 150, a clock unit 200, And a clock correction unit 210.
The radio unit 100 performs data input / output with the plurality of other radio terminals 2 and the radio signal processing unit 110. That is, the radio unit 100 receives radio waves radiated from the radio terminal 2 and outputs the radio waves to the radio signal processing unit 110, and converts a transmission signal input from the radio signal processing unit 110 into radio radio waves. 2 is transmitted. Further, the radio unit 100 stops transmission / reception of radio waves based on the power-down signal input from the radio signal processing unit 110, and reduces the power consumption level.

The wireless signal processing unit 110 performs processing for wireless signal processing. That is, the data signal input / output by the central processing unit 120 is converted into a wireless data signal input / output by the wireless unit 100.
Further, the wireless signal processing unit 110 generates and interprets a wireless control signal (connection request signal or the like), and performs wireless signal control (radio communication state transition determination or the like).
Radio signal processing section 110 outputs a power-down signal instructing power down to radio section 100 based on the state of radio communication and clock information input from clock section 200.

The central processing unit 120 implements various functions as a mobile terminal in the display unit 130, the operation unit 140, and the storage unit 150. Further, the central processing unit 120 notifies the wireless signal processing unit 110 of the presence / absence of data to be communicated. Further, the central processing unit 120 performs data input / output with the wireless signal processing unit 110 in the data communication state.
The clock unit 200 generates a plurality of timer values for controlling the radio signal processing unit 110, outputs the timer values to the radio signal processing unit 110 as clock information, and inputs the time correction signal output from the clock correction unit 210, Correct the time.
The clock correction unit 210 outputs a time correction signal including a synchronization time to the clock unit 200 based on GPS or radio clock information, and corrects the time of the clock unit 200.

Next, the operation of the wireless terminal of this embodiment will be described with reference to the drawings. FIG. 2 is a time chart showing transmission / reception signals between the wireless terminals 1 and 2 of the present embodiment.
In FIG. 2, the right direction indicates the time progression direction, and time t = 0 to 2T is shown as an example.
First, in FIG. 2, T, Tw, and Ten are respectively T: time slot period Tw: network entry request signal transmission waiting time zone
Ten: Network entry request signal transmission / reception time zone (where Ten> Tw)
Indicates. The wireless terminal communication time zone (T-Ten) indicates a time during which the wireless terminal 1 communicates with the wireless terminal 2 when a network entry request signal is received. In addition, the entry power down time (T-Ten) is the power down until the next network entry request transmission / reception time starts after the end of the network entry request signal transmission / reception time when the network entry request signal is not received. Indicates the time to do.

As shown in FIG. 2, network entry processing is executed at a preset time slot period T. In the time slot period T, the wireless terminals 1 and 2 hold the time slot period T in advance, and each wireless terminal may transmit and receive information on the time slot period T at the same time when the entry request signal is transmitted and received. Conceivable.
In each time slot delimited by the time slot period T, a network entry request signal transmission / reception time zone (Ten) and a communication time zone between wireless terminals (T-Ten), or a network entry request signal transmission / reception time zone (Ten) An entry power down time zone (T-Ten) is configured.

  In the network entry request signal transmission / reception time zone (Ten), the wireless terminals 1 and 2 enter the network. Specifically, the wireless terminals 1 and 2 have passed the network entry request signal transmission waiting time zone Tw from the start time (t = 0) of the network entry request signal transmission / reception time zone in the network entry request signal transmitting / receiving time zone (Ten). At this time (t = Tw), a network entry request signal is broadcasted.

For example, when the radio signal intensity is lower than a predetermined value due to radio signal attenuation and the network entry request signal transmission / reception time zone (Ten) has passed without receiving the network entry request signal from another wireless terminal ( At t = Ten), the wireless terminals 1 and 2 transition to the entry power down time zone (T-Ten).
Then, in the entry power down time zone (T-Ten), the wireless terminals 1 and 2 are powered down until the time slot ends, that is, t = T.
Then, when the time lot period T has elapsed (t = T), the wireless terminals 1 and 2 finish the power down, transition to the next time slot, and repeatedly execute the network entry process (t = T˜). 2T).

  That is, in the network entry request signal transmission / reception time zone (Ten), the network entry request signal transmission / reception time zone Tw has elapsed from the start time (t = T) of the network entry request signal transmission / reception time zone (t = T + Tw). Broadcasts an entry request signal.

On the other hand, when a network entry request signal is received from another wireless terminal in the network entry request signal transmission / reception time zone (Ten), for example, when the wireless terminal 1 receives a network entry request signal from the wireless terminal 2, When the request signal transmission / reception time zone (Ten) has elapsed (t = T + Ten), the wireless terminals 1 and 2 transition to the wireless terminal communication time zone (T-Ten).
In the wireless terminal communication time zone (T-Ten), the wireless terminals 1 and 2 establish a network between the wireless terminals, and until the time slot ends, that is, until t = 2T. Data communication between them.
When the time lot period T has elapsed (t = 2T), the wireless terminals 1 and 2 end the data communication, transition to the next time slot, and repeatedly execute network entry processing (t = T˜ 2T).

This state will be described with reference to the state transition diagram of the wireless terminal 1 of the present embodiment shown in FIG. 3. In the unconnected state with other wireless terminals, the wireless terminals 1 and 2 set the timer value t to 0 ( Reset) to start the network entry reception time (state 0). Then, at the timer value t = Tw (state 1), the wireless terminals 1 and 2 broadcast the network entry request signal.
When a network entry request signal is received from another wireless terminal at Tw <timer value t <Ten, the wireless terminals 1 and 2 transition to state 2 and the entry request reception time has ended at timer value t = Ten. In response, communication time between wireless terminals is started (state 3).
That is, when Ten <timer value t <T, connection between wireless terminals and data communication are performed.

On the other hand, if the network entry request signal is not received from another wireless terminal when Tw <timer value t <Ten, the wireless terminals 1 and 2 indicate that the entry request reception time has ended when the timer value t = Ten. In response, the state transits to state 4 and is powered down when Ten <timer value t <T.
Then, the wireless terminals 1 and 2 finish the power down at the timer value t = T (state 5), and transition to the state 0 again. Then, the routines of states 0 to 5 are repeatedly executed until a network entry request signal is received from another wireless terminal.

As described above, according to the wireless terminal 1 of the present embodiment, in a wireless communication system in which a plurality of wireless terminals construct a network and transmit / receive data, a network entry request signal transmission / reception time within a predetermined time slot period T. When each wireless terminal transmits an entry request signal and receives an entry request signal from another terminal during this time period, it communicates with that terminal until the end of the time slot and receives an entry request from the other terminal. If no signal is received, power down until the end of the time slot.
That is, in the connection waiting state, the wireless terminal 1 stops the wireless unit 100.
Therefore, the wireless terminal 1 can obtain an effect of significantly reducing power consumption until it is connected to the network.
In addition, according to the wireless terminal 1 of the present embodiment, transmission / reception of network entry signals between wireless terminals is performed at a predetermined time without using time synchronization with other wireless terminals using a wireless terminal internal clock. Operation is possible.
Therefore, an effect that signal transmission / reception between the wireless terminals 1 and 2 in each time slot can be performed reliably is obtained.
Further, according to the wireless terminal 1 of the present embodiment, time correction is performed using a GPS, a radio clock, or the like. Therefore, time synchronization between the wireless terminals 1 and 2 is accurately performed.
Therefore, an effect that signal transmission / reception between the wireless terminals 1 and 2 in each time slot can be performed reliably is obtained.

Hereinafter, a second embodiment of the wireless terminal of the present invention will be described with reference to the drawings.
Since the basic configuration of the wireless terminal 1 according to the present embodiment is as shown in the configuration diagram of FIG. 1, the description thereof will be omitted, and the differences from the first embodiment will be described below.
First, in FIG.
Taw: Connection signal transmission waiting time Tc: Connection request signal reception time Tw: Tc, Tapd
Tapd: Indicates the time from when Ack is received until transmission starts.

As shown in FIG. 4, the operation from t = 0 to T + Ten is the same as that of the first embodiment.
When a network entry request signal is received from another wireless terminal in the network entry request signal transmission / reception time zone (Ten), for example, when the wireless terminal 1 receives a network entry request signal from the wireless terminal 2, When the request signal transmission / reception time zone (Ten) has elapsed (t = T + Ten), the wireless terminal 1 transitions to the wireless terminal communication time zone (T-Ten).
Then, the wireless terminal 1 transmits a connection request signal to the other wireless terminals 2 when the connection signal transmission waiting time Taw elapses (t = T + Ten + Taw) in the wireless terminal communication time zone (T-Ten). To do. The connection request signal is received by the wireless terminal 2, and the wireless terminal 2 returns a connection response signal (Ack).

When a connection response signal (Ack) is received from the wireless terminal 2 that has received the connection request signal, a network is constructed between the wireless terminals 1 and 2.
Then, at the time (t = T + Ten + Tc) when the connection request signal reception time (Tc) elapses from the end of the network entry request signal transmission / reception time zone (t = T + Ten), the wireless terminal 1 performs the data communication waiting time (Tapd) That is, the power is down for T + Ten + Tc <t <T + Ten + Tc + Tapd.
Then, when the data communication waiting time elapses (t = T + Ten + Tc + Tapd), the wireless terminal 1 ends the power down and performs data communication between the wireless terminals until the time slot ends, that is, until t = 2T. I do.
When the time lot period T has elapsed (t = 2T), the wireless terminals 1 and 2 end the data communication, transition to the next time slot, and repeatedly execute the network entry process.

This will be described with reference to a state transition diagram of the wireless terminal 1 of the present embodiment shown in FIG. First, the correspondence between the states in the state transition diagram shown in FIG. 3 and the state transition diagram shown in FIG. 5 will be described.
State 0 in FIG. 3: State 0 in FIG.
State 1 in FIG. 1: State 1 in FIG.
State 2 in FIG. 3: State 2 in FIG.
State 3 in FIG. 3: State 3 in FIG.
State 4 in FIG. 3: State 7 in FIG.
State 5 in FIG. 3: State 8 in FIG.
To correspond. That is, in the states 4, 5, and 6 in FIG. 5, the wireless terminal 1 of the present embodiment is different from the first embodiment.

Now, in a non-connected state with other wireless terminals, the wireless terminals 1 and 2 set (reset) the timer value t to 0 and start the network entry reception time (state 0). Then, at the timer value t = Tw (state 1), the wireless terminals 1 and 2 broadcast the network entry request signal.
When a network entry request signal is received from another wireless terminal at Tw <timer value t <Ten, the wireless terminals 1 and 2 transition to state 2 and the entry request reception time has ended at timer value t = Ten. In response, communication time between wireless terminals is started (state 3).
Specifically, when the wireless terminal 1 receives a network entry request signal from the wireless terminal 2, in Ten <timer value t <Ten + Taw, it waits for connection request signal transmission to the wireless terminal 2, and in timer value t = Ten + Taw, In response to the end of the connection request signal transmission waiting time, a connection request signal is transmitted (state 4).

Then, when Ten + Taw <timer value t <Ten + Tc, a connection response signal (Ack) from the wireless terminal 2 is waited. When the Ack is received in the state 4, the network connection is established between the wireless terminals 1 and 2 (connection state), and the wireless terminal receives the end of the connection request signal reception time at the timer value t = Ten + Tc. 1 starts power-down during the data communication waiting time (Tapd), that is, during T + Ten + Tc <t <T + Ten + Tc + Tapd (state 5).
Then, the wireless terminal 1 ends the power down at the timer value t = T + Ten + Tc + Tapd, and performs data communication with the wireless terminal 2 until the time slot ends (state 6). When data communication is not performed in the time slot, the wireless terminal 1 continues to power down until the time slot ends.

On the other hand, if the network entry request signal is not received from another wireless terminal when Tw <timer value t <Ten, the wireless terminals 1 and 2 indicate that the entry request reception time has ended when the timer value t = Ten. In response, the state transits to state 7 and powers down when Ten <timer value t <T.
Further, when the connection response signal (Ack) from the wireless terminal 2 is not received when Ten + Taw <timer value t <Ten + Tc, the wireless terminals 1 and 2 end the connection request signal reception time at the timer value t = Ten + Tc. In response to this, the state transits to state 7 and powers down when Ten + Tc <timer value t <T.
Then, the wireless terminals 1 and 2 end the power down at the timer value t = T (state 8), and transition to the state 0 again. Then, the routines of the states 0, 1, 7, and 8 or the routines of the states 0 to 4, 7, and 8 are repeatedly executed until a network entry request signal is received from another wireless terminal.

As described above, according to the wireless terminal 1 of the present embodiment, power is down after the establishment of the network until the start of data communication.
That is, the wireless terminal 1 stops the wireless unit 100 during the time from the connection request signal transmission to the start of communication.
Therefore, the wireless terminal 1 can obtain an effect of greatly reducing power consumption until the start of data communication after the network is established.

Hereinafter, a third embodiment of the wireless terminal of the present invention will be described with reference to the drawings.
Since the basic configuration of the wireless terminal 1 according to the present embodiment is as shown in the configuration diagram of FIG. 1, the description thereof will be omitted, and the differences from the first embodiment will be described below.
As shown in FIG. 6, the operations from t = 0 to T in the wireless devices 1 and 2 are the same as those in the case where the network entry request signal is not received from another wireless terminal in the first embodiment. That is, the wireless device 1 enters the network in the network entry request signal transmission / reception time zone (Ten). Specifically, the wireless terminals 1 and 2 have passed the network entry request signal transmission waiting time zone Tw from the start time (t = 0) of the network entry request signal transmission / reception time zone in the network entry request signal transmitting / receiving time zone (Ten). At this time (t = Tw), a network entry request signal is broadcasted.

For example, when the radio signal intensity is lower than a predetermined value due to radio signal attenuation and the network entry request signal transmission / reception time zone (Ten) has passed without receiving the network entry request signal from another wireless terminal ( At t = Ten), the wireless terminals 1 and 2 transition to the entry power down time zone (T-Ten).
Then, in the entry power-down time period (T-Ten), the wireless terminals 1 and 2 are powered down until the time slot ends, that is, t = T (note that FIG. 6 shows the power-down state). Etc. are partially simplified).
Then, when the time lot period T has elapsed (t = T), the wireless terminals 1 and 2 finish the power down, transition to the next time slot, and repeatedly execute the network entry process (t = T˜). 2T). For the sake of simplicity, hereinafter, the timer value t is reset at t = T, 2T,..., NT (where n is a natural number), and is shown in parentheses in FIG.

Here, in the wireless terminal 1 of the present embodiment, during the period from the start time of network entry (t = 0) to the end time of one time slot period (t = T), data communication of other wireless terminals, and When a network entry request signal is not transmitted from another wireless terminal, this is detected by CSMA / CA (carrier sense multiple access / collision avoidance method).
At the end of detection (t = T, where reset is described as t = 0 hereinafter), the wireless terminal 1 randomly sets the network entry request signal transmission waiting time (Tw) between 0 <Tw <Ten. Generate as a valid value.
Next, the wireless terminal 1 similarly broadcasts the network entry request signal when the generated network entry request signal transmission waiting time (Tw) has elapsed (t = Tw).

When a network entry request signal is received from another wireless terminal in the network entry request signal transmission / reception time zone (Ten), the network entry request signal transmission / reception time zone (Ten) has elapsed as in the first embodiment. At the time (t = Ten), the wireless terminal 1 transitions to the wireless terminal communication time zone (T-Ten).
In the wireless terminal communication time zone (T-Ten), the wireless terminal 1 generates a connection signal transmission waiting time (Taw) as a random value between 0 <Taw <Tc.
The wireless terminal 1 transmits a connection request signal to the other wireless terminal 2 at the time when the generated connection signal transmission waiting time Taw elapses (t = T + Ten + Taw). The connection request signal is received by the wireless terminal 2, and the wireless terminal 2 returns a connection response signal (Ack).

When a connection response signal (Ack) is received from the wireless terminal 2 that has received the connection request signal, a network is constructed between the wireless terminals 1 and 2.
Then, at the time (t = Ten + Tc) when the connection request signal reception time (Tc) elapses from the end of the network entry request signal transmission / reception time zone (t = Ten), the wireless terminal 1 performs the data communication waiting time (Tapd) That is, the power is reduced during Ten + Tc <t <Ten + Tc + Tapd.
Then, when the data communication waiting time elapses (t = + Ten + Tc + Tapd), the wireless terminal 1 terminates power-down and performs data communication between the wireless terminals until the time slot ends, that is, until t = 2T. I do.
On the other hand, when the network entry request signal transmission / reception time zone (Ten) has elapsed without receiving the network entry request signal from the radio terminal 2 (t = Ten), the radio terminal 1 again returns to the entry power down time zone ( Transition to (T-Ten).
In the entry power-down time period (T-Ten), the wireless terminal 1 is powered down until the time slot ends, that is, t = T.
Then, when the time lot period T has elapsed (t = T), the wireless terminal 1 ends the data communication, transitions to the next time slot, and repeatedly executes the network entry process.

This will be described with reference to a state transition diagram of the wireless terminal 1 of the present embodiment shown in FIG. First, the correspondence between the states in the state transition diagram shown in FIG. 3 and the state transition diagram shown in FIG. 7 will be described.
State 0 in FIG. 3: State 0 and 1 in FIG.
State 1 in FIG. 3: State 2 in FIG.
State 2 in FIG. 3: State 3 in FIG.
State 3 in FIG. 3: State 4 in FIG.
State 4 in FIG. 3: State 5 in FIG.
State 5 in FIG. 3: State 6 in FIG.
To correspond. That is, particularly in state 1 in FIG. 7, the wireless terminal 1 of the present embodiment is different from the first embodiment.

Now, in a non-connected state with other wireless terminals, the wireless terminals 1 and 2 set (reset) the timer value t to 0 and start the network entry reception time (state 0). Then, the wireless terminals 1 and 2 operate in the same manner as when the network entry request signal is not received from other wireless terminals in the first embodiment until the timer value t = 0 to T, specifically, When 0 <timer value t <T, data communication of another wireless terminal and transmission of a network entry request signal from another wireless terminal are not detected by CSMA / CA.
Then, at the timer value t = T, the wireless terminals 1 and 2 end CSMA / CA and set (reset) the timer value t to 0 again (state 1).

Next, the wireless terminals 1 and 2 generate the network entry request signal transmission waiting time (Tw) as a random value between 0 <Tw <Ten, and at the timer value t = Tw (state 2), the clock unit 200 Broadcasts a network entry request signal including time information generated by the.
When a network entry request signal including time information is received from another wireless terminal at Tw <timer value t <Ten, the wireless terminals 1 and 2 transition to state 3 and receive an entry request at timer value t = Ten. When the time is over, the communication time between wireless terminals is started.
Specifically, when the wireless terminal 1 receives a network entry request signal from the wireless terminal 2, the clock correction unit 210 corrects the time generated by the clock unit 200 based on the time information of the received network entry request signal. . The wireless terminal 1 generates a connection signal transmission waiting time (Taw) as a random value between 0 <Taw <Tc, and waits for connection request signal transmission to the wireless terminal 2 when Ten <timer value t <Ten + Taw. In response to the end of the connection request signal transmission waiting time at the timer value t = Ten + Taw, a connection request signal is transmitted (state 4).
When the connection response signal (Ack) is received from the wireless terminal 2 that has received the connection request signal, a network connection is established between the wireless terminals 1 and 2 (connection state), and the wireless terminals 1 and 2 receive the timer value t. Data communication is performed between wireless terminals until = T.

On the other hand, if the network entry request signal is not received from another wireless terminal when Tw <timer value t <Ten, the wireless terminals 1 and 2 indicate that the entry request reception time has ended when the timer value t = Ten. In response, the state transits to the state 5 and is powered down when Ten <timer value t <T.
Then, the wireless terminals 1 and 2 finish the power down at the timer value t = T (state 6), and transition to the state 2 again. The routines in states 2 and 5 are repeatedly executed until a network entry request signal is received from another wireless terminal.

As described above, according to the wireless terminal 1 of the present embodiment, in the first time slot at the start of network entry, the presence or absence of a carrier wave output by another wireless terminal is detected (carrier sense), and the clock unit 200 Since the network entry request signal including the time information to be generated is broadcast, even if the timer value is deviated between the wireless terminals constituting the network, this is corrected and the time slot is adjusted.
Therefore, it is possible to obtain an effect that data can be transmitted and received in a time slot that is reliably determined.

Further, according to the wireless terminal 1 of the present embodiment, the network entry request signal transmission waiting time band Tw is randomly generated in each wireless terminal, and therefore the network entry request signal transmission waiting time band Tw is different in each wireless terminal. Value.
Therefore, when a plurality of wireless terminals exist in a range where wireless communication is possible, the time of the wireless terminal clock is different from that of the wireless terminal of the communication partner, and the network entry reception time Tw continues to be at the same timing. Even in such a case, it is possible to prevent the network entry request signals from being mutually received and being unable to be connected.
Further, according to the wireless terminal 1 of the present embodiment, since the connection signal transmission waiting time Taw is randomly generated in each wireless terminal, the connection signal transmission waiting time Taw has a different value in each wireless terminal.
Therefore, when a plurality of wireless terminals exist in a range where wireless communication is possible, the time of the wireless terminal clock is different from the clock of the wireless terminal of the communication partner, and the connection signal transmission waiting time Taw continues at the same timing. Even in such a case, it is possible to prevent the connection request signals from being mutually received and preventing the connection from being lost.

The above-described wireless terminals 1 and 2 have a computer system inside.
A series of processes relating to the above-described network establishment process, power management process, and time correction process are stored in a computer-readable recording medium in the form of a program, and this program is read and executed by the computer. The above processing is performed.
That is, each processing means and processing unit in the wireless terminals 1 and 2 is such that a central processing unit such as a CPU reads the above program into a main storage device such as a ROM or RAM and executes information processing / calculation processing. Is realized.
Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

1 is a configuration diagram of a wireless terminal 1. FIG. 3 is a time chart showing transmission / reception signals between the wireless terminals 1 and 2 according to the first embodiment. FIG. 3 is a state transition diagram of the wireless terminals 1 and 2 in the first embodiment. 9 is a time chart showing transmission / reception signals between the wireless terminals 1 and 2 according to the second embodiment. FIG. 6 is a state transition diagram of wireless terminals 1 and 2 in the second embodiment. 9 is a time chart showing transmission / reception signals between wireless terminals 1 and 2 according to the third embodiment. FIG. 6 is a state transition diagram of wireless terminals 1 and 2 in the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Wireless terminal 100 ... Wireless part 110 ... Wireless signal processing part 120 ... Central processing part 130 ... Display part 140 ... Operation part 150 ... Storage part 200 ... Clock part 210 ... Clock correction part

Claims (18)

A wireless terminal that constructs a network between a plurality of wireless terminals in a network entry request signal transmission / reception time zone and transmits / receives data in a communication time zone between wireless terminals,
Sending a network entry request signal in the network entry request signal transmission / reception time zone;
A wireless terminal characterized in that when it does not receive a network entry request signal from another wireless terminal during the network entry request signal transmission / reception time zone, it powers down until the time slot ends. When a network entry request signal is received from another wireless terminal during the network entry request signal transmission / reception time zone, the wireless terminal establishes a network between the wireless terminals and performs data communication until the end of the time slot. The wireless terminal according to claim 1, wherein: The time slot is composed of a network entry request signal transmission / reception time zone and a wireless terminal communication time zone,
3. The wireless terminal according to claim 1, wherein when the network entry request signal is not received from another wireless terminal during the network entry request signal transmission / reception time zone, the wireless terminal is powered down in a communication time zone between wireless terminals. 4. . When a network entry request signal including time information is received from another wireless terminal in the network entry request signal transmission / reception time zone, a connection request signal is transmitted to the other wireless terminal, and a connection response is received from the other wireless terminal. The wireless terminal according to claim 3, wherein when a signal is received, data communication is performed based on the time information until the time slot ends. 5. The wireless terminal according to claim 4, wherein, when a connection response signal is received from the other wireless terminal, power is down when data communication is not performed. When it is detected that the communication of another wireless terminal and the transmission of the network entry request signal of the other wireless terminal are not performed for one time slot period, the network entry is transmitted in the network entry request signal transmission / reception time zone in the next time slot. The wireless terminal according to any one of claims 1 to 5, wherein the wireless terminal transmits a request signal and repeats the network entry operation of the next time slot. The wireless terminal according to any one of claims 1 to 6, wherein the time of the time slot is corrected based on GPS or radio clock information. The wireless terminal according to claim 1, wherein a connection request transmission waiting time for transmitting a network entry request signal in the network entry request signal transmission / reception time zone is set at random within a predetermined time range. When a network entry request signal is received from another wireless terminal during the network entry request signal transmission / reception time zone, the connection request transmission waiting time Taw for transmitting a connection request signal to the other wireless terminal is within a predetermined time range. The wireless terminal according to claim 4, wherein the wireless terminal is set at random. A wireless communication method in a wireless data communication system for constructing a network between a plurality of wireless terminals in a network entry request signal transmission / reception time zone and transmitting / receiving data in a communication time zone between wireless terminals,
The wireless terminal is
Sending a network entry request signal in the network entry request signal transmission / reception time zone;
When the network entry request signal is not received from another wireless terminal during the network entry request signal transmission / reception time zone, the wireless communication method is characterized in that power down is performed until the time slot ends. When receiving a network entry request signal from another wireless terminal during the network entry request signal transmission / reception time zone, the wireless terminal establishes a network between the wireless terminals and performs data communication until the end of the time slot. The wireless communication method according to claim 10. The time slot is composed of a network entry request signal transmission / reception time zone and a wireless terminal communication time zone,
The wireless terminal is powered down in a communication time zone between wireless terminals when a network entry request signal is not received from another wireless terminal during the network entry request signal transmission / reception time zone. The wireless communication method described in 1. When a network entry request signal is received from another wireless terminal during the network entry request signal transmission / reception time period, the wireless terminal transmits a connection request signal to the other wireless terminal and connects from the other wireless terminal. 13. The wireless communication method according to claim 12, wherein, when a response signal is received, data communication is performed until the time slot ends. The wireless communication method according to claim 13, wherein when a connection response signal is received from the other wireless terminal, the wireless terminal is powered down when data communication is not performed. When it is detected that communication of another wireless terminal and transmission of a network entry request signal of another wireless terminal are not performed during one time slot period, the wireless terminal transmits and receives the network entry request signal in the next time slot. The wireless communication method according to any one of claims 10 to 14, wherein a network entry request signal is transmitted in a time zone and the network entry operation of the next time slot is repeated. The wireless communication method according to any one of claims 10 to 15, wherein the wireless terminal corrects the time of a time slot based on GPS or radio clock information. The wireless communication method according to claim 10, wherein a connection request transmission waiting time for transmitting a network entry request signal in the network entry request signal transmission / reception time zone is set at random within a predetermined time range. . When a network entry request signal is received from another wireless terminal during the network entry request signal transmission / reception time zone, the connection request transmission waiting time Taw for transmitting a connection request signal to the other wireless terminal is within a predetermined time range. The wireless communication method according to claim 13, wherein the wireless communication method is set at random.

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