JP2003051087A - Equipment and system for radio communication and method for controlling radio communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a timer from deviating from correct time information to be synchronized by receiving erroneous time information in the case a data error occurs in a radio channel, for example, caused by transmission collision, etc., in radio communication equipment for setting and correcting the timer with time information received by radio communication. SOLUTION: In this radio communication equipment having a receiving part 1, the timer 4, a comparator 5 and a timer controlling part 6, the timer controlling part 6 uses time information received continuously by the first number of particular times to set an initial value of the timer 4 in the case of comparator 5 continuously decides that the time information received by the receiving part 1 is within an error range of the timer by the first number of particular times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a wireless LAN (Local Area Network) that performs synchronization by using time information.
The wireless communication device, the wireless communication system, and the method of controlling the wireless communication device, which are included in k), in particular, an accurate initial value can be set to the internal timer of the wireless communication device, and the efficiency of The present invention relates to a wireless communication device capable of performing good synchronization, a wireless communication system, and a method of controlling the wireless communication device.

[0002]

2. Description of the Related Art Conventionally, a wireless LAN (Local Area N
IEEE (the Institute of Electrical) that defines the MAC (Media Access Control) layer of
andElectronics Engineers, Inc: In the 802.11 standard, each wireless communication terminal (hereinafter referred to as STA (Station)) has an internal TSF (Timing Synchronization Function) timer that holds time information, and an infrastructure. In the structure mode, each terminal belongs to a group (hereinafter referred to as BSS (Basic Serv
access point (hereinafter referred to as A)
It is specified that the TSF timer of P (Access Point) is synchronized. Therefore, AP is
, The STA periodically transmits a beacon frame reflecting the value of its own TSF timer, and each STA uses its time information included in the beacon frame transmitted from the AP forming the BSS to which it belongs to determine its own TSF timer. Update. The beacon frame is a frame generated by the MAC layer in a fixed cycle in the IEEE 802.11 standard, and the AP notifies each STA of control information by this beacon frame. This enables the power saving mode of each STA, band management by the AP, and the like.

In updating the TSF timer, a collision of communication or the like occurs in a wireless communication path, so that the AP
May cause an error in the time information sent by
By receiving the beacon frame containing the incorrect time information, each STA may make an incorrect correction to its TSF timer. In this way, if an erroneous correction is made at the time of updating the TSF timer, some STAs forming the wireless LAN have a TSF timer that is not synchronized with the AP's TSF timer. T
Confusion occurs in the mechanism of the wireless LAN that operates by referring to the value of the SF timer.

Further, as an extension of the IEEE 802.11 standard, there is a proposal to incorporate a mechanism for allocating a used band for each STA to each STA according to TSF timer information. In such a mechanism, if there is a STA that constitutes a wireless LAN and has a TSF timer that is not synchronized with the TSF timer of the AP of the BSS to which it belongs, the STA uses the originally allocated transfer band. Can not. In addition, STAs with out-of-sync TSF timers are more likely to violate the bandwidth allocated to other STAs, thus degrading the quality of data transfer at the BSS.

Here, as a device for preventing the clock inside the device from deviating from the accurate time, Japanese Patent Laid-Open No. 10-328 is known.
Japanese Unexamined Patent Publication No. 60 discloses a radio selective calling receiver which corrects a clock therein by the received time information. Here, the method adopted by the radio selective call receiver disclosed in the above publication is applied to the correction of the TSF timer of the STA, that is, the TSF timer of the STA is the TSF of the AP of the BSS to which the STA belongs. Consider using the method disclosed in the above publication in order to reduce the probability of deviation from the timer.

The radio selective call receiver disclosed in the above publication only when the time information received from the outside is within an error range corresponding to the accuracy of the internal clock compared with the time measured by the internal clock. The received time information is used to correct the time of the internal clock included therein. Here, the process of correcting the time of the internal clock disclosed in the publication will be described below with reference to the flowchart shown in FIG.

As shown in the figure, in the method disclosed in the above publication, the initial value of the internal clock is set in step 101 after activation of the radio selective calling receiver (S10).
1) Then, the process proceeds to step 102. Step 102
Then, it is confirmed whether or not the time information is received from the outside (S102), and when the time information is received from the outside, the process proceeds to step 103. It is to be noted that until the time information is received from the outside in step 102, the confirmation of whether the time information in step 102 is received is continued. In step 103, it is determined whether the received time information is within the error range corresponding to the accuracy of the internal clock (S103). If it is determined in step 103 that the time information received from the outside is within the error range corresponding to the accuracy of the internal clock, the process proceeds to step 104,
If it is determined that the error is outside the error range corresponding to the accuracy of the internal clock, the internal clock is not corrected and the process proceeds to step 102.
In step 104, the internal clock is corrected using the received time information (S104). Subsequently, the process proceeds to step 102, and the confirmation as to whether or not the time information has been received from the outside is repeated.

As described above, in the method of correcting the internal clock of the radio selective calling receiver described in the above publication, it is determined whether the time information received in step 103 is within the error range corresponding to the accuracy of the internal clock. In order to correctly determine whether or not, an accurate initial value needs to be set in step 101 after activation.

Therefore, the method disclosed in the above publication is
When applied to the correction of the TSF timer of each STA based on the time information included in the beacon frame in the EEE 802.11 standard, the probability that the TSF timer of itself shifts after the initial setting is completed due to the correction using the incorrect time information In order to reduce, the TSF timer needs to be provided with an accurate initial value immediately after the activation of each STA.

[0010]

[Problems to be Solved by the Invention] However, the TSF
The time transition of the timer, that is, time information, is
It is unique to S and is not uniquely determined (absolute time) in a wide area such as the time described in the above publication. Therefore, each STA must set an initial value that matches the value of the TSF timer to be synchronized when the TSF timer is activated, by using the time information included in the beacon frame received from the AP of the BSS to which it belongs. If there is a probability that an error will occur in the received time information, an appropriate initial value cannot be determined.

Here, as explained above, STA and A
In wireless communication with P, an error may occur in the time information transmitted by the AP due to communication collision or the like on the wireless communication path. Therefore, if the initial value of the TSF timer of the STA is set from the time information included in the beacon frame received from the AP of the BSS to which the STA belongs, an incorrect initial value may be set.

As described above, when the incorrect time information is set as the initial value, for example, even when the correct time information is received, it is determined that the correct time information is outside the error range corresponding to the accuracy of the TSF timer. Occurs. For example, if the difference from the correct initial value is set to be larger than the error corresponding to the accuracy of the TSF timer as the initial value of the TSF timer, the TSF timer cannot be corrected by receiving the correct time information. .

That is, if an incorrect initial value is set in the TSF timer, it is impossible to correctly determine whether or not the time information received thereafter is correct time information. Therefore, the TSF timer is set to correct time information. However, there is a problem that the correction may not be possible. As described above, when an error occurs in the time information and there is a possibility of receiving the incorrect time information, by using the incorrect time information for setting the initial value of the TSF timer of the STA, In addition, there is a problem that it may not be possible to appropriately correct the TSF timer.

Even when the initial value of the TSF timer is correctly set, for example, erroneous time information is continuously received within an error range for correcting the TSF timer, and the erroneous time information causes the TSF timer to be received. It is possible for the timer to be continuously corrected. In this case, the value of the TSF timer of the STA is set to a value outside the error range corresponding to the accuracy of the TSF timer of the STA with respect to the value of the TSF timer of the AP to be synchronized. That is, TSF of AP to be synchronized
The value of the timer is out of the correction range of the TSF timer of the STA. In this way, once the value of the STA's TSF timer is set to a value outside the correction range with respect to the value of the TSF timer of the AP to be synchronized, the value of the STA's TSF timer is changed to the AP to be synchronized. There is also a problem that the time information of the TSF timer cannot be autonomously restored.

An object of the present invention is to solve these problems, and to set and correct an internal timer by using time information received by wireless communication. To provide a wireless communication device, a wireless communication system, and a method for controlling a wireless communication device that can reduce the probability that an internal timer deviates from time information to be synchronized even if there is a possibility of receiving information. .

[0016]

In order to solve the above-mentioned problems, a wireless communication apparatus of the present invention includes an internal timer that operates with a specific accuracy, and a receiving means that receives information from the outside.
A wireless communication device comprising: a determination unit that determines whether the time information included in the information is within an error range of the internal timer; and a control unit that controls the internal timer using the time information. Then, the control means, when the time information received by the receiving means is determined by the determining means to be within the error range of the internal timer for the first specific number of times, the first specific number of times. It is characterized in that the initial value of the internal timer is set using the time information which is continuously determined to be within the error range of the internal timer.

According to the above invention, in the control means, after the wireless communication device is activated, the determination means determines that the time information is within the error range of the internal timer continuously for the first specific number of times. In this case, the initial value of the internal timer is set by using any one of the time information determined to be within the error range of the internal timer for the first specific number of times.
For this reason, the receiving unit continuously determines the probability of using incorrect time information as the initial value of the internal timer, that is, the probability of setting an incorrect value as the initial value of the internal timer, for the first specific number of times. It can be less than the probability of receiving.

Further, by arbitrarily setting the first specific number of times, the probability of setting an incorrect initial value in the internal timer can be made less than or equal to the desired probability. The first specific number can be arbitrarily set in consideration of the accuracy of the internal timer, and therefore, for example, the first specific number is set to be small in a wireless communication device having an accurate internal timer, A large number of wireless devices have internal timers with low accuracy. As a result, the probability of setting an incorrect initial value in the internal timer can be made less than or equal to the desired probability.

In the present invention, the "initial value" of the internal timer means a value used as a reference for measuring the value of the internal timer, which is the value given to the internal timer first after the communication device is activated. It is not limited to only. The value of the internal timer is also used as a reference for determining whether the received time information is within the error range of the internal timer.

When there is a probability that the wireless communication device receives erroneous time information, for example, when the control means sets a value outside the error range of the internal timer as an initial value, the time information received after that is the correct time information. It cannot be correctly determined whether or not there is. That is, when a value that is outside the error range of the internal timer is set as the initial value as compared with the correct time information, it is not possible to correctly determine whether or not the time information received thereafter is correct. Therefore, it becomes impossible to correct the internal timer of the wireless communication device with the correct time information, and the network mechanism such as the wireless LAN that operates by referring to the value of the internal timer causes confusion.

On the other hand, the control means of the wireless communication apparatus of the present invention has the first time information contained within the error range of the internal timer, that is, within the error range corresponding to its accuracy, after the wireless communication apparatus is activated. When it is determined by the determination means that the signal has been continuously received a specific number of times, the initial value of the internal timer is set using any of the time information items that have been continuously received the specific number of times. Therefore, it is possible to reduce the probability that a value outside the error range of the internal timer is set as the initial value of the internal timer as compared with the correct time information.

That is, when the determining means determines that the received time information is within the error range of the internal timer for the first specific number of times, the received time information is correct time information. However, the probability of being outside the error range of the internal timer is low. That is, the probability that the received time information is outside the error range of the internal timer is outside the error range of the internal timer, and the time information having the same difference as the correct time information is continuously received the first specific number of times. Is equal to the probability of doing. Here, the probability that the difference from the correct time information is outside the error range corresponding to the accuracy of the internal timer and that the same size is continuously received is very low.

Therefore, when the determining unit determines that the time information is within the error range of the internal timer, the time information is continuously received for the first specific number of times. The probability of being outside the error range of the internal timer based on the correct time information is very low.

That is, the time information which is determined by the determining means to be within the error range of the internal timer continuously for the first specific number of times is compared with the correct time information and is within the error range of the internal timer. There is a very high probability. Therefore, even if the wireless communication device may receive erroneous time information from the outside, the determination means continuously determines that the time information is within the error range of the internal timer by the first specific number of times. In this case, it is possible to match the initial value of the internal timer with the correct time information by setting the initial value of the internal timer using the time information received in any one of the first specific times of continuous reception. Becomes
By this means, it is possible to efficiently synchronize the wireless communication device using the value of the internal timer.

The time information used for setting the initial value of the internal timer may be one time information or a plurality of time information. Further, when the initial value of the internal timer is set using one time information, it is preferable to use the last received time information among the time information received continuously for the first specific number of times. . Since the elapsed time after receiving the time information is short, it is not necessary to perform the arithmetic processing for correcting in consideration of the elapsed time from the reception, or even if it is necessary, the arithmetic processing is performed. Can be simple.

Further, the time information received by the receiving means is obtained by performing a correction process on the received time information in consideration of the delay occurring in the wireless communication path and the delay occurring in the receiving process. May be used.

In the present invention, the error range of the internal timer means an error conforming to the accuracy of the internal timer, that is, an error caused by the performance of the internal timer, and is expressed by using an error generated per unit time, for example. . When expressed using an error generated per unit time, for example, when a value obtained by the internal timer measuring the unit time is compared with correct time information, the difference is 10% with a probability of 99% or more. If it is within the range, the error per unit time of the internal timer is 10 microseconds, and the error range per unit time of the internal timer is 10 microseconds.

In the wireless communication apparatus of the present invention, the control means is operable after the determination means determines that the time information is within the error range of the internal timer for a first specific number of times. The internal timer is corrected by using the time information determined by the determination means to be within the error range of the internal timer, and the time information determined by the determination means to be outside the error range of the internal timer is the internal information. It may not be used for the correction of the timer.

According to the above invention, when the correct time information is received, the internal timer is corrected, and when the incorrect time information is received, the internal timer is not corrected. It is possible to prevent deviation from correct time information.

For example, the error of the time information caused by the collision of the information on the external wireless communication channel is very large as compared with the error of the internal timer. Therefore, the erroneous time information contained in the collision data and the value of the internal timer are included. Is outside the error range of the internal timer. Therefore, there is a high probability that the time information determined by the determining means to be outside the error range of the internal timer based on the value of the internal timer is erroneous time information including an error due to some cause. When such time information is received, the time information is judged by the judging means to be outside the error range of the internal timer. Therefore, it is possible to prevent the internal timer from being corrected by the incorrect time information and the value of the internal timer from largely deviating from the correct time information.

That is, the initial value of the internal timer of the present invention is the first specified number of times when the judgment means judges that the time information is within the error range of the internal timer for the first specified number of times. Since it is set using any of the time information received continuously, the probability of matching with the correct time information is very high as described above. Therefore, as a result of comparison with the value obtained by measuring the time by the internal timer based on the initial value, the time information determined by the determining means to be within the error range of the internal timer is the probability of being correct time information. Is very high. Therefore, the time information determined by the determining means to be outside the error range of the internal timer has a very high probability of being incorrect time information.

Therefore, the internal timer is corrected using the time information determined by the determination means to be within the error range of the internal timer, and the time information determined to be outside the error range of the internal timer is By not correcting the internal timer, even if incorrect time information may be received, the internal timer is corrected only when the correct time information is received, and the time information should be synchronized with the value of the internal timer. Can be matched.

Therefore, by correcting the internal timer using incorrect time information, it is possible to prevent the value from deviating from the correct time information. Accordingly, it is possible to provide a wireless communication device capable of preventing the inconvenience caused by the mismatch of the values of the internal timers when synchronizing the wireless communication device and efficiently performing the synchronization using the time information.

In the wireless communication apparatus of the present invention, the time information is determined by the determining means after the time information is within the error range of the internal timer for the first specific number of times. When it is continuously determined that the time information is out of the error range of the second specified number of times, the control unit determines that the time information is within the error range of the internal timer by the third specified number of times. In the case where the determination is made continuously, the initial value of the internal timer may be set using the time information determined to be within the error range of the internal timer continuously for the third specific number of times. Good.

According to the above invention, when the internal timer is deviated by more than the error range of the internal timer with respect to the correct time information to be synchronized, the internal timer is reset to reset the internal value. The timer value can be matched with the correct time information.

After the determination means determines that the time information is within the error range of the internal timer for the first specific number of times in succession, the value of the internal timer of the wireless communication device is the correct time to be synchronized. A situation may occur in which a transition is made with a value that is more than the error range of the internal timer with respect to the transition of information. In this case, when the correct time information is received, the difference between the received time information and the value of the internal timer becomes larger than the error range of the internal timer. Is likely to be received. Therefore, when the determination unit determines that the time information is outside the error range of the internal timer for the second specific number of times, the error of the internal timer is determined from the time information that the value of the internal timer should match. There is a high probability that it is out of range, that is, the internal timer is no longer in sync. The second specific number of times can be set arbitrarily, and can be set according to the accuracy of the internal timer and the accuracy required to detect that the internal timer is no longer in the synchronized state.

As described above, when the internal timer is not in the synchronized state, the control means continuously determines that the time information is within the error range of the internal timer by the third specific number of times. In this case, the internal timer is initialized again by using the time information determined continuously for the third specific number of times. Similar to the case where the first specific number of times is continuously determined to be within the error range of the internal timer described above, the time information determined continuously for the third specific number of times has a probability of being correct time information. Since it is very high, the value of the internal timer can be matched with the time information to be synchronized by re-initializing the internal timer by using the time information continuously received the third specific number of times. That is,
It is possible to autonomously return the internal timer to the synchronized state. The third specific number and the first specific number may be the same or different.

In order to solve the above-mentioned problems, a wireless communication system of the present invention comprises a plurality of the above-mentioned wireless communication devices and a reference wireless communication device including a transmitting means for transmitting information including time information. In the wireless communication system, the plurality of wireless communication devices receive all the internal timers of the plurality of wireless communication devices that form the wireless communication system by receiving the information including the time information from the reference wireless communication device. Are synchronized within the error range of each internal timer.

According to the above invention, it is possible to form a wireless communication system in which the internal timers of all the wireless communication devices are synchronized within the error range of the internal timer.
As a result, it is possible to provide a wireless communication system capable of performing communication with high transmission quality in which band allocation to a wireless communication device is performed using the value of the internal timer.

The initial setting method of the wireless communication device of the present invention is as follows:
In order to solve the above problems, an internal timer that operates with a specific accuracy, a receiving unit that receives information from the outside, and the internal timer is controlled using time information included in the information received by the receiving unit. A control method for a wireless communication device, comprising: a determining step of determining whether or not the time information received by the receiving means is within an error range of the internal timer; When it is determined that the time information is within the error range of the internal timer for the first specific number of times in succession, the time determined to be within the error range of the internal timer for the first specific number of times in succession. And an initial value setting step of setting an initial value of the internal timer by using information.

According to the above invention, even when the wireless communication device may receive incorrect time information from the outside, an appropriate initial value can be autonomously set in the internal timer.

That is, in the control method of the wireless communication device of the present invention, when it is determined in the determination step that the time information is within the error range of the internal timer for the first specific number of times, the first identification is performed. The method includes an initial value setting step of setting the initial value of the internal timer by using the time information determined continuously for the number of times. Therefore, it is possible to reduce the probability that a value outside the error range of the internal timer is set as the initial value of the internal timer as compared with the correct time information. Also,
By setting the first specified number of times arbitrarily, the probability that the initial value of the internal timer is outside the error range of the internal timer when compared with the correct time information can be set to a desired probability or less.

Therefore, even when the wireless communication device may receive erroneous time information from the outside, it is possible to set the initial value of the internal timer by using the correct time information. It is possible to match the time information to be synchronized. Therefore, it is possible to provide a wireless device control method capable of matching the value of the internal timer with the correct time information and efficiently synchronizing the wireless communication device using the value of the internal timer.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION [Embodiment 1] An embodiment of the present invention will be described with reference to FIGS. 1 and 2.
It is as follows. In this embodiment, a frame is received by wireless communication, the internal timer is initialized using the information (time information) of the timer attached to the received frame, and the internal timer is identified after the initialization is completed. A wireless communication terminal (wireless communication apparatus) that corrects an internal timer according to the accuracy of 1., a wireless communication system including the wireless communication terminal, and an initial setting method (control method) of the internal timer of the wireless communication terminal will be described. .

The wireless communication terminal according to the present embodiment sets the initial value of the internal timer and corrects the timer value of the internal timer by using the time information received from the outside. The time information obtained by performing the correction process may be used for the received time information in consideration of the delay occurring in 1) and the delay occurring in the receiving process.

FIG. 1 shows a schematic configuration of a wireless communication terminal having an internal timer correction mechanism of this embodiment. As shown in the figure, the wireless communication terminal according to the present embodiment includes a receiving unit (receiving unit) 1, an analyzing unit 2, an upper layer 3, a timer (internal timer).
4, comparator (determination means) 5, timer control unit (control means)
6 and an initial setting counter 7. The function of each constituent element of the wireless communication terminal will be described below.

The receiving unit 1 receives data from the outside via a wireless communication channel, and analyzes the received data.
Tell. The analyzing unit 2 receives the data from the receiving unit 1 and sends it to the upper layer 3, extracts time information from the received data, and sends the time information to the timer 4 and the comparator 5. The timer 4 measures a timer value, which is the time that the timer 4 should hold, and notifies the upper layer 3 of the timer value. Further, when the timer 4 receives the correction notification signal of the timer 4 from the timer control unit 6, it updates the timer value with the time information received from the analysis unit 2.

When the comparator 5 receives the time information from the analysis unit 2, the comparator 5 compares the transmitted time information with the timer value transmitted from the timer 4, and the difference between the two indicates a specific error corresponding to the accuracy of the timer 4. It is determined whether it is within the range, and the determination result is transmitted to the timer control unit 6.

The timer control unit 6 determines that the initialization has not been completed by the notification from the initialization counter 7 at the timing when the determination result is received from the comparator 5, and the time information indicates that the timer 4 has the time information. In the case where the comparator 5 notifies the determination result that the time difference is within the specific error range as compared with the time information to be measured, it is necessary to correct the timer 4 with the time information received from the analysis unit 2. To notify. In addition, when it is determined from the notification from the initial setting counter 7 that the initial setting is not completed, the timer control unit 6 notifies the initial setting counter 7 of the following notification according to the determination result of the comparator 5. I do. That is, when the determination result that the time information is within the specific error range is given, the timer control unit 6 notifies that the counter value is incremented and determines that the received time information is outside the specific error range. In the case of a result, it notifies that the counter value will be reset.

The initial setting counter 7 includes a timer control unit 6
The counter value is incremented and reset in accordance with the increment notification and the reset notification. The counter value for the initial setting counter 7 is
If the specified number of times is matched, the timer control unit 6 and the upper layer 3 are notified that the initial setting is completed. In the upper layer 3, the data received by the receiving unit 1 is processed, and it is determined that the timer value of the timer 4 is valid by the notification of the completion of the initialization of the timer 4 notified from the initialization counter 7. To do. That is, the upper layer 3 determines that the timer value of the timer 4 is measured based on the correct initial value by the notification of the completion of the initial setting from the initial setting counter 7.

The initial setting counter 7 informs the upper layer 3 and the timer control unit 6 that the initial setting is completed when the initial setting counter value matches the first specific count value. This is a notification, and the counter value for initial setting is 0 immediately after the wireless communication terminal according to the present embodiment is powered on. In addition, when the wireless communication terminal is powered on, the timer 4 always counts the timer value, and immediately after the power is turned on, the timer value 0 starts counting.

The wireless communication terminal having the above-mentioned configuration allows the timer 4
The procedure of the process of initial setting and correction of, that is, the method of controlling the wireless communication terminal will be described with reference to the flowchart shown in FIG. As shown in the figure, when the wireless communication terminal is powered on, in step 1, the timer control unit 6
Determines whether or not the time information is received via the receiving unit 1, that is, whether or not the time information is received by the notification of the determination result from the comparator 5 (S).
1). Then, when the timer control unit 6 receives the notification of the determination result from the comparator 5 and confirms that the time information has been received, the determination process of step 2 is performed.

In step 2, the timer control section 6
Based on the notification of the completion of the initial setting sent from the initial setting counter 7, it is determined whether or not the initial setting of the timer 4 is completed (S2). Then, in step 2,
If it is determined that the initialization of the timer 4 is completed, the process proceeds to step 3, and if it is determined that the initialization of the timer 4 is not completed, the process proceeds to step 5.

Here, the process of controlling the timer 4 by the timer control unit 6 is the process when it is determined in step 2 that the initialization is not completed, that is, (1) the process of performing the initialization and the process of step 2 The process when it is determined that the initialization of the timer 4 is completed, that is, (2) the correction process after completion of the initialization can be separately described. Therefore, the operation of the wireless communication device will be described below by dividing it into the above two processes.

(1) Initial setting process In the initial setting process, if the timer control unit 6 determines in step 2 that the initial setting is not completed, the process proceeds to step 5, and in step 5, the timer is set. The control unit 6 receives the determination result from the comparator 5,
It is determined whether the received time information is within the specific error range (S5).

As described above, immediately after the wireless communication terminal is started up, the timer 4 counts the initial value of the timer value at power-on as 0, and therefore the time received first after the wireless communication terminal is started up. It is very unlikely that the information is within the specific error range as compared with the timer value of the timer 4, that is, the difference between the time information and the timer value is within the specific error range of the timer 4.

Therefore, when the wireless communication device first receives the time information, the timer control unit 6 normally determines in step 5 that the received time information is not within the specific error range of the timer 4. It will be done and it will move to step 7. In step 7, the initial setting counter 7 is reset to the value set as the initial value of the counter (S7). Then, in step 4, the timer 4 is set according to the received time information, that is, the time information determined to be outside the specific error range of the timer 4 (S4), and the process proceeds to step 1. In the above description, the time information first received after the wireless communication terminal is activated has been described, but the above description also applies when it is determined in step 5 that time information outside the error range of the timer 4 is received. Processing is performed in the same manner as the processing performed.

Until the initialization of the timer 4 is completed, every time the time information is received (S1), it is determined whether the received time information is within the above-mentioned specific error range (S5). ). When it is determined in step 5 that the received time information is within the specific error range, the process proceeds to step 6, where the initial setting counter 7 is incremented (S6), and the received time information is the specific error. If it is determined that the value is out of the range, the process proceeds to step 7 to reset the initial setting counter 7 (S
7).

Here, when the time information that is the first specific number of times has changed from the time information that the counter value of the initial setting counter 7 is the first specific number of times minus 1 within the specific error range. Indicates that the counter value of the initial setting counter 7 matches the first specified number of times. That is, when the received time information changes within the specific error range for the first specific number of times in succession, the counter value of the initial setting counter 7 matches the first specific number of times.

In step 6, after the counter value of the initial setting counter 7 is incremented, that is, after the counter value is incremented by 1, the process proceeds to step 8, and the initial setting counter 7 has the counter value of the first specified number of times. (S8). Then, when the counter value does not match the first specific number of times,
Correct the timer without completing the initial setting (S
4) Go to step 1, and if they match, go to step 9 and notify the timer controller 6 of the completion of the initialization by the initialization counter 7 and complete the initialization of the timer 4 (S9). . In step 9, timer 4
After completing the initial settings of, correct the timer (S
4) After moving to step 1 and receiving time information thereafter, a correction process after completion of initial setting is performed by the time information.

As described above, the wireless communication terminal according to the present embodiment uses the time information received when the counter value of the initial setting counter 7 matches the first specified number of times to initialize the timer 4. The value is set. However, the time information used for setting the initial value is not limited to this, and may be any time information determined to be within the specific error range of the timer 4 for the first specific number of times in succession. Further, the number of time information used for setting the initial value of the timer 4 may be singular or plural. When the initial value of the timer 4 is set using a plurality of time information, the initial value may be estimated and obtained by comparing a plurality of time information, for example. Next, the correction process after completion of the initial setting will be described below.

(2) Correction processing after completion of initial setting As described above, after the initial setting is completed (S9), the received time information is compared with the time information received in step 3 and the timer value. Was done (S3)
As a result, when it is determined that the time information is within the specific error range, the process proceeds to step 4, and the timer value of the timer 4 is corrected based on the received time information (S4). On the other hand, when it is determined in step 3 that the time information is outside the specific error range, the timer 4 is not corrected and the process returns to step 1.

As described above, when it is determined that the wireless communication terminal according to the present embodiment has received the time information within the specific error range of the timer 4 for the first specific number of times in succession, the wireless communication terminal receives the time information. Set the initial value of timer 4 using the time information
The initial setting is completed. Therefore, it is possible to prevent the initial value of the timer 4 from being set using incorrect time information. For example, even if the time information first received after the wireless communication terminal is activated is incorrect time information such as time information included in the information colliding on the communication path of the wireless LAN, the first time information received It is possible to prevent a situation in which an incorrect initial value is set by using, and it becomes impossible to correct the timer value of the timer 4 using the correct time information received thereafter.

Furthermore, the wireless communication terminal of the present embodiment is
After the correct initial value is set to the timer value in the initial setting, the correct timer value is used to determine whether or not the received time information is correct. Therefore, the determination can be correctly performed. Further, after the initial setting is completed, the timer value is corrected only by the one determined to be the correct time information, so that the timer value can be matched with the correct time information by the correction. For this reason, it is possible to provide a wireless communication terminal that can perform efficient information communication by reliably performing synchronization using time information.

Further, the wireless communication terminal of the present embodiment can match the timer value with the correct time information based on the time information received from the outside. Therefore, by constructing a wireless communication system with a plurality of the above wireless communication terminals and a reference wireless communication apparatus including a transmission means for transmitting information including time information, the time information of the timers of the respective wireless communication terminals is matched. That is, it is possible to synchronize the wireless communication terminal forming the wireless communication system with the reference wireless communication device.

As a result, in a wireless communication system having a mechanism of allocating a used band for each time, the originally allocated transfer band cannot be used, and a wireless communication terminal that is not synchronized is allocated to another wireless communication terminal. It is possible to provide a wireless communication system in which it is possible to reliably prevent infringement of the bandwidth and to have good quality of information transfer.

[Second Embodiment] The following will describe another embodiment of the present invention in reference to FIGS. 3 and 4. In the present embodiment, when the wireless communication terminal described in the first embodiment further receives time information that is not within the specific error range as compared with the timer value for the second specific number of times, the wireless communication terminal described above again A wireless communication terminal having a mechanism for performing a timer value setting operation similar to the initial setting described above will be described.

FIG. 3 shows a schematic configuration of the wireless communication terminal of the present embodiment. As shown in the figure, in addition to the components of the wireless communication terminal of the first embodiment, the wireless communication terminal (wireless communication apparatus) of the present embodiment compares the timer value of timer 4 after completion of the initial setting. The resetting counter 8 holds the number of times the time information outside the specific error range of the timer 4 is continuously received.

Along with this, the timer control unit (control means) 16 provided in the wireless communication terminal of the present embodiment has an initial setting in addition to the function of the timer control unit 6 of the wireless communication terminal of the first embodiment. After the completion, the resetting counter 8 is notified that the received time information is compared with the timer value of the timer 4 and if the time value is not within the specific error range, the counter value is incremented. When it is within the specific error range, it has a function of notifying that the counter value is reset.

Here, when the counter value of the resetting counter 8 is equal to the second specific number of times, the resetting counter 8 notifies the resetting counter 7 of the reset signal, and the resetting operation is performed again. At the same time as resetting, the counter value of the resetting counter 8 itself is reset to the initial value. In the present embodiment, components having the same functions as those of the wireless communication terminal according to the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

By the wireless communication terminal having the above-mentioned configuration, the timer 4
The procedure of the process of initial setting and correction of, that is, the method of controlling the wireless communication terminal will be described with reference to the flowchart shown in FIG. The procedure of the process in the present embodiment is also the same as in the above-described first embodiment, the process of controlling the timer 4 by the timer control unit 16 is (1) the process of performing the initial setting, and (2) the process after the initial setting is completed. The correction process can be described separately.

In the present embodiment, (1) the process of performing the initial setting is the same as that of the first embodiment, so the description thereof will be omitted, but (2) the correction process after the completion of the initial setting will be described in the first embodiment.
Is different from. Specifically, (2) the operation of the execution timer control unit 16 in the correction process after the completion of the initialization is changed as follows from the operation of the timer control unit 6 in the first embodiment. The same processes as those described in the first embodiment will be assigned the same reference numerals and will not be described.

(2) Correction process after completion of initialization (1) Similar to the procedure described in the first embodiment, (2) Initialization after the process of performing initialization is completed and initialization of the timer 4 is completed. The correction process after the setting is completed will be described below.

As shown in FIG. 4, in step 3,
As a result of comparing the time information received by the wireless communication terminal with the timer value of the timer 4, when it is determined that it is within the specific error range of the timer 4, the process proceeds to step 10 and the counter value of the resetting counter 8 is reset ( S10). After resetting the counter value to the initial value, the process proceeds to step 4, the timer value of the timer 4 is corrected (set) using the received time information, and the process returns to step 1.

On the other hand, when it is determined in step 3 that the time information received by the wireless communication terminal is compared with the timer value, and it is determined that it is outside the specific error range of the timer 4, step 1
The process proceeds to 1 and the counter value of the resetting counter 8 is incremented (S11). When the counter value is incremented, the process proceeds to step 12 and the resetting counter 8
It is determined whether the counter value matches the second specific number of times (S12). If the counter value does not match, the timer value of the timer 4 is not corrected by the received time information and the step 1 is performed. Return to.

Here, when the received time information changes outside the specific error range for the second specific number of times in succession, the counter value of the resetting counter 8 matches the second specific number of times value. Becomes In step 12,
When the counter value of the resetting counter 8 matches the second specific number of times, the process proceeds to step 13, and the resetting counter 8 notifies the initializing counter 7 of resetting (S13). When the resetting counter 8 notifies the resetting, the process goes to step 14, and the initializing counter 7 cancels the notification of the completion of the initializing to the timer control unit 16 (S14). That is, the initialization counter 7 notifies the timer control unit 16 of cancellation of completion of initialization. After the notification is made by the initialization counter 7, when the wireless communication terminal receives the time information, it is determined in step 2 that the initialization has not been completed, and the procedure is the same as that described in the first embodiment. (1) Processing for performing initial setting is performed.

In the present embodiment, the initialization which is performed again after the initialization counter 7 notifies the cancellation of the completion of the initialization is performed by the same method as the initial initialization. The third specific number of times that the time information within the error range of the timer 4 is continuously received is not limited to the same number as the first specific number, and another number may be set. Thus, the initial value initially set after the wireless communication terminal is activated and the initial value reset again can be matched with the time information to be synchronized with their respective desired probabilities. For example, by setting the third specified number of times to be larger than the first specified number of times, the probability that the reset initial value matches the time information to be synchronized is first set after the activation of the wireless communication terminal. Can be higher than the initial value.

As described above, in the wireless communication terminal according to the present embodiment, (1) in the initial setting process, the received time information is counted by the timer 4 continuously for the first specified number of times.
When the transition is within the error range, the initial setting is completed, and when the time information is received after that, (2) the correction process after the completion of the initial setting is performed. Then, (2) in the correction process after completion of the initial setting, when the received time information has changed outside the specific error range of the timer 4 continuously for the second specific number of times, the time information is received thereafter. (1) The initial setting process is performed again. In other words, the timer value of the timer 4 is deviated from the time information to be synchronized by shifting each of the processing of (1) initialization and the processing of (2) correction processing after completion of initialization to the other processing under the above conditions. This is prevented, and when a shift occurs in the transition of the time information to be synchronized with the timer 4, the initialization is promptly performed again.

Therefore, even after the completion of the initialization immediately after the activation of the wireless communication terminal, if the timer 4 deviates from the transition of the time information to be synchronized, the initialization of the timer 4 is performed again, so that it is correct. The period in which the timer 4 is out of synchronization with the time information can be effectively reduced.

[Third Embodiment] The following description will explain still another embodiment of the present invention with reference to FIG.

In the present embodiment, as an embodiment of the wireless communication system of the present invention, the wireless communication system is set to the infrastructure mode of the wireless LAN system according to the IEEE 802.11 standard, and as an extension, each wireless terminal is provided hourly. A case where the present invention is applied to a system to which a mechanism for allocating a wireless band is added will be described.

In the wireless communication system of the present embodiment, in order to add a mechanism for allocating a wireless band to each wireless terminal every time in the infrastructure mode of the wireless LAN system according to the IEEE 802.11 standard, The functions such as are to be expanded.

An access point (hereinafter referred to as an AP (Access Point)) constituting the wireless communication system of the present embodiment is configured such that time information of its own timer and each wireless communication device (hereinafter referred to as STA (Station)) are wireless. Depending on the occupied period that occupies the media (wireless communication path), each STA
It is assumed that the wireless communication system has a mechanism for allocating the wireless band of 1) and notifying each STA of the information of the allocation by using an appropriate control frame. In addition, each STA has a mechanism for determining the transmission timing for transmitting the information using the information on the allocation of the wireless band notified by the AP and the time information of its own timer, and performing the communication during the determined period. And

As described above, by adding a mechanism for allocating a wireless band to each wireless terminal every time, time synchronization can be most effectively operated in the wireless communication system of the present embodiment. However, the wireless communication system according to the present embodiment can be applied to the wireless communication system according to the IEEE standard without extension for adding a mechanism for allocating a wireless band to each wireless terminal every time.
It is possible to apply to the infrastructure mode defined by 802.11.

I which is the wireless communication system of the present embodiment
FIG. 5 shows a schematic configuration of a wireless communication system in an infrastructure mode of a wireless LAN system according to the EEE 802.11 standard. As shown in the figure, the wireless communication system according to the present embodiment has an AP (reference wireless communication device) 101 and a BS that is a group formed by AP 101.
S102, and STAs (wireless communication devices) 103 to 105 belonging to BSS 102. The wireless communication system of the present embodiment includes STAs 103 to 105 as shown in FIG.
When the STAs 103 to 105 are not distinguished, they will be simply referred to as STAs. In addition, ST which constitutes the wireless communication system
The number of A is not particularly limited. And STA
Corresponds to a wireless communication device that receives information including time information from the AP 101 corresponding to the reference wireless communication device.

Both AP 101 and STA have timers (not shown) therein, and STA is AP
101 receives the time information of the timer of the AP 101 included in the beacon frame periodically transmitted by 101,
The own timer is set to AP 101 by using the received time information.
Synchronize with the timer. The timer of AP 101 and S
Since the synchronization of the TA with the timer can be performed in the same manner as in the above-described first and second embodiments, the description thereof will be omitted in this embodiment.

Here, the error range of the timer synchronization is I
The wireless system according to the present embodiment can be applied to the infrastructure mode of the wireless LAN system according to the IEEE 802.11 standard by setting the synchronization allowable error defined in IEEE 802.11 to 4 microseconds.

As a result, in the internal timer of the STA, it is possible to reduce the probability of the synchronization deviation with respect to the timer of the AP 101. That is, BSS102
Since it is possible to reduce the probability that the STAs configuring the STAs are out of synchronization with each other, the transmission time zone (transmission timing) assigned to the STAs by the AP 101 is reduced.
It is possible to suppress a decrease in the use efficiency of the wireless band due to the collision of Therefore, it is possible to provide the wireless communication system capable of performing the communication with high transmission quality in which the band is assigned to the wireless communication device by using the value of the internal timer.

The present invention can be configured as the following first wireless communication terminal or first wireless communication system.

The first radio communication terminal has an internal timer that operates with a specific accuracy, and a mechanism that sets and corrects the internal timer by using the time information included in the data received from the outside. In wireless communication terminals,
When the time information received from the outside is compared with the time information of the timer measured by the internal timer and is within the specified error range according to the specified accuracy, the time information included in the data received from the outside Correct the timer and compare the time information contained in the data received from the outside with the time information measured by the internal timer, and if it is outside the specified error range according to the specified accuracy, receive from the outside. It is determined that the internal timer is not corrected by the obtained time information and the initial value of the internal timer is set within the range of the above-mentioned specific accuracy, with the received time information continuing the fourth specific number of times. In this case, the value to be set is estimated and set from the time information received the fourth specific number of times.

The first wireless communication terminal, when the initial value of the internal timer has already been set, compares the time information measured by the internal timer with the time information that is outside the specific error range. May be received from the outside continuously for the fifth specific number of times, the initial value setting operation may be performed again.

The first wireless communication system is a wireless communication system composed of one or a plurality of the first wireless communication terminals and a wireless communication terminal for transmitting data including reference time information, The value of the internal timer may be synchronized within a specific error range in all the wireless communication terminals configuring the wireless communication system by receiving the data including the time information serving as the reference.

[0093]

As described above, in the wireless communication device,
If time information received by wireless communication is used, a function to set and correct an internal timer included therein is required, and if there is a possibility of receiving incorrect time information by wireless communication with a certain probability, this book The invention has the following effects. The internal timer can autonomously acquire an appropriate initial value based on the received time information. It is possible to reduce the probability that the internal timer is corrected due to incorrect time information. When the internal timer measures an incorrect time transition, it can autonomously return to the correct time transition.

In the wireless communication apparatus of the present invention, when the control unit determines that the time information received by the receiving unit is within the error range of the internal timer by the determining unit for the first specific number of times in succession. In addition, the initial value of the internal timer is set by using the time information which is determined to be within the error range of the internal timer continuously for the first specific number of times.

Therefore, it is possible to prevent a value that is more than the error range of the internal timer from the time information to be synchronized with the internal timer, as the initial value of the internal timer. This allows the initial value of the internal timer to match the correct time information even when the wireless communication device may receive incorrect time information from the outside. An effect that wireless communication of the device can be efficiently performed is achieved.

In the wireless communication device of the present invention,
The control means is within the error range of the internal timer by the determination means after the determination means has continuously determined the first specific number of times that the time information is within the error range of the internal timer. The internal timer may be corrected using the time information determined to be, and the time information determined to be outside the error range of the internal timer by the determination means may not be used for the correction of the internal timer. .

Therefore, if the correct time information is received, the internal timer is corrected, and if the incorrect time information is received, the internal timer is not corrected, and the value of the internal timer should be synchronized. It is possible to prevent deviation from correct time information. With this, it is possible to provide a wireless communication device capable of preventing the inconvenience caused by the mismatch of the values of the internal timers when synchronizing a plurality of wireless communication devices and efficiently performing the synchronization using the time information. Produce an effect.

In the wireless communication apparatus of the present invention, the time information is determined by the determining means after the time information is determined to be within the error range of the internal timer for the first specific number of times. If the time information is within the error range of the internal timer by the determining means, the control means receives the third specific number of times when the second specific number of times is continuously received if the time information is outside the error range. In the case where the determination is made continuously, the initial value of the internal timer may be set using the time information determined to be within the error range of the internal timer continuously for the third specific number of times. Good.

As a result, when the value of the internal timer deviates from the correct time information to be synchronized by exceeding the error range of the internal timer, the internal timer is initialized again and the value of the internal timer is corrected. It is possible to provide a wireless communication device that can be matched with time information.

As described above, the wireless communication system of the present invention is constituted by a plurality of the above-mentioned wireless communication devices and the reference wireless communication device including the transmitting means for transmitting the information including the time information. The plurality of wireless communication devices receive the information including the time information from the reference wireless communication device, so that all of the internal timers of the plurality of wireless communication devices configuring the wireless communication system are internal timers. It is synchronized within the error range of.

Therefore, it is possible to form a wireless communication system in which the internal timers are synchronized within the error range of the internal timers for all the wireless communication devices. As a result, it is possible to provide a wireless communication system capable of performing communication with high transmission quality in which band allocation to a wireless communication device is performed using the value of the internal timer.

As described above, the control method of the wireless communication apparatus of the present invention comprises the steps of determining whether the time information received by the receiving means is within the error range of the internal timer, and the above-mentioned determining step. When it is determined that the time information is within the error range of the internal timer for the first specific number of times in succession, it is determined that the time information is within the error range of the internal timer for the first specific number of times in succession. An initial value setting step of setting an initial value of the internal timer using time information.

Therefore, even when the wireless communication device may receive incorrect time information from the outside, it is possible to autonomously set a proper value as the initial value of the internal timer. Therefore, it is possible to provide a wireless device control method capable of matching the value of the internal timer with the correct time information and efficiently synchronizing the wireless communication device using the value of the internal timer. Play.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a wireless communication terminal according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a flow of a method of controlling an internal timer of the wireless communication device according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a schematic configuration of a wireless communication terminal according to a second embodiment of the present invention.

FIG. 4 is a flowchart showing a flow of a method of controlling an internal timer of the wireless communication device according to the second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a schematic configuration of a wireless communication system according to a third embodiment of the present invention.

FIG. 6 is a flowchart showing a flow of an example of a method for correcting the time of a clock included in a conventional wireless communication device.

[Explanation of symbols]

1 receiver (reception means) 2 analysis section 3 upper layers 4 timer (internal timer) 5 Comparator (determination means) 6, 16 Timer control unit (control means) 7 Initial setting counter 8 Reset counter 101 AP (reference wireless communication device) 102 BSS 103 STA (wireless communication device)

Continued front page    F term (reference) 2F073 AA16 AB01 BB01 BC02 CC09                       CC10 DD02 EE16 FG01 FG02                       GG01 GG08                 5K033 CB15 DA17 EC01                 5K047 AA18 GG02 GG11 HH21 KK04                       KK12 MM56                 5K067 AA26 BB21 DD30 EE02 FF05                       HH22

Claims (5)

[Claims] 1. An internal timer operating with a specific accuracy, a receiving means for receiving information from the outside, and a determining means for determining whether or not the time information included in the information is within an error range of the internal timer. And a control means for controlling the internal timer by using the time information, wherein the control means is characterized in that the time information received by the receiving means is an error of the internal timer by the determining means. If the first specific number of times is continuously determined to be within the range, the first
The wireless communication device is characterized in that the initial value of the internal timer is set using the time information determined to be within the error range of the internal timer continuously for the specific number of times. 2. The control means, after the determination means determines that the time information is within the error range of the internal timer for a first specified number of times in succession, the determination means determines the internal timer of the internal timer. The internal information is corrected using the time information determined to be within the error range, and the time information determined to be outside the error range of the internal timer by the determination means is not used for the correction of the internal timer. The wireless communication device according to claim 1, wherein 3. The time information is outside the error range of the internal timer after the determination means has continuously determined that the time information is within the error range of the internal timer for a first specific number of times. And the second specific number of consecutive determinations, the control unit determines the third specific number of consecutive determinations that the time information is within the error range of the internal timer by the determining unit. In this case, the initial value of the internal timer is set using the time information determined to be within the error range of the internal timer continuously for the third specific number of times. The wireless communication device according to. 4. A wireless communication system comprising a plurality of wireless communication devices according to claim 1, 2 or 3, and a reference wireless communication device including a transmission means for transmitting information including time information. Then, the plurality of wireless communication devices receives the information including the time information from the reference wireless communication device, so that all of the internal timers of the plurality of wireless communication devices configuring the wireless communication system have an error of each internal timer. A wireless communication system characterized by being synchronized within a range. 5. An internal timer that operates with a specific accuracy, a receiving unit that receives information from the outside, and a control unit that controls the internal timer using time information included in the information received by the receiving unit. A method of controlling a wireless communication device, comprising: a determining step of determining whether or not the time information received by the receiving means is within an error range of the internal timer; When the first specific number of times is continuously determined to be within the error range of the internal timer, the time information determined to be within the error range of the internal timer is continuously used by the first specific number of times. And a step of setting an initial value of the internal timer, the method of controlling a wireless communication device.