JP5321513B2 - Communication terminal, reception standby method, and program - Google Patents

Description

  The present invention relates to a communication terminal that performs connection with an access point by active scanning, a reception standby method, and a program.

  A terminal device such as a PC (Personal Computer) having a wireless LAN (Local Area Network) function is widespread. In recent years, since the compatibility with the Internet is high and it is easy to provide various services, there are an increasing number of products equipped with a wireless LAN function in small terminal devices such as mobile phones. In addition, home appliances such as DLNA (Digital Living Network Alliance) that can receive services by connecting to a LAN have been developed, and it is estimated that the demand for wireless LAN will increase in the future.

  Here, a battery capacity problem is a major issue when a wireless LAN function is installed in a small terminal device such as a mobile phone. A small terminal device such as a cellular phone has a small capacity of a battery that can be mounted, unlike home appliances and PCs, so that it is desired to reduce power consumption by a wireless LAN function. In addition, since the ratio of the power consumption by the wireless LAN to the power consumption of the entire terminal device is relatively large, the reduction of the power consumption of the wireless LAN leads to the reduction of the power consumption of the entire device. .

  By the way, when a device (communication terminal, access point) having a wireless LAN function performs signal transmission, it performs carrier sense or correlation signal sense, confirms surrounding wireless conditions, and determines that there is no noise in the surroundings. In addition, signal transmission is performed. Therefore, when a signal transmitted from one device is detected by carrier sense or correlation signal sense, the other device does not transmit a signal and waits for the next carrier sense.

Japanese Patent Laid-Open No. 2004-228561 performs carrier sense intermittently and, at the time of carrier sense, reduces the power consumption at the time of carrier sense by changing the intermittent time of carrier sense in conjunction with the current access status. Technology is disclosed.
Patent Document 2 discloses a technique for reducing packet collisions by extending the time interval from transmission of a data frame to transmission of the next data frame.
Patent Document 3 considers the number of access points that belong to the same mobility domain, the transmission rate of the network to which the access points are connected, the average degree of congestion, and the like as the time for which reception of responses from access points is closed. A technique for determining the position is disclosed.

JP 2008-172642 A JP 2008-211600 A JP 2009-088718 A

  In order to reduce the amount of power consumed by the wireless LAN function of the terminal device, the reception standby time, which is the time from when the request signal is transmitted by active scan until the response signal is terminated and the power saving state is entered Shortening the length. However, if the reception standby time is shortened, if the response signal from another access point interferes with the transmission of the response signal due to interference, the signal may be missed.

  The present invention has been made to solve the above-described problem, and is a communication terminal that connects to an access point by active scanning, and includes a transmission unit that transmits a request signal, and a response signal from the access point. A standby time storage unit for storing a reception standby time indicating a time until the reception standby is completed, and a minimum time for continuing the reception of the response signal from the time when the transmission unit transmits the request signal. Responding to a request signal transmitted from the access point from the access point to a time indicated by a longer one of the predetermined minimum reception waiting time indicated and the reception waiting time stored in the waiting time storage unit A receiving unit that waits for reception of a response signal to be received, and two consecutive response signals received by the receiving unit last A reception interval calculation unit that calculates a reception interval, and a standby time extension unit that rewrites the reception standby time stored in the standby time storage unit to a longer time as the reception interval calculated by the reception interval calculation unit is shorter. It is characterized by.

  In addition, the present invention provides a communication terminal provided with a standby time storage unit that stores a reception standby time indicating a time until connection with an access point is performed by active scanning and the reception of a response signal from the access point is ended. In this method, the transmitting unit transmits a request signal, and the receiving unit has a minimum time to continue waiting for reception of the response signal from the time when the transmitting unit transmits the request signal. In the request signal transmitted from the access point to the request signal transmitted from the access point until the time indicated by the longer minimum time among the predetermined minimum reception standby time indicating the standby time and the reception standby time stored in the standby time storage unit The reception interval calculation unit waits for reception of a response signal to respond, and the reception interval calculation unit receives two consecutive responses received by the reception unit last. Calculates a reception interval of items, extensions waiting time, as the reception interval of the reception interval calculating unit has calculated is shorter, characterized in that rewrites the reception waiting time the standby time storing unit stores a long time.

  In addition, the present invention provides a communication terminal provided with a standby time storage unit that stores a reception standby time indicating a time until connection with an access point is performed by active scanning and the reception of a response signal from the access point is ended. A transmission unit for transmitting a request signal, a predetermined minimum reception standby time indicating a minimum time for waiting for reception of the response signal from the time at which the transmission unit transmits the request signal, and the standby time storage unit The reception unit that waits for reception of a response signal in response to a request signal transmitted from the access point from the access point until the time indicated by the longer one of the reception standby times stored by the receiver, and the reception unit last A reception interval calculation unit for calculating a reception interval between two consecutive response signals received in the reception interval calculation unit As calculated reception interval that is short, a program for functioning as a waiting time extension rewrites the reception waiting time during which the standby time storing unit stores a long time.

  According to the present invention, the communication terminal increases the reception standby time as the reception interval of response signals from two consecutive access points received last is shorter. When there are many access points around the communication terminal, there is a high possibility that response signals transmitted by the access points are concentrated in a short time, so that the reception waiting time becomes long and the response signal can be prevented from being missed. On the other hand, when the number of communication terminals present in the surroundings is small, there is a high possibility that the reception interval of the response signal transmitted by the access point will be long, so the reception of the response signal will be waited with the minimum necessary reception waiting time. . Thereby, the power consumption of a communication terminal can be reduced.

It is a schematic block diagram which shows the structure of the communication terminal by the 1st Embodiment of this invention. It is a figure which shows operation | movement of the communication terminal by 1st Embodiment. It is a flowchart which shows operation | movement of a reception waiting time calculation process. It is a figure which shows operation | movement of the communication terminal by 2nd Embodiment. It is a flowchart which shows the operation | movement of a 2nd reception waiting time calculation process.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic block diagram showing the configuration of a communication terminal according to the first embodiment of the present invention.
The communication terminal 100 includes a flash memory 110, a wireless LAN unit 120, a CPU 130, a RAM 140 (standby time storage unit), a display unit 150, and a key input unit 160.

The flash memory 110 includes a control program storage unit 111 and a parameter storage unit 112.
The control program storage unit 111 stores a control program for controlling connection with the wireless LAN.
The parameter storage unit 112 stores parameters used for executing the control program. Specifically, the parameter storage unit 112 stores a maximum reception standby time, a minimum reception standby time, and an extension reference time. Here, the maximum reception standby time is the maximum time for which standby for reception of a response signal from the access point 200 is continued. Further, the minimum reception waiting time is a minimum time during which standby for receiving a response signal from the access point 200 is continued. The extension reference time is a parameter used when extending reception of a response signal from the access point 200 by executing a control program.
The parameters stored in the parameter storage unit 112 can be changed by operating the key input unit 160. Thereby, the user can set the parameter stored in the parameter storage unit 112 to a value suitable for the wireless environment.

The wireless LAN unit 120 includes a conversion unit 121, a transmission unit 122, and a reception unit 123.
The converter 121 converts the baseband request signal input from the CPU 130 into a radio signal and outputs the radio signal to the transmitter 122. In addition, the conversion unit 121 converts the wireless band response signal input from the reception unit 123 into a baseband signal and outputs the baseband signal to the CPU 130.
The transmission unit 122 transmits the request signal for the wireless band input from the conversion unit 121 to the access point 200.
The receiving unit 123 receives a wireless band response signal from the access point 200 and outputs the response signal to the converting unit 121. In addition, the reception unit 123 receives a reception standby end signal from the CPU 130, and ends the reception of the response signal.

The CPU 130 includes a reception interval calculation unit 131 and a standby time extension unit 132 by executing a control program stored in the control program storage unit 111.
The reception interval calculation unit 131 receives the response signal from the reception unit 123, calculates the reception interval between two consecutive response signals received last by the reception unit 123, and outputs the reception interval to the standby time extension unit 132.
The standby time extension unit 132 receives the response signal reception interval from the reception interval calculation unit 131, and extends the time until the reception of the response signal from the access point 200 is completed based on the reception interval.
The timer 133 measures the elapsed time from the time when the transmitter 122 transmits the request signal. In addition, the time measuring unit 133 outputs a reception standby end signal to the wireless LAN unit 120 when the time until the reception of the response signal from the access point 200 ends is completed.

The RAM 140 stores a program executed by the CPU 130 and parameters used in the program as a work area. Specifically, the RAM 140 stores an elapsed time after transmission, a reception standby time, a previous reception time, a standby extension time, a reception interval, and a standby time maximization flag. Here, the post-transmission elapsed time is an elapsed time after the transmission unit 122 transmits the request signal. The reception waiting time is the time until the reception of the response signal from the access point 200 ends. The previous reception time is the time from the time when the transmission unit 122 transmits the request signal to the time when the reception unit 123 receives the previous response signal. The standby extension time is an extension time of the reception standby time calculated by the standby time extension unit 132. The reception interval is a reception interval between two consecutive response signals received by the reception unit 123 last calculated by the reception interval calculation unit 131. The standby time maximization flag is a flag indicating whether or not the reception standby time has exceeded the maximum reception standby time stored in the parameter storage unit 112. That is, when the standby time maximization flag indicates “ON”, it indicates that the reception standby time has exceeded the maximum reception standby time. When the standby time maximization flag indicates “OFF”, the reception standby time is the maximum reception standby. Indicates that the time has not been exceeded.
The display unit 150 displays various information.
The key input unit 160 accepts data input.

In the communication terminal 100 having such a configuration, the transmission unit 122 transmits a request signal, and the reception unit 123 stores the minimum reception standby time stored in the parameter storage unit 112 from the time when the transmission unit 122 transmits the request signal. And the reception waiting time stored in the RAM 140, the reception of the response signal in response to the request signal transmitted from the transmission unit 122 from the access point 200 is waited for the time indicated by the longer time. Next, the reception interval calculation unit 131 calculates the reception interval of two consecutive response signals received last by the reception unit 123, and the standby time extension unit 132 has a short reception interval calculated by the reception interval calculation unit 131. The reception standby time stored in the RAM 140 is rewritten to a longer time.
As a result, the communication terminal 100 can wait for reception of the response signal from the access point 200 with the minimum necessary reception standby time.

Next, the operation of the communication terminal 100 according to the first embodiment will be described.
FIG. 2 is a diagram illustrating an operation of the communication terminal according to the first embodiment.
When the communication terminal 100 starts an active scan process by a user operation, the CPU 130 reads the control program from the control program storage unit 111 of the flash memory 110 to the RAM 140 and executes it.

  When executing the control program, the CPU 130 initializes the values of the parameters used for the control program stored in the RAM 140 to “0” (step S1). At this time, it is desirable to initialize all the parameters stored in the RAM 140, but it is not always necessary to initialize all the parameters. The CPU 130 at least the elapsed time after transmission, the previous reception time, and the waiting time maximization flag Should be initialized.

  Next, the CPU 130 outputs a request signal to the conversion unit 121 of the wireless LAN unit 120. The converter 121 converts the input request signal into a radio signal and outputs it to the transmitter 122. The transmission unit 122 transmits the input request signal for the wireless band to the access point 200 (step S2). At this time, the receiving unit 123 starts waiting for a response signal from the access point 200 (step S3). At this time, the time measuring unit 133 of the CPU 130 starts measuring the elapsed time from the time when the transmission unit 122 transmits the request signal, and records it in the elapsed time after transmission stored in the RAM 140 (step S4).

Next, the time measuring unit 133 determines whether or not the post-transmission elapsed time stored in the RAM 140 is equal to or less than the minimum reception standby time stored in the parameter storage unit 112 of the flash memory 110 (step S5).
When the time measuring unit 133 determines that the elapsed time after transmission is equal to or less than the minimum reception standby time (step S5: YES), the reception interval calculating unit 131 determines whether the receiving unit 123 has received a response signal from the access point 200. Is determined (step S6). When the receiving unit 123 has not received the response signal (step S6: NO), the process returns to step S5, and the elapsed time after transmission is compared with the minimum reception standby time.
On the other hand, when the reception unit 123 receives the response signal (step S6: YES), the conversion unit 121 converts the response signal in the radio band into a baseband signal and outputs it to the CPU 130. And CPU130 performs reception waiting time calculation processing (Step S7). The reception standby time extension process is a process for extending the reception standby time of the RAM 140 and rewriting it.

Here, the operation of the reception waiting time calculation process in step S7 will be described.
FIG. 3 is a flowchart showing the operation of the reception standby time calculation process.
When the CPU 130 starts the reception standby time calculation process, the reception interval calculation unit 131 determines whether or not the previous reception time stored in the RAM 140 indicates “0” (step S101). Since the parameters of the RAM 140 are initialized in step S1, it is understood that the response signal is received for the first time when the previous reception time indicates “0”.

  When the reception interval calculation unit 131 determines that the previous reception time indicates “0” (step S101: YES), the standby time extension unit 132 sets the parameter storage unit of the flash memory 110 to the standby extension time stored in the RAM 140. The value of the extended reference time stored in 112 is written (step S102). This is because when the access point 200 exists around the communication terminal 100, the reception unit 123 of the wireless LAN unit 120 receives the response signal in a time shorter than the minimum reception standby time stored in the parameter storage unit 112 of the flash memory 110. Therefore, the calculation with the smallest amount of calculation is selected.

  On the other hand, if the reception interval calculation unit 131 determines that the previous reception time does not indicate “0” (step S101: NO), the value obtained by subtracting the previous reception time from the post-transmission elapsed time stored in the RAM 140. Is written in the RAM 140 as a reception interval (step S103). Next, the standby time extension unit 132 divides the extension reference time stored in the parameter storage unit 112 of the flash memory 110 by the reception interval stored in the RAM 140, and writes the obtained value in the RAM 140 as the standby extension time (step S104). ). As a result, the shorter the reception interval, the longer the reception standby time. This is because when the receiving unit 123 receives response signals concentrated in a short period of time, there is a high possibility that many access points 200 exist in the vicinity, so that there is no missing response signal.

  When calculating the standby extension time in step S102 or S104, the standby time extension unit 132 adds the standby extension time to the elapsed time after transmission stored in the RAM 140, and writes the obtained value in the RAM 140 as the reception standby time (step S102). S105). Next, the standby time extension unit 132 rewrites the previous reception time stored in the RAM 140 with a value indicating the elapsed time after transmission (step S106), and ends the reception standby time calculation process.

  When the reception standby time calculation processing in step S7 is completed (FIG. 2), the time measuring unit 133 of the CPU 130 determines whether the reception standby time stored in the RAM 140 exceeds the minimum reception standby time stored in the parameter storage unit 112 of the flash memory 110. It is determined whether or not (step S8). When the time measuring unit 133 determines that the reception standby time is equal to or less than the minimum reception standby time (step S8: NO), the process returns to step S5, and the post-transmission elapsed time is compared with the minimum reception standby time.

On the other hand, when the timer 133 determines that the reception standby time exceeds the minimum reception standby time (step S8: YES), the maximum reception standby time stored in the parameter storage unit 112 of the flash memory 110 and the reception standby stored in the RAM 140 are stored. The time indicating the shorter time is read out (step S9). At this time, the timing unit 133 may determine whether the standby time maximization flag stored in the RAM 140 is ON / OFF. In this case, the timer 133 reads the maximum reception standby time when the standby time maximization flag indicates “ON”, and reads the reception standby time when it indicates “OFF”.
Next, the timer 133 determines whether or not the elapsed time after transmission stored in the RAM 140 is equal to or shorter than the time read in Step S9 (Step S10).

  When the time measuring unit 133 determines that the elapsed time after transmission is equal to or shorter than the time read in step S9 (step S10: YES), the reception interval calculation unit 131 has received the response signal from the access point 200 by the reception unit 123 It is determined whether or not (step S11). If the reception unit 123 has not received a response signal (step S11: NO), the process returns to step S9, and the reception standby time or the maximum reception standby time is compared with the elapsed time after transmission.

  On the other hand, when the reception unit 123 receives the response signal (step S11: YES), the conversion unit 121 converts the response signal in the radio band into a baseband signal and outputs it to the CPU 130. Next, the reception interval calculation unit 131 of the CPU 130 reads the standby time maximization flag from the RAM 140 and determines whether or not the standby time maximization flag indicates “ON” (step S12). That is, the reception interval calculation unit 131 determines whether the reception standby time exceeds the maximum reception standby time. When the reception interval calculation unit 131 determines that the standby time maximization flag indicates “ON” (step S12: NO), the process returns to step S9, and the reception standby time or the maximum reception standby time is compared with the post-transmission elapsed time. I do.

On the other hand, when the reception interval calculation unit 131 determines that the standby time maximization flag indicates “OFF” (step S12: YES), the CPU 130 executes the reception standby time calculation process described in step S7 (step S13). ).
When the reception standby time calculation process ends, the time measuring unit 133 of the CPU 130 determines whether or not the reception standby time stored in the RAM 140 is equal to or greater than the maximum reception standby time stored in the parameter storage unit 112 of the flash memory 110 ( Step S14). When the timer 133 determines that the reception standby time is less than the maximum reception standby time (step S14: NO), the process returns to step S9, and the reception standby time is compared with the elapsed time after transmission.

On the other hand, when it is determined that the reception standby time is equal to or longer than the maximum reception standby time (step S14: YES), the time measuring unit 133 rewrites the standby time maximization flag stored in the RAM 140 to “ON” (step S15), step Returning to S9, the maximum reception standby time is compared with the elapsed time after transmission.
Here, the reason why the standby time maximization flag is turned ON / OFF in step S12 will be described. If the reception standby time is equal to or greater than the maximum reception standby time, the maximum reception standby time is read out in step S9, and therefore, in step S10, a comparison process between the maximum reception standby time and the post-transmission elapsed time is performed. Therefore, in the processing after the reception standby time becomes equal to or greater than the maximum reception standby time, calculation using the reception standby time is not performed. Therefore, by rewriting the standby time maximization flag to “ON” in step S15 and omitting the reception standby time calculation process in steps S13 and S14 according to the determination in step S12, the calculation amount of the CPU 130 is reduced, and the communication terminal 100 The power saving can be achieved.

When the time measuring unit 133 determines in step S5 that the elapsed time after transmission exceeds the minimum reception standby time (step S5: NO), or in step S10, the elapsed time after transmission exceeds the time read in step S9. (Step S10: NO), the timer 133 outputs a reception standby end signal to the receiver 123. Next, the reception unit 123 inputs a reception standby end signal, and ends the reception standby process (step S16).
When the reception unit 123 ends the reception standby process, the communication terminal 100 ends the active scan process. Thereafter, the communication terminal 100 performs a connection process with the access point 200 using the response signal received by the receiving unit 123. Alternatively, the communication terminal 100 performs active scan processing under different conditions according to other settings.

As described above, according to the present embodiment, when the reception standby time is shorter than the minimum reception standby time, the reception unit 123 performs the access point 200 from the time when the transmission unit 122 transmits the request signal to the minimum reception standby time. Wait for reception of response signal from. Thereby, the communication terminal 100 can prevent the response signal from being missed from the access point 200 due to the reception standby time being too short.
When the reception standby time is longer than the minimum reception standby time and shorter than the maximum reception standby time, the reception unit 123 responds from the access point 200 between the time when the transmission unit 122 transmits the request signal and the reception standby time. Wait for receipt of. As a result, the communication terminal 100 can wait for reception of the response signal from the access point 200 with the minimum necessary reception standby time.
When the reception standby time is longer than the maximum reception standby time, the reception unit 123 waits for reception of a response signal from the access point 200 from the time when the transmission unit 122 transmits the request signal to the maximum reception standby time. . As a result, the communication terminal 100 can save power without prolonging standby for reception.

<Second Embodiment>
Next, a second embodiment of the present invention will be described.
In the second embodiment, in addition to the response time of the response signal, information is read from the response signal, and the standby time of the response signal is further appropriately controlled based on the information. Information read from the response signal includes, for example, the field strength, the number of retransmissions, and the number of transmission stops by CSMA / CA (Carrier Sense Multiple Access with Collision Avidance).

  Specifically, when the response signal has a very weak electric field strength, even when the response signal is received, even if the connection to the access point 200 is possible, there is a possibility that the connection signal is out of the connection range when actually connecting. Yes. Therefore, it is desirable not to treat a response signal with extremely weak electric field strength as effective information even if it is received.

  In addition, when the number of response signal retransmissions is excessive, there is a high possibility that a plurality of sudden noise sources due to short-range wireless communication such as Bluetooth (registered trademark) exist in the vicinity. For this reason, it is highly possible that the reception condition of the response signal is extremely bad. Therefore, it is desirable to increase the waiting time of the response signal.

  Further, when the number of transmission stops by CSMA / CA is excessive, there is a high possibility that there are many access points. Therefore, since it is assumed that response signals from many access points are received, it is desirable to lengthen the waiting time for response signals.

  In the second embodiment of the present invention, the response signal transmitted by the access point 200 stores the electric field strength, the number of retransmissions, and the number of transmission stops by CSMA / CA. The electric field strength (Signal Level) is a parameter included in the MAC layer of the response signal. However, since the number of retransmissions and the number of transmission stops by CSMA / CA are not included in the frame in the response signal standard, the response signal It is desirable to store in the Vender Specific area.

Further, the communication terminal 100 according to the second embodiment of the present invention differs in information stored in the flash memory 110 of the communication terminal 100 according to the first embodiment and the operation of the CPU 130.
The parameter storage unit 112 of the flash memory 110 stores an electric field strength threshold, a retransmission count threshold, a transmission stop count threshold, and a transmission stop multi-time weight in addition to the parameters stored in the parameter storage unit 112 of the first embodiment. .
The electric field strength threshold is a threshold for determining whether or not the electric field strength of the response signal is sufficiently strong in communication. The retransmission count threshold is a threshold for determining whether or not the response signal retransmission count is excessive. The transmission stop count threshold is a threshold for determining whether or not the number of transmission stops by CSMA / CA of the response signal is excessive. The transmission stop multi-time weight is a weight that is multiplied by the standby extension time stored in the RAM 140 when the number of transmission stops by the CSMA / CA of the response signal is excessive. Note that the transmission stop multi-time weight is a value of 1 or more.

Next, the operation of the communication terminal 100 according to the second embodiment will be described.
FIG. 4 is a diagram illustrating the operation of the communication terminal according to the second embodiment. In addition, the step which performs the same operation | movement as 1st Embodiment is demonstrated using the same step number.
When the communication terminal 100 starts an active scan process by a user operation, the CPU 130 reads the control program from the control program storage unit 111 of the flash memory 110 to the RAM 140 and executes it.

When executing the control program, the CPU 130 initializes the values of the parameters used for the control program stored in the RAM 140 to “0” (step S1).
Next, the CPU 130 outputs a request signal to the conversion unit 121 of the wireless LAN unit 120. The converter 121 converts the input request signal into a radio signal and outputs it to the transmitter 122. The transmission unit 122 transmits the input request signal for the wireless band to the access point 200 (step S2). At this time, the receiving unit 123 starts waiting for a response signal from the access point 200 (step S3). At this time, the time measuring unit 133 of the CPU 130 starts measuring the elapsed time from the time when the transmission unit 122 transmits the request signal, and records it in the elapsed time after transmission stored in the RAM 140 (step S4).

Next, the time measuring unit 133 determines whether or not the post-transmission elapsed time stored in the RAM 140 is equal to or less than the minimum reception standby time stored in the parameter storage unit 112 of the flash memory 110 (step S5).
When the time measuring unit 133 determines that the elapsed time after transmission is equal to or less than the minimum reception standby time (step S5: YES), the reception interval calculating unit 131 determines whether the receiving unit 123 has received a response signal from the access point 200. Is determined (step S6). When the receiving unit 123 has not received the response signal (step S6: NO), the process returns to step S5, and the elapsed time after transmission is compared with the minimum reception standby time.

On the other hand, when the reception unit 123 receives the response signal (step S6: YES), the conversion unit 121 converts the response signal in the radio band into a baseband signal and outputs it to the CPU 130. The reception interval calculation unit 131 of the CPU 130 reads out the electric field strength from the response signal, and determines whether the electric field strength exceeds the electric field strength threshold stored in the parameter storage unit 112 of the flash memory 110 (step S21). . When the reception interval calculation unit 131 determines that the electric field intensity is equal to or less than the electric field intensity threshold (step S21: NO), the process returns to step S5, and the post-transmission elapsed time is compared with the minimum reception standby time.
As described above, when the reception interval calculation unit 131 determines that the radio wave from the access point 200 is weak, the reception interval calculation unit 131 is removed from the calculation target of the reception standby time calculation process, whereby the process can be simplified. In addition, this makes it possible to ignore a response signal from the access point 200 that is likely to be outside the connection range when actually connecting.

  On the other hand, when the reception interval calculation unit 131 determines that the electric field strength exceeds the electric field strength threshold (step S21: YES), a second reception standby time calculation process is executed (step S22). The second reception waiting time extension process is a process of extending and rewriting the reception waiting time of the RAM 140 based on the number of retransmissions and the number of transmission stops by CSMA / CA.

Here, the operation of the second reception standby time calculation process in step S22 will be described.
FIG. 5 is a flowchart showing the operation of the second reception standby time calculation process. In addition, the step which performs the same operation | movement as the reception waiting time calculation process demonstrated in 1st Embodiment is demonstrated using the same step number.
When the CPU 130 starts the second reception standby time calculation process, the reception interval calculation unit 131 reads the number of retransmissions from the response signal, and the number of retransmissions exceeds the retransmission number threshold stored in the parameter storage unit 112 of the flash memory 110. Whether or not (step S201). When the reception interval calculation unit 131 determines that the number of retransmissions exceeds the retransmission number threshold (step S201: YES), the standby time extension unit 132 sets the parameter storage unit 112 of the flash memory 110 to the reception standby time stored in the RAM 140. Is stored (step S202), and the second reception standby time calculation process is terminated.

  In this way, when the number of retransmissions exceeds the retransmission number threshold, the reception standby time is extended to the maximum reception standby time, so that the calculation of intention can be omitted and the processing can be simplified. This also increases the waiting time for response signals when there is a high probability that there are multiple sudden noise sources in the vicinity due to short-range wireless communication and there is a high possibility that the reception conditions for response signals are extremely poor. Can do.

On the other hand, if the reception interval calculation unit 131 determines that the number of retransmissions is equal to or smaller than the retransmission number threshold (step S201: NO), does the reception interval calculation unit 131 indicate “0” as the previous reception time stored in the RAM 140? It is determined whether or not (step S101).
When the reception interval calculation unit 131 determines that the previous reception time indicates “0” (step S101: YES), the standby time extension unit 132 sets the parameter storage unit of the flash memory 110 to the standby extension time stored in the RAM 140. The value of the extended reference time stored in 112 is written (step S102).

  On the other hand, if the reception interval calculation unit 131 determines that the previous reception time does not indicate “0” (step S101: NO), the value obtained by subtracting the previous reception time from the post-transmission elapsed time stored in the RAM 140. Is written in the RAM 140 as a reception interval (step S103). Next, the standby time extension unit 132 reads the number of transmission suspensions by CSMA / CA from the response signal, and determines whether the number of transmission suspensions exceeds the transmission suspension number threshold stored in the parameter storage unit 112 of the flash memory 110. Determination is made (step S203).

When the standby time extension unit 132 determines that the transmission stop count is equal to or less than the transmission stop count threshold (step S203: NO), the extension stored in the parameter storage unit 112 of the flash memory 110 is the same as in the first embodiment. The reference time is divided by the reception interval stored in the RAM 140, and the obtained value is written in the RAM 140 as the standby extension time (step S104).
On the other hand, when the standby time extension unit 132 determines that the transmission stop count exceeds the transmission stop count threshold value (step S203: YES), the RAM 140 stores the extension reference time stored in the parameter storage unit 112 of the flash memory 110. The value divided by the interval is multiplied by the transmission stop multi-time weight stored in the parameter storage unit 112 of the flash memory 110. Then, the obtained value is written in the RAM 140 as the standby extension time (step S204).

  As described above, when the transmission stop count is larger than the transmission stop count threshold, the response signal is kept waiting for a longer time than when the transmission stop count is small. Thereby, the communication terminal 100 can receive response signals from many access points when there is a high possibility that there are many access points.

  When calculating the standby extension time in step S102, step S104, or step S204, the standby time extension unit 132 adds the standby extension time to the elapsed time after transmission stored in the RAM 140, and stores the obtained value in the RAM 140 as the reception standby time. Write (step S105). Next, the standby time extension unit 132 rewrites the previous reception time stored in the RAM 140 with a value indicating the elapsed time after transmission (step S106), and ends the second reception standby time calculation process.

  When the reception standby time calculation process in step S22 is completed (FIG. 4), the time measuring unit 133 of the CPU 130 determines whether the reception standby time stored in the RAM 140 exceeds the minimum reception standby time stored in the parameter storage unit 112 of the flash memory 110. It is determined whether or not (step S8). When the time measuring unit 133 determines that the reception standby time is equal to or less than the minimum reception standby time (step S8: NO), the process returns to step S5, and the post-transmission elapsed time is compared with the minimum reception standby time.

On the other hand, when the timer 133 determines that the reception standby time exceeds the minimum reception standby time (step S8: YES), the maximum reception standby time stored in the parameter storage unit 112 of the flash memory 110 and the reception standby stored in the RAM 140 are stored. The time indicating the shorter time is read out (step S9).
Next, the timer 133 determines whether or not the elapsed time after transmission stored in the RAM 140 is equal to or shorter than the time read in Step S9 (Step S10).

  When the time measuring unit 133 determines that the elapsed time after transmission is equal to or shorter than the time read in step S9 (step S10: YES), the reception interval calculation unit 131 has received the response signal from the access point 200 by the reception unit 123 It is determined whether or not (step S11). If the reception unit 123 has not received a response signal (step S11: NO), the process returns to step S9, and the reception standby time or the maximum reception standby time is compared with the elapsed time after transmission.

  On the other hand, when the reception unit 123 receives the response signal (step S11: YES), the conversion unit 121 converts the response signal in the radio band into a baseband signal and outputs it to the CPU 130. Then, the reception interval calculation unit 131 of the CPU 130 reads out the electric field strength from the response signal and determines whether or not the electric field strength exceeds the electric field strength threshold stored in the parameter storage unit 112 of the flash memory 110 (step S23). . When the reception interval calculation unit 131 determines that the electric field strength is equal to or less than the electric field strength threshold (step S23: NO), the process returns to step S9, and the reception standby time or the maximum reception standby time is compared with the elapsed time after transmission. .

  On the other hand, when it is determined that the electric field strength exceeds the electric field strength threshold (step S23: YES), the reception interval calculation unit 131 reads the standby time maximization flag from the RAM 140, and the standby time maximization flag indicates “ON”. It is determined whether or not (step S12). When the reception interval calculation unit 131 determines that the standby time maximization flag indicates “ON” (step S12: NO), the process returns to step S9, and the reception standby time or the maximum reception standby time is compared with the post-transmission elapsed time. I do.

On the other hand, when the reception interval calculation unit 131 determines that the standby time maximization flag indicates “OFF” (step S12: YES), the CPU 130 executes the second reception standby time calculation process described in step S22. (Step S24).
When the second reception standby time calculation process is completed, the time measuring unit 133 of the CPU 130 determines whether or not the reception standby time stored in the RAM 140 is equal to or greater than the maximum reception standby time stored in the parameter storage unit 112 of the flash memory 110. Determination is made (step S14). When the timer 133 determines that the reception standby time is less than the maximum reception standby time (step S14: NO), the process returns to step S9, and the reception standby time is compared with the elapsed time after transmission.

On the other hand, when it is determined that the reception standby time is equal to or longer than the maximum reception standby time (step S14: YES), the time measuring unit 133 rewrites the standby time maximization flag stored in the RAM 140 to “ON” (step S15), step Returning to S9, the maximum reception standby time is compared with the elapsed time after transmission.
When the time measuring unit 133 determines in step S5 that the elapsed time after transmission exceeds the minimum reception standby time (step S5: NO), or in step S10, the elapsed time after transmission exceeds the time read in step S9. (Step S10: NO), the timer 133 outputs a reception standby end signal to the receiver 123. Next, the reception unit 123 inputs a reception standby end signal, and ends the reception standby process (step S16).
When the reception unit 123 ends the reception standby process, the communication terminal 100 ends the active scan process.

Thus, according to the present embodiment, the communication terminal 100 ignores the response signal when the electric field strength of the response signal is extremely weak. As a result, a response signal from the access point 200 that may be out of the connection range when actually connecting can be prevented from being treated as valid information.
In addition, when the number of retransmissions of the response signal is excessive, the communication terminal 100 increases the response signal standby time. Thereby, even when there is a high possibility that there are a plurality of sudden noise sources in the vicinity due to short-range wireless communication or the like, it is possible to reduce missed response signals.
Further, when the number of transmission stops by CSMA / CA is excessive, the communication terminal 100 lengthens the response signal waiting time. Thereby, when there is a high possibility that there are many access points, response signals from many access points can be received.

As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to
For example, in the first embodiment and the second embodiment, when the reception standby time is longer than the maximum reception standby time, the reception unit 123 waits from the time when the transmission unit 122 transmits the request signal to the maximum reception standby time. The case of waiting for reception of a response signal from the access point 200 has been described, but the present invention is not limited to this. For example, when the reception standby time is longer than the minimum reception standby time, the reception unit 123 does not depend on the maximum reception standby time, and from the time when the transmission unit 122 transmits the request signal to the reception standby time, You may make it wait for reception of a response signal. In this case, the communication terminal 100 loses the advantage that it can save power without prolonging standby for reception, but receives more response signals when there are many access points 200 or when there is a lot of noise. Can do.

  In the first embodiment and the second embodiment, in order to reduce the amount of calculation, the standby extension time is calculated by subtraction and division in the reception standby time calculation process and the second reception standby time calculation process. Although described above, the present invention is not limited to this, and when the CPU 130 is high speed, the reception time of the response signal may be defined as a function, and the standby extension time may be calculated from the differential value.

In the second embodiment, the case where the processing is performed by reading the electric field strength from the information included in the response signal has been described. However, the present invention is not limited to this, and the communication terminal 100 detects the physical electric field strength, Processing may be performed using the detected electric field strength.
In the second embodiment, a constant is used as the transmission stop multi-time weight. However, the constant is not limited to this. For example, the transmission stop multi-time weight is determined based on the difference from the number of transmission stop included in the previously received response signal. By calculating, finer control of the standby extension time may be performed.

  The communication terminal 100 described above has a computer system inside. The operation of each processing unit described above is stored in a computer-readable recording medium in the form of a program, and the above processing is performed by the computer reading and executing this program. 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.

  The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

  DESCRIPTION OF SYMBOLS 100 ... Communication terminal 110 ... Flash memory 111 ... Control program memory | storage part 112 ... Parameter memory | storage part 120 ... Wireless LAN part 121 ... Conversion part 122 ... Transmission part 123 ... Reception part 130 ... CPU 131 ... Reception interval calculation part 132 ... Standby time extension Unit 133: Timekeeping unit 140 ... RAM 150 ... Display unit 160 ... Key input unit 200 ... Access point

Claims (7)

A communication terminal that connects to an access point by active scanning,
A transmission unit for transmitting a request signal;
A standby time storage unit for storing a reception standby time indicating a time until the standby for reception of a response signal from the access point is terminated;
Among the predetermined minimum reception waiting time indicating the minimum time for waiting for reception of the response signal from the time when the transmission unit transmits the request signal, and the reception waiting time stored in the standby time storage unit A reception unit that waits for reception of a response signal in response to a request signal transmitted by the transmission unit from the access point until the time indicated by the longer time is indicated;
A reception interval calculation unit for calculating a reception interval between two consecutive response signals received by the reception unit last;
The shorter the reception interval calculated by the reception interval calculation unit, the longer the standby time extension unit rewrites the reception standby time stored in the standby time storage unit, and
A communication terminal comprising: When the reception standby time stored in the standby time storage unit is longer than the minimum reception standby time, the reception unit is configured to continue to wait for reception of the response signal from the time when the transmission unit transmits a request signal. The response signal responding to the request signal transmitted from the access point from the access point until the time indicated by the shorter time of the predetermined maximum reception standby time indicating the limited time and the reception standby time. The communication terminal according to claim 1, wherein the communication terminal waits for reception. The response signal includes the number of retransmissions of the response signal,
The standby time extension unit reads the number of retransmissions from the response signal received by the reception unit, and when the number of retransmissions is greater than a predetermined threshold, the standby time storage unit stores the reception standby time stored in the maximum reception standby The communication terminal according to claim 2, wherein the communication terminal is rewritten in time. The response signal includes the number of times the response signal is stopped due to carrier sense,
The standby time extension unit reads the number of transmission stops from the response signal received by the reception unit, and rewrites the reception standby time stored in the standby time storage unit to a longer time as the read transmission stop frequency indicates a higher value. The communication terminal according to any one of claims 1 to 3, wherein: The reception interval calculation unit extracts a response signal having an electric field strength larger than a predetermined threshold from the response signal received by the reception unit, and among the extracted response signals, two consecutive responses received by the reception unit last The communication terminal according to any one of claims 1 to 4, wherein a signal reception interval is calculated. Reception standby method using a communication terminal provided with a standby time storage unit for storing a reception standby time indicating a time until connection with an access point by active scan and completion of reception of a response signal from the access point is completed Because
The transmitter transmits a request signal,
The reception unit is configured to store the reception standby stored in the standby time storage unit and a predetermined minimum reception standby time indicating a minimum time for continuing standby for reception of the response signal from the time when the transmission unit transmits the request signal. Waiting for reception of a response signal in response to a request signal transmitted from the access point from the access point until the time indicated by the longer time is indicated.
The reception interval calculation unit calculates a reception interval between two consecutive response signals received by the reception unit last,
The reception standby method, wherein the standby time extension unit rewrites the reception standby time stored in the standby time storage unit to a longer time as the reception interval calculated by the reception interval calculation unit is shorter. A communication terminal provided with a standby time storage unit for storing a reception standby time indicating a time until connection with an access point by active scan and completion of reception of a response signal from the access point is completed,
A transmission unit for transmitting a request signal;
Among the predetermined minimum reception waiting time indicating the minimum time for waiting for reception of the response signal from the time when the transmission unit transmits the request signal, and the reception waiting time stored in the standby time storage unit A reception unit that waits for reception of a response signal in response to a request signal transmitted by the transmission unit from the access point until the time indicated by the longer one,
A reception interval calculation unit for calculating a reception interval between two consecutive response signals received by the reception unit last;
The program for functioning as a waiting time extension part which rewrites the reception waiting time which the waiting time storage part memorizes into a long time, so that the receiving interval which the receiving interval calculation part computed is short.

Images