JP2010239176A - Radio access point, and radio communication control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress increase in processing load caused by data retransmission in a radio access point. <P>SOLUTION: A number of retransmission calculator 15C counts the number of radio terminals 20 under communication with the own terminal by radio communication among radio terminals 20, and calculates the maximum number of retransmission corresponding to the number of terminals during the communication based on relation between the number of terminals during the communication and the maximum number of retransmission. Wherein, in the relation, the maximum number of retransmission becomes a constant maximum number of retransmission after the maximum number of retransmission decreases monotonously according to increase in the number of terminals during the communication. When data are resent to a radio terminal 20 if an acknowledgement for the data transmitted to the radio terminal 20 cannot be received from the radio terminal 20, a retransmission controller 15B ends retransmission of the data if the number of retransmission of the data reaches the maximum number of retransmission. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radio communication technique, and more particularly to a radio communication control technique for controlling data retransmission between a radio access point and a radio terminal.

In a wireless communication system such as a wireless LAN, when data communication is performed between a host device and a plurality of wireless terminals, a wireless access point is installed to perform wired data communication with the host device and wireless data communication with each wireless terminal. And relay connection.
In such a wireless access point, a reception confirmation (ACK) from a wireless terminal indicating normal reception of transmitted data may not be received due to factors such as changes in radio wave conditions, that is, a transmission error may occur.

When such a transmission error occurs, a technique for reducing an increase in the load on the host device due to data retransmission by performing data retransmission with a retransmission device separate from the host device instead of performing data retransmission from the host device Has been proposed (see, for example, Patent Document 1).
Conventionally, some wireless access points are equipped with such a data retransmission function and efficiently process transmission errors in a wireless communication section where a transmission error has occurred.

JP-A-4-273737

However, in such a conventional technique, when a transmission error occurs, the processing load at the wireless access point increases, which affects relay processing for other wireless terminals that are normally performing wireless data communication. There was a problem. For this reason, it is necessary to increase the processing capability of the wireless access point or limit the number of wireless terminals that can be connected to the wireless access point in advance, which increases the cost of the entire wireless communication system.
The present invention has been made to solve such problems, and an object of the present invention is to provide a wireless communication control technique capable of suppressing an increase in processing load at a wireless access point due to data retransmission.

  In order to achieve such an object, a wireless access point according to the present invention includes a wireless interface unit that performs wireless communication by individually connecting to a plurality of wireless terminals, and data received from a host device. A wireless access point including a relay transfer processing unit that relays and forwards data received from a wireless terminal to a higher-level device by wirelessly relaying to the host device, and affirms the data transmitted to the wireless terminal from the wireless terminal If a response cannot be received, the retransmission control unit that retransmits the data, and the number of wireless terminals that are communicating with itself by wireless communication among wireless terminals are counted, and the maximum number of retransmissions according to the increase in the number of communicating terminals Based on the relationship between the number of communicating terminals and the maximum number of retransmissions, which becomes a fixed maximum number of retransmissions after the monotonic decrease, the maximum number of retransmissions corresponding to the number of communicating terminals is calculated. And a retransmission number calculation unit that, the retransmission control unit, the number of retransmissions of the data is completed retransmission of the data when it reaches the maximum number of retransmissions.

  In this case, the retransmission number calculation unit measures the accumulated data amount of data transmitted / received to / from each wireless terminal per unit measurement period, and the wireless terminal in which the accumulated data amount is greater than or equal to the reference value May be counted as the number of communicating terminals.

  In addition, another wireless access point according to the present invention includes a wireless interface unit that performs wireless communication by individually connecting to a plurality of wireless terminals, and relays and transfers data received from a host device to the wireless terminal by wireless communication If the wireless access point includes a relay transfer processing unit that relays and forwards data received by wireless communication from the wireless terminal to the host device and cannot receive an acknowledgment from the wireless terminal for the data transmitted to the wireless terminal, A retransmission control unit that retransmits the data and confirms whether or not the type of data to be retransmitted is audio data. If the data is audio data, the maximum number of retransmissions is smaller than the maximum number of retransmissions for cases other than audio data The retransmission control unit terminates retransmission of the data when the number of retransmissions of data reaches the maximum number of retransmissions.

  In addition, another wireless access point according to the present invention includes a wireless interface unit that performs wireless communication by individually connecting to a plurality of wireless terminals, and relays and transfers data received from a host device to the wireless terminal by wireless communication If the wireless access point includes a relay transfer processing unit that relays and forwards data received by wireless communication from the wireless terminal to a higher-level device and cannot receive an acknowledgment from the wireless terminal for data transmitted to the wireless terminal, The retransmission control unit that performs retransmission of the data and the number of wireless terminals that are connected to the wireless terminal by wireless communication are counted, and after the maximum number of retransmissions monotonously decreases as the number of connected terminals increases, Based on the relation between the number of connected terminals and the maximum number of retransmissions, which is the maximum number of retransmissions, the maximum number of retransmissions corresponding to the number of connected terminals is calculated. And a section, the retransmission control unit, the number of retransmissions of the data is completed retransmission of the data when it reaches the maximum number of retransmissions.

  The wireless communication control method according to the present invention includes a wireless interface unit that performs wireless communication by individually connecting to a plurality of wireless terminals, and relays and transfers data received from a host device to the wireless terminal by wireless communication. A wireless communication control method used in a wireless access point including a relay transfer processing unit that relays and forwards data received by wireless communication from a wireless terminal to a host device, wherein the retransmission control unit responds to data transmitted to the wireless terminal When the acknowledgment from the wireless terminal cannot be received, the retransmission control step for retransmitting the data and the retransmission number calculation unit count the number of wireless terminals that are communicating with the wireless terminal by wireless communication. Based on the relationship between the number of terminals in communication and the maximum number of retransmissions, the maximum number of retransmissions is constant after the maximum number of retransmissions monotonously decreases as the number of medium terminals increases. And a retransmission count calculation step of calculating the maximum number of retransmissions corresponding to the middle number of terminals, in the retransmission control step, the number of retransmissions of the data is completed retransmission of the data when it reaches the maximum number of retransmissions.

  At this time, in the retransmission count calculation step, the accumulated data amount of data transmitted / received to / from each wireless terminal is measured per unit measurement period, and the wireless terminal in which the accumulated data amount is greater than or equal to the reference value May be counted as the number of communicating terminals.

  In addition, another wireless communication control method according to the present invention includes a wireless interface unit that performs wireless communication by individually connecting to a plurality of wireless terminals, and relays data received from a host device to the wireless terminal by wireless communication. A wireless communication control method used in a wireless access point including a relay transfer processing unit that transfers and relays data received from a wireless terminal by wireless communication to a host device, wherein the retransmission control unit transmits the data to the wireless terminal If an acknowledgment from the wireless terminal for the data cannot be received, a retransmission control step for retransmitting the data and a retransmission number calculation unit confirm whether the type of data to be retransmitted is audio data, and the data is audio data In this case, a retransmission number calculation step using a maximum number of retransmissions smaller than the maximum number of retransmissions in the case other than voice data is included, and the retransmission control step includes Number of retransmissions of data is completed retransmission of the data when it reaches the maximum number of retransmissions.

  In addition, another wireless communication control method according to the present invention includes a wireless interface unit that performs wireless communication by individually connecting to a plurality of wireless terminals, and relays data received from a host device to the wireless terminal by wireless communication. A wireless communication control method used in a wireless access point including a relay transfer processing unit that transfers and relays data received from a wireless terminal by wireless communication to a host device, wherein the retransmission control unit transmits the data to the wireless terminal When an acknowledgment from the wireless terminal for data cannot be received, a retransmission control step for retransmitting the data and a retransmission number calculation unit count the number of wireless terminals connected to the wireless terminal by wireless communication. Based on the relationship between the number of connected terminals and the maximum number of retransmissions, which becomes a fixed maximum number of retransmissions after the maximum number of retransmissions monotonously decreases as the number of connected terminals increases. Te, and a retransmission count calculation step of calculating the maximum number of retransmissions corresponding to the number of the connection terminals, in the retransmission control step, the number of retransmissions of the data is completed retransmission of the data when it reaches the maximum number of retransmissions.

  ADVANTAGE OF THE INVENTION According to this invention, the frequency | count of resending of the data in a wireless access point can be suppressed according to the communication condition between a wireless access point and a wireless terminal. As a result, an increase in processing load at the wireless access point due to data retransmission can be suppressed.

It is a block diagram which shows the structure of the wireless access point concerning the 1st Embodiment of this invention. It is explanatory drawing which shows the frequency | count calculation of retransmissions concerning the 1st Embodiment of this invention. It is a flowchart which shows the frequency | count calculation of resending concerning the 1st Embodiment of this invention. It is a flowchart which shows the resending control process concerning the 1st Embodiment of this invention. It is a sequence diagram which shows the operation example of the wireless access point concerning the 1st Embodiment of this invention. It is explanatory drawing which shows the retransmission count calculation information concerning the 2nd Embodiment of this invention. It is a flowchart which shows the frequency | count calculation of retransmissions concerning the 2nd Embodiment of this invention. It is a flowchart which shows the resending control process concerning the 2nd Embodiment of this invention. It is a sequence diagram which shows the operation example of the radio | wireless access point concerning the 2nd Embodiment of this invention. It is explanatory drawing which shows the retransmission count calculation information concerning the 3rd Embodiment of this invention. It is a flowchart which shows the retransmission count calculation process concerning the 3rd Embodiment of this invention. It is a sequence diagram which shows the operation example of the wireless access point concerning the 3rd Embodiment of this invention.

Next, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
First, a wireless access point according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a wireless access point according to the first embodiment of the present invention.
The wireless access point 10 individually connects to a plurality of wireless terminals 20 to perform wireless communication, and relays and transfers data received from the host device 30 to the wireless terminal 20 by wireless communication. It has a function of relaying and transferring data received by wireless communication to the host device 30.

  In the present embodiment, the wireless access point 10 counts the number of wireless terminals 20 communicating with itself by wireless communication among the wireless terminals 20, and the maximum number of retransmissions monotonously decreases as the number of communicating terminals increases. After that, based on the relationship between the number of communicating terminals and the maximum number of retransmissions, which becomes a certain maximum number of retransmissions, the maximum number of retransmissions corresponding to the number of communicating terminals is calculated, and the wireless for the data transmitted to the wireless terminal 20 When retransmission of the data is performed when an acknowledgment from the terminal 20 cannot be received, the retransmission of the data is terminated when the number of retransmissions of the data reaches the maximum number of retransmissions.

[Wireless access point]
Next, the configuration of the wireless access point according to the present embodiment will be described in detail with reference to FIG.
The wireless access point 10 includes, as main functional units, a communication interface unit (hereinafter referred to as a communication I / F unit) 11, a data buffer 12, a wireless interface unit (hereinafter referred to as a wireless I / F unit) 13, and a storage unit 14. And a control unit 15 are provided.

The communication I / F unit 11 includes a dedicated communication circuit, and has a function of performing data communication with the host device 30.
The data buffer 12 includes a storage device such as a semiconductor memory, and has a function of temporarily storing data received from the host device 30 and the wireless terminal 20.
The wireless I / F unit 13 includes a dedicated wireless circuit and has a function of performing wireless data communication with the wireless terminal 20.

The storage unit 14 includes a storage device such as a semiconductor memory, and has a function of storing processing information and programs used in various processes in the control unit 15.
The main processing information stored in the storage unit 14 is retransmission count calculation information 14A. FIG. 2 is an explanatory diagram illustrating retransmission count calculation information according to the first embodiment of the present invention, where the horizontal axis indicates the number of communicating terminals, and the vertical axis indicates the maximum number of retransmissions relative to the number of communicating terminals. Yes. This retransmission count calculation information 14A shows the relationship between the number of terminals in communication and the maximum number of retransmissions, which becomes a fixed maximum number of retransmissions after the maximum number of retransmissions monotonously decreases with an increase in the number of terminals in communication. Used to calculate the number of retransmissions to be performed. Note that the retransmission count calculation information 14A may be expressed by a functional expression or a table.

The control unit 15 includes a microprocessor such as a CPU and its peripheral circuits, and has a function of realizing various processing units by executing a program read from the storage unit 14.
As main processing units realized by the control unit 15, there are a relay transfer processing unit 15A, a retransmission control unit 15B, and a retransmission number calculation unit 15C.

  The relay transfer processing unit 15A temporarily stores the data received from the higher-level device 30 via the communication I / F unit 11 in the data buffer 12, and wirelessly communicates with the wireless terminal 20 designated as the destination of the data by wireless communication. The function of relay transfer through the F unit 13 and the data received from the wireless terminal 20 via the wireless I / F unit 13 by wireless communication are temporarily stored in the data buffer 12, and the host device designated as the destination of the data 30 and a function of relaying and transferring to 30 via the communication I / F unit 11.

  When the relay transfer processing unit 15A cannot receive an acknowledgment (ACK) from the wireless terminal 20 with respect to the data transmitted to the wireless terminal 20 within a specified time from the transmission of the data, the retransmission control unit 15B receives the data buffer 12 A function of resending the data stored in the wireless terminal 20 from the wireless I / F unit 13 and a function of terminating the retransmission of the data when the number of retransmissions of the data reaches the maximum number of retransmissions. have.

  The retransmission number calculation unit 15C has a function of counting the number of wireless terminals 20 communicating with its own wireless access point 10 by wireless communication among the wireless terminals 20, and the maximum number of retransmissions according to the increase in the number of communicating terminals. A function for calculating the maximum number of retransmissions corresponding to the number of terminals in communication based on retransmission number calculation information 14A indicating the relationship between the number of terminals in communication and the maximum number of retransmissions, which becomes a fixed maximum number of retransmissions after monotonously decreasing; have.

  The maximum number of retransmissions is a value indicating the maximum number of retransmissions of arbitrary data that has caused a transmission error. On the other hand, the number of terminals in communication is the number of wireless terminals 20 communicating with its own wireless access point 10. Some of the wireless terminals 20 have established communication links with the wireless access point 10 but do not actually transmit or receive data. In the present embodiment, the number of retransmissions calculation unit 15C measures the accumulated data amount of data transmitted / received to / from each wireless terminal 20 per unit measurement period, and the accumulated data amount of these wireless terminals 20 is used as a reference. The number of wireless terminals 20 that are equal to or greater than the value is counted as the number of communicating terminals.

[Operation of First Embodiment]
Next, the operation of the wireless access point according to the present embodiment will be described with reference to FIG. 3 and FIG. FIG. 3 is a flowchart showing a retransmission count calculation process according to the first embodiment of the present invention. FIG. 4 is a flowchart showing a retransmission control process according to the first embodiment of the present invention. Here, the retransmission number calculation process and the retransmission control process will be described in detail as operations of the wireless access point according to the present embodiment.

[Retransmission count calculation processing]
The retransmission count calculation unit 15C executes the retransmission count calculation process of FIG. 3 in parallel with the relay transfer process by the relay transfer processing unit 15A.
First, the retransmission number calculation unit 15C uses a timer function provided in advance in the control unit (CPU) to start a measurement period timer for measuring a predetermined measurement period (step 100). For example, referring to the data buffer 12, until the measurement period timer expires (step 102: NO), the accumulated data amount of other data transmitted / received to / from the wireless terminal 20 is measured for each wireless terminal 20 (step 102). 101).

Thereafter, in response to the time-up of the measurement period timer (step 102: YES), the retransmission number calculation unit 15C starts a wireless terminal loop (step 110) and repeatedly executes steps 111 to 113 for each wireless terminal 20. .
In the wireless terminal loop (step 110), first, the number-of-retransmissions calculation unit 15C compares the accumulated data amount of the wireless terminal 20 with a reference value (step 111), and when the accumulated data amount is greater than or equal to the reference value (step 111). : YES), it is determined that the wireless terminal 20 is in communication (step 112), and the accumulated data amount has not reached the reference value (step 111: NO), the wireless terminal 20 is in communication (Step 113).

The retransmission number calculation unit 15 </ b> C ends the wireless terminal loop 110 after determining such a communication state for each wireless terminal 20, and determines that the wireless terminal 20 is in a communication state based on these determinations. The number of wireless terminals 20 is counted as the number of communicating terminals (step 103).
Thereafter, the retransmission number calculation unit 15C calculates the maximum number of retransmissions corresponding to the number of communicating terminals based on the retransmission number calculation information 14A in the storage unit 14 and stores it in the storage unit 14 (step 104). Returning to 100, the retransmission count calculation process based on the next counting period is started.
As a result, a new maximum number of retransmissions is calculated for each counting period and stored in the storage unit 14.

[Retransmission control processing]
The retransmission control unit 15B starts the retransmission control in FIG. 4 when data transmission to the wireless terminal 20 is performed by the relay transfer processing unit 15A.
First, the retransmission control unit 15B sends an acknowledgment (ACK) from the wireless terminal 20 that is the destination of the data via the wireless I / F unit 13 until a predetermined time has elapsed since the data transmission. It is confirmed whether or not it has been received (step 120). For the measurement of the specified time, a timer function provided in advance in the control unit (CPU) may be used as in the measurement period described above.

Here, if an affirmative response is received within the specified time (step 120: YES), the retransmission control unit 15B ends a series of retransmission control for the data.
On the other hand, if an affirmative response has not been received within the specified time (step 120: NO), the retransmission control unit 15B initializes the number of retransmissions of the data to zero (step 121) and is stored in the data buffer 12. The data is retransmitted from the wireless I / F unit 13 to the wireless terminal 20 (step 122).

Thereafter, the retransmission control unit 15B adds 1 to the number of retransmissions of the data (step 123), and from the wireless terminal 20 that is the destination of the data until a predetermined time has elapsed since the data retransmission. Then, it is confirmed whether or not an acknowledgment (ACK) has been received via the wireless I / F unit 13 (step 124).
Here, when an affirmative response is received within the specified time (step 124: YES), the retransmission control unit 15B ends a series of retransmission control for the data.

On the other hand, if the acknowledgment is not received within the specified time (step 124: NO), the retransmission control unit 15B reads the maximum number of retransmissions calculated by the retransmission number calculation unit 15C from the storage unit 14 and retransmits the data. The number of times is compared (step 125).
Here, when the number of retransmissions has not reached the maximum number of retransmissions (step 125: NO), the process returns to step 122 to repeat data retransmission, and when the number of retransmissions reaches the maximum number of retransmissions (step 125: YES), A series of retransmission control for data is terminated.

[Operation Example of First Embodiment]
Next, an operation example of the wireless access point according to the present embodiment will be described with reference to FIG. FIG. 5 is a sequence diagram showing an operation example of the wireless access point according to the first embodiment of the present invention.
Here, a case where three wireless terminals 20A to 20C are provided for the wireless access point 10 will be described as an example.

First, when data communication is performed between the host device 30 and the wireless terminal 20A (step 150), the number of terminals in communication is “1” in the wireless access point 10, and the maximum number of retransmissions is set to “4”. (Step 151).
Thereafter, data communication is performed between the host device 30 and the wireless terminal 20B (step 152), and when data communication is performed between the host device 30 and the wireless terminal 20C (step 153), wireless access is performed. At point 10, the number of communicating terminals is “3”, and the maximum number of retransmissions is set to “2” (step 154).

  In such a state, when data addressed to the wireless terminal 20A is transmitted from the host device 30 (step 160), this data is received by the wireless access point 10 and wirelessly transmitted to the wireless terminal 20A (step 161). ). Further, an acknowledgment (ACK) for this data is returned from the radio terminal 20A (step 162) and transferred to the upper level apparatus 30 via the radio access point 10 (step 163).

Subsequently, when the next data addressed to the wireless terminal 20A is transmitted from the host device 30 (step 170), it is wirelessly transmitted from the wireless access point 10 to the wireless terminal 20A in the same manner as described above (step 171). . At this time, if the radio terminal 20A cannot receive the data normally due to the deterioration of the radio wave condition, an acknowledgment for the data is not returned from the radio terminal 20A.
As a result, since the wireless access point 10 has not received an acknowledgment within a specified time from the transmission of the data, retransmission of the data is started.

In the wireless access point 10, first, data retransmission is performed for the first time (step 172), and if the acknowledgment for the first retransmission data is not received within a specified time from the transmission, the second data retransmission is performed. (Step 173).
Here, if an acknowledgment is not received within a specified time from the transmission of the second retransmission data, the number of retransmissions of the data has already reached the maximum number of retransmissions set in step 154, so that the wireless access point 10 Thus, the retransmission of the data is completed (step 174).

[Effect of the first embodiment]
As described above, according to the present embodiment, the number of retransmission times calculation unit 15C counts the number of wireless terminals 20 that are communicating with itself by wireless communication among the wireless terminals 20, and increases the maximum according to the increase in the number of communicating terminals. Based on the relationship between the number of communicating terminals and the maximum number of retransmissions, which becomes a fixed maximum number of retransmissions after the number of retransmissions monotonously decreases, the maximum number of retransmissions corresponding to the number of communicating terminals is calculated, and the retransmission control unit 15B When retransmitting the data when the acknowledgment sent from the wireless terminal 20 to the data transmitted to the wireless terminal 20 cannot be received, the retransmission of the data ends when the number of retransmissions of the data reaches the maximum number of retransmissions. Therefore, the number of data retransmissions at the wireless access point 10 can be suppressed according to the communication status between the wireless access point 10 and the wireless terminal 20. As a result, an increase in processing load at the wireless access point 10 due to data retransmission can be suppressed.

  In this embodiment, the number of communicating terminals is counted based on the accumulated data amount of each wireless terminal 20 measured per unit measurement period, and the maximum number of retransmissions is calculated based on the number of communicating terminals. Even when there is a large variation in the communication data amount for each wireless terminal 20 or when there is a large temporal variation in the communication data amount of any wireless terminal 20, the optimum maximum number of retransmissions at that time can be calculated. .

[Second Embodiment]
Next, a wireless access point according to the second embodiment of the present invention will be described.
In the first embodiment, the case where the number of data retransmissions is calculated according to the number of communicating terminals has been described as an example. In the present embodiment, a case will be described in which the number of retransmissions of the data is calculated according to the data type of the data to be retransmitted.

  In a telephone system such as a button telephone system or a PBX system, the wireless access point 10 is used when the wireless terminal 20 is accommodated as an extension telephone terminal. In this case, of the data relayed and transferred by the wireless access point 10, the amount of audio data is larger than that of other control data, and the processing load at the wireless access point 10 is greatly increased due to retransmission of the audio data. . For this reason, if the maximum number of retransmissions of audio data is set smaller than the maximum number of retransmissions of data other than audio data, an increase in processing load caused by the retransmission of audio data can be suppressed.

  FIG. 6 is an explanatory diagram of retransmission count calculation information according to the second embodiment of the present invention. In the present embodiment, the maximum number of retransmissions related to the data is registered in the retransmission number calculation information 14A of the storage unit 14 for each data type of the data to be retransmitted. Here, “2” is registered as the maximum number of retransmissions for data whose data type is “voice data”, and “4” is registered as the maximum number of retransmissions for data whose data type is “other than voice data”. .

The retransmission number calculation unit 15C according to the present embodiment calculates the maximum number of retransmissions according to the data type from the function of confirming the data type based on the header information of the retransmission data and the retransmission number calculation information 14A of the storage unit 14. It has the function to do.
The retransmission control unit 15B has a function of calculating the maximum number of retransmissions related to the retransmission data by the retransmission number calculation unit 15C when performing data retransmission.
Note that, in the wireless access point according to the present embodiment, configurations other than these are the same as those in the first embodiment, and detailed description thereof is omitted here.

[Operation of Second Embodiment]
Next, the operation of the wireless access point according to the present embodiment will be described with reference to FIGS. FIG. 7 is a flowchart showing a retransmission count calculation process according to the second embodiment of the present invention. FIG. 8 is a flowchart showing a retransmission control process according to the second embodiment of the present invention. Here, the retransmission number calculation process and the retransmission control process will be described in detail as operations of the wireless access point according to the present embodiment.

[Retransmission count calculation processing]
The retransmission number calculation unit 15C executes the retransmission number calculation process of FIG. 7 in response to a request from the retransmission control unit 15B.
First, the retransmission number calculation unit 15C confirms the data type based on the header information of the retransmission data (step 200).
Subsequently, the retransmission number calculation unit 15C refers to the retransmission number calculation information 14A in the storage unit 14, calculates the maximum number of retransmissions according to the data type (step 201), and ends the series of retransmission number calculation processes. .

[Retransmission control processing]
The retransmission control unit 15B starts the retransmission control in FIG. 8 when data transmission to the wireless terminal 20 is performed by the relay transfer processing unit 15A.
First, the retransmission control unit 15B sends an acknowledgment (ACK) from the wireless terminal 20 that is the destination of the data via the wireless I / F unit 13 until a predetermined time has elapsed since the data transmission. It is confirmed whether it has been received (step 210). For the measurement of the specified time, a timer function provided in advance in the control unit (CPU) may be used as in the measurement period described above.

Here, when an affirmative response is received within the specified time (step 210: YES), the retransmission control unit 15B ends a series of retransmission control for the data.
On the other hand, when the acknowledgment is not received within the specified time (step 210: NO), the retransmission control unit 15B executes the retransmission number calculation process by the retransmission number calculation unit 15C, and sets the maximum number of retransmissions related to the retransmission data. Calculate (step 211), initialize the number of retransmissions of the data to zero (step 212), and retransmit the data stored in the data buffer 12 from the wireless I / F unit 13 to the wireless terminal 20 (step 213). ).

Thereafter, the retransmission control unit 15B adds 1 to the number of retransmissions of the data (step 214), and from the wireless terminal 20 that is the destination of the data until a predetermined time has elapsed since the data retransmission. Then, it is confirmed whether or not an acknowledgment (ACK) has been received via the wireless I / F unit 13 (step 215).
Here, if an affirmative response is received within the specified time (step 215: YES), the retransmission control unit 15B ends a series of retransmission control for the data.

On the other hand, when the acknowledgment is not received within the specified time (step 215: NO), the retransmission control unit 15B reads the maximum number of retransmissions calculated by the retransmission number calculation unit 15C from the storage unit 14 and retransmits the data. The number of times is compared (step 216).
Here, when the number of retransmissions has not reached the maximum number of retransmissions (step 216: NO), the process returns to step 122 and data retransmission is repeated, and when the number of retransmissions reaches the maximum number of retransmissions (step 216: YES), A series of retransmission control for data is terminated.

[Operation Example of Second Embodiment]
Next, with reference to FIG. 9, an operation example of the wireless access point according to the present embodiment will be described. FIG. 9 is a sequence diagram illustrating an operation example of the wireless access point according to the second embodiment of the present invention.
Here, a case where three wireless terminals 20A to 20C are provided for the wireless access point 10 will be described as an example.

  First, when voice data addressed to the wireless terminal 20A is transmitted from the host device 30 (step 250), the voice data is received by the wireless access point 10 and wirelessly transmitted to the wireless terminal 20A (step 251). Further, an acknowledgment (ACK) for the voice data is returned from the radio terminal 20A (step 252), and transferred to the higher-level device 30 via the radio access point 10 (step 253).

Subsequently, when the next audio data addressed to the wireless terminal 20A is transmitted from the host device 30 (step 260), it is wirelessly transmitted from the wireless access point 10 to the wireless terminal 20A in the same manner as described above (step 261). ). At this time, if the radio terminal 20A cannot receive the audio data normally due to the deterioration of the radio wave condition, an acknowledgment for the audio data is not returned from the radio terminal 20A.
As a result, since the wireless access point 10 has not received an acknowledgment within a specified time from the transmission of the audio data, retransmission of the audio data is started.

In the wireless access point 10, first, since the retransmission data is voice data, the maximum number of retransmissions is set to “2” (step 262), and the first data retransmission is performed (step 263). If no acknowledgment is received within a specified time from the transmission of the retransmission data, the second data retransmission is performed (step 264).
Here, if an acknowledgment cannot be received within a specified time from the transmission of the second retransmission data, the number of retransmissions of the data has already reached the maximum number of retransmissions set in step 262, and thus the wireless access point 10 Thus, the retransmission of the data is completed (step 265).

On the other hand, when control data addressed to the wireless terminal 20B is transmitted from the host device 30 (step 270), the control data is received by the wireless access point 10 and wirelessly transmitted to the wireless terminal 20B (step 271). At this time, if the control data cannot be normally received by the wireless terminal 20B due to the deterioration of the radio wave condition, an affirmative response to the control data is not returned from the wireless terminal 20B.
Thereby, since the wireless access point 10 has not received an acknowledgment within a specified time from transmission of the control data, retransmission of the control data is started.

  In the wireless access point 10, first, since the retransmission data is control data, the maximum number of retransmissions is set to “4” (step 272), and the first data retransmission is performed (step 273). Here, if an affirmative response can be received within a specified time from the transmission of the first retransmission data (step 274), the retransmission of the data by the wireless access point 10 ends (step 275).

[Effect of the second embodiment]
As described above, in this embodiment, the number of retransmissions calculation unit 15C confirms whether the type of data to be retransmitted is audio data, and if the data is audio data, the maximum retransmission in the case other than audio data Since the maximum number of retransmissions smaller than the number of times is used, the number of retransmissions of audio data having a relatively large amount of data can be suppressed from the number of retransmissions of data other than the audio data. As a result, it is possible to suppress a significant increase in processing load at the wireless access point caused by the retransmission of the voice data.

[Third Embodiment]
Next, a wireless access point according to the third embodiment of the present invention will be described.
In the first embodiment, the case where the number of data retransmissions is calculated according to the number of communicating terminals has been described as an example. In the present embodiment, a case where the number of data retransmissions is calculated according to the number of connected terminals will be described.

  FIG. 10 is an explanatory diagram of retransmission count calculation information according to the third embodiment of the present invention, where the horizontal axis indicates the number of connected terminals and the vertical axis indicates the maximum number of retransmissions for the number of communicating terminals. . In the present embodiment, the retransmission count calculation information 14A in the storage unit 14 includes the number of connected terminals and the maximum number of retransmissions, which become a fixed maximum number of retransmissions after the maximum number of retransmissions monotonously decreases in accordance with the increase in the number of connected terminals. The relationship is shown and used for calculating the number of retransmissions. Note that the retransmission count calculation information 14A may be expressed by a functional expression or a table.

The retransmission number calculation unit 15C according to the present embodiment is configured to count the number of wireless terminals 20 connected to its own wireless access point 10 by wireless communication among the wireless terminals 20, and to increase the number of connected terminals. Corresponding to the number of terminals in communication based on the retransmission number calculation information 14A of the storage unit 14 indicating the relationship between the number of connected terminals and the maximum number of retransmissions, which becomes a constant maximum number of retransmissions after the maximum number of retransmissions monotonously decreases accordingly. And a function for calculating the maximum number of retransmissions to be performed.
Note that, in the wireless access point according to the present embodiment, configurations other than these are the same as those in the first embodiment, and detailed description thereof is omitted here.

[Operation of Third Embodiment]
Next, the operation of the wireless access point according to the present embodiment will be described with reference to FIG. FIG. 11 is a flowchart showing a retransmission count calculation process according to the third embodiment of the present invention. Here, the retransmission count calculation process will be described in detail as the operation of the wireless access point according to the present embodiment. Note that the retransmission control processing according to the present embodiment is the same as that of the first embodiment, and a detailed description thereof is omitted here.

[Retransmission count calculation processing]
The retransmission number calculation unit 15C executes the retransmission number calculation process of FIG. 11 in response to a request from the retransmission control unit 15B.
First, the retransmission number calculation unit 15C determines the number of wireless terminals 20 connected to its own wireless access point 10 based on the connection request or disconnection request from the wireless terminal 20A received by the relay transfer processing unit 15A, that is, The number of connected terminals is counted (step 300).
Subsequently, the retransmission number calculation unit 15C refers to the retransmission number calculation information 14A in the storage unit 14, calculates the maximum number of retransmissions according to the number of connected terminals (step 301), and ends a series of retransmission number calculation processes. To do.

[Operation Example of Third Embodiment]
Next, an operation example of the wireless access point according to the present embodiment will be described with reference to FIG. FIG. 12 is a sequence diagram illustrating an operation example of the wireless access point according to the third embodiment of the present invention.
Here, a case where three wireless terminals 20A to 20C are provided for the wireless access point 10 will be described as an example.

First, when connection processing is performed between the wireless terminal 20A and the wireless access point 10 in response to a connection request from the wireless terminal 20A (step 350), the number of connected terminals is “1” in the wireless access point 10. And the maximum number of retransmissions is set to “3” (step 351).
Subsequently, when a connection process is performed between the wireless terminal 20B and the wireless access point 10 in response to a connection request from the wireless terminal 20B (step 352), the number of connected terminals in the wireless access point 10 is “2”. The maximum number of retransmissions is set to “2” (step 353).

Further, when connection processing is performed between the wireless terminal 20C and the wireless access point 10 in response to a connection request from the wireless terminal 20C (step 354), the number of connected terminals is “3” in the wireless access point 10. And the maximum number of retransmissions is set to “1” (step 355).
Thereafter, when a disconnection process is performed between the wireless terminal 20B and the wireless access point 10 in response to a disconnection request from the wireless terminal 20B (step 356), the number of connected terminals in the wireless access point 10 is “2”. The maximum number of retransmissions is set to “2” (step 357).

  In such a state, when data addressed to the wireless terminal 20A is transmitted from the host device 30 (step 360), this data is received by the wireless access point 10 and wirelessly transmitted to the wireless terminal 20A (step 361). ). Further, an acknowledgment (ACK) for this data is returned from the radio terminal 20A (step 362) and transferred to the host device 30 via the radio access point 10 (step 363).

Subsequently, when the next data addressed to the wireless terminal 20A is transmitted from the host device 30 (step 370), it is wirelessly transmitted from the wireless access point 10 to the wireless terminal 20A in the same manner as described above (step 371). . At this time, if the radio terminal 20A cannot receive the data normally due to the deterioration of the radio wave condition, an acknowledgment for the data is not returned from the radio terminal 20A.
As a result, since the wireless access point 10 has not received an acknowledgment within a specified time from the transmission of the data, retransmission of the data is started.

In the wireless access point 10, first, data retransmission is performed for the first time (step 372), and if the acknowledgment for the first retransmission data is not received within a specified time from the transmission, the second data retransmission is performed. (Step 373).
Here, if an acknowledgment cannot be received within a specified time from the transmission of the second retransmission data, the number of retransmissions of the data has already reached the maximum number of retransmissions set in step 357, and thus the wireless access point 10 Thus, the retransmission of the data ends (step 374).

[Effect of the third embodiment]
As described above, in the present embodiment, the number of retransmission terminals 15C counts the number of wireless terminals 20 that are connected to the wireless terminal 20 by wireless communication, and the maximum number is increased according to the increase in the number of connected terminals. Based on the relationship between the number of connected terminals and the maximum number of retransmissions, which becomes a fixed maximum number of retransmissions after the number of retransmissions monotonously decreases, the maximum number of retransmissions corresponding to the number of communicating terminals is calculated. The number of data retransmissions can be suppressed according to the number of connected terminals. As a result, an increase in processing load at the wireless access point due to data retransmission can be suppressed.

In the first embodiment, the number of terminals in communication is counted based on the accumulated data amount of each wireless terminal 20 measured per unit measurement period, and the maximum number of retransmissions is calculated based on the number of terminals in communication. A certain amount of processing load on the wireless access point 10 is required for the calculation of the data amount.
On the other hand, according to the present embodiment, the number of connected terminals is counted in response to a connection request or a disconnection request to the wireless access point 10 transmitted from the wireless terminal 20 at the start / end of wireless communication. The processing load on the wireless access point 10 can be reduced. Further, according to the present embodiment, the maximum number of retransmissions can be calculated in consideration of the amount of communication data at the wireless terminal 20 that is not actually transmitting / receiving data, and it can cope to some extent with an unexpected increase in the amount of communication data. It becomes possible.

[Extended embodiment]
In the above, the case of using a separate retransmission count calculation process has been described for each embodiment, but the retransmission count calculation process may be combined. When the combination is performed, a weight for the maximum number of retransmissions may be set for each retransmission number calculation method of each embodiment.
At this time, the weight coefficient W is set in accordance with the communication system in which the wireless access point 10 is used so that the sum of the weight counts for the respective embodiments is “1”.

  For example, when combining the first and third embodiments, the weight for the maximum number of retransmissions N1 obtained from the number of communicating terminals according to the first embodiment is set to W1 = 0.6, and the third embodiment A weight for the maximum number of retransmissions N3 obtained from the number of connected terminals is set as W3 = 0.4. Thereby, the maximum number of retransmissions N by these combinations can be obtained by N = N1 × W1 + N3 × W3 every time N1 and N3 are updated. Note that these weights may be multiplied in advance by the retransmission count calculation information 14A. If the maximum number of retransmissions N includes a decimal point, rounding such as rounding may be performed.

  For this reason, the wireless access point 10 which has the effect of each embodiment is realizable. For example, when the first embodiment and the third embodiment are combined, there is a large variation in the amount of communication data for each wireless terminal 20, or there is a large temporal variation in the amount of communication data of any wireless terminal 20. Even when there is an error, it is possible to calculate the optimum maximum number of retransmissions at that time and to cope with a sudden increase in the amount of communication data.

  The combination of the first and second embodiments, the combination of the second and third embodiments, and the combination of the first, second, and third embodiments are the same as described above. Thus, the maximum number of retransmissions can be obtained based on each preset weight coefficient.

  DESCRIPTION OF SYMBOLS 10 ... Wireless access point, 11 ... Communication I / F part, 12 ... Data buffer, 13 ... Wireless I / F part, 14 ... Memory | storage part, 14A ... Retransmission count calculation information, 15 ... Control part, 15A ... Relay transfer process part , 15B ... retransmission control unit, 15C ... retransmission number calculation unit, 20, 20A, 20B, 20C ... wireless terminal, 30 ... host device.

Claims (8)

A wireless interface unit that performs wireless communication by individually connecting to a plurality of wireless terminals, and relays and transfers data received from a host device to the wireless terminal by the wireless communication and receives from the wireless terminal by the wireless communication A wireless access point including a relay transfer processing unit that relays and transfers the received data to the host device,
If an acknowledgment from the wireless terminal for data transmitted to the wireless terminal cannot be received, a retransmission control unit that performs retransmission of the data;
The number of wireless terminals that are communicating with itself by the wireless communication among the wireless terminals is counted, and the maximum number of retransmissions monotonously decreases in accordance with the increase in the number of terminals in communication, and the constant maximum number of retransmissions is being performed. Based on the relationship between the number of terminals and the maximum number of retransmissions, a retransmission number calculating unit that calculates the maximum number of retransmissions corresponding to the number of communicating terminals, and
The wireless access point, wherein the retransmission control unit ends retransmission of the data when the number of retransmissions of the data reaches the maximum number of retransmissions. The wireless access point according to claim 1,
The retransmission number calculation unit measures the accumulated data amount of data transmitted / received to / from each wireless terminal per unit measurement period, and among these wireless terminals, the wireless terminal having the accumulated data amount equal to or greater than a reference value. A wireless access point that counts the number as the number of communicating terminals. A wireless interface unit that performs wireless communication by individually connecting to a plurality of wireless terminals, and relays and transfers data received from a host device to the wireless terminal by the wireless communication and receives from the wireless terminal by the wireless communication A wireless access point including a relay transfer processing unit that relays and transfers the received data to the host device,
If an acknowledgment from the wireless terminal for data transmitted to the wireless terminal cannot be received, a retransmission control unit that performs retransmission of the data;
It is confirmed whether or not the type of data to be retransmitted is voice data, and when the data is voice data, a retransmission number calculation unit that uses a maximum number of retransmissions smaller than the maximum number of retransmissions in cases other than voice data, and
The wireless access point, wherein the retransmission control unit ends retransmission of the data when the number of retransmissions of the data reaches the maximum number of retransmissions. A wireless interface unit that performs wireless communication by individually connecting to a plurality of wireless terminals, and relays and transfers data received from a host device to the wireless terminal by the wireless communication and receives from the wireless terminal by the wireless communication A wireless access point including a relay transfer processing unit that relays and transfers the received data to the host device,
If an acknowledgment from the wireless terminal for data transmitted to the wireless terminal cannot be received, a retransmission control unit that performs retransmission of the data;
A connection terminal that counts the number of wireless terminals that are connected to itself by the wireless communication among the wireless terminals, and that reaches a certain maximum number of retransmissions after the maximum number of retransmissions monotonously decreases as the number of connected terminals increases A retransmission number calculation unit that calculates the maximum number of retransmissions corresponding to the number of connected terminals based on the relationship between the number of connections and the maximum number of retransmissions, and
The wireless access point, wherein the retransmission control unit ends retransmission of the data when the number of retransmissions of the data reaches the maximum number of retransmissions. A wireless interface unit that performs wireless communication by individually connecting to a plurality of wireless terminals, and relays and transfers data received from a host device to the wireless terminal by the wireless communication and receives from the wireless terminal by the wireless communication A wireless communication control method used in a wireless access point including a relay transfer processing unit that relays and transfers the received data to the host device,
When the retransmission control unit cannot receive an acknowledgment from the wireless terminal for the data transmitted to the wireless terminal, a retransmission control step for performing retransmission of the data;
The retransmission number calculation unit counts the number of wireless terminals that are communicating with itself through the wireless communication among the wireless terminals, and the maximum number of retransmissions after the maximum number of retransmissions monotonously decreases in accordance with the increase in the number of communicating terminals. A retransmission number calculating step of calculating a maximum number of retransmissions corresponding to the number of communicating terminals based on the relationship between the number of communicating terminals and the maximum number of retransmissions,
The retransmission control step ends the retransmission of the data when the number of retransmissions of the data reaches the maximum number of retransmissions. The wireless communication control method according to claim 5,
The retransmission count calculating step measures the accumulated data amount of data transmitted / received to / from each wireless terminal per unit measurement period, and of the wireless terminals whose accumulated data amount is greater than or equal to a reference value. A wireless communication control method, wherein a number is counted as the number of communicating terminals. A wireless interface unit that performs wireless communication by individually connecting to a plurality of wireless terminals, and relays and transfers data received from a host device to the wireless terminal by the wireless communication and receives from the wireless terminal by the wireless communication A wireless communication control method used in a wireless access point including a relay transfer processing unit that relays and transfers the received data to the host device,
When the retransmission control unit cannot receive an acknowledgment from the wireless terminal for the data transmitted to the wireless terminal, a retransmission control step for performing retransmission of the data;
The retransmission number calculation unit checks whether or not the type of data to be retransmitted is voice data. If the data is voice data, the retransmission number calculation uses a maximum number of retransmissions that is smaller than the maximum number of retransmissions in the case of other than voice data. With steps and
The retransmission control step ends the retransmission of the data when the number of retransmissions of the data reaches the maximum number of retransmissions. A wireless interface unit that performs wireless communication by individually connecting to a plurality of wireless terminals, and relays and transfers data received from a host device to the wireless terminal by the wireless communication and receives from the wireless terminal by the wireless communication A wireless communication control method used in a wireless access point including a relay transfer processing unit that relays and transfers the received data to the host device,
When the retransmission control unit cannot receive an acknowledgment from the wireless terminal for the data transmitted to the wireless terminal, a retransmission control step for performing retransmission of the data;
The retransmission number calculation unit counts the number of wireless terminals connected to itself by the wireless communication among the wireless terminals, and the maximum number of retransmissions after the maximum number of retransmissions monotonously decreases in accordance with the increase in the number of connected terminals. A retransmission number calculating step for calculating a maximum number of retransmissions corresponding to the number of connected terminals based on the relationship between the number of connected terminals and the maximum number of retransmissions,
The retransmission control step ends the retransmission of the data when the number of retransmissions of the data reaches the maximum number of retransmissions.

Images