JP2003348104A - Wireless access point - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize a transmission amount of the beacon frames in a wireless access point. <P>SOLUTION: The wireless access point refers to a database to discriminate whether or not a wireless station terminal STA in an association state exists, and stops supply of power to a wireless transmission section 102, that is, stops transmission of the beacon frames when no wireless station terminal STA is in the association state at all. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a wireless access point in a wireless LAN system.

[0002]

2. Description of the Related Art In an IEEE 802.11 system,
It is possible to construct a wireless LAN system using a wireless access point and a wireless station terminal in an infrastructure mode. The wireless station terminal
Notebook P having a network interface processing unit such as a wireless LAN adapter having a wireless signal transmission / reception function
C and other data terminals. The wireless access point has an interface function between a wireless communication network and a wired network, a function of transmitting and receiving a wireless signal, a function of controlling a wireless signal (by firmware), and a MAC address authentication function.

When a wireless station terminal communicates with a wireless access point, a physical range within which a wireless signal from the wireless access point reaches (hereinafter referred to as a wireless area).
Must be located within. On the other hand, the wireless access point periodically transmits a system information signal called a beacon frame, and the wireless station terminal can know the existence of the wireless access point by receiving the beacon frame. Can communicate with points. Thereby, power saving by intermittent operation is possible.

[0004] When a wireless station terminal and a wireless access point communicate with each other, mutual authentication between the two is required. An open authentication process defined in the IEEE 802.11 standard is performed, and an association is established.
on) state. The wireless access point writes the information of the wireless station terminal in the association state into the internal database, and uses the information at the time of polling after transmitting the beacon frame. At this point, the wireless access point can perform polling and data transmission to the wireless station terminal.

[0005]

However, according to the above-mentioned prior art, the wireless access point keeps transmitting a periodic beacon frame even when there is no wireless station terminal in the wireless area. There is a possibility that other systems using the band may be adversely affected, and power is consumed by unnecessary radio wave transmission.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to minimize beacon frame transmission.

[0007]

According to the present invention, there is provided a wireless access point of a wireless LAN system for transmitting a system information signal to a wireless station terminal in a wireless area. Since there is a control means for stopping the system information signal when it does not exist, transmission of a beacon frame can be minimized.

[0008] The wireless access point according to the present invention, in a state where communication with the wireless station terminal is not performed,
A signal may be transmitted to the wireless station terminal asking whether or not to stop the system information signal, and when there is no response thereto, the control means may stop transmitting the system information signal.

The wireless access point according to the present invention further comprises storage means for storing a database for registering information on wireless station terminals with which communication is possible, and when there is no wireless station terminal to communicate in the wireless area. Alternatively, all the information of the wireless station terminal may be deleted from the database, and at this time, the control means may stop transmitting the system information signal.

[0010] A wireless access point according to the present invention restarts transmission of a system information signal by a control means when a wireless station terminal transmits a signal requesting communication while a system information signal is stopped. It may be.

In the wireless access point according to the present invention, the control means may stop transmitting the system information signal when there is no response from the wireless station terminal to the polling signal.

In the wireless access point according to the present invention, the storage means registers the time of last communication with the wireless station terminal together with information of the wireless station terminal in a database, and the control means wirelessly stores the information for a predetermined time from the last communication time. When the communication with the station terminal is not performed, the information of the wireless station terminal may be deleted from the database, and the control unit may stop transmitting the system information signal.

In the wireless access point according to the present invention, the system information signal may be a beacon frame.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a wireless access point according to the present invention will be described with reference to the drawings. [First Embodiment] FIG. 1 is a block diagram showing a first embodiment of a wireless access point according to the present invention, and FIG.
FIG. 2 is a block diagram illustrating a wireless area and a wireless station terminal according to the first embodiment.

In FIG. 1, a wireless access point 10
Reference numeral 1 denotes an antenna 110 and a radio transmission unit 10 connected to the antenna 110 and transmitting a transmission radio signal from the antenna 110 by performing packet assembly, communication control, modulation, and the like.
And a radio receiving unit connected to the antenna 110 and performing error correction encoder / decoder, packet disassembly, communication control, frame error check, bit synchronization circuit, demodulation, etc. on the received signal received by the antenna 110 103.

The wireless access point 101 is provided with a network interface processing unit 105 and can be connected to a data terminal (not shown) such as a notebook PC.

The wireless access point 101 further includes a control unit 108 for controlling the beacon frame transmission stop and other functions in the wireless access point 101, a storage unit 104 for storing a database and other data, and a polling unit for polling wireless station terminals. A timer unit 107 that measures a standby time when a signal is transmitted, a determination unit 109 that determines whether or not to stop transmitting a beacon frame,
And a comparison unit 106 that performs a comparison operation for the determination in the determination unit 109.

FIG. 2 shows a wireless area in which only two wireless station terminals STA (202, 203) are present for the sake of simplicity.
A (202, 203) is a wireless access point AP (2
01).

The wireless access point AP (201) periodically transmits a beacon frame, and the wireless station terminals STA (202, 203) receive the beacon frame, thereby receiving the beacon frame.
Know the presence of 1) and communicate with the wireless access point at any time. Thereby, power saving by intermittent operation is possible.

The wireless station terminal STA and the wireless access point AP perform open authentication processing according to the IEEE 802.11 standard, and enter an association state. The wireless access point AP writes information of the wireless station terminal STA in the association state into the database 601 (FIG. 6) in the storage unit 104.

FIG. 3 is a sequence diagram showing a communication procedure between the wireless access point AP and the wireless station terminal STA. In the first embodiment, when there is no associated wireless station terminal in the wireless area, transmission of the beacon frame is stopped. In a state where the wireless access point AP has stopped transmitting the beacon frame, when the wireless station terminal STA performs communication, it sends out a probe request (501) to the wireless access point AP. In response to this, the wireless access point AP sends out a probe response (502), so that the wireless access point AP and the wireless station terminal STA enter a communication establishment phase (5).
03), the communication phase is reached (504).

As described above, since the transmission of the beacon frame is stopped when there is no wireless station terminal STA to communicate with, the influence on the equipment having the same frequency as that of the wireless access point AP can be minimized. The point AP can save power.

FIG. 4 is a flowchart showing the processing of the wireless access point AP. Step S401: The wireless access point AP refers to the database 601 by the control unit 108, and determines whether or not the wireless station terminal STA in the association state exists. If there is a wireless station terminal STA in the association state, step S
While repeating 401, a beacon frame is periodically transmitted. If there is no wireless station terminal STA in the association state, step S4
Move to 02. Step S402: When there is no wireless station terminal STA in the association state, power supply to the wireless transmission unit 102 is stopped. That is, transmission of the beacon frame is stopped. Step S403: When communication with the wireless access point AP is required in the wireless area 204, the wireless station terminal STA sends a probe request to the wireless access point AP. At this time, the wireless access point monitors whether a probe request has been received. If not received, step S403 is repeated, and if received, the process proceeds to step S404. Step S404: When receiving the probe request, the wireless access point AP starts supplying power to the wireless transmission unit 102 and restarts transmitting a beacon frame. Step S405: The wireless access point AP sends out a probe response to the wireless station terminal STA that sent out the probe request, and step S40
Move to 6. Step S406: The wireless access point AP refers to the contents of the probe request received in step S403, writes the MAC address of the wireless station terminal STA that sent the probe request into the database 601, and proceeds to step S407. Step S407: The wireless station terminal STA having received the probe response and the wireless access point A
P indicates a communication establishment phase, and the process proceeds to step S408. Step S408: The wireless station terminal STA having received the probe response and the wireless access point A
P indicates a communication phase, and the process proceeds to step S409. Step S409: It is determined whether a disassociation notification has been received from the wireless station terminal STA. The notification of the disassociation is transmitted to the wireless access point AP when the wireless station terminal STA enters a communication disabled state such as turning off the power.
If it has been received, the process proceeds to step S412 described below, and if it has not been received, the process proceeds to step S410. Step S410: It is determined whether or not there is a wireless station terminal STA with which communication is not performed even though the MAC address is described in the database 601. If it does not exist, the process returns to step S408, and if it exists, the process proceeds to step S411. Step S411: When communication becomes impossible, for example, when the wireless station terminal STA goes out of the wireless area, the database 60 is transmitted without notification of disassociation.
1 to delete the data of the wireless station terminal STA. Therefore, the wireless station terminal STA
It is determined whether or not the wireless station terminal STA whose MAC address is described in the database 601 has not been in communication for a predetermined time or more, and when it has reached the predetermined time, it is estimated that it is in a communication disabled state. If the predetermined time has elapsed, the flow shifts to step S412. If the predetermined time has not elapsed, the flow returns to step S408. Step S412: The MAC address is deleted from the database 601 for the wireless station terminal that has received the disassociation notification or the communication suspension time has expired, and returns to step S401. *

FIG. 5 is a flowchart showing the processing of the wireless station terminal STA. Step S501: The wireless station terminal STA determines whether or not to perform communication. If communication is unnecessary, the wireless station terminal STA holds a disassociation state of step S509 described later, and if communication is to be performed, the process proceeds to step S502. Step S502: The time from when it is determined that communication should be performed is measured by the timer unit 107. Step S503: A probe request is sent, and the routine goes to Step S504. Step S504: It is determined whether or not the probe response transmitted by the wireless access point AP that has received the probe request has been received. If the probe response has been received, the process proceeds to step S506 described below.
Move to 505. Step S505: It is determined whether or not the time after determining that communication should be performed has reached a predetermined value. If the time has not reached the predetermined time, the process returns to step S503 and sends out the probe request again. When the probe response cannot be received within a predetermined time, such as when the wireless access point AP does not exist, or when the communication environment is poor due to interference with other devices,
It returns to step S501. Step S506: Move to the communication establishment phase. Step S507: Move to the communication phase. At this time, in the case of the disassociation state, the state shifts to the association state. Step S508: Whether the wireless station terminal STA moves outside the wireless area 204, cannot receive a beacon frame from the wireless access point AP, or performs an operation of turning off the power of the wireless station STA. Determine whether or not. When the association state is to be maintained, the process returns to step S507, and when the communication is to be ended, the process proceeds to step S509. Step S509: When communication with the wireless access point AP becomes impossible, the wireless access point AP is notified of transition to the disassociation state. As described above, when the wireless access point AP is notified of the disassociation state from the wireless station terminal STA, the wireless access point AP deletes the MAC address of the wireless station terminal STA that has notified the disassociation state from the database 601. If no wireless station terminal STA in the association state is registered in the database 601, the power supply to the wireless transmission unit 102 is stopped. In addition, the wireless station terminal STA has moved out of the wireless area of the wireless access point AP, and the like.
If communication is not possible with the wireless station terminal STA
Goes into disassociation state.

FIG. 6 is a table showing a database 601 stored in the storage unit 104.

The database 601 includes a radio station terminal STA (202, 2
03), its unique MAC address is stored. A field filled with "FF" means that there is no data. The wireless station terminal STA (20
(2, 203), the communication is terminated, and the MAC address is deleted from the database 601. Therefore, the wireless access point AP can refer to the wireless station terminal STA in the association state by the database 601. [Second Embodiment] FIGS. 7 and 8 are sequence diagrams showing a communication procedure with a wireless station terminal according to a second embodiment. Configuration of the wireless access point of the second embodiment,
The situation of the wireless station terminal in the wireless area is the same as in the first embodiment, and a description thereof will be omitted. The same or corresponding parts as in the first embodiment are denoted by the same reference numerals.

In FIG. 7, the database 601 stores MA
When no communication is performed with the wireless station terminal in which the C address is registered (association state), the wireless access point AP transmits a CF polling frame (701 to 703 in FIG. 7 and 801 to 80 in FIG. 8).
3). FIG. 7 shows a case in which one of the wireless station terminals transmits an ACK frame (70).
4), FIG. 8 shows a case where there is no wireless station terminal transmitting an ACK frame. When the wireless access point AP receives the ACK frame, the wireless access point AP continues transmitting a beacon frame. In addition, since the communication environment may be bad, the CF polling frame may be transmitted a plurality of times.

The sequence in a state in which the wireless access point AP has stopped transmitting a beacon frame is the same as in the first embodiment, and includes a probe request (804 in FIG. 8),
Processing proceeds in the order of a probe response (805 in FIG. 8), a communication establishment phase (806 in FIG. 8), and a communication phase (807 in FIG. 8).

In the second embodiment, in addition to the effect of the first embodiment, since the wireless station terminal in the wireless area is always monitored and the beacon frame is maintained, the communication can be smoothly restarted.

FIG. 9 is a flowchart showing processing of the wireless access point according to the second embodiment. Step S901: The wireless access point AP periodically transmits a CF polling frame to the wireless station terminal STA whose MAC address is registered in the database 601, and proceeds to step S902. Step S902: The timer 107 starts measuring the standby time for receiving the ACK frame, and then proceeds to step S9.
Shift to 03. Step S903: It is determined whether or not an ACK frame has been received from the wireless station terminal. If it has been received, the process returns to step S901; otherwise, the process proceeds to step S904. Step S904: It is determined whether or not the waiting time for receiving the ACK frame has expired. If it has expired, the process moves to step S905. If it has not expired, the process returns to step S903. Step S <b> 905: The MAC address of the wireless station terminal that has not responded despite transmitting the CF polling frame is deleted from the database 601. Step S906: Referring to the database 601, it is determined whether or not data of the wireless station terminal remains. When there is no data, the process proceeds to step S907, and when data remains, the process returns to step S901. Step S907: The power supply to the wireless transmission unit 102 is stopped, and the transmission of the beacon frame is stopped. Step S9
As shown in steps 07 to S910, the subsequent communication restart processing is the same as in the first embodiment. Step S908: It is determined whether a probe request has been received. If not received, step S908
Are repeated, and when it is received, the process proceeds to step S909. Step S909: Power supply of the wireless transmission unit 102 and transmission of the beacon frame are restarted. Step S910: Send a probe response to the wireless station terminal STA that sent the probe request. Step S911: The MAC address of the wireless station terminal STA is written in the database 601, and the process moves to step S912. Step S912: The communication establishment phase is established, and the process proceeds to step S913. Step S913: It becomes a communication phase, and step S9
Return to 01.

FIG. 10 is a flowchart showing the processing of the wireless station terminal communicating with the second embodiment.
In the wireless station terminal according to the second embodiment, the processes from the communication request to the transition to the communication phase are the same as steps S501 to S507 in the first embodiment. However, it is determined whether communication is necessary (step S50 in the first embodiment).
When the communication becomes unnecessary in 1), it is determined whether or not the CF polling frame has been received without repeating the determination of the necessity of the communication, and an ACK frame is transmitted when the CF polling frame is received. Step S1001: It is determined whether or not communication is necessary. If communication is not required, the process proceeds to step S1010, which will be described later. Step S1002: Time is measured after it is determined that communication should be performed. Step S1003: Send a probe request. Step S1004: It is determined whether or not a probe response has been received. If it has been received, the process proceeds to step S1006, and if not, the process proceeds to step S1005. Step S1005: If the time since it is determined that communication should be performed has not reached the predetermined time, the flow returns to step S1003, and if the time has expired, the flow shifts to step S1001. Step S1006: Move to the communication establishment phase. Step S1007: Move to the communication phase. As in the first embodiment, when the terminal is not in the association state, the terminal enters the association state. Step S1008: Step S50 of the first embodiment
Similarly to 8, it is determined whether or not the communication should be terminated. If the association state should be maintained, step S100
7 and when the communication should be terminated, step S100
Move to 9. Step S1009: Measurement of the time after determining that the communication should be ended is started, and the process proceeds to step S1010. Step S1010: It is determined whether or not a CF polling frame has been received.
Move to If not received, step S described later
The process proceeds to 1012. Step S1011: Transmit an ACK frame, and proceed to step S1012. Step S1012: It is determined whether or not the time from the communication end determination has reached a predetermined value. Step S when time expires
The flow shifts to 1013, and if not expired, returns to step S1010. Step S1013: It becomes a disassociation state, and returns to step S1001. [Third Embodiment] FIGS. 11 and 12 are sequence diagrams showing a communication procedure with a wireless station terminal according to a third embodiment. The configuration of the wireless access point according to the third embodiment, the status of the wireless station terminal in the wireless area is the first.
The description is omitted because it is the same as that of the first embodiment. The first
The same reference numerals are given to the same or corresponding parts as those of the embodiment.

The third embodiment employs a random access method as a communication method between the wireless station terminal STA and the wireless access point AP. At the time of random access, the wireless station terminal STA sends a data frame to the wireless access point AP (1101 in FIG. 11 and 1201 in FIG. 12).

The confirmation of the necessity of transmitting the beacon frame is performed by transmitting a beacon frame stop confirmation message to the wireless station terminal STA when the time from when the last data frame is received reaches a predetermined value. FIG.
Means that any of the wireless station terminals
FIG. 1 shows a case where a CK frame is transmitted (1103).
No. 2 is a case where there is no wireless station terminal transmitting the ACK frame. Wireless station terminal S
When the TA transmits an ACK frame to the wireless access point AP, the wireless access point AP continues to transmit a beacon frame.

The third embodiment can minimize power consumption in the random access system.

FIG. 13 is a flowchart showing the processing of the wireless access point according to the third embodiment. Step S1301: It is determined whether or not a data frame has been received from the wireless station terminal STA. If the data frame has been received, the process proceeds to step S1302, and if not, the process proceeds to step S1303. Step S1302: The time at which the last data frame was received from each wireless station terminal is stored in the database 150.
1 and the process moves to step S1303. Step S1303: The time of the database 1501 and the current time are compared by the comparing unit 106, and it is determined whether or not the communication suspension waiting time has expired. If it has expired, the flow shifts to step S1304. If it has not expired, the flow returns to step S1301. Step S1304: When the standby time for communication interruption has expired, a beacon frame stop confirmation message is transmitted to all the wireless station terminals STA whose MAC addresses are registered in the database 1501. Step S1305: Start time measurement after transmitting the beacon frame stop confirmation message, and step S1
Move to 306. Step S1306: AC from wireless station terminal
It is determined whether or not a K frame has been received. If the K frame has been received, the process returns to step S1301, and if not, the process proceeds to step S1307. Step S1307: It is determined whether or not the waiting time after transmitting the beacon frame stop confirmation message has expired. If it has expired, the process moves to step S1308, and if it has not expired, the process returns to step S1306. Step S1308: Delete the MAC addresses of all wireless station terminals from the database 1501, and proceed to step S1309. Step S1309: The power supply to the wireless transmission unit 102 is stopped, and the transmission of the beacon frame is stopped. Step S13
As shown in steps S10 to S1315, the subsequent communication restart processing is the same as steps S403 to S408 in the first embodiment. Step S1310: It is determined whether a probe request has been received. If not received, step S13
10 is repeated, and when it is received, the process proceeds to step S1311. Step S1311: restart the power supply of the wireless transmission unit 102 and the transmission of the beacon frame. Step S1312: Send a probe response to the wireless station terminal STA. Step S1313: Write the MAC address of the wireless station terminal STA into the database 1501, and proceed to step S1314. Step S1314: It becomes the communication establishment phase, and shifts to step S1315. Step S1315: It becomes the communication phase, and step S
It returns to 1301.

FIG. 14 is a flowchart showing the processing of the wireless station terminal communicating with the third embodiment. Step S1401: It is determined whether communication is necessary. If communication is necessary, the process proceeds to step S1402. If communication is not required, step S1401 described later is repeated. Step S1402: The data frame is transmitted, and the procedure goes to step S1403. Step S1403: It is determined whether or not the communication is completed. If the communication is completed, the process returns to the step S1401.
Move to 404. Step S1404: It is determined whether or not a beacon frame stop message has been received.
The process proceeds to 1405, and if not received, step S1402
Return to Step S1405: Send an ACK frame to the wireless access point AP.

FIG. 15 is a table showing a database 1501 in the third embodiment. In the third embodiment, since it is necessary to manage the communication interruption time at the time of random access, the last data frame reception time is registered for each wireless station terminal. When the MAC address is deleted in the disassociation state, the data frame reception time is also deleted.

[0038]

As described above, according to the present invention, the transmission of beacon frames by wireless access points can be minimized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a wireless access point according to the present invention.

FIG. 2 is a block diagram illustrating a wireless area and a wireless station terminal according to the first embodiment.

FIG. 3 is a sequence diagram illustrating a communication procedure with the wireless station terminal according to the first embodiment.

FIG. 4 is a flowchart illustrating processing of a wireless access point according to the first embodiment.

FIG. 5 is a flowchart illustrating processing of a wireless station terminal communicating with the first embodiment.

FIG. 6 is a table showing a database in the first embodiment.

FIG. 7 is a first sequence diagram illustrating a communication procedure with a wireless station terminal according to the second embodiment.

FIG. 8 is a second sequence diagram illustrating a communication procedure with the wireless station terminal according to the second embodiment.

FIG. 9 is a flowchart illustrating processing of a wireless access point according to the second embodiment.

FIG. 10 is a flowchart illustrating a process of a wireless station terminal communicating with the second embodiment.

FIG. 11 is a first sequence diagram illustrating a communication procedure with a wireless station terminal according to the third embodiment.

FIG. 12 is a second sequence diagram illustrating a communication procedure with the wireless station terminal according to the third embodiment.

FIG. 13 is a flowchart illustrating processing of a wireless access point according to the third embodiment.

FIG. 14 is a flowchart showing processing of a wireless station terminal communicating with the third embodiment.

FIG. 15 is a table showing a database in the third embodiment.

[Explanation of symbols]

101 access point 601, 1501 database AP, 101, 202 Wireless access point STA, 202, 203 Wireless station terminal

Claims (7)

[Claims] 1. A wireless access point of a wireless LAN system for transmitting a system information signal to a wireless station terminal in a wireless area, wherein when there is no wireless station terminal to communicate in said wireless area, said system A wireless access point comprising control means for stopping an information signal. 2. In a state where communication with the wireless station terminal is not performed, the wireless station terminal
2. The wireless access point according to claim 1, wherein a signal for inquiring whether or not to stop the system information signal is transmitted, and when there is no response thereto, the control unit stops transmitting the system information signal. 3. A storage unit for storing a database for registering information on wireless station terminals having a possibility of communication, wherein when there is no wireless station terminal to be communicated in the wireless area, wireless communication is performed from the database. 3. The wireless access point according to claim 1, wherein all information of the station terminal is deleted, and at this time, the control unit stops transmitting the system information signal. 4. When the wireless station terminal transmits a signal requesting communication while the system information signal is stopped, the control means restarts transmission of the system information signal. The wireless access point according to claim 1. 5. The wireless communication system according to claim 1, wherein the control unit stops transmitting the system information signal when there is no response to the polling signal from the wireless station terminal. 2. The wireless access point according to claim 1. 6. The storage means registers the time of last communication with the wireless station terminal together with the information of the wireless station terminal in the database, and the control means stores the time with the wireless station terminal for a predetermined time from the last communication time. 5. The wireless access point according to claim 3, wherein when communication is not performed, information on the wireless station terminal is deleted from the database, and the control unit stops transmitting the system information signal. 7. The wireless access point according to claim 1, wherein the system information signal is a beacon frame.