JP2004165953A - Radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently utilize a radio medium and to improve a power saving effect in a radio communication system. <P>SOLUTION: The radio communication system is constituted of: a base station having a plurality of APs connecting cable communication and radio communication and managing a plurality of radio terminals; and the plurality of radio terminals. The base station has channels and ESS-IDs connected with the radio terminals for the same number as the plurality of APs, and the plurality of APs manage connections with the radio terminals by using respectively different channels and ESS-IDs. The base station specifies the plurality of APs with the smallest number of the connections when the number of the connected radio terminals becomes a predetermined number or less. The base station checks whether the plurality of APs and the connected terminals are transmitting/receiving of data, and when they are not, stops the supply of power to the specified APs or switches to a low power consumption mode. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is directed to a wireless communication system including a plurality of base stations and a plurality of wireless terminals each having a plurality of access points for connecting a wired communication and a wireless communication and managing a plurality of wireless terminals. The present invention relates to a method of controlling terminal connection for each point function.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been a wireless LAN system that configures a network between a bridge device connected to a wired LAN and a large number of wireless terminals.
[0003]
The wireless LAN system includes an access point (hereinafter, AP) serving as a bridge with the wired LAN system, and one or more wireless terminals (hereinafter, STAs) communicating with the AP.
[0004]
The AP sends out a broadcast signal (beacon signal) at a constant cycle. When the STA is powered on, the STA starts searching for a beacon signal from the AP. The search method includes a method of searching for an AP transmitting a beacon signal with a channel and an AP identification code registered in advance in the STA, a method of transmitting a probe signal (AP search signal) from the STA and receiving a probe response from the operating AP, and the like. There is.
[0005]
The STA that has detected the connection destination AP transmits a management frame and performs negotiation processing such as authentication confirmation and connection processing for the AP.
[0006]
After the negotiation process, each STA connected to the AP can establish synchronization by receiving a beacon signal, join a wireless LAN system, and perform data communication.
[0007]
The data communication method is a “centralized control method” in which the AP polls each terminal and controls the transmission of the terminal during a “Contention Free” period from when the AP transmits the beacon signal to when the AP transmits the Content Free-End (CF-End). And a distributed control method in which the RTS-CTS method is used to confirm the occupation of the wireless medium to another terminal and inform the other terminal of the occupation period.
[0008]
[Problems to be solved by the invention]
For example, a wireless LAN system based on the IEEE 802.11b system can use 14 channels. However, in assuring the transmission speed in the adjacent space, even if there are 14 channels, only 4 channels among them can be actually used without interference.
[0009]
Therefore, for example, in the case of a device that accommodates four APs in the same housing as shown in FIG. 1, one device occupies all available channels without interference as shown in FIG. Therefore, other APs existing in the same cell cannot operate because they cannot find an available channel.
[0010]
Also, for example, in the configuration shown in FIG. 1, the maximum number of STAs (109) in the APs (105 to 108) is set to, for example, three in order to guarantee the transmission speed. As shown in the figure, the number of operating STAs is six, so two APs are normally sufficient. This occupies two extra channels and consumes extra power for two APs.
[0011]
[Means for Solving the Problems]
According to the present invention, in a wireless communication system configured by a plurality of wireless terminals and a base station having a plurality of access point functions for connecting a wired communication and a wireless communication and managing a plurality of wireless terminals,
The base station has the same number of channels and access point identification codes as the plurality of access point functions, and
Means for managing the connection with the wireless terminal with the plurality of access point functions are respectively different channel and access point identification code,
The base station, when the number of connected wireless terminals is equal to or less than a predetermined number, means for identifying the plurality of access point functions with the least number of connected,
Means for checking whether the plurality of access point functions and their connected terminals are transmitting and receiving data,
If the specified access point function is not performing data communication, the power supply to the specified access point function is provided with means for stopping power supply or switching to low power supply,
Means for storing the plurality of channels and the plurality of access point identification codes,
Means for setting a priority for connection to the access point identification code,
A means for searching for an access point function that operates with the access point identification code having a higher priority than the plurality of access point functions, and performing a connection process,
The wireless terminal operates with the access point identification code having the next higher priority than the plurality of access point functions when the broadcast signal transmitted by the access point function in the connected state cannot be received. By providing means for searching for an access point function to be performed and performing a connection process, it is possible to obtain an efficient use of a wireless medium and an effect of power saving.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
(Example 1)
FIG. 1 shows a configuration example of the present invention.
[0013]
FIG. 1 is a configuration diagram of a wireless communication system in which a plurality of STAs (109) are managed by a base station (101, hereinafter referred to as MFAP) that accommodates four APs (105 to 108) in the same housing.
[0014]
The MFAP (101) performs connection processing with the wireless terminal (109, hereinafter referred to as STA) using different channels and different AP identification codes (hereinafter referred to as ESS-ID) via the APs (105 to 108), and is connected to the wired LAN.
[0015]
The AP operation state monitoring unit (102) includes information on the AP acquired by the AP management unit (104) and the connection STA (109) for the MFAP control unit (103) to monitor the operation state of each AP (105 to 108). The information about is stored. As an example of the acquired information, it is managed by a table as shown in FIG. 3, for example. The contents include the name of each AP, the AP priority (Priority) indicating the operation priority of the APs (105 to 108), the STA name (User Name) to which each AP (105 to 108) is currently connected, and each STA (109). MAC address, ESS-ID (ESS-ID) used by APs (105-108), channel (CH) used by APs (105-108), and AP ( 105-108), the packet content (AP → User) last transmitted to the connection terminal, the packet content (User → AP) last transmitted from the connection terminal to the AP (105-108), and the like.
[0016]
The MFAP control unit (103) issues an instruction to update the AP operation state information table (FIG. 3) of the AP operation state monitoring unit (102) to the AP management unit (104). Further, based on the contents of the AP operation state information table (FIG. 3), the control unit (104) issues an instruction such as operation control of the AP to the AP management unit (104).
[0017]
The AP management unit (104, hereinafter referred to as APM) receives a control instruction regarding the AP (109) from the MFAP control unit (103), acquires communication information and transmission / reception packet information from the AP according to SNMP, and monitors the AP operation state. The update processing of the AP operation state information table (FIG. 3) of the unit (102), power supply control, and the like are executed.
FIG. 4 shows the configuration of the APs (105 to 108).
[0018]
The MFAP I / F processing unit (401) is an interface unit that processes transmission and reception of data with the MFAP (101).
[0019]
The AP control unit (402) analyzes, for example, a data packet conforming to the IEEE802.11b standard, is further equipped with firmware such as wireless signal control and a MAC address authentication function, and has an interface function with a wired network.
[0020]
The data processing unit (403) converts information to be transmitted by the AP control unit (402) into a predetermined transmission data format, or extracts received information to be passed to the AP control unit (402) from received data.
[0021]
A modulation / demodulation unit (404) modulates transmission data to generate a transmission signal, and demodulates a reception signal to extract reception data.
[0022]
A wireless transmission / reception processing unit (405) converts a transmission signal to a predetermined frequency, performs processing such as amplification and filtering, generates a wireless transmission signal, or converts a wireless reception signal to a predetermined frequency, and performs amplification and filtering. Processing is performed to generate a received signal.
[0023]
The antenna (407) transmits the generated radio transmission signal to the radio transmission / reception processing unit (405) and receives the radio signal. Here, the APs (105 to 108) limit the maximum number of STAs to be connected in order to secure the transmission speed, and allow only up to three STAs.
[0024]
The STA (109) is a plurality of terminal stations, the configuration of which is shown in FIG.
[0025]
The PC card (503) is, for example, a PC card type wireless LAN adapter having a wireless signal transmission / reception function conforming to the IEEE 802.11b standard.
[0026]
The notebook PC (502) is equipped with the PC card type wireless LAN adapter (503) and starts the installed STA driver software, so that the user can use the input screen (501) to enter the ad-hoc mode or the infrastructure mode. It enables setting of communication parameters such as setting, communication channel, and ESS-ID.
[0027]
Here, in each STA, ST1 and ST2 are in AP1 (ESS-ID = Group1), ST3, ST4, and ST5 are in AP2 (ESS-ID = Group2), ST6 is in AP3 (ESS-ID = Group3), and ST7 is The ESS-ID is set in advance so as to be preferentially connected to the AP 4 (ESS-ID = Group 4). In addition, in preparation for the case where the priority connection destination AP cannot be detected, AP1 is set as the second connection destination in ST1 and ST2, AP3 is set as the second connection destination in ST3, ST4, and ST5, and AP4 is set as the second connection destination in ST6. In step ST7, AP1 is registered as the second connection destination. Similarly, the third and fourth connection destination APs are also registered. The display of the notebook PC (502) in FIG. 5 shows the setting contents of ST7.
[0028]
(110) is a wired network such as an Ethernet cable, and (111) is a power supply unit that supplies power obtained from AC or the like to each block.
[0029]
Next, a specific operation will be described with reference to an ARM operation flowchart in FIG. 7, a sequence diagram in FIG. 9, and a system configuration diagram in FIG. 10 as an example of an operation according to a communication protocol conforming to IEEE 802.11b as a wireless communication unit. explain.
[0030]
First, in FIG. 10, the power is turned on to the MFAP (101) to start the operation. Each AP (105 to 108) starts transmitting a beacon signal on a different channel and ESS-ID (901). Each AP (105 to 108) notifies the APM (104) that the transmission of the beacon signal has been completed (902, S701). Further, when each of the APs (105 to 108) has completed transmitting the Contention Free-End signal (hereinafter, CF-End signal) (903), the AP (104) notifies the ARM (104) of the end of the Contention Free period by "CFP end notification" ( 904, S702).
[0031]
Upon receiving the “CFP end notification” from AP1, the APM (104) transmits an “AP1 data acquisition request” to AP1 (905, S703). Upon receiving the "AP1 data acquisition request", AP1 grasps the name of the connected STA, the MAC address of the connected STA, the ESS-ID used by AP1, the channel used by AP1, and the communication status of AP1. To do so, the AP1 (104) responds to the APM (104) by setting the contents of the packet last transmitted from the AP1 to the connection terminal and the contents of the packet last transmitted from the connection terminal to the AP1 to "AP1 data acquisition response" (906).
[0032]
Upon receiving the "AP1 data acquisition response" (S704), the ARM (104) accesses the AP operation state monitoring unit (102) and updates the AP operation state information table (FIG. 3) (S705). After the update is completed, the ARM (104) transmits an “AP1 data acquisition completion notification” to the MFAP control unit (103) (907, S706). The MFAP control unit (103) that has received the “AP1 data acquisition completion notification” accesses the AP operation state monitoring unit (102), and acquires the AP operation state information by reading the AP operation state information table (FIG. 3). The same processing is performed for AP2 (not shown), AP3 (not shown), and AP4 (908 to 912), and the MFAP control unit (103) acquires the latest AP operation state information for all APs. Can be.
[0033]
The AP and the STA confirm that the AP and the STA are in operation, for example, by receiving the beacon signal from each AP by the STA or by transmitting the probe response from the AP receiving the probe signal from each STA. Each STA performs an authentication check and a connection sequence with the AP, shifts to a state where data communication is possible, and according to the parameters previously set for each STA, as shown in FIG. One STA is connected to each of AP3 and AP4.
[0034]
How the MFAP control unit (103) controls the operation of the AP based on the AP operation state information table (FIG. 3) will be described using AP4 and ST7.
[0035]
FIG. 6 shows an operation flowchart of the MFAP control unit (103). When the ST 7 and the AP 4 perform an authentication check and a connection sequence (913), and shift to a state in which data communication is possible, the APM (104) performs the same procedure as described above in accordance with the flowchart of FIG. And updates the AP operation state information table (FIG. 3) and transmits an “AP4 data acquisition completion notification” to the MFAP control unit (103) (916 to 920).
[0036]
Upon receiving the "AP4 data acquisition completion notification" (S601), the MFAP control unit (103) accesses the AP operation state monitoring unit (102) and, based on the AP operation state information table (FIG. 3), determines the number of active APs (hereinafter Na, initial The value is Na = 4), and the total number of STAs connected to the base station (101) (hereinafter Ns, since the maximum number of connections of one AP is 3, the maximum value Na × 3 = 12) is acquired (S602, S603).
[0037]
Next, “Ns” and “(Na−1) × 3” are compared to determine whether or not the connected STA can be managed even when one AP is stopped (“3” is the maximum number of STAs connected to the AP. S604) ).
[0038]
When the “Ns” value is smaller than the “(Na−1) × 3” value, the MFAP control unit (103) determines that the management of all STAs is possible even when the operation of one AP is stopped while the base station (101) is connected. it can. When the value of “Ns” is larger than the value of “(Na−1) × 3”, the MFAP control unit (103) stops the operation of one AP, so that all STAs cannot be managed while the base station (101) is connected. The process ends.
[0039]
If it is determined that the “Ns” value is smaller than the “(Na−1) × 3” value, a search is made for “the AP with the smallest number of connected STAs” (S605). In the case of the configuration diagram in FIG. 10, AP3 and AP4 correspond. When there are a plurality of corresponding APs as shown in FIG. 10 (S606), the lower one of the AP priorities (Priority) in the AP operation state information table of FIG. 3 is selected (S607). In the case of the configuration diagram in FIG. 6, AP4 is selected from the AP operation state information table (FIG. 3).
[0040]
Next, the MFAP control unit (103) uses “AP4 last transmitted packet to ST7” and “ST7 last transmitted packet to AP4” in order to grasp the communication status of AP4 from the AP operation state information table (FIG. 3). The packet content is acquired (S608).
[0041]
In FIG. 9, “the last packet content transmitted from AP4 to ST7” and “the last packet content transmitted from ST7 to AP4” are “Data + CF-Poll” (914) and “Data− + Ack” (915), respectively. . That is, in AP4 and ST7, the "data and polling" signal and the "data and acknowledgment" signal are the latest transmission / reception histories, and it is understood that AP4 and ST7 are performing data communication (S609). Since data communication is being performed with AP4 and ST7, the MFAP control unit (103) ends the process.
[0042]
After a certain period of time, the APM (104) receives the beacon transmission completion notification (922) from the AP4 again, acquires the operation state information of the AP4 in the same procedure, updates the AP operation state information table (FIG. 3), and updates the MFAP. A "AP4 data acquisition completion notification" is transmitted to the control unit (103) (926 to 929).
[0043]
The MFAP control unit (103) starts the process again according to the flowchart of FIG. 6, and if the communication status is confirmed again in (S608), "the contents of the last packet transmitted from AP4 to ST7" The last transmitted packet content is “CF-Ack + CF-Poll” (923) and “CF-Ack” (924), respectively. That is, in AP4 and ST7, the "acknowledgement and polling" signal and the "acknowledgement" signal are the latest transmission / reception histories, and it can be seen that data communication has been completed between AP4 and ST7 (S609).
[0044]
The MFAP control unit (103), which has confirmed that the AP 4 has terminated the data communication, transmits an “AP power supply stop request” (930) of the AP 4 to the APM (104) (S610).
[0045]
FIG. 8 shows a flowchart when the APM (104) receives an "AP power supply stop request" from the MFAP control unit (103).
[0046]
Upon receiving the “AP power supply stop request” from the MFAP control unit (103), the APM (104) notifies the AP 4 of an “authentication release transmission request” (931, S801). The AP 4 that has received the “authentication release transmission request” transmits an “authentication release notification” to the connected STA (932), and transmits an “authentication release transmission request response” to the APM (104) (933).
[0047]
Upon receiving the “authentication release transmission request response” (S802), the APM (104) stops power supply to the AP 4 (S803) and updates the AP operation state information table of FIG. 3 (S804).
[0048]
Since the power supply to the AP 4 is stopped, the ST 7 that cannot receive the beacon signal from the AP 4 searches for the beacon signal of the second connection destination AP 1 or transmits a probe signal to search for the AP 1 and perform authentication. A confirmation and connection sequence are performed (934, 935), and a transition is made to a state where data communication is possible (936).
[0049]
With the above procedure, as shown in FIG. 10, when the power is turned on, the base station that has managed STAs with four APs can manage all STAs with three APs.
[0050]
(Example 2)
The power supply control unit (1106) is added to the AP block diagram of FIG. 4 in the first embodiment, and the block configuration diagram of the AP is changed as shown in FIG.
[0051]
Upon receiving the “AP power supply stop request” from the MFAP control unit (103), the APM (104) notifies the AP 4 of an “authentication release transmission request” in the same procedure as in the first embodiment (S1201). The AP 4 that has received the “authentication release transmission request” transmits an “authentication release notification” to the connected STA and transmits an “authentication release transmission request response” to the APM (104).
[0052]
Upon receiving the “authentication release transmission request response” (S1202), the APM (104) transmits a “power control instruction” to the AP 4 (S1203), and updates the AP operation state information table (FIG. 3) (S1204).
[0053]
Upon receiving the “power control instruction”, the AP 4 notifies the power control unit (1106) of the fact via the MFAP I / F processing unit (1101). The power control unit (1106) that has received the “power control instruction” stops supplying power to the wireless transmission / reception processing unit (1105).
[0054]
As a result, low power consumption is sufficient to drive the AP4, so that the wireless medium can be effectively used while maintaining the power saving effect. Further, when the AP 4 is needed again, an instruction is sent to the power supply control unit (1106), and power is supplied only to the wireless transmission / reception processing unit (1105), whereby the AP 4 can be quickly set to the operation state.
[0055]
【The invention's effect】
According to the present invention, in a wireless communication system including a plurality of wireless terminals and a base station including a plurality of APs that connect wired communication and wireless communication and manage a plurality of wireless terminals, the base station includes the wireless terminal The plurality of APs have the same number of channels and ESS-IDs to be connected as the plurality of APs, and the plurality of APs manage connections with the wireless terminal using different channels and ESS-IDs respectively. Means for identifying the plurality of APs having the smallest number of connected devices when the number of devices becomes equal to or less than a predetermined number, and the base station checks whether the plurality of APs and their connected terminals are transmitting or receiving data. Means for stopping power supply to the specified AP or switching to a low power consumption mode when data communication is not being performed, and the ESS-I having the next highest ESS-ID priority. Searches the AP corresponding to, it makes it possible to obtain efficient utilization and power-saving effect of the wireless medium by providing a means for performing the connection processing.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram in Embodiments 1 and 2 according to the present invention.
[FIG. 2] Radio interference by MFAP [FIG. 3] AP operation state information table [FIG. 4] AP block diagram [FIG. 5] STA configuration diagram [FIG. 6] Flow chart of AP power OFF processing operation in MFAP [FIG. FIG. 8 is a flow chart for AP operation state information acquisition in the management unit. FIG. 8 is a flow chart for AP power OFF instruction operation in the AP management unit. FIG. 9 is a sequence diagram showing the procedure of the first embodiment. 2 system configuration diagram 2
FIG. 11 is an AP configuration diagram according to a second embodiment of the present invention;
FIG. 12 is a flowchart of an AP power control instruction in an AP management unit.
101 MFAP
102 AP operation state monitoring unit 103 MFAP control unit 104 AP management unit

Claims (4)

In a wireless communication system including a plurality of wireless terminals and a base station having a plurality of access point functions for connecting wired communication and wireless communication and managing a plurality of wireless terminals,
The base station has the same number of channels and access point identification codes as the plurality of access point functions, and
Means for managing the connection with the wireless terminal with the plurality of access point functions are respectively different channel and access point identification code,
The base station, when the number of connected wireless terminals is equal to or less than a predetermined number, means for identifying the plurality of access point functions with the least number of connected,
Means for checking whether the plurality of access point functions and their connected terminals are transmitting and receiving data,
A wireless communication system, comprising: means for stopping power supply to the specified access point function unless the specified access point function is performing data communication. In a wireless communication system including a plurality of wireless terminals and a base station having a plurality of access point functions for connecting wired communication and wireless communication and managing a plurality of wireless terminals,
The base station has the same number of channels and access point identification codes as the plurality of access point functions, and
Means for managing the connection with the wireless terminal with the plurality of access point functions are respectively different channel and access point identification code,
The base station, when the number of connected wireless terminals is equal to or less than a predetermined number, means for identifying the plurality of access point functions with the least number of connected,
Means for checking whether the plurality of access point functions and their connected terminals are transmitting and receiving data,
A wireless communication system comprising: means for switching power supply to the specified access point function to low power supply unless the specified access point function is performing data communication. The wireless communication system according to claim 1 or 2,
Means for storing the plurality of channels and the plurality of access point identification codes,
Means for setting a priority for connection to the access point identification code,
A wireless communication system comprising: means for searching for an access point function operating with the access point identification code having a higher priority than the plurality of access point functions, and performing connection processing. The wireless communication system according to claim 1 or 2,
The wireless terminal operates with the access point identification code having the next higher priority than the plurality of access point functions when the broadcast signal transmitted by the access point function in the connected state cannot be received. A wireless communication system comprising means for searching for an access point function to be performed and performing connection processing.

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