JP2001054165A - Data communication system, method and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data communication system that can distribute radio terminal stations to other radio base stations and enhances a utilizing efficiency of a radio medium without the need for special processing to the radio terminal station. SOLUTION: A transmission rate is set externally to a notice information transmission rate storage section 13. This transmission rate reflects a selection state of a radio base station by a radio terminal station. A transmission frame generating section 11 that receives notice information of a transmission object applies processing to the notice information to configure a radio packet specified by the system. A transmission rate control section 12 acquires the transmission rate set to a notice information transmission rate storage section 13 when the transmission object is the notice information and designates it as a transmission rate of the notice information to a transmission processing section 14. The transmission processing section 14 broadcasts the notice information at the designated transmission rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication apparatus for a radio communication system in which a radio terminal station receives broadcast information broadcast from a radio base station and selects a radio base station to be used as an access point. The present invention relates to a data communication device installed in a wireless base station and having a function of controlling a transmission rate of a broadcast information packet broadcast to a wireless terminal station.

[0002]

2. Description of the Related Art Conventionally, there has been a wireless communication system configured to be able to use a plurality of transmission rates in wireless packet communication between a wireless base station and a wireless terminal station. In such a system that can use a plurality of transmission rates, the wireless base station performs communication by selecting an optimal transmission rate for communication with each wireless terminal in accordance with a constantly changing wireless propagation environment. Fallback control becomes possible.

That is, as the transmission rate increases, high-speed communication becomes possible, which is preferable for the user. However, in general, in order to perform communication at an increased transmission rate, the radio propagation environment between the radio stations is good and stable. Need to be. Conversely, if communication is performed at a reduced transmission rate, the communication speed is reduced.However, since a wireless transmission technology that is resistant to the deterioration of the wireless propagation environment can be adopted, the wireless terminal station is located far from the wireless base station. Communication can be performed stably even if the user Therefore, adaptively setting the transmission rate according to the wireless propagation environment between the wireless base station and each wireless terminal station,
Communication between these wireless stations is performed, thereby ensuring high-speed and stable communication of the entire system.

Here, the radio base station periodically broadcasts its own operation information to all radio terminal stations as a broadcast information packet. When broadcasting this broadcast information, an unspecified number of wireless terminal stations need to be able to receive the broadcast information at the same time. Therefore, when broadcasting, the wireless base station always uses a constant transmission rate, and each wireless terminal station Broadcast information at the same transmission rate. In general, a transmission rate defined by the system as a minimum communication rate that can be received by a wireless terminal station located at the farthest distance is used as a transmission rate of broadcast information.

[0005] When the radio base station broadcasts the broadcast information packet, the radio terminal station desiring access to the network selects the radio base station to be used as an access point by itself. The broadcast information packet of each base station is used as a judgment material. At this time, the wireless terminal station not only determines whether or not the base station can be used based on the content of the broadcast information, but also determines the reception status such as the reception level of the packet as a necessary condition for the determination. The selection of the radio base station by the radio terminal station is executed even when the reception status of the selected radio base station with respect to the broadcast information packet has deteriorated due to movement of the radio terminal station or the like. The selection operation in this case is generally called a handover.

FIG. 11 shows a configuration of a conventional data communication apparatus installed in a radio base station for transmitting broadcast information and user data. Broadcast information or user data is input to the transmission frame creation unit 11J as data to be transmitted. The transmission frame creation unit 11J processes each data to form a wireless packet defined by the system, and then inputs the data to the transmission processing unit 14J. Further, the transmission frame creation unit 11J notifies the transmission rate control unit 12J of the type of the processed data (broadcast information, coder data, etc.) by a frame type notification signal S11J.

When the transmission rate control unit 12J recognizes from the frame type notification signal S11J that the data to be transmitted is user data addressed to a certain wireless terminal station,
As described above, a transmission rate predetermined as an optimal transmission rate for communication with each wireless terminal station,
The transmission processing unit 14J according to the transmission rate designation signal S12J
Notify to When the transmission rate control unit 12J recognizes from the frame type notification signal S11J that the data to be transmitted is broadcast information to be broadcast, the transmission rate control unit 12J selects a fixed transmission rate defined by the system,
The transmission processing unit 14J is notified by the transmission rate designation signal S12J. In the transmission processing unit 14J whose transmission rate is specified by the transmission rate specification signal S12J, the wireless packets processed by the transmission frame creation unit 11J are simultaneously wirelessly transmitted at the specified transmission rate.

[0008] Here, as shown in FIG. 12, the broadcast information 61 to 64 by the radio base station 80 includes a broadcast information transmission cycle 6
0 is broadcast periodically. The wireless terminal stations 91 and 92 receive the broadcast information in each broadcast information transmission cycle, and recognize that communication with the wireless base station is possible after receiving the broadcast information. In the example shown in FIG. 12, the broadcast information 61 to 64 is sequentially broadcast over four periods. However, as described above, all of the broadcast information is transmitted at a constant speed and at the lowest speed. Even if the receiving environments (wireless propagation environments) of the wireless terminal stations 91 and 92 are different, the wireless terminal stations 91 and 92 can correctly receive the broadcast information 61 to 64.

[0009]

By the way, in order to avoid a situation where the number of radio terminal stations that select a certain radio base station as an access point increases and the processing amount of the radio base station exceeds its processing capability, In general, a method of distributing wireless terminal stations to other wireless base stations is used. In the above-described conventional wireless communication system, distribution of wireless terminal stations is realized by the following two methods.

As a first method, in the broadcast information broadcast from the radio base station, regulation information for restricting the selection of the radio base station by the radio terminal station is provided. This is a method in which the restriction information is read by a wireless terminal station, and a wireless base station selected by many wireless terminal stations is excluded from options. For example, the use of the wireless base station is rejected by designating all or a part of an identifier for identifying each wireless terminal station at random and broadcasting the broadcast information provided with the restriction information. In this method, not only the radio terminal station that newly selects a radio base station but also the radio terminal station that is already using the radio base station as an access point operates the regulation information that is broadcast. Can respond.

A second method is to make the transmission power of the broadcast information packet of the radio base station variable. That is, if the transmission power is high power, the area where the packet can be received becomes large, and if the transmission power is low power, the area becomes small, and the total number of wireless terminal stations distributed in the area is controlled. it can. In this method, a new wireless terminal station for selecting a wireless base station is not newly targeted, and the entire wireless terminal station including a wireless terminal station already using the wireless base station as an access point is not targeted. Can be decentralized.

However, according to the first method for dispersing wireless terminal stations described above, the wireless terminal station decodes the regulation information received from the wireless base station, and re-establishes the wireless base station according to the information. It is necessary to implement a function to perform special processing for executing selection. In addition, since the wireless terminal station is regulated regardless of the distance and the location of the wireless base station, for example, such as a wireless terminal station located in a location close to the wireless base station, and other wireless base stations In some cases, a wireless terminal station that does not maintain a communicable distance is restricted, and this wireless terminal becomes inaccessible to the network at the moment of the restriction.

Further, according to the second method for dispersing wireless terminal stations described above, the wireless terminal station does not need to perform any special processing for decoding the restriction information. That is,
A wireless terminal station located in the periphery of an area where communication with a wireless base station is possible cannot receive the information when the wireless base station transmits low-power broadcast information. Is performed, and a new wireless base station in the vicinity is searched. Therefore, according to the second method, unlike the first method using the regulation information,
Since the wireless terminal stations targeted for decentralization are limited to those located in the periphery of the area, it is highly likely that the wireless terminal stations are within the communicable area of another wireless base station, and it is impossible to access the network immediately. Not be.

However, in the second method, only the transmission power of the broadcast information is simply increased or decreased, the packet length of the broadcast information does not change, and the time occupying the wireless medium is always constant. For this reason, although there is an effect of dispersing the wireless terminal stations to other wireless base stations, there is no effect of improving the use efficiency of the wireless medium (for example, frequency) by the broadcast information packet. When a wireless medium is shared and used by a plurality of wireless base stations and wireless terminal stations, a carrier sense type wireless access system that starts transmission after confirming use of the medium by a reception level prior to transmission of a wireless packet ( For example, U.S. wireless LAN standard IEEE802.
11: Wireless Mediun Access Control (MAC) and physical
Layer (PHY) Specifications, IEEE Std 802.11, Nov.
1997.), when the transmission power of wireless packets is reduced,
The so-called hidden terminal packet collision problem, in which the number of wireless terminal stations that cannot recognize that the wireless medium is in use increases and the wireless terminal station starts packet transmission while the wireless base station is transmitting the broadcast information packet, Will happen.

[0015] The present invention has been made in view of the above circumstances, and when the number of wireless terminals using a specific wireless base station as an access point increases, the wireless terminal station does not require special processing. It is an object of the present invention to provide a data communication device capable of dispersing wireless terminal stations to other wireless base stations and improving the use efficiency of a wireless medium.

[0016]

In order to solve the above problems, the present invention has the following arrangement. That is, the data communication apparatus according to the present invention selects a wireless base station to be used as an access point by each wireless terminal station (for example, wireless terminal stations 91 and 92 described later) based on broadcast information broadcast from the wireless base station. A radio base station of a radio communication system (for example, a radio communication system shown in FIG. 4 described later) configured to adaptively set a transmission rate used for data communication between a radio base station and a radio terminal station A data communication device installed on the station side, wherein the notification is performed at a transmission rate reflecting a selection state of a wireless base station (for example, a component corresponding to a wireless base station 80 described later) in which the data communication device is installed. Broadcast information transmitting means for broadcasting information (for example, a transmission rate control unit 12, a broadcast information transmission rate storage unit 13, and a transmission processing unit 1 described later)
).

Further, the broadcast information transmitting means includes a transmission rate setting means (for example, a component corresponding to a broadcast information transmission rate storage unit 13 to be described later) for setting a transmission rate reflecting the selection status of the radio base station. When the transmission target is the broadcast information, a transmission rate set by the transmission rate setting means is acquired, and the transmission rate is specified as a transmission rate of the broadcast information. And transmission means for broadcasting the broadcast information at a transmission rate specified by the transmission rate specification means (for example, a component corresponding to a transmission processing unit 14 described later). And

Further, the number of radio packets received by the radio base station where the data communication device is installed is measured to measure the traffic volume of the radio base station, and the transmission rate according to the current traffic volume is determined. It is characterized by further comprising a traffic measuring means (for example, a component corresponding to a traffic measuring unit 23 described later) to be set in the transmission rate setting means.

Further, the number of wireless terminal stations which select the wireless base station in which the data communication apparatus is installed as an access point is monitored to determine the number thereof, and the transmission rate according to the current number is transmitted. A terminal monitoring means (for example, a component corresponding to a management terminal monitoring unit 31 described later) for setting the rate setting means is further provided.

Further, the broadcast information transmitted from the neighboring radio base station is monitored to grasp the transmission rate, and the broadcast information monitoring means sets the transmission rate according to the current transmission rate in the transmission rate setting means. Means (for example, a component corresponding to a neighboring base station transmission rate management unit 41 described later)
Is further provided.

According to the data communication method of the present invention, each radio terminal station selects a radio base station to be used as an access point on the basis of broadcast information broadcast from the radio base station, and establishes a communication between the radio base station and the radio terminal station. A data communication method applied to a wireless base station of a wireless communication system configured to adaptively set a transmission rate used for data communication between the data communication method, and (a) the data communication method is applied. The first step (for example, step STP10 shown in FIG. 2 to be described later, steps STP01 to STP02 to STP10 shown in FIG. 6, or step STP01 shown in FIG. To STP03 to STP10 or steps STP01 to STP04 to S shown in FIG.
(B) the transmission rate set in the first step when the transmission target is the broadcast information, and (b) a second rate that specifies this as the transmission rate of the broadcast information. Steps (for example, elements corresponding to steps STP12 and STP13 shown in FIG. 2 described later)
And (c) a third step of broadcasting the broadcast information at the transmission rate specified in the second step (for example, an element corresponding to step STP14 shown in FIG. 2 described later). I do.

[0022] In the first step, the number of radio packets received by the radio base station to which the data communication method is applied is measured to measure the traffic volume of the radio base station, and the current traffic is measured. It is characterized by including a step of setting a transmission rate according to the amount (for example, elements corresponding to steps STP01 to STP02 shown in FIG. 6 described later).

Further, in the first step, the number of wireless terminal stations that have selected the wireless base station to which the data communication method has been applied as an access point is monitored to ascertain the number, and the number is determined according to the current number. Step of setting a transmission rate (for example, steps STP01 to STP shown in FIG.
(Equivalent to TP03).

Further, in the first step, a step of monitoring broadcast information transmitted from a nearby radio base station, grasping the transmission rate, and setting a transmission rate according to the current transmission rate (for example, (Elements corresponding to steps STP01 to STP04 shown in FIG. 10 described later).

According to the recording medium of the present invention, each radio terminal station selects a radio base station to be used as an access point on the basis of broadcast information broadcast from the radio base station, and a radio communication between the radio base station and the radio terminal station. A recording medium recording a program describing a data communication method applied to a wireless base station of a wireless communication system configured such that a transmission rate used for data communication is adaptively set, a) a first step of setting a transmission rate reflecting a selection state of a radio base station to which the data communication method is applied; and (b) a first step when the transmission target is the broadcast information. A second step of acquiring the set transmission rate and specifying this as the transmission rate of the broadcast information; and (c) the transmission rate specified in the second step. In is obtained by recording a program for executing a third step of broadcasting the broadcast information.

The operation of the present invention will be described below. Generally, when communication is performed at an increased transmission rate, the communication speed needs to be improved, but the wireless propagation environment between wireless stations needs to be good and stable. Conversely, if the communication is performed at a reduced transmission rate, the communication speed will decrease, but the wireless propagation technology that is resistant to the deterioration of the wireless propagation environment can be adopted. Become. The present invention utilizes this property, and when the number of wireless terminal stations that use a certain wireless base station as an access point increases, the wireless terminal station increases the transmission rate of broadcast information for selecting a wireless base station. By changing, the communication area apparently covered by this radio base station is changed.

For example, if the transmission rate is increased, a wireless terminal station located at a long distance, which is inferior to the wireless propagation environment, cannot receive the broadcast information, and the wireless base station transmitting the broadcast information is to be selected. And the number of wireless terminal stations using this wireless base station as an access point decreases. As a result, the wireless terminal station that cannot receive the broadcast information becomes another wireless base station to be selected, and the wireless terminal stations are dispersed. At this time, since the transmission rate of the broadcast information transmitted from the wireless base station is increased, the broadcast information packet length is reduced, and the wireless medium is used efficiently.

Therefore, even if the number of wireless terminals using a specific wireless base station as an access point increases, the wireless terminal station can be added to another wireless base station without requiring any special processing. Can be dispersed, and the efficiency of using the wireless medium can be improved. Further, since the wireless terminal stations can be dispersed while the transmission output is always kept constant, the so-called hidden terminal problem does not occur.

As described above, conventionally, the transmission rate of broadcast information broadcasted by a radio base station to a plurality of radio terminals is constant and uses the minimum speed of the system. Paying attention to the relationship between the communication speed and the communication stability with respect to the transmission rate, it is possible to freely set, change and control the transmission rate of the broadcast information used when the radio terminal station selects the radio base station. The transmission rate of the broadcast information is changed by reflecting the selection status of the radio base station by the radio terminal station.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, common elements are denoted by the same reference numerals, and redundant description is omitted.

<First Embodiment> FIG. 1 shows a configuration of a transmission system of a radio base station to which a data communication apparatus according to a first embodiment of the present invention is applied. The wireless base station having this transmission system constitutes a wireless communication system with a wireless terminal station connected via a wireless line. In this wireless communication system, the wireless base station uses its own operation information as broadcast information,
Broadcasting is periodically performed to all wireless terminal stations, and each wireless terminal station selects a wireless base station to be used as an access point based on broadcast information broadcast from the wireless base station. The transmission rate used for data communication between the wireless base station and the wireless terminal station is set adaptively.

In FIG. 1, as data to be transmitted,
The broadcast information or the user data is transmitted
Is input to The transmission frame creation unit 11 is for processing each input data so as to form a wireless packet defined by the system, and outputs the processed data to the transmission processing unit 14. Further, the transmission frame creating unit 11 sends the type of the processed data (broadcast information, user data, etc.) to the frame type notification signal S1.
At 1, the transmission rate control unit 12 is notified.

The transmission rate control unit 12 designates a transmission rate to a transmission processing unit 14, which will be described later, according to the type of data processed by the transmission frame creation unit 11. For example, when it is recognized from the frame type notification signal S11 that the transmission target is user data, the transmission rate determined as the optimal transmission rate for communication with each wireless terminal is determined by the transmission rate designation signal S12. Notify the transmission processing unit 14.

When the transmission rate control unit 12 recognizes from the frame type notification signal S11 that the transmission target is the broadcast information to be broadcast, it transmits the broadcast information to the broadcast information transmission rate storage unit 13 described later. It is configured to output the rate acquisition signal S13, acquire the transmission rate from the broadcast information transmission rate storage unit 13, and designate this to the transmission processing unit 14 by the transmission rate designation signal S12 as the broadcast information transmission rate. .

Broadcast information transmission rate storage section 13 sets a transmission rate reflecting the selection status of the radio base station in which the data communication apparatus is installed, and sets a transmission rate used when broadcasting the broadcast information. It is for doing. In the broadcast information transmission rate storage unit 13, a transmission rate can be freely set from outside by, for example, a maintenance manager of the radio base station. Therefore,
The transmission rate for broadcasting the broadcast information packet is not fixed, and the transmission rate can be freely changed according to, for example, a maintenance management method.

In the first embodiment, one value is stored in the broadcast information transmission rate storage unit 13 as the broadcast information transmission rate, and this value is externally rewritten to reset the broadcast information transmission rate. It is configured as follows. However, the present invention is not limited to this. For example, a configuration may be adopted in which a plurality of types of transmission rates are set in advance in the broadcast information transmission rate storage unit 13 and appropriately selected from these transmission rates.

The transmission processing unit 14 includes the transmission frame creation unit 1
1 for transmitting the data processed by the transmission rate control unit 1, and when the transmission target is the broadcast information, the transmission rate control unit 1
The broadcast information data processed by the transmission frame creation unit 11 is broadcast at the transmission rate designated by the step 2.

The above-mentioned transmission rate control unit 12, broadcast information transmission rate storage unit 13, and transmission processing unit 14 broadcast broadcast information at a transmission rate reflecting the selection status of the radio base station in which the data communication device is installed. Notification information transmitting means (without a sign). Here, the “selection status of the radio base station” indicates a status in which the radio base station has selected the radio base station as an access point. For example, the traffic volume of the radio base station and the radio This means the number of wireless terminal stations that have selected a base station. Further, the transmission rate of broadcast information transmitted from the wireless base station in which the data communication device is installed is:
Since the “radio base station selection status” is reflected, the “radio base station selection status” may be grasped from the transmission rate of the broadcast information.

Hereinafter, the operation (data communication method) of the data communication apparatus according to this embodiment will be described with reference to the flowchart shown in FIG. Step STP10: The value of the transmission rate of the broadcast information is written into the broadcast information transmission rate storage unit 13 from outside. This transmission rate reflects the selection status of the wireless base station, and is set to a value indicating a higher transmission rate as the number of wireless terminal stations that select the wireless base station as an access point increases.

Step STP11: When the broadcast information is input to the transmission frame creating section 11 in the state where the transmission rate is set in the broadcast information transmission rate storage section 13, the transmission frame creating section 11 receives the broadcast information. The broadcast information is processed to form a wireless packet defined by the system to create a transmission frame, and then output to the transmission processing unit 14. Also, the transmission frame creation unit 1
1 transmits a frame type notification signal S11 indicating that the type of processed data is broadcast information to the transmission rate control unit 1.
2 to notify that the transmission target is broadcast information.

Step STP12: Subsequently, the transmission rate control section 12 acquires the transmission rate set in the broadcast information transmission rate storage section 13. That is, when the transmission rate control unit 12 recognizes that the transmission target is broadcast information based on the frame type notification signal S11 input from the transmission frame creation unit 11, the broadcast information transmission rate storage unit 13
And outputs a broadcast information transmission rate acquisition signal S13 to acquire the transmission rate set in the broadcast information transmission rate storage unit 13.

Step STP13: The transmission rate control section 12 specifies the transmission rate of the broadcast information to the transmission processing section 14. That is, the transmission rate control unit 12 specifies the transmission rate acquired from the broadcast information transmission rate storage unit 13 to the transmission processing unit 14 by the transmission rate designation signal S12 as the transmission rate of the broadcast information to be currently transmitted. .

Step STP14: Subsequently, the transmission processing unit 14 executes a transmission process for broadcasting the broadcast information. That is, the transmission processing unit 14 broadcasts a packet having the broadcast frame of the broadcast information processed by the transmission frame creation unit 11 using the transmission rate specified by the transmission rate control unit 12. As described above, the broadcast information is broadcast at the transmission rate arbitrarily set from the outside.

Next, with reference to FIG. 3, a method of distributing wireless terminal stations by the data communication apparatus according to this embodiment will be described. Also in the present embodiment, the broadcast information from the wireless base station is transmitted periodically according to the broadcast information transmission cycle 60, as in the case shown in FIG. In the example shown in the figure, three types of transmission rates are used as the transmission rates of the broadcast information packets, and rates 1, 2, and 3 are set in ascending order of the transmission rates.

First, the radio base station 80 transmits the broadcast information 71 at the rate 1. In this case, since the transmission rate is low, the wireless terminals 91 and 92 can correctly receive the transmission rate, and then recognize that communication with the wireless base station 80 is possible. Therefore, in this case, both the wireless terminal stations 91 and 92 select the wireless base station 80 as an access point. In this example, there are only two wireless terminal stations, but in this case, the wireless base station 80 is in a state of being selected by an unspecified number of wireless terminal stations.

Next, when it becomes necessary to disperse the radio terminal stations that select the radio base station 80, the radio base station 80 transmits the broadcast information 72 at the rate 2. The transmission rate is set by externally rewriting the value set in the broadcast information transmission rate storage unit 13 described above. In this case, the broadcast information 72 is transmitted at a higher speed than the broadcast information 71, so that the packet length is shortened. As a result, some wireless terminal stations cannot receive the broadcast information 72 depending on the difference in the wireless propagation environment. In this example, the wireless terminal station 91 has received the broadcast information 72, but the wireless terminal station 92 has failed to receive it. Therefore, the wireless terminal station 92 determines that it has moved out of the area of the wireless terminal station 80, performs a normal handover process, and selects another wireless base station.

Further, when the transmission rate of the broadcast information 73 is set to a rate 3 higher than the rate 2, the broadcast information 73 is set.
Is shorter than the packet length of the broadcast information 72, and the wireless terminal station 91 also fails to receive the broadcast information. That is, the wireless base station 80 can cause the wireless terminal 91 to perform the handover by transmitting the broadcast information 73 at a higher rate 3. At this point, there are no radio terminal stations under the control of the radio base station 80. However, if the radio base station 80 transmits the next broadcast information 74 again at the rate 1, it can be selected from other radio terminal stations. Nature occurs. As described above, by changing the transmission rate, radio terminals can always be dispersed, and the degree of dispersion of the radio terminal stations can be controlled in accordance with the value of the transmission rate.

Next, the state of the above-mentioned method for dispersing wireless terminal stations will be described with reference to FIG. This figure (a) shows a state before the transmission rate of the broadcast information is changed, and the transmission rates of the broadcast information transmitted from the radio base station 80 and the other radio base stations 81 are both set to rate 1. ing. FIG. 2B shows a state after the transmission rate of the broadcast information is changed. The transmission rate of the broadcast information transmitted from the radio base station 80 is changed to rate 2 and the radio base station 81 is changed. The transmission rate of broadcast information transmitted from is rate 2
It is still.

The two wireless base stations 80 and 81 connected to the network are base stations that can be used as access points by both wireless terminal stations. Wireless base stations 80, 81
As shown in FIG. 12A, when both pieces of broadcast information are transmitted at a transmission rate of 1, there are mutually overlapping areas as communicable areas. In this example, both the wireless terminal station 92 located in the overlapped area and the wireless terminal 84 existing in the area of the wireless base station 80 have selected the wireless base station 80. In such a case, since the processing amount of the wireless base station 80 is larger than that of the wireless base station 81, it is desirable to disperse the wireless terminal stations.

As shown in FIG. 5B, the radio base station 80
When the transmission rate of the broadcast information transmitted from is increased, when the broadcast information packet is transmitted at a high speed, the communicable area of the wireless base station 80 is apparently narrowed, and the overlap area as shown in FIG. . As a result, the wireless terminal station 92 recognizes that it has moved out of the area of the wireless base station 80 and has gone out of this area, and reselects another adjacent wireless base station 81 as an access point by handover processing. As a result, the wireless terminal stations are distributed to both wireless base stations, and efficient wireless communication can be performed.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS. FIG.
2 shows a configuration of a transmission system of a radio base station to which the data communication device according to the second embodiment is applied. In this configuration, the reception information of the radio base station is used to determine the transmission rate when broadcasting the broadcast information packet.
Specifically, the traffic amount of the radio base station is obtained from the reception information, and this is reflected on the transmission rate of the broadcast information as the selection status of the radio base station.

In FIG. 5, a reception processing section 21 is for receiving a wireless reception packet input via a wireless line, and a reception data processing section 22 is for processing a received wireless reception packet. The reception processing unit 21 and the reception data processing unit 22
Is provided in a conventional device as a receiving system device of a wireless base station.

The traffic measuring unit 23 measures the number of radio packets received by the radio base station in which the data communication device is installed, measures the traffic volume of the radio base station, and determines the traffic volume of the radio base station according to the current traffic volume. The transmission rate is set in the transmission rate setting means. FIG.
Are the same as those shown in FIG. 1 according to the first embodiment.

The operation of the second embodiment will be described below with reference to the flowchart shown in FIG. Step STP01: The wireless reception packet input via the wireless line is processed by the reception processing unit 21, and then input to the reception data processing unit 22 for analyzing the reception data. Here, the reception processing unit 21 notifies the traffic measurement unit 23 by the received packet number notification signal S21 every time a packet is received.

Step STP02: Upon receiving the received packet number notification signal S21, the traffic measuring unit 23 analyzes the number of packets received by the radio base station as a traffic amount. Then, the transmission rate reflecting the current traffic amount is notified to the notification information transmission rate storage unit 13 by the notification information transmission rate notification signal S22, and the transmission rate corresponding to the current traffic amount is reported as the transmission rate of the notification information. It is set in the information transmission rate storage unit 13. At this time, the traffic measuring unit 23 controls to increase the transmission rate when the traffic amount increases, and to decrease the transmission rate when the traffic amount decreases.

Steps STP10 to STP14: Hereinafter,
Broadcast information is broadcast at the transmission rate set in the broadcast information transmission rate storage unit 13 in the same manner as in the first embodiment.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIGS. FIG.
9 shows a configuration of a transmission system of a wireless base station to which the data communication device according to the third embodiment is applied. In the transmission system of the radio base station according to the third embodiment, in the configuration shown in FIG. 5 described above, instead of the traffic measurement unit 23, a radio base station in which the data communication device is installed is selected as an access point. Monitor the number of wireless terminal stations
It is provided with a management terminal monitoring unit 31 for setting the transmission rate according to the current number in the broadcast information transmission rate storage unit 13.

The transmission system of the radio base station according to the third embodiment determines the transmission rate of the broadcast information by using the reception information of the radio base station, as in the second embodiment. However, the second embodiment differs from the second embodiment in that the number of wireless terminal stations that select the wireless base station as an access point is reflected in the transmission rate of broadcast information.

The operation of the third embodiment will be described below with reference to the flowchart shown in FIG. Step STP01: Similarly to the above-described second embodiment, a wireless reception packet input via a wireless line is subjected to reception processing by a reception processing unit 21, and then input to a reception data processing unit 22 for analysis of reception data. Is done. Here, the reception processing unit 21 grasps the identifier of the wireless terminal station of the transmission source of the packet from the analyzed reception data, and each time the packet is received, the management terminal monitoring unit 3
Notify 1.

Step STP03: In response to the received packet number notification signal S31, the management terminal monitoring unit 31 analyzes the identifier of the wireless terminal station and increases or decreases the number of wireless terminal stations using the wireless base station as an access point. It manages and notifies the transmission rate of the broadcast information packet to the broadcast information transmission rate storage unit 13 by the broadcast information transmission rate notification signal S22, and transmits the broadcast rate according to the current traffic amount as the broadcast information transmission rate. Rate storage unit 1
Set to 3. At this time, the management terminal monitoring unit 31 increases the transmission rate when the number of wireless terminal stations using the wireless base station as an access point increases, and decreases the transmission rate when the number of wireless terminal stations decreases. To control.

Steps STP10 to STP14: Hereinafter,
Broadcast information is broadcast at the transmission rate set in the broadcast information transmission rate storage unit 13 in the same manner as in the first embodiment.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 9 shows a configuration of a transmission system of a radio base station to which the data communication device according to the fourth embodiment is applied. Embodiment 4
In the configuration shown in FIG. 5, the transmission system of the radio base station monitors broadcast information transmitted from a nearby radio base station in place of the traffic measurement unit 23 to grasp the transmission rate, It is provided with a neighboring base station transmission rate management unit 41 for setting a transmission rate according to the current transmission rate in the broadcast information transmission rate storage unit 13. The information of the wireless base station is used.

The operation of the fourth embodiment will be described below with reference to the flowchart shown in FIG. Step STP01: Similarly to the above-described second embodiment, a wireless reception packet input via a wireless line is subjected to reception processing by a reception processing unit 21, and then input to a reception data processing unit 22 for analysis of reception data. Is done. Here, the reception processing unit 21 determines whether or not the data transmitted from the nearby wireless base station is the broadcast information based on the analyzed reception data. If the data is broadcast information,
The transmission rate of the broadcast information packet is notified to the neighboring base station transmission rate management unit 41 by the neighboring base station transmission rate notification signal S41.

Step STP03: Upon receiving the adjacent base station transmission rate notification signal S41, the adjacent base station transmission rate management section 41 analyzes the transmission rate of the broadcast information packet of the neighboring radio base station, and determines the current neighboring radio base station. The status of the station with respect to the terminal decentralization control is grasped, the transmission rate of the broadcast information packet is notified to the broadcast information transmission rate storage unit 13 by the broadcast information transmission rate notification signal S22, and the transmission rate according to the current transmission rate is notified. Is set in the broadcast information transmission rate storage unit 13 as the broadcast information transmission rate. At this time, the adjacent base station transmission rate management unit 41 increases the transmission rate if the neighboring radio base station uses a low transmission rate, and conversely, increases the transmission rate if the neighboring radio base station uses a high transmission rate. Control to lower.

Steps STP10 to STP14: Hereinafter,
Broadcast information is broadcast at the transmission rate set in the broadcast information transmission rate storage unit 13 in the same manner as in the first embodiment.

According to the configuration of the fourth embodiment, a plurality of radio base stations can interact with each other to decentralize radio terminal stations. In the fourth embodiment, the broadcast information packet is directly received to obtain information on the transmission rate used by the nearby radio base station. However, the present invention is not limited to this. For example, as shown in FIG. In such a configuration, information such as the transmission rate of the wireless base station can be exchanged between the wireless base stations via the network. However, in this case, it is necessary to define a dedicated signal to be sent to the network for information exchange.

Further, according to each of the above-described embodiments, the number of radio terminal stations using a certain radio base station as an access point increases, and the radio base station is used to avoid a case where the processing capability of the radio base station is exceeded. In the method of distributing the terminal stations to other wireless base stations, it is not necessary to provide a special function to the wireless terminal side.

According to each of the above-described embodiments, when the area communicable with the radio base station is reduced and the radio terminal stations are dispersed, the broadcast information transmission is changed to a high transmission rate. The packet length of the information can be shortened, and the occupation time of the wireless medium by the packet can be shortened. At this time, the transmission output is always constant, so that the hidden terminal problem hardly occurs, and radio packet collision does not occur.

Therefore, by using the data communication apparatus according to the embodiment of the present invention, it is possible to improve the use efficiency of the wireless medium (for example, frequency) without adding any new function to the wireless terminal station, and to improve the wireless communication efficiency. Terminal stations can be decentralized.

Although the first to fourth embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and there are design changes and the like that do not depart from the gist of the present invention. Are also included in the present invention. For example, in the above-described embodiment, the broadcast information transmission rate is set in the broadcast information transmission rate storage unit 13. However, the function of the broadcast information transmission rate storage unit 13 is taken into the transmission rate control unit 12, and transmitted. The transmission rate may be set directly to the rate control unit 12.

In the above-described embodiment, after setting the transmission rate (step STP10), a transmission frame is created (step STP11), and the transmission rate is obtained and specified (steps STP12, STP13). However, the order of these steps is not limited to this, and can be appropriately changed.

Further, in the above-described embodiment, the present invention is realized on hardware as a data communication device. However, the present invention is not limited to this, and the present invention may be realized on software. In this case, the data communication device and the method according to the present invention can be constructed on a computer by reading the program for executing the steps performed by the data communication device according to each of the above-described embodiments into the computer. If this program is recorded on a computer-readable recording medium, the data communication and the method according to the present invention can be constructed on any computer that can access this recording medium.

[0073]

As described above, according to the present invention, the broadcast information is broadcast at the transmission rate reflecting the selection status of the radio base station by the radio terminal station. When the number of wireless terminals used as access points increases, wireless terminal stations can be distributed to other wireless base stations without requiring special processing, and the efficiency of use of wireless media can be improved. Can be improved.

Further, a transmission rate reflecting the selection status of the radio base station is set, and when the transmission target is the broadcast information, the transmission rate set in the transmission rate setting means is obtained, and the broadcast rate is set. Since the broadcast information is broadcast at the specified transmission rate, the broadcast information can be broadcast at the transmission rate reflecting the selection status of the wireless base station by the wireless terminal station. Become.

Further, the number of radio packets received by the radio base station is measured to measure the traffic volume of the radio base station, and a transmission rate corresponding to the current traffic volume is set as the transmission rate of the broadcast information. Therefore, when the traffic volume at a specific wireless base station increases, it is possible to distribute the wireless terminal stations to other wireless base stations.

Further, the number of radio terminal stations that have selected the radio base station as an access point is monitored to determine the number thereof, and a transmission rate according to the current number is set as the transmission rate of the broadcast information. Accordingly, when the number of wireless terminals using a specific wireless base station as an access point increases, it is possible to disperse wireless terminal stations to other wireless base stations.

Further, the broadcast information transmitted from a nearby radio base station is monitored to grasp the transmission rate, and a transmission rate corresponding to the current transmission rate is set as the transmission rate of the broadcast information. Therefore, it is possible to disperse the wireless terminal stations according to the selection status of the neighboring wireless base stations.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a data communication device according to a first embodiment of the present invention;

FIG. 2 is a flowchart showing an operation flow of the data communication device according to the first embodiment of the present invention;

FIG. 3 is a diagram for explaining a concept of a method for distributing wireless terminal stations by the data communication device according to the first embodiment of the present invention;

FIG. 4 is a diagram for explaining distribution of wireless terminal stations by the data communication device according to the first embodiment of the present invention;

FIG. 5 is a block diagram illustrating a configuration of a data communication device according to a second embodiment of the present invention;

FIG. 6 is a flowchart illustrating a flow of an operation of the data communication device according to the second embodiment of the present invention;

FIG. 7 is a block diagram illustrating a configuration of a data communication device according to a third embodiment of the present invention;

FIG. 8 is a flowchart illustrating a flow of an operation of the data communication device according to the third embodiment of the present invention;

FIG. 9 is a block diagram showing a configuration of a data communication device according to a fourth embodiment of the present invention.

FIG. 10 is a flowchart illustrating a flow of an operation of the data communication device according to the fourth embodiment of the present invention;

FIG. 11 is a block diagram illustrating a configuration of a wireless base station according to the related art.

FIG. 12 is a diagram for explaining a broadcast information packet transmission method (operation of a conventional device) according to the related art.

[Explanation of symbols]

11: transmission frame creation unit 12: transmission rate control unit 13: broadcast information transmission rate storage unit 14: transmission processing unit 21: reception processing unit 22: reception data processing unit 23: traffic measurement unit 31: management terminal monitoring unit 41: neighborhood Base station transmission rate management unit 60: Broadcast information transmission cycle 61 to 64, 71 to 71: Broadcast information 80, 81: Wireless base station 91, 92: Wireless terminal station S11: Frame type notification signal S12: Transmission rate designation signal S13: Broadcast information transmission rate acquisition signal S21: Received packet number notification signal S22: Broadcast information transmission rate notification signal S31: Terminal number notification signal S41: Adjacent base station transmission rate notification signal STP10 to STP14, STP01 to STP04: Step

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 5K033 AA03 CB01 CB06 CB13 DA03 DA19 DB18 EA06 EA07 5K067 AA11 BB21 CC08 EE02 EE10 EE22 EE72 GG04 GG11

Claims (10)

[Claims] 1. A wireless base station that selects a wireless base station to be used as an access point based on broadcast information broadcast from a wireless base station, and is used for data communication between the wireless base station and the wireless terminal station. A data communication device installed on a wireless base station side of a wireless communication system configured such that a transmission rate to be set is adaptively set, and the selection status of the wireless base station on which the data communication device is installed is reflected. And a broadcast information transmitting means for broadcasting the broadcast information at the set transmission rate. 2. The broadcast information transmitting unit includes: a transmission rate setting unit configured to set a transmission rate reflecting a selection state of the radio base station; and a transmission rate setting unit when a transmission target is the broadcast information. A transmission rate designating unit that acquires a set transmission rate and designates this as a transmission rate of the broadcast information; and a transmission unit that broadcasts the broadcast information at a transmission rate designated by the transmission rate designating unit. The data communication device according to claim 1, wherein: 3. The traffic rate of the radio base station is measured by measuring the number of radio packets received by the radio base station in which the data communication device is installed, and the transmission rate according to the current traffic volume is determined. 3. The data communication apparatus according to claim 2, further comprising a traffic measuring unit that sets the transmission rate setting unit. 4. A wireless terminal station, which has selected a wireless base station in which the data communication apparatus is installed as an access point, monitors the number of the wireless terminal stations, grasps the number of the wireless terminal stations, and determines a transmission rate according to the current number. 3. The data communication device according to claim 2, further comprising a terminal monitoring unit that sets the setting unit. 5. Broadcast information monitoring means for monitoring broadcast information transmitted from a nearby radio base station to grasp its transmission rate, and setting a transmission rate according to the current transmission rate in said transmission rate setting means. The data communication device according to claim 2, further comprising: 6. A wireless base station which selects a wireless base station to be used as an access point based on broadcast information broadcast from the wireless base station, and is used for data communication between the wireless base station and the wireless terminal station. A data communication method applied to a wireless base station of a wireless communication system configured such that a transmission rate to be set is adaptively set, and (a) a selection state of a wireless base station to which the data communication method is applied And (b) acquiring the transmission rate set in the first step when the transmission target is the broadcast information, and transmitting the broadcast rate to the broadcast information. (C) a third step of broadcasting the broadcast information at the transmission rate specified in the second step. Data communication method characterized in that. 7. In the first step, the number of radio packets received by the radio base station to which the data communication method is applied is measured to measure the traffic volume of the radio base station, and the current traffic is measured. 7. The data communication method according to claim 6, wherein a transmission rate according to the amount is set. 8. In a first step, the number of wireless terminal stations that have selected the wireless base station to which the data communication method has been applied as an access point is monitored to ascertain the number, and the number is determined according to the current number. The data communication method according to claim 6, wherein a transmission rate is set. 9. The first step is characterized in that broadcast information transmitted from a nearby radio base station is monitored, the transmission rate is grasped, and a transmission rate according to the current transmission rate is set. 7. The data communication method according to claim 6, wherein: 10. A wireless base station which selects a wireless base station to be used as an access point based on broadcast information broadcast from the wireless base station, and is used for data communication between the wireless base station and the wireless terminal station. A recording medium storing a program describing a data communication method applied to a wireless base station of a wireless communication system configured such that a transmission rate is adaptively set, wherein: (a) the data communication method; A first step of setting a transmission rate reflecting a selection state of a radio base station to which is applied, and (b) determining a transmission rate set in the first step when the transmission target is the broadcast information. A second step of acquiring and specifying this as the transmission rate of the broadcast information; and (c) broadcasting the broadcast information at the transmission rate specified in the second step. And a computer-readable recording medium recording a program for executing the third step of performing a broadcast.