JPH11225145A - Radio lan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve communication efficiency by preventing interference to another cell terminal. SOLUTION: The radio LAN consists of pluralities of servers, pluralities of terminals 20 provided corresponding to each of pluralities of the servers and making radio transmission by a radio channel with a corresponding server provided to a range (cell) within the reach of the radio wave outputted form the corresponding server. Each terminal 20 is provided with a transmission control means 40 that decides a transmission signal based on an RSSI signal and a correlation output. Each terminal 20 makes transmission to the corresponding server with a transmission output decided by the transmission control means 40 provided to each.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless LAN, and more particularly, to a wireless LAN having improved communication efficiency by preventing interference with terminals of other cells.

[0002]

2. Description of the Related Art A wireless LAN (local area network) has a great advantage that no wiring is required because its transmission medium is a space. On the other hand, a radio wave (visible light, infrared light, radio wave) which is an actual transmission medium output from the server (or the wireless adapter) cannot be output very large due to various restrictions. The range (cell) within which radio waves can reach from one server is determined by the output limitation of this server. Therefore, in order to realize a state in which communication is possible without omission by a wireless LAN in a certain area (area), a plurality of servers A to C need to be provided as shown in FIG. That is, it is necessary to divide the area by the cell method.

Since the actual transmission medium in a wireless LAN is a radio wave and the communication method is a broadcast method, the shape of the cell boundary is circular. Therefore, in order to realize a state in which communication is possible without omission in a certain area by the wireless LAN, adjacent cells are in a state of being overlapped with each other near a cell boundary as shown in FIG.

Therefore, when there are a plurality of cells, it is necessary to process radio signals from adjacent cells as unnecessary signals. For this purpose, each terminal must be able to discriminate between a signal from a server of its corresponding cell and a signal from a server of an adjacent cell. As a method of this determination,
For example, there are a method using a different frequency for each cell, and a method for determining a difference between cells based on a difference between IDs.

[0005]

As described above, when the area is divided by the cell method, as shown in FIG.
In the vicinity of the boundary between both cells, terminal X may be in a transmitting state and terminal Y may be in a receiving state. In this case, if a method of discriminating a cell difference based on the ID is adopted, the signal from the terminal X interferes with the terminal Y because the signal from the terminal X has a large strength because the frequency does not differ between the cells. That is, the terminal Y that the terminal Y should originally receive has its own LA
It becomes impossible to receive a signal from N servers C (this is referred to as a near-far problem in this specification). Normally, communication between terminals in different cells is impossible, so that it is not possible to know at what timing terminal X ends communication. For this reason, the transmission efficiency in the wireless LAN is reduced.

[0006] When an area is divided by a cell system, as shown in FIG.
And the terminal Y, the distance Rbc between the terminal and the respective servers rather than the line-of-sight distances Rb and Rc between the terminal and each server.
May be smaller. For this reason, if a method of discriminating the difference between cells based on the ID is adopted, since the frequency does not differ between cells, for example, when the terminal X performs communication in the area B, the server C performs communication in the area C. The terminal Y senses the radio wave from the terminal X even if it is not performing. Normally, each terminal has a carrier sense function, and has a function of forgoing transmission when radio waves are sensed in the communication band by this function. As a result, even if the terminal Y attempts to transmit, the terminal Y forgoes the transmission (this is also referred to as a perspective problem in this specification). Therefore, regarding the terminal Y, communication cannot be performed, and the communication efficiency is reduced.

[0007] Since the wireless LAN is characterized in that the terminal can be moved freely within a certain range, the communication environment seen from the terminal changes easily. For this reason, the above-mentioned perspective problem is a problem of wireless LA.
This problem easily occurs in N. For example, as a result of moving the terminal, a case where the terminal is too close to a terminal in another cell or a case where an obstacle (other office equipment) exists between the terminal and the server.

[0008] It is an object of the present invention to provide a wireless LAN with improved communication efficiency by preventing interference with terminals in other cells. Another object of the present invention is to provide a wireless LAN that solves the near-far problem when determining the difference between cells based on an ID.

[0009]

FIG. 1 is a block diagram showing the principle of the present invention, and shows the configuration of a wireless LAN according to the present invention. This wireless LAN includes a plurality of servers 10 (10A to 10C),
A plurality of terminals 20 provided for each of the plurality of servers 10, provided in a range (cell) 30 where radio waves output from the corresponding server 10 reach, and wirelessly communicated with the corresponding server 10. Terminals 20 that transmit by
Consists of Each of the terminals 20 includes a transmission control unit 40 that determines a transmission output based on the RSSI signal and the correlation signal. Each of the terminals 20 has its own transmission control means 40
Is transmitted to the corresponding server 10 with the determined transmission output.

According to the wireless LAN of the present invention, each of the terminals 20 determines the transmission output of the terminal 20 by using the RSSI signal and the correlation signal in its transmission control means 40. The RSSI signal and the correlation signal, which will be described later in detail, represent the communication environment in which the terminal 20 is located by numerical values. Therefore, according to the wireless LAN of the present invention, each of the terminals 20 can select a transmission output most suitable for the communication environment in which the terminal 20 is located.

Thus, as described above, even when terminal X is in the transmission state and terminal Y is in the reception state, the signal from terminal X is transmitted to terminal Y because terminal X selects the optimum transmission output. Can be prevented. Thus, the terminal Y can receive a signal from the server C of the corresponding wireless LAN, thereby substantially preventing a decrease in transmission efficiency. Further, as described above, even if the distance between the terminal X and the terminal Y is small, since the terminal X selects the optimum transmission output, it is substantially necessary for the terminal Y to sense the radio wave from the terminal X. Can be prevented. That is, the perspective problem can be solved. Accordingly, it is possible to prevent the terminal Y from forgoing the communication with the server C, and it is possible to prevent the communication efficiency from decreasing.

[0012]

FIG. 2 shows the configuration of a wireless LAN.
The wireless LAN to which the present invention is applied is mainly constructed by the server 10, as shown in FIG. When distinguishing each server 10, the servers 10A, 1
0B..., For example, a cell corresponding to the server 10A is represented as a cell 30A.

The servers 10A and 10B are connected to the main LAN 50.
Build a small wireless LAN without being connected to The wireless LAN includes the servers 10A and 10B and a terminal 20 that performs wireless transmission using predetermined radio waves (visible light, infrared light, radio waves) between the servers 10A and 10B without using an optical fiber or the like. That is, the server 10A and the plurality of terminals 20 corresponding thereto constitute one wireless LAN.
The same applies to the server 10B.

The main LAN 50 is a wired LAN using an optical fiber or a coaxial cable. In the main LAN 50, a plurality of servers 1 provided separately from the servers 10A and the like are provided.
0D is connected. The terminal 20D, which is the client, is connected to the server 10D by wire. The terminal 20D is, for example, a personal computer. Basic LAN 50
Is connected to another network via a public network, for example.

The servers 10A and 10B transmit a predetermined radio wave (for example,
(2.4 GHz band). The terminal 20 is, for example, a personal computer. The ranges (cells) 30A and 30B of the radio waves of the servers 10A and 10B overlap with each other. The distance between the terminal 20X that is a client of the server 10A and the terminal 20Y that is a client of the server 10B is short. In the present invention,
For example, by adjusting the intensity of the radio wave output from the terminal 20X to an appropriate value, the reception of the signal by the terminal 20Y is prevented.

To this end, the terminal 20 includes a transmission control means 40 for determining a transmission output based on the RSSI signal and the correlation output, as described later with reference to FIG. Terminal 2
0 indicates that the transmission output determined by the transmission control means 40 is transmitted to the corresponding server 10. Thereby, the transmission output in each terminal 20 is adjusted to an appropriate value.

Since there are a plurality of cells 30 of the wireless LAN, the terminal 20 discriminates a signal from the server 10 corresponding to itself and other signals by a known method. That is,
An I code defined by spreading an ID code (PN pattern) in the transmission data using spread spectrum.
D is detected and discriminated based on the difference. The ID is unique for each server 10. When receiving a signal from a server other than the corresponding server 10, the terminal 20 processes (discards) the signal as an unnecessary signal.

As shown in FIG. 2B, the wireless LAN to which the present invention is applied is a wireless LAN using a predetermined radio wave between a wireless adapter 60 connected to the main LAN 50 by wire. May be configured with the terminal 20 that performs transmission. In this case, the wireless adapter 60 corresponds to the server 10. Therefore, in this specification, the server 10 is a wireless adapter 60 and an equivalent thereof, for example, a repeater that constitutes a wireless LAN (a relay that receives a radio wave from the wireless adapter 60 or the server 10 and transmits it to the terminal 20). )including. Although not shown, a plurality of wireless adapters 60 are provided so as to be connected to the main LAN 50, and the radio wave reachable areas (cells) 30 overlap each other. In this case, according to the present invention, each wireless adapter 60 adjusts its transmit power to an appropriate value.

FIG. 3 shows the configuration of the terminal 20 of the wireless LAN, and particularly shows the configuration of the transmission control means 40 in the terminal 20. The transmission control means 40 operates as transmission output determination means for determining the transmission output of the terminal 20.

In the terminal 20, it is assumed that the transmission / reception changeover switch 9 is in the reception state (FIG. 3 shows a case where the changeover switch 9 is in the transmission state). When the changeover switch 9 is in the receiving state, when a signal receiving unit (antenna and detector) (not shown) receives a radio wave in a predetermined frequency band, an electric signal corresponding to the received radio wave is transmitted to the AGC (AGC) via the down converter 1. Automatic gain adjuster) 2. When the intensity of the received radio wave (electric signal corresponding to) is low, the AGC 2 amplifies and outputs the received radio wave (electric signal corresponding to) according to the degree.
The amplified output of AGC 2 is input to matched filter (MF) 3 and despreading circuit 4.

AGC2 has an RSS in accordance with the degree of amplification.
Outputs the I signal. The value of the RSSI signal increases as the intensity of the received radio wave decreases (in proportion to the degree of amplification).
Therefore, the RSSI signal is a signal indicating the strength of the received radio wave, and the strength of the received radio wave can be known by referring to the value of the RSSI signal. The RSSI signal is input to the transmission output control circuit 5.

The MF 3 analyzes the ID code spread using the spread spectrum in the data of the received radio wave, and when the received radio wave is a signal from the server 10 corresponding to itself, the MF 3 amplifies the output of the AGC 2. And outputs a correlation output signal corresponding to the magnitude of. On the other hand, if the received radio wave is not a signal from the server 10 corresponding to itself, the MF 3 does not output a correlation output signal. The output of MF3 is input to demodulation / PN control circuit 6.

The demodulation / PN control circuit 6 inputs a predetermined PN pattern (ID code) to the despreading circuit 4. Using the PN pattern, the despreading circuit 4 removes the ID code spread from the amplified output from the AGC 2 in the received data by spectrum spreading, and inputs the result to the demodulation / PN control circuit 6. Demodulation / PN control circuit 6 demodulates the output of despreading circuit 4 and outputs a predetermined demodulated signal.

The demodulation / PN control circuit 6 synchronizes using the correlation output signal from the MF 3. The correlation signal is input to the transmission output control circuit 5. The correlation signal is a signal having a different peak value according to the magnitude of the correlation output signal, while the demodulated signal is a pulse signal having the same peak. Since the correlation output signal is a signal corresponding to the magnitude of the amplified output of AGC2, the correlation signal is also a signal corresponding to the magnitude of the amplified output of AGC2.

The transmission output control circuit 5 receives the R signal from the AGC 2
A transmission output control signal is formed based on the SSI signal and the correlation signal from the demodulation / PN control circuit 6. The transmission output control circuit 5 refers to the file 7 for forming the transmission output control signal. The transmission control means 40 is composed of the transmission output control circuit 5 and the file 7. The formation of the transmission output control signal will be described later with reference to FIGS.

In the case where the correlation signal is being output, the transmission output control signal is designed to increase the transmission output when the RSSI signal from the AGC 2 is large (the intensity of the received radio wave is low), and the communication state is not good. When the RSSI signal is small (the intensity of the received radio wave is strong), the communication state is good and the signal is such that the transmission output is kept as it is. When the communication state is good, the transmission output control signal may be a signal that reduces the transmission output.

On the other hand, when the correlation signal is not output and the RSSI signal is output, since the correlation signal is not output, the received signal is not a signal from the corresponding server 10, but It can be determined that the signal is a signal from the nearby terminal 20 and is an interference wave. Therefore, the transmission output control signal is a signal that increases the transmission output.

The transmission output control signal is supplied to a signal transmission means (for example, a power amplifier) 8. Thereby, the magnitude of the output of the signal transmitted by the signal transmitting means 8 is set to an appropriate value according to the communication environment where the terminal 20 is located. Separately from this, a transmission signal in which an ID code is embedded in data by spectrum spreading and modulated by a transmission signal processing circuit (not shown) is supplied to the signal transmission means 8. After the changeover switch 9 is set to the transmission state, the signal transmission unit 8 transmits data to the corresponding server 10 with the set transmission output.

FIGS. 4 and 5 show terminals 2 as clients.
FIG. 4 shows a client default file 71, and FIG. 5 shows a client file 72. The client default file 71 indicates that the terminal 20 has not communicated at all (or has not communicated for a predetermined period of time), and the client file 72 indicates that the terminal 20 has not communicated. Are performed (or when communication is performed within a predetermined time), each is referred to by the transmission output control circuit 5 to determine the transmission output.

The client default file 71 stores a received (signal) value and a corresponding transmitted (output) value. The value stored in the client default file 71 is an average value empirically obtained for an environment in which a wireless LAN is constructed, and is an appropriate value in most cases. Since the strength of the received radio wave can be known by referring to the value of the RSSI signal, the transmission output control circuit 5 obtains the value of the received signal from the value of the RSSI signal, and uses this to calculate the value of the client default file 71.
To obtain the value (magnitude) of the corresponding transmission output, and use that value as the value of the transmission output in the communication.

The client file 72 stores a request value, a reception average value, and a transmission average value. The request value is the value of the received signal obtained from the value of the RSSI signal in the immediately preceding communication, the average reception value is the average value of all the received signals in one job of the immediately preceding communication, and the average transmission value is all of the values in one job of the immediately preceding communication. Are the average values of the transmitted signals of

The transmission output control circuit 5 compares the value of the received signal obtained from the value of the RSSI signal in the communication with the request value of the client file 72, and determines the value of the transmission output based on the result. If the two are equal, it is determined that the communication environment has not changed from the immediately preceding communication, and the request value of the client file 72 is used as the value of the transmission output. As a result, an appropriate transmission output value can be obtained without performing any other processing.

When the two are different, the transmission output control circuit 5 determines the transmission output as follows. That is,
When the value of the received signal of the communication is smaller than the request value, the communication environment is worse than that of the immediately preceding communication. Therefore, the transmission output is set to a value larger than the request value. On the other hand, when the value of the reception signal of the communication is larger than the request value, the communication environment is better than that of the immediately preceding communication, and the request value is set as the value of the transmission output. As a result, the transmission output is not unnecessarily increased, so that the communication of the other terminals 20 is not unnecessarily obstructed.

When the transmission output is set to a value larger than the request value, the transmission output control circuit 5 obtains a value obtained by adding "+1" to the value of the reception signal of the communication, and uses this value to store the client default file 71 again. The value (magnitude) of the corresponding transmission output is obtained by referring to the value, and the value is set as the value of the transmission output in the communication. Alternatively, the transmission output control circuit 5
Let the value of the transmission output be the value of the transmission average of the client file 72. As a result, the transmission can be performed quickly, and the transmission output is not unnecessarily increased, so that the communication of the other terminals 20 is not unnecessarily obstructed.

When reception and transmission are performed, for each job, the transmission output control circuit 5 uses the received signal value and the transmitted signal value to generate all received signals and transmitted signals in the job. An average value is obtained, and the reception average and transmission average of the client file 72 are updated.

In the wireless LAN according to the present invention, the transmission output adjustment processing in the terminal 20 described above is performed by the server 1.
The same applies to the 0 side. For this, the server 10
Similarly to the terminal 20, the transmission control means 40 shown in FIG.
Is provided.

The server 10 stores the file 7 in FIG.
The server file 73 and the server default file shown in FIG. The server default file is the same as the client default file 71 shown in FIG. The server file 73 stores a request value and a transmission value and a reception value for each terminal (client) 20. The request value is the value of the received signal obtained from the value of the RSSI signal in the immediately preceding communication, the transmission value is the average value of all the transmission signals in one job of the immediately preceding communication for the terminal 20, and the received value is the value for the terminal 20. This is the average value of all received signals in one job of the immediately preceding communication.

The operation of the wireless LAN according to the present invention will be described using the server 10B and the terminal 20X in FIG. 1 as an example. Server 1
0B sends out a signal (release signal) indicating that communication is not being performed. The level of this signal is
All terminals 20 (within cell 30B) corresponding to B are empirically sized to receive this.

When the terminal 20X corresponding to the server 10B receives this, the AGC 2 obtains and outputs an RSSI signal from the received signal which is the release signal. At this time, since the terminal 20X is a terminal corresponding to the server 10B, the MF
3 outputs a correlation output signal. Therefore, the transmission output control circuit 5 stores the reception signal value obtained from the RSSI signal as a request value in the client file 72, and determines the transmission output by referring to the client default file 71 using the reception signal value, This transmission output is used to transmit to the server 10B. The received signal value and the determined transmission output are reflected in the reception average and the transmission average of the client file 72.

Upon receiving the transmission from the terminal 20X, the server 10B obtains the request value in the same manner as in the terminal 20X, stores the request value in the server file 73, and refers to the server default file using the received signal value. The transmission output is determined by the
X transmits a reception confirmation ACK.

On the other hand, if the server 10B cannot receive the transmission from the terminal 20X, no reception confirmation ACK is returned to the terminal 20X. Therefore, when the terminal 20X cannot receive the acknowledgment ACK within a predetermined period, the terminal 20X sets the transmission output to a value larger than the request value and transmits again with the transmission output as described above. This transmission output is also reflected in the client file 72.
In the server 10B, the data is similarly reflected in the server file 73. The above processing is performed in the terminal 20X and the server 10B for each packet.

When the communication job is performed and the communication job is completed and the communication job is performed again, the terminal 20X waits for the reception of the release signal from the server 10B. When the terminal 20X receives the release signal, the transmission output control circuit 5 compares the received signal value of the release signal obtained from the RSSI signal with the request value of the client file 72. The transmission output control circuit 5 sets the request value as the transmission output when the two are equal, and changes the transmission output to a larger value as described above when the received signal value is smaller than the request value.

As described above, until the normal communication with the server 10B is performed (for example, the reception confirmation A
Instead of repeating the transmission output update (until the CK is returned), the terminal 20X may notify the server 10B of the occurrence of interference.

For example, at the terminal 20X, which is a client, the RSSI signal becomes large due to the reception of radio waves (interfering waves) from the other terminal 20Y during the reception of data from the server 10B, and the reception of data from the server 10B. Becomes impossible because the correlation output cannot be obtained, the packet being received is discarded.

Thereafter, the RSSI signal returns to a normal value,
In addition, when the correlation output is obtained (when the interference wave disappears), the terminal 20X notifies the server 10B of the occurrence of the interference. The server 10B that has received this terminal 20
The priority of communication with X is increased. Thereby, the efficiency of communication between the server 10B and the terminal 20X can be improved, and as a result, the communication efficiency of the entire wireless LAN can be improved.

When the occurrence of the interference is further notified thereafter, the server 10B further raises the priority of the communication with the terminal 20X. As a result, communication between the server 10B and the terminal 20X can be secured, and the wireless LA
The communication efficiency of the entire N can be improved.

In addition to simply notifying the occurrence of interference, the reception level of the interference wave is recorded in the server file 73 of the server 10B as shown in FIG. May be determined.

For example, in addition to the MF3, the server 10B is provided with a correlator that has a similar function and outputs a correlation output signal of the (first) PN pattern (ID code) used by the other server 10C. Provide. The transmission output control circuit 5
RSS at the time when the correlation output signal is output from this correlator
The reception signal value obtained from the I signal is recorded in the server file 73 as the reception level of the interference wave 1. Similarly, the (second) PN pattern of the server 10A is recorded in the server file 73 as the reception level of the interference wave 2.

When the server 10B receives the signal of the PN pattern used by the server 10C after receiving the notification of the occurrence of the interference from the terminal 20X which is the client 2, the server 10B refers to the server file 73, and Reception level of pattern signal and server file 73
With the reception level of the interfering wave 1 of FIG. When the reception level of the PN pattern is equal to (or higher than) the reception level of the interfering wave 1, the server 10B
Is determined to be affected by the interfering wave 1, and the priority of communication with the terminal 20X is increased.
Thereby, the efficiency of communication between the server 10B and the terminal 20X can be improved, and as a result, the communication efficiency of the entire wireless LAN can be improved.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to these embodiments. That is, the transmission control means 40 may not be provided in each terminal 20 but may be provided integrally in a plurality of adjacent wireless LANs, and the transmission control means 40 may determine the communication timing instead of the transmission output. it can.

FIG. 8 shows another embodiment of the present invention, in which only one communication state monitoring and control device 70 as the transmission control means 40 is integrally provided in a plurality of adjacent wireless LANs. This embodiment is applied to a wireless LAN of the type shown in FIG.

The communication state monitoring and control device 70 monitors the communication state of each of the plurality of wireless adapters (repeaters) 60 connected by wire, and appropriately controls them. The communication state monitoring controller 70 transmits an instruction signal such as communication timing and communication data to the wireless adapter 60 and
0 transmits the communication status and the communication data to the communication status monitoring control device 70. These are wired communications. The communication status monitoring control device 70 is connected to the network server 80 of the main LAN 50 by wire. Therefore, the wireless adapter 6
0 is the main LAN 50 via the communication state monitoring and controlling device 70.
Is connected by wire. By providing the communication state monitoring and control device 70, communication efficiency can be improved.

Upon obtaining a communication permission from the communication state monitoring and controlling device 70, the wireless adapter A0 sets the terminal T0 corresponding to the wireless adapter A0.
It is assumed that communication is performed with (20). In this state, the communication state monitoring and control device 70
Even if a communication request with the terminal T1 is received from the wireless adapter A1 of 0, the communication is made to wait without giving permission to the wireless adapter A1. Then, as soon as the communication between the wireless adapter A0 and the terminal T0 ends, the communication state monitoring and control device 70 gives a communication permission to the wireless adapter A1. Thus, it is possible to prevent the terminals T0 and T1 from interfering with each other, and to start the communication immediately after the termination of the communication of the terminal T0.

In this case, the transmission output of the terminal T0 is changed to a level which does not hinder the communication with the wireless adapter A0 by referring to the client default file 71, for example, in accordance with the instruction of the communication state monitoring controller 70. It may be as small as. Thereby, the wireless adapter A0
The communication between the wireless adapter A1 and the terminal T1 may be permitted at the same time as the communication between the wireless adapter A1 and the terminal T0.

Further, in this case, the communication between the wireless adapter A0 and the terminal T0 and the communication between the wireless adapter A0 and the terminal T0 are performed only in a range in which the communication with the wireless adapters A0 and A1 overlaps with each other in accordance with an instruction from the communication state monitoring controller 70. Communication between A1 and the terminal T1 may be performed by time division.

9 to 11 show another embodiment of the present invention, in which a repeater (network server) 90 as the transmission control means 40 is integrated with a plurality of adjacent wireless LANs.
The embodiment provided with only one is shown. This embodiment is illustrated in FIG.
This is applied to the wireless LAN of the type shown in FIG.

As shown in FIG. 9, the repeater 90 appropriately communicates with each of the servers 10 (A to F) connected wirelessly in the same manner as between the server (base station) 10 and the terminal 20. To control. The repeater 90 transmits an instruction signal such as communication timing and communication data to the server 10, and the server 10 transmits communication data to the repeater 90.
These are wireless communications. The repeater 90 is the main LAN 50
Is connected to a gateway (GW) 100 by wire. By providing the repeater 90, communication efficiency can be improved.

As shown in FIG. 9, the connected server 10
Is M = 6, and the maximum number of adjacent areas is N = 4.
(For servers C and D). In this case, the repeater 90 uses the value of N, regardless of the value of M, as shown in FIG.
As shown in (1), each server 10 is caused to perform time division multiplex communication. In this case, the communication section is divided into (N + 1). That is, the maximum number N of adjacent areas and the other number (1
).

In FIG. 10, area A is a cell 30 corresponding to server A, "、" indicates an area in which communication is being performed, and "x" indicates an area which is obstructed by the communication (communication is being performed). Area adjacent to the area)
“△” indicates an area that is not disturbed by the communication (an area that is not adjacent to the communication area). For example, when area A (server A) is communicating, adjacent areas B, C and D (servers B, C and D) are disturbed by the communication, and areas E and F (server B,
C and D) are not disturbed by the communication. Therefore,
In this case, the relay device 90 does not perform (prohibit) communication with the areas B, C, and D (servers B, C, and D),
Communication is performed with areas E and F (servers E and F).

For this purpose, the repeater 90 sends a synchronization control signal to each of the servers A to F. The synchronization control signal is, for example, a high-level signal when communication is permitted, and is, for example, a low-level signal when communication is not permitted. In the above case, since a high-level synchronization control signal is transmitted to the server A, a low-level synchronization control signal is transmitted to the servers B, C, and D, and the server E
And F, a high-level synchronization control signal is transmitted.

Note that, without providing the repeater 90, FIG.
As shown in FIG. 1, each of the servers A to F may perform time division multiplex communication asynchronously. In this case, the number of time divisions is 2 × (N + 1).

In FIG. 11, “〇” indicates a time slot in which communication is being performed, and “×” indicates a time slot in which communication is prohibited. For example, after the server C in the area A performs communication in a certain time slot, the communication is prohibited in a time slot immediately thereafter. This makes it possible to eliminate the need for the repeater 90, while making it possible to extremely reduce the probability that communications in adjacent areas will interfere with each other due to the presence of a time slot for which communication is prohibited. The position of the time slot for which communication is prohibited can be changed to an arbitrary position, and the number may be two or more.

[0063]

As described above, according to the present invention,
In a wireless LAN, by providing transmission control means, each of the terminals can select an optimal transmission output or communication timing for its communication environment, so that terminals corresponding to different servers or wireless adapters interfere with each other. It is possible to solve the problem of distance and prevent the communication efficiency in the wireless LAN from being reduced.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is an explanatory diagram of a wireless LAN.

FIG. 3 is an explanatory view of an embodiment.

FIG. 4 is an explanatory diagram of a file.

FIG. 5 is an explanatory diagram of a file.

FIG. 6 is an explanatory diagram of a file.

FIG. 7 is an explanatory diagram of a file.

FIG. 8 is an explanatory view of another embodiment.

FIG. 9 is an explanatory view of another embodiment.

FIG. 10 is an explanatory diagram of time division.

FIG. 11 is an explanatory view of another embodiment.

FIG. 12 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 Reference Signs List 1 down converter 2 AGC (automatic gain adjuster) 3 MF (matched filter) 4 despreading circuit 5 transmission output control circuit 6 demodulation / PN control circuit 7 file 8 signal transmission means 9 changeover switch 10 server 20 terminal 30 cell 40 transmission control means

Claims (5)

[Claims] A plurality of servers, and a plurality of terminals provided corresponding to each of the plurality of servers, wherein the plurality of terminals are provided in a range where radio waves output from the corresponding servers reach and the corresponding servers. In a wireless LAN including a plurality of terminals that perform wireless transmission in, each of the terminals includes a transmission control unit that determines a transmission output based on an RSSI signal and a correlation signal, and each of the terminals includes its own A wireless LAN, wherein transmission is performed to the corresponding server with the transmission output determined by the transmission control means. 2. The transmission control means stores a result of transmission to the corresponding server in a predetermined file, and when transmitting to the corresponding server next time, an RSS
The method according to claim 1, wherein the presence or absence of a change in the communication environment is checked based on the I signal and the correlation signal, and if the communication environment has not changed, the transmission is performed based on a result stored in the file. The described wireless LAN. 3. A plurality of servers, and a plurality of terminals provided corresponding to each of the plurality of servers, wherein the plurality of terminals are provided within a range where radio waves output from the corresponding servers reach and the corresponding servers. In a wireless LAN comprising a plurality of terminals that perform wireless transmission by: a communication state monitoring and control device that is connected to each of the servers by wire and monitors and controls the state of communication in each of the servers; When the monitoring control device receives a request for communication from a server adjacent to the server performing communication, the monitoring control device causes the communication to wait without granting communication permission to the adjacent server, and causes the server performing the communication to After the communication ends,
A wireless LAN, which gives permission for communication to the adjacent server. 4. A plurality of servers, and a plurality of terminals provided corresponding to each of the plurality of servers, wherein the plurality of terminals are provided within a range where radio waves output from the corresponding servers reach and the corresponding servers. In a wireless LAN including a plurality of terminals that perform wireless transmission in a wireless LAN, a relay that is wirelessly connected to each of the servers and controls a state of communication in each of the servers is provided, and the relay performs communication. Communication is not performed with a server adjacent to the server that is performing communication, and communication is performed with a server that is not adjacent to the server that is performing communication, whereby time-division multiplex communication in which each of the servers is synchronized A wireless LAN. 5. A plurality of servers, and a plurality of terminals provided corresponding to each of the plurality of servers, wherein the plurality of terminals are provided in a range where radio waves output from the corresponding servers reach and the corresponding servers. In a wireless LAN composed of a plurality of terminals that perform wireless transmission, each of the servers performs asynchronous time-division multiplex communication by prohibiting communication in a time slot immediately after the time slot in which communication was performed. A wireless LAN, characterized in that: