JP3359765B2 - Wireless LAN system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a wireless LAN (Local
Area Network) system.

[0002]

2. Description of the Related Art A method for realizing a computer network using wireless communication can be roughly classified into two types: a centralized management system having a control station and a distributed management system having no control station. The former is a method in which the control station performs access control to avoid collision, and the latter is a method in which each station in the network detects and controls collision. Further, as a hybrid system, a method of performing management by a centralized system for a control system and a distributed system for a data system is also known. As for the channels used at that time, there are known control channels and a plurality of channels for data transfer.

[0003]

As described above, a wireless network system using a plurality of data channels has been proposed. However, this system cannot communicate with a terminal that is already communicating. In such a case, the connection is failed because the other party is busy, and a reconnection is generally attempted using a higher-level protocol (or application) on the terminal side. However, as the frequency of the wireless network increases, the bandwidth also increases, and the data transfer speed has dramatically increased. In such a system, the processing speed is shorter if a plurality of connection requests issued simultaneously to a certain station are processed in the control station as much as possible. It is also necessary to give priority to data communication such as voice data that has a time constraint, and return a connection failure to the terminal if connection cannot be made within the required time.

In a wired network, a device called a switching hub is provided in order to improve the throughput of a contention-based bus (shared) network system. This is a device having a port connected to each terminal and a high-speed switching function, and can connect between the ports in response to a connection request from the terminal. In a wired network, even if the number of terminals increases, the number of switching circuits and ports can be increased. However, in the case of wireless communication, the usable band is limited, and simply allocating one channel to each terminal immediately uses up the band. For example, if a 100 MHz band is divided by 10 MHz per channel, the maximum is 10
Only channels can be obtained, and ten terminals cannot be connected.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to allow a plurality of connection requests to the same station, enable data communication with time restrictions, and use radio waves which are limited resources. It is an object of the present invention to provide a highly flexible network system capable of dynamically changing the communication speed by increasing the number of terminals accommodated by effectively using the communication system.

[0006]

Means for Solving the Problems The present invention, in order to solve the above problem, a computer network using a wireless consisting (1) control station and a plurality of stations other than the control station (terminal) The control station divides a frequency band used for communication for performing access control into a plurality of channel groups,
The plurality of terminals are divided into several groups, and each terminal belongs to any of the channel groups, and each terminal transmits and receives channels for the channels of its own group , and reserve channels that do not belong to any group. And (2) using the reserved channel when performing data communication with a high degree of urgency, or (3) when the communication data amount of a certain terminal is large, the control station transmits a plurality of channels to the terminal. Or (4) when the communication data amount of a certain terminal station is large, the control station increases the band by allocating the reserved channel to the terminal station. .

[0007]

[Action] According to dynamically changing network usage
Flexible network system with variable number of available channels
System.

[0008]

EXAMPLE 1 FIG. 1 is a diagram showing a configuration of a network system to which the present invention is applied, in FIG, 10 is a control station, 11 exchange function block 12 is the control unit, 20 ₁ ～20N terminal (station other than the control station), RX ₁ ~RX _n data channel receiver and demodulator, TX ₁ ~TX _n is the transmission unit and the modulation of the data channel, TRX ₁ ~TRX _n transmission and reception of the data channel, TRX _c is a transmission / reception unit of the control channel. FIG. 2 shows an example of a queue of communication request blocks. The band allocated for communication is divided into a number of channels, and one band is allocated to each wireless terminal for data communication. One channel is for control and can be accessed by all stations. The control station has access to all data and control channels. The control station has the function of connecting data coming from all input channels to any output channel.

When a certain wireless terminal station A communicates with another station (terminal) B, it issues a communication request to the control station using a control channel. The communication request includes the address of the own station and the address of the communication request destination. The control station receiving this sets the switching function in the control station so as to connect the channel allocated to the terminal A to the channel allocated to the terminal B. Further, the control station returns a response to the communication request source using the control channel. As a result, the requesting source knows that the connection has been established, and performs communication using the data channel. When the communication is completed, the communication completion is notified to the control station using the control channel. As a result, the control station sets the exchange function so as to release the connection between the channel allocated to terminal A and the channel allocated to terminal B.

[0010] If terminal B is communicating with another station,
The control station creates a communication request block and inserts it at the end of the communication queue (FIG. 2). The communication request block has a data structure in which addresses of the own station and the other party are described. When the communication completion is transmitted from the terminal B or a station communicating with the terminal B to the control station, the control station extracts a communication request block from the head of the communication queue and establishes connection with the communication request source. Furthermore,
Thereafter, a response signal is returned using the control channel to notify the request source that the connection has been established.

According to Example 2 before clean 1, it has come to handle multiple connection requests the control station. In this example 2 , a priority field is provided in the communication request block so that communication data having a higher priority can be processed. FIG. 3 shows a queue of the above-mentioned communication request block. In FIG. 3, P1 ≧ P2 ≧
Pn. When a station issues a communication request, a priority p is set in addition to the addresses of the own station and the partner station. If the other party is communicating, the queue is checked from the beginning and inserted immediately before the first block having a priority lower than p.

[0012] In Example 3 Example of this 3, the control station comprises a timer to the minimum unit of a sufficiently short time, an interrupt is applied to every unit time. When an interrupt is issued from the timer, the processing that has been performed up to that point is interrupted and the control program specified in advance is executed. When the execution of the interrupt processing is completed, the processing returns to the original processing. In this system, a connection request time field is further added to the communication request block. FIG. 4 shows a queue of the above-described communication request block. When the communication request destination is already communicating and the communication request source requests connection completion within time m, the connection request time is reduced. Create a communication request block in which m is written in the field and connect to the queue. Each time an interrupt occurs, the request block in the communication queue is checked to see if the connection request time has passed. If the current time has passed the required time, the block is removed, and a negative response is sent to the communication request source indicating that the connection has failed. There are several methods for checking the expiration of time. For example, when creating a communication request block, a method of writing the current time + m and comparing the current time with the current time every time an interrupt occurs, or m as (connection request time / Interval of the timer interrupt), and subtracting 1 from the connection request time field of every request block every time an interrupt occurs, and expiring a value of 0 when the interrupt is completed.

Example 4 In general, the control channel has a smaller bandwidth because the amount of information to be transmitted is smaller than that of the data transfer channel. Therefore, it is conceivable to set the frequency band of the control channel to another band having a narrower band in order to increase the band of the data transfer channel. For example, a band having a wide band of 60 GHz is used for data transfer, and the control channel is set to 2.4 GHz.

Example 5 According to Example 1, a wireless network system with high throughput could be provided. However, in this method, the transmission and reception channels allocated to each terminal are fixed,
The number of terminals obtained by dividing the entire band by the band per channel, that is, (total band / band of one channel) terminals, cannot be connected. However, it is rare that all terminals actually communicate at the same time. Therefore, all terminals are provided with transmission / reception units for all channels. Figure 5 is a diagram for explaining an example 5, in the figure, the 10 control station, 20 21 _to
0n is a terminal station. When performing communication, the terminal station first
A communication request is issued to the control station 10 using a control channel. If the control station having received this there is <br/> OriKatsu vacant channel communication destination terminal station is have empty, inform the idle channel in both terminal stations, to perform communication by establishing a connection. When the communication is completed, the control station is notified of the completion of the communication. As a result, the control station recovers the used channel and prepares for the next request. Also in this case, as in the first embodiment, a flexible network can be constructed by giving a priority to a communication request and connecting a communication request having a higher priority to the front of the queue.

[0015] According to the example 6 before clean 5, effective use of limited frequency band,
A network system for communicating between a large number of terminals could be provided. However , according to the method of Example 5, since all terminals have transmission / reception units for all channels, the circuit configuration and control become complicated and the cost increases. Therefore,
The configuration is as follows. First, all channels included in all frequency bands are divided into a plurality of groups. Here, the number of all channels is N, the number of groups to be divided is g, and the number of channels included in each group is n. Where n ≧ 1, N
≧ g ≧ 1. When a terminal requests a use channel from the control station, the control station selects and allocates a free channel group from the channel groups to which the terminal belongs. When communication is completed, the used channel is released.

[0016] Example 1 FIG. 6 is a diagram for explaining a first embodiment of the present invention, in which the 10 control station, the 30 ₁ to 30 ₄ with a channel group, 6, the terminal 1-3 There belong to channel groups 30 _1, the channels used in channel group 30 ₁ C
H ₁ and CH ₂ . In this group, only two terminals can communicate at the same time because there are only two channels for three terminals. Also, channels used in channel group 30 ₂ is CH _3, CH _4, the number of terminals that can communicate simultaneously in the channel group 30 ₂ is also two. On the other hand, channel group 30 ₃ two terminals 8,9
, Two channels CH ₅ and CH ₆ are allocated, so that both can always communicate with each other. Such a channel group is effective in a case where terminals in it frequently communicate, such as a server. Further, as shown in the channel group 30 _4, if put into one channel group attracting small communication frequency terminals,
Fewer channels need to be allocated.

By constructing as described above, a flexible network can be configured according to the network usage status of the terminal. However, network usage changes dynamically. In terms of the example above, the terminal 10 and 11 belonging to the channel group 30 _4, in some cases at the same time to carry out the urgency high data communication. This group 3
0 ₄ either because there is only allocated one channel CH ₇ to will be waiting. In the present invention,
To avoid this, leave reserve a channel that does not belong to anywhere groups, the assigned channel number or channel group to temporarily allocate when it becomes necessary.

Embodiment 2 Although the amount of communication data does not increase in an application such as remote login to another station, it is desirable that the amount of data be large when image data is transferred, and that high-speed network communication be possible. Therefore, a field of a necessary band (transfer speed) is provided in the communication request, and this value is set to a large value when transferring a large amount of data. Upon receiving this, the control station monitors the state of the vacant channel, and if it is vacant, allocates a plurality of channels for transfer.

Embodiment 3 This embodiment has a function of dynamically changing the band by using the reserve channel described in Embodiment 1 when the communication data amount is large. When the communication data amount of the terminal station is large, the control station allocates the reserved channel described in the first embodiment to the terminal to increase the bandwidth.

[0020]

As is apparent from the above description, the present invention has the following effects. Circuitry configuration and control can construct a simple and low-cost network, further, it is possible to construct the flexible network system according to the network usage of each terminal. Further
The number available channels is changed depending on the network usage status dynamically changing, it is possible to provide a flexible network system. Further, not only the number of usable channels but also the bandwidth of one communication can be dynamically changed, and a more flexible network system can be provided.

[Brief description of the drawings]

1 is a block diagram for explaining the onset Ming network system.

2 is a diagram for explaining an example of a wait queue.

3 is a diagram for explaining another example of the wait queue.

4 is a diagram for explaining another example of the wait queue.

[Figure 5] system is a diagram for explaining the details of the station other than your office.

FIG. 6 is a diagram illustrating a channel group according to the present invention.

[Explanation of symbols]

10 ... control station, 20 ₁ ~20n ... terminal, 30 ₁ to 30 ₄ ...
Channel group, RX ₁ to Rx _n ... data channel receiver and demodulator, the transmission unit and the modulation of the TX ₁ ~TX _n ... data channel, the transceiver of TRX ₁ ~TRX _n ... data channel, the TRX _c ... Control Channel Transmitter / receiver.

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 12/28 H04Q 7/38 H04B 7/208 H04M 3/48

Claims (4)

(57) [Claims] 1. A wireless computer network comprising a control station and a plurality of stations (terminals) other than the control station, wherein the control station assigns a frequency band used for communication for performing access control to a plurality of channel groups. The plurality of terminals are divided into several groups, and each terminal belongs to any of the channel groups, and each terminal transmits and receives channels for the channels of the group to which the terminal belongs.
And has a reserved channel that does not belong to any group
A wireless LAN system. 2. The reserved channel is used when performing data communication with a high degree of urgency.
2. The wireless LAN system according to 1 . Wherein there is large amount of communication data terminal, the control station wireless LAN according to claim 1, wherein increasing the bandwidth by assigning a plurality of channels to the terminal
system. 4. When a communication data amount of a terminal station is large,
Control station wireless LAN system according to claim 1, wherein that said increasing the bandwidth by allocating the reserved channel to the terminal.