JP2003174457A - Wireless lan system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless LAN system in which multi-path fading caused by a plurality of communication paths can be suppressed and the effective band rate is not decelerated. <P>SOLUTION: The wireless LAN system has a waveguide 1a, a wireless LAN base unit 2a connected to this waveguide 1a and wireless LAN handsets 3a to 3c. The waveguide 1a has a plurality of branch circuits 5a to 5c, and antennas 6a to 6c for transmitting/receiving electromagnetic waves are connected to these branch circuits 5a to 5c. Data communications are performed between the wireless LAN base unit and the wireless LAN handsets by a packet system. In such a system, a network address of a packet sending destination of the specific wireless LAN handset 3a and the specific branch circuit 5a to be used for the communications with the wireless LAN handset 3a are correlated beforehand, and corresponding to the network address of the packet to be communicated, the specific branch circuit 5a corresponding to this address is selectively opened. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless LAN (local area network) system that forms a wireless communication network in a certain area such as indoors.

[0002]

2. Description of the Related Art In recent years, with the development of an advanced information-oriented society, inside offices such as buildings, premises such as factories and warehouses, indoors such as general houses and offices, and other than indoors, Wireless LAN in certain areas such as arcades of shopping streets, station platforms, airport terminals, large temporary structures such as tents, and event venues
The use of systems (local wireless networks) is expanding.

In this wireless LAN system, the wireless LA
N Communication is performed between the base unit and a large number of wireless LAN handset units located in the area using electromagnetic waves in a wide frequency band. For example, the 1.9 GHz and 2.4 GHz quasi-microwave bands are used for personal handyphone systems (PHS) and medium-speed wireless LANs, and the 19 GHz quasi-millimeter wave band and 60 GHz band millimeter-wave bands are used for high-speed wireless LANs. Wave bands are assigned to each.

Taking the case of an indoor wireless LAN system as an example, indoors usually have many electromagnetic wave obstacles such as desks, shelves, partitions and office equipment between the wireless LAN master unit and slave units. Exists. For this reason, the electric field strength of the electromagnetic wave (signal) arriving around the obstacle is reduced, and the S / N (SN ratio) necessary for demodulating the transmitted data cannot be obtained sufficiently. As a result, the error rate of data increases, retransmission is performed, and the effective communication speed decreases.

Even if there are no obstacles to electromagnetic waves and the visibility of the interior is good, the transmitted data is still affected by the reflected waves of electromagnetic waves from the wall surface, ceiling surface, floor surface and the furniture and office equipment. Needed to demodulate
There is also a problem that the S / N (SN ratio) cannot be obtained sufficiently and the communication speed becomes slow. Then, these problems may occur in the wireless LAN system in the certain area other than indoors as well.

Regarding this problem, at a ceiling height of 3 m, 18 m ×
In a room with a large number of desks and chairs arranged in a size of 6 m, the present inventors actually measured, using the quasi-microwave band of 2.4 GHz band, has a high-speed data communication performance of up to 11 Mbps,
It was confirmed that when a commercially available wireless LAN device was used, the communication speed varied greatly depending on the location in the room, and the communication rate could be 1/10 of the maximum value depending on the location.

Regarding the influence of reflected electromagnetic waves (multipath fading) when forming a wireless communication network, the applicants have previously proposed that the multipath fading be suppressed in Japanese Patent Application No. 2001-171265. The wireless LAN system and wireless LA have been improved so that the effective communication speed does not decrease.
A waveguide device for N system is proposed.

In this Japanese Patent Application No. 2001-171265, a waveguide provided along the upper side in an area forming a wireless communication network,
It has a wireless LAN master unit connected to this waveguide and a wireless LAN slave unit arranged in the area, and the waveguide has a plurality of branch circuits, and this branch circuit goes into the area. Radio connected with an antenna for transmitting and receiving electromagnetic waves having directivity
The main idea is to use a LAN system.

With this configuration, even if an electromagnetic wave obstacle is present, it does not become an obstacle for electromagnetic wave communication between the master unit and the slave unit of the wireless LAN. Also,
Even if there is a reflected wave of an electromagnetic wave, its influence is reduced.

Further, in Japanese Patent Application No. 2001-171265, the effect of suppressing multipath fading is enhanced by giving directivity to the electromagnetic wave transmitting / receiving antenna provided in the branch circuit or the wireless LAN slave unit.

[0011]

With this technique,
It is possible to surely suppress multipath fading due to obstacles in electromagnetic wave communication. However, in the case of a wireless LAN system in which the waveguide has multiple branch circuits or when there are multiple wireless LAN base units, the electromagnetic waves transmitted from the wireless LAN base unit to a specific slave unit are output from multiple branch circuits. Each of the master station antennas reaches the slave unit. Also, multiple wireless
A plurality of electromagnetic waves transmitted from the LAN master unit reach the slave unit through the master station antenna from the branch circuit corresponding to the specific slave unit.

For this reason, a plurality of communication paths from the wireless LAN base unit to a specific handset exist, and the problem of multipath fading due to itself is likely to occur.

When the frequency of the electromagnetic wave used for communication is high, this problem has a small effect, but especially when the frequency of the electromagnetic wave used for communication is low, it is affected by the multipath fading due to the plurality of communication paths. It may be easy and difficult to obtain high directivity.

The present invention has been made in order to improve the above situation, and an object thereof is to suppress multipath fading due to the plurality of communication paths even when the frequency of an electromagnetic wave used for communication is low. , Aims to provide a wireless LAN system that does not reduce the effective communication speed.

[0015]

In order to achieve the above object, the gist of claim 1 of the present invention is to provide a waveguide provided along an area forming a wireless communication network and to connect to the waveguide. Wireless LAN base unit and wireless LA installed in the area
N slave unit, the waveguide has a plurality of branch circuits,
A wireless LAN system in which the branch circuits are each connected to an electromagnetic wave transmitting / receiving antenna having directivity toward the area, and perform data communication between the wireless LAN master unit and the wireless LAN slave unit by a packet method. And a specific wireless LAN
Packet transmission destination network address of the handset and the wireless
The specific branch circuit used for communication with the LAN cordless handset is associated in advance, and the specific branch circuit associated with this address is selectively opened according to the network address of the packet to be communicated. That is what I did.

The packet system in the wireless LAN system of the present invention means, as shown in FIG.
Data X is divided into fixed amount into packets (parcel) Y1 and transmitted while being relayed to the destination (wireless LAN slave or wireless LAN master) with several exchanges (antennas for electromagnetic wave transmission / reception). Is. Packet (parcel) Y1
In addition to the main unit data X1, the destination and sender (wireless LA
N The address (address of the slave or wireless LAN base unit) or the header (shipping tag) Z1 that displays the packet order is attached. Therefore, in packet-based data communication, it is not necessary to prepare a dedicated communication line for each destination, and a single communication line (waveguide) can be used to send packets to various destinations (multiple wireless LAN slaves). There is a feature that can communicate.

In the wireless LAN system of the present invention, on the premise of communication by such a packet system, the branch circuit is made to wait for the role of a switch, and for example, it corresponds to a specific wireless LAN slave device of a packet destination to be communicated. Only specific branch circuits are selected and opened. Therefore, when forming a wireless communication network, the electromagnetic wave transmitted from the wireless LAN master device can reach the slave device only through the specific master station antenna selected from within the waveguide. Therefore,
Wireless LAN It is possible to make the communication path from the base unit to the handset unique, suppress or eliminate the influence of electromagnetic waves (multipath fading) due to the electromagnetic waves from multiple other branch circuits, and communicate with high S / N. be able to.

Further, according to claim 2 of the present invention, the wireless
It has a list of wireless LAN slaves with which the LAN master communicates, and polls the wireless LAN slaves in sequence according to this list,
It is preferable to grasp the timing of communication between the master unit and each slave unit, and select the specific branch circuit to be opened during the period during communication between the master unit and the specific slave unit according to this grasped timing.

Further, according to the present invention, the device configuration of the waveguide may be a waveguide as claimed in claim 3 or a waveguide which is a microstrip line as claimed in claim 5. The preferred mode of the branch circuit is different.

That is, when the waveguide is a waveguide, as an embodiment of the branch circuit, the branch circuit includes a rod-shaped coupling conductor and one end of the coupling conductor. A radiation plate attached to the waveguide, the coupling conductor is inserted through an insulating material into a hole provided in the waveguide, and the radiation plate is directed inside the section. It is preferable that a patch antenna is formed on the inner surface of the area of the plate, and a branch switch that opens and closes the connection between the patch antenna and the radiation plate connecting portion of the coupling conductor according to a control signal is provided.

On the other hand, the waveguide is a microstrip line, and the microstrip line itself has a ground layer made of a conductor material, a signal line made of a dielectric layer made of a dielectric material and a conductor material. When a patch antenna having a structure in which a dielectric plate made of a dielectric material and a patch made of a conductor material are sequentially laminated is electrically coupled to the signal line, As an embodiment of the branch circuit, it is preferable that a branch switch that opens and closes the connection between the signal line and the patch antenna according to a control signal is provided.

When the patch antenna is electrically coupled to the signal line through a coupling portion as in claim 7, as an embodiment of the branch circuit, the branch switch includes the coupling switch. It is preferable that it is provided so as to open and close the connection between the section and the patch antenna.

Further, in a case where the patch antenna is electrically coupled to the signal line via a coupling portion,
It is also preferable that the branch switch is inserted in the signal line and the patch antenna is electrically coupled to the branch switch, as shown in FIG.

Since the present invention has the configuration and effects as described above, it is suitable for being applied to an indoor wireless LAN system in which the area is indoors as in the gist of claim 9, but it is further suitable for an arcade. , Platform, terminal,
Alternatively, it may of course be applied to a certain area such as a large temporary structure or a temporary hall, such as inside a structure or outdoors.

Further, in the present invention, in order to suppress multipath fading due to an obstacle of electromagnetic wave communication in the area, the wireless LAN master unit and the slave unit are arranged along the upper part of the area forming the wireless communication network. It is preferable that the connection is made via a waveguide provided as above. More specifically, the present invention claims
As in the tenth point, in the case of indoors, it is preferable to connect via a waveguide provided along the ceiling of a building or the like.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. As a first embodiment, a case where the waveguide is a waveguide as in claim 3 will be described below. First,
An example of a device (hardware) configuration as a premise of the wireless LAN system of the present invention will be described with reference to FIGS. FIGS. 3 and 4 show an example in which the waveguide type wireless LAN system of the present invention is applied indoors such as an office room. Here, Fig. 3 is a perspective view of the office building (room), and Fig. 4 is a sectional view taken along the line AA of Fig. 3.

3 and 4, the wireless LAN system of the present invention is located in the upper part of the area, along the ceiling 11 of the building 10 (having doors 16a and 16b), behind the ceiling or on the indoor side of the ceiling. Waveguides 1a and 1b provided on the surface with two gaps
And the wireless LA connected to the ends of the waveguides 1a and 1b, respectively.
N base unit 2a, 2b and multiple indoor units (two units in the figure)
Basically, it has wireless LAN slaves 3a and 3b (connected to OA devices 8a and 8b, respectively).

In the middle of the waveguides 1a and 1b, a branch switch module that can be opened (opened / closed) toward the inside (downward of the area) is formed, and an ON / OFF signal is given to electrically switch the signal. A plurality of branch circuits 5a to 5c and 5d to 5f each including a switch device capable of switching a path are provided. The branch circuits 5a to 5c (also branch circuits 5d to 5f) are connected to electromagnetic wave transmitting / receiving (master station) antennas 6a to 6c having directivity toward the area.

At the ends of the waveguides 1a and 1b (ends on the side opposite to the wireless LAN base unit), the electromagnetic waves passing (going back and forth) in the waveguides interfere with each other so that they are not disturbed. It has non-reflecting end portions (terminations) 4a and 4b, respectively, which are filled with or composed of a known material that does not reflect electromagnetic waves, such as resin or inorganic material.

Further, coaxial-waveguide converters 12a and 12b are respectively connected to the ends of the waveguides 1a and 1b on the base units 2a and 2b side,
From there, use the cables 15a and 15b to connect to the wireless LAN base units 2a and 2b.
It is connected to the connector terminal.

The master station antennas 6a, 6b, 6c are directed toward the lower indoor area (in the area), and the wireless LAN slave units 3a, 3b (for personal computers, etc.)
OA devices 8a and 8b) are connected to the slave antennas 7a and 7b, respectively, which have directivity, preferably high directivity, to enhance the sensitivity of transmission and reception of electromagnetic waves A and B, and to disturb electromagnetic waves. It is preferable to make it less likely to be affected by an obstacle, an electromagnetic wave reflected indoors, or the like.

With the above-mentioned basic configuration of the wireless LAN system of the present invention, via the waveguides 1a and 1b provided along the ceiling 11 (along the upper part in the area forming the wireless communication network),
Electromagnetic wave transmission / reception areas X1, X2, X3 between the master station antennas 6a, 6b, 6c and child device antennas 7a, 7b and electromagnetic wave transmission / reception areas Y1, Y2 of the electromagnetic wave transmission / reception antenna 7 of the child device to be covered Are formed, and electromagnetic waves A and B are transmitted and received.

Here, the basic configuration of the wireless LAN system shown in FIGS. 3 and 4 is a feature of the present invention.
Assuming packet communication, the packet destination network address of the specified wireless LAN slave unit and the wireless LAN
An example in which a mode for associating with a specific branch circuit used for communication with a child device is added will be described below with reference to FIGS.

As shown in FIG. 1, the branch circuits 5a to 5c used for communication with the wireless LAN slave unit are associated with the packet transmission destination network address of the specific wireless LAN slave unit.
The branch switch is modularized. This branch circuit must wait for the role of a switch, and a specific branch circuit corresponding to a specific wireless LAN slave unit must be able to selectively open and close. Therefore, as will be described later with reference to FIGS. 7, 8 and 9, the branch circuit is not a simple mechanical opening, but is made into the branch switch module, and electrically switches the signal path by giving an ON / OFF signal. It consists of a switching device that can be opened and closed indoors (below the area). As a result, for example, when ON, the signal is connected to the terminating resistor, and the waveguide and the master station antenna are not coupled. On the other hand, when it is OFF, the waveguide and the master station antenna are coupled.

An antenna controller 17 is connected to the wireless LAN base unit 2a. And this antenna control unit 17 is a waveguide
Signal lines 20 (20a, 20b, 20c) are connected to a plurality of branch circuits (branch switch modules) 5a-5c installed in 1a, respectively. Therefore, the antenna control unit 17 has a branch circuit.
It is possible to control 5a to 5c independently.
A backbone network 19 that communicates with other external wireless LAN systems and communication systems is connected to the wireless LAN base unit 2a.

The antenna control unit 17 has a wireless LAN slave unit in advance.
3a, 3b, 3c packet destination network address,
A correspondence table with the specific master station antennas 6a to 6c to be used for communication with the wireless LAN slave device is provided as a slave device (slave station) reference table 18. This slave station reference table 18 is a wireless LAN
Once the slaves 3a, 3b, 3c are installed, once registered in the table 18, it is not necessary to re-register unless the wireless LAN slaves 3a, 3b, 3c are moved.

Here, a specific wireless LA is transmitted from the wireless LAN base unit 2a.
When data is transmitted to the N slave unit, the packet destination network address of the specific slave unit is designated and sent to the antenna control unit 17 as a control signal 9. The antenna control unit 17, which has been sent the control signal 9, identifies the wireless LAN slave device from the network address, and identifies the specific master station antenna to be used when communicating with this specific wireless LAN slave device, in the reference table. Determine with reference to 18.

After that, the antenna control unit 17 sets only the branch circuit connected to the determined specific master station antenna to the signal line 20.
Via the signal line 20.
Set to OFF. As a result, the electromagnetic waves currently transmitted from the wireless LAN master device 2a reach the slave device only through the specific master station antenna selected from within the waveguide 1a. Therefore, the problem of multipath interference can be solved by uniquely determining the communication path from the wireless LAN master unit 2a to the slave unit.

From the wireless LAN base unit 2a to the antenna control unit 17,
When sending the packet destination network address of a specific slave unit as a control signal, if the amount of communication information and communication time information to that slave unit are also given as control signals, it corresponds to this amount of communication information and communication time. For a certain period of time, that is, an appropriate time that does not interfere with communication with other slave units, the master station antenna
(Branch circuit) ON, other master station antenna (Branch circuit)
Can be turned off.

The antenna control unit 17 is a wireless LAN base unit.
The above control is performed when transmitting data from 2a to a specific wireless LAN slave unit, but when there is no traffic or when the wireless LAN slave unit communicates with wireless LAN master unit 2a. In this case, it is preferable to control so that all connected branch circuits are kept in the ON state.

With the above configuration, in the case of a wireless LAN system in which the waveguide has a plurality of branch circuits,
Even if there are multiple LAN base units, multiple base station antennas are not coupled to the waveguide at the same time. For this reason, for example,
To the slave unit 3b of 1, data is transmitted from the wireless LAN master unit 2a only through the route A via the master station antenna 6b, and a multipath route such as B via the master station antenna 6a may occur. There is no.

Next, a case where the communication control method between the wireless LAN master unit and the slave unit is the polling method will be described below. The polling method is a method in which the child device always responds by a signal from the parent device, and is a method in which the child device does not spontaneously make a call. The master unit polls each connected slave unit one by one, and each slave unit can transmit only as a response to the polling from the master unit. Since the transmission timing of each slave unit is always known by the master unit, the master unit does not only need to know the transmission timing to the slave unit, but also the slave unit during the period when it expects a response from the slave unit. Turn on only the corresponding branch circuit
Can be Therefore, by limiting the communication path including the time of transmission from the slave unit to the master unit and limiting the master station antenna to be used, bidirectional multipath interference can be avoided.

A communication control system between the master unit and the slave unit of the polling method will be described with reference to FIG. In addition,
The element numbers in FIG. 2 correspond to the element numbers in FIG.
In FIG. 2, the master unit has a polling list in which slave units that connect (communicate) to the network are registered in advance. When the parent device 2a has data addressed to the child device 3a, the parent device 2a transmits the data addressed to the child device 3a following the polling message 21 for the child device 3a. By referring to the network address of the slave 3a added to the header of the polling message 21, the slave 3a recognizes that the polling is addressed to itself and receives the data.

At this time, when the child device 3a has data addressed to the parent device 2a or the backbone network above it, after completion of receiving the data addressed to itself, the polling response message 22 is followed by the data. To send.

On the other hand, the master unit 2a waits for the transmission data from the slave unit 3a for a fixed time-out period after the end of the data transmission to the slave unit 3a. If there is a response from the slave unit before the end of this timeout period, the polling response message 22 and the data following it are received. Since the polling response message 22 is added with the data length to be transmitted from the slave 3a to the master 2a, the master 2a can know the period during which the response from the slave 3a is maintained. Base unit 2a or above
During communication between the slave unit 3a and the slave unit 3a, the master unit 2a presents the network address of the slave unit 3a of the slave unit 3a to the antenna control unit 17 in FIG. Therefore, during the communication between the master unit 2a and the slave unit 3a, only the master station antenna 6a (branching circuit 5a) corresponding to the area where the slave unit 3a is arranged can be turned on.

When the master unit 2a finishes the reception from the slave unit 3a,
Similarly, the slave unit 3b is similarly polled. At this time, only the master station antenna 6b (branch circuit 5b) is selected.

The last slave unit 3c in the polling list
When the slave 3c has no data to be transmitted when the slave 3c is polled, the slave 3c does not respond to the polling. Therefore, the parent device 2a waits for the transmission data from the child device 3c for a fixed (maximum) time-out period, and then again proceeds to poll the child device 3a registered at the head of the polling list. Then, this procedure is repeated.

With the above configuration, in the case of a wireless LAN system in which the waveguide has a plurality of branch circuits,
Even if there are multiple LAN base units, the base unit knows the communication timing with each handset unit, so the optimum base station antenna for communicating with each handset unit is selected and the multi-source generated in the waveguide is selected. It enables communication without causing the problem of path interference.

FIG. 6 shows the test results of multipath interference according to the embodiment of FIG. Figure 6 shows the relative relationship in the X direction between the waveguide 1a and the office compartments, showing the office compartments 1 to 3 partitioned by the blindfold and the communication status in each compartment in a planar manner.
It is shown in 3 levels (○: IP can be acquired, △: IP can be acquired but responsiveness is poor, ×: IP cannot be acquired). In FIG. 6, reference numerals 6a to 6f denote master station antennas periodically arranged in the waveguide 1a, and only this portion is illustrated from the side.

Now, when communication is performed with all the master station antennas 6a to 6f (branch circuits) turned on without performing the packet system communication of the present invention, as shown in FIG. In the office sections 1-1 to 1-3 that are communicated through 6a, there are many places where the communication status is △ to ×.

On the other hand, when communication is performed by the packet system of the present invention and only the master station antenna 6a is turned on and the other master station antennas are turned off, the offices 1-1 to 1 Up to -3, all IP can be acquired. From this fact, the sections 1-1 to 1-3 of the office have a path for communication with the access point via the master station antenna 6a and a path for communication with the access point via the master station antenna 6b. It can be seen that, between the two, multipath interference is likely to occur. Further, it is understood that this multipath interference can be prevented by the packet communication according to the present invention.

Next, the embodiments of the individual elements of the apparatus (hardware) configuration of the wireless LAN system which is the premise of the present invention described in FIGS. 3 and 4 will be described in more detail.

First, the branch circuits 5a-5c and the master station antenna
Specific configuration examples of 6a to 6c are shown in FIGS. Figure 7
Is a sectional view of the branch circuit 5a, and Fig. 8 is the radiation plate 22 in Fig. 7.
Fig. 9 is a plan view showing the back surface of Fig. 9, and Fig. 9 is a circuit diagram of Fig. 8.

In FIG. 7, the branch circuit 5a is provided with a rod-shaped coupling conductor 21, a radiation plate 22 attached to one end of the coupling conductor 21, and a rear surface 22a of the radiation plate 22, which will be described later with reference to FIG. The branch switch 27a and so on.
The coupling conductor 21 is made of a conductive material, and the hole 1 _x provided in the waveguide 1a is provided with an insulating material made of a dielectric material.
It is inserted almost vertically through 24. The radiation plate 22 has a laminated structure in which a dielectric layer 25 made of a dielectric material is sandwiched between ground layers 23 made of a conductive material. Then, the radiation plate 22 is made substantially horizontal so as to be directed to the inside of the area, and the connection portion 28 of the coupling conductor 21 and the lower ground layer.
Connected at 23.

As shown in FIG. 8 showing the back surface 22a of the radiation plate 22,
On the back surface 22a of the radiation plate 22 (the surface of the ground layer 23 inside the area), a flat patch antenna 26 made of a conductive material is used.
And a branch switch 27a. Patch antenna
26 has an electrical coupling portion 26a with a branch switch 27a. A control signal line 20a, a radiation plate connection portion 28 of the coupling conductor 21, and a power supply line 29a are connected to the branch switch 27a. A terminating resistor 30a is connected to the non-selected side of the branch switch 27a and is connected to the ground layer 23 below the patch antenna 26.

As shown in FIG. 9 which is a circuit diagram (switch operation diagram) of FIG. 8, the branch switch 27a responds to a control signal from the antenna controller 17 via the control signal line 20. The connection between the patch antenna 26 and the coupling conductor radiation plate connecting portion 25 is opened and closed. As a result, for example, when the control signal from the antenna control unit 17 in FIG. 1 is in the ON state, the coupling conductor radiation plate connection unit is
25 and the patch antenna 26 are coupled to each other, and the electromagnetic wave from the waveguide 1a is radiated from the patch antenna 26 toward the specific handset. On the other hand, the control signal from the antenna controller 17 is OF
In the F state, the coupling conductor radiating plate connecting portion 25 and the terminating resistor 30a are connected, the waveguide 1a and the patch antenna 26 as the master station antenna are not coupled, and electromagnetic waves are not radiated.

In the branch circuit 5a shown in FIG. 7, the axial center of the coupling conductor 21 and the plane center of the radiation plate 22 are displaced from each other. In this way, by displacing the centers of each other, the high frequencies radiated from the patch antenna 26 to the inside of the area (indoor) are not evenly radiated, and have strong directivity (deflection) to the corresponding slave unit. Can have

Next, an example of arrangement of the wireless LAN base stations 2a and 2b will be described. In the examples of FIGS. 3 and 4, the wireless LAN base units 2a and 2b are arranged in the same room as the handset units 3a and 3b. However, in the present invention, since the wireless LAN master unit and the slave unit are connected via the waveguide provided along the ceiling (above the area) of the building, the wireless LAN master units 2a and 2b are connected. Placement indoors (in the area)
However, it is not always necessary to arrange it as described above, and it may be arranged outdoors or in another room (in the area) which is separated from or indoors of the slaves 3a and 3b.

Next, an arrangement example of the waveguide will be described. In the present invention, the waveguide itself such as the waveguide or the microstrip line does not necessarily have to be provided above the area like the ceiling 11. If it is suitable for forming the wireless communication network in the area, it may be provided, for example, on the side of the wall surface of the building 10 in the area.

Although two waveguides (waveguides) are provided in the examples of FIGS. 3 and 4, even when a plurality of different waveguides are used by providing a plurality of waveguides in this way, The channels do not interfere with each other and can be repeatedly used, which contributes to the improvement of the transmission rate.

The waveguide itself shown in FIGS. 3 and 4 is composed of a well-known conductive metal waveguide such as stainless steel, steel, copper, aluminum, etc. in view of suppression of electromagnetic wave transmission loss and construction efficiency. Is preferable. If the transmission loss of electromagnetic waves can be suppressed, wireless power can be effectively used.

The waveguide itself may be a microwave transmission line other than the waveguide, such as a microstrip line or a coaxial cable described later, as long as the gist of the present invention is not impaired. . The present invention also has an advantage that a waveguide having a simple structure such as a waveguide or a microwave transmission line can be used. As a result, the installation of the waveguide can be simply and easily installed independently on the existing back side of the ceiling or the indoor surface of the ceiling without modifying the existing indoor facilities such as the ceiling, lighting and air conditioning equipment. .

Further, the waveguide of the present invention can be used not only indoors but also in existing structures (outdoors, structures, roofs, arcades, etc.) above an appropriate height in the area.
Pillars, eaves, etc.) or structures newly installed or newly installed for waveguide installation (roofs, arcades, pillars, eaves, etc.). Further, not only the waveguide but also the wireless LAN system of the present invention can be easily constructed.

The size of these waveguides is determined according to the frequency used by the wireless LAN. In addition, the number of waveguides and branch circuits, or the spacing, etc., should be set so as to cover the entire communication range of the electromagnetic wave transmitting / receiving antenna of the slave unit, depending on the number of required wireless LAN slave units indoors. . In addition, the indoor desks 14a and 14b in FIG. 4 and the bookshelf 13 are used in consideration of the shielding of electromagnetic waves between the master unit and the slave unit of the wireless LAN and the influence of reflected waves. For example, when using two types of quasi-microwave band wireless LANs, the 2.4 GHz band and the 5.2 GHz band, provide two waveguides as shown in Figs.

By providing a plurality of these waveguides and changing the channels used, a plurality of channels can be used indoors. It is also possible to increase the individual communication speed in a large room or when there are many users who use wireless LAN.

Next, the master station antenna will be described. In the examples of Figs. 3 and 4 described above, the master station antennas 6a and 6b are arranged vertically downward toward the inside of the room, while the radiation angle of the main beam of the master station antenna is set to the indoor floor surface. Also, it may be diagonal. With such a configuration and arrangement, even if a part of the beam with a FWHM of the main beam from the master station antenna becomes a reflected wave from the ceiling surface, desk, floor, etc., these reflected waves Is preferable because it does not enter the slave unit covered by the master station antenna. This is because the beams of these reflected waves are propagated in the lateral direction and have different propagation directions from the diagonal main beam from the master station antenna. Therefore, when the condition of the indoor obstacle becomes particularly bad, the possibility of the electromagnetic wave reflected indoors due to the obstacle can be eliminated and the communication with high S / N can be guaranteed.

In FIGS. 3 and 4, the areas covered by the master station antennas may be discriminated by making the frequencies of the master station antennas different from each other. Further discrimination can be performed by performing the control together with the control of the radiation angle of the main beam of the master station antenna with respect to the floor surface.

The master station antenna may be configured as an array antenna other than the patch antenna. If it is configured as an array antenna, the radiation angle of the main beam of the master station antenna can be set in an oblique direction with respect to the indoor floor surface.
The antenna may have directivity toward the area. Further, since the shape of the antenna can be made small, it does not hinder the original indoor lighting and landscape when it is installed on the indoor ceiling.

The coupling degree between the waveguide and the radiated electric field of the parent station antenna may be variable, and the coupling degree may be increased as the parent station antenna is farther from the wireless LAN parent device. In this way, by increasing the degree of coupling for the master station antenna that is farther from the wireless LAN master device, the less power is supplied,
It is possible to eliminate the non-uniformity of the electromagnetic wave or the non-uniformity of the power radiation for each master station antenna.

Next, a preferable mode for further suppressing the reflected wave of the electromagnetic wave will be described. As a mode for this, the ceiling 11 of the building 10 may itself be configured by an electromagnetic wave absorber that weakly absorbs electromagnetic waves in a wide frequency band. This electromagnetic wave absorber is a known or commercially available electromagnetic wave absorber, such as a thin and laminated type, which is composed of a conductive layer or a metal magnetic material (powder) layer, as disclosed in JP-A-9-186485. The reflective material is appropriately selected. It should be noted that the ceiling itself may not be composed of the electromagnetic wave absorber, but the electromagnetic wave absorber may be attached to the surface of the ceiling material, a known or commercially available electromagnetic wave absorbing paint may be applied, or these may be combined.

Next, as a second embodiment, a case where the waveguide (high frequency line) is a microstrip line will be described with reference to FIG.
Will be described below. FIG. 10 is based on the packet communication, which is a feature of the present invention, and adds a mode in which a packet destination network address of a specific wireless LAN slave device and a specific branch circuit used for communication with the wireless LAN slave device are associated with each other. Here is an example: Even when the waveguide is a (high frequency) microstrip line, the basic configuration and control method are the same as those of the above-described waveguide type wireless LAN system of the present invention.

That is, in FIG. 10, the microstrip line 31a, which is a waveguide provided along the ceiling of the building 10.
Via a branch circuit 36a, 36b of a specific configuration, which will be described later,
The electromagnetic wave transmission / reception area and the electromagnetic waves of the child device to be covered between each parent station antenna (patcher antenna) in 36c and the child device group (terminal group) 39a, 39b, 39c placed indoors. An electromagnetic wave transmission / reception area of the transmission / reception antenna is formed to transmit / receive electromagnetic waves. One end of this microstrip line 31a is used as a non-reflective terminator 41, and the other end 40 is wirelessly connected via a coaxial cable (not shown) or the like.
LAN base unit 2a is connected.

Here, the microstrip line 31
The structure of a will be described below with reference to FIGS. 11 and 12. Figure 11
Shows an enlarged view of the microstrip line 31a, and FIG. 12 is a sectional view taken along the line AA of FIG.

As shown in FIG. 12, the microstrip line 31a has a structure in which a dielectric layer 32 made of a dielectric material and a signal line 34 made of a conductive material are sequentially laminated on a ground layer 33 made of a conductive material. It becomes. In addition, an adhesive layer for sticking (attaching) the line may be provided below the ground layer 33, and a deformation of the microstrip line 31a itself, such as further stacking a ground layer on the dielectric layer 32, is not required. , As appropriate.

Further, since the microstrip line itself is thin and flexible, it is not limited to a long plate shape, but a long coil shape in which the line is wound is easy to handle during manufacture, transportation, construction, etc. Is. Moreover, it has excellent basic characteristics as a high-frequency line, such as low loss of the high-frequency waves propagated.

However, even in the microstrip line, the amount of attenuation of high frequencies transmitted through the line inevitably varies depending on the position (location) where the branch circuit or patch antenna is attached to the line. Therefore, correspondingly, in order to ensure good communication with each cordless handset, the location of the branch circuit or patch antenna on the line (amount of high-frequency attenuation) allows the branch circuit or patch antenna to be connected to the line. It is necessary to adjust the degree of binding of to obtain the optimum degree of binding.

The degree of coupling is adjusted by changing the relative position of the central axis of the patch antenna with respect to the central axis of the signal line of the line, and adjusting the conditions such as the material and thickness of the radiation plate of the patch antenna and the dielectric. It is possible by

In the microstrip line,
In order to reduce the radiation loss, it is preferable to increase the dielectric constant of the dielectric layer 32. This dielectric constant is determined by the dielectric constant of the dielectric material itself forming the dielectric layer 32 and the thickness of the dielectric layer 32. Therefore, it is preferable to select the dielectric material and the thickness of the dielectric layer 32 so that the dielectric constant becomes high. However, as the material having a high dielectric constant and the thickness of the dielectric layer 32 become thicker, the flexibility becomes less. Therefore, when the flexibility is required, in consideration of this, the optimum material and the thickness of the dielectric layer 32 are taken into consideration. Select and.

On the other hand, the conductor loss increases as the electric conductivity of the signal line 34 increases, so that from the electric conductivity required for the line,
It is preferable to determine the optimum electrical conductivity of the signal line 34.
Furthermore, since the dielectric loss is determined by the dielectric material itself forming the dielectric layer 32, it is preferable to select a low dielectric loss material. For example, it is preferable to select and use a resin dielectric material having a low dielectric loss tangent of 0.02 or less, which is a measure (parameter) of dielectric loss, as a single composition or a composition in which a plurality of resin dielectric materials are mixed.

The width and thickness of the dielectric layer 2 are required to have a certain width and thickness because of the relationship between the signal frequency and the high frequency loss necessary for the wireless LAN system. In this respect, for example, with reference to a standard indoor wireless LAN system such as an office, it is preferable that the thickness is 0.1 to 2.0 mm and the width is about 10 to 50 mm.

The total thickness of the line is preferably as thin as 2 mm or less for the purpose of reducing the cross-sectional area and volume of the high-frequency line. Therefore, the thickness of the ground layer 3 and the signal line 4 is preferably as thin as possible for this purpose. The thickness of the ground layer 3 is preferably 0.2 mm or less if the required thin plate strength can be guaranteed.
The width of the ground layer 3 corresponds to the width of the dielectric layer 2 in order to cover the dielectric layer 2 and suppress high frequency loss.

The conductive material forming the ground layer 33 is
Metals and alloys such as copper, aluminum, tin, gold, nickel and solder, and various modes in which these metals and alloys are respectively compounded, laminated, or plated on a resin substrate are appropriately selected as the good conductive metal material. To be done. Among these,
A metal material that can be easily processed into a thin plate, has a flexibility commensurate with the above-mentioned dielectric material, and has a necessary thin plate strength is preferable.

For the signal line 4 for high frequency induction, a thin wire or a thin plate made of the above-mentioned highly conductive metal material is selected.

The conductive material forming the patch 37 is
The same metal material as the conductive material forming the ground layer of the line can be applied. As the dielectric material forming the dielectric 38, the same material as the low-loss resin dielectric material forming the dielectric of the microstrip line is selected.

The configuration of the branch circuit 36 will also be described below. 11, one branch circuit 36 is arranged on each side of the signal line 34 of the microstrip line 31a. Then, as shown in FIG. 10, a branch circuit such as this FIG. 11 or a later-described FIG. 14 is arranged on the microstrip line 31a at distances (intervals) L1, L2, and L3 to form branch circuits 36a to 36c. Each is arranged.

As shown in FIG. 11, the branch circuit 36 is basically composed of a patch 37 connected to the branch switch 27b, a control signal line 20b also serving as the power supply line 29, and an electrical coupling portion 35 with the signal line 34 of the circuit. become. Further, as shown in FIG. 13 described later, the branch switch 27b is connected with a terminating resistor 30b on the non-selected side, and although not shown, it is connected to the ground layer 33 of the microstrip line 31a. The patch 37 is a flat plate made of a conductive material, and a dielectric layer made of a lower dielectric material.
Stacked with 38 to form a patch antenna.

By the structure of the above patch (antenna),
The antenna can be easily attached to and detached from the microstrip line. Therefore, even if there is a change in the antenna layout of the wireless LAN system such as a change in the office layout, if the microstrip line can cover the entire area, basically, the patch layout is changed according to the new layout. All you have to do is attach or remove the antenna, and you do not have to redo the installation work for the track itself.

Also, when it is necessary to correct the radio frequency to be used with respect to the main characteristics such as coupling degree and gain of the antenna, the conditions such as the material and thickness of the radiation plate and the dielectric on the patch antenna side are required. It can be easily corrected by using a patch antenna that is adjusted or adjusted to the applicable conditions.

A branch switch in the branch circuit 36
27b, as shown in FIG. 13 which is a circuit diagram of FIG. 11, in accordance with a control signal from the antenna control unit 17 of FIG. 10 via the control signal line 20b, the patch 37 and the (signal line 34 Open and close the connection with the joint 35. Thus, for example, when the control signal from the antenna control unit 17 is in the ON state, the coupling unit 35 (microstrip line 31a) and the patch
(Antenna) 37 is coupled, and electromagnetic waves are radiated from the patch (antenna) 37 toward the specific handset. On the other hand, when the control signal from the antenna control unit 17 is OFF, the coupling unit 35 is connected to the terminating resistor, and the microstrip line 31a (signal line 34) that is a waveguide and the patch (antenna) 37 that is a master station antenna are connected. Is not combined with and no electromagnetic waves are emitted.

FIG. 14 shows another mode of the branch circuit 36. Figure
In the branch circuits 36a and 36b in 14, the branch switch 27c is directly inserted in the signal line 34.
At c, the patch (antenna) 37 is electrically coupled to the signal line 34 via coupling portions 35a and 35b.

Then, the branch circuit 36a (the same applies to 36b) of FIG.
The branch switch 27c in FIG. 15 is a circuit diagram of FIG.
As shown in, the connection between the patch 37a and the signal line 34 of the microstrip line 31a is opened and closed according to the control signal from the antenna control unit 17 via the control signal line 20c. Thus, for example, when the control signal from the antenna control unit 17 turns on the branch circuit 36a, the signal line 34 and the patch (antenna) 37a are coupled to each other, and the patch (antenna) 37a Electromagnetic waves are emitted into the area. On the other hand, in the OFF state, the microstrip line
The signal lines 34 of 31a are connected to each other, and the signal line 34 and the patch (antenna) 37a which is the master station antenna are not coupled. Therefore, the high-frequency signal passes through the branch circuit 36a as it is and flows on the microstrip line 31a.

However, in this embodiment of the branch circuit, unlike the embodiment of the branch circuit described above, the branch switch is directly inserted in the signal line 34. Therefore, when the upstream branch circuit 36a is selected and coupled in accordance with the control signal from the antenna control unit 17 in FIG. 10, the downstream branch circuit 36a is selected.
After b, no high-frequency signal flows through the microstrip line 31a. In other words, if one branch circuit is selected, it will not be able to receive any signals from other branch circuits. For example, when the branch circuit 36a of FIG. 14 is selected, even if another branch circuit 36b or the like is selected, the signal from the other branch circuit 36b does not reach the master device 2a of FIG. . For this reason, in the embodiment of this branch circuit, as shown in FIG.
The branching method can be used only by the polling control described in.

On the other hand, in this embodiment of the branch circuit, all the electric power from the master unit 2a shown in FIG. 10 always reaches the one selected branch circuit, and the total electric power is radiated from the one selected patch antenna. Therefore, there is an advantage that power efficiency is high. For example, in the embodiment of the coupling type branch circuit of FIG. 11, the power coupling from the waveguide is always generated in each branch circuit regardless of which branch circuit is selected. Therefore, in the coupled branch circuit, power is lost in the unselected branch circuit due to each of the terminating resistors, and the power efficiency is lower than that of the insertion type branch circuit.

In the apparatus configuration as described above, in FIG.
As shown in Fig. 1, the antenna control unit
Reference numeral 17 indicates a packet destination network address of the wireless LAN slaves 39a, 39b, and 39c, and a patch (antenna) provided in each branch circuit 36a, 36b, and 36c to be used for communication with the wireless LAN slaves in advance. Has the correspondence relationship of the slave unit (slave station) as a reference table 18. Then, when data is transmitted from the wireless LAN base unit 2a to a specific wireless LAN slave unit, the packet transmission destination network address of the specific slave unit is designated and sent to the antenna control unit 17 as a control signal 9. The antenna control unit 17, which has been sent the control signal 9, identifies the wireless LAN slave device from the network address, and the specific wireless LA
A specific master station antenna to be used when communicating with the N slave unit is determined by referring to the reference table 18.

Thereafter, the antenna control section 17 turns on only the branch circuit (branch switch module) connected to the determined specific master station antenna, and turns on the other branch circuits by the signal line 20 (20a to 20c). Turn off via line 20.
As a result, the electromagnetic waves currently transmitted from the wireless LAN base unit 2a reach the specific slave unit only through the specific master station antenna selected from the microstrip line 31a. Therefore, the problem of multipath interference can be solved by uniquely determining the communication path from the wireless LAN master unit 2a to the slave unit.

Further, even in the case of a wireless LAN system in which the waveguide has a plurality of branch circuits or in the case of a plurality of wireless LAN parent devices, a plurality of master station antennas are not coupled to the waveguide at the same time. For this reason, the wireless LAN parent device transmits data to the specific child device only through the route through the master station antenna, and there is no concern that a multipath route like that through another master station antenna occurs.

Furthermore, in addition to the embodiment of FIG.
By using the communication control method between the parent device and the child device of the polling method described in the above, communication is possible without causing the problem of multipath interference occurring in the waveguide. That is, even in the case of a wireless LAN system in which the waveguide has a plurality of branch circuits or when there are a plurality of wireless LAN master units, the master unit keeps track of the communication timing with each slave unit, and therefore communicates with each slave unit. It selects the optimum master station antenna to perform the communication, and enables communication without causing the problem of multipath interference that occurs in the waveguide. Also,
Limit the communication route, including the time of transmission from the slave to the master,
By limiting the master station antenna to be used, it is possible to avoid multipath interference in both directions.

[0098]

As described above, the radio according to the present invention
With the LAN system, it is possible to provide a wireless LAN system in which even if the frequency of electromagnetic waves used for communication is low, multipath fading due to the plurality of communication paths can be suppressed and the effective speed of communication does not decrease. Further, the wireless LAN system according to the present invention has no restrictions on the arrangement of the wireless LAN base unit, has a high degree of freedom in installation, and is easy to install. Furthermore, multiple channels can be used within an area, and individual communication speed can be increased even in a large area, indoors, or when many users use a wireless LAN. The scale and number of wireless LAN system series can be arbitrarily expanded according to the application and need. Therefore, the wireless LAN system,
Not only indoors, but also waveguides not only indoors but also in outdoor areas, arcades such as shopping streets, station platforms, airport terminals, large temporary structures such as tents, and wireless LAN systems in certain areas such as event venues. If there is a structure such as a roof that can be installed, or you can easily install a new structure and install a waveguide without it, etc.
Its industrial value is great because it can be expanded in application and can be applied to mobile communication using wireless.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a wireless LAN system of the present invention using a waveguide.

FIG. 2 is an explanatory diagram showing a communication status of the wireless LAN system of FIG.

FIG. 3 is a perspective view showing a configuration of a wireless LAN system which is a premise of FIG.

4 is a cross-sectional view taken along the line AA of FIG.

FIG. 5 is an explanatory diagram showing a packet communication system.

6 is a plan view showing the results of a multipath interference test according to the embodiment of FIG.

FIG. 7 is a sectional view showing an example of a branch circuit in the wireless LAN system of the present invention.

8 is a plan view showing the back surface of the radiation plate 22 in FIG. 7. FIG.

FIG. 9 is a circuit diagram of FIG.

FIG. 10 is a radio of the present invention using a microstrip line.
It is explanatory drawing which shows another embodiment of a LAN system.

FIG. 11 is a sectional view showing an example of a microstrip line in the wireless LAN system of the present invention.

12 is a cross-sectional view taken along the line AA of FIG.

FIG. 13 is a circuit diagram of FIG. 11.

FIG. 14 is a plan view showing another aspect of the branch circuit in the wireless LAN system of the present invention.

FIG. 15 is a circuit diagram of FIG.

[Explanation of symbols]

1: Waveguide, 2: Wireless LAN base unit, 3: Wireless LAN slave unit,
4: waveguide end, 5: branch circuit, 6: master station antenna,
7: Handset antenna, 8: OA equipment, 9: Opening, 10: Building, 1
1: Ceiling, 12: Coaxial-waveguide converter, 13: Bookcase, 14:
Desk, 15: cable, 16: door, 17: antenna controller, 18
: Reference table, 19: Backbone network, 2
0: signal line 21: coupling conductor, 22: radiation plate, 23: ground layer, 24: insulating material, 25: dielectric layer, 26: patch antenna, 27: branch switch, 28: coupling conductor connection part, 29 : Power supply line, 30: Terminating resistor, 31: Microstrip line, 32: Dielectric layer, 33: Ground layer, 3
4: signal line, 35: coupling part, 36: branch circuit, 37: patch,
38: Dielectric layer, 39: Remote unit, 40: One end of high frequency line, 4
1: non-reflective terminator,

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takuya Kusaka             1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture             Kobe Steel Co., Ltd.Kobe Research Institute F term (reference) 5K033 AA05 CA01 DA01 DA17 DB01                 5K067 AA02 BB02 BB21 DD11 DD51                       EE02 EE10 HH22

Claims (10)

[Claims] 1. A waveguide provided along an area forming a wireless communication network, a wireless LAN master device connected to the waveguide, and a wireless LAN slave device arranged in the area. Then
The waveguide has a plurality of branch circuits, each branch circuit is connected to an electromagnetic wave transmitting / receiving antenna having directivity toward the area, and the wireless LAN is provided in a packet system.
Wireless for data communication between the base unit and the wireless LAN handset
In a LAN system, a packet destination network address of a specific wireless LAN slave device and a specific branch circuit used for communication with the wireless LAN slave device are previously associated with each other, and according to the network address of the packet to be communicated. , A wireless LAN system characterized by selectively opening a specific branch circuit associated with this address. 2. A wireless LAN with which the wireless LAN base unit communicates
It has a list of slave units, and polls the wireless LAN slave units in order according to this list to grasp the communication timing between the master unit and each slave unit. The wireless LAN system according to claim 1, wherein a specific branch circuit to be opened during a period during communication of is selected. 3. The wireless LAN system according to claim 1, wherein the waveguide is a waveguide. 4. The branch circuit comprises a rod-shaped coupling conductor and a radiation plate attached to one end of the coupling conductor, and the coupling conductor has an insulating material interposed in a hole provided in the waveguide. And the radiation plate is directed toward the inside of the area, and a patch antenna is formed on the area inside surface of the radiation plate,
The wireless LAN system according to claim 3, further comprising a branch switch that opens and closes a connection between the patch antenna and a radiation plate connection portion of the coupling conductor according to a control signal. 5. The wireless LAN system according to claim 1, wherein the waveguide is a microstrip line. 6. The microstrip line has a structure in which a dielectric layer made of a dielectric material and a signal line made of a conductor material are sequentially laminated on a ground layer made of a conductor material, and a dielectric layer made of a dielectric material is used. A patch antenna in which a body plate and a patch made of a conductive material are sequentially laminated is electrically coupled to the signal line, and further, a branch switch for opening and closing the connection between the signal line and the patch antenna according to a control signal. The wireless LAN according to claim 5, wherein the wireless LAN is provided.
system. 7. The patch antenna is electrically coupled to the signal line via a coupling portion, and the branch switch is provided to open and close a connection between the coupling portion and the patch antenna. The wireless LAN system according to Item 6. 8. The wireless LAN system according to claim 6, wherein the branch switch is inserted in the signal line, and the patch antenna is electrically coupled to the branch switch. 9. The wireless LAN system is for indoor use,
The wireless LAN system according to claim 1, wherein the area is indoors. 10. The wireless LAN according to claim 1, wherein the waveguide is provided along the indoor ceiling.
system.