JPH09233050A - Radio network system and optical transmission method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily realize installation of a repeater at a low cost in the radio network system such as a radio local area network(LAN). SOLUTION: Plural information terminal equipments T each having a radio communication function are provided and communication of information among the information terminal equipments T is conducted by using a radio signal subject to spread spectrum modulation. In this case, plural repeaters E are connected by an optical fiber transmission line N and the information terminal equipment T makes communication of information by the radio signal subject to spread spectrum modulation. The repeater E is provided with a transmitter- receiver 3 making radio communication with the information terminal equipment T, an electrooptic converter 4 applying intensity modulation to an optical signal based on the received spread spectrum modulation signal and outputting the signal to an optical fiber transmission line N, and anoptoelectric converter 5 demodulating the optical signal received from the optical fiber transmission line N into the original spread spectrum modulation signal and outputting the signal to the transmitter-receiver 3, and the communication of information is conducted between the repeaters E by using an optical signal through the optical fiber transmission line N.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a so-called wireless LAN.
The present invention relates to a wireless network system called (Local Area Network), and particularly to a wireless network system that relays information communication between terminal devices via a relay system using an optical transmission path such as an optical fiber. The present invention also relates to a method for converting a signal subjected to spread spectrum modulation to an optical signal and transmitting the optical signal, and particularly to an optical transmission method suitable for use in the relay system of the wireless network.

[0002]

2. Description of the Related Art Currently, a system is widely used in which a plurality of information terminal devices such as personal computers are connected by a LAN and information communication is performed between these information terminal devices through the LAN. In a general LAN, a plurality of information terminal devices are connected by a cable, and information communication is performed between these information terminal devices through the cable.
However, LAN using such cable connection
In that case, since it is necessary to connect a cable to each information terminal device, if the information terminal device is to be relocated or added, a laborious and costly wiring work must be performed. There was a problem that so-called portability was impaired.

In order to solve the drawbacks of the LAN due to such cable connection, a wireless LAN has been put into practical use in which information communication is wirelessly performed between information terminal devices. This wireless LAN eliminates the cable connecting the information terminal devices by providing the information terminal device with a wireless communication function, and facilitates the relocation or extension of the information terminal devices. In order to achieve a communication speed equivalent to that of a cable-connected LAN in such a wireless LAN, the transmission frequency used for information communication must be increased, and at present, microwaves of several GHz or higher are required. The obi is used. Further, since the LAN is used to perform information communication within a limited range such as in a business office, the transmission output of the wireless LAN is relatively low and the wireless communication distance is relatively short. Has become.

Further, as a signal communication system, a spread spectrum modulation system is known in which a signal is spread and transmitted in a frequency band much wider than a frequency band required for transmitting information. This spread spectrum modulation system has various characteristics superior to those of other communication systems and is used in wireless communication.

[0005]

[Problems to be Solved by the Invention] Such a wireless LAN
However, there are cases where a relatively long communication distance is required. For example, not only when the area of the LAN expands in a circle, but there is a case where the area of the LAN needs to be elongated and elongated depending on the place where the LAN is laid. In such a case, a plurality of relay stations connected to each other by a cable are provided, wireless communication is performed between the information terminal device and the relay station, and communication is performed between the relay stations through the cable to increase the communication distance. A method can be considered. However, wireless LAN
Since the low output signal of high frequency is used in,
In order to carry out communication between relay stations while suppressing transmission loss, it is necessary to connect between relay stations with a large diameter metal wire cable, and laying relay stations requires time-consuming and costly wiring work. There is the problem of having to do it.

Further, even when the spread spectrum modulation method is used for wireless communication between the information terminal device and the relay station, the modulated signal has a wide frequency band, so that the microwave band of several GHz or more is used. It becomes a high frequency thing such as. For this reason, when communicating a spread spectrum modulated signal between relay stations, in order to suppress transmission loss, it is necessary to connect between relay stations with a large diameter metal wire cable, and the same problem as above. Was occurring.

The present invention has been made in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a wireless network system, such as a wireless LAN, which can easily and inexpensively lay a relay station. . It is another object of the present invention to provide a method for easily laying a transmission line at low cost when converting a spread spectrum modulated signal into an optical signal for transmission. Another object of the present invention is to provide an optical transmission method suitable for use in a relay system of a wireless network.

[0008]

Here, as a transmission method used in the field of wired video broadcasting and the like, there is a method of transmitting a radio frequency signal by light. This transmission method is an SCM (sub carrier multiplexing) modulation method in which light such as laser light is intensity-modulated by a signal of a radio frequency to be transmitted, and this intensity-modulated optical signal is transmitted through an optical fiber, and this optical signal is transmitted. On the receiving side, the optical signal is demodulated into an electric signal to obtain the original radio frequency signal.

In order to achieve the above object, the present invention applies the above-mentioned transmission method to optical transmission of a spread spectrum modulated signal, and converts the spread spectrum modulated transmission signal into an optical signal. When transmitting from the transmitting side device to the receiving side device, the transmitting side device transmits an optical signal intensity-modulated by the spread spectrum modulated transmission signal through an optical transmission line such as an optical fiber transmission line, and the receiving side device, It is characterized in that an optical signal is received from an optical transmission line and a transmission signal which is spread spectrum modulated is received by demodulating the optical signal.

In the optical transmission method according to the present invention, intensity conversion of the optical signal is performed by the spread spectrum modulated signal and demodulation in the opposite direction is performed to perform conversion processing between the spread spectrum modulated signal and the optical signal. Communication using an optical fiber or the like is realized by an optical signal obtained by converting a signal subjected to spread spectrum modulation. Since the optical fiber has a diameter smaller than that of the metal wire cable and the laying work is easy, the optical fiber can be laid easily and at low cost. Further, for example, the optical transmission line may be configured by spatial optical transmission using infrared light, and even in such spatial optical transmission, the intended purpose can be achieved if the transmission distance is longer than that of the wireless LAN. .

In order to achieve the above object, the present invention applies the above-mentioned optical transmission system to a wireless network and comprises a plurality of information terminal devices having a wireless communication function. In a wireless network system in which information communication between devices is performed wirelessly, a plurality of relay devices are connected by an optical transmission line such as an optical fiber transmission line, and an information terminal device wirelessly communicates with the relay device. The relay device is configured to perform information communication, and the relay device is a communication means for performing wireless communication with the information terminal device, and an electric-optical conversion for intensity-modulating an optical signal based on a wireless signal received by the communication means and outputting the optical signal to an optical transmission line. And an optical-electrical conversion unit that demodulates an optical signal received from the optical transmission line into an electric signal and outputs the electric signal to the communication unit.

In the wireless network system according to the present invention, information communication is performed wirelessly between the information terminal device and the relay device, and information communication is performed between the relay devices by optical communication through an optical transmission path. In this repeater, intensity conversion of an optical signal based on a wireless signal and demodulation of the opposite are performed to perform conversion processing between a wireless signal and an optical signal, and optical communication is performed by an optical signal obtained by converting the wireless signal. Has been realized. Since the optical fiber has a diameter smaller than that of the metal wire cable and the laying work is easy, the line connecting the relay devices can be laid easily and at low cost, and the communication area in the wireless LAN can be easily expanded. You can Further, for example, the optical transmission line may be configured by spatial optical transmission using infrared light, and even in such spatial optical transmission, the intended purpose can be achieved if the transmission distance is longer than that of the wireless LAN. .

In order to achieve the above object, the present invention applies the above-mentioned wireless network to the transmission of a spread spectrum modulated signal, and the information terminal device is spread spectrum modulated with the relay device. The signal is used for wireless communication, and the electro-optical converting means intensity-modulates the optical signal based on the spread spectrum modulated signal and outputs the optical signal to the optical transmission line. In the wireless network system according to the present invention, it is possible to expand the communication area in the wireless LAN easily and at low cost while exhibiting the excellent characteristics of the spread spectrum modulation method.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A wireless network system according to an embodiment of the present invention will be described with reference to FIG. The wireless network system of the present embodiment is provided with a plurality of information terminal devices T each having a wireless communication device attached to a personal computer, and these information terminal devices T wirelessly communicate information with a repeater E via an antenna 1. Will be done at. A plurality of repeaters E are also provided, and the repeaters E are connected to each other by an optical transmission line N made of an optical fiber. The optical transmission line N can also be configured by spatial transmission using infrared light.

The repeater E includes an information terminal device T and an antenna 2
A transmitter / receiver 3 for performing wireless communication via the optical transmission line N, an electro-optical converter 4 for outputting an optical signal intensity-modulated based on the radio signal received by the transmitter / receiver 3 to the optical transmission line N, and received from the optical transmission line N. The optical-electrical converter 5 that demodulates the optical signal into an electric signal and outputs the electric signal to the transceiver 3. The transmitter / receiver 3 is a known transmitter / receiver having a modulation / demodulation function, and performs wireless communication with the information terminal device T.

The electro-optical converter 4 has a light emitting element (LED) that emits a laser beam and a modulator that controls the modulation of the light emitting element by a radio signal to be transmitted, and is output from the light emitting element. The optical beam is subjected to analog signal modulation processing by a wireless signal, the wireless signal is converted into an optical signal, and the optical signal is output to the optical transmission line N. The optical-electrical converter 5 includes a photoelectric element that converts an optical signal into an electric signal and a demodulator that extracts a radio signal of a predetermined frequency from the electric signal. The reverse process is performed and the optical transmission line N
The optical signal received from is converted into a wireless signal and output to the transceiver 3.

According to the wireless network system having the above configuration, the information wirelessly transmitted from a certain information terminal device T is:
The signal is received by the repeater E in the area covering the information terminal device T, converted into an optical signal by the electro-optical converter 4, and then transmitted via the optical transmission line N. This optical signal is received by the repeater E in the area covering the destination information terminal device, converted into an electrical signal by the optical-electrical converter 5, and then wirelessly transmitted from the transceiver 3 to the destination information terminal device T. .

Therefore, since the relay path for optical communication is interposed in the wireless communication path between the information processing apparatuses T, even if the high frequency and low output wireless signal is used, the information processing apparatuses T are relatively distant from each other. Information communication can be performed without any trouble. Since the information communication is performed by the optical signal instead of the electric signal, the relay path can be configured by the optical fiber having the small diameter and the laying work is easy, and the information terminal device T has the excellent flexibility of the wireless network. The communication area can be expanded easily and at low cost in the system.

FIG. 2 shows a wireless network system according to another embodiment of the present invention. The same parts as those in the above-described embodiment are designated by the same reference numerals, and the duplicated description will be omitted. In the wireless network system of the present embodiment, an information controller C is provided between the repeaters E, the optical transmission line N from each repeater E is connected to the information controller C, and the information controller C is connected to the information controller C.
It is a star-shaped relay path centered around.
The information controller C includes an optical-electrical converter 6 that converts an optical signal received from the optical transmission line N into an electrical signal, and an electrical-optical conversion that converts the electrical signal into an optical signal and transmits the optical signal to the optical transmission line N. Bowl 7
Then, a radio frequency signal is extracted from the electric signal converted by the optical-electrical converter 6 and demodulated into information, or the information-converted signal is modulated into a radio frequency signal, and the signal is transferred to the electric-optical converter 7. A modulator / demodulator 8 for outputting and an information processor 9 for performing processing such as copy storage, conversion, transfer, etc. on the information extracted from the optical signal as necessary are provided.

According to the wireless network system of this embodiment, information wirelessly transmitted from a certain information terminal device T is
The signal is received by the repeater E in the area covering the information terminal device T, converted into an optical signal by the electro-optical converter 4, and then transmitted via the optical transmission line N. This optical signal is once converted into information in the information controller C, and the information processor 9
Necessary processing is performed by. And the information processing device C
The information which has been subjected to the process (1) or which passes through without any process is converted again into an optical signal by the modulator / demodulator 8 and the electro-optical converter 7 and transmitted to the optical transmission line N. This optical signal is received by the repeater E in the area covering the destination information terminal device T, converted into an electrical signal by the optical-electrical converter 5, and then wirelessly transmitted from the transceiver 3 to the destination information terminal device T. It

Also in this embodiment, similarly to the above embodiment, even if a high frequency and low output radio signal is used, information communication between information processing devices T relatively distant from each other can be performed without any trouble. Therefore, the communication area can be expanded easily and at low cost in the wireless network system in which the information terminal device T is highly versatile. In each of the above-described embodiments, a wireless network including a plurality of personal computers is taken as an example, but the present invention is configured with various information terminal devices having a wireless communication function such as a mobile phone and a private wireless device. It can also be applied to the wireless network.

Further, in each of the above-mentioned embodiments, the radio communication between the information terminal device T and the repeater E can be performed by a signal subjected to spread spectrum modulation. In the case of transmitting a signal that has been spread spectrum modulated in this way, FIG.
2, the electro-optical converter 4 intensity-modulates the optical signal by the spread spectrum modulation signal received by the transmitter / receiver 3 and outputs it to the optical transmission line N, and the optical-electrical converter 5 transmits the optical signal. The original spread spectrum modulated signal obtained by demodulating the optical signal received from the path N is output to the transceiver 3.

By converting the signal subjected to the spread spectrum modulation into an optical signal and transmitting it, a signal of a relatively high frequency can be transmitted over a long distance with low loss. The optical transmission for the spread spectrum modulated signal can be applied not only to the wireless network but also to various communication systems that perform communication by the spread spectrum modulated signal.

[0024]

As described above, according to the wireless network system of the present invention, since the optical transmission line for performing optical communication is interposed in the wireless communication route between the information processing devices, it is originally used in the wireless network system. Even with the high-frequency and low-output wireless signal, the information communication between the information processing devices that are relatively distant from each other can be performed without any trouble. Furthermore, since the relay path is configured by the optical transmission path, it is possible to easily and inexpensively expand the communication area in the wireless network system while maintaining the flexibility of the information terminal device. Further, according to the optical transmission method of the present invention, since the spread spectrum modulated signal is converted into an optical signal and transmitted, an optical transmission line which can be realized easily and at low cost can provide a high frequency signal. Can be transmitted over a long distance with low loss.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a wireless network system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a wireless network system according to another embodiment of the present invention.

FIG. 3 is a diagram showing an example of an optical transmission method according to the present invention.

[Explanation of symbols]

T ... Information terminal device, E ... Repeater, N ...
Optical transmission line, 3 ... Transceiver, 4 ... Electric-optical converter, 5 ... Optical-electric converter,

Claims (3)

[Claims] 1. A method of converting a spread spectrum modulated transmission signal into an optical signal and transmitting the optical signal from a transmission side apparatus to a reception side apparatus, wherein the transmission side apparatus performs intensity modulation with the spread spectrum modulated transmission signal. An optical device characterized in that an optical signal is transmitted through an optical transmission line, and a receiving side device receives the optical signal from the optical transmission line and receives a spread spectrum modulated transmission signal by demodulating the optical signal. Transmission method. 2. A wireless network system comprising a plurality of information terminal devices having a wireless communication function, wherein information communication between these information terminal devices is performed wirelessly, wherein the system comprises a plurality of relay devices as optical transmission lines. The information terminal device is configured to wirelessly perform information communication with the relay device, and the relay device is configured to communicate with the information terminal device wirelessly based on the communication means and the wireless signal received by the communication means. An electric-optical conversion unit that intensity-modulates the signal and outputs it to the optical transmission line, and an optical-electrical conversion unit that demodulates the optical signal received from the optical transmission line into an electric signal and outputs the electric signal to the communication unit are provided. A wireless network system characterized by the above. 3. The wireless network system according to claim 2, wherein the information terminal device performs wireless communication with the relay device by a spread spectrum modulated signal, and the electro-optical converting means performs a spread spectrum modulated signal. A wireless network system, which intensity-modulates an optical signal based on the above and outputs it to an optical transmission line.