JPH03283725A - Radio communication system - Google Patents

Abstract

PURPOSE:To decrease a radio zone by providing lots of remote relay stations only amplifying a microwave signal and interconnecting the base station and the remote relay station with an optical fiber through which an optical signal is sent while converting the multiplexed microwave signal into the optical signal. CONSTITUTION:A terminal station equipment 1 applies time division multiplex or frequency division multiplex to plural series of signals sent from a converter 3 toward plural subscriber radio stations 11-15 to obtain a microwave band transmission signal. Then a microwave/optical converter 2 uses a multiplexed microwave signal so as to apply analog modulation to the light directly and the modulated light is sent to remote relay stations 21, 22 through optical fibers 4, 5. Then the remote relay station amplifies the obtained microwave signal and sends the result from an antenna to subscriber radio stations 11-15. In the case of communication from the subscriber to the base station, the remote relay stations 21, 22 convert signals from plural subscribers into an optical signal without modification and frequency conversion and send the signal to the base station through an optical fiber reversely. Thus, the radio zone is made small economically.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a communication system for performing subscriber-based transmission connecting a relay network and subscribers in a public communication network.

[Prior Art] Conventionally, systems for performing subscriber transmission include those using wireless communication, and those using optical fiber cables (hereinafter simply referred to as optical fibers) or metallic cables. Among these, wireless communications do not require cable laying work, so they have the advantage of allowing quick, flexible, and economical line setup.

An example of a conventional configuration of this wireless subscriber transmission system is shown in FIG. In this example, a terminal device 1 located at a base station is connected to an exchange 3 for a plurality of subscriber radio stations 51 to 54.
A transmission signal in the microwave band is obtained by time-division multiplexing or frequency-division multiplexing of multiple series of signals.

That is, the base station assigns each subscriber radio station an individual time slot or carrier frequency. This multiplexed transmission signal is transmitted from the base station transceiver 66 to the plurality of subscriber radio stations 51 to 54. Each subscriber radio station extracts the signals intended for itself from among the received signals.

On the other hand, in communication from a subscriber to a base station, the subscriber wireless station sends out a microwave signal toward the base station using the time slot or carrier frequency assigned to the subscriber station. The base station transmitting/receiving device 66 receives signals transmitted from each subscriber wireless station, and the terminal device 61 separates the signals into multiple series of signals.

[Problems to be Solved by the Invention] In such a wireless communication system for multiple wireless stations, the smaller the area over which one base station transmits power, the lower the transmission power can be. This is advantageous in terms of frequency reduction, etc., and frequency utilization efficiency is also improved. Furthermore, the influence of microwave attenuation due to rain or the like can be reduced.

However, since the base station requires a control device, a modulation/demodulation device, and a frequency conversion device for allocating time slots or carrier frequencies, the configuration is complicated and the scale is large. For this reason,
Conventionally, there has been a problem in that reducing the area covered by one base station requires increasing the number of base stations, which is uneconomical.

The present invention aims to solve these problems and reduce the size of one wireless zone without increasing the number of large-scale base stations.

[Means for Solving the Problems] The present invention has been accomplished in order to solve the above-mentioned problems and achieve the above-mentioned objects.

That is, the present invention configures a system including a base station, a plurality of remote relay stations connected to the base station by optical fibers, and a plurality of wireless stations connected to the remote relay station by wireless lines. Modulate light with a radio frequency signal obtained by multiplexing multiple series of signals using time division or frequency division methods, transmit the modulated light to a remote relay station via optical fiber, and detect the light at the remote radio station. The base station communicates with multiple wireless stations by transmitting the radio frequency signals obtained from the radio frequency signals to multiple wireless stations, while the radio frequency signals transmitted from multiple wireless stations are transmitted all at once at a remote relay station. Wireless communication that performs communication from multiple wireless stations to the base station by transmitting the received and modulated light with this composite signal to the base station via optical fiber, and detecting the light at the base station to obtain a radio frequency signal. It is a method.

[Function] As described above, in the present invention, in addition to the base station that collectively performs line control, multiplexing, and modulation/demodulation, a large number of remote relay stations that only amplify microwave signals are provided, and the base station The connection between the remote relay station and the remote relay station is made by converting the multiplexed microwave signal directly into an optical signal and transmitting this signal through an optical fiber.

Therefore, the wireless zone can be made smaller by providing a large number of relay wireless stations. In addition, since the function of a remote relay station is only to detect optical signals and amplify the resulting microwave signal, it can have a simpler configuration than a base station, so it is possible to increase the number of base stations. The system can be constructed more economically than the conventional method of reducing the size of the wireless zone.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 shows a system configuration of an embodiment of the present invention. In the figure, 2 is a microwave/optical converter that converts multiplexed microwave signals and optical signals, 4.5 is an optical fiber, and 21.22 is a microwave/optical converter that converts optical signals and microwave signals and is multiplexed. represents a remote relay station that amplifies wave signals.

First, the communication path from the base station side to the subscriber side will be explained. As in the conventional example, the terminal equipment 1 performs time-division multiplexing or frequency-division multiplexing on multiple series of signals sent from the exchange 3 to multiple subscriber radio stations 11 to 15 to transmit microwave band transmission signals. obtain.

Next, the microwave/optical converter 2 directly analog modulates the light with the multiplexed microwave signal.

The modulated light is transmitted to a remote relay station 21 via an optical fiber 4.5.
．． 22. The remote relay station obtains the original multiplexed microwave signal by detecting the transmitted optical signal. Next, the remote relay station amplifies the obtained microwave signal and transmits it to the subscriber radio stations 11-15 via an antenna.

In communication from the subscriber side to the base station side, a remote relay station receives signals from multiple subscribers, converts them directly into optical signals without frequency conversion, and transmits them to the base station via optical fiber in the opposite path. Transmit to.

The subscriber station need only operate in exactly the same way as in the conventional system without optical fiber transmission, and the remote repeater station only needs to convert optical signals to microwave signals and amplify the microwave signals.

In this embodiment, the number of wireless zones can be increased by simply providing remote relay stations with a simple configuration without increasing the number of base stations. Therefore, the size of each wireless zone can be reduced by economical system configuration.

[Effects of the Invention] As explained above, according to the present invention, the wireless zone can be economically reduced, the transmission power can be reduced to simplify the subscriber wireless station, and the attenuation of microwaves due to rain etc. can be reduced. This has the advantage of reducing the impact of

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a system configuration according to an embodiment of the present invention, and FIG. 2 is a diagram showing an example of a conventional system configuration.

Claims (1)

[Claims] A system comprising a base station, a plurality of remote relay stations connected to the base station by an optical fiber cable, and a plurality of wireless stations connected to the remote relay station by a wireless line, the base station The optical signal is modulated with a radio frequency signal obtained by multiplexing multiple series of signals using a time division or frequency division method, and the modulated optical signal is transmitted to a remote relay station via an optical fiber cable. The base station communicates with the multiple wireless stations by detecting the optical signal and transmitting the radio frequency signal to the multiple wireless stations, and the radio frequency signals transmitted from the multiple wireless stations are transmitted to the remote relay station. The optical signal modulated by this composite signal is transmitted to the base station via an optical fiber cable, and the base station detects the light to obtain a radio frequency signal, allowing communication from multiple wireless stations to the base station. A wireless communication method characterized by the following: