JPH01181344A - Radio communication system - Google Patents

Abstract

PURPOSE:To miniaturize the transmitter of a peripheral station by devising the peripheral station such that the station transmitting a data signal and a voice signal in parallel simultaneously processes the voice signal into a burst signal and transmitting the data signal and the voice signal in frequency division. CONSTITUTION:Modulators 10, 17 constitute modulation means modulating carriers 1, 2 in different frequencies f1, f2 from a data signal subjected to packet processing and a voice signal subjected to burst processing, and a timing control section 7 and a switch 12 constitute a transmission control means as a whole. In case of the parallel and simultaneous transmission of the data signal and the voice signal from the peripheral station to the center station, the peripheral station uses different carriers 1, 2 from the data and voice signals, but the peripheral station taking an optional point of time switches the carrier so as to transmit only one carrier of either of the modulated carrier 1 relating to a data signal or the modulated carrier 2 relating to a voice signal, that is, in frequency division. Thus, it is not required for the peripheral station to amplify the plural carriers 1, 2 simultaneously. Thus, the transmitter is not necessary to be of high output type and miniaturization is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a wireless communication system consisting of a central station and a plurality of peripheral stations connected to the central station via wireless lines, and particularly relates to and wireless transmission technology for audio signals.

(Prior Art) The wireless communication system to which the present invention is directed is a wireless communication system that realizes connections between a host computer and a large number of data terminals via wireless lines, and also enables connections between audio terminals via wireless lines. type wireless network. That is, a wireless communication system is composed of a central station and a plurality of peripheral stations, with a host computer and a voice terminal connected to the central station, and a data terminal and a voice terminal connected to the peripheral stations.

An example of this type of wireless communication system is a satellite communication system.

Next, in the conventional transmission method for wirelessly transmitting data signals and audio signals, for example, as shown in FIG.
It is a two-wave transmission system using carrier waves 1 and 2 of carrier waves (x, f2). That is, data signals are transmitted, for example, by carrier wave 1 having frequency f1, and sound and voice signals are transmitted by carrier wave 2 having frequency 2.

The transmission and reception of data signals is performed as follows. First, when transmitting from the central station to peripheral stations, the central station broadcasts the packet-multiplexed data signal to each peripheral station in broadcast mode. The station selectively receives the data signal addressed to itself.

On the other hand, when transmitting from the peripheral stations to the central station, since each peripheral station shares the same line (carrier wave 1), the transmission is performed by time division multiplexing as shown in FIG. 4(b). That is, every time each peripheral station receives packet data from a data terminal, it converts the packet data into an intermittent burst signal and sends it to the wireless line. At that time, each peripheral station performs transmission operations using a scheduling method that predetermines transmission timing to prevent collisions, or a method that assumes a collision will occur and retransmits after a random period of time (slotted Aloha method). It is designed to do this.

On the other hand, voice communication between the central station and peripheral stations, or between peripheral stations, is performed using carrier wave 2 simultaneously with the transmission and reception of data signals, as shown in FIG. 4(b).

(Problems to be Solved by the Invention) By the way, in the conventional transmission system described above, since the peripheral station always sends out two carrier waves, the transmitter of the peripheral station needs to amplify the two waves simultaneously.

However, when a plurality of carrier waves are amplified simultaneously, it is necessary to use the operating point of the transmitter lower than the maximum output in order to suppress cross-modulation, that is, it is necessary to provide sufficient back-off. Therefore, it is necessary for the peripheral stations to be equipped with transmitters with higher output than the actual transmission output.

Providing a high-power transmitter increases the cost of peripheral stations, so in a star network like the one described above with a large number of peripheral stations, the cost of the large number of peripheral stations increases the cost of the entire network. The proportion increases,
This poses a problem from the economic standpoint of the entire network.

In order to solve this problem, it is sufficient to eliminate the need for peripheral stations to simultaneously amplify multiple carrier waves. In other words, the audio signal is also compressed on the time axis by speed conversion using TDMA.
(time division multiplexing), a method of bursting the data, treating it in the same way as packet data, and transmitting the audio signal and data signal on the same carrier wave (f) as shown in FIG. 5 can be considered.

However, when transmitting audio signals, in order to minimize transmission delays, it is necessary to avoid collisions and transmit them preferentially, and the ratio of audio signals to the line capacity is large (for example, in satellite networks, , the line capacity is usually around 56kbps due to the limitations of the transmission output of peripheral stations, whereas for audio signal transmission, ADPCM (
Adaptive Pulse CodeModula
tion) method has a bandwidth of 32 kbps, MPC<
16 in the Multi-Pulse Coding) method
(kbps bandwidth is required), while transmitting voice signals, the time slot in which other peripheral stations can transmit packet data to the carrier wave in time division is compressed, and the line capacity to accommodate the packet data is reduced. The problem arises that it is extremely limited.

The present invention was made in view of these problems, and its purpose is to transmit audio signals without affecting the line capacity for data signals and without requiring higher transmission output from peripheral stations. An object of the present invention is to provide a wireless communication system that enables simultaneous transmission and reception.

(Means for Solving the Problems) In order to achieve the above object, the wireless communication system of the present invention has the following configuration.

That is, the wireless communication system of the present invention includes a central station and a plurality of peripheral stations connected to the central station via wireless lines, and performs wireless communication in which data signals and voice signals are transmitted and received using carrier waves of different frequencies. In the system; the peripheral station includes a speed converting means for converting the audio signal into bursts by a speed converting operation; a modulating means for modulating carrier waves of different frequencies with the packetized data signal and the burst audio signal; and a voice signal. The present invention is characterized by comprising: a transmission control means for wirelessly transmitting a modulated carrier wave for a signal and a modulated carrier wave for a data signal by switching them so that they do not overlap in time.

(Operation) Next, the operation of the wireless communication system of the present invention configured as described above will be explained.

When transmitting data signals and audio signals from peripheral stations to the central station simultaneously, the peripheral stations transmit the data signals and audio signals using separate carrier waves. This is the same as before, but in the present invention, at any given point in time, the peripheral station switches to transmit only one wave, either the modulated carrier wave for the data signal or the modulated carrier wave for the voice signal. , that is, it is transmitted by so-called frequency time division.

As a result, since there is no need to simultaneously amplify multiple carrier waves at the peripheral station, the transmitter does not need to be of a high-output type and can be made smaller and lower in price. Furthermore, since the audio signal and the data signal are transmitted and received using two carrier waves, the transmission of the audio signal does not affect the line capacity for the data signal.

Regarding transmission from the central station to the peripheral stations, even if the peripheral stations receive two waves at the same time, the size of the high-frequency circuit of the reception system of the peripheral stations is not affected, so the peripheral stations receive two waves as before. will be received at the same time.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

The peripheral stations in the wireless communication system according to the present invention are configured, for example, as shown in FIG. 1, and the central station is configured, for example, as shown in FIG.
It is configured as shown in the figure.

In the peripheral stations shown in Figure 1, starting from the common parts,
1 is an antenna, 2 is a high-frequency circuit, and the high-frequency circuit 2 is specifically composed of a solid-state amplifier for transmission and a low-noise converter for reception.Normally, the antenna 1 and the high-frequency circuit 2 are installed as an outdoor device. There is. Further, 3 is a multiplexer (MPX), and this MPX 3 switches and outputs the transmission system signal from the switch 12 to the high frequency circuit 2 and the reception system signal from the high frequency circuit 2 to the down converter 4.

Next, the received signal (data signal) sent out by the MPX 3, which indicates the route for handling the packetized data signal, is frequency/wave frequency converted by the down converter 4, and then enters the demodulator 6 via the hybrid 5.

The demodulator 6 demodulates packet data, and a part of the signal in the demodulation process is sent to the timing control section 7, and the demodulated packet data is sent to the data control section 8. Since a timing signal is multiplexed in the received data signal, the timing control unit 7 receives a part of the signal from the demodulator 6, extracts the timing signal from it, and creates a transmission frame (TD) based on the timing signal.
It generates various timing signals such as a frame timing signal for the MA frame, a slot timing signal indicating a burst break, and a transmission timing signal for switching data and audio signals, and sends them to the data control unit 8, switch 12, and compression buffer 16. supply timing signals. Then, the data control unit 8 selects packet data addressed to its own station from among the packet data input from the demodulator 6, performs protocol conversion on it, and transmits the data via the line interface 9 to a data terminal overseas.

On the other hand, packet data sent by data terminals outside the ward is
The modulator 1 is converted into a burst signal in the data control section 8 via the line interface 9 and synchronized with the timing signal supplied from the timing control section 7.
The data signal is sent to 0 and subjected to modulation processing here, is frequency-converted to a high frequency band by an up converter 11, inputted to MPX 3 via a switching device 12, and sent from an antenna 1 via a high frequency circuit 2 to a wireless line. be done. Here, the radio line through which the data signal is sent has a frequency f!, as shown in FIG. carrier wave 1 is used, and each peripheral station uses TDM
The data signal is sent out at a predetermined time position of the A frame.

Next, the signal converter 13, which indicates the route for handling voice signals, detects the presence or absence of a call (for example, on-hook or off-hook of the telephone) from a voice terminal (telephone, etc.) and converts it into a corresponding control signal. A codec (C0DIIC:C0DER/DECODER) 1 converts the voice signal into the common control line control unit 14 and inputs the voice signal after the call is generated.
Tell 5.

The common control line control unit 14 sends the input control signal to the data control unit 8. Then, the control signal is sent out to the data signal radio line from the above-mentioned route and transmitted to the central station. The central station performs frequency allocation control when the content of the control signal indicates the occurrence of a call, and performs line release control when the content of the control signal indicates the termination of a call.

The voice carrier frequency allocation signal issued by the central office that received the call is input to the data control unit 8 via the data signal reception route described above, and is transmitted to the common control line control unit 14. The common control line control unit 14 sets the frequency (for example, frequency fz) in the modulator 17 and demodulator 19 according to the assignment contents. In other words, the audio signal transmission method is SCP C (Single Channel).
It is based on the 1 Per Carrier system.

In this way, the frequency is assigned and the voice terminal becomes ready for communication.After that, the input voice signal from the voice terminal is band-compressed by the codec 15 via the signal converter 13, speed-converted by the compression buffer 16, and burst. be converted into That is, the compression buffer 16 constitutes speed conversion means. The burst audio signal is input to the switch 12 via a modulator 17 and an up-converter 18. The switch 12 switches the output of the up-converter 11 (modulated carrier wave related to the data signal) and the output of the up-converter 18 (modulated carrier wave related to the audio signal) so that they do not overlap with each other in time according to the timing signal from the timing control unit 7. and send it to MPX3 in order. 1. For example, as shown in FIG. 3, the audio signal uses carrier wave 2 of frequency f2,
A voice signal is transmitted in the first half of a TDMA frame, and a data signal is transmitted in the second half (frequency time division method). Thus, the modulators 10 and 17 transmit packetized data signals and bursted voice signals. It constitutes a modulation means for modulating carrier waves 1 and 2 of different frequencies (fl, f2) with signals, and also includes a timing control section 7 and a switching device 1.
2 constitutes a transmission control means as a whole.

On the other hand, the received signal (audio signal) sent out by the MPX3 is sent to the demodulator 19 via the down converter 4 and the hybrid 5.
The signal is demodulated and sent to an audio terminal (not shown) via the codec 15 and signal converter 13.

Next, in the central station shown in FIG. 2, the common section is composed of an antenna 21, a transmitting/receiving circuit 22, and a combining/separating circuit 23. In addition, the route that handles data signals is the modem (2
4-1 to 24-N) and data control unit (25-1 to 25-N)
N) and line interfaces (26-1 to 26-N).

On the other hand, the route that handles audio signals is the modem (27-1 to 27-2).
7-M), expansion buffers (28-1 to 28-M), codecs (29-1 to 29-M), and signal converters (30-1
~30-M>.

Then, the DAMA control device (Demand Assig.
c+ment Controller) 31 is responsible for allocating a carrier frequency when a call is generated and releasing the assigned frequency when the call is terminated.The network control device 32 is responsible for managing the entire data signal transmission system, and is responsible for data control. Section (25-1 to 25-N)
In addition to mainly performing overall control of the
The assignment signal from the A control device 31 is sent to the data signal wireless line.

(Effects of the Invention) As explained above, according to the wireless communication system of the present invention, a peripheral station that transmits a data signal and an audio signal simultaneously converts the audio signal into bursts and transmits the data signal and the audio signal. Since the transmission is frequency-divided, the transmitters of peripheral stations do not need to amplify multiple carrier waves simultaneously.
It does not need to be a high-output type, and can be made smaller and lower in price. Furthermore, since the audio signal and the data signal are transmitted and received using two carrier waves, there is an effect that the transmission of the audio signal does not affect the line capacity for the data signal.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the configuration of the peripheral station of the present invention, Fig. 2 is a block diagram of the configuration of the central station of the present invention, Fig. 3 is a time chart of the transmission system of the present invention, and Fig. 4 is the conventional transmission method. The spectrum of the method ((a) in the same figure) and the time chart (((a) in the same figure)
FIG. 5, which is a diagram showing b)), is a time chart when a single wave transmission method is used. 1... Antenna, 2... High frequency circuit, 3... Multiplexer (MPX), 4...
...Down converter, 5...Hybrid (H), 6...Demodulator, 7...
timing control section, 8... data control section,
9...Line interface, 10...
...Modulator, 11...Upconverter,
13... Signal converter, 14... Common control line control unit, 15... Codec (C0DEC:C0DER/DHCODI!R),
16... Compression buffer, 17... Modulator, 18... Up converter, 21.
...Antenna, 22...Transmission/reception circuit,
23...Synthesis separation circuit, 24-1 to 24-
N...Modulator/demodulator, 25-1 to 25-N...
...Data control section, 26-1 to 26-N...
・Line interface, 27-1 to 27-M...
...modulator/demodulator, 28-1 to 28-M... decompression buffer, 29-1 to 29-M... codec (CODEC: C0DER/DIICODER),
30-1 to 30-M... Signal converter, 31...
...DAMA control device, 32...Network control device. Agent Patent Attorney Yoshihiro Hachiman

Claims (1)

[Claims] In a wireless communication system consisting of a central station and a plurality of peripheral stations connected to the central station via wireless lines, the peripheral stations transmit and receive data signals and voice signals using carrier waves of different frequencies; speed converting means for converting the signal into bursts by a speed converting operation; modulating means for modulating carrier waves of different frequencies with the packetized data signal and the burst audio signal; A wireless communication system comprising: a transmission control means for wirelessly transmitting by switching such modulated carrier waves so that they do not temporally overlap with each other.