JPS6056344B2 - Wireless communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a communication system in which a plurality of wireless stations connect, for example, in multiple ways over a wireless line, in particular, the line synchronization control time is short.
The present invention also relates to a data transmission method with high line utilization efficiency.

In FIG. 1 showing an example of a wireless communication system to which the present invention is applied, a wireless station 1 out of a plurality of (three in this case) wireless stations is shown.
Assume that a call to wireless station 2 occurs at .

In this type of system, a small number of radio channels are shared by each radio station for the purpose of effective use of frequencies, and radio stations that are not making calls do not use radio channels. Therefore, when a call occurs, an unused radio channel (hereinafter referred to as
It is called an empty channel. ) is captured and the connection operation is performed according to the time chart shown in FIG. Here, the wireless station 1 enters a calling operation, sends out a selective calling signal (Figure 2 a), and then the wireless station 2 returns a response signal (Figure 2 d).
T before the exchange of information signals (Fig. 2 c, f) begins.
-T. It takes time. That is, in FIG. 2, time T
The radio station 1 which has entered the calling state at O transmits a selective calling signal a specific to the radio station 2 to the transmission radio wave having the frequency f (FIG. 2b) and sends it to the radio station 2. This radio wave arrives at the radio station 2 at time Tl, and the radio station 2 receives the selective calling signal at the same time as opening the reception squelch e. If the signal is indeed the signal of the local station and the status of the local station is such that communication is possible, the response signal d is placed on the transmission radio wave g of frequency 10 and sent to the wireless station 1. Radio station 1 receives time T. When receiving a response signal from the radio station 2 from the radio wave that has arrived, the radio station 1 stops sending out the selective paging signal and at the same time sends out the communication information signal 1 shown in FIG. 2c. The wireless station 2 confirms that the selective calling signal has stopped at time α. The communication information signal 2 shown in FIG.
If this system becomes complicated, the line control also becomes complicated, the time T, -T required for line connection increases, and the line utilization efficiency decreases.

Especially in such a random access wireless system, the rise time T. -T, the dominant time is the time required for clock extraction and synchronization control such as frame synchronization. This clock extraction circuit is generally a bandpass filter whose center frequency is the clock frequency.
A clock signal is extracted from the subcarrier modulated by this filter. In this method, the time required for clock extraction is NT (N≧3, T is the period of the signal clock), and it is time consuming. An object of the present invention is to provide a wireless communication system that requires less time for line connection.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 3 is a diagram showing the configuration of wireless station 1, 2, or 3 in one embodiment of the present invention. In the figure, 11 is an antenna, 12 is an antenna duplexer, 13 is an output circuit, 14 is a main modulator, 15
is a main carrier source, 16 is a primary modulator, 17 is a subcarrier source,
18 is a terminal device (for example, a digital device such as a fax machine), 19 is a first detector, 20 is a second detector, 21
22 is a frequency converter, 23 is a synchronous regeneration circuit, 100 is a transmitter, and 200 is a receiver. The operation shown in FIG. 3 will be explained below using the time chart shown in FIG.

The output of the subcarrier source 17 (FIG. 4a) is transmitted to the frequency converter 2
For example, the frequency is divided by 2 and supplied to the terminal device 18. This frequency-divided output (FIG. 4b) matches the clock of the terminal device 18, and the terminal device 18 operates with this clock. The output of the subcarrier source 17 is also supplied to a subcarrier control circuit 21, and the control circuit 21 removes the subcarrier pulse at the rising edge of the lock signal (Fig. 4b), as shown in Fig. 4c, for example. Outputs a pulse train. The output of this control circuit 21 is supplied to the primary modulator 16, and is subjected to, for example, phase modulation (Fig. 4e) with the output signal of the terminal device 18 (Fig. 4d).
). The output of the primary modulator is, for example, amplitude-modulated on the output of the main carrier wave source 15 by the modulator 14, and then sent out from the antenna 11 via the output circuit 13 and the duplexer 12 as a radio carrier wave having a center frequency f1.

On the other hand, in exactly the same manner, the radio carrier wave transmitted from the radio station 2 at the center frequency F2 is detected by the first detector 19, and becomes a modulated subcarrier wave as shown in FIG. 4e. From this output.
A clock pulse (FIG. 4g) is obtained by the synchronous reproducing circuit 23. In other words, the synchronous reproducing circuit 23 includes a delay circuit 30 that delays the subcarrier by a time t as shown in FIG.
xclusive-NOR logic circuit 31, and the output of the delay circuit 30 (FIG. 4f) and the first detector 1
9 (FIG. 4e) is input to the circuit 31 to obtain FIG. 4g. With this method, the rise time that conventionally required several baseband clocks (NT, N = 5, 6, etc. Approximately T) a recovered clock can be obtained, making it possible to significantly shorten the rise time.
On the other hand, the second detector 20 performs phase detection on the modulated subcarrier by, for example, delay detection. The signal output is supplied to the terminal device 18 together with the above-mentioned re-output clock. Although the above description has been made regarding clock synchronization, the time required to detect a synchronization signal can be shortened by similarly placing information on subcarriers corresponding to bits regarding control of frame synchronization and the like.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a wireless system to which the wireless communication system of the present invention is applied, FIG. 2 is a time chart showing the connection operation when wireless station 1 makes a call and connects to wireless station 2, and FIG. 3 FIG. 4 is a time chart explaining the operation of a subcarrier logic processing circuit and a synchronization regeneration circuit for placing a synchronization signal on a subcarrier in correspondence with bits, and FIG.
The figure is a circuit diagram showing an example of a synchronous regeneration circuit. In the figure, 1 to 3 are radio stations, 11 is an antenna, 12 is an antenna duplexer, 13 is an output circuit, 14 is a main modulator, 15 is a main carrier source, 16 is a primary modulator, 17 is a subcarrier source, 1
8 is a terminal device, 19 is a first detector, 20 is a second detector,
21 is a subcarrier logic processing circuit, 22 is a frequency converter, 2
3 is a synchronous regeneration circuit, 30 is a delay circuit, 31 is a logic circuit,
100 is a transmitter, and 200 is a receiver.

Claims (1)

[Claims] 1. In a wireless data communication system in which a plurality of wireless stations mutually transmit and receive data using carrier waves, a transmitting unit of the wireless station transmits the carrier wave to 2 with a pulse train that is primary modulated with a data signal.
a modulator that performs subsequent modulation; and means for including a synchronization control signal in advance in a bit-corresponding manner to some of the bits of the pulse train, and the receiving section of the radio station receives a data signal modulated from a received modulated carrier wave. It is characterized by comprising means for detecting a pulse train, a circuit for reproducing the control signal using the output of the detecting means and a delayed output of the output, and means for detecting a data signal from the pulse train using the output of the reproducing circuit. Wireless communication method.