JPS581582B2 - Line connection method in SSRA communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides SSRA (Spread Spectrum
PN (Random Access, hereinafter referred to as "SSRA") communication method is used to separate lines in the communication system.
Pseudo Noise (hereinafter referred to as "PN") that relies only on codes can be transmitted by superimposing multi-frequency signals.
Significantly increasing the number assigned to communication stations, synchronizing the phase or frequency switching time of the multifrequency signal with the PN frame, and transmitting it, the receiving side establishing frequency synchronization from the frequency information of the multifrequency signal, and This invention relates to a method that is useful for coarse frame synchronization adjustment of PN codes based on phase and frequency switching timing, and is useful for shortening initial connection time.

In the conventional number assignment system using only PN codes, it is impossible to assign PN codes to all the stations that can communicate.

For example, PN generated in an 11-stage feedback shift register
When there are 176 types of codes and 1000 communication stations, it is not possible to allocate only the types of PN codes, and this lack of number allocation was a drawback in the existing technology.

Furthermore, to establish synchronization, frequency synchronization and frame synchronization of the PN code are required. In the synchronous method, first, the local frequency on the receiving side is shifted slightly, and then one frame of the PN code is searched, and synchronization is established here. If this was not possible, the local oscillation frequency on the receiving side was further shifted, and then the PN code frame was passed around, which was repeated over and over again to establish the initial connection.

Therefore, there was a drawback that initial connection took time.

The present invention is characterized by significantly increasing number allocation by ANDing a combination of a PN code and a multi-frequency signal, and further shortening the initial connection time by using frequency and phase information of the multi-frequency signal, Its purpose is to contribute to the establishment of completely random communication lines in a short time, which is the most important advantage of the SSRA communication system.

Although various methods can be considered for configuring the multi-frequency signal, the simplest case of a two-frequency signal will be explained as an example.

If signals of frequencies f1 and f2 are alternately superimposed on the SSRA signal and transmitted, the combination of f0 and f2 is the station number, and the PN code corresponds to the number.

If five types of combinations of f1 and f2 are prepared, number allocation will be increased five times compared to the conventional method even if the same PN code is used.

That is, five stations using the same PN code are separated by station numbers f1 and f2, and a communication line can be set up without interference.

The time required for initial connection is shortened as follows.

A conventional SSRA that generates an SSRA signal as shown in FIG.
A device (transmitter) 1, a synthesizer 2 that generates signals of frequencies f1 and f2, a switch 5 that switches its output, and an SSR
an adder 7 that combines the A signal and signals of frequencies f1 and f2;
A transmission system consisting of the antenna 8 and the antenna 8 will be explained.

The output signal of synthesizer 2 is sent to the SSRA device (transmission section)
It is controlled to be phase synchronized with the frequency supplied from 1,
Signals of frequencies f1 and f2 as shown in FIG. 2 are obtained at terminals 3 and 4.

The frame start position of the PN code is defined as the time when the contents of the feedback shift register that generates the PN code are all 1.

The switch 5 is controlled by a switch control signal 6 to alternately select terminals 3 and 4 in synchronization with the frame start position of the code used in SSRA, and a signal as shown in FIG. 3 is output from the switch 5. be done.

The signal is sent to the SSRA device (transmission section) in the adder 7.
It is combined with the SSRA signal output from antenna 8.
It is transmitted superimposed on the SSRA signal.

As shown in FIG. 4, the receiving system includes a conventional SSRA device (receiving section) 19, a synthesizer 20, mixers 12, 1
3, adders 14, 16, phase shifter 15, frame detector 1
8. The system has an additional frequency controller 17 and the like.

The frequency obtained at the output terminals 10 and 11 of the synthesizer 20 is the local oscillator signal f1+fIF, which is higher by the IF frequency fIF.
and f2+fIF, f1 and f received by antenna 9
The signal No. 2 is beat down by mixers 12 and 13 and converted to an IF frequency of frequency fIF.

The adder 14 synthesizes the signal, converts it into a CW IF signal, performs AFC (automatic frequency control) operation in the frequency controller 17, controls the synthesizer 20 with the information, and outputs the correct frequency information to the S.
If it is supplied to the SRA device (receiving section) 19, the time for frequency synchronization can be significantly shortened.

On the other hand, one of the output signals of mixers 12 and 13 (the output of 12 in FIG. 4) is phase-shifted by π, and the adder 16
PSK (Phase Shift Key
ng) Supplied to the frame detection circuit 18 as an IF signal.

Since the frame start position of the PN code corresponds to the phase change point of PSK, the frame start position can be detected by detecting the change point.

By giving this information to the SSRA device (receiving unit) 19, the rough adjustment of the frame search is completed, so only fine adjustment is required, and the synchronization time of the PN code can be shortened compared to the conventional method.

As a result, there is no need to alternately repeat frequency shift and PN frame search as in the conventional system, and the initial connection time can be shortened.

Note that once synchronization is established and the initial connection is completed, synchronization can be maintained using the SSRA signal itself, so
A communication line is established without losing synchronization, and the object of the present invention is achieved.

Therefore, the multi-frequency signal device on the transmitting/receiving side added in the present invention is no longer necessary, and its operation is stopped.

Since a large number of combinations of multi-frequency signals can be created, a large number of numbers can be assigned accordingly.

Therefore, the number of communicable stations can be dramatically increased.

Furthermore, the time required to establish a line between arbitrary stations is significantly reduced.

Note that even if the same PN code is used, interference can be avoided because the probability that the phases of the PN codes match is very small.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional SSRA device (transmission unit) 1 to which the method of the present invention is added, and FIG. 2 is an output signal waveform diagram of a synthesizer 2. FIG. 3 is a waveform diagram of the output signal from the switch circuit 5 when the output signal of the synthesizer 2 is selected as a switch in synchronization with the PN frame. FIG. 4 is a block diagram in which the method of the present invention is added to the conventional SSRA device (receiving section) 19. 1...SSRA device (transmission section), 19...
... SSRA device (receiving section), 8, 9 ... antenna, 2, 20 ... synthesizer, 7, 14,
16... Adder, 12, 13... Mixer, 5... Switch, 15... Phase shifter, 17... Frequency control 18... Frame detector.

Claims (1)

[Claims] I In the SSRA communication system, on the transmitting side, the PN code is used as a number and the combination of multifrequency signals is used as the station number, and the phase change or frequency change time of the multifrequency signal is synchronized with the PN code frame and transmitted by superimposing it on the SSRA signal. By receiving the above multi-frequency signal, the receiving side establishes frequency synchronization at the same time as detecting the transmission addressed to its own station number, detects the PN frame position from the point of phase or frequency change, and uses that information to determine the SS
A line connection method in an SSRA communication method characterized by shortening synchronization time of an RA communication line.