JPS59161145A - Stuff controlling system - Google Patents

Abstract

PURPOSE:To improve a utilizing efficiency of a satellite communication without deteriorating a stuff detecting error rate by using the time slot for a stuff disignation code to a trasmission of an information code, in a satellite communication system for executing a time division multiplex communication. CONSTITUTION:When a stuff existence signal is inputted from a stuff request generating circuit 2, a stuff existence pattern A and a dummy code are inserted into a stuff designating code use time slot S and a variable code use time slot V, respectively. Between the following (n) frames, an information code C from an input terminal 104, and an output signal from a transmitting elastic buffer circuit 1 are inserted into the slot S and the slot V, respectively. After passing through said (n) frames, a stuff non-existence pattern B and an output signal from the circuit 1 are inserted into the slot S and the slot V, respectively. Also, the output signal from the circuit 1 is always inserted into a slot I, and a selecting circuit 3 executes such an operation and outputs the output signal from a terminal 105.

Description

Detailed Description of the Invention The present invention relates to a satellite communication system that performs time division multiplex communication (hereinafter referred to as TDMAh), in which a terrestrial digital signal tT]
:Relates to a stuff control method when connecting asynchronously to an IMA system. When performing an asynchronous connection using a stuffing control method in a TDMA device, as shown in FIG.
Time slot for information code! , time slots V for variable codes. Most of one frame is occupied by the information code time slot (a)I, and the variable code time slot)V
is usually 1 bit, time slot S for stuff specification code
A few bits are prepared. On the transmitting side, the clock phase of the terrestrial digital signal is monitored every frame to determine the presence or absence of stuffing, and if stuffing is present, a stuffed pattern At is placed in the stuffing specified code time slot, and a dummy code is placed in the variable code time slot V. Insert each.

In the case of no stuffing, a non-stuffing pattern B is inserted into the time slot S for the stuff designation code, and an information code is inserted into the time slot V for the variable code. An information code is always inserted into the information code time slot. On the receiving side, the contents of the variable code time slot v are restored to the original signal by removing the Chita ε-code and the stuff specification code from the contents of the stuff specification code time slot S. By the way, the stuff specification code is a code used to detect the presence or absence of stuff on the receiving side, and if it is detected incorrectly, it will cause the terrestrial digital signal to lose frame synchronization, resulting in a frontage line break until synchronization is restored. It is desirable that the detection probability is high. For this reason, a method is adopted in which the number of designated stuff codes is increased and majority decision is made. Particularly in satellite lines, in view of the line quality provided, it is often necessary to further increase the number of stuffing designation codes in order to suppress stuff detection errors to a sufficiently low level. On the other hand, the Star 7 designation code is an important code for staff synchronization, but since it generates wasted pulses in information code transmission, increasing it will directly lead to a decrease in the utilization efficiency of the satellite line, so increasing it unnecessarily. It is not possible. The conventional staff control method had the dilemma described above.

The purpose of the present invention is to solve these problems by using time slots for stuff specification codes (Q) to transmit information codes, thereby improving the utilization efficiency of satellite lines without deteriorating the staff detection error rate. This provides a staff control method that can be used in a variety of ways.

The present invention utilizes the properties of the staff described below. The staff is determined by the clock frequency of the terrestrial digital signal and the TDMA frame frequency.
There is no continuous staffing. In addition, the stuffing rate ρ, which is the ratio between the repetition period at the time when stuffing is possible and the average period at which stuffing is actually performed, takes a small value, for example, about 0.1 or less, in order to keep the destuffing jitter on the receiving side small. The TDMA frame frequency is determined as follows. In other words, once you have a staff, it will take about 10 staff to get the next staff.
Take a gap longer than the frame. The minimum value l of the frame interval at which this stuffing occurs is the reciprocal TM of the maximum value ρMAX of the stuffing rate obtained from the respective deviation values of the clock frequency of the terrestrial digital signal and the TDMA frame frequency.
IN is an integer smaller than nearest K<TMIN. To summarize the above, the following can be said. In other words, stuffing is never performed between the frames with stuffing and the next frame with stuffing that is predicted to be earlier (t'on-1). Conventionally, time slots for stuff designation codes (Q) have not been used for other information transmission because there is an extremely high risk of causing stuff detection errors on the receiving side. However, considering that stuffing will never occur in the (1-1) frame after stuffing as described above, stuffing detection for n frames after stuffing is prohibited, and the remaining (1-n-1) ) By inserting a stuffed turn Bt between frames, the n frames during which stuff detection is prohibited can be used for other information transmission. The value of n is determined by K as follows. In other words, the number of frames (fl-n-1) into which the non-stuffing pattern B is inserted is the number i of stuff detection prohibited frames.
Is it the same as υ? Since there is no staff detection error when the next staff is present, there is no staff detection error #).

5-1 In other words, n-n-1≧n Therefore, 1 for n≦ Since both υ and n are positive integers When i is an even number, n = 1 becomes.

Even if the first erroneous stuff detection is performed in a frame corresponding to n frames on the sending side and stuff detection is prohibited between the next n frames, as long as the relationship between n and the party satisfies the above conditions, the next The presence of staff should be detected correctly. Once it is detected correctly, it will be detected correctly thereafter, so in practical terms, the staff detection rate can be said to be exactly the same as that of the conventional method.

FIG. 2 shows an embodiment of the stuff control method according to the present invention.
FIG. 3A is a block diagram of the transmitting side, and FIG. 3B is a block diagram of the receiving side. First, FIG. 2(a) will be explained. The terrestrial digital signal is input from the input terminal 101, and the clock signal is input from the input terminal 102.
are input to the transmission elastic buffer circuit 1 and stuff request generation circuit 2, respectively. The star and rough request generation circuit 2 inputs the TDMA frame signal for transmission from the input terminal 103 to the input terminal 102.
The phase of the clock signal from is monitored every frame, and when the phase shift reaches a certain set value, a stuffing request signal is output to the selection circuit 3 and the first monostable multi-by-break circuit 4. The first monostable multivibrator circuit 4 is triggered by the next frame to which this stuffing request signal is input and holds it for n frames. On the other hand, the input signal input to the transmission elastic buffer circuit 1 is reread by the TDMA system clock and output to the selection circuit 3. The selection circuit 3 inputs the output signals of the stuff request generation circuit 2 and the first monostable multivibrator circuit 4 and performs the following operations.

First, when a stuffing signal is input from the stuffing request generation circuit 2, the stuffing code time slot SK stuffing button At-1 the variable code time slot v
, there are 11 dummy codes, and then, for the next n frames, there are 10 input terminals in the time slot S for the stuff designated code.
Information code Cf from 4, time slot v for variable code
The output signal from the transmission elastic buffer circuit 1 is inserted into. After n frames have passed, the output signal from the transmission elastic buffer circuit 1 is inserted into the non-stuffing pattern Bt-1 variable code time slot (V) in the stuff designation time slot S. The output signal from the transmission elastic buffer circuit 1 is always inserted into the information code time slot 1. The selection circuit 3 performs the above operations and outputs an output signal from the output terminal 105. Next, output terminal 1 in Fig. 2 (BL e will be explained. Fig. 3 +61)
The output signal from the stuff detection circuit 5. Reception elastic buffer circuit6. Second monostable multivibrator circuit7. It is input to each circuit of the data extraction circuit 8.

The stuff detection circuit 5 monitors the received signal and the TDMA frame signal received from the input terminal 107, and performs stuff detection by monitoring the time slot (St) for the stuff designation code in the received signal. When the presence of stuff is detected, a stuff detection signal is input to the second monostable multivibrator circuit 7 and the reception elastic buffer circuit 6. The second monostable! The Luna By Play 2 circuit 7 is triggered at the next frame in which the stuff is detected and is held for n frames.

This serves as a stuff detection prohibition signal and is input to the stuff detection circuit 5 and data extraction circuit 8. In the stuff detection circuit 5, this signal inhibits the detection of stuff between J) n frames. The receiving elastic buffer circuit 6 removes the dummy code in the variable code time slot V and the code in the stuff designated code time slot S by the stuff detection signal, and returns the signal to the original terrestrial digital signal and outputs it from the output terminal 109. . On the other hand, the data extraction circuit 8 extracts the information code C in the time slot 8 for the system stuff designation code in response to the stuff detection prohibition signal from the second monostable multivibrator circuit 7, and outputs it from the output terminal 108. FIG. 3 shows a timing diagram for explaining the operation of FIG. 2 (bl). FIG. bl is the frame number, and FIG. 3(c) is the contents of time slot 8 for stuff designation code.
9, C is an information code inserted into frame numbers 2 to 5. FIG. 3(d) is a stuff detection signal, which is an output signal of the stuff detection circuit 5 of FIG. 2(b). +61 in FIG. 3 is a stuff detection prohibition signal, which is the output signal of the second monostable multivibrator circuit 7 in FIG. 2(b). By operating as described above, it is possible to transmit other information codes C that are completely unrelated to stuff control using the stuff designation code time slot Sf.

As explained above, the time slot for the stuff designation code, which is traditionally an important code for staff synchronization but was considered a wasted pulse in terms of information transmission efficiency, can be used for information code transmission, which improves information transmission efficiency. It is possible to achieve both improvement and reduction of the stuff detection error rate at the same time.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the frame structure of the stuff control method, FIG. (a) to (el) are timing diagrams for explaining the operation of the embodiment in Fig. 2. In the figure, 1...transmission elastic buffer circuit, 2... staff Request generation circuit, 3...
... Selection circuit, 4 and 7 ... Monostable multivibrator circuit, 5 ... Stuff detection circuit, 6 ... Reception elastic buffer circuit, 8
...This is a data extraction circuit.箭 J Ward No.'z Map

Claims (1)

[Claims] In the stuffing control method that is used when one independent synchronous system is used as a transmission path to transmit digital signals of other independent synchronous systems, the stuffing that is prepared for each frame is used for the horizontal ratio of the presence or absence of stuffing on the receiving side. A stuffing control method characterized in that an information code other than a stuffing designation code is transmitted using a stuffing designation code time slot between n frames immediately after a designation of stuffing in a designated code time slot.