JPS6340502B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a time division multiple access device used in a time division multiple access communication system in which a plurality of earth stations share one communication satellite in a time division manner and communicate with each other. It is. More specifically, the present invention relates to a time division multiple access device to which a calling terminal is connected and a time division multiple access device to which a terminating terminal is connected in a demand assignment time division multiple access communication system that communicates with each other.

Conventionally, in time division multiple access communication systems for broadcast communication, a time slot corresponding to the speed of transmitting information from a transmitting terminal performing broadcast communication and a time slot of the same size as this time slot are assigned to each receiving terminal. It was common practice to set up a so-called transparent line by assigning a line to a call terminal, transmitting response information in the reverse direction from the receiving terminal to the calling terminal, and not processing the response information itself from each receiving terminal.

In this conventional method, in order to transmit the response information from each terminating terminal to the originating terminal, the satellite line requires a capacity equal to the information transmission rate of the originating terminal and equal to the total number of originating and terminating terminals. However, in general, the amount of response information from the terminating terminal to the originating terminal is less than 1/1000 of the forward information signal from the originating terminal to the terminating terminal, and each terminating terminal has a time slot of the same size as the forward information signal. Allocation for each response information from a satellite originally has the disadvantage that it is not suitable for a demand assignment time division multiple access communication system whose purpose is to use satellite lines efficiently.

This invention provides a demand assignment time division multiple access device with a function of extracting and accumulating significant response information from a transmission signal from a receiving terminal, and a function of extracting and accumulating significant response information from a transmission signal from a receiving terminal, and a function of extracting and storing significant response information from a transmission signal from a receiving terminal. 1/S of the number of lots (S is the maximum number of receiving terminals)
It is characterized by having a function of allocating the number of time slots, and its purpose is to make effective use of the satellite link.

Embodiments according to the present invention will be described below with reference to the drawings. FIG. 1 is an example of a time-division frame structure suitable for an embodiment of the present invention. RN ₁ ～
N _n is the synchronization burst to maintain synchronization,
D ₁ to _{D e} indicate time slots in which data bursts carrying information signals are arranged, and these time slots are divided into time slot lengths and per frame period according to the information rate for each communication terminal in response to the occurrence of a call. A number of time slots is assigned. Data bursts are transmitted using allocated time slots, and such allocation is done dynamically as calls occur.

FIG. 2 shows only the time slots set for broadcast communication as an embodiment of the invention. T is a time slot allocated for transmitting information from a calling terminal to a receiving terminal. Further, T ₁ to T _S are time slots of the same size each having a size of 1/S of the above-mentioned transmission time slot T, and are time slots assigned for transmitting response information from a receiving terminal. Further, the sum T' of T ₁ to T _S is equal to the transmission time slot T assigned to the originating terminal. S is the maximum number of called terminals.

FIG. 3 shows a circuit that functions to transmit response information from a called terminal in one of the time slots T ₁ to T _S for response information in FIG. 2, which are assigned. The decompression buffer circuit 1 is used to receive a burst (T)a transmitted from a transmitting terminal via a satellite line and convert it into a continuous signal b that can be received by a receiving terminal 2. When the receiving terminal 2 that receives the broadcast information receives the broadcast information b,
The response information is sent as signal c at the same rate as the outgoing information rate. Synchronization detection circuit 3, expansion buffer circuit 4
The readout control circuit 5 (or 7) is a circuit specifically added to realize the present invention. In the synchronization detection circuit 3, only significant information is detected from the reverse direction signal c from the receiving terminal 2 by flag synchronization or the like, and the detected signal d is transmitted to the buffer circuit 4. The buffer circuit 4 inputs F bits and S bits to the signal d.
At the same time, a bit is added to the signal and converted into a signal e having a transmission rate of 1/S of the broadcast information signal rate from the transmitting terminal.
The read control circuit 5 is a circuit that controls the read timing of the signal e from the buffer circuit 4,
This circuit also synchronizes the read timing of the compression buffer circuit 6 and the write end timing of the expansion buffer circuit 4 so that the response information from the terminal 2 is terminated within the assigned slot within one time division frame. The control circuit 7 is a circuit having basically the same function as the control circuit 5, and is for starting transmission to the assigned slot after all the signals d have been written into the compression buffer circuit 6. Either one of the circuits 7 is required. The control circuits 5 and 7 are given transmission frame timing,
The response signal is operated in synchronization with this so that the response signal is completed within one time slot.

The above operation is possible if the following relationship holds between the number of bits I _B of the response information c from the receiving terminal 2, the transmission speed BR _e of the signal e, and the read period T _fi of the relevant time slot on the time division frame. , and this condition generally holds true.

I _B /BR _e <T _f The compression buffer circuit 6 converts the signal e into a burst signal within a designated time slot (one time slot from T ₁ to _{T S} in FIG. 2).

The above explanation focused only on significant information as a response signal from the receiving terminal, but when transmitting a connection information signal for making/disconnecting a call, etc. using the same time slot, the input of the compression buffer circuit 6 It is necessary to combine the connection information and the signal, and to transmit only this connection information signal continuously at the allocated transmission rate (1/S of the broadcast information rate).

FIG. 4 shows a circuit for receiving response information from a plurality of receiving terminals sent in time slots T ₁ to T _S in FIG. 2 on the calling side. The transmitting terminal 8 compresses continuous broadcast information shown as a signal g into a burst h using a compression buffer circuit 9 and transmits it in a time slot T. The response signals i ₁ to i _s from the receiving terminal are received by decompression buffer circuits 10 ₁ to 10 _S , and the contents of these circuits 10 ₁ to 10 _S are sequentially read out at the same speed as the broadcast information transmission rate, and the signals j ₁ to j _S is time-division multiplexed and transmitted to the originating terminal 8 as a signal k. Since the response information from the terminating terminal ends within the time slot, the signal k is continuous, but the originating terminal 8 can correctly identify the response from each terminating terminal by the address of each terminal. In addition, if connection information signals such as call origination/disconnection are multiplexed with response information from each incoming terminal, circuits 10 ₁ to 10
_10S , a circuit is required to separate the connection information signal.

In the figure, the expansion buffer circuits 10 ₁ to 10 _S are shown separately for ease of understanding, but in reality, the slots T ₁ to T _S are sequentially received as shown in FIG. Similarly to the buffer circuit 1, the buffer circuit 1 operates at the same speed as the compression buffer circuit 9.
Two decompression buffer circuits may be used.

In reality, one multiple access device has the functions shown in Figures 3 and 4.
The configuration shown in the figure is provided, and a terminal connected thereto becomes a receiving terminal, but depending on whether it becomes a calling terminal, it operates as explained with reference to FIG. 3 or 4.

As explained above, by allocating a time slot of 1/S of the transmission broadcast information speed as a satellite line in the opposite direction used for transmitting response information from a receiving terminal with a substantially small amount of information, one-to-multiple It is possible to configure a full-duplex line between terminals and perform broadcast communication, increasing the utilization efficiency of the satellite line.

In particular, a demand assignment time division multiple access communication system that uses a common time division frame and allocates a number of time slots according to the communication speed for various information signals with different communication speeds uses a relatively simple circuit. A great advantage of this invention is that the above effects can be brought about simply by adding it to each earth station. In this invention, the time slot T for transmission from the originating terminal to the terminating terminal and the sum of time slots for response information from multiple terminating terminals to the originating terminal T'+=T ₁ +T ₂ +...+T _S are set equal. Therefore, the broadcast center is the same as one-to-one communication (one line for sending and one line for receiving at the same speed).
The TDMA interface becomes usable, and special processing such as extracting only significant information from the response line of each terminal in the TDMA device connected to the broadcasting center and sending it to the broadcasting center becomes unnecessary. Can be done.

Although the concept of this invention has the greatest effect in the embodiment described in the specification, it is not limited thereto, for example, in one-to-one peer communication, which is a special case of broadcast communication. A similar effect can be achieved in

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the configuration of a time division frame suitable for an embodiment of the present invention, FIG. FIG. 4 is a block diagram showing the configuration necessary for the operation when a receiving terminal for receiving broadcast information is connected to the connecting device according to the invention, and FIG. FIG. 3 is a diagram illustrating an example of a configuration necessary for operation. 2: Incoming terminal, 3: Synchronization detection circuit for detecting a significant signal, 4: Decompression buffer circuit, 5: Readout control circuit, 8: Outgoing terminal.

Claims (1)

[Claims] 1. Demand assignment time division multiplexing in which a plurality of earth stations share one satellite repeater in a time division manner, and time slots within a time division frame are assigned in response to a line setting request from a communication terminal. In a time division multiple access device that constitutes a connection communication system and is equipped with a line control means that varies the number of time slots to be allocated according to the information transmission speed of the terminal that requests line setup, When performing broadcast communication to a receiving terminal, when connected to a calling terminal, the number of time slots according to the speed of the calling terminal is allocated as transmission/reception lines, and when connected to a receiving terminal, the number of time slots corresponding to the speed of the calling terminal (up to S (below) A means for allocating the number of time slots corresponding to low-speed signals of 1/S of the speed as 1/S of the time slots for the receiving line of the originating terminal in the time division frame, and a means for allocating the number of time slots corresponding to the low-speed signal of 1/S of the speed as 1/S of the time slot for the receiving line of the originating terminal, and when the receiving terminal is connected, A means for extracting and storing only significant information from a response line of a terminal and transmitting it onto a satellite line so that the significant information from the terminal ends within the allocated time slot, and when the above-mentioned transmitting terminal is connected. Means for extracting only significant information from the low-speed signals from each of the above-mentioned incoming terminals and converting it to the same speed as the terminal speed of the above-mentioned outgoing terminal; A time division multiple access device having means for reading data and transmitting it to a calling terminal in the same way as in one-to-one communication.