JPS62147828A - Data transmission system - Google Patents

Abstract

PURPOSE:To reproduce surely a data and to attain the data communication with high transmission efficiency without error by sending a data to be sent while switching low/high speed modulations via forming coding by an error detection code and blocking by plural frames. CONSTITUTION:After an input data from a transmission terminal equipment 1 is subject to error detection coding by a coder 2, the result is coded by using an error correction code. The coded data is modulated by a high speed modulator 3 and sent to the reception side, while a control signal from a control signal transmission 4 is modulated by a low speed modulator 5 by the instruction of a controller 8 and sent to the reception side. A low speed demodulator 12 at the reception side demodulates the control signal, which is received by a control signal receiver 13. When a data succeeding to the control signal exists, the demodulator is switched into a high speed demodulator 9 by the instruction of a controller 14 then the data is received. The received data is inputted to a decoder 10, where the data is decoded by using the error correction code, then the result is sent to a reception terminal equipment 11.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is particularly useful for high-speed data communication in extremely poor transmission paths such as phasing propagation paths, especially in communication of mobile devices such as car phones and mobile phones. This relates to data transmission methods.

(Prior Art) FIG. 6 shows a block diagram of a conventional data transmission system using error control coding. Here 1a is an encoder, 2
a is a modulator, 3a is a demodulator, 4a is a decoder, and 5a is a transmission path. The transmitted data is encoded by the encoder 1a
The frame consists of a control signal, data, a frame check, and a sequence as shown in the figure. This frame is modulated by the modulator 2a and transmitted to the communication channel 5. The signal from the communication path 5a is sent to the demodulator 3a.
The signal is demodulated by the decoder 4a and reproduced by the decoder 4a. If an error occurs in the communication path 5a, the existence of the error is detected by the decoder 4a according to the frame check sequence, and a retransmission request is sent to the transmitting side.If there is no error, a request to transmit the next frame is sent as a control signal. The information is transmitted to the transmitting side, and the transmitting side transmits the next data.

If an error occurs in the control signal, both the transmitter and the receiver wait for a control signal from the other party, and after a certain timeout, the control signal is retransmitted and communication continues.

(Problems to be Solved by the Invention) However, in a communication channel with extremely high error rates such as a fading propagation channel, there are many errors in the control signal, and the transmission efficiency becomes extremely poor because there is a large amount of time waiting for timeout. Additionally, there is a problem in that errors in control signals cannot be detected and communication cannot be continued.

It is an object of the present invention to provide a transmission system that reliably reproduces data without errors even in the fading propagation path as described above, and performs data communication with high transmission efficiency.

(Means for solving the problem) The present invention provides block numbers, the number of frames in one block,
The control signal including the block error correction code type and the block error correction code type is transmitted by low-speed modulation with few errors, and the transmitted shift data is
Framing, encoding each frame with an error detection code,
After blocking with multiple frames and encoding with an error correction code, the data is transmitted using high-speed modulation.
These low-speed and high-speed modulations are switched and transmitted.

(Function) According to the present invention, in a data communication device, the transmitting side frames data, encodes it with an error detection code, blocks it, and then transmits the data after a control signal. The blocked data is encoded with an error correction code. The error correction code is selected from a plurality of types including no code. The control signal includes the number of data frames, block number, type of error correction code, etc., and is encoded with an error detection code and then transmitted using a low-speed modulation method with a low error rate.

After receiving the control signal, the receiving side reads the number of frames, block number, type of error correction code, etc. from the control signal, and receives data. When encoded with an error correction code, the error correction code is decoded. The received data is decoded frame by frame using an error detection code, and the presence or absence of errors in each frame is detected. The presence or absence of an error p for each frame is communicated to the transmitting side as a control signal. This control signal is also encoded with an error detection code and then transmitted using a low-speed modulation method with a low error rate. If an erroneous frame exists, the transmitter retransmits the erroneous frame.

The retransmission method is the same as the transmission method described above, in which a control signal is modulated using a low-speed modulation method and then sent using a high-speed modulation method. If the number of error frames in a block exceeds a certain value, it is encoded with an error correction code and then sent. When there is no error frame or when one block of data has been sent without error due to retransmission, the transmitting side starts transmitting the next block.

If there is no data to transmit, only the control signal is sent.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the present invention,
1 is a transmitting terminal device that generates data to be transmitted; 2 is an encoder to be described later; 3 is a high-speed modulator; 4 is a block number;
A control signal transmitter that generates a control signal including the number of frames in one block and the type of error correction code; 5 a low-speed modulator that modulates the control signal in a method with fewer errors; 6 a control signal transmitter that generates a control signal from the receiving side; A low-speed demodulator that demodulates, 7 a control signal receiver that receives control signals from the low-speed demodulator 6, 8 a controller that performs switching control between high-speed modulation and low-speed modulation, retransmission control, etc., and 9 a communication channel. 1θ is a decoder to be described later, 1 is a data receiving terminal device, 12 is a low-speed demodulator for demodulating the control signal from the communication channel, 13 is a low-speed demodulator 12 14 is a controller that performs switching control between high-speed demodulation and low-speed demodulation and retransmission request control for frames in which an error is detected by the decoder 10; 15 is a controller that performs retransmission request control; a control signal transmitter for generating a control signal; 16 a low-speed modulator for modulating the control signal in a low-error manner; 17 and 1;
8 is a switch, and 19 to 22 are antennas.

As shown in FIG. 2, the encoder 2 in FIG. 1 includes a framer 4, an error detection encoder 42, a blocker 43,
and an error correction encoder 44 prepared with several error correction codes, frames the input data with an arbitrary frame length, encodes each frame with an error detection code, and encodes the encoded frames. The data is divided into blocks, and one block is encoded using an error correction code.

As shown in FIG. 3, the decoder 10 in FIG. 1 consists of an error correction decoder 5, a block detector 52, an error exposure decoder, and a frame detector 54, The signal demodulated by the unit 9 is decoded using an error correction code,
The presence or absence of errors is detected by decoding each frame with an error detection code.

Next, the operation will be explained. Referring again to FIG. 1, input data from the transmitting terminal device 1 is subjected to error detection encoding in the encoder 2, and then encoded using an error correction code. The error correction code is selected from a plurality of types. The encoded data is modulated by the high-speed modulator 3 and sent to the receiving side, but before data transmission, the control signal transmitter 4
A control signal is modulated by the low-speed modulator 5 and sent to the receiving side. The control signal includes the type of error correction code, data length, etc. When the sending side has no data to send, only the control signal is sent to the receiving side. On the receiving side, the control signal is demodulated by the low-speed demodulator 12 and received by the control signal receiver 13. If there is data following the control signal, the controller 14 instructs the high-speed demodulator 9 to switch to receive the data. At this time, the error correction code of the decoder 10 is also selected by the control 14. The received data is input to the decoder 1θ, decoded by an error correction code, and then decoded by an error detection code to detect the presence or absence of an error, and the detection result is sent to the controller 14. If no error is detected, the received data is sent to the receiving terminal device 11. The controller 14 sends a retransmission request or a request for next data as a control signal depending on the error detection result. A control signal is output from a control signal transmitter 15, modulated by a low-speed modulator 16, and sent to the transmitting side.

On the transmitting side, the control signal demodulated by the low-speed demodulator 6 is input to the control signal receiver 7, and the result is transmitted to the controller 8.

When the controller 8 receives a retransmission request, it retransmits the data. If there is no error, transmit the next data.

Figure 4 shows a low-speed modem 5 in a fading propagation path.
12 and high-speed modulators 3 and 9 are shown. The fading frequency is 40Hz.

The data rate of the low-speed modem 5, 12 is 300 bps.

The data rate of the high speed modem 3, 9 is 4800 bps. Low speed modem 5 at input power -90dBm,
The error rate of 12 is 1710 compared to high-speed modulators 3 and 9.
0, the error rate is low.

FIG. 5 is a block diagram showing another embodiment of the present invention;
High-speed modulator 3, 23, high-speed demodulator 9゜24, encoder 2
, 25, by providing decoders 10 and 26 on both sides, providing both sending and receiving terminal functions as sending and receiving terminal devices 27 and 28, and adding switching devices 29 and 30, two-way data communication is possible. can be made to do so.

(Effects of the Invention) As explained above, according to the present invention, in data communication, control signals are transmitted at low speed, data is transmitted at high speed, and erroneous data is retransmitted. Therefore, error-free data transmission can be performed with high efficiency even on a transmission path with a high error rate, such as a fading propagation path.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of the encoder shown in FIG. 1. Figure 3 is a block diagram of the decoder in Figure 1, Figure 4 is an explanatory diagram of the bit error rate, Figure 5 is a block diagram showing another embodiment of the present invention, Figures 6 and 7. is an explanatory diagram of the prior art. DESCRIPTION OF SYMBOLS 1... Transmission terminal device, 2... Encoder, 3... High speed modulator, 4... Control signal transmitter, 5... Low speed modulator, 6... Low speed demodulator, 7 ...control signal receiver, 8
...Controller, 9..High-speed demodulator, 10..Decoder, 1..-Receiving terminal device, 12..-Low-speed demodulator,
13... Control signal receiver, 14... Controller, 15.
...Control signal transmitter, 16...Low speed modulator. Patent applicant: Oki Electric Industry Co., Ltd. the law of nature! 2nd figure 1 ft tl 3 ℃ puff 1. Fufu Figure 3 He has 7 breasts and milk 16 Kurano no Wataru ■ Ko 3 Mkl Village's establishment report Figure 6 Hawk 2 Raimi Shit 4 City Ki's 7 S and Yome Koku Figure 7

Claims (1)

[Claims] a) Encoding means that frames data to be transmitted, encodes each frame with an error detection code, blocks a plurality of encoded frames, and encodes one block with an error correction code. b) control signal transmitting means for generating a control signal including a block number and the type of error correction code; c) high-speed modulation means for modulating the signal encoded by the encoding means; and e) the control. low-speed modulation means for modulating a signal in a method with few errors; h) low-speed demodulation means for demodulating the control signal from the communication path; i) decoding for decoding the data signal based on the outputs of these demodulation means and detecting the presence or absence of data errors. 1. A data transmission system characterized in that the data transmission system is provided with means and j) as a receiving means, and receives data from the communication path by switching between the high-speed modulation means and the low-speed modulation means.