JPH08316921A - Code transmission method - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the efficiency of use of transmission codes. When an error is detected on the receiving side, in the transmission method in which a specific detection pattern is output instead of the frame and a retransmission request is issued, the input signal is converted into an information source coding unit 22.
To 10-bit code, input the code sequence to the code inversion processing unit 25, and if it does not match the detection pattern (FIG. 1B), the code sequence is used as it is and is transmitted with an error detection code. When the coded sequence matches the detection pattern (FIG. 1E), the least significant bit of the error sensitivity in the coded sequence is inverted (FIG. 1F), and the error detection code is added to this bit for transmission.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention adds an error detection code to an input code sequence to form a frame, transmits it in frame units, and when a code error is detected on the receiving side, it is specified instead of the received code string. The present invention relates to a code transmission method for outputting a code sequence of.

[0002]

2. Description of the Related Art A code error or frame loss may occur in a transmission line or a storage system, an error is detected during reception / reproduction, and when an error is detected, a reception / reproduction code sequence has a specific code. There are transmission / accumulation systems that are replaced by sequences (detection patterns). In such a system, replacement with a specific code sequence (detection pattern) may not be performed when an error is detected.

FIG. 2 shows a conventional code transmission method of this type. On the transmitting side, as shown in FIG. 2A, the input terminal 11
The input code sequence from is supplied to the transmission frame construction unit 12 and is also input to the error detection coding unit 13 to create an error detection code, and the transmission frame construction unit 12 forms an input code string into frames, and each of the frames A corresponding error detection code is attached to each frame and supplied as a transmission frame to the transmission line 14 such as a wireless communication line. On the receiving side, FIG.
As shown in B, each received transmission frame transmitted from the input terminal 15 is separated into an error detection code and each code sequence by the reception frame division unit 16, and the former and the latter are supplied to the error detection decoding unit 17. The received code sequence that has been subjected to the code error detection and separated is output as it is to the output terminal 18 as an output code sequence, and is decoded although not shown in the figure.
The error detection code separated during this decoding may be used.

On the other hand, in the same transmission system, when an error is detected by the error detecting / decoding section 17 as shown in FIG. 2C, a detection pattern is generated from the terminal 19a to which the received code sequence separated from the switch 19 is supplied. Switching to the terminal 19b to which the detection pattern is supplied from the unit 21, the detection pattern is sent to the output terminal 18 in place of the code sequence of the error transmission frame.

As described above, although the same transmission system is used, two transmission modes are prepared. In the first mode, as shown in FIG. 2B, the reception code sequence is directly output regardless of the presence or absence of transmission error. Therefore, it is suitable for voice coded transmission, etc., in which a slight data error is allowed, and in the second mode, as shown in FIG.
When there is a transmission error in the frame as shown in C, the received code sequence is replaced with a specific code sequence (detection pattern), the detection pattern is used as the output code sequence, and a 1-bit error cannot be tolerated. If there is an error, it may be suitable for data transmission such as retransmission. Hereinafter, the first mode will be referred to as a voice transmission mode, and the second mode will be referred to as a data transmission mode.

A feature of the data transmission mode is that for a frame whose input code sequence differs from the detection pattern, it can be recognized by looking at the output code sequence that there is no transmission error in the frame. However, for example, if a system that requests the transmission side to retransmit when a detection pattern is detected on the receiving side has a frame that is the same as the detection pattern in the input code sequence, an error occurs for that frame. There is a problem that the retransmission request is continuously issued regardless of the presence or absence. In order to avoid this erroneous detection, conventionally, a specific 1 bit of a transmission code sequence forming a frame is always set to be different from the relevant bit of a detection pattern, and other bits are used for encoding an information source. There is a way.

FIG. 3A shows a structure for generating an input code sequence to which this conventional method is applied. It is assumed that the transmission code sequence of one frame is composed of N = 10 bits and the detection pattern is all zero {0, 0, 0, ..., 0} as shown in FIG. 3B. The input signal is N-1 = 9 in the information source coding unit 22.
Bit sign (FIG. 3C) {x (1), x (2), x
(3), ..., X (9)}, and the 1-bit check code in the check code adding section 23 is added to this code. For example, as shown in FIG. 3C, when the source coded sequence is packed in the 1st bit to the 9th bit of the transmission frame, the 10th bit is the 10th bit of the detection pattern as shown in FIG. 3D. "1" is padded so as not to match with. That is, the input code sequence is shown in FIG.
As shown in {x (1), x (2), x (3), ..., x
(9), 1}. By this method, for example, even if the source coded sequence is composed of all 0s, {0, 0, 0,
..., 0, 1}, and no erroneous detection occurs when there is no transmission error.

[0008]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As shown in FIG.
In the same transmission system, the voice transmission mode and the data transmission mode may be selectively used, and when the transmission frame of the transmission system has an N-bit configuration, 2 ^{N in the} voice transmission mode.
As a result, 1024 kinds of information can be transmitted when N = 10. However, in the data transmission mode, one bit in the transmission code of one transmission frame is used as a check code for distinguishing whether the frame is an information source coding sequence (input code sequence) or a detection pattern. , Part 1
Bits cannot be used for source coding. That is, if one transmission frame has N bits, there are 2 ^(N-1) kinds of information that can be expressed, and 1/2 of the information that can be expressed in that frame is ^N , and N = 10. Two
There is a problem that only ⁹ = 512 kinds of information can be expressed, and the use efficiency of the transmission code sequence is poor.

An object of the present invention is to provide a code transmission method which solves the poor utilization efficiency of the transmission code due to the addition of the check code in order to avoid erroneous detection, which was in the conventional method.

[0010]

In order to achieve the above object, according to the present invention, information source coding using all transmission bit numbers is performed on the transmitting side, and the information source coding sequence matches the detection pattern. Only, invert at least one predetermined specific bit in the source coded sequence. This inversion bit is assumed to have a small error sensitivity in the code sequence.
In other words, this reversal forces an error, but
Select a bit that is less affected by the error, for example, select the least significant bit of encoding.

[0011]

With this configuration, the information source coding is performed with all combinations of the transmission code sequences other than the coded sequences that match the detection pattern, and the decrease in the utilization efficiency of the transmission code sequences can be minimized.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A shows an input code sequence generation unit on the transmission side in a transmission system to which an example of the method of the present invention is applied. The input (transmission) code sequence of one frame is composed of 10 bits, and the detection pattern is all zeros {0, 0, 0 as shown in FIG. 1B.
The case of 0, ..., 0} will be described as an example. The input signal is encoded by the information source encoding unit 22 with the number of bits of one transmission frame. That is, in this example, it is encoded into 10 bits.
This information source encoded output is, as shown in FIG. 1C, 10-bit data {x (1), x (2), x (3), ..., X (1
0)}. This code sequence is input to the code inversion processing unit 25, whether or not this information source coded sequence is equal to the detection pattern is checked, and if the input information source coded sequence is not equal to the detection pattern, the code inversion process is performed. No processing is added in the unit 25, and as shown in FIG. 1D, the information source coding sequence is directly input (transmission) code sequence as shown in FIG.
It is output to the inside input terminal 11. On the other hand, when the input information source coded sequence is equal to the detection pattern, that is, when it is {0,0,0, ..., 0} as shown in FIG. 1E, a specific 1-bit code in the information source coded sequence Inversion occurs.
The bit to be inverted is the bit having the smallest error sensitivity in the information source coded sequence, that is, the bit having the least influence when an error occurs. For example, if the bit with the smallest error sensitivity is the second bit, the code sequence after inversion becomes {0, 1, 0, ..., 0} as shown in FIG. 1F, and this is the input (transmission) code sequence. It is output to the input terminal 11. In the case of the method of the present embodiment, there are 2 ¹⁰ −1 = 1023 kinds of information that can be represented by the information source coding with the 10-bit transmission code, which is about twice that in the case of the conventional method.

In this way, the source coded sequence is {0, 0,
In the case of 0, ..., 0} (FIG. 1E), the second bit is inverted and transmitted, so when the receiving side receives this correctly, it is received as {0,1,0, ..., 0}. , This is not processed as a detection pattern and there is no risk of continuing to issue a retransmission request, but the encoded sequence for the original input signal is {0, 0, 0, ..., 0} (FIG. 1E). Since {0, 1, 0, ..., 0} (FIG. 1F) is processed as reception for the input signal, that is, correct decoding is not performed, but the bit inversion is performed for the one having a small influence. , It doesn't matter so much. That is, the source coded sequence is {0,0,0, ..., 0} (FIG. 1E).
, And {0, 1, 0, ..., 0} (FIG. 1F), if they are received correctly, their code sequences are the same {0, 1, 0 ,. } (FIG. 1F), the inversion bit is selected so that even if such a situation occurs, the problem does not occur so much.

In general, according to the method of the present invention, when one frame has N bits, the representable information is 2 ^N -1 which is almost twice as large as that of the conventional method. In addition, the amount of information including the detection pattern is the amount of information (2 ^N
This means that the transmission code can be used without waste. In the above, only one bit with the smallest bit error sensitivity is inverted to obtain the best coding quality when it matches the detection pattern. However, in the input (transmission) code sequence, the same source coded sequence as the detection pattern is used. Need only be subjected to the sign inversion process so that the error sensitivity of the inversion bit is not minimum, and the number of inversion bits is not particularly limited to one.

[0015]

As described above, according to the present invention,
A source code is performed using all the transmission bit numbers, and then a code obtained by inverting at least one bit at a specific position in the information source coded sequence only when the information source coded sequence matches the detection pattern. By using a sequence as an input (transmission) code sequence, the transmission code sequence can be used without waste.

[Brief description of drawings]

FIG. 1A is a block diagram showing a configuration of a portion that generates a coded sequence on a transmission side to which a code transmission method of the present invention is applied, B is a diagram showing an example of a detection pattern, and C is an information source different from the detection pattern. A diagram showing a coded sequence, D is a diagram showing an input (transmission) code sequence in that case, E is a diagram showing an information source coded sequence that matches a detection pattern, and F is an example of the code sequence subjected to the code inversion process. FIG.

2A is a block diagram showing a transmitting side of a transmission system to which the present invention is applied, B is a block diagram showing a configuration of a receiving side in a voice transmission mode, and C is a receiving side in a data transmission mode. It is a block diagram which shows a structure.

3A is a block diagram showing a code generation unit in a conventional code transmission method, B is a diagram showing an example of a detection pattern, C is a diagram showing an example of an information source coded sequence, and D is an example of a detection code. The figure, E is a figure which shows an input (transmission) code sequence.

Claims (2)

[Claims] 1. A transmission side adds an error detection code to an input code sequence to form a frame, and transmits in frame units. On the reception side, when no code error is detected in a received frame, In the code transmission method in which the received code sequence is directly used as the output code sequence, and when a code error is detected in the received frame, the code sequence to be transmitted is not the received code sequence but the specific code sequence as the output code sequence. When the code sequence matches the specific code sequence, a code sequence obtained by inverting at least one predetermined code in the code sequence is used as the input code sequence,
A code transmission method, wherein when the code sequence to be transmitted does not match the specific code sequence, the code sequence is used as it is as the input code sequence. 2. The code transmission method according to claim 1, wherein a code having a small error sensitivity in the code sequence is used as the code to be inverted.