JP3189196B2 - Data transmission system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system for transmitting transmission data having different transmission speeds using the same transmission device having a constant transmission speed.

[0002]

2. Description of the Related Art In a conventional data transmission system for transmitting transmission data having different transmission speeds using the same transmission device having a constant transmission speed, a plurality of encoding circuits having different transmission efficiencies and respective encoding circuits are provided. By preparing a plurality of decoding circuits corresponding to in advance and selecting an encoding circuit and a decoding circuit suitable for the transmission rate of the transmission data, transmission data having different transmission rates can be transmitted using the same transmission apparatus. Was transmitting.

FIG. 7 shows an example of the configuration of such a conventional data transmission system. In this figure, ₁₁ and 1 ₂
Are the transmission efficiency (N / M) and (N '/ M'), respectively.
And a plurality of registers 2a, 2
, and registers 2b, 2b,... 3 ₁ and 3 ₂ are encoding circuit selector switch.
A transmission device 4 includes a transmitter 5 and a receiver 6, and always transmits transmission data at the same transmission speed. Also,
7 ₁ and 7 _2, the decoding circuit corresponding to the coding circuit 1 ₁ and 1 _2, respectively, 8 ₁ and 8 ₂ are decoding circuit selector switch.

Next, the operation of the data transmission system shown in FIG. 7 will be described. A transmission rate of the transmission data D ₀ to D _n to be transmitted is compared with the transmission rate of the transmitter 4, encoding circuit 1 ₁ and a decoding circuit 7 _first set having a transmission efficiency corresponding or coding circuit, 1 ₂ and decoding circuit 7 ₂
Set is selected, the encoding circuit switching switch 3 _1, 3 ₂ and decoding circuit switching switch _81, 82 is switched accordingly. As a result, the transmission data D ₀ to be transmitted
D _n is inputted through the coding circuit switching switch 3 ₁ coding circuit 1 _1, or 1 _2, after being encoded by input encoder, via an encoding circuit switching switch 3 ₂ The data is input to the transmission device 4. In the transmitter 4, which is input via the encoding circuit changeover switch 3 _2, after the transmission data encoded is transmitted by transmitter 5 and received by the receiver 6. Transmission data received by the receiver 6 through the decoding circuit switching switch ₈₁ are input to the decoding circuit 7 ₁ or 7 _2, the original transmission by decoding circuit input data D ₀ to D _n after being decoded, and output through the decoding circuit switching switch _82.

[0005]

By the way, in the above-mentioned conventional data transmission system, the coding circuits 11 ₁ ,
1 _2, for example, although it is possible to select a transmission efficiency of an integer ratio, such as 1 / 2,2 / 3, it is impossible to select a transmission efficiency which is not an integer ratio. For this reason, there is a defect that transmission data having an arbitrary transmission rate that does not conform to the above-described transmission efficiency cannot be transmitted.
Also, in the conventional data transmission system described above,
Before transmitting the transmission data D ₀ to D _n, the encoding circuit switching switch 3 _1, 3 ₂ and decoding circuit switching switch _81, 82
Need to be switched at the same time. However, usually
Encoding circuits 1 ₁ and 1 ₂ , encoding circuit changeover switches 3 ₁ and 3 ₂
Further, the transmitting side including the transmitter 5 and the receiving side including the receiver 6, the decoding circuits 7 ₁ and 7 _2, and the decoding circuit changeover switches 8 ₁ and 8 ₂ are installed at locations separated from each other. Thus, a switching signal for controlling the switching of the coding circuit switching switch 3 _1, 3 ₂ and decoding circuit switching switch _81, 82, the disadvantage that must be transmitted in a different transmission means from the transmitter 4 there were. Further, at the time of switching of the encoding circuit switching switch 3 _1, 3 ₂ and decoding circuit switching switch _81, 82, because the instantaneous interruption occurs, there is a problem that it is impossible to obtain a high channel quality.

The present invention has been made under such a background, and an object of the present invention is to provide a data transmission system capable of transmitting transmission data having an arbitrary transmission speed and obtaining high line quality.

[0007]

According to the present invention, there is provided a data transmission system for transmitting transmission data having different transmission speeds by using the same transmission device having a constant transmission speed. A transmission timing pulse output from a transmission device is compared, and when the generated timing pulse and the transmission timing pulse match, a first value is taken, and in other cases, timing information that takes a second value is generated. A timing information generating circuit that performs convolutional coding on the transmission data and the timing information to output a coded signal, and the transmission device, wherein the transmission device is configured to generate the coded signal based on the transmission timing. A transmitter for receiving and transmitting the encoded signal; and a receiver for forming the transmission device and receiving the transmitted encoded signal. A maximum likelihood decoding circuit that performs maximum likelihood decoding on the signal, and separates and outputs transmission data and timing information from the decoded signal; and a generation timing of the transmission data based on a timing at which the timing information takes a predetermined value. A timing generation circuit that extracts and outputs a pulse,
And a retiming circuit for retiming the transmission data using the extracted generated timing pulse.

[0008]

According to the above arrangement, the timing information generation circuit compares the generated timing pulse with the transmission timing pulse, and takes the first value if they match, and takes the second value otherwise. Generate timing information.
As a result, the encoding circuit convolutionally encodes the transmission data and the timing information together and outputs an encoded signal, so that the transmitter captures and transmits the encoded signal based on the transmission timing. On the other hand, when the receiver receives the encoded signal transmitted from the transmitter, the maximum likelihood decoding circuit performs maximum likelihood decoding on the encoded signal, and separates transmission data and timing information from the decoded signal to output. The timing generation circuit extracts and outputs a transmission data generation timing pulse based on the timing at which the timing information takes a predetermined value. Thus, the retiming circuit retiming of the transmission data using the extracted generated timing pulse.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a data transmission system according to one embodiment of the present invention. In this figure,
Timing information generation circuit 11, the transmission data D _0, D ₁ to be _{transmitted, ......, D k, ...... D} n generated timing pulse a _{0 in, a 1, ......, a k} , ...... a n (0 ≦ k ≦ n) and transmission timing pulses b ₀ , b ₁ ,..., B _p ,... B _m (0 ≦ p ≦ m) output from the transmitter 12 constituting the transmission device.
Comparing the door, takes the value "1" when the generation timing pulses a _k and transmission timing pulses b _p matches the parity signal P ₀ which takes a value "0" otherwise, P _1, ...
.., P _k ,..., P _n are generated as timing information. Encoding circuit 13, the transmission data D ₀ to D _n and the timing information (parity signal) P ₀ to P _n and the encoded signal S ₀ and convolutional coding _{together, S 1, ......, S k} , ...... and outputs the S _n. Transmitter 12 takes based on the transmission timing pulses b ₀ ~b _m of the transmission apparatus a coded signal S ₀ to S _n, and transmits same to the receiver 14 constituting the transmission device.

[0010] The receiver 14 transmits the encoded signal S _0.
ＳS _n are supplied to the maximum likelihood decoding circuit 15. Maximum likelihood decoding circuit 15, maximum likelihood decoding the coded signal S ₀ to S _n,
From the decoded signal transmission data D _'0 to D' _n and timing information P _'0 to P' separates the _n outputs. The data timing generation circuit 16 determines that the timing information P ′ _{0 to} P ′ _n has a value “
The transmission data D ′ _0-
D ′ _n generation timing pulses a ′ ₀ , a ′ ₁ ,..., A ′ _k ,
... _a'n (0≤k≤n) is extracted and output. The retiming circuit 17 extracts the generated timing pulse a ′ ₀
The ₀ to D _'n and retiming outputs the received data D ₀ to D _n' transmission data D with _n '~a.

FIG. 2 shows an example of an algorithm for generating the timing information P _{0 to} P _n in the timing information generation circuit 11. As can be seen from FIG. 2, the timing information P _{0 to} P _n is the transmission data D
₀ and to D _n generated timing pulse a ₀ ~a _n of takes a value "1" only if the transmission timing pulses b ₀ ~b _m matches, one parity takes a value "0" in other cases Signal.

Next, FIG. 3 shows a convolutional code (r = 3 /
4, k = 2, (40 56 63 74)). In the figure, reference numeral 21 denotes each state of the encoding circuit 13. Further, in FIG. 4, in the encoding circuit 13 shows the state transition of the encoded signal S ₀ to S _n of the timing information P _k and the transmission data D _k are simultaneously coded. When the timing information P _k takes the value “0”, since the transmission data D _k does not change, it can be seen from FIG. 4 that the code state transition is restricted (state transition is deleted). As a result, according to this embodiment, the error correction effect increases, and an error correction effect corresponding to the timing period ratio can be obtained.

As described above, according to the data transmission system of this embodiment, transmission data having an arbitrary transmission speed can be transmitted, and a line corresponding to the importance of the transmission data can be transmitted without interruption. Quality can be obtained.

Incidentally, the error correction capability increases as the transmission speed becomes slower than the transmission timing speed. Therefore, by delaying the transmission timing of the portion of the transmission data where the importance of the information is high, efficient signal transmission becomes possible. FIG. 5 shows a configuration example of a data transmission system in which the transmission timing speed is varied according to the importance of information. 5, the data transmission terminal 31, 32 the data importance degree detecting circuit, 33 is the transmission rate control circuit, b _p is the transmission timing pulses, 34 a data transmission system according to an embodiment described above, D '' _k transmission This is transmission data whose line quality has been improved according to the importance of the data. Also, FIG. 6 is a representation of the relationship between importance and the transmission timing b _p of the transmission data D _k in FIG. 5, in this figure, 35 is out of the transmission data D _k, the place with important data Is shown. As can be seen from FIG. 6, by delaying the transmission timing for transmission data having important information, the error correction capability is increased and the line quality is improved.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and a design change or the like may be made without departing from the gist of the present invention. The present invention is also included in the present invention. For example, the data transmission system according to the above-described embodiment can make the transmission speed of transmission data and the transmission speed of the transmission device asynchronous, so that it can be easily applied to a transmission system that performs start-stop synchronization.

[0016]

According to the present invention, transmission data having an arbitrary transmission rate can be transmitted, and high line quality can be obtained. Further, since there is no switching portion, instantaneous interruption due to switching does not occur.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a data transmission system according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a timing information generation algorithm of a timing information generation circuit 11 shown in FIG. 1;

FIG. 3 is a diagram illustrating an example of state transition of a convolutional code in the data transmission system illustrated in FIG.

FIG. 4 is a diagram illustrating an example of a state transition of an encoded signal when timing information and transmission data are encoded simultaneously in the data transmission system illustrated in FIG. 1;

FIG. 5 is a block diagram illustrating an application example of the data transmission system illustrated in FIG.

FIG. 6 is a diagram illustrating a relationship between importance of transmission data and transmission timing in the data transmission system illustrated in FIG. 5;

FIG. 7 is a block diagram illustrating a configuration example of a conventional data transmission system.

[Explanation of symbols]

 Reference Signs List 11 timing information generating circuit 12 transmitter 13 encoding circuit 14 receiver 15 maximum likelihood decoding circuit 16 data timing generating circuit 17 retiming circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 1/00 H03M 13/00 H04L 7/00 H04L 25/00

Claims (1)

(57) [Claims] 1. A data transmission system for transmitting transmission data having different transmission speeds using the same transmission device having a constant transmission speed, wherein: a transmission timing pulse of the transmission data; and a transmission timing output from the transmission device. Pulse, and takes a first value when the generation timing pulse and the transmission timing pulse match, and takes a second value in other cases.
A timing information generation circuit that generates timing information that takes a value of, a coding circuit that convolutionally codes the transmission data and the timing information together and outputs a coded signal, A transmitter that captures the encoded signal based on the transmission timing and transmits the signal, a receiver that constitutes the transmission device and receives the transmitted encoded signal, and performs maximum likelihood decoding of the encoded signal and decodes the encoded signal. A maximum likelihood decoding circuit that separates and outputs transmission data and timing information from a signal; and a timing generation circuit that extracts and outputs a generation timing pulse of the transmission data based on a timing at which the timing information takes a predetermined value. And a retiming circuit for retiming transmission data using the extracted generated timing pulse. Over data transmission system.