JP3761456B2 - Data communication apparatus, communication data error detection method, data communication system - Google Patents

Description

従って，前記誤り発生符号数がｎ個である期待値＜ｎ＞は，次の（２）式で表すことができる。
【数２】

前述したように，本データ通信システムＸでは，前記サンプリング単位データにおいて，前記誤り発生符号数を前記バースト内符号数Ｍで除したときの余りｎ’（＝ｎ ｍｏｄ（Ｍ））を前記ランダム誤りの発生数とするので，該ランダム誤りの発生数ｎ’の期待値＜ｎ’＞は，次の（３）式で表すことができる。
【数３】

従って，本データ通信システムＸで算出される前記ランダム誤りの発生率（以下，単にランダム誤りの発生率ｐ’eという）は，次の（４）式で表すことができる。
【数４】

ここで，「前記真のランダム誤りの発生率ｐeと前記ランダム誤りの発生率ｐ’eとの差を，前記真のランダム誤り発生率ｐeで除した値」を前記ランダム誤りの発生率ｐ’eの誤差Ｅｒ（Ｎ，ｐe）と定義すると，該誤差Ｅｒ（Ｎ，ｐe）は，次の（５）式で表すことができる。
【数５】

この（５）式に，前記（１）式，（３）式，及び（４）式を代入すると，次の（６）式が導かれる。
【数６】

この（６）式より求まる前記誤差Ｅｒ（Ｎ，ｐe）が所定の値以下となるようにできれば，前記ランダム誤りの発生率ｐ’eは信頼できる値となり，前記誤判定を防止できる。
【００１５】
ここで，（６）式によれば，前記真のランダム誤りの発生率ｐeが大きくなるほど，前記誤差Ｅｒ（Ｎ，ｐe）が大きくなることがわかる。そして，前記サンプリング符号数Ｎのそれぞれにおいて，前記誤差Ｅｒ（Ｎ，ｐe）が所定の値（例えば，０．１）となるような前記真のランダム誤りの発生率ｐeを求めると，図３に示すグラフとなる。
図３のグラフにおいて，横軸は前記サンプリング符号数Ｎ，縦軸は前記真のランダム誤りの発生率ｐeであり，前記誤差Ｅｒ（Ｎ，ｐe）が０．１となるときの前記サンプリング符号数Ｎ及び前記真のランダム誤りの発生率ｐeの関係を実線で示している。これにより，図３のグラフにおいて，実線の上側（前記真のランダム誤りの発生率ｐeが大きい方）の領域が，前記誤差Ｅｒ（Ｎ，ｐe）が０．１を越える領域を表し，同下側の領域が，前記誤差Ｅｒ（Ｎ，ｐe）が０．１未満となる領域を表すこととなる。即ち，図３のグラフは，前記誤差Ｅｒ（Ｎ，ｐe）を０．１未満とするための，前記サンプリング符号数Ｎに対応する前記ランダム誤りの発生率ｐeの許容値（前記誤り発生率の許容値に該当）を表すものである。
この図３のグラフを用いることにより，前記真のランダム誤りの発生率ｐeが上昇した場合に，前記真のランダム誤りの発生率ｐeが，図３のグラフの下側に位置するように前記サンプリング符号数Ｎを小さく設定し，前記真のランダム誤りの発生率ｐeが図３のグラフより余裕をもって下回れば，その余裕分だけ前記サンプリング符号数Ｎ大きく設定することにより，前記誤差Ｅｒ（Ｎ，ｐe）を０．１未満に維持できる範囲で最大の前記サンプリング符号数Ｎとすることができる。しかし，前記真のランダム誤り率ｐeを算出することはできないため，これに代わるものを代替して用いる必要がある。
【００１６】
本データ通信システムＸでは，前記ランダム誤り率ｐeの代替値として，前記誤り発生符号数を前記サンプリング符号数で除した値である総誤り発生率ｐeaを用いる。理由を以下に説明する。
前記総誤り発生率ｐeaは，前記バースト誤りと前記ランダム誤りの両方を含むものであり，前記新のランダム誤りの発生率ｐe以上となるものである。従って，図３のグラフを用いた前記サンプリング符号数Ｎの設定の際に，前記真のランダム誤り率ｐeの代わりに前記総誤り発生率ｐeaを適用すれば，前記バースト誤りを含む分だけ余裕を持って，前記サンプリング符号数Ｎが設定されることとなり，結果的に，前記誤差Ｅｒ（Ｎ，ｐe）を所定値（＝０．１）未満に維持することが可能となる。
これにより，前記ランダム誤りがの発生数が増えた場合でも，前記ランダム誤りを前記バースト誤りとしてカウントしてしまう前記誤判定を防止することが可能となり，適切に前記バースト誤りと前記ランダム誤りとを区分して検出できることとなる。
【００１７】
本データ通信システムＸでは，前記サンプリング符号数Ｎを前記誤り訂正符号化復号化装置２１，２２に直接設定することができないため，各時点の前記サンプリング符号数Ｎと前記サンプリング周期により，通信データに含まれる時間当たりの前記誤り符号数を求め，これにより，以後の前記サンプリング符号数Ｎが所望の数（図３のグラフで示される前記真のランダム誤りの発生率ｐeが前記総誤り発生率ｐea以上になる前記サンプリング符号数Ｎ）となるように，前記サンプリング周期を設定（変更）する。この設定（変更）は，前記通信状態判定装置４１，４２から前記通信制御装置３１，３２を介して前記誤り訂正符号化復号化装置２１，２２に対して行われる。
前記サンプリング符号数Ｎの設定（即ち，前記サンプリング単位データの設定）の他の方法としては，受信側から送信側に対し，所定の送信データ量制御指令を送信し，単位時間当たりの通信データの送信許容量を変更させる方法や，これと前記サンプリング周期の設定（変更）とを組み合わせる方法等も考えられる。もちろん，前記誤り訂正符号化復号化装置２１，２２に対して前記サンプリング符号数Ｎを直接設定できるよう構成してもよい。
【００１８】
また，本データ通信システムＸでは，前記バースト誤りの発生率と前記ランダム誤りの発生率とを区分して検出することができるので，それぞれの要因に対応した適切な対応が可能である。
例えば，前記ランダム誤りの発生率が，所定の上限値を越えた場合には，２つの前記通信制御装置３１，３２間の通信により，受信側から送信側に対し，通信データの出力信号の強度をより強く変更させる指令を送信し，前記ランダム誤りの発生率が，所定の下限値を下回った場合には，同様に通信データの出力信号の強度を元に戻させる指令を送信する。これにより，主としてＳＮ比の低下が原因である前記ランダム誤りの発生を抑制することが可能となる。同様に，前記ランダム誤りの発生率に基づいて，受信側から送信側に対し，送信側の前記変復調装置１１の変調方式や，前記誤り訂正符号化復号化装置２１における前記誤り訂正符号の符号化方式を変更させる指令を送信するとともに，これに対応させて受信側の前記変復調装置１２の復調方式や，前記誤り訂正符号化復号化装置２２の誤り訂正の方式を変更するよう構成してもよい。これにより，前記ランダム誤りの発生率が上昇した場合に，多値化レベルの低い変調方式に切り替えたり，前記誤り訂正符号の符号長を長くする等，データの伝送容量よりも耐ノイズ性を優先した変調方式に切り替えれば，通信の安定性を保持することができる。
一方，前記バースト誤りの発生率に基づいて，受信側から送信側に対し，前記変復調装置１１における変調パラメータであるプリアンブル長を変更させる変更させる指令を送信し，これに対応させて受信側の前記変復調装置１２における復調時のプリアンブル長を変更するよう構成してもよい。これにより，前記バースト誤りの発生率が上昇した場合に，プリアンブル長を長くしてデータの伝送容量よりも信号の同期の取りやすさを優先した変調パラメータに切り替えれば，前記バースト誤りの発生を抑制でき，通信の安定性を保持することができる。
【００１９】
【発明の効果】
以上説明したように，本発明によれば，通信データに発生するランダム誤りとバースト誤りとを区分して検出できるとともに，誤りの種類に応じて適切な対応を行うことが可能である。
【図面の簡単な説明】
【図１】本発明の実施の形態に係る通信システムＸの概略構成を表すブロック図。
【図２】本発明の実施の形態に係る通信システムＸにおける通信データの１サンプル当たりに誤りが生じていた誤り訂正符号の数それぞれの発生確率の分布の一例を表すグラフ。
【図３】本発明の実施の形態に係る通信システムＸが通信データのサンプリング周期を変更するために用いるグラフであってサンプリングした誤り訂正符号数と誤り発生率との関係の一例を表すグラフ。
【符号の説明】
１，２…通信装置
１１，１２…変復調装置
２１，２２…誤り訂正符号化復号化装置
３１，３２…通信制御装置
４１，４２…通信状態判定装置
５１，５２…端末装置
６０…通信ケーブル[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data communication apparatus that receives communication data that has been encoded into a predetermined error correction code and performs error correction of the communication data based on an error correction code included in the communication data.
[0002]
[Prior art]
Conventionally, for example, data communication for composing communication data in units of burst signals, which are data strings of a predetermined length, as in the case of composing communication data in units of IP packets in communication using the IP protocol. There is a device. In addition, in order to cope with errors in communication data caused by noise in the communication path, communication data is transmitted by the burst signal (IP packet etc.) that has been encoded into a predetermined error correction code such as a Reed-Solomon code. In general, the error correction of communication data is performed on the receiving side based on the error correction code included in the communication data. According to the Reed-Solomon code, etc., in addition to being able to correct an error, it is also possible to detect whether an error has occurred for each error correction code or whether the error has been correctly corrected by error correction. . Therefore, it is possible to detect the number of error-correcting codes in which an error has occurred (hereinafter referred to as the number of error codes) and the number of error-correcting codes that cannot be corrected (hereinafter referred to as the number of uncorrectable codes). Using these pieces of information, the ratio of the number of error codes or the number of uncorrectable codes to the number of all error correction codes (hereinafter referred to as the number of sampling codes) included in a predetermined sampling unit of communication data is obtained. Thus, it is possible to obtain the error occurrence rate before or after correcting the error.
[0003]
By the way, communication data errors in the communication path are caused by the cause of the error, such as an error that occurs randomly without any regularity in bit units of the communication data (hereinafter referred to as random error), and the failure of synchronization of the burst signal. Thus, it is divided into errors that occur in the entire unit of the burst signal (hereinafter referred to as burst errors). In the burst error, an error occurs in all error correction signals included in the burst signal, and the error correction cannot be performed in many cases. Further, the random error and the burst error have different measures for suppressing the occurrence thereof. For example, the occurrence of the random error is often caused by a decrease in the S / N ratio due to a large attenuation of a communication signal level in a communication path or a high noise level. Encoding to an error correction code with higher correction capability by increasing the strength of the output signal, changing to a modulation method that is more resistant to noise, and increasing the size of the error correction code (encoding method) ) Is effective. On the other hand, the occurrence of the burst error is often caused by the failure of the synchronization of the burst signal as described above. In this case, the signal is generated by increasing the preamble length among the modulation parameters of the burst signal. It is effective to make it easier to synchronize.
[0004]
[Problems to be solved by the invention]
However, conventionally, since the random error and the burst error cannot be detected separately, for example, when the burst error is dominant, the signal output intensity on the transmission side is increased, and thus, appropriate There was a problem that it might not be possible to respond.
Therefore, the present invention has been made in view of the above circumstances, and the object of the present invention is to be able to detect the random error and the burst error generated in communication data separately and according to the type of error. It is an object of the present invention to provide a data communication apparatus, a communication data error detection method, and a data communication system capable of appropriately responding.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention receives communication data configured in units of a burst signal, which is a data string of a predetermined length that has been encoded into a predetermined error correction code. A data communication device that performs error correction of the communication data based on the included error correction code, and a sampling code number that is the number of the error correction code included in a predetermined sampling unit of the received communication data; In a data communication apparatus comprising error information detecting means for detecting error information relating to the number of error correcting codes in which an error is detected or the number of error generating codes that is the number of error correcting codes that cannot be corrected. , Based on a predetermined number of intra-burst codes, which is the number of error correction codes included in one burst signal, and the error information, A burst error is an error that occurs throughout the unit of bets signals, and other data communication apparatus characterized by comprising; and a error detection means for detecting by dividing the random error is an error.
As described above, when the burst error occurs, an error occurs in all error correction codes included in one burst signal. Therefore, the number of error generation codes is added in units of multiples of the number of codes in the burst. The Rukoto.
Therefore, the error detection means uses the quotient obtained by dividing the number of error-generating codes by the number of intra-burst codes as the number of burst errors, and the remainder as the number of random errors. If the rate and the random error occurrence rate are calculated separately, the burst error and the random error can be detected separately.
[0006]
Further, it is possible to change the sampling unit of the communication data by the error information detecting means based on the error information. For example, the error information is based on a comparison between an error occurrence rate that is a ratio of the error occurrence code number to the sampling code number and an allowable value of the error occurrence rate that is set in advance corresponding to the sampling code number. For example, the sampling unit of the communication data by the detecting means is changed.
As a result, when the number of occurrences of the random error is increased to more than the number of codes in the burst, it is possible to prevent an erroneous determination that erroneously counts what should originally be counted as the random error as the burst error. . That is, for each sampling code number, the probability of occurrence of a predetermined number of random errors can be calculated theoretically. Based on this, when the burst error and the random error are distinguished by the above-described method, For each sampling code number, it is possible to theoretically obtain in advance an allowable value of the error occurrence rate for keeping the probability of erroneous determination (detection error of the number of occurrences of random errors) within a predetermined allowable range. Since the allowable value of the error rate is higher as the number of sampling codes is smaller (FIG. 3 to be described later), the number of sampling codes is adjusted so that the error rate does not exceed the allowable value (ie, If the sampling unit is changed, the erroneous determination can be prevented, and the sampling unit is increased as much as possible (increasing the number of sampling codes) to be more accurate (having a large parameter). ) The random error occurrence rate and the burst error occurrence rate can be obtained.
[0007]
Further, it is conceivable that the sampling unit of the communication data is the communication data received during a predetermined sampling period. In this case, changing the sampling unit of the communication data changes the sampling period. Or transmission of the communication data Original It is conceivable that a predetermined transmission data amount control command is transmitted to the communication data to change the allowable transmission amount of the communication data per unit time.
Thereby, even if the sampling number cannot be changed directly, the sampling unit (the sampling number) can be changed.
[0008]
The transmission of the communication data is based on the random error occurrence rate. Original Sending a command to change the strength of the output signal of the communication data, or sending the communication data Original A command for changing the modulation method of the communication data, and changing the demodulation method of the demodulating means of the communication data included in the data communication device in response to the command, and further transmitting the communication data Original A command for changing the encoding method of the error correction code is transmitted to the terminal, and the error correction method based on the error correction code included in the communication data is changed correspondingly.
As a result, when the random error occurs, it is possible to cope with appropriate error suppression corresponding to the cause of the occurrence.
[0009]
Further, based on the burst error occurrence rate, a command for changing a preamble length, which is a modulation parameter of the communication data, is transmitted to the transmission destination of the communication data, and the data communication apparatus is provided corresponding to this command. It is possible to change a parameter relating to the preamble length of the communication data demodulating means.
As a result, when the burst error occurs, appropriate error suppression corresponding to the cause of the occurrence can be performed.
Further, an error detection function possessed by the data communication apparatus can be considered as a communication data error detection method, and a data communication system having the data communication apparatus can be considered.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
1 is a block diagram showing a schematic configuration of the communication system X according to the embodiment of the present invention, and FIG. 2 is an error per sample of communication data in the communication system X according to the embodiment of the present invention. FIG. 3 is a graph showing an example of the distribution of occurrence probabilities for each number of error correction codes, and FIG. 3 is a graph used by the communication system X according to the embodiment of the present invention to change the sampling period of communication data. It is a graph showing an example of the relationship between the number of error-correcting codes and the error occurrence rate.
[0011]
First, the configuration of the communication system X according to the embodiment of the present invention will be described with reference to FIG.
The communication system X performs data communication between two terminal devices 51 and 52 using an IP protocol via communication devices 1 and 2 connected to the terminal devices 51 and 52, respectively. The terminal devices 51 and 52 and the communication devices 1 and 2 are the same, and can be both a transmission side and a reception side. However, for convenience of explanation, the terminal device 51 and the communication device 1 are hereinafter referred to as the transmission side, The terminal device 52 and the communication device 2 will be described as the receiving side.
The communication data output from the terminal device 51 is processed by the error correction coding / decoding device 21 using an IP packet included in the communication data as a burst signal unit, for example, a Reed-Solomon code as a 1500-byte fixed length packet. The digital signal is encoded by an error correction code such as QPSK, 16QAM, or 64QAM, and then transmitted to the receiving side via the communication cable 60.
On the other hand, on the receiving side, the communication data subjected to the digital modulation is demodulated by the modem 12 and further, the error correction coding / decoding device 22 performs the error contained in the communication data. correction Based on the code, error correction is performed and then output to the terminal device 52. At this time, when the error correction coding / decoding device 22 performs error correction, the error included in the communication data is transmitted. correction The number of codes, the error in which an error has occurred correction Number of codes and the error that could not be corrected correction Count the number of codes.
The encoding method to the error correction code by the error correction encoding / decoding devices 21 and 22 and the modulation and demodulation method by the modulation / demodulation devices 11 and 12 can be selected from a plurality of types. The selection is controlled by communication control devices 31 and 32 that are communicably connected to the error correction coding / decoding devices 21 and 22 and the modems 11 and 12. Further, the two communication control devices 31 and 32 are configured to exchange predetermined commands with each other via the modulation and demodulation devices 11 and 12 by a unique communication protocol.
Further, the error correction coding devices 21 and 22 and the communication control devices 31 and 32 are connected to communication state determination devices 41 and 42 constituted by a CPU, a ROM, a RAM and the like (not shown) so that they can communicate with each other. Has been. In FIG. 1, the communication state determination devices 41 and 42 are provided in the communication devices 1 and 2, respectively, but these are provided separately from the communication devices 1 and 2, for example, a public line or a dedicated line. It is good also as a structure installed in a remote place via.
The communication state determination device 42 transmits a predetermined error information request to the error correction coding / decoding device 22 at a predetermined sampling period, and in response thereto, the error correction coding / decoding device 22 transmits the communication request to the error correction coding / decoding device 22. A sampling code number that is the number of error correction codes included in the communication data received during the sampling period (hereinafter, this communication data unit is referred to as sampling unit data) to the state determination device 42; Among them, the number of error-generating codes, which is the number of error-correcting codes in which errors are detected, is returned as error information. As the number of error generating codes, focusing on communication data after error correction, the number of error correcting codes that could not be corrected for error may be returned. The error information is used to determine the occurrence rate of the random error and the burst error, which will be described later. The configuration of the communication system X is not particularly different from that of a general communication system except that the communication state determination devices 41 and 42 are provided.
[0012]
Next, the number of error generating codes acquired by the communication status determination devices 41 and 42 from the error correction coding / decoding devices 21 and 22 will be described with reference to FIG.
FIG. 2 shows that when the number of error generating codes is input from the error correction coding / decoding device 22 a predetermined number of times, the number of error generating codes to be input is set on the horizontal axis and the number of error generating codes is integrated. It is an example of a graph representing a probability distribution for each of the number of error occurrence codes, with the ratio of the number of inputs to the total number of inputs (distribution probability) as the vertical axis. The example of FIG. 2 shows the error included in one IP packet (the burst signal). correction The number of codes (hereinafter referred to as the number of codes in a burst) is 7, and the data in the situation where the burst error has occurred is graphed.
As shown in FIG. 2, when the burst error occurs, the error included in the unit of the burst signal. correction Since errors occur in all codes, the number of error-generating codes indicates a distribution that increases the probability that the number of intra-burst codes (= 7). Although not occurring in FIG. 2, when a plurality of burst errors occur, the number of error generating codes corresponding to a multiple of the number of intraburst codes is detected. On the other hand, it is due to the random error that a high probability distribution is shown when the number of error-generating codes is 3 or less. The present invention distinguishes and detects the burst error and the random error by paying attention to the characteristics of the burst error.
Specifically, the communication state determination devices 41 and 42 divide the number of error-generating codes for each sampling unit data by the number of intra-burst codes and use the quotient as the number of burst errors, and the remainder. The number of occurrences of random errors is calculated, and the ratio of the number of occurrences of burst errors and the number of occurrences of random errors to the number of sampling codes is calculated as a burst error rate and a random error rate, respectively.
As a result, the number of burst errors detected as a multiple of the number of intra-burst codes and the number of other random errors can be detected separately.
[0013]
By the way, when the actual number of random errors included in the sampling unit data (hereinafter referred to as the true number of random errors) is smaller than the number of intra-burst codes, the burst error is determined by the method described above. And the random error can be appropriately classified, but when the number of occurrences of the true random error increases to more than the number of intra-burst codes, what should be detected as the random error is detected as the burst error. A misjudgment such as will occur. This misjudgment becomes more prominent because the longer the sampling period, the larger the number of sampling codes, the greater the number of occurrences of the true random errors included therein. Conversely, by reducing the size of the sampling unit data, that is, shortening the sampling period, the number of occurrences of the true random error included in the sampling unit data can be reduced, and the erroneous determination is performed. Can be prevented.
On the other hand, in order to reduce the detection load of the error information during communication, it is desirable that the sampling period is long. Therefore, in this data communication system X, in order to prevent the erroneous determination, the sampling period is changed according to the communication state.
[0014]
Hereinafter, the change of the sampling cycle executed by the communication state determination device will be described.
Here, when the number of sampling codes is N, the number of intra-burst codes is M, and the occurrence rate of the true random error is pe, the error in the sampling unit data when the burst error does not occur. The probability Pr (n) when the number of generated codes is n can be expressed by the following equation (1).
[Expression 1]

Therefore, the expected value <n> where the number of error generating codes is n can be expressed by the following equation (2).
[Expression 2]

As described above, in the data communication system X, in the sampling unit data, the remainder n ′ (= n mod (M)) when the number of error-generating codes is divided by the number of intra-burst codes M is the random error. Therefore, the expected value <n ′> of the random error occurrence number n ′ can be expressed by the following equation (3).
[Equation 3]

Accordingly, the random error occurrence rate calculated by the data communication system X (hereinafter simply referred to as random error occurrence rate p′e) can be expressed by the following equation (4).
[Expression 4]

Here, “the value obtained by dividing the difference between the true random error rate pe and the random error rate p′e by the true random error rate pe” is the random error rate p ′. If the error Er (N, pe) of e is defined, the error Er (N, pe) can be expressed by the following equation (5).
[Equation 5]

Substituting the above formulas (1), (3), and (4) into this formula (5) leads to the following formula (6).
[Formula 6]

If the error Er (N, pe) obtained from the equation (6) can be set to a predetermined value or less, the random error occurrence rate p′e becomes a reliable value, and the erroneous determination can be prevented.
[0015]
Here, according to equation (6), it can be seen that the error Er (N, pe) increases as the true random error occurrence rate pe increases. Then, when the true random error occurrence rate pe is obtained such that the error Er (N, pe) becomes a predetermined value (for example, 0.1) at each of the sampling code numbers N, FIG. It becomes a graph to show.
In the graph of FIG. 3, the horizontal axis represents the number of sampling codes N, the vertical axis represents the true random error occurrence rate pe, and the number of sampling codes when the error Er (N, pe) is 0.1. The relationship between N and the true random error occurrence rate pe is indicated by a solid line. Thus, in the graph of FIG. 3, the region above the solid line (where the true random error occurrence rate pe is larger) represents the region where the error Er (N, pe) exceeds 0.1. The side region represents a region where the error Er (N, pe) is less than 0.1. That is, the graph of FIG. 3 shows an allowable value of the random error occurrence rate pe corresponding to the sampling code number N (the error occurrence rate of the error occurrence rate) in order to make the error Er (N, pe) less than 0.1. Represents a permissible value).
When the true random error occurrence rate pe is increased by using the graph of FIG. 3, the sampling is performed so that the true random error occurrence rate pe is located on the lower side of the graph of FIG. If the code number N is set small, and the true random error occurrence rate pe falls below the graph of FIG. 3, the error Er (N, pe) is set by increasing the sampling code number N by the margin. ) Can be set to the maximum number of sampling codes N within a range in which it can be maintained below 0.1. However, since the true random error rate pe cannot be calculated, it is necessary to use a substitute for this.
[0016]
In the data communication system X, the total error occurrence rate pea, which is a value obtained by dividing the number of error occurrence codes by the number of sampling codes, is used as an alternative value for the random error rate pe. The reason will be described below.
The total error occurrence rate pea includes both the burst error and the random error, and is equal to or higher than the new random error occurrence rate pe. Therefore, when setting the number N of sampling codes using the graph of FIG. 3, if the total error occurrence rate pea is applied instead of the true random error rate pe, a margin corresponding to the burst error is provided. Therefore, the sampling code number N is set, and as a result, the error Er (N, pe) can be maintained below a predetermined value (= 0.1).
As a result, even when the number of occurrences of the random error increases, it is possible to prevent the erroneous determination that the random error is counted as the burst error, and the burst error and the random error are appropriately displayed. It will be possible to detect by dividing.
[0017]
In the present data communication system X, the sampling code number N cannot be set directly in the error correction coding / decoding devices 21 and 22. Therefore, the communication data is determined according to the sampling code number N and the sampling period at each time point. The number of included error codes per unit time is obtained, so that the number of subsequent sampling codes N is a desired number (the true random error occurrence rate pe shown in the graph of FIG. 3 is the total error occurrence rate pea). The sampling period is set (changed) so that the number of sampling codes N) becomes the above. This setting (change) is caused by the error from the communication state determination devices 41 and 42 via the communication control devices 31 and 32. correction This is performed for the encoding / decoding devices 21 and 22.
As another method of setting the sampling code number N (that is, setting the sampling unit data), a predetermined transmission data amount control command is transmitted from the reception side to the transmission side, and communication data per unit time is set. A method of changing the allowable transmission amount, a method of combining this with the setting (change) of the sampling period, and the like are also conceivable. Of course, the sampling code number N may be directly set to the error correction coding / decoding devices 21 and 22.
[0018]
Further, in the data communication system X, since the burst error occurrence rate and the random error occurrence rate can be detected separately, an appropriate response corresponding to each factor is possible.
For example, when the random error occurrence rate exceeds a predetermined upper limit value, the communication signal output signal strength from the reception side to the transmission side is communicated between the two communication control devices 31 and 32. When the random error occurrence rate falls below a predetermined lower limit value, a command for returning the strength of the output signal of the communication data is similarly transmitted. As a result, it is possible to suppress the occurrence of the random error mainly due to a decrease in the SN ratio. Similarly, the modulation scheme of the modem 11 on the transmission side and the encoding of the error correction code in the error correction coding / decoding device 21 from the reception side to the transmission side based on the random error occurrence rate. A command for changing the method may be transmitted, and the demodulation method of the modulation / demodulation device 12 on the receiving side and the error correction method of the error correction coding / decoding device 22 may be changed correspondingly. . As a result, when the incidence of random errors increases, priority is given to noise resistance over data transmission capacity, such as switching to a modulation scheme with a low multi-level or increasing the code length of the error correction code. By switching to the modulation method, communication stability can be maintained.
On the other hand, based on the occurrence rate of the burst error, a command for changing the preamble length, which is a modulation parameter in the modem 11, is transmitted from the receiving side to the transmitting side, and the receiving side responds to the change command. You may comprise so that the preamble length at the time of the demodulation in the modem 12 may be changed. As a result, when the occurrence rate of the burst error increases, the occurrence of the burst error can be suppressed by increasing the preamble length and switching to a modulation parameter that prioritizes the ease of signal synchronization over the data transmission capacity. Communication stability can be maintained.
[0019]
【The invention's effect】
As described above, according to the present invention, random errors and burst errors that occur in communication data can be detected separately, and appropriate measures can be taken according to the type of error.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of a communication system X according to an embodiment of the present invention.
FIG. 2 is a graph showing an example of distribution of occurrence probabilities for each number of error correction codes in which an error has occurred per sample of communication data in the communication system X according to the embodiment of the present invention.
FIG. 3 is a graph used by the communication system X according to the embodiment of the present invention to change the sampling period of communication data, and shows an example of the relationship between the number of sampled error correction codes and the error rate.
[Explanation of symbols]
1, 2 ... Communication device
11, 12 ... modem
21, 22 ... Error correction coding / decoding device
31, 32 ... Communication control device
41, 42 ... Communication state determination device
51, 52 ... Terminal equipment
60 ... Communication cable

Claims (12)

Receiving communication data configured in units of a burst signal, which is a data string of a predetermined length that has been encoded into a predetermined error correction code, and performing the communication based on the error correction code included in the communication data A data communication apparatus that performs error correction of data, the number of sampling codes that is the number of the error correction codes included in a predetermined sampling unit of the received communication data, and the error correction code in which an error is detected In a data communication apparatus comprising error information detection means for detecting error information relating to the number of error-generating codes that is the number or the number of error-correcting codes that could not be corrected,
Based on a predetermined number of intra-burst codes that are the number of error correction codes included in one burst signal and the error information, a burst error that is an error that occurs in the entire unit of the burst signal, and other errors A data communication apparatus comprising: error detection means for detecting and detecting random errors that are   The error detection means uses the quotient obtained by dividing the number of error generating codes by the number of intra-burst codes as the number of burst errors, and the remainder as the number of random errors. The data communication apparatus according to claim 1, wherein the random error occurrence rate is calculated separately.   3. The data communication apparatus according to claim 1, wherein the sampling unit of the communication data by the error information detection unit is changed based on the error information.   The error information detecting means is based on a comparison between an error occurrence rate which is a ratio of the error occurrence code number to the sampling code number and an allowable value of the error occurrence rate set in advance corresponding to the sampling code number. The data communication apparatus according to claim 3, wherein the sampling unit of the communication data is changed.   The data communication apparatus according to any one of claims 1 to 4, wherein the sampling unit of the communication data is the communication data received during a predetermined sampling period. Changing the sampling unit of the communication data changes the sampling cycle, or changes the allowable transmission amount of the communication data per unit time by sending a predetermined transmission data amount control command to the transmission source of the communication data The data communication apparatus according to claim 5, wherein the data communication apparatus is performed by one or both of the steps. The data communication apparatus according to any one of claims 2 to 6, wherein a command for changing an intensity of an output signal of the communication data is transmitted to a transmission source of the communication data based on the occurrence rate of the random error. Based on the occurrence rate of the random error, a command for changing the modulation method of the communication data is transmitted to the transmission source of the communication data, and the communication data demodulating means included in the data communication device corresponding to the command is transmitted. The data communication apparatus according to claim 2, wherein the demodulation method is changed. Based on the occurrence rate of the random error, a command for changing the encoding method of the error correction code is transmitted to the transmission source of the communication data, and the error correction code included in the communication data is associated with this instruction. 9. The data communication apparatus according to claim 2, wherein the error correction method based on the data correction is changed. Based on the occurrence rate of the burst error, a command for changing a preamble length, which is a modulation parameter of the communication data, is transmitted to the transmission source of the communication data, and the communication included in the data communication apparatus corresponding to the command is transmitted. 10. The data communication apparatus according to claim 2, wherein a parameter relating to the preamble length of the data demodulating unit is changed. In an error detection method for communication data configured in units of burst signals, which are data strings of a predetermined length encoded into a predetermined error correction code,
The number of error correction codes included in a predetermined sampling unit of the communication data and the number of error correction codes in which an error is detected or the number of error correction codes in which an error cannot be corrected The error occurs in the entire unit of the burst signal based on the error information regarding the number of error generating codes and the predetermined number of intra-burst codes which is the number of error correction codes included in one burst signal. An error detection method for communication data, wherein a burst error and a random error which is another error are detected separately. A first data communication device that transmits communication data configured in units of burst signals, which are data strings of a predetermined length that have been encoded into a predetermined error correction code;
The number of error correction codes included in a predetermined sampling unit of the communication data while performing error correction of the communication data based on the error correction code included in the communication data received from the first data communication device A second error detection unit that detects error information related to the number of sampling codes and the number of error correction codes in which an error is detected or the number of error generation codes that is the number of error correction codes that cannot be corrected. In a data communication system having a data communication device,
A predetermined intra-burst code that is configured to be communicable with the first data communication device and is the number of the error correction code received in the burst information and the error information received from the first data communication device And an error detection device for detecting a burst error that is an error occurring in the entire unit of the burst signal and a random error that is another error based on the number of the error signals. Data communication system.

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