JPH0214823B2 - - Google Patents
Info
- Publication number
- JPH0214823B2 JPH0214823B2 JP57136574A JP13657482A JPH0214823B2 JP H0214823 B2 JPH0214823 B2 JP H0214823B2 JP 57136574 A JP57136574 A JP 57136574A JP 13657482 A JP13657482 A JP 13657482A JP H0214823 B2 JPH0214823 B2 JP H0214823B2
- Authority
- JP
- Japan
- Prior art keywords
- signal
- stations
- code
- transmission
- rule
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000005540 biological transmission Effects 0.000 claims description 30
- 238000004891 communication Methods 0.000 claims description 17
- 238000001514 detection method Methods 0.000 claims description 13
- 238000010586 diagram Methods 0.000 description 9
- 238000000034 method Methods 0.000 description 9
- 239000013307 optical fiber Substances 0.000 description 6
- 230000003287 optical effect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000010295 mobile communication Methods 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/40—Bus networks
- H04L12/407—Bus networks with decentralised control
- H04L12/413—Bus networks with decentralised control with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
Landscapes
- Small-Scale Networks (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
Description
〔発明の属する技術分野〕
本発明は光フアイバ通信、同軸ケーブル通信、
衛星通信、移動無線通信等に適用することがで
き、複数の局が一つの伝送路あるいは媒体を共有
して相互に通信を行う通信方式に関する。特に、
複数の局が同時に一つの伝送路に送信信号を送出
し、その伝送路で信号衝突が生じていることを検
出する方式に関する。
〔従来技術の説明〕
光フアイバ通信、衛星通信、移動無線通信等で
は、一つの伝送路を複数の送受可能な局が共有し
て相互に通信を行う方式が広く利用されている。
この一つの例として、コンテンシヨン方式のマル
チアクセスを使うETHERNET(イーザネツト)
を例示して説明する。
第1図にイーザネツトの構成例を示す。一本の
同軸ケーブル1は共通の伝送路であつて、この同
軸ケーブル1には複数の局2-1〜2-oがそれぞれ
アダプタ3を介して結合されている。各局2-1〜
2-oには、端末装置5、インタフエース回路6、
送受信回路7を備え、放送形式のパケツトを送信
し、また自分あてのアドレスが付加されたパケツ
トを取り込む。同軸ケーブル1の両端にはケーブ
ル終端部9が設けられている。
それぞれの局は任意の時刻に自局の信号を送出
できる。したがつて、同時に複数の局から信号が
送出された場合には、伝送路上で信号の衝突が起
こり正しい情報を通信することができなくなる。
衝突が起きた場合には、誤まつた信号により伝送
路が占有されるので、ただちに衝突の検出ができ
るか否かは、この方式の伝送路の使用効率を大き
く左右する。したがつてこのようなコンランシヨ
ン方式のマルチアクセスには、衝突検出方式が必
須となる。
第2図にイーザネツトの衝突検出回路の構成例
を示す。これは米国特許第4063220号に開示され
た方式であつて、第2図は送受信回路7の要部構
成図である。端子Sの送信信号は送信回路11か
らアダプタ3へ送られ、受信信号は、アダプタ3
から受信回路12で受信復調されて端子Rへ現わ
れる。この端子Sの信号と端子Rの信号は、この
局1個のみが送信しているときには当然一致して
いるはずであり、この一致を排他論理和回路13
により識別する。遅延回路14は送信回路11、
受信回路12およびアダプタ3までのケーブルの
遅延量を補償するために挿入される。
この方式では、自局の送信時に自局の送信した
信号以外の信号が受信されると、送信信号と受信
信号が不一致になつて排他論理和回路13に出力
が生じるので、端子Dに信号が現われるときに
は、自局以外にも同軸ケーブル1に信号を送信し
ている局があることを識別する。
この方式は信号の伝送速度が小さく、局2から
同軸ケーブル1までの距離が短いときには有効な
方式であるが、伝送速度が大きくなり、あるいは
局2から同軸ケーブル1までの距離が大きいとき
は、遅延回路14の設定が適当に行われないと一
致を検出することが困難になり、誤検出が生じる
欠点がある。これを避けるため全ての局2-1〜2
−oでは、それぞれの局の条件に応じて異なる遅延
回路14を設ける必要があり、装置の種類が統一
でなくなるとともに、その調節には大きい工数を
要する。
〔発明の目的〕
本発明はこれを改良するもので、伝送速度が大
きい場合にも有効であり、自局の送信信号が受信
されるまでの遅延時間の大小にかかわらず、統一
的な装置で信号衝突を検出することができる方式
を提供することを目的とする。
〔本発明の要点〕
本発明は、送信信号を一定の符号則に基く冗長
符号により符号化して送信し、伝送路から受信さ
れる受信符号が、この一定の符号則を満足するか
否か検出することを特徴とする。
〔実施例による説明〕
第3図は本発明を実施する光通信方式の構成図
である。この通信方式そのものは公知の方式であ
り、例えば次の文献にも詳しい記載がある。
文献1
E.G.Rawson、R.M.Metcalfe:Fibernet
Multimode Optical Fiber for Local
Computer Network、IEEE、Trans.Com.
COM−26、7、1978pp983〜990
この方式は、1個の共通の伝送路1として光ミ
キサを用い、この伝送路1にそれぞれ光フアイバ
21,22により複数の局2-1〜2-oを接続す
る。第3図ではこの複数の局は2個のみを示す。
各局2-1〜2-oには、それぞれ光信号を送受する
送受信回路7、インタフエース回路、端末装置5
を含む。
第3図に示す方式では、1つの局、例えば局2
-1から送信された信号は他の全ての局2-2〜2-o
で受信することができる。また任意の1つの局で
は他の全ての局から伝送路1に送信された信号を
受信することができる。
本発明の特徴の1つは、複数の局2-1〜2-oか
ら共通の伝送路1に送信する信号に一定に符号則
に基く冗長符号を使用するところにある。その1
つの例はCMI(code mark inversion)符号であ
る。この符号則については、例えば
文献2
電子通信学会発行
「光フアイバ伝送」
昭和53年12月15日初版
に詳しい記述があるので、ここでは詳しい説明を
省略するが、伝送符号として「0」または「1」
が連続することのないように冗長性を持たせて定
められた符号則であるCMI符号変換則の一例を
表に示す。
[Technical field to which the invention pertains] The present invention relates to optical fiber communication, coaxial cable communication,
It can be applied to satellite communications, mobile radio communications, etc., and relates to a communication method in which multiple stations share one transmission path or medium to communicate with each other. especially,
The present invention relates to a method in which multiple stations simultaneously send out transmission signals on one transmission path and detect that a signal collision has occurred on that transmission path. [Description of the Prior Art] In optical fiber communications, satellite communications, mobile radio communications, etc., systems are widely used in which a single transmission path is shared by a plurality of stations capable of transmitting and receiving information to communicate with each other.
One example of this is ETHERNET, which uses contention-based multi-access.
will be explained using an example. FIG. 1 shows an example of the configuration of an Ethernet. One coaxial cable 1 is a common transmission path, and a plurality of stations 2 -1 to 2 -o are connected to this coaxial cable 1 via adapters 3, respectively. Each station 2 -1 ~
2 -o includes a terminal device 5, an interface circuit 6,
It is equipped with a transmitting/receiving circuit 7, and transmits packets in broadcast format, and also receives packets to which an address addressed to itself is added. Cable termination portions 9 are provided at both ends of the coaxial cable 1. Each station can transmit its own signal at any time. Therefore, when signals are sent from multiple stations at the same time, signal collision occurs on the transmission path, making it impossible to communicate correct information.
When a collision occurs, the transmission line is occupied by the erroneous signal, so whether or not the collision can be detected immediately has a large effect on the efficiency with which the transmission line is used in this system. Therefore, a collision detection method is essential for such collision-based multiple access. FIG. 2 shows an example of the configuration of an Ethernet collision detection circuit. This is a system disclosed in US Pat. No. 4,063,220, and FIG. 2 is a block diagram of the main part of the transmitting/receiving circuit 7. The transmission signal of the terminal S is sent from the transmission circuit 11 to the adapter 3, and the reception signal is sent to the adapter 3.
The signal is then received and demodulated by the receiving circuit 12 and appears at the terminal R. The signal at terminal S and the signal at terminal R should naturally match when only this one station is transmitting, and this match is determined by the exclusive OR circuit 13.
Identification by The delay circuit 14 is the transmitting circuit 11,
It is inserted to compensate for the amount of cable delay between the receiving circuit 12 and the adapter 3. In this method, if a signal other than the signal transmitted by the own station is received during transmission by the own station, the transmitted signal and the received signal will become inconsistent and an output will be generated in the exclusive OR circuit 13, so that the signal will be sent to terminal D. When it appears, it is recognized that there is a station other than the own station that is transmitting a signal to the coaxial cable 1. This method is effective when the signal transmission speed is low and the distance from station 2 to coaxial cable 1 is short, but when the transmission speed increases or the distance from station 2 to coaxial cable 1 is long, If the delay circuit 14 is not set appropriately, it will be difficult to detect a match, resulting in false detection. To avoid this, all stations 2 -1 ~ 2
In -o , it is necessary to provide different delay circuits 14 depending on the conditions of each station, and the types of devices are no longer unified, and its adjustment requires a large number of man-hours. [Purpose of the Invention] The present invention improves this and is effective even when the transmission speed is high, and it is possible to use a unified device regardless of the delay time until the transmission signal from the own station is received. The objective is to provide a method capable of detecting signal collisions. [Main points of the present invention] The present invention encodes and transmits a transmission signal using a redundant code based on a certain code rule, and detects whether a received code received from a transmission path satisfies this certain code rule. It is characterized by [Description by Example] FIG. 3 is a block diagram of an optical communication system implementing the present invention. This communication method itself is a well-known method, and is described in detail in the following literature, for example. Reference 1 EGRawson, RMMetcalfe: Fibernet
Multimode Optical Fiber for Local
Computer Network, IEEE, Trans.Com.
COM-26, 7, 1978 pp983-990 This system uses an optical mixer as one common transmission line 1, and connects a plurality of stations 2-1 to 2 -o to this transmission line 1 through optical fibers 21 and 22, respectively. Connecting. In FIG. 3, only two of the plurality of stations are shown.
Each station 2-1 to 2 -o includes a transmitting/receiving circuit 7 for transmitting and receiving optical signals, an interface circuit, and a terminal device 5.
including. In the system shown in Figure 3, one station, for example station 2,
The signal sent from -1 is transmitted to all other stations 2 -2 ~ 2 -o
can be received at Further, any one station can receive signals transmitted to the transmission line 1 from all other stations. One of the features of the present invention is that a redundant code based on a code rule is constantly used for signals transmitted from a plurality of stations 2 -1 to 2 -o to a common transmission path 1. Part 1
One example is a CMI (code mark inversion) code. This code rule is described in detail in, for example, Document 2, "Optical Fiber Transmission," published by the Institute of Electronics and Communication Engineers, December 15, 1973, first edition, so a detailed explanation is omitted here, but the transmission code is "0" or "1"
An example of the CMI code conversion rule is shown in the table below, which is a code rule that is set with redundancy so that the numbers are not consecutive.
上記例では光フアイバ通信の例を説明したが、
これ以外にも本発明の方式は衛星通信、移動通信
もしくは同軸通信方式等に応用できる。
上記例はCMI符号則を例にとつて説明した。
しかし、この符号則はどのような冗長符号則でも
よい。その符号則に応じて、その符号則を満足す
るか否かの回路を構成することができる。この符
号則の他の例としては、一般にmBnB符号を言わ
れる符号則が適当である。その中でもバイフエー
ズ符号、DMI(Differential mark inversion)符
号、AMI符号などを用いることができる。これ
らの符号則およびその性質については前記文献2
に詳しい記載がある。また、現在公知でない符号
則を用いるならば、受信符号がその符号則を満足
するか否かを検出する手段が得られれば、同様に
本発明を実施することができる。
〔効果の説明〕
以上説明したように、本発明では自局の送信信
号が再びその局に受信されるまでの時間の長さに
かかわらず複数局から同時に送出された信号の衝
突を検出できる方式が得られる。本発明の方式
は、各局に同一の装置を配置することができ、各
局毎に調整を行う必要がないので、装置がきわめ
て経済化できる利点がある。
In the above example, we explained an example of optical fiber communication.
In addition to this, the system of the present invention can be applied to satellite communications, mobile communications, coaxial communications systems, etc. The above example was explained using the CMI sign rule as an example.
However, this sign rule may be any redundant sign rule. Depending on the sign rule, it is possible to configure a circuit that satisfies the sign rule or not. As another example of this coding rule, the coding rule generally referred to as mBnB code is suitable. Among these, biphase codes, DMI (differential mark inversion) codes, AMI codes, etc. can be used. Regarding these sign rules and their properties, see the above document 2.
There is a detailed description. Furthermore, if a code rule that is not currently known is used, the present invention can be similarly implemented if a means for detecting whether the received code satisfies the code rule is available. [Explanation of Effects] As explained above, the present invention provides a method that can detect collisions of signals transmitted simultaneously from multiple stations, regardless of the length of time until the transmitted signal from one's own station is received by that station again. is obtained. The method of the present invention has the advantage that the same device can be placed in each station and there is no need to make adjustments for each station, making the device extremely economical.
第1図はイーザネツト形通信網の構成図。第2
図は従来例の衝突検出回路構成図。第3図は本発
明を実施した通信網の一構成例を示す図。第4図
は信号衝突した波形例を示す図。第5図は本発明
実施例光受信部の一構成例を示す図。第6図は本
発明の衝突検出部の一構成例を示す図。第7図は
衝突検出部タイミングチヤート。第8図は第6図
で示した衝突検出部を用いた実測結果を示す図。
FIG. 1 is a configuration diagram of an Ethernet type communication network. Second
The figure is a configuration diagram of a conventional collision detection circuit. FIG. 3 is a diagram showing an example of the configuration of a communication network in which the present invention is implemented. FIG. 4 is a diagram showing an example of waveforms caused by signal collision. FIG. 5 is a diagram showing an example of the configuration of an optical receiver according to an embodiment of the present invention. FIG. 6 is a diagram showing an example of the configuration of the collision detection section of the present invention. Figure 7 is a timing chart of the collision detection section. FIG. 8 is a diagram showing actual measurement results using the collision detection section shown in FIG. 6.
Claims (1)
と、 この複数の局のうちの一つの送信信号がこの局
以外の上記複数の局に受信されるように構成され
た伝送路と を含む通信方式において、 上記複数の局から上記伝送路に送信される送信
信号は、一定の符号則に基づく冗長符号により符
号化された信号であり、 上記伝送路から受信される信号を識別再生する
識別再生手段と、 この識別再生手段が出力する符号パターンが上
記一定の符号則に基づく符号パターンと比較して
その符号パターンと一致しているか否かを検出す
る衝突検出手段と、 この衝突検出手段で上記一定の符号則に基づく
符号パターンとの不一致が検出されたとき上記伝
送路において信号の衝突があると判定する手段と
を備えたことを特徴とする信号衝突検出方式。 2 信号の衝突を判定する手段は、信号衝突検出
手段で一定の符号則に基づく符号パターンとの不
一致が所定の割合を超えて検出されたときに伝送
路において信号の衝突があると判定する手段を含
むことを特徴とする特許請求の範囲第1項に記載
の信号衝突検出方式。[Claims] 1. A plurality of stations having a transmitting circuit and a receiving circuit, and a transmission line configured such that a transmission signal from one of the plurality of stations is received by the plurality of stations other than this station. In a communication system including the above, the transmission signals transmitted from the plurality of stations to the transmission path are signals encoded with redundant codes based on a certain coding rule, and the signals received from the transmission path are identified. an identification and reproduction means for reproducing; a collision detection means for comparing a code pattern outputted by the identification and reproduction means with a code pattern based on the certain code rule and detecting whether or not the code pattern matches the code pattern; A signal collision detection method comprising: means for determining that there is a signal collision in the transmission path when the detection means detects a mismatch with a code pattern based on the certain code rule. 2. The means for determining a signal collision is a means for determining that there is a signal collision in a transmission path when the signal collision detection means detects a mismatch with a code pattern based on a certain code rule in excess of a predetermined ratio. The signal collision detection method according to claim 1, characterized in that the signal collision detection method includes:
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP57136574A JPS5927640A (en) | 1982-08-04 | 1982-08-04 | Signal collision detecting system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP57136574A JPS5927640A (en) | 1982-08-04 | 1982-08-04 | Signal collision detecting system |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS5927640A JPS5927640A (en) | 1984-02-14 |
JPH0214823B2 true JPH0214823B2 (en) | 1990-04-10 |
Family
ID=15178445
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP57136574A Granted JPS5927640A (en) | 1982-08-04 | 1982-08-04 | Signal collision detecting system |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS5927640A (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS60174544A (en) * | 1984-02-21 | 1985-09-07 | Nec Corp | Detection system for signal collision |
JPS6249739A (en) * | 1985-08-29 | 1987-03-04 | Toshiba Corp | Star-coupler device |
JPH0638601B2 (en) * | 1985-11-13 | 1994-05-18 | 富士通株式会社 | Optical composite transceiver |
JP2502395B2 (en) * | 1990-02-09 | 1996-05-29 | 三菱電機株式会社 | Transceiver |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5890851A (en) * | 1981-11-26 | 1983-05-30 | Toshiba Corp | Detection system for collision of communication |
-
1982
- 1982-08-04 JP JP57136574A patent/JPS5927640A/en active Granted
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5890851A (en) * | 1981-11-26 | 1983-05-30 | Toshiba Corp | Detection system for collision of communication |
Also Published As
Publication number | Publication date |
---|---|
JPS5927640A (en) | 1984-02-14 |
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