Examples of Communication Systems/Further Developments of ISDN - Revision history

Guenter at 11:13, 10 November 2022

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Hwang at 09:54, 9 November 2022

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Guenter at 15:07, 27 October 2022

2022-10-27T15:07:24Z

@@ Line 62: / Line 62: @@
 In a fiber optic connection,&nbsp; the reference point between the network termination and the local exchange is referred to as&nbsp; $\rm U_{G2}$.&nbsp; This interface consists of two optical fibers for the two transmission directions.
-[[File:EN_Bei_T_1_4_S3.png|right|frame|Conversion from HDB3 to 1T2B code '''KORREKTUR: positive, negative, zero volt, undefined''']]
+[[File:EN_Bei_T_1_4_S3.png|right|frame|Conversion from HDB3 to 1T2B code <br>$11$: positive;&nbsp; $00$:  negative;&nbsp; $01$: zero volt;&nbsp; $10$: undefined''']]
 *Since it is not possible to transmit the ternary&nbsp; '''HDB3 code'''&nbsp; with the value set&nbsp; $\{–1, \ 0, +1\}$&nbsp; of the&nbsp; $\rm S_{2M}$ interface in optical form without a complex optical modulator,&nbsp; this must be converted back into a binary code with the elements&nbsp; $0$&nbsp; and&nbsp; $1$&nbsp; for the&nbsp; $\rm U_{G2}$ interface.

@@ Line 62: / Line 62: @@
 In a fiber optic connection,&nbsp; the reference point between the network termination and the local exchange is referred to as&nbsp; $\rm U_{G2}$.&nbsp; This interface consists of two optical fibers for the two transmission directions.
-[[File:EN_Bei_T_1_4_S3.png|right|frame|Conversion from HDB3 to 1T2B code]]
+[[File:EN_Bei_T_1_4_S3.png|right|frame|Conversion from HDB3 to 1T2B code '''KORREKTUR: positive, negative, zero volt, undefined''']]
 *Since it is not possible to transmit the ternary&nbsp; '''HDB3 code'''&nbsp; with the value set&nbsp; $\{–1, \ 0, +1\}$&nbsp; of the&nbsp; $\rm S_{2M}$ interface in optical form without a complex optical modulator,&nbsp; this must be converted back into a binary code with the elements&nbsp; $0$&nbsp; and&nbsp; $1$&nbsp; for the&nbsp; $\rm U_{G2}$ interface.

@@ Line 18: / Line 18: @@
 *The local and long-distance exchanges are specially designed for these large bandwidths.
-[[File:EN_Bei_T_1_4_S1.png|right|frame|Narrowband ISDN&nbsp; (below)&nbsp;and broadband ISDN&nbsp; (above)&nbsp;  in comparison '''Korrektur''']]
+[[File:EN_Bei_T_1_4_S1_neu.png|right|frame|Narrowband ISDN&nbsp; (below)&nbsp;and broadband ISDN&nbsp; (above)&nbsp;  in comparison]]
@@ Line 37: / Line 37: @@
 ==Fiber optic technology ==
 <br>
-[[File:EN_Bei_T_1_4_S2b.png|right|frame|E/O and O/E signal conversion '''Korrektur''']]
+[[File:EN_Bei_T_1_4_S2b_neu.png|right|frame|E/O and O/E signal conversion]]
 The transmission media used for broadband ISDN were&nbsp; '''fiber optic cables'''&nbsp; $\rm (FOC)$,&nbsp; often also referred to in simplified terms as&nbsp; "optical fibers".&nbsp;

@@ Line 49: / Line 49: @@
 #&nbsp; For comparison: &nbsp; For a copper cable with a diameter of 0.4 mm,&nbsp; the attenuation value for a DC signal is about&nbsp; $\text{5 dB/km}$&nbsp; and for a megahertz about&nbsp; $\text{20 dB/km}$&nbsp; – see section&nbsp; [[Examples_of_Communication_Systems/General_Description_of_ISDN#Attenuation_behavior_of_copper_cables|"Attenuation behavior of copper cables"]].<br>
 #&nbsp;Today&nbsp; (2018),&nbsp; optical fibers can achieve transmission rates of&nbsp; $\text{100 Gbit/s}$&nbsp;  and &ndash; with intermediate optical amplifiers &ndash;&nbsp; distances of several&nbsp; $\text{1000 km}$&nbsp; and more.&nbsp; Intermediate regenerators are now only used in exchanges,&nbsp; as the routing of data is still largely electronic.<br>
-#&nbsp; Current optical transmission systems transport data rates of&nbsp; $\text{100 Gbit/s}$&nbsp; over a distance of several&nbsp; $\text{1000 km}$ at a single wavelength.&nbsp; There are already&nbsp; (2018)&nbsp; systems commercially available at&nbsp; $\text{400 Gbit/s}$,&nbsp; but using multiple wavelengths.<br>v
+#&nbsp; Current optical transmission systems transport data rates of&nbsp; $\text{100 Gbit/s}$&nbsp; over a distance of several&nbsp; $\text{1000 km}$ at a single wavelength.&nbsp; There are already&nbsp; (2018)&nbsp; systems commercially available at&nbsp; $\text{400 Gbit/s}$,&nbsp; but using multiple wavelengths.<br>
-#&nbsp; "Optical&nbsp; '''W'''avelength&nbsp; '''D'''ivision&nbsp; '''M'''ultiplex"&nbsp; $\rm (WDM)$&nbsp; allows a large number of channels to be transmitted in parallel. In 2017, a total data rate of&nbsp; $\text{70.4 terabits/s}$&nbsp; was thus achieved via a transatlantic submarine cable&nbsp; $\rm (1 \ terabit = 10^{12} \ bits)$.<br>
+#&nbsp; "Optical&nbsp; '''W'''avelength&nbsp; '''D'''ivision&nbsp; '''M'''ultiplex"&nbsp; $\rm (WDM)$&nbsp; allows a large number of channels to be transmitted in parallel.&nbsp; In 2017,&nbsp; a total data rate of&nbsp; $\text{70.4 Tbits/s}$&nbsp; was thus achieved via one transatlantic submarine cable&nbsp; $\rm (1 \ Tbit = 10^{12} \ bits)$.<br>
-#&nbsp; Nowadays, fiber is mainly used between exchanges, while existing copper lines continue to be used between subscribers and exchanges for cost reasons. In the longer term, however, there will certainly be&nbsp; [https://en.wikipedia.org/wiki/Fiber-optic_communication ''Fiber–to–the–Home'']&nbsp; (FttH).
+#&nbsp; Nowadays,&nbsp; fiber is mainly used between exchanges,&nbsp; while existing copper lines continue to be used between subscribers and exchanges for cost reasons.&nbsp; In the longer term,&nbsp; however,&nbsp; there will certainly be&nbsp; [https://en.wikipedia.org/wiki/Fiber-optic_communication $\text{Fiber–to–the–Home}$]&nbsp; $\rm (FttH)$.
@@ Line 65: / Line 60: @@
 ==U<sub>G2</sub> interface==
 <br>
-In a fiber optic connection, the reference point between the network termination and the local exchange is referred to as&nbsp; $\rm U_{G2}$. This interface consists of two optical fibers for the two transmission directions.
+In a fiber optic connection,&nbsp; the reference point between the network termination and the local exchange is referred to as&nbsp; $\rm U_{G2}$.&nbsp; This interface consists of two optical fibers for the two transmission directions.
 [[File:EN_Bei_T_1_4_S3.png|right|frame|Conversion from HDB3 to 1T2B code]]
-*Since it is not possible to transmit the ternary HDB3 code with the value set&nbsp; $\{–1, \ 0, +1\}$&nbsp; of the&nbsp; $\rm S_{2M}$ interface in optical form without a complex optical modulator, this must be converted back into a binary code with the elements&nbsp; $0$&nbsp; and&nbsp; $1$&nbsp; for the&nbsp; $\rm U_{G2}$ interface.
+*Since it is not possible to transmit the ternary&nbsp; '''HDB3 code'''&nbsp; with the value set&nbsp; $\{–1, \ 0, +1\}$&nbsp; of the&nbsp; $\rm S_{2M}$ interface in optical form without a complex optical modulator,&nbsp; this must be converted back into a binary code with the elements&nbsp; $0$&nbsp; and&nbsp; $1$&nbsp; for the&nbsp; $\rm U_{G2}$ interface.
 This results in the following properties:
-*The conversion doubles the step rate to&nbsp; $\text{4096 kbit/s}$,&nbsp; which is in principle a disadvantage, but is more than compensated by the advantages of optical transmission.
+# &nbsp; The conversion doubles the step rate to&nbsp; $\text{4096 kbit/s}$,&nbsp; which is in principle a disadvantage,&nbsp; but is more than compensated by the advantages of optical transmission.
-*A real disadvantage is the additional effort required by the receiver to convert the optical signal into an electrical signal.
+# &nbsp; A real disadvantage is the additional effort required by the receiver to convert the optical signal into an electrical signal.
 ==ATM technology ==
 <br>
-Broadband ISDN is based on the so-called&nbsp; '''ATM technology'''&nbsp; (''''''A'''synchronous '''T'''ransfer '''M'''ode''). Compared with PCM 30, ATM offers the following advantages for broadband services and applications:
+Broadband ISDN is based on the so-called&nbsp; '''ATM technology'''&nbsp; $($'''A'''synchronous '''T'''ransfer '''M'''ode$)$.&nbsp; Compared with&nbsp; $\text{PCM 30}$,&nbsp; ATM offers the following advantages for broadband services and applications:
 [[File:EN_Bei_T_1_4_S2.png|right|frame|ATM cell structure]]
-*flexible access to the data,
+*Flexible access to the data,&nbsp; and
 *good adaptation to high bit rates.
-Here follows only a brief description of the&nbsp; [https://en.wikipedia.org/wiki/Asynchronous_Transfer_Mode "ATM method"]&nbsp; and how it works:
+Here follows only a brief description of the&nbsp; [https://en.wikipedia.org/wiki/Asynchronous_Transfer_Mode $\text{ATM method}$]&nbsp; and how it works:
 The cell header contains:
-*the ''Generic Flow Control'' (GFC) – 4 bits to control the cell flow,
+# &nbsp; the&nbsp;  "Generic Flow Control"&nbsp;  $\rm (GFC)$ &nbsp; &rArr;  &nbsp; $4$&nbsp; bits to control the cell flow,
-*the ''Virtual Path Identifier'' (VPI) – 8 bits for virtual path identification,
+# &nbsp; the&nbsp;  "Virtual Path Identifier"&nbsp;  $\rm (VPI)$&nbsp; &rArr;  &nbsp; $8$&nbsp; bits for virtual path identification,
-*the ''Virtual Channel Identifier'' (VCI) – 16 bits for virtual channel identification,
+# &nbsp; the&nbsp;  "Virtual Channel Identifier"&nbsp;  $\rm (VCI)$&nbsp; &rArr;  &nbsp; $16$&nbsp; bits for virtual channel identification,
-*the ''Payload Type'' (PT) – 3 bits to describe the cell type,
+# &nbsp; the&nbsp;  "Payload Type"&nbsp;  $\rm (PT)$&nbsp; &rArr;  &nbsp; $3$&nbsp; bits to describe the cell type,
-*the ''Cell Loss Priority'' (CLP) – one bit to detect a cell loss,
+# &nbsp; the&nbsp;  "Cell Loss Priority"&nbsp;  $\rm (CLP)$&nbsp; &rArr;  &nbsp; $1$&nbsp; bit to detect a cell loss,
-*the ''Header Error Control'' (HEC) – 8 bits to avoid bit errors in the cell header.
+# &nbsp; the&nbsp;  "Header Error Control"&nbsp;  $\rm (HEC)$&nbsp; &rArr;  &nbsp; $8$&nbsp; bits to avoid bit errors in the cell header.
-In ATM technology, cells arriving asynchronously from the terminals are transmitted using time division multiplexing. If no cells arrive, empty cells are generated so that there is always a continuous stream of cells on the line. ATM is asynchronous in the sense that cells with user information do not have to occur periodically.
+In ATM technology,&nbsp; cells arriving asynchronously from the terminals are transmitted using&nbsp; "Time Division Multiplexing".
-Further information on ATM can be found in the second main chapter&nbsp; [[Examples_of_Communication_Systems/xDSL_Systems|"DSL"]]  (''Digital Subscriber Line''), which also uses ATM technology.
+*Further information on ATM can be found in the second main chapter&nbsp; [[Examples_of_Communication_Systems/xDSL_Systems|$\rm DSL$]]&nbsp;  ("Digital Subscriber Line")&nbsp; in this book,&nbsp; which also uses ATM technology.

@@ Line 9: / Line 9: @@
 ==Broadband ISDN  ==
 <br>
-Broadband ISDN – usually abbreviated as&nbsp; $\text{B–ISDN}$&nbsp; – was a advancement of ISDN.&nbsp; The aim of this further development from 1996 was to enable new communications services with higher bandwidths in addition to the services and applications of narrowband ISDN.&nbsp; B-ISDN supports,&nbsp; for example,&nbsp; audiovisual services and multimedia applications such as video transmission,&nbsp; videophone and videoconferencing with transmission rates of up to a maximum of&nbsp; $155$&nbsp; Mbps.
+Broadband ISDN – usually abbreviated as&nbsp; $\text{B–ISDN}$&nbsp; – was a advancement of ISDN.&nbsp; The aim of this further development from 1996 was to enable new communications services with higher bandwidths in addition to the services and applications of narrowband ISDN.&nbsp; B-ISDN supports,&nbsp; for example,&nbsp; audiovisual services and multimedia applications such as video transmission,&nbsp; videophone and videoconferencing with transmission rates of up to a maximum of&nbsp; $\text{155 Mbps}$.
 To achieve such a large transmission rate,&nbsp; B-ISDN uses the following new technologies:
@@ Line 32: / Line 32: @@
 *The high costs are related to the fact that the optical fiber must be laid all the way to the subscriber.
-*However,&nbsp; larger&nbsp; (and therefore less flexible)&nbsp; companies and public authorities use B-ISDN for a longer time,&nbsp; with data rates of up to&nbsp; $622$&nbsp; Mbit/s being achieved after further modifications.
+*However,&nbsp; larger&nbsp; (and therefore less flexible)&nbsp; companies and public authorities use B-ISDN for a longer time,&nbsp; with data rates of up to&nbsp; $\text{622 Mbit/s}$&nbsp;  being achieved after further modifications.
 ==Fiber optic technology ==
 <br>
-The transmission media used for broadband ISDN were&nbsp; '''fiber optic cables'''&nbsp; $\rm (FOC)$,Broadband ISDN often also referred to in simplified terms as&nbsp; "optical fibers".&nbsp; Since the first attempts in the 1970s,&nbsp; optical transmission technology has made enormous progress and offers many advantages over electrical transmission:
+[[File:EN_Bei_T_1_4_S2b.png|right|frame|E/O and O/E signal conversion '''Korrektur''']]
-#&nbsp; In a fiber optic cable, signal propagation occurs through a guided electromagnetic field and there are no currents or voltages as in copper cables.&nbsp; A fiber optic cable is therefore "insensitive to electromagnetic noise"&nbsp; and is also much lighter than a copper cable.<br><br>
+The transmission media used for broadband ISDN were&nbsp; '''fiber optic cables'''&nbsp; $\rm (FOC)$,&nbsp; often also referred to in simplified terms as&nbsp; "optical fibers".&nbsp;
-*Today (2018), optical fibers can achieve transmission rates of&nbsp; $\text{100 Gbit/s}$&nbsp;  and &ndash; with intermediate optical amplifiers &ndash; distances of several&nbsp; $\text{1000 km}$&nbsp; and more. Intermediate regenerators are now only used in exchanges, as the routing of data is still largely electronic.
+*In the exchanges,&nbsp; electrical-to-optical conversion&nbsp; $\rm (E/O)$&nbsp; must be performed at the transmitting end by a&nbsp; "laser diode"&nbsp; $\rm (LD)$&nbsp; or a&nbsp; "light–emitting diode"&nbsp; $\rm (LED)$.
-*Current optical transmission systems transport data rates of&nbsp; $\text{100 Gbit/s}$&nbsp; over a distance of several&nbsp; $\text{1000 km}$ at a single wavelength. There are already (2018) systems commercially available at&nbsp; $\text{400 Gbit/s}$,&nbsp; but using multiple wavelengths.
+*At the receiver,&nbsp; an optical-electrical reconversion&nbsp; $\rm (O/E)$&nbsp; by a&nbsp; "photo diode" $\rm (PD)$&nbsp; is then necessary.&nbsp; In the sketch,&nbsp; "APD" stands for&nbsp; "avalanche photo diode".

@@ Line 9: / Line 9: @@
 ==Broadband ISDN  ==
 <br>
-Broadband ISDN – usually abbreviated as&nbsp; '''B–ISDN'''&nbsp; – was a further development of ISDN. The aim of this further development from 1996 was to enable new communications services with higher bandwidths in addition to the services and applications of narrowband ISDN. B-ISDN supports, for example, audiovisual services and multimedia applications such as video transmission, videophone and videoconferencing with transmission rates of up to a maximum of 155 Mbps.
+Broadband ISDN – usually abbreviated as&nbsp; $\text{B–ISDN}$&nbsp; – was a advancement of ISDN.&nbsp; The aim of this further development from 1996 was to enable new communications services with higher bandwidths in addition to the services and applications of narrowband ISDN.&nbsp; B-ISDN supports,&nbsp; for example,&nbsp; audiovisual services and multimedia applications such as video transmission,&nbsp; videophone and videoconferencing with transmission rates of up to a maximum of&nbsp; $155$&nbsp; Mbps.
 *The local and long-distance exchanges are specially designed for these large bandwidths.
 The graphic shows
-*below an ISDN network with two B channels (narrowband ISDN) via a copper twisted pair (Co–TP),
+*below an ISDN network with two bearer channels&nbsp; ("narrowband ISDN")&nbsp; via a copper twisted pair&nbsp; ("Co–TP"),
-*compared with broadband ISDN (B-ISDN) via optical fiber (FOC, fiber optic cable) at the top.
-Signaling takes place via another copper twisted pair (in the center).
-<br clear=all>
+Broadband ISDN failed to achieve great commercial success because this technology was very expensive and sufficient bandwidths could also be achieved with&nbsp; [[Examples_of_Communication_Systems/General_Description_of_DSL#.23_OVERVIEW_OF_THE_SECOND_MAIN_CHAPTER_.23|$\rm DSL$]]&nbsp; ("Digital Subscriber Line").
 *The high costs are related to the fact that the optical fiber must be laid all the way to the subscriber.
-*However, larger (and therefore less flexible) companies and public authorities still use B-ISDN in some cases today, with data rates of up to 622 Mbit/s being achieved after further modifications.
 ==Fiber optic technology ==
 <br>
-The transmission media used for B-ISDN were&nbsp; '''fiber optic cables'''&nbsp; (FOC), often also referred to in simplified terms as "optical fibers". Since the first attempts in the 1970s, optical transmission technology has made enormous progress and offers many advantages over electrical transmission:
+The transmission media used for broadband ISDN were&nbsp; '''fiber optic cables'''&nbsp; $\rm (FOC)$,Broadband ISDN often also referred to in simplified terms as&nbsp; "optical fibers".&nbsp; Since the first attempts in the 1970s,&nbsp; optical transmission technology has made enormous progress and offers many advantages over electrical transmission:
-*In a fiber optic cable, signal propagation occurs through a guided electromagnetic field and there are no currents or voltages as in copper cables. A fiber optic cable is therefore "''insensitive to electromagnetic noise''" and is also much lighter than a copper cable.
+#&nbsp; In a fiber optic cable, signal propagation occurs through a guided electromagnetic field and there are no currents or voltages as in copper cables.&nbsp; A fiber optic cable is therefore "insensitive to electromagnetic noise"&nbsp; and is also much lighter than a copper cable.<br><br>
-*The signal attenuation of an optical fiber is significantly lower than that of a copper cable. At the "''attenuation minimum''" at the wavelength&nbsp; $λ = 1.55 \ µ{\rm m}$,&nbsp; a value of&nbsp; $\text{0.2 dB/km}$&nbsp; is reached. For comparison: &nbsp; For a copper cable with a diameter of 0.4 mm, the attenuation value for a DC signal is about&nbsp; $\text{5 dB/km}$&nbsp; and for a megahertz about&nbsp; $\text{20 dB/km}$&nbsp; – see section&nbsp; [[Examples_of_Communication_Systems/General_Description_of_ISDN#Attenuation_behavior_of_copper_cables|"Attenuation behavior of copper cables"]].
+#&nbsp;The signal attenuation of an optical fiber is significantly lower than that of a copper cable. At the "''attenuation minimum''" at the wavelength&nbsp; $λ = 1.55 \ µ{\rm m}$,&nbsp; a value of&nbsp; $\text{0.2 dB/km}$&nbsp; is reached. For comparison: &nbsp; For a copper cable with a diameter of 0.4 mm, the attenuation value for a DC signal is about&nbsp; $\text{5 dB/km}$&nbsp; and for a megahertz about&nbsp; $\text{20 dB/km}$&nbsp; – see section&nbsp; [[Examples_of_Communication_Systems/General_Description_of_ISDN#Attenuation_behavior_of_copper_cables|"Attenuation behavior of copper cables"]].
 *Today (2018), optical fibers can achieve transmission rates of&nbsp; $\text{100 Gbit/s}$&nbsp;  and &ndash; with intermediate optical amplifiers &ndash; distances of several&nbsp; $\text{1000 km}$&nbsp; and more. Intermediate regenerators are now only used in exchanges, as the routing of data is still largely electronic.

@@ Line 46: / Line 46: @@
 [[File:EN_Bei_T_1_4_S2b.png|right|frame|E/O and O/E signal conversion]]
-<br>In den Vermittlungsstellen muss sendeseitig eine elektrisch–optische Wandlung (E/O) durch eine ''Laserdiode''&nbsp; (LD) oder eine LED (englisch: ''Light–emitting Diode'') vorgenommen werden.
+<br>In the exchanges, electrical-to-optical conversion (E/O) must be performed at the transmitting end by a ''laser diode''&nbsp; (LD) or an LED (''Light–emitting Diode'').
-Beim Empfänger ist dann eine optisch–elektrische Rückwandlung (O/E) durch eine ''Photodiode'' (PD) notwendig.
+At the receiver, an optical-electrical reconversion (O/E) by a ''photodiode'' (PD) is then necessary.
-''Hinweis'': &nbsp; "APD" steht für Lawinenphotodiode (englisch: &nbsp; ''Avalanche Photodiode'').
+''Note'': &nbsp; "APD" stands for avalanche photodiode.
@@ Line 60: / Line 60: @@
-==U<sub>G2</sub>–Schnittstelle==
+==U<sub>G2</sub> interface==
 <br>
-Bei einer Glasfaseranbindung bezeichnet man den Referenzpunkt zwischen Netzabschluss und Ortsvermittlungsstelle mit&nbsp; $\rm U_{G2}$. Diese Schnittstelle besteht aus zwei Glasfasern für die beiden Übertragungsrichtungen.
+In a fiber optic connection, the reference point between the network termination and the local exchange is referred to as&nbsp; $\rm U_{G2}$. This interface consists of two optical fibers for the two transmission directions.
-[[File:EN_Bei_T_1_4_S3.png|right|frame|Umsetzung vom HDB3- in den 1T2B–Code]]
+[[File:EN_Bei_T_1_4_S3.png|right|frame|Conversion from HDB3 to 1T2B code]]
-*Da man den ternären HDB3–Code mit dem Wertevorrat&nbsp; $\{–1, \ 0, +1\}$&nbsp; der&nbsp; $\rm S_{2M}$–Schnittstelle in optischer Form ohne aufwändigen optischen Modulator nicht übertragen kann, muss für die&nbsp; $\rm U_{G2}$–Schnittstelle dieser wieder in einen Binärcode mit den Elementen&nbsp; $0$&nbsp; und&nbsp; $1$&nbsp; gewandelt werden.
+*Since it is not possible to transmit the ternary HDB3 code with the value set&nbsp; $\{–1, \ 0, +1\}$&nbsp; of the&nbsp; $\rm S_{2M}$ interface in optical form without a complex optical modulator, this must be converted back into a binary code with the elements&nbsp; $0$&nbsp; and&nbsp; $1$&nbsp; for the&nbsp; $\rm U_{G2}$ interface.
-*Diese Umwandlung erfolgt redundant mit dem&nbsp; '''1T2B–Code'''. Das heißt:&nbsp; Jedes Ternärsymbol wird durch zwei Binärsymbole gemäß der angegebenen Tabelle dargestellt. Die Coderedundanz ist hierbei gleich&nbsp; $1 – \log_2 \hspace{0.05cm} (3)/2 ≈ 20.7\%$.
+*This conversion is done redundantly with the&nbsp; '''1T2B code'''. This means:&nbsp; Each ternary symbol is represented by two binary symbols according to the given table. The code redundancy here is equal to&nbsp; $1 – \log_2 \hspace{0.05cm} (3)/2 ≈ 20.7\%$.
 <br clear=all>
-Daraus ergeben sich folgende Eigenschaften:
+This results in the following properties:
-*Durch die Umsetzung wird die Schrittgeschwindigkeit auf&nbsp; $\text{4096 kbit/s}$&nbsp; verdoppelt, was prinzipiell von Nachteil ist, aber durch die Vorteile der optischen Übertragung mehr als ausgeglichen wird.
+*The conversion doubles the step rate to&nbsp; $\text{4096 kbit/s}$,&nbsp; which is in principle a disadvantage, but is more than compensated by the advantages of optical transmission.
-*Ein echter Nachteil ist der zusätzliche Aufwand des Empfängers für die Umsetzung des optischen Signals in ein elektrisches Signal.
+*A real disadvantage is the additional effort required by the receiver to convert the optical signal into an electrical signal.
-==ATM–Technik ==
+==ATM technology ==
 <br>
-Das Breitband–ISDN basiert auf der so genannten&nbsp; '''ATM–Technik'''&nbsp; (''''''A'''synchronous '''T'''ransfer '''M'''ode''). Gegenüber PCM 30 bietet ATM folgende Vorteile für Breitbanddienste und –Anwendungen:
+Broadband ISDN is based on the so-called&nbsp; '''ATM technology'''&nbsp; (''''''A'''synchronous '''T'''ransfer '''M'''ode''). Compared with PCM 30, ATM offers the following advantages for broadband services and applications:
-[[File:EN_Bei_T_1_4_S2.png|right|frame|ATM–Zellenstruktur]]
+[[File:EN_Bei_T_1_4_S2.png|right|frame|ATM cell structure]]
-*flexible Zugriffsmöglichkeiten auf die Daten,
+*flexible access to the data,
-*eine gute Anpassung an hohe Bitraten.
+*good adaptation to high bit rates.
-Hier folgt nur eine kurze Beschreibung des&nbsp; [https://de.wikipedia.org/wiki/Asynchronous_Transfer_Mode ATM–Verfahrens]&nbsp; und seiner Funktionsweise:
+Here follows only a brief description of the&nbsp; [https://en.wikipedia.org/wiki/Asynchronous_Transfer_Mode "ATM method"]&nbsp; and how it works:
-*ATM ist eine spezielle verbindungsorientierte Paketvermittlung, wobei die Pakete hier als ATM–Zellen bezeichnet werden.
+*ATM is a special connection-oriented packet switching, and the packets here are called ATM cells.
-*Es handelt es sich also um eine paketorientierte Übertragung von Zellen.
+*It is therefore a packet-oriented transmission of cells.
 <br clear=all>
-Die Grafik zeigt die ATM–Zellenstruktur. Jede ATM–Zelle setzt sich aus 53 Byte zusammen und besteht aus dem Zellenkopf (5 Byte) sowie einem Informationsfeld (48 Byte), das für die Übertragung von Nutzinformationen oder Signalisierungsdaten verwendet wird.
+Each ATM cell is composed of 53 bytes and consists of the cell header (5 bytes) and an information field (48 bytes), which is used for the transmission of user information or signaling data.
-Der Zellenkopf enthält:
+The cell header contains:
-*den ''Generic Flow Control'' (GFC) – 4 Bit zur Steuerung des Zellflusses,
+*the ''Generic Flow Control'' (GFC) – 4 bits to control the cell flow,
-*den ''Virtual Path Identifier'' (VPI) – 8 Bit zur virtuellen Pfadkennung,
+*the ''Virtual Path Identifier'' (VPI) – 8 bits for virtual path identification,
-*den ''Virtual Channel Identifier'' (VCI) – 16 Bit zur virtuellen Kanalkennzeichnung,
+*the ''Virtual Channel Identifier'' (VCI) – 16 bits for virtual channel identification,
-*den ''Payload Type'' (PT) – 3 Bit zur Beschreibung des Zellentyps,
+*the ''Payload Type'' (PT) – 3 bits to describe the cell type,
-*die ''Cell Loss Priority'' (CLP) – ein Bit, um einen Zellenverlust zu erkennen,
+*the ''Cell Loss Priority'' (CLP) – one bit to detect a cell loss,
-*den ''Header Error Control'' (HEC) – 8 Bit, um Bitfehler im Zellenkopf zu vermeiden.
+*the ''Header Error Control'' (HEC) – 8 bits to avoid bit errors in the cell header.
-Bei der ATM–Technik werden die von den Endgeräten asynchron ankommenden Zellen im Zeitmultiplexverfahren übertragen. Kommen keine Zellen an, so werden Leerzellen erzeugt, so dass auf der Leitung stets ein kontinuierlicher Zellenstrom vorliegt. ATM ist in dem Sinn asynchron, dass Zellen mit Nutzinformation nicht periodisch auftreten müssen.
+In ATM technology, cells arriving asynchronously from the terminals are transmitted using time division multiplexing. If no cells arrive, empty cells are generated so that there is always a continuous stream of cells on the line. ATM is asynchronous in the sense that cells with user information do not have to occur periodically.
-Weitere Informationen zu ATM finden Sie im zweiten Hauptkapitel&nbsp; [[Examples_of_Communication_Systems/xDSL–Systeme|DSL]]  (''Digital Subscriber Line''), das ebenfalls die ATM–Technik benutzt.
+Further information on ATM can be found in the second main chapter&nbsp; [[Examples_of_Communication_Systems/xDSL_Systems|"DSL"]]  (''Digital Subscriber Line''), which also uses ATM technology.
-==Aufgabe zum Kapitel ==
+==Exercise for the chapter ==
 <br>
-[[Aufgaben:Aufgabe_1.7:_Codierung_bei_B–ISDN|Aufgabe 1.7: Codierung bei B–ISDN]]
+[[Aufgaben:Exercise_1.7:_Coding_for_B-ISDN|Exercise 1.7: Coding for B-ISDN]]

@@ Line 40: / Line 40: @@
 *Current optical transmission systems transport data rates of&nbsp; $\text{100 Gbit/s}$&nbsp; over a distance of several&nbsp; $\text{1000 km}$ at a single wavelength. There are already (2018) systems commercially available at&nbsp; $\text{400 Gbit/s}$,&nbsp; but using multiple wavelengths.
-*&nbsp; '''Optical ''W''avelength ''D''ivision ''M''ultiplex'''&nbsp; (WDM)&nbsp; können eine Vielzahl von Kanälen parallel übertragen werden.  Damit wurde im Jahr 2017 über ein Transatlantik&ndash;Unterseekabel eine Gesamt-Datenrate von&nbsp; $\text{70.4 Terabit/s}$&nbsp;  erreicht&nbsp; $\rm (1 \ Terabit = 10^{12} \ bit)$.
+*&nbsp; '''Optical ''W''avelength ''D''ivision ''M''ultiplex'''&nbsp; (WDM)&nbsp; allows a large number of channels to be transmitted in parallel. In 2017, a total data rate of&nbsp; $\text{70.4 terabits/s}$&nbsp; was thus achieved via a transatlantic submarine cable&nbsp; $\rm (1 \ terabit = 10^{12} \ bits)$.
-*Heutzutage werden Glasfasern vorwiegend zwischen den Vermittlungsstellen eingesetzt, während man aus Kostengründen zwischen Teilnehmer und Vermittlungsstelle weiterhin die vorhandenen Kupferleitungen verwendet. Längerfristig wird es aber sicher&nbsp; [https://de.wikipedia.org/wiki/Glasfasernetz ''Fiber–to–the–Home'']&nbsp; (FttH) geben.
+*Nowadays, fiber is mainly used between exchanges, while existing copper lines continue to be used between subscribers and exchanges for cost reasons. In the longer term, however, there will certainly be&nbsp; [https://en.wikipedia.org/wiki/Fiber-optic_communication ''Fiber–to–the–Home'']&nbsp; (FttH).
-[[File:EN_Bei_T_1_4_S2b.png|right|frame|E/O– und O/E–Signalwandlung]]
+[[File:EN_Bei_T_1_4_S2b.png|right|frame|E/O and O/E signal conversion]]
 <br>In den Vermittlungsstellen muss sendeseitig eine elektrisch–optische Wandlung (E/O) durch eine ''Laserdiode''&nbsp; (LD) oder eine LED (englisch: ''Light–emitting Diode'') vorgenommen werden.

@@ Line 7: / Line 7: @@
-==Breitband–ISDN  ==
+==Broadband ISDN  ==
 <br>
-Breitband–ISDN – meist abgekürzt als&nbsp; '''B–ISDN'''&nbsp; – war eine Weiterentwicklung von ISDN. Ziel dieser Weiterentwicklung aus dem Jahre 1996 war es, zusätzlich zu den Diensten und Anwendungen des Schmalband–ISDN neue Kommunikationsdienste mit höheren Bandbreiten zu ermöglichen. B–ISDN unterstützt beispielsweise audiovisuelle Dienste und Multimedia–Anwendungen wie Bildübertragung, Bildtelefon und Videokonferenz mit Übertragungsraten bis zu maximal 155 Mbit/s.
+Broadband ISDN – usually abbreviated as&nbsp; '''B–ISDN'''&nbsp; – was a further development of ISDN. The aim of this further development from 1996 was to enable new communications services with higher bandwidths in addition to the services and applications of narrowband ISDN. B-ISDN supports, for example, audiovisual services and multimedia applications such as video transmission, videophone and videoconferencing with transmission rates of up to a maximum of 155 Mbps.
-Um eine solch große Übertragungsrate zu erreichen, nutzt B–ISDN folgende neue Technologien:
+To achieve such a large transmission rate, B-ISDN uses the following new technologies:
-*Anstelle von Kupferkabeln werden Glasfasern verwendet, die aufgrund ihrer geringen Dämpfung größere Bandbreiten und Reichweiten ermöglichen. Auf der nächsten Seite sind die Vorteile der&nbsp; '''Glasfasertechnologie'''&nbsp; zusammengestellt.
+*Instead of copper cables, optical fibers are used, which enable greater bandwidths and ranges due to their low attenuation. The advantages of&nbsp; '''fiber optic technology'''&nbsp; are summarized in the next section.
-*Zur Übertragung und Vermittlung der Information wird auf die&nbsp; '''ATM–Technik'''&nbsp; ('''''A'''synchronous '''T'''ransfer '''M'''ode'')&nbsp; gesetzt. Auf der letzten Seite dieses Abschnitts wird diese Übertragungstechnik für Breitband–ISDN erklärt.
+*&nbsp; '''ATM technology'''&nbsp; ('''''A'''synchronous '''T'''ransfer '''M'''ode'')&nbsp; is used to transmit and switch the information. The last section explains this transmission technology for broadband ISDN.
-*Die Orts– und Fernvermittlungsstellen sind speziell für diese großen Bandbreiten ausgelegt.
+*The local and long-distance exchanges are specially designed for these large bandwidths.
-[[File:EN_Bei_T_1_4_S1.png|right|frame|Schmalband–ISDN und Breitband–ISDN im Vergleich]]
+[[File:EN_Bei_T_1_4_S1.png|right|frame|Narrowband ISDN and broadband ISDN in comparison]]
-Die Grafik zeigt
+The graphic shows
-*unten ein ISDN–Netz mit zwei B–Kanälen (Schmalband–ISDN) über eine Kupfer–Doppelader (Cu–DA),
+*below an ISDN network with two B channels (narrowband ISDN) via a copper twisted pair (Co–TP),
-*oben im Vergleich das Breitband–ISDN (B–ISDN) über Glasfaser (LWL, Lichtwellenleiter).
+*compared with broadband ISDN (B-ISDN) via optical fiber (FOC, fiber optic cable) at the top.
-Über eine weitere Kupfer–Doppelader (in der Mitte) erfolgt die Signalisierung.
+Signaling takes place via another copper twisted pair (in the center).
 <br clear=all>
-Der große wirtschaftliche Erfolg von Breitband–ISDN ist ausgeblieben, da diese Technologie sehr teuer war und mit&nbsp; [[Examples_of_Communication_Systems/Allgemeine_Beschreibung_von_DSL#.23_.C3.9CBERBLICK_ZUM_ZWEITEN_HAUPTKAPITEL_.23|DSL]]&nbsp; (''Digital Subscriber Line'') ebenfalls ausreichende Bandbreiten erreicht werden konnten.
+Broadband ISDN failed to achieve great commercial success because this technology was very expensive and sufficient bandwidths could also be achieved with&nbsp; [[Examples_of_Communication_Systems/General_Description_of_DSL#.23_OVERVIEW_OF_THE_SECOND_MAIN_CHAPTER_.23|"DSL"]]&nbsp; (''Digital Subscriber Line'').
-*Die hohen Kosten hängen damit zusammen, dass die Glasfaser bis zum Teilnehmer verlegt werden muss.
+*The high costs are related to the fact that the optical fiber must be laid all the way to the subscriber.
-*Größere (und deshalb weniger flexible) Firmen und Behörden benutzen aber teilweise auch heute noch B–ISDN, wobei nach weiteren Modifikationen Datenraten bis zu 622 Mbit/s erreicht werden.
+*However, larger (and therefore less flexible) companies and public authorities still use B-ISDN in some cases today, with data rates of up to 622 Mbit/s being achieved after further modifications.
-==Glasfasertechnologie ==
+==Fiber optic technology ==
 <br>
-Als Übertragungsmedien für B–ISDN wurden&nbsp; '''Lichtwellenleiter'''&nbsp; (LWL) verwendet, häufig auch vereinfacht "Glasfasern" genannt. Seit den ersten Versuchen in den 1970er Jahren hat die optische Übertragungstechnik enorme Fortschritte gemacht und bietet viele Vorteile gegenüber der elektrischen Übertragung:
+The transmission media used for B-ISDN were&nbsp; '''fiber optic cables'''&nbsp; (FOC), often also referred to in simplified terms as "optical fibers". Since the first attempts in the 1970s, optical transmission technology has made enormous progress and offers many advantages over electrical transmission:
-*In einem Lichtwellenleiter erfolgt die Signalausbreitung durch ein geführtes elektromagnetisches Feld und es existieren keine Ströme und Spannungen wie bei Kupferleitungen. Ein Glasfaserkabel ist deshalb ''unempfindlich gegenüber elektromagnetischen Störungen''" und zudem wesentlich leichter als ein Kupferkabel.
+*In a fiber optic cable, signal propagation occurs through a guided electromagnetic field and there are no currents or voltages as in copper cables. A fiber optic cable is therefore "''insensitive to electromagnetic noise''" and is also much lighter than a copper cable.
-*Die Signaldämpfung eines Lichtwellenleiters ist deutlich geringer als die eines Kupferkabels. Im ''Dämpfungsminimum'' " bei der Wellenlänge&nbsp; $λ = 1.55 \ µ{\rm m}$&nbsp; wird ein Wert von&nbsp; $\text{0.2 dB/km}$&nbsp; erreicht. Zum Vergleich: &nbsp; Bei einer Kupferleitung mit 0.4 mm Durchmesser beträgt der Dämpfungswert für ein Gleichsignal ca.&nbsp; $\text{5 dB/km}$&nbsp; und bei einem Megahertz etwa&nbsp; $\text{20 dB/km}$&nbsp; – siehe Abschnitt&nbsp; [[Examples_of_Communication_Systems/Allgemeine_Beschreibung_von_ISDN#D.C3.A4mpfungsverhalten_von_Kupferkabeln|Dämpfungsverhalten von Kupferkabeln]].
+*The signal attenuation of an optical fiber is significantly lower than that of a copper cable. At the "''attenuation minimum''" at the wavelength&nbsp; $λ = 1.55 \ µ{\rm m}$,&nbsp; a value of&nbsp; $\text{0.2 dB/km}$&nbsp; is reached. For comparison: &nbsp; For a copper cable with a diameter of 0.4 mm, the attenuation value for a DC signal is about&nbsp; $\text{5 dB/km}$&nbsp; and for a megahertz about&nbsp; $\text{20 dB/km}$&nbsp; – see section&nbsp; [[Examples_of_Communication_Systems/General_Description_of_ISDN#Attenuation_behavior_of_copper_cables|"Attenuation behavior of copper cables"]].
-*Mit Glasfasern kann man heute (2018) Übertragungsraten von&nbsp; $\text{100 Gbit/s}$&nbsp;  und &ndash; mit zwischengeschalteten optischen Verstärkern &ndash; Entfernungen von mehreren&nbsp; $\text{1000 km}$&nbsp; und mehr erreichen. Zwischenregeneratoren werden nur noch in Vermittlungsstellen eingesetzt, da das Routing der Daten immer noch weitgehend elektronisch erfolgt.
+*Today (2018), optical fibers can achieve transmission rates of&nbsp; $\text{100 Gbit/s}$&nbsp;  and &ndash; with intermediate optical amplifiers &ndash; distances of several&nbsp; $\text{1000 km}$&nbsp; and more. Intermediate regenerators are now only used in exchanges, as the routing of data is still largely electronic.
-*Aktuelle optische Übertragungssysteme transportieren bei einer einzigen Wellenlänge Datenraten von&nbsp; $\text{100 Gbit/s}$&nbsp; über eine Entfernung von mehreren&nbsp; $\text{1000 km}$. Es sind bereits heute (2018) Systeme mit&nbsp; $\text{400 Gbit/s}$&nbsp; kommerziell erhältlich, allerdings unter Verwendung mehrerer Wellenlängen.
+*Current optical transmission systems transport data rates of&nbsp; $\text{100 Gbit/s}$&nbsp; over a distance of several&nbsp; $\text{1000 km}$ at a single wavelength. There are already (2018) systems commercially available at&nbsp; $\text{400 Gbit/s}$,&nbsp; but using multiple wavelengths.
-*Durch&nbsp; '''optisches Wellenlängenmultiplex'''&nbsp; (englisch:&nbsp; '''''W'''avelength '''D'''ivision '''M'''ultiplex'', WDM)&nbsp; können eine Vielzahl von Kanälen parallel übertragen werden.  Damit wurde im Jahr 2017 über ein Transatlantik&ndash;Unterseekabel eine Gesamt-Datenrate von&nbsp; $\text{70.4 Terabit/s}$&nbsp;  erreicht&nbsp; $\rm (1 \ Terabit = 10^{12} \ bit)$.
+*&nbsp; '''Optical ''W''avelength ''D''ivision ''M''ultiplex'''&nbsp; (WDM)&nbsp; können eine Vielzahl von Kanälen parallel übertragen werden.  Damit wurde im Jahr 2017 über ein Transatlantik&ndash;Unterseekabel eine Gesamt-Datenrate von&nbsp; $\text{70.4 Terabit/s}$&nbsp;  erreicht&nbsp; $\rm (1 \ Terabit = 10^{12} \ bit)$.
 *Heutzutage werden Glasfasern vorwiegend zwischen den Vermittlungsstellen eingesetzt, während man aus Kostengründen zwischen Teilnehmer und Vermittlungsstelle weiterhin die vorhandenen Kupferleitungen verwendet. Längerfristig wird es aber sicher&nbsp; [https://de.wikipedia.org/wiki/Glasfasernetz ''Fiber–to–the–Home'']&nbsp; (FttH) geben.