U K0 interface
The U K0 interface is at the ISDN - basic access the interface for the transmission path between the switching network node (VNk) and NT and is formed by two copper wires (one wire pair realized). The U in the designation represents the reference point of the interface in the ISDN reference model (see illustration), the K stands for K upfer and the zero refers to the ISDN basic access ( "Basic Rate Interface"; BRI).
The ternary line code 4B3T with a step speed of 120 kBaud or the 2B1Q line code (step speed 80 kBaud ) is used as coding . In Germany, 4B3T (= MMS43 code ) is used as the line code, the standardization organization European Institute for Telecommunications Standards (ETSI) provides 2B1Q as the standard with an option to also use 4B3T .
In order to enable simultaneous transmission on one pair of wires in both directions, a transmission method with echo compensation in the same time and frequency is used.
In addition to the user channels ( B channels ) and the signaling channel ( D channel ), the network operator also has a channel for service purposes (in the technical jargon maintenance ). For example, control signals for loop commands can be transmitted from the local exchange via the U K0 interface to the NTBA, which loop back the signal sent to the NTBA to the OVSt. This enables the VNk to check whether the NTBA is working and to measure the quality of the line ( traffic quality , bit error frequency ) on the basis of bit errors that have occurred .
Interface data
- Frequency equalization method with hybrid circuit and echo compensation
- 2 user channels ( B channels ) each 64 kbit / s duplex
- 1 signaling channel ( D-channel ) 16 kbit / s
- Frame identification (synchronization) and service 16 kbit / s
- Gross data transfer rate 160 kbit / s
- Symbol rate 120 k baud through MMS43 code
- Reach <6 km to 0.4 mm Cu - wire pairs and <8 km to 0.6 mm copper wire pairs
- 91-99 V DC
literature
- Martin Werner: communications engineering. 7th edition, Vieweg + Teubner, Wiesbaden 2010, ISBN 978-3-8348-0905-6 .
- Rudolf Nocker: Digital Communication Systems 2nd 1st edition, Friedrich Vieweg & Sohn Verlag, Wiesbaden 2005, ISBN 978-3-528-03977-6 .
- Andres Keller: Broadband cables and access networks. Technical principles and standards, Springer-Verlag, Berlin / Heidelberg 2011, ISBN 978-3-642-17631-9 .
Individual evidence
- ↑ ETSI TS 102 080 Transmission and Multiplexing (TM); Integrated Services Digital Network (ISDN) basic rate access; Digital transmission system on metallic local lines.