Basic Node
3.4.2.2.5 Line Interface
This block provides the E1 line interfaces for external connection.
3.5 STM-1 Interface
The LTU 155 plug-in units provide a channeled STM-1 Terminal Multiplexer
(TM) interface. This interface terminates one STM-1 with 63xE1 (or 21xE1)
mapped asynchronously into 63xVC-12 (or 21xVC-12), depending on the type
of plug-in unit. The E1s are available at the TDM bus for traffic routing to other
plug-in units.
If incoming SDH radio traffic on MMU2 E/F 155 shall be connected to the TDM
bus, an LTU 155 is needed as a terminal multiplexer to extract the E1s from the
STM-1. See Section 4.2 on page 61.
3.5.1 Overview
• At aggregation sites where the high capacity optical network connects to
the microwave network. The LTU 155 provides an effective interface using
one STM-1 interconnection instead of nxE1.
• To build high capacity microwave networks, with for example ring topology,
using a combination of MINI-LINK TN’s.
• Transmission of up to 21xE1 over channelized STM-1 interfacing 3G radio
base stations.
Both electrical and optical interfaces are available.
The STM-1 interface on LTU 155s can be equipment and line protected using
MSP 1+1, see Section 3.9.3 on page 48.
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4/1555-CSH 109 32/1-V1 Uen B 2007-09-14
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