Ericsson RBS 2106 Hardware Reference Manual page 397

RBS 2000
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EN/LZT 720 0283 Uen R1A
Joint Technical Committee
Link Access Procedures on D-channel
LAPD is the data link layer (layer 2) protocol used for
communication between the BSC and the BTS on the
Abis interface.
Abis layer 2 is sometimes used synonymously with
LAPD.
Line Build Out
Light Emitting Diode
Line Loop Back
Low Noise Amplifier
The local bus offers communication between a central
main RU (DXU) and distributed main RUs (TRU and
ECU).
When the RU is in Local mode, it is not communicating
with the BSC.
A switch used by the operator to order the RU to enter
Local or Remote mode.
Loss Of Frame
A logical channel represents a specified portion of the
information carrying capacity of a physical channel.
GSM defines two major categories of logical channels:
• TCHs – Traffic CHannels, for speech or user data
• CCHs – Control CHannels, for control signalling
⇒ Physical Channel ⇒ Channel Combination
A unit which can be referred to, but is not a single
physical unit. There are three different kinds of logical
RUs:
• Antennas
• Buses
• Environment
Glossary
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