Reference Manual

RBS 2000 Glossary
-7&
Joint Technical Committee
/$3' Link Access Procedures on D-channel
LAPD is the data link layer (layer 2) protocol used for
communication between the BSC and the BTS on the
Abis interface.
Abis layer 2 is sometimes used synonymously with
LAPD.
/%2
Line Build Out
/(' Light Emitting Diode
//%
Line Loop Back
/1$
Low Noise Amplifier
/RFDO EXV
The local bus offers communication between a central
main RU (DXU) and distributed main RUs (TRU and
ECU).
/RFDO PRGH
When the RU is in Local mode, it is not communicating
with the BSC.
/RFDO5HPRWH
VZLWFK
A switch used by the operator to order the RU to enter
Local or Remote mode.
/2)
Loss Of Frame
/RJLFDO &KDQQHO
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
/RJLFDO 58 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
13 (22)
EN/LZT 720 0283 Uen R1A