User Manual

RBS 2000 Glossary
LAN Local Area Network
LAPD
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.
LBO
Line Build Out
LED Light Emitting Diode
LLB Line Loop Back
LNA Low Noise Amplifier
Local bus The local bus offers communication between a central
main RU (DXU) and distributed main RUs (TRU and
ECU).
Local mode
When the RU is in Local mode, it is not communicating
with the BSC.
Local/Remote
switch
A switch used by the operator to order the RU to enter
Local or Remote mode.
LOF
Loss Of Frame
Logical Channel
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
Logical RU A unit which can be referred to, but is not a single
physical unit.
LOS
Loss Of Signal
LVD
Low Voltage Directive
LVF
Low Voltage Filter
13 (22)
EN/LZT 720 0283 Uen R2A