General Introduction - LG -TM250 Service Manual

LG-TM250

General Introduction

The LG-TM250 phone has been designed to operate on the latest digital mobile communication technology,
Code Division Multiple Access (CDMA). This CDMA digital technology has greatly enhanced voice clarity and
can provide a variety of advanced features. Currently, CDMA mobile communication technology has been
commercially used in Cellular and Personal Communication Service (PCS). The difference between them is the
operating frequency spectrum. Cellular uses 800Mhz and PCS uses 1.9Ghz. The LG-TM250 support GPS Mode,
we usually call it tri-band phone.
The CDMA technology adopts DSSS (Direct Sequence Spread Spectrum). This feature of DSSS enables the
phone to keep communication from being crossed and to use one frequency channel by multiple users in the
same specific area, resulting that it increases the capacity 10 times more compared with that in the analog mode
currently used. Soft/Softer Handoff, Hard Handoff, and Dynamic RF power Control technologies are combined
into this phone to reduce the call being interrupted in a middle of talking over the phone.
Cellular and PCS CDMA network consists of MSO (Mobile Switching Office), BSC (Base Station Controller),
BTS (Base station Transmission System), and MS (Mobile Station). The following table lists some major
CDMA Standards.
CDMA Standard
Basic air interface
Network
Service
Performance
* TSB –74: Protocol between an IS-95A system and ANSI J-STD-008
LG Electronics Inc.
Designator
TIA/EIA/IS-95-A/B/C
ANSI J-STD-008
TIA/EIA/IS-634
TIA/EIA/IS/651
TIA/EIA/IS-41-C
TIA/EIA/IS-124
TIA/EIA/IS-96-B
TIA/EIA/IS-99
TIA/EIA/IS-637
TIA/EIA/IS-657
TIA/EIA/IS-97
TIA/EIA/IS-98
ANSI J-STD-018
ANSI J-STD-019
TIA/EIA/IS-125
Description
Protocol between MS and BTS for Cellular
Protocol between MS and BTS for PCS
MAS-BS
PCSC-RS
Intersystem operations
Nom-signaling data comm.
Speech CODEC
Assign data and fax
Short message service
Packet data
Cellular base station
Cellular mobile station
PCS personal station
PCS base station
Speech CODEC
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