3
S u b j e c t
The VX4400 phone has been designed to operate on the
l a test digital mobile commu n i c a tion tech n o l o gy, C o d e
D ivision Multiple Access (CDMA). This CDMA digi t a l
t e ch n o l o gy has gre at l y enhanced voice cl a r ity and can
p r ovide a va riety of advanced fe at u res. Curre n t ly,C D M A
mobile commu n i c a tion tech n o l ogy has been
c o m m e rc i a l ly used in Cellular and Pe rs o n a l
C o m mu n i c a tion Service (PCS).
The diffe r ence between Cellular and PCS is operat i n g
f re q u e n c y. Cellular uses 800Mhz and PCS uses 1.9Ghz.
A l s o , the VX4400 wo r ks on A d vanced Mobile Phone
S e r vice (AMPS). We call it a tri-mode phone. Since the
phone operates on Cellular, PCS and A M P S , the call fa i l
rate is less than on a conventional dual-mode or single-
mode phone.
CDMA tech n o l ogy adopts DSSS (Direct Sequence
S p read Spectrum). DSSS enables the phone to ke ep
c o m mu n i c a tion from being crossed and enables mu l t i p l e
u s e rs in the same specific area to use one fre q u e n cy
ch a n n e l , resulting in a 10 fold increase in capacity wh e n
c o m p a r ed with the analog mode curre n t ly used.
Soft/Softer Handoff, H a r d Handoff, and Dynamic RF
p ower Control tech n o l ogies are combined into this phone
to reduce call interru p t i o n s .
The Cellular and PCS CDMA netwo r ks consist of MSO
(Mobile Switching Offi c e ) , BSC (Base Stat i o n
C o n t ro l l e r ) , BTS (Base station Transmission System), a n d
MS (Mobile Station). The fo l l owing table lists some
major CDMA Standard s .
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