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| n |
data
over existing cellular systems:
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– |
modem:
costs, interoperation with handover, unreliable
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voice
channel
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CDPD:
transmit data in short bursts during idle times in
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existing
AMPS channels, use channel hopping to avoid
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collision
with voice traffic
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intersitial
cellular (proprietary to Cellular Data Inc.):
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transmit
data on unused guard bands (separate voice
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channels),
results in 2400 bit/s X.25 data network
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| n |
widely
available, limited system capacity,
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emphasis
not on data service (both new and old)
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