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each
cell can have multiple pairs of up- and downlink channels for
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data
transmission (channel streams), each stream managed by one
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logical
MDBS
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MDBS
can find out what channels are currently not assigned by
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sniffing/monitoring
control channels
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n |
before
channel is used, connection setup through control channels
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MDBS
monitors active voice channels by “sniffing” low-level radio
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frequencies
(even if no voice activity, AMPS uses in-band signaling
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at
low frequencies)
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n |
narrowband
sniffing: scans each 30 kHz channel, one at a time
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n |
wideband
sniffing: analyze all radio frequencies in the complete 12.5
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MHz
spectrum
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if
voice channels become active, MDBS initiates hop
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timing
is crucial to avoid interfering with AMPS system
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n |
MDBS
has a ramp-up and ramp-down time of 10 ms
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n |
M-ES
has ramp-up and ramp-down time of 2 ms
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