User's Manual

Purpose of the Optimization
08/15/2000
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SC 4812ETL BTS Optimization/ATP
PRELIMINARY
Why Optimize?
Proper optimization and calibration ensures that:
S Accurate downlink RF power levels are transmitted from the site.
S Accurate uplink signal strength determinations are made by the site.
What Is Optimization?
Optimization compensates for the site-specific cabling and normal
equipment variations. Site optimization guarantees that the combined
losses of the new cables and the gain/loss characteristics and built-in
tolerances of each BTS frame do not accumulate and cause improper site
operation.
What Happens During
Optimization
Optimization identifies the accumulated loss (or gain) for each receive
and transmit path at the BTS site, and stores these values in a database.
S A receive path (RX) starts at the ancillary equipment frame RFDS RX
directional coupler antenna feedline port and travels through the RX
input port on the top of the frame, through the bandpass filter, MPC
and additional splitter circuitry, ending at a Broad Band Transceiver
(BBX) backplane slot in the CDMA Channel Processor (CCP) shelf.
S A transmit path (TX) starts at the BBX backplane slot, is routed
through the BBX I/O to the TX Combiner, travels through the ELPA,
and ends either at an antenna port on top of the frame or RFDS TX
directional coupler antenna feedline port.
Six of the seven BBX2 boards in each S–CCP shelf are optimized to
specific RX and TX antenna ports. The seventh BBX2 board acts in a
redundant capacity for BBX2 boards 1 through 6, and is optimized to all
antenna ports. A single value is generated for each complete path,
thereby eliminating the accumulation of error that would occur from
individually measuring and summing the gain and loss of each element
in the path.
BTS equipment factors in these values internally, leaving only
site–specific antenna feed line loss and antenna gain characteristics to be
factored in by the CFE when determining site ERP output power
requirements.
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