Call Processing

Call Processing:-
Call processing puts together everything we’ve covered so far. There are slight
differences in the way the RCS and FSU process calls, so we will cover the Forward link
(RCS to FSU).
In the forward direction, the RCS:
1. Generates CDMA data signal for each traffic channel:
FEC codes the Information data, and converts the data to two-bit symbols. Converts the
symbols to I and Q data, and pads each data stream to 64 kbits/sec.Generates the
Complex PN code for each channel. Multiplies the Complex Information data and the
Complex PN code together. Reads APC data from FSU, digitally scales channels
accordingly.
2. Generates other signal channels:
Calculates APC signal, Converts it to I data only, Multiplies it with its own Complex PN
code
3. Adds all signals together:
Traffic channels, APC channel, Order Wire channel, Global Pilot
4. Adds together the signals for all currently active FSUs.
5. Modulates and transmits carriers
I and Q data modulate Cosine and Sine carriers. Carriers are combined, amplified, and
broadcast.
The FSU:
1. Extracts the I and Q data:
Receives and amplifies the modulated carriers. Demodulates the signal and extracts the I
and Q data.
2. Filters the I and Q data:
Extracts multi-path information from the Pilot Rake filter and supplies it to the Adaptive
Matched Filter. Removes multi-path interference from I and Q data using the Adaptive
Matched Filter. Performs Automatic Gain Control on received signal
3. Extracts the CDMA data signal for each traffic channel:
Generates the Complex PN code for each channel. Multiplies the Complex signal and the
Complex PN code together. Converts the I and Q data to symbols. Decodes the symbols
for error correction. Extracts the signal data.