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.