A multiple access, spread-spectrum communication system processes a plurality
of
information signals received by a Radio Carrier Station (RCS) over telecommunication
lines for simultaneous transmission over a radio frequency (RF) channel as a code-division-multiplexed
(CDM) signal to a group of Subscriber Units (SUs). The RCS receives a call request
signal that corresponds to a telecommunication line information signal, and a user
identification signal that identifies a user to receive the call. The RCS includes
a plurality of Code Division Multiple Access (CDMA) modems, one of which provides
a global pilot code signal. The modems provide message code signals synchronized
to the global pilot signal. Each modem combines an information signal with a message
code signal to provide a CDM processed signal. The RCS includes a system channel
controller is coupled to receive a remote call. An RF transmitter is connected
to all of the modems to combine the CDM processed signals with the global pilot
code signal to generate a CDM signal. The RF transmitter also modulates a carrier
signal with the CDM signal and transmits the modulated carrier signal through an
RF communication channel to the SUs. Each SU includes a CDMA modem which is also
synchronized to the global pilot signal. The CDMA modem despreads the CDM signal
and provides a despread information signal to the user. The system includes a closed
loop power control system for maintaining a minimum system transmit power level
for the RCS and the SUs, and system capacity management for maintaining a maximum
number of active SUs for improved system performance.
