A BTS in general has the following parts:
Its function is transmission and reception of signals.
Power amplifier (PA):
It amplifies the receiving signal.
Its combines receiving signals so that they could be sent out through a single antenna for a reduction in the number of antenna used.
It separates sending and receiving signals to/from antenna. It helps to send and receive signals through the same antenna ports.
Used to transmit signals to another entity.
Alarm extension system:
It collects working status alarms of various units in the BTS and extends them to operations and maintenance (O&M) monitoring stations.
It controls and manages the various units of BTS, including any software. It helps in On-the-spot configurations, status changes; software upgrades, etc. are done through the control function.
Baseband receiver unit (BBxx):
Frequency hopping, signal DSP, etc.