NOC is Network Operations Center… where you monitor alarms on the BTS, OSS Fiber and so on.
Base Station Controller (BSC) is in control of and supervises a number of Base Transceiver Stations (BTS).
The BSC is responsible for the allocation of radio resources to a mobile call and for the handovers that are made between base stations under his control. Maintenace of BSC is the process of preserving the state of equipments at the Bsc from all forms of alarm ranging from minor, major and critical alarms that can bring the the BSC down.
The maintenance can be done on the site or remotely from the network Monitoring Center depending on the Category of the Alarm.
But NOC is one or more locations from which network can be monitored and controlled.
All network management is exercised over a computer and with telecommunication Tools and Apps.